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Sample records for earth phosphates nalnp2o7

  1. Electronic structure and optical properties of ABP2O7 double phosphates

    International Nuclear Information System (INIS)

    Hizhnyi, Yu.; Gomenyuk, O.; Nedilko, S.; Oliynyk, A.; Okhrimenko, B.; Bojko, V.

    2007-01-01

    Luminescence and luminescence excitation under VUV radiation of ABP 2 O 7 (A=Na, K, Cs; B=Al, In) double phosphates are studied. Two emission bands peaking near 330 and 420 nm are common for investigated ABP 2 O 7 crystals. The band structure and partial densities of electronic states of perfect KAlP 2 O 7 , LiInP 2 O 7 and NaTiP 2 O 7 crystals are calculated by the full-potential linear-augmented-plane-wave (FLAPW) method. It is found that the structures of the conduction bands of ABP 2 O 7 crystals, which have different B cations, are appreciably different. Experimental results are compared with results of calculations of the electronic structure. Assumptions concerning the origin of luminescence in double phosphates are made

  2. Structure of trihydrated rare-earth acid diphosphates LnHP2O7·3H2O (Ln=La, Er)

    International Nuclear Information System (INIS)

    Ben Moussa, S.; Ventemillas, S.; Cabeza, A.; Gutierrez-Puebla, E.; Sanz, J.

    2004-01-01

    In trihydrated lanthanum acid-diphosphates LnHP 2 O 7 ·3H 2 O, prepared from acid LnCl 3 and Na 4 P 2 O 7 solutions (pH=1), two crystal forms were obtained. Layered structures of two representative members of this family have been determined by single-crystal X-ray diffraction (XRD) technique. In the case of orthorhombic LaHP 2 O 7 ·3H 2 O (type I), lanthanum cations are ninefold coordinated and diphosphate groups adopt a staggered (alternated) configuration. In the case of triclinic ErHP 2 O 7 ·3H 2 O (type II), erbium cations are eightfold coordinated and diphosphate groups adopt an eclipsed configuration. In agreement with Infrared (IR) spectroscopic data, a bended configuration for diphosphate groups has been deduced. In both structures, one-dimensional chains of edge-sharing rare-earth polyhedra are linked together by diphosphate groups to form the phosphate layers. In both diphosphates, PO 4 and HPO 4 environments have been identified by 31 P MAS-NMR technique. In the two compounds, OH groups of HPO 4 tetrahedra point out of diphosphate planes interacting with adjacent layers. In La-diphosphate, the interaction between HPO 4 groups and water molecules of adjacent layers is favored; however, in Er-diphosphate, the interaction between phosphate acid groups of contiguous layers is produced. Based on structural information deduced, differences detected in IR and NMR spectra of two disphosphates are discussed

  3. Electronic structure and optical properties of ABP{sub 2}O{sub 7} double phosphates

    Energy Technology Data Exchange (ETDEWEB)

    Hizhnyi, Yu. [Faculty of Physics, Kyiv National Taras Shevchenko University, 2, Block 1, Acad. Hlushkova Ave., 03680 Kyiv (Ukraine)], E-mail: hizhnyi@univ.kiev.ua; Gomenyuk, O.; Nedilko, S.; Oliynyk, A.; Okhrimenko, B. [Faculty of Physics, Kyiv National Taras Shevchenko University, 2, Block 1, Acad. Hlushkova Ave., 03680 Kyiv (Ukraine); Bojko, V. [National Agriculture University, 5 Geroiv Oborony Str., 03041 Kyiv (Ukraine)

    2007-04-15

    Luminescence and luminescence excitation under VUV radiation of ABP{sub 2}O{sub 7} (A=Na, K, Cs; B=Al, In) double phosphates are studied. Two emission bands peaking near 330 and 420 nm are common for investigated ABP{sub 2}O{sub 7} crystals. The band structure and partial densities of electronic states of perfect KAlP{sub 2}O{sub 7}, LiInP{sub 2}O{sub 7} and NaTiP{sub 2}O{sub 7} crystals are calculated by the full-potential linear-augmented-plane-wave (FLAPW) method. It is found that the structures of the conduction bands of ABP{sub 2}O{sub 7} crystals, which have different B cations, are appreciably different. Experimental results are compared with results of calculations of the electronic structure. Assumptions concerning the origin of luminescence in double phosphates are made.

  4. The electronic structure and optical properties of ABP 2O 7 ( A = Na, Li) double phosphates

    Science.gov (United States)

    Hizhnyi, Yu. A.; Oliynyk, A.; Gomenyuk, O.; Nedilko, S. G.; Nagornyi, P.; Bojko, R.; Bojko, V.

    2008-01-01

    Partial densities of states and reflection spectra of NaAlP 2O 7, KAlP 2O 7 and LiInP 2O 7 double phosphate crystals are calculated by the full-potential linear-augmented-plane-wave (FLAPW) method. Experimental reflection spectra of KAlP 2O 7, CsAlP 2O 7 and NaInP 2O 7 are measured in the 4-20 eV energy range. The values of band gaps, Eg, are found from a comparison of experiment and calculations to be 6.0 eV for NaAlP 2O 7 and KAlP 2O 7, and 4.6 eV for LiInP 2O 7.

  5. Multiple rare-earth ion environments in amorphous (Gd2O3)0.230(P2O5)0.770 revealed by gadolinium K-edge anomalous X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Cole, Jacqueline M.; Cramer, Alisha J.; Shastri, Sarvjit D.; Mukaddem, Karim T.; Newport, Robert J

    2018-04-26

    A Gd K-edge anomalous X-ray scattering (AXS) study is performed on the rare-earth (R) phosphate glass, (Gd2O3)0.230(P2O5)0.770, in order to determine Gd…Gd separations in its local structure. The minimum rare-earth separation is of particular interest given that the optical properties of these glasses can quench when rare-earth ions become too close to each other. To this end, a weak Gd…Gd pairwise correlation is located at 4.2(1) Å which is representative of a meta-phosphate R…R separation. More intense first neighbor Gd…Gd pairwise correlations are found at the larger radial distributions, 4.8(1) Å, 5.1(1) Å and 5.4(1) Å. These reflect a mixed ultra-phosphate and meta-phosphate structural character, respectively. A second neighbor Gd…Gd pairwise correlation lies at 6.6(1) Å which is indicative of meta-phosphate structures. Meta- and ultra-phosphate classifications are made by comparing the R…R separations against those of rare-earth phosphate crystal structures, R(PO3)3 and RP5O14 respectively, or difference pair distribution function (PDF) features determined on similar glasses using difference neutron scattering methods. The local structure of this glass is therefore found to display multiple rare-earth ion environments, presumably because its composition lies between these two stoichiometric formulae. These Gd…Gd separations are well resolved in the PDFs that represent the AXS signal. Indeed, the spatial resolution is so good that it also enables the identification of R…X (X = R, P, O) pairwise correlations up to r ~ 9 Å; their average separations lie at r ~ 7.1(1) Å, 7.6(1) Å 7.9(1) Å, 8.4(1) Å and 8.7(1) Å. This is the first report of a Gd K-edge AXS study on an amorphous material. Its demonstrated ability to characterize the local structure of a glass up to such a long-range of r, heralds exciting prospects for AXS studies on other ternary non-crystalline materials. However, the technical challenge of such an experiment

  6. Investigation of the system ThO2-NpO2-P2O5. Solid solutions of thorium-neptunium (IV) phosphate-diphosphate

    International Nuclear Information System (INIS)

    Dacheux, N.; Thomas, A.C.; Brandel, V.; Genet, M.

    1998-01-01

    Considering that phosphate matrices could be potential candidates for the immobilization of actinides or for the final disposal of the excess plutonium from dismantled nuclear weapons, the chemistry of thorium phosphates has been re-examined. In the ThO 2 -P 2 O 5 system, the thorium phosphate-diphosphate Th 4 (PO 4 ) 4 P 2 O 7 (TPD) can be synthesized by wet and dry chemical processes. The substitution of thorium by other tetravalent actinides like uranium or plutonium can be obtained for 0 4-x Np x (PO 4 ) 4 P 2 O 7 (TNPD) with 0 4+ by Np 4+ in the TPD structure is evaluated to 2.08 (which corresponds to about 52 mol% of thorium replaced by neptunium (IV)). The field of existence of solid solutions Th 4-x U -x Np -x Pu U x U Np x Np Pu x Pu (PO 4 )4P 2 O 7 has been calculated. These solid solutions should be synthesized for 5x U +7x Np +9x Pu ≤15. In the NpO 2 -P 2 O 5 system, the unit cell parameters of Np 2 O(PO 4 ) 2 were refined by analogy with U 2 O(PO 4 ) 2 which crystallographic data have been published recently. For Np 2 O(PO 4 ) 2 the unit cell is orthorhombic with the following cell parameters: a=7.033(2)A, b=9.024(3)A, c=12.587(6)A and V=799(1)A 3 . The unit cell parameter obtained for α-NpP 2 O 7 (a=8.586(1)A) is in good agreement with those already reported in literature. (orig.)

  7. Spectroscopic studies of copper doped alkaline earth lead zinc phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Sastry, S. Sreehari, E-mail: sreeharisastry@yahoo.com [Department of Physics, Acharya Nagarjuna University, Nagarjunanagar 522510 (India); Rao, B. Rupa Venkateswara [Department of Physics, Acharya Nagarjuna University, Nagarjunanagar 522510 (India); Department of Physics, V.R. Siddhartha Engineering College, Vijayawada 52007 (India)

    2014-02-01

    In this paper spectroscopic investigation of Cu{sup 2+} doped alkaline earth lead zinc phosphate glasses was done through the spectroscopic techniques like X-ray diffraction, Ultra Violet (UV) absorption Spectroscopy, Electron Paramagnetic Resonance (EPR – X band), Fourier Transform Infra Red (FTIR) and Raman Spectroscopy. Alkaline earth lead zinc phosphate glasses containing 0.1% copper oxide (CuO) were prepared by the melt quenching technique. Spectroscopic studies indicated that there is a greater possibility for the copper ions to exist in Cu{sup 2+} state in these glasses. The optical absorption spectra indicated that the absorption peak of Cu{sup 2+} is a function of composition. The maxima absorption peak was reported at 862 nm for strontium lead zinc phosphate glass. Bonding parameters were calculated for the optical and EPR data. All these spectral results indicated clearly that there are certain structural changes in the present glass system with different alkaline earth contents. The IR and Raman spectra noticed the breaking of the P–O–P bonds and creating more number of new P–O–Cu bonds.

  8. Spectroscopic studies of copper doped alkaline earth lead zinc phosphate glasses

    International Nuclear Information System (INIS)

    Sastry, S. Sreehari; Rao, B. Rupa Venkateswara

    2014-01-01

    In this paper spectroscopic investigation of Cu 2+ doped alkaline earth lead zinc phosphate glasses was done through the spectroscopic techniques like X-ray diffraction, Ultra Violet (UV) absorption Spectroscopy, Electron Paramagnetic Resonance (EPR – X band), Fourier Transform Infra Red (FTIR) and Raman Spectroscopy. Alkaline earth lead zinc phosphate glasses containing 0.1% copper oxide (CuO) were prepared by the melt quenching technique. Spectroscopic studies indicated that there is a greater possibility for the copper ions to exist in Cu 2+ state in these glasses. The optical absorption spectra indicated that the absorption peak of Cu 2+ is a function of composition. The maxima absorption peak was reported at 862 nm for strontium lead zinc phosphate glass. Bonding parameters were calculated for the optical and EPR data. All these spectral results indicated clearly that there are certain structural changes in the present glass system with different alkaline earth contents. The IR and Raman spectra noticed the breaking of the P–O–P bonds and creating more number of new P–O–Cu bonds

  9. New alkali metal diphosphates how materials to preserve the security of the environment: CsNaCu(P2O7), Rb2Cu(P2O7) and CsNaCo(P2O7) synthesis and crystal structure determination

    Science.gov (United States)

    Chernyatieva, Anastasiya; Filatova, Alyona; Spiridonova, Dariya; Krivovichev, Sergey

    2013-04-01

    In this work we describe preliminary results of the synthesis and of a crystal-chemical study of synthetic phosphates with transition metals. Due to the increasing requirements for environmental safety specialists from various industries, we are searching for sustainable forms of immobilization of hazardous waste during storage. We are also developing a component-based waste for new materials. In our continued exploratory synthesis of compounds containing transition-metals, we were able to produce the new diphosphate phases CsNaCu(P2O7), Rb2Cu(P2O7) and CsNaCo(P2O7). A crystal chemical study has allowed us to identify new phosphates. Crystals of CsNaCu(P2O7) (Phase 1) is orthorhombic, crystallizes in space group Pmn21, with a = 5.147(8), b = 15.126(2), c = 9.717(2) Å, V = 756.20 Å3, R1 = 0.066 and Rb2Cu(P2O7) (Phase 2) is orthorhombic as well, crystallizes in space group Pmcn, with a = 5.183(8), b = 10.096(1), c = 15.146(3) Å, V = 793.55 Å3, R1 = 0.063, they have been obtained by high-temperature reaction of RbNO3, CsNO3, Cu(NO3)2, NaOH and (NH4)4P2O7. Synthetic crystals of the phosphate of copper and rubidium were studied in detail by us on the structures of Rb2Cu(P2O7) and Rb2Cu3(P2O7)2 - new alkali metal copper diphosphates (CHERNYATIEVA et al., 2008). Here we report the synthesis, the structure and the properties of the title compounds and we compare these phases with the previously discovered K2CuP2O7 (ELMAADI et al., 1995) and CsNaMnP2O7 (HUANG et al., 1998). These structures crystallize in other space groups, although their structures are also based on 2-D layers, formed by P2O7 groups combined with polyhedra of the transition metals (CHERNYATIEVA et al., 2012). A crystal chemical study has allowed us to identify even new diphosphates CsNaCu(P2O7) (Phase 3). Crystals of CsNaCoP2O7 is monoclinic, space group P 21/n, with a = 7,424(2), b = 7,648(1), c = 12,931(3)Å, β = 90,71(2)° , V = 734.2(3) Å3 and R1 = 0.060. The structure is based framework of Co

  10. Crystallization of rare earth germanates in the K2O-Ln2O3-GeO2-H2O at 280 deg C

    International Nuclear Information System (INIS)

    Panasenko, E.B.; Begunova, R.G.; Sklokina, N.F.

    1980-01-01

    Crystallization of rare earth germanates in potassium hydroxide solutions is studied at 280 deg C. Stability limits for different crystalline phases are established. Diorthogermanates Ln 2 O 3 x2GeO 3 (three structural modifications) are formed with all lanthanides except lanthanum. Germanates-apatites 7Ln 2 O 3 x9GeO 2 are characteristic for ''large'' lanthanides La-Nd. Alkali germanate of the composition 0.5 K 2 OxLn 2 O 3 xGeO 2 xnH 2 O is realized with the elements of the end of rare earth series, i.e., Tm-Lu. Some properties of the germanates synthesized are considered [ru

  11. Pseudopotential description of rare earths in oxides: The case of Er2Si2O7

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Stokbro, Kurt

    2001-01-01

    The applicability of ultrasoft pseudopotentials to the problem of rare-earth incorporation in silicates is investigated using the compound Er2Si2O7 as a test case. It is found that density-functional theory within the generalized gradient approximation provides a good description of the structural...... parameters, when treating the Er 4f states as a partially occupied core shell. The density of states and the distribution of electronic charge are analyzed, and it is concluded that the presence of Er tends to increase the covalency of neighboring Si-O bonds....

  12. Radiation grafting of bis[2-(methacryloyloxy)ethyl]phosphate unto kenaf fiber for adsorption of rare earth elements

    International Nuclear Information System (INIS)

    Nor Azillah Fatimah Othman; Selambakkannu, S.; Norliza Ishak; Nor Azwin Shukri; Zulkafli Ghazali

    2016-01-01

    Full text: In this work kenaf bast fibers were used as trunk polymer for grafting with bis[2-(methacryloyloxy)ethyl]phosphate monomer through radiation induced grafting technique. Kenaf fibers were treated with different concentration of sodium chlorite (NaClO_2) solution at 70 degree Celsius for 6 hours. Kenaf fibers were irradiated with electron beam and reacted with bis[2-(methacryloyloxy)ethyl]phosphate/ water emulsion. Formation of grafting was observed from the increase in degree of grafting and confirmed by FTIR and SEM results. Effects of irradiation dose, reaction time, reaction temperature and monomer concentration on the degree of grafting were studied. Performance of the grafted kenaf fibers were then tested for adsorption of rare earth elements, namely Dysprosium, Neodymium and Holmium. (author)

  13. Raman and Fluorescence Spectroscopy of CeO2, Er2O3, Nd2O3, Tm2O3, Yb2O3, La2O3, and Tb4O7

    Directory of Open Access Journals (Sweden)

    Jianlan Cui

    2015-01-01

    Full Text Available To better understand and ascertain the mechanisms of flotation reagent interaction with rare earth (RE minerals, it is necessary to determine the physical and chemical properties of the constituent components. Seven rare earth oxides (CeO2, Er2O3, Nd2O3, Tm2O3, Yb2O3, La2O3, and Tb4O7 that cover the rare earth elements (REEs from light to heavy REEs have been investigated using Raman spectroscopy. Multiple laser sources (wavelengths of 325 nm, 442 nm, 514 nm, and 632.8 nm for the Raman shift ranges from 100 cm−1 to 5000 cm−1 of these excitations were used for each individual rare earth oxide. Raman shifts and fluorescence emission have been identified. Theoretical energy levels for Er, Nd, and Yb were used for the interpretation of fluorescence emission. The experimental results showed good agreement with the theoretical calculation for Er2O3 and Nd2O3. Additional fluorescence emission was observed with Yb2O3 that did not fit the reported energy level diagram. Tb4O7 was observed undergoing laser induced changes during examination.

  14. The roles of phosphate and tungstate species in surface acidities of TiO2-ZrO2 binary oxides - A comparison study

    Science.gov (United States)

    Chaudhary, Manchal; Shen, Po-fan; Chang, Sue-min

    2018-05-01

    Porous tungstated and phosphated TiO2-ZrO2 (TZ) binary oxides with high and strong acidity were successfully prepared by means of sol-gel or impregnation approaches. In addition, the influences of the two types of modifiers on the microstructures and acidity were systematically examined, compared, and clarified. The TZ oxide derived from a surfactant-templating method exhibited a high surface area of 195 m2/g with a pore size of 6.3 nm. Moreover, it had a high acidity of 859 μmol/g with a density of 4.4 μmol/nm2 because of defective surface. Phosphation significantly increased the acidity to 1547 μmol/g and showed the highest acid density of 6.7 μmol/nm2 at a surface P density of 22.7P/nm2. On the other hand, tungstated compounds just showed the highest acidity of 972 μmol/g and the highest acid density of 4.8 μmol/nm2 at 4.7 W/nm2. Compared to tungstate species, phosphate anions are more capable of promoting the acidity because they are able to distort the host network and inhibit elemental rearrangement. While Lewis acidity prevailed in the tungstated compounds, Brønsted acidity was dominant in the phosphated oxides. The Wdbnd O and Psbnd OH groups were responsible for strong acidity in the modified compounds. Phosphated compounds formed strong Brønsted acid sites on the Psbnd OH groups with a particular strength, and tungstation produced Lewis acid sites with a continuous strength on the metal ions adjacent to the tungstate moieties. Cyclic NH3 adsorption-desorption processes revealed that the active sites for NH3 adsorption were stable in both the tungstate and phosphate modified compounds, revealing that these solid acids are promising as the adsorbents for removal of base gases.

  15. Recovery of uranium and of rare earths from Moroccan phosphates

    International Nuclear Information System (INIS)

    Ezahr, I.; El Houari, A.; Smani, S.M.

    1984-01-01

    The contents of uranium and of rare earths in Moroccan phosphates vary from 75 to 250 ppm and from 900 to 1500 ppm, respectively. The phosphates produced in Morocco contain therefore about 2500 t of uranium and 25 000 t of rare earths, compared with annual productions of uranium and of rare earths of 43 000 t and 33 000 t, respectively. During the sulphuric leaching of the phosphate ores, uranium is found to 80-90% in the phosphoric acid. Research into the extraction of uranium has shown that for the phosphoric acids produced at Safi the coefficient of extraction: is not very sensitive to the P 2 O 5 concentration on the 28-30% region; is not affected by the sulphur level up to the concentration of 4%; is very sensitive to the fluorine content beyond 1%. On the level of the first cycle of the process in Depa-Topo, four extraction stages permit a yield of between 92 and 98% to be reached. The addition of an oxidizing agent to the phosphoric acids under examination was not necessary, as their potential level is high. The purity of the yellow-cakes obtained varies from 94 to 99%. The overall recovery efficiency lies between 67 and 71%. In a second part, this paper deals with the recovery of the rare earths [fr

  16. Transport properties of the rare earth disordered systems (R1-xYbx)Ba2Cu3O7 (R = Y, Sm)

    International Nuclear Information System (INIS)

    Hwang, J.R.; Tai, M.F.; Ku, H.C.; Lii, K.H.

    1989-01-01

    Electrical and magnetic measurements have been carried out for the rare earth disordered superconducting copper oxide systems (Y 1-x Yb x )Ba 2 Cu 3 O 7 (substitution with large rare earth mass difference) and (Sm 1-x Yb x )Ba 2 Cu 3 O 7 (substitution with large rare earth ionic size difference). Effect of compositional variation upon room temperature electrical resistivity shows no disorder scattering contribution from the randomly distributed rare earth ions located on the (1/2, 1/2, 1/2) site of the space group Pmmm. This result indicates very low conduction electron density of states surrounding rare earth ions. On the contrary, negative deviation of electrical resistivity from the linear Vegard law was observed. This reduced conduction electron scattering was discussed through the variation of packing density, grain size and/or twin structure

  17. High-resolution nonresonant x-ray Raman scattering study on rare earth phosphate nanoparticles

    NARCIS (Netherlands)

    Huotari, Simo; Suljoti, Edlira; Sahle, Christoph J.; Raedel, Stephanie; Monaco, Giulio; de Groot, Frank M. F.

    2015-01-01

    We report high-resolution x-ray Raman scattering studies of high-order multipole spectra of rare earth 4d -> 4f excitations (the N-4,N-5 absorption edge) in nanoparticles of the phosphates LaPO4, CePO4, PrPO4, and NdPO4. We also present corresponding data for La 5p -> 5d excitations (the O-2,O-3

  18. High pressure phase transitions and compressibilities of Er2Zr2O7 and Ho2Zr2O7

    Science.gov (United States)

    Zhang, F. X.; Lang, M.; Becker, U.; Ewing, R. C.; Lian, J.

    2008-01-01

    Phase stability and compressibility of rare earth zirconates with the defect-fluorite structure were investigated by in situ synchrotron x-ray diffraction. A sluggish defect-fluorite to a cotunnitelike phase transformation occurred at pressures of ˜22 and ˜30GPa for Er2Zr2O7 and Ho2Zr2O7, respectively. Enhanced compressibility was found for the high pressure phase as a result of increasing cation coordination number and cation-anion bond length.

  19. High Pressure Phase Transitions and Compressibilities of Er2Zr2O7 and Ho2Zr2O7

    Energy Technology Data Exchange (ETDEWEB)

    Zhang,F.; Lang, M.; Becker, U.; Ewing, R.; Lian, J.

    2008-01-01

    Phase stability and compressibility of rare earth zirconates with the defect-fluorite structure were investigated by in situ synchrotron x-ray diffraction. A sluggish defect-fluorite to a cotunnitelike phase transformation occurred at pressures of {approx} 22 and {approx} 30 GPa for Er2Zr2O7 and Ho2Zr2O7, respectively. Enhanced compressibility was found for the high pressure phase as a result of increasing cation coordination number and cation-anion bond length.

  20. OXIDATIVE DEHYDROGENATION OF PROPANE BY RARE EARTH PHOSPHATES SUPPORTED ON AL-PILC

    Directory of Open Access Journals (Sweden)

    Carolina De Los Santos

    2012-12-01

    Full Text Available Catalytic activity in propane oxidative dehydrogenation of rare earth phosphates LnPO4 (where Ln = La, Ce, Pr, Nd, Sm and of the same supported by an aluminum pillared clay, of high specific surface area, is presented. The solids were characterized by TGA, XRD, nitrogen adsorption and immediate analysis after reaction in order to determine eventual carbon formation. Catalytic assays were performed at temperatures in the range 400oC-600oC, the reaction mixture was C3H8/O2/Ar = 10/10/80. All the catalysts were active. The reaction products were H2, CO, CO2, CH4, C2H4 and C3H6 and there were no organic oxygenated compounds detected. Although all the investigated systems were active, the Al-PILC supported catalysts presented a higher activity than the bulk materials. In this context, the samarium supported catalyst showed a propene yield increase from 4% to 10% compared with bulk samarium phosphate at 600°C. This effect was attributed to the increase in the specific surface area.

  1. Development of nano SiO2 incorporated nano zinc phosphate coatings on mild steel

    International Nuclear Information System (INIS)

    Tamilselvi, M.; Kamaraj, P.; Arthanareeswari, M.; Devikala, S.; Selvi, J. Arockia

    2015-01-01

    Highlights: • Nano SiO 2 incorporated nano zinc phosphate coating on mild steel was developed. • Coatings showed enhanced corrosion resistance. • The nano SiO 2 is adsorbed on mild steel surface and become nucleation sites. • The nano SiO 2 accelerates the phosphating process. - Abstract: This paper reports the development of nano SiO 2 incorporated nano zinc phosphate coatings on mild steel at low temperature for achieving better corrosion protection. A new formulation of phosphating bath at low temperature with nano SiO 2 was attempted to explore the possibilities of development of nano zinc phosphate coatings on mild steel with improved corrosion resistance. The coatings developed were studied by Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Electrochemical measurements. Significant variation in the coating weight, morphology and corrosion resistance was observed as nano SiO 2 concentrations varied from 0.5–4 g/L. The results showed that, the nano SiO 2 in the phosphating solution changed the initial potential of the interface between mild steel substrate and phosphating solution and reduce the activation energy of the phosphating process, increase the nucleation sites and yielded zinc phosphate coatings of higher coating weight, greater surface coverage and enhanced corrosion resistance. Better corrosion resistance was observed for coatings derived from phosphating bath containing 1.5 g/L nano SiO 2 . The new formulation reported in the present study was free from Ni or Mn salts and had very low concentration of sodium nitrite (0.4 g/L) as accelerator

  2. Theoretical Studies of the Spin Hamiltonian Parameters and Local Distortions for Cu2+ in Alkaline Earth Lead Zinc Phosphate Glasses

    Science.gov (United States)

    Wang, Bo-Kun; Wu, Shao-Yi; Yuan, Zi-Yi; Liu, Zi-Xuan; Jiang, Shi-Xin; Liu, Zheng; Yao, Zi-Jian; Teng, Bao-Hua; Wu, Ming-He

    2016-08-01

    The spin Hamiltonian parameters and local structures are theoretically studied for Cu2+-doped alkaline earth lead zinc phosphate (RPPZ, R=Mg, Ca, Sr, and Ba) glasses based on the high-order perturbation calculations for a tetragonally elongated octahedral 3d9 cluster. The relative elongation ratios are found to be ρ≈3.2%, 4.4%, 4.6%, and 3.3% for R=Mg, Ca, Sr, and Ba, respectively, because of the Jahn-Teller effect. The whole decreasing crystal-field strength Dq and orbital reduction factor k from Mg to Sr are ascribed to the weakening electrostatic coulombic interactions and the increasing probability of productivity of nonbridge oxygen (and hence increasing Cu2+-O2- electron cloud admixtures) under PbO addition, respectively, with increasing alkali earth ionic radius. The anomalies (the largest Dq and the next highest k among the systems) for R=Ba are attributed to the cross linkage of this large cation in the network. The overall increasing order (Mg≤Bacontaining copper dopants.

  3. Cathodoluminescence of rare earth implanted Ga2O3 and GeO2 nanostructures.

    Science.gov (United States)

    Nogales, E; Hidalgo, P; Lorenz, K; Méndez, B; Piqueras, J; Alves, E

    2011-07-15

    Rare earth (RE) doped gallium oxide and germanium oxide micro- and nanostructures, mostly nanowires, have been obtained and their morphological and optical properties have been characterized. Undoped oxide micro- and nanostructures were grown by a thermal evaporation method and were subsequently doped with gadolinium or europium ions by ion implantation. No significant changes in the morphologies of the nanostructures were observed after ion implantation and thermal annealing. The luminescence emission properties have been studied with cathodoluminescence (CL) in a scanning electron microscope (SEM). Both β-Ga(2)O(3) and GeO(2) structures implanted with Eu show the characteristic red luminescence peak centered at around 610 nm, due to the (5)D(0)-(7)F(2) Eu(3+) intraionic transition. Sharpening of the luminescence peaks after thermal annealing is observed in Eu implanted β-Ga(2)O(3), which is assigned to the lattice recovery. Gd(3+) as-implanted samples do not show rare earth related luminescence. After annealing, optical activation of Gd(3+) is obtained in both matrices and a sharp ultraviolet peak centered at around 315 nm, associated with the Gd(3+) (6)P(7/2)-(8)S(7/2) intraionic transition, is observed. The influence of the Gd ion implantation and the annealing temperature on the gallium oxide broad intrinsic defect band has been analyzed.

  4. Cathodoluminescence of rare earth implanted Ga2O3 and GeO2 nanostructures

    International Nuclear Information System (INIS)

    Nogales, E; Hidalgo, P; Mendez, B; Piqueras, J; Lorenz, K; Alves, E

    2011-01-01

    Rare earth (RE) doped gallium oxide and germanium oxide micro- and nanostructures, mostly nanowires, have been obtained and their morphological and optical properties have been characterized. Undoped oxide micro- and nanostructures were grown by a thermal evaporation method and were subsequently doped with gadolinium or europium ions by ion implantation. No significant changes in the morphologies of the nanostructures were observed after ion implantation and thermal annealing. The luminescence emission properties have been studied with cathodoluminescence (CL) in a scanning electron microscope (SEM). Both β-Ga 2 O 3 and GeO 2 structures implanted with Eu show the characteristic red luminescence peak centered at around 610 nm, due to the 5 D 0 - 7 F 2 Eu 3+ intraionic transition. Sharpening of the luminescence peaks after thermal annealing is observed in Eu implanted β-Ga 2 O 3 , which is assigned to the lattice recovery. Gd 3+ as-implanted samples do not show rare earth related luminescence. After annealing, optical activation of Gd 3+ is obtained in both matrices and a sharp ultraviolet peak centered at around 315 nm, associated with the Gd 3+ 6 P 7/2 - 8 S 7/2 intraionic transition, is observed. The influence of the Gd ion implantation and the annealing temperature on the gallium oxide broad intrinsic defect band has been analyzed.

  5. Self-assembled, rare earth tantalate pyrochlore nanoparticles for superior flux pinning in YBa2Cu3O7-δ films

    International Nuclear Information System (INIS)

    Harrington, S A; Durrell, J H; Wimbush, S C; Kursumovic, A; MacManus-Driscoll, J L; Maiorov, B; Wang, H; Lee, J H

    2009-01-01

    Addition of pyrochlore rare earth tantalate phases, RE 3 TaO 7 (RTO, where RE = rare earth, Er, Gd and Yb) to YBa 2 Cu 3 O 7-δ (YBCO) is shown to vastly improve pinning, without being detrimental to the superconducting transition temperature. The closely lattice matched to RTO phase provides a lower interfacial energy with YBCO than BaZrO 3 (BZO) and produces very fine (∼5 nm) particles with high linearity in their self-assembly along c. Critical current densities of 0.86, 0.38 MA cm -2 at 1 and 3 T (for fields) parallel to the c axis were recorded at 77 K in 0.5-1.0 μm thick films and a transition temperature of 92 K was observed even in the highest level doped sample (8 mol%). (rapid communication)

  6. Uptake of CrO{sub 4}{sup 2-} ions by Fe-treated tri-calcium phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Serrano G, J.; Ramirez S, J. L.; Bonifacio M, J.; Granados C, F.; Badillo A, V. E., E-mail: juan.serrano@inin.gob.m [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2010-07-01

    CrO{sub 4}{sup 2-} ion adsorption of Fe-treated tri-calcium phosphate was studied by batch experiments as a function of contact time, initial concentration of metal ion and temperature. Adsorption results showed that at ph 5.5 and 1.0 x 10{sup -4} M chromium concentration the adsorption capacity of Fe-treated tri-calcium phosphate for CrO{sub 4}{sup 2-} ions was 7.10 x 10{sup -3} mmol/g. Chromium adsorption data on Fe-treated tri-calcium phosphate at various initial concentration fitted the Freundlich isotherm. By temperature studies the thermodynamic parameters {Delta}H{sup 0}, {Delta}G{sup 0} and {Delta}S{sup 0} were estimated and the obtained results showed that the adsorption reaction was endothermic and spontaneous. (Author)

  7. Infrared and Raman investigation of rare-earth phosphate glasses for potential use as radioactive waste forms

    International Nuclear Information System (INIS)

    Morgan, S.H.

    1989-01-01

    This project was designed to investigate the properties of the rare-earth phosphate glass systems CeO 2 -P 2 O 5 and Pr 2 O 3 -P 2 O 5 for potential use as radioactive waste glasses. The glass-forming region and optimum processing parameters of these glass systems were investigated. The structure of the host glasses and glassed loaded with simulated waste elements was investigated using Raman and infrared spectroscopy. Because of the radical differences in the spectra of the molybdenum-loaded glasses, the structure of the MoO 3 -P 2 O 5 glass system was also investigated. 29 refs., 8 figs., 2 tabs

  8. Betaine Phosphate (CH3)3N+CH2COO-.H3PO4 Modification Using D2O

    International Nuclear Information System (INIS)

    Saryati; Ridwan; Deswita; Sugiantoro, Sugik

    2002-01-01

    Betaine fosfate (CH 3 ) 3 N + CH 2 COO - .H 3 PO 4 modification by using D 2 O has been studied. This modification was carried out by slowly evaporation the saturated Betaine phosphat in the D 2 O solution in the dry box at 40 o C, until the dry crystal were formed. Based on the NMR data, can be concluded that the exchange process with D has been runed well and Betaine phosphate-D (CH 3 ) 3 N + CH 2 COO - .H 3 PO 4 has been resulted. From the X-ray diffraction pattern data can be concluded that there are a deference in the crystal structure between Betaine phosphate and Betaine phosphate modification result. From the Differential Scanning Colorimeter (DSC) diagram at the range temperature from 30 o C to 250 o C, can be shown that the Betaine phosphate-H has two endothermic transition phase, at 99 o C with a very little adsorbed calor and at 221.50 o C with -26.75 cal/g. Modified Betaine phosphate has also two endothermic transition phase, at 99.86 o C with -1.94 cal/g and at 171.01 o C with -3.48 cal/g. It can be conclosed that the D atom substitution on the H atoms in Betaine phosphate, to change the crystal and the endothermic fase temperature and energy

  9. Nanoscale mechanochemical wear of phosphate laser glass against a CeO{sub 2} particle in humid air

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Jiaxin, E-mail: yujiaxin@swust.edu.cn [Key Laboratory of Testing Technology for Manufacturing Process, Ministry of Education, Southwest University of Science and Technology, Mianyang 621010 (China); He, Hongtu; Zhang, Yafeng [Key Laboratory of Testing Technology for Manufacturing Process, Ministry of Education, Southwest University of Science and Technology, Mianyang 621010 (China); Hu, Hailong [Analysis and Testing Center, Southwest University of Science and Technology, Mianyang 621010 (China)

    2017-01-15

    Highlights: • Friction components of phosphate glass/CeO{sub 2} pair in humid air were quantified to understand the friction mechanism. • Severe nanoscale wear was directly observed by AFM topography on both phosphate glass and CeO{sub 2} particle in humid air. • The wearless behaviors of phosphate glass in vacuum were confirmed by the AFM phase image. • Capillary water bridge induced corrosion plays an important role in the mechanochemical wear of phosphate glass in air. - Abstract: Using an atomic force microscope, the friction and wear of phosphate laser glass against a CeO{sub 2} particle were quantitatively studied both in humid air and in vacuum, to reveal the water molecules induced mechanochemical wear mechanism of phosphate laser glass. The friction coefficient of the glass/CeO{sub 2} pair in air was found to be 5–7 times higher than that in vacuum due to the formation of a capillary water bridge at the friction interface, with a contribution of the capillary-related friction to the total friction coefficient as high as 65–79%. The capillary water bridge further induced a serious material removal of glass and CeO{sub 2} particle surfaces, while supplying both a local liquid water environment to corrode the glass surface and a high shearing force to assist the stretching of the Ce−O−P bond, accelerating the reaction between water and the glass/CeO{sub 2} pair. In vacuum, however, no discernable wear phenomena were observed, but the phase images captured by AFM tapping mode suggested the occurrence of potential strain hardening in the friction area of the glass surface.

  10. Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}: A new telluro-phosphate with S=1/2 Heisenberg chain

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Mingjun [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Shen, Shipeng; Lu, Jun; Sun, Young [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Li, R.K., E-mail: rkli@mail.ipc.ac.cn [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-10-15

    A new telluro-phosphate compound Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} with S=1/2 Heisenberg chain has been successfully synthesized by solid state reaction and grown by flux method. Single crystal X-ray diffraction reveals that Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} crystallizes into a monoclinic space group C2/c and cell parameters of a=17.647(3) Å, b=7.255(2) Å, c=9.191(2) Å and β=100.16 (3)°. In the structure of Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}, one dimensional [CuTePO{sub 7}]{sup 3−} chains are formed by tetrahedral PO{sub 4} and trigonal bi-pyramidal TeO{sub 4} joining square planar CuO{sub 4} groups. Those [CuTePO{sub 7}]{sup 3−} chains are inter-connected by sharing one oxygen atom from the TeO{sub 4} group to form two dimensional layers. Magnetic susceptibility and specific heat measurements confirm that the title compound is a model one dimensional Heisenberg antiferromagnetic chain system. - Graphical abstract: Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}, containing (CuTePO{sub 7}){sup 3−} chains formed by PO{sub 4} and TeO{sub 4} joining CuO{sub 4} groups, shows typical 1D Heisenberg antiferromagnetic chain model behavior as confirmed by magnetic measurements. - Highlights: • New telluro-phosphate Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} has been grown. • It features layered structure composed of [CuTePO{sub 7}]{sup 3−} chains and TeO{sub 4} groups. • It shows the Heisenberg antiferromagnetic chain behavior. • It is transparent in the range of 1000–2500 nm with a UV absorption edge of 393 nm.

  11. Structure of RbAlAs[sub 2]O[sub 7]. Structure de RbAlAs[sub 2]O[sub 7

    Energy Technology Data Exchange (ETDEWEB)

    Boughzala, H. (Dept. de Chimie, Faculte des Sciences, Tunis (Tunisia)); Driss, A. (Dept. de Chimie, Faculte des Sciences, Tunis (Tunisia)); Jouini, T. (Dept. de Chimie, Faculte des Sciences, Tunis (Tunisia))

    1993-03-15

    Rubidium aluminium pyroarsenate, M[sub r]=374.29, triclinic, P anti 1, a=8.233(5), b=6.34(2), c=6.241(5) A, [alpha]=102.6(1), [beta]=103.89(7), [gamma]=96.7(1) , V=303.9 A[sup 3], Z=2, D[sub m]=3.9(3) (pycnometry), D[sub x]=4.09 g cm[sup -3], [lambda](Ag K anti [alpha])=0.5608 A, [mu]=108.14 cm[sup -1], F(000)=344, T=296 K, R=0.049, wR=0.053 for 2193 reflections. The first structural investigation on a pyroarsenate is reported. It is built from AlAs[sub 2]O[sub 11] units comprising one AlO[sub 6] octahedron and one As[sub 2]O[sub 7] pyroarsenate group in which two AsO[sub 4] tetrahedra point in opposite directions. These units are connected by heteropolyhedral linkages to form a three-dimensional framework having intersecting tunnels where the Rb[sup +] ions are located. Although this structure is not isotypic with the phosphate analogues, it is closely related to that of the pyrophosphates of type I represented by KAlP[sub 2]O[sub 7]. (orig.).

  12. Synthesis and photoluminescence study of rare earth activated phosphor Na2La2B2O7

    International Nuclear Information System (INIS)

    Nagpure, P.A.; Omanwar, S.K.

    2012-01-01

    The photoluminescence properties in UV and N-UV excitable range for the phosphors of Na 2 La 2 B 2 O 7 : RE (RE=Eu, Tb, Ce, Sm, Gd) are investigated. The solution combustion synthesis technique was employed for the synthesis of the phosphors Na 2 La 2 B 2 O 7 : RE. The photoluminescence measurements of the phosphors were carried out on a HITACHI F7000 Fluorescence Spectrophotometer. The PL and PL excitation (PLE) spectra indicate that the main emission wavelength of Na 2 La 2 B 2 O 7 : Eu are 591 and 615 nm, Na 2 La 2 B 2 O 7 : Ce shows dominating emission peak at 387 nm and Na 2 La 2 B 2 O 7 : Tb displays green emission at 493, 544, 593 and 620 nm at 254 nm excitation, while Na 2 La 2 B 2 O 7 : Sm shows the main emission peak wavelengths 566 and 604 nm at 405 nm excitation and Na 2 La 2 B 2 O 7 : Gd shows dominating emission peak at 312 nm at 274 nm excitation. These phosphors may provide a new kind of luminescent materials under ultraviolet and near ultraviolet excitation for various applications. - Highlights: ► We use the combustion technique for synthesis of Na 2 La 2 B 2 O 7 : RE phosphor. ► Phosphor Na 2 La 2 B 2 O 7 : Eu 3+ shows intense red emission under UV excitation. ► Phosphor Na 2 La 2 B 2 O 7 : Tb 3+ shows intense green emission under UV excitation. ► Phosphor Na 2 La 2 B 2 O 7 : Sm 3+ shows orange red emission under near UV excitation. ► Phosphors Na 2 La 2 B 2 O 7 : Ce 3+ and Na 2 La 2 B 2 O 7 : Gd 3+ show near UV and UVB emissions under UV excitation.

  13. Synergistic effect of PANI-ZrO2 composite as antibacterial, anti-corrosion, and phosphate adsorbent material: synthesis, characterization and applications.

    Science.gov (United States)

    Masim, Frances Camille P; Tsai, Cheng-Hsien; Lin, Yi-Feng; Fu, Ming-Lai; Liu, Minghua; Kang, Fei; Wang, Ya-Fen

    2017-11-03

    The increasing number of bacteria-related problems and presence of trace amounts of phosphate in treated wastewater effluents have become a growing concern in environmental research. The use of antibacterial agents and phosphate adsorbents for the treatment of wastewater effluents is of great importance. In this study, the potential applications of a synthesized polyaniline (PANI)-zirconium dioxide (ZrO 2 ) composite as an antibacterial, phosphate adsorbent and anti-corrosion material were systematically investigated. The results of an antibacterial test reveal an effective area of inhibition of 14 and 18 mm for the Escherichia coli and Staphylococcus aureus bacterial strains, respectively. The antibacterial efficiency of the PANI-ZrO 2 composite is twice that of commercial ZrO 2 . In particular, the introduction of PANI increased the specific surface area and roughness of the composite material, which was beneficial to increase the contact area with bacterial and phosphate. The experimental results demonstrated that phosphate adsorption studies using 200 mg P/L phosphate solution showed a significant phosphate removal efficiency of 64.4%, and the maximum adsorption capacity of phosphate on the solid surface of PANI-ZrO 2 is 32.4 mg P/g. Furthermore, PANI-ZrO 2 coated on iron substrate was tested for anti-corrosion studies by a natural salt spray test (7.5% NaCl), which resulted in the formation of no rust. To the best of our knowledge, no works have been reported on the synergistic effects of the PANI-ZrO 2 composite as an antibacterial, anti-corrosion, and phosphate adsorbent material. PANI-ZrO 2 composite is expected to be a promising comprehensive treatment method for water filters in the aquaculture industry and for use in water purification applications.

  14. Thermodynamic studies of thorium phosphate diphosphate and phase investigations of Th-P-O and Th-P-H2O systems

    International Nuclear Information System (INIS)

    Rawat, Deepak; Dash, Smruti; Joshi, A.R.

    2014-01-01

    Highlights: • Δ f H m o (298.15K)andC p,m o (T) of Th 2 P 3 O 13 H 3 (cr), Th 2 P 3 O 12 H(cr), α-Th 4 P 6 O 23 (cr) and β-Th 4 P 6 O 23 (cr) were measured. • Thermo-chemical reaction scheme was formulated to calculate the standard molar enthalpy of formation of β-Th 4 (PO 4 ) 4 P 2 O 7 (cr). • The thermodynamic functions of the compounds present in Th-P-O and Th-P-H 2 O systems have been estimated. • The Gibbs phase diagram and predominant area diagrams for Th-P-O system have been calculated. • E H –pH diagram of Th-P-H 2 O system has been computed to determine stability of β-Th 4 P 6 O 23 (cr) in the ground water. - Abstract: The standard molar enthalpy of formation of thorium phosphate diphosphate, β-Th 4 (PO 4 ) 4 P 2 O 7 (cr) has been determined using an isoperibol solution calorimeter, a differential scanning calorimeter and phase transition data of high temperature calorimeter. The enthalpy of precipitation of thorium phosphate-hydrogenphosphate hydrate, Th 2 (PO 4 ) 2 (HPO 4 )·H 2 O(cr), was measured at 298.15 K using an isoperibol solution calorimeter. Heat capacities of α-Th 4 (PO 4 ) 4 P 2 O 7 (cr) and β-Th 4 (PO 4 ) 4 P 2 O 7 (cr) were measured using a Differential Scanning Calorimeter. Combining these experimental data, and other auxiliary data from the literature, thermo-chemical reaction scheme was devised to calculate the standard molar enthalpy of formation of β-Th 4 (PO 4 ) 4 P 2 O 7 (cr) to be {−10565.5 ± 13.6} kJ mol −1 . The thermodynamic functions for β-Th 4 (PO 4 ) 4 P 2 O 7 (cr) have been computed using Δ f H m o (298.15K),C p,m o (T) and literature data. The Gibbs phase diagram and predominant area diagrams for Th-P-O system have been computed using the thermodynamic information of the various phase present in Th-P, P-O and ThO 2 -P 2 O 5 systems. E H –pH diagram of Th-P-H 2 O system has been computed to determine stability of Th 4 P 6 O 23 (cr) in ground water

  15. Ultrafast phosphate hydration dynamics in bulk H2O

    Science.gov (United States)

    Costard, Rene; Tyborski, Tobias; Fingerhut, Benjamin P.; Elsaesser, Thomas

    2015-06-01

    Phosphate vibrations serve as local probes of hydrogen bonding and structural fluctuations of hydration shells around ions. Interactions of H2PO4- ions and their aqueous environment are studied combining femtosecond 2D infrared spectroscopy, ab-initio calculations, and hybrid quantum-classical molecular dynamics (MD) simulations. Two-dimensional infrared spectra of the symmetric ( ν S ( PO2 - ) ) and asymmetric ( ν A S ( PO2 - ) ) PO 2- stretching vibrations display nearly homogeneous lineshapes and pronounced anharmonic couplings between the two modes and with the δ(P-(OH)2) bending modes. The frequency-time correlation function derived from the 2D spectra consists of a predominant 50 fs decay and a weak constant component accounting for a residual inhomogeneous broadening. MD simulations show that the fluctuating electric field of the aqueous environment induces strong fluctuations of the ν S ( PO2 - ) and ν A S ( PO2 - ) transition frequencies with larger frequency excursions for ν A S ( PO2 - ) . The calculated frequency-time correlation function is in good agreement with the experiment. The ν ( PO2 - ) frequencies are mainly determined by polarization contributions induced by electrostatic phosphate-water interactions. H2PO4-/H2O cluster calculations reveal substantial frequency shifts and mode mixing with increasing hydration. Predicted phosphate-water hydrogen bond (HB) lifetimes have values on the order of 10 ps, substantially longer than water-water HB lifetimes. The ultrafast phosphate-water interactions observed here are in marked contrast to hydration dynamics of phospholipids where a quasi-static inhomogeneous broadening of phosphate vibrations suggests minor structural fluctuations of interfacial water.

  16. Effect of rare-earth ion size on local electron structure in RBa2Cu3O7-δ (R = Tm, Dy, Gd, Eu, Nd and Y) superconductors: A positron study

    International Nuclear Information System (INIS)

    Chen Zhenping; Zhang Jincang; Su Yuling; Xue Yuncai; Cao Shixun

    2006-01-01

    The effects of rare-earth ionic size on the local electron structure, lattice parameters and superconductivity have been investigated by positron annihilation technique (PAT) and related experiments for RBa 2 Cu 3 O 7-δ (R = Tm, Dy, Gd, Eu, Nd and Y) superconductors. The local electron density n e is evaluated as a function of the rare-earth radius. The results show that both the bulk-lifetime τ B and the defect lifetime τ 2 increase with increasing rare-earth ionic radius, while the local electron density n e decrease with increasing rare-earth ionic radius. These results prove that the changes of n e , the degree of orthorhombic distortion and the coupling between the Cu-O chains and the CuO 2 planes all have an effect on the superconductivity of RBa 2 Cu 3 O 7-δ systems

  17. Effect of alkaline earth modifier on the optical and structural properties of Cu2+ doped phosphate glasses as a bandpass filter

    Science.gov (United States)

    Farouk, M.; Samir, A.; El Okr, M.

    2018-02-01

    Glasses of composition [16RO-3Al2O3sbnd 6CuOsbnd 20Na2Osbnd 55P2O5], where R is the alkaline earth (R = Mg, Ca, Sr and Ba mol. %), were prepared by conventional melt quenching technique. The glass samples were characterized by X-ray diffraction, infrared spectroscopy, and spectrophotometer. XRD patterns show no sharp peaks indicating the non-crystalline nature of the prepared glasses. The density and molar volume of the glass systems were determined in order to study their structures. These results revealed that addition of alkaline earth elements leads to the formation of non-bridging oxygens (NBOs) and expands (opens up) the structure. The infrared spectra were analyzed to quantify the present phosphate groups. The optical absorption spectra of Cu2+ ions show the characteristic broadband single of Cu2+ ions in octahedral symmetry. The band gap was estimated following two methodologies. The first method considers the band edge of the transmission, while the second approach relays on the estimated values of the optical constants. A decent agreement for the band gap values using the two methods was obtained.

  18. Influence of rare-earth ions on SiO{sub 2}-Na{sub 2}O-RE{sub 2}O{sub 3} glass structure

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J A [Department of Materials Science and Engineering, University of Tennessee Space Institute, Tullahoma, TN 37388 (United States); Benmore, C J [X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Holland, D [Department of Physics, University of Warwick, CV4 7AL (United Kingdom); Du, J [Department of Material Science and Engineering, University of North Texas, Denton, TX 76203 (United States); Beuneu, B [Laboratoire Leon Brillouin, CEA-CNRS, CEA/Saclay, F-91191 Gif-sur-Yvette (France); Mekki, A, E-mail: jjohnson@utsi.edu [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

    2011-02-16

    Praseodymium and europium sodium silicate glasses of nominal composition (SiO{sub 2}){sub 0.70-x}(Na{sub 2}O){sub 0.30}(RE{sub 2}O{sub 3}){sub x}, where RE is the rare earth and 0 {<=} x {<=} 0.10, were studied by neutron and high-energy x-ray scattering and classical molecular dynamics simulations. The observation of a significant x-ray intensity in doped as compared to un-doped glasses is indicative of RE-RE correlations at a distance of {approx} 3.7-3.9 A, much shorter than would be expected for a homogeneous distribution, suggesting that clustering of the rare-earth cations occurs in both these glass systems at low concentrations. Above x = 0.075 (nominal), minimal changes in this region indicate that the RE atoms are incorporated much more randomly into the glass structure. The molecular dynamics simulations suggest that the rare-earth ions enter the sodium-rich regions in the sodium silicate glasses and act as modifiers. A cluster analysis performed on the model systems indicates that the tendency for clustering is higher in praseodymium-containing glasses than in the europium glasses.

  19. Phase diagrams of systems of Sr2V2O7-M2V2O7 and of Ba2V2O7-M2V2O7 (M=Ca,Cd)

    International Nuclear Information System (INIS)

    Fotiev, A.A.; Zhuravlev, V.D.; Zhukov, V.P.

    1982-01-01

    Using the methods of X-ray phase and differential thermal anlyses phase equilibria in the systems Sr 2 V 2 O 7 -M 2 V 2 O 7 and Ba 2 V 2 O 7 -M 2 V 2 O 7 , where M--Ca, Cd, are studied, their phase diagrams being built. New double pyrovanadates Mosub(0.5)Srsub(1.5)Vsub(2)Osub(7) and MBaV 2 O 7 are found [ru

  20. Procedure for the separation of cerium from rare earth phosphate mixtures

    International Nuclear Information System (INIS)

    Richter, H.; Grauss, H.; Schmitt, A.; Schade, H.; Lindeholz, M.; Lorenz, E.; Weickart, J.

    1986-01-01

    The invention is concerned with a procedure for the separation of cerium from rare earth concentrates originating from the partial neutralization of nitric crude phosphate decomposition solutions without preceding elimination of impurities from the raw material. The rare earth phosphates are treated with an excess of concentrated nitric acid through which the Ce 3+ , contained in the solution, is oxidized to Ce 4+ and precipitated as cerium(IV) phosphate by neutralization with alkalis

  1. Ultrafast phosphate hydration dynamics in bulk H2O

    International Nuclear Information System (INIS)

    Costard, Rene; Tyborski, Tobias; Fingerhut, Benjamin P.; Elsaesser, Thomas

    2015-01-01

    Phosphate vibrations serve as local probes of hydrogen bonding and structural fluctuations of hydration shells around ions. Interactions of H 2 PO 4 − ions and their aqueous environment are studied combining femtosecond 2D infrared spectroscopy, ab-initio calculations, and hybrid quantum-classical molecular dynamics (MD) simulations. Two-dimensional infrared spectra of the symmetric (ν S (PO 2 − )) and asymmetric (ν AS (PO 2 − )) PO 2 − stretching vibrations display nearly homogeneous lineshapes and pronounced anharmonic couplings between the two modes and with the δ(P-(OH) 2 ) bending modes. The frequency-time correlation function derived from the 2D spectra consists of a predominant 50 fs decay and a weak constant component accounting for a residual inhomogeneous broadening. MD simulations show that the fluctuating electric field of the aqueous environment induces strong fluctuations of the ν S (PO 2 − ) and ν AS (PO 2 − ) transition frequencies with larger frequency excursions for ν AS (PO 2 − ). The calculated frequency-time correlation function is in good agreement with the experiment. The ν(PO 2 − ) frequencies are mainly determined by polarization contributions induced by electrostatic phosphate-water interactions. H 2 PO 4 − /H 2 O cluster calculations reveal substantial frequency shifts and mode mixing with increasing hydration. Predicted phosphate-water hydrogen bond (HB) lifetimes have values on the order of 10 ps, substantially longer than water-water HB lifetimes. The ultrafast phosphate-water interactions observed here are in marked contrast to hydration dynamics of phospholipids where a quasi-static inhomogeneous broadening of phosphate vibrations suggests minor structural fluctuations of interfacial water

  2. Optical and structural characterization of rare earth doped niobium phosphate glasses

    International Nuclear Information System (INIS)

    Sene, F.F.; Martinelli, J.R.; Gomes, L.

    2004-01-01

    Phosphate glasses containing up to 45mol% of niobium were obtained. X-ray diffraction, infrared, Raman, and optical absorption spectroscopy were used to analyze those materials. The refractive index varies from 1.70 to 1.85 as the amount of Nb increases. Niobium phosphate glasses with optical transparence in the (400-2500nm) range were produced. The cut off varied from 342nm to 378nm as a function of the Nb concentration. The cut off is due to the charge transfer O 2 ->Nb 5+ . Glasses containing 10mol% of Nb 2 O 5 are the most promising materials to be used as rare-earth ions hosts because they are chemically resistant, and show optical transparency in the spectral range of visible to infrared. Doping the glasses with 1-5mol% of Er, Ho, Pr, and Yb ions does not change the glass structure, as measured by X-ray diffraction, infrared, and Raman spectroscopy. The fluorescence lifetimes were determined for Nd, Yb, and Er, and the absorption cross-section were determined for all ions. The energy transfer in co-doped Yb-Er system was measured, and the lifetime of excited states and the luminescence efficiency were determined to be 91% for the Er 4 I 11/2 level, in the Yb-Er co-doped glasses

  3. Structure and spectroscopy of rare earth – Doped lead phosphate glasses

    International Nuclear Information System (INIS)

    Pisarski, Wojciech A.; Żur, Lidia; Goryczka, Tomasz; Sołtys, Marta; Pisarska, Joanna

    2014-01-01

    Highlights: • Lead phosphate glasses doped with rare earth ions were prepared. • The local structure was examined using X-ray diffraction and spectroscopic methods. • Different structural phosphate groups are present in lead phosphate glasses. • The electron–phonon coupling strength and phonon energy of the glass host was determined. • Several observed emission bands are due to 4f–4f electronic transitions of rare earth ions. -- Abstract: Lead–gallium phosphate glasses doped with rare the earth ions (Eu 3+ , Dy 3+ , Tb 3+ , Er 3+ ) were synthesized. The structure of obtained glasses was examined by means of use: X-ray diffraction (XRD), nuclear magnetic resonance ( 207 Pb and 31 P NMR), fourier transform infrared (FT-IR) and Raman spectroscopy. In contrast to fully amorphous Ln-doped samples (Ln = Eu, Dy, Tb), in Er-doped sample the GaPO 4 crystalline phase was identified. It was found from the NMR, FT-IR and Raman spectroscopic techniques that, different structural phosphate groups were present in lead phosphate glasses. Based on absorption measurements, the UV–VIS cut-off wavelength for lead phosphate glass was determined and its value is close to 305 nm. Excitation and emission spectra of rare earths were also detected. From excitation spectra of Eu 3+ the electron–phonon coupling strength and phonon energy of the glass host were determined. Due to 4f 6 –4f 6 (Eu 3+ ), 4f 8 –4f 8 (Tb 3+ ), 4f 9 –4f 9 (Dy 3+ ) and 4f 11 –4f 11 (Er 3+ ) electronic transitions of trivalent rare earth ions several luminescence bands were stated

  4. Theoretical studies of the spin Hamiltonian parameters and local distortions for Cu{sup 2+} in alkaline earth lead zinc phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bo-Kun; Yuan, Zi-Yi; Liu, Zi-Xuan; Jiang, Shi-Xin; Liu, Zheng; Yao, Zi-Jian [University of Electronic Science and Technology of China, Chengdu (China). School of Yingcai Honors; Wu, Shao-Yi; Teng, Bao-Hua; Wu, Ming-He [University of Electronic Science and Technology of China, Chengdu (China). Dept. of Applied Physics

    2016-11-01

    The spin Hamiltonian parameters and local structures are theoretically studied for Cu{sup 2+}-doped alkaline earth lead zinc phosphate (RPPZ, R=Mg, Ca, Sr, and Ba) glasses based on the high-order perturbation calculations for a tetragonally elongated octahedral 3d{sup 9} cluster. The relative elongation ratios are found to be ρ ∼ 3.2%, 4.4%, 4.6%, and 3.3% for R=Mg, Ca, Sr, and Ba, respectively, because of the Jahn-Teller effect. The whole decreasing crystal-field strength Dq and orbital reduction factor k from Mg to Sr are ascribed to the weakening electrostatic coulombic interactions and the increasing probability of productivity of nonbridge oxygen (and hence increasing Cu{sup 2+}-O{sup 2-} electron cloud admixtures) under PbO addition, respectively, with increasing alkali earth ionic radius. The anomalies (the largest Dq and the next highest k among the systems) for R=Ba are attributed to the cross linkage of this large cation in the network. The overall increasing order (Mg≤Ba2+}-O{sup 2-} bonds. The present studies would be helpful to understand local structures and the influences on the optical properties of RPPZ glasses containing copper dopants.

  5. In vitro bioactivity behavior of modified multicomponent borate glasses containing dopants of Ag2O, CuO, CeO2 or V2O5

    Science.gov (United States)

    Marzouk, M. A.; ElBatal, F. H.; Ghoneim, N. A.

    2018-02-01

    Some multi-component borate glasses containing dopants of Ag2O, CuO, CeO2 or V2O5 were prepared. Multi-characterization techniques were carried out to investigate their bioactivity, corrosion weight loss after immersion in phosphate solution. Controlled thermal heat-treatment by two-step technique was done to convert the prepared glasses to their corresponding glass-ceramic derivatives. X-ray diffraction analysis was performed to identify the crystalline phases formed by thermal treatment. Infrared absorption of glasses and glass-ceramics reveal vibrational bands due to combined main triangular and tetrahedral borate groups in their specific wavenumbers besides some sharing of phosphate group. After immersion in the phosphate solution, two extra characteristic peaks are generated indicating the bioactivity of the studied glasses and glass-ceramics through the formation of calcium phosphate (hydroxyapatite). X-ray diffraction data indicate the formation of crystalline phases which are variable with the introduced dopants. The main crystalline phase identified is calcium borate together with some other phases some of which contain phosphate ions. These data indicate that the presence of CaO and P2O5 initiates phase separation and subsequent crystallization of the parent and doped glasses. Weight loss data indicate that glass-ceramics are obviously durable than the parent glasses. SEM micrographs of glass-ceramics before immersion show multiconstituent crystalline phases due to the basic chemical composition consisting of multicomponent mixed alkali and alkaline earth oxides beside P2O5 and with the main B2O3 constituent. After immersion, the crystalline phases are identified to be more distinct in different shapes because of the multi-composition involved.

  6. Earth's early O2 cycle suppressed by primitive continents

    Science.gov (United States)

    Smit, Matthijs A.; Mezger, Klaus

    2017-10-01

    Free oxygen began to accumulate in Earth's surface environments between 3.0 and 2.4 billion years ago. Links between oxygenation and changes in the composition of continental crust during this time are suspected, but have been difficult to demonstrate. Here we constrain the average composition of the exposed continental crust since 3.7 billion years ago by compiling records of the Cr/U ratio of terrigenous sediments. The resulting record is consistent with a predominantly mafic crust prior to 3.0 billion years ago, followed by a 500- to 700-million-year transition to a crust of modern andesitic composition. Olivine and other Mg-rich minerals in the mafic Archaean crust formed serpentine minerals upon hydration, continuously releasing O2-scavenging agents such as dihydrogen, hydrogen sulfide and methane to the environment. Temporally, the decline in mafic crust capable of such process coincides with the first accumulation of O2 in the oceans, and subsequently the atmosphere. We therefore suggest that Earth's early O2 cycle was ultimately limited by the composition of the exposed upper crust, and remained underdeveloped until modern andesitic continents emerged.

  7. YBa2Cu3O7-δ/NdBa2(Cu1-xNix)3O7-δ double layers by liquid-phase epitaxial growth

    International Nuclear Information System (INIS)

    Yao, X.; Izumi, Toru; Hobara, Natsuro; Nakamura, Yuichi; Izumi, Teruo; Shiohara, Yuh

    2001-01-01

    Our present investigation has answered questions pertaining to the REBa 2 Cu 3 O 7-δ (RE123, RE=rare-earth elements)-coated conductor application when NdBa 2 (Cu 1-x Ni x ) 3 O 7-δ (Ni-NdBCO) solid solution is used as a buffer layer by the liquid-phase epitaxy(LPE) process. The NiO/Ni substrate has no substantial reaction in the Ni-saturated Nd-Ba-Cu-O liquid. There is no essential Ni interdiffusion between YBa 2 Cu 3 O 7-δ (YBCO) and Ni-NdBCO LPE thick films as evident from T c values of 90 K obtained from multilayer YBCO/Ni-NdBCO samples. (author)

  8. Study on the water durability of zinc boro-phosphate glasses doped with MgO, Fe2O3, and TiO2

    Science.gov (United States)

    Hwang, Moon Kyung; Ryu, Bong Ki

    2016-07-01

    The water durability of zinc boro-phosphate (PZB) glasses with the composition 60P2O5-20ZnO-20B2O3- xMeO ( x = 0, 2, 4, 6 and MeO = MgO, Fe2O3, or TiO2) (mol%) was measured, and PZB glass was studied in terms of its thermal properties, density, and FTIR characteristics. The surface conditions and corrosion byproducts were analyzed using scanning electron microscopy. When MgO, Fe2O3, and TiO2 were doped into the PZB glass, Q2 was decreased and Q1 was increased in the phosphate structure, while the number of BO4 structures increased with increasing MeO content. The density of the PZB glass was increased by the addition of Fe2O3 and TiO2, while the glass transition temperature ( T g ) and dilatometric softening temperature ( T d ) were increased when additional MgO, Fe2O3, and TiO2 were added. From the weight loss analysis (95 ◦ C, 96 h), TiO2 doped glass showed the lowest weight loss (1.70 × 10 -3 g/cm2) while MgO doped glass showed the highest value (2.44 × 10 -3 g/cm2), compared with PZB glass (3.07 × 10 -3 g/cm2). These results were discussed in terms of the Me n+ ions in the glass structure, and their different coordination numbers and bonding strengths.

  9. Radiation damage produced by swift heavy ions in rare earth phosphates

    International Nuclear Information System (INIS)

    Romanenko, Anton

    2017-01-01

    This work is devoted to the study of radiation damage produced by swift heavy ions in rare earth phosphates, materials that are considered as perspective for radioactive waste storage. Single crystals of rare earth phosphates were exposed to 2.1 GeV gold (Au) and 1.5 GeV xenon (Xe) ions of and analyzed mainly by Raman spectroscopy. All phosphates were found almost completely amorphous after the irradiation by 2.1 GeV Au ions at a fluence of 1 x 10 13 ions/cm 2 . Radiation-induced changes in the Raman spectra include the intensity decrease of all Raman bands accompanied by the appearance of broad humps and a reduction of the pronounced luminescence present in virgin samples. Analyzing the Raman peak intensities as a function of irradiation fluence allowed the calculation of the track radii for 2.1 GeV Au ions in several rare earth phosphates, which appear to be about 5.0 nm for all studied samples. Series of samples were studied to search for a trend of the track radius depending on the rare earth element (REE) cation. Among the monoclinic phosphates both Raman and small-angle X-ray scattering (SAXS) suggest no significant change of the track radius with increasing REE mass. In contrast, within the tetragonal phosphates Raman spectroscopy data suggests a possible slight decreasing trend of the track radius with the increase of REE atomic number. That finding, however, requires further investigation due to the low reliability of the qualitative Raman analysis. Detailed analysis of Raman spectra in HoPO 4 showed the increase of peak width at the initial stage of the irradiation and subsequent decrease to a steady value at higher fluences. This observation suggested the existence of a defect halo around the amorphous tracks in HoPO 4 . Raman peaks were found to initially shift to lower wavenumbers with reversing this trend at the fluence of 5 x 10 11 for NdPO 4 and 1 x 10 12 ions/cm 2 for HoPO 4 . At the next fluence steps peaks moved in the other direction, passed

  10. A Novel Framework Antimony (III) Phosphate: Synthesis and Structure of NaSb 3O 2(PO 4) 2

    Science.gov (United States)

    Adair, Brian A.; de Delgado, Graciela Díaz; Miguel Delgado, J.; Cheetham, Anthony K.

    2000-04-01

    The antimony (III) phosphate, NaSb3O2(PO4)2, is a framework structure built from SbIII and PV centers; orthorhombic, space group Pca21 (No. 29), a=13.944(3), b=6.6822(13), c=20.886(4) Å, V=1946.1(7) Å3, Z=8. Stereochemically active lone pairs of electrons associated with SbIIIO5 and SbIIIO4 polyhedra point into eight-ring channels, approximately 5×7 Å2, which dominate the architecture of the title compound. Charge-compensating sodium cations occupy the remaining space in the channels.

  11. Procedure for the separation of cerium from crude phosphates and rare earth concentrates

    International Nuclear Information System (INIS)

    Richter, H.; Koenig, O.; Schmitt, A.; Grauss, H.; Freitag, S.

    1986-01-01

    The invention has to do with a procedure for the separation of cerium from crude phosphates and rare earth phosphate concentrates originating from the partial neutralization of nitric crude phosphate decomposition solutions. It is aimed at the cerium separation from the raw material at an early stage of reprocessing without preceding elimination of other components and impurities. The rare earth phosphate concentrates or crude phosphates are dissolved in nitric acid, the Ce 3+ is oxidized with potassium permanganate or magnanese(IV) hydroxide, and cerium(IV) phosphate is precipitated as pure substance by decreasing the acidity of the solution

  12. Na2MoO2As2O7

    Directory of Open Access Journals (Sweden)

    Raja Jouini

    2012-12-01

    Full Text Available Disodium molybdenum dioxide diarsenate, Na2MoO2As2O7, has been synthesized by a solid-state reaction. The structure is built up from MoAs2O12 linear units sharing corners to form a three-dimensional framework containing tunnels running along the a-axis direction in which the Na+ cations are located. In this framework, the AsV atoms are tetrahedrally coordinated and form an As2O7 group. The MoVI atom is displaced from the center of an octahedron of O atoms. Two Na+ cations are disordered about inversion centres. Structural relationships between different compounds: A2MoO2As2O7 (A = K, Rb, AMOP2O7 (A = Na, K, Rb; M = Mo, Nb and MoP2O7 are discussed.

  13. New metal-organic frameworks of [M(C6H5O7)(C6H6O7)(C6H7O7)(H2O)] . H2O (M=La, Ce) and [Ce2(C2O4)(C6H6O7)2] . 4H2O

    International Nuclear Information System (INIS)

    Weng Shengfeng; Wang, Yun-Hsin; Lee, Chi-Shen

    2012-01-01

    Two novel materials, [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2), with a metal-organic framework (MOF) were prepared with hydrothermal reactions and characterized with photoluminescence, magnetic susceptibility, thermogravimetric analysis and X-ray powder diffraction in situ. The crystal structures were determined by single-crystal X-ray diffraction. Compound 1 crystallized in triclinic space group P1-bar (No. 2); compound 2 crystallized in monoclinic space group P2 1 /c (No. 14). The structure of 1 is built from a 1D MOF, composed of deprotonated citric ligands of three kinds. Compound 2 contains a 2D MOF structure consisting of citrate and oxalate ligands; the oxalate ligand arose from the decomposition in situ of citric acid in the presence of Cu II ions. Photoluminescence spectra of compounds 1b and 2 revealed transitions between the 5d 1 excited state and two levels of the 4f 1 ground state ( 2 F 5/2 and 2 F 7/2 ). Compounds 1b and 2 containing Ce III ion exhibit a paramagnetic property with weak antiferromagnetic interactions between the two adjacent magnetic centers. - Graphical Abstract: [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2)—with 1D and 2D structures were synthesized and characterized. Highlights: ► Two MOF – [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2) – with 1D and 2D structures. ► The adjacent chains of the 1D framework were correlated with each other through an oxalate ligand to form a 2D layer structure. ► The source of the oxalate ligand was the decomposition in situ of citric acid oxidized in the presence of Cu II ions.

  14. Uptake of CrO42- ions by Fe-treated tri-calcium phosphate

    International Nuclear Information System (INIS)

    Serrano G, J.; Ramirez S, J. L.; Bonifacio M, J.; Granados C, F.; Badillo A, V. E.

    2010-01-01

    CrO 4 2- ion adsorption of Fe-treated tri-calcium phosphate was studied by batch experiments as a function of contact time, initial concentration of metal ion and temperature. Adsorption results showed that at ph 5.5 and 1.0 x 10 -4 M chromium concentration the adsorption capacity of Fe-treated tri-calcium phosphate for CrO 4 2- ions was 7.10 x 10 -3 mmol/g. Chromium adsorption data on Fe-treated tri-calcium phosphate at various initial concentration fitted the Freundlich isotherm. By temperature studies the thermodynamic parameters ΔH 0 , ΔG 0 and ΔS 0 were estimated and the obtained results showed that the adsorption reaction was endothermic and spontaneous. (Author)

  15. Radiation damage produced by swift heavy ions in rare earth phosphates

    Energy Technology Data Exchange (ETDEWEB)

    Romanenko, Anton

    2017-02-13

    This work is devoted to the study of radiation damage produced by swift heavy ions in rare earth phosphates, materials that are considered as perspective for radioactive waste storage. Single crystals of rare earth phosphates were exposed to 2.1 GeV gold (Au) and 1.5 GeV xenon (Xe) ions of and analyzed mainly by Raman spectroscopy. All phosphates were found almost completely amorphous after the irradiation by 2.1 GeV Au ions at a fluence of 1 x 10{sup 13} ions/cm{sup 2}. Radiation-induced changes in the Raman spectra include the intensity decrease of all Raman bands accompanied by the appearance of broad humps and a reduction of the pronounced luminescence present in virgin samples. Analyzing the Raman peak intensities as a function of irradiation fluence allowed the calculation of the track radii for 2.1 GeV Au ions in several rare earth phosphates, which appear to be about 5.0 nm for all studied samples. Series of samples were studied to search for a trend of the track radius depending on the rare earth element (REE) cation. Among the monoclinic phosphates both Raman and small-angle X-ray scattering (SAXS) suggest no significant change of the track radius with increasing REE mass. In contrast, within the tetragonal phosphates Raman spectroscopy data suggests a possible slight decreasing trend of the track radius with the increase of REE atomic number. That finding, however, requires further investigation due to the low reliability of the qualitative Raman analysis. Detailed analysis of Raman spectra in HoPO{sub 4} showed the increase of peak width at the initial stage of the irradiation and subsequent decrease to a steady value at higher fluences. This observation suggested the existence of a defect halo around the amorphous tracks in HoPO{sub 4}. Raman peaks were found to initially shift to lower wavenumbers with reversing this trend at the fluence of 5 x 10{sup 11} for NdPO{sub 4} and 1 x 10{sup 12} ions/cm{sup 2} for HoPO{sub 4}. At the next fluence steps

  16. Thermal expansion and conductivity of RE2Sn2O7 (RE = La, Nd, Sm, Gd, Er and Yb) pyrochlores

    International Nuclear Information System (INIS)

    Feng, J.; Xiao, B.; Zhou, R.; Pan, W.

    2013-01-01

    Graphical abstract: Calculated cohesive energies and formation enthalpies of RE 2 Sn 2 O 7 compounds. The formation enthalpies at 298 K are more close to the experimental values. -- The calculated cohesive energies and formation enthalpies of Rare earth stannate (RE 2 Sn 2 O 7 ) compounds are in good agreement with the corresponding experimental values. The thermal expansion coefficients (TECs) of rare earth stannates are 7–9 × 10 −6 K −1 at high temperature. The results show that local spin density approximation predicts smaller TECs than the real values. The computed thermal conductivity of RE 2 Sn 2 O 7 is 1.8–2.5 W (m · K) −1 at 1273 K using the Slack–Clarke model, indicating that RE 2 Sn 2 O 7 compounds exhibit good thermal insulating properties at high temperature

  17. Synthesis and characterization of niobium and iron phosphate glasses for U3O8 immobilization

    International Nuclear Information System (INIS)

    Ghussn, Luciana

    2005-01-01

    Niobium and iron phosphate glasses were produced by melting inorganic compound mixtures in electric furnaces and microwave ovens. The chemical durability was compared among niobium phosphate glasses produced by both processes, and equivalent results were obtained. Leaching tests were also performed to compare the chemical durability among monolithic glass blocks and sintered glasses. The glass transition, crystallization and melting temperatures as well the Hruby parameter (K H ) and the activation energy for crystallization were determined from differential thermal analysis of niobium phosphate glasses produced in electric furnaces. Niobium phosphate glasses are thermally more stable (K H =0.82 +- 0.04) than iron phosphate glasses (K H = 0.42 +- 0.03). Sintered glasses were produced from particles with different particle size distributions and sintering temperatures in the range of 720 - 800 deg C for niobium phosphate and 530 - 680 deg C for iron phosphate glasses. The sintering process was suitable because a glass with composition 37P 2 O 5 -23K 2 O-40Nb 2 O 5 showing leaching rate of 10 -6 g.cm -2 .d -1 , 99 % of the monolithic density and none crystalline phases was obtained. This glass only crystallizes itself after re heating at temperatures above 800 deg C , showing two crystalline phases identified as KNb 3 O 8 e K 3 NbP 2 O 9 . The activation energies for crystallization are 496 +- 7 kJ/mol and 513 +- 14 kJ/mol. Niobium phosphate sintered glasses are better densified than sintered iron phosphate glasses. The leaching rate of sintered glasses that show open porosity is higher than monolithic glass blocks. This effect is related to an increase of the surface area associated to open porous and, a correction of the value of the surface area used to calculate the leaching rate is required. A model was proposed based on the surface area of spherical porous to take in account that effect. Even after correcting the surface area, the leaching rates of sintered

  18. The structural response of gadolinium phosphate to pressure

    International Nuclear Information System (INIS)

    Heffernan, Karina M.; Ross, Nancy L.; Spencer, Elinor C.; Boatner, Lynn A.

    2016-01-01

    Accurate elastic constants for gadolinium phosphate (GdPO 4 ) have been measured by single-crystal high-pressure diffraction methods. The bulk modulus of GdPO 4 determined under hydrostatic conditions, 128.1(8) GPa (K′=5.8(2)), is markedly different from that obtained with GdPO 4 under non-hydrostatic conditions (160(2) GPa), which indicates the importance of shear stresses on the elastic response of this phosphate. High pressure Raman and diffraction analysis indicate that the PO 4 tetrahedra behave as rigid units in response to pressure and that contraction of the GdPO 4 structure is facilitated by bending/twisting of the Gd–O–P links that result in increased distortion in the GdO 9 polyhedra. - Graphical abstract: A high-pressure single crystal diffraction study of GdPO 4 with the monazite structure is presented. The elastic behaviour of rare-earth phosphates are believed to be sensitive to shear forces. The bulk modulus of GdPO 4 measured under hydrostatic conditions is 128.1(8) GPa. Compression of the structure is facilitated by bending/twisting of the Gd−O−P links that result in increased distortion in the GdO 9 polyhedra. Display Omitted - Highlights: • The elastic responses of rare-earth phosphates are sensitive to shear forces. • The bulk modulus of GdPO 4 measured under hydrostatic conditions is 128.1(8) GPa. • Twisting of the inter-polyhedral links allows compression of the GdPO 4 structure. • Changes to the GdO 9 polyhedra occur in response to pressure (<7.0 GPa).

  19. Trace recovery of uranium and rare earth contained in phosphates by liquid-liquid extraction in sulfuric attack liquor

    International Nuclear Information System (INIS)

    Bousquet, F.; Foraison, D.; Leveque, A.; Sabot, J.L.

    1980-06-01

    Uranium and rare earths can be recovered in sedimentary phosphates during the wet processing of the ore by sulfuric acid giving raw phosphoric acid at 30 per cent of P 2 O 5 . Practically all the uranium contained and only part of rare earths are put into solution in this treatment. Separation of these elements in the phosphoric solution is obtained by liquid-liquid extraction with alkylphosphoric acids and especially with their mono and di esters. Partition isotherms are determined and counter-current tests are effected. Uranium and rare earths reextraction from these solvents can be simultaneous or separate with aqueous solutions alkaline or containing HF or by antisynergism. Pros and cons of each reextraction process are discussed. In conclusion HDEHP or OPPA are recommended because of availability, stability and hydrodynamic, OPPA less selective with rare earths allows the recovery with uranium of ceric earths, yttrium and yttric earths [fr

  20. Effect of rare-earth ion size on local electron structure in RBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (R = Tm, Dy, Gd, Eu, Nd and Y) superconductors: A positron study

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zhenping [Department of Technology and Physics, Zhengzhou University of Light Industry, 5 Dongfeng Road, Zhengzhou, Henan 450002 (China)]. E-mail: czhping@zzuli.edu.cn; Zhang Jincang [Department of Physics, Shanghai University, Shanghai 200436 (China); Su Yuling [Department of Technology and Physics, Zhengzhou University of Light Industry, 5 Dongfeng Road, Zhengzhou, Henan 450002 (China); Xue Yuncai [Department of Technology and Physics, Zhengzhou University of Light Industry, 5 Dongfeng Road, Zhengzhou, Henan 450002 (China); Cao Shixun [Department of Physics, Shanghai University, Shanghai 200436 (China)

    2006-02-15

    The effects of rare-earth ionic size on the local electron structure, lattice parameters and superconductivity have been investigated by positron annihilation technique (PAT) and related experiments for RBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (R = Tm, Dy, Gd, Eu, Nd and Y) superconductors. The local electron density n {sub e} is evaluated as a function of the rare-earth radius. The results show that both the bulk-lifetime {tau} {sub B} and the defect lifetime {tau} {sub 2} increase with increasing rare-earth ionic radius, while the local electron density n {sub e} decrease with increasing rare-earth ionic radius. These results prove that the changes of n {sub e}, the degree of orthorhombic distortion and the coupling between the Cu-O chains and the CuO{sub 2} planes all have an effect on the superconductivity of RBa{sub 2}Cu{sub 3}O{sub 7-{delta}} systems.

  1. The effect of lanthanides on color properties of the (Bi2O30.7(Ln2O30.3 compounds

    Directory of Open Access Journals (Sweden)

    Šulcová P.

    2008-01-01

    Full Text Available (Bi2O30.7(Ln2O30,3 solid solutions were synthesized as new inorganic yellow and orange pigments and their color properties have been investigated as possible ecological materials. The pigments were prepared by the solid state reaction of mixed oxides (Bi2O30.7(Ln2O30.3 of various rare earth cations (Ln = Eu, Gd, Tm, Yb and Lu. All the synthesized pigment samples were found to have color coordinates, low a* and high b* and exhibit the color from pale light yellow to orange. Reflectance spectra of the samples show high reflectance percentage in the 600 - 700 nm range. Characterization of the (Bi2O30.7(Ln2O30,3 solid solutions suggests that they have a potential to be alternative yellow colorants for paints, inks, plastics, and ceramics.

  2. Na3Co2(As0.52P0.48)O4(As0.95P0.05)2O7.

    Science.gov (United States)

    Ben Smida, Youssef; Guesmi, Abderrahmen; Zid, Mohamed Faouzi; Driss, Ahmed

    2013-11-30

    The title compound, trisodium dicobalt(II) (arsenate/phosphate) (diarsenate/diphosphate), was prepared by a solid-state reaction. It is isostructural with Na3Co2AsO4As2O7. The framework shows the presence of CoX22O12 (X2 is statistically disordered with As0.95P0.05) units formed by sharing corners between Co1O6 octa-hedra and X22O7 groups. These units form layers perpendicular to [010]. Co2O6 octa-hedra and X1O4 (X1 = As0.54P0.46) tetra-hedra form Co2X1O8 chains parallel to [001]. Cohesion between layers and chains is ensured by the X22O7 groups, giving rise to a three-dimensional framework with broad tunnels, running along the a- and c-axis directions, in which the Na(+) ions reside. The two Co(2+) cations, the X1 site and three of the seven O atoms lie on special positions, with site symmetries 2 and m for the Co, m for the X1, and 2 and m (× 2) for the O sites. One of two Na atoms is disordered over three special positions [occupancy ratios 0.877 (10):0.110 (13):0.066 (9)] and the other is in a general position with full occupancy. A comparison between structures such as K2CdP2O7, α-NaTiP2O7 and K2MoO2P2O7 is made. The proposed structural model is supported by charge-distribution (CHARDI) analysis and bond-valence-sum (BVS) calculations. The distortion of the coordination polyhedra is analyzed by means of the effective coordination number.

  3. The structural response of gadolinium phosphate to pressure

    Energy Technology Data Exchange (ETDEWEB)

    Heffernan, Karina M. [Department of Geosciences, Virginia Tech, Blacksburg, VA 24061 (United States); Ross, Nancy L., E-mail: nross@vt.edu [Department of Geosciences, Virginia Tech, Blacksburg, VA 24061 (United States); Spencer, Elinor C. [Department of Geosciences, Virginia Tech, Blacksburg, VA 24061 (United States); Boatner, Lynn A. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2016-09-15

    Accurate elastic constants for gadolinium phosphate (GdPO{sub 4}) have been measured by single-crystal high-pressure diffraction methods. The bulk modulus of GdPO{sub 4} determined under hydrostatic conditions, 128.1(8) GPa (K′=5.8(2)), is markedly different from that obtained with GdPO{sub 4} under non-hydrostatic conditions (160(2) GPa), which indicates the importance of shear stresses on the elastic response of this phosphate. High pressure Raman and diffraction analysis indicate that the PO{sub 4} tetrahedra behave as rigid units in response to pressure and that contraction of the GdPO{sub 4} structure is facilitated by bending/twisting of the Gd–O–P links that result in increased distortion in the GdO{sub 9} polyhedra. - Graphical abstract: A high-pressure single crystal diffraction study of GdPO{sub 4} with the monazite structure is presented. The elastic behaviour of rare-earth phosphates are believed to be sensitive to shear forces. The bulk modulus of GdPO{sub 4} measured under hydrostatic conditions is 128.1(8) GPa. Compression of the structure is facilitated by bending/twisting of the Gd−O−P links that result in increased distortion in the GdO{sub 9} polyhedra. Display Omitted - Highlights: • The elastic responses of rare-earth phosphates are sensitive to shear forces. • The bulk modulus of GdPO{sub 4} measured under hydrostatic conditions is 128.1(8) GPa. • Twisting of the inter-polyhedral links allows compression of the GdPO{sub 4} structure. • Changes to the GdO{sub 9} polyhedra occur in response to pressure (<7.0 GPa).

  4. Magnetic ordering in the rare earth iron germanates HoFeGe2O7 and ErFeGe2O7

    DEFF Research Database (Denmark)

    Cascales, C.; Puebla, E.G.; Klimin, S.

    1999-01-01

    RFeGe2O7 (R = Ho, Er) have been prepared in polycrystalline form, and their crystal structures have been refined from room-temperature high-resolution neutron diffraction data by the Rietveld method. Both materials are isostructural, space group P2(1)/m (no. 11), Z = 4. The most interesting feature...

  5. Sonochemical precipitation of amorphous uranium phosphates from trialkyl phosphate solutions and their thermal conversion to UP2O7

    Czech Academy of Sciences Publication Activity Database

    Doroshenko, I.; Žurková, J.; Moravec, Z.; Bezdička, Petr; Pinkas, J.

    2015-01-01

    Roč. 26, SEP (2015), s. 157-162 ISSN 1350-4177 Institutional support: RVO:61388980 Keywords : Uranium * Phosphates * Sonochemistry * Nuclear waste * Trimethyl phosphate * Triethyl phosphate Subject RIV: CA - Inorganic Chemistry Impact factor: 4.556, year: 2015

  6. Investigation of chemical bond characteristics, thermal expansion coefficients and bulk moduli of alpha-R2MoO6 and R2Mo2O7 (R = rare earths) by using a dielectric chemical bond method.

    Science.gov (United States)

    Li, Huaiyong; Zhang, Siyuan; Zhou, Shihong; Cao, Xueqiang

    2009-09-01

    Theoretical researches are performed on the alpha-R2MoO6 (R = Y, Gd, Tb Dy, Ho, Er, Tm and Yb) and pyrochlore-type R2Mo2O7 (R = Y, Nd, Sm, Gd, Tb and Dy) rare earth molybdates by using chemical bond theory of dielectric description. The chemical bonding characteristics and their relationship with thermal expansion property and compressibility are explored. The calculated values of linear thermal expansion coefficient (LTEC) and bulk modulus agree well with the available experimental values. The calculations reveal that the LTECs and the bulk moduli do have linear relationship with the ionic radii of the lanthanides: the LTEC decreases from 6.80 to 6.62 10(-6)/K and the bulk modulus increases from 141 to 154 GPa when R goes in the order Gd, Tb Dy, Ho, Er, Tm, and Yb in the alpha-R2MoO6 series; while in the R2Mo2O7 series, the LTEC ranges from 6.80 to 6.61 10(-6)/K and the bulk modulus ranges from 147 to 163 GPa when R varies in the order Nd, Sm, Gd, Tb and Dy. Copyright 2008 Wiley Periodicals, Inc.

  7. The influence of SrO and CaO in silicate and phosphate bioactive glasses on human gingival fibroblasts.

    Science.gov (United States)

    Massera, J; Kokkari, A; Närhi, T; Hupa, L

    2015-06-01

    In this paper, we investigate the effect of substituting SrO for CaO in silicate and phosphate bioactive glasses on the human gingival fibroblast activity. In both materials the presence of SrO led to the formation of a CaP layer with partial Sr substitution for Ca. The layer at the surface of the silicate glass consisted of HAP whereas at the phosphate glasses it was close to the DCPD composition. In silicate glasses, SrO gave a faster initial dissolution and a thinner reaction layer probably allowing for a continuous ion release into the solution. In phosphate glasses, SrO decreased the dissolution process and gave a more strongly bonded reaction layer. Overall, the SrO-containing silicate glass led to a slight enhancement in the activity of the gingival fibroblasts cells when compared to the SrO-free reference glass, S53P4. The cell activity decreased up to 3 days of culturing for all phosphate glasses containing SrO. Whereas culturing together with the SrO-free phosphate glass led to complete cell death at 7 days. The glasses containing SrO showed rapid cell proliferation and growth between 7 and 14 days, reaching similar activity than glass S53P4. The addition of SrO in both silicate and phosphate glasses was assumed beneficial for proliferation and growth of human gingival fibroblasts due to Sr incorporation in the reaction layer at the glass surface and released in the cell culture medium.

  8. Three new d10 transition metal selenites containing PO4 tetrahedron: Cd7(HPO4)2(PO4)2(SeO3)2, Cd6(PO4)1.34(SeO3)4.66 and Zn3(HPO4)(SeO3)2(H2O)

    Science.gov (United States)

    Ma, Yun-Xiang; Gong, Ya-Ping; Hu, Chun-li; Mao, Jiang-Gao; Kong, Fang

    2018-06-01

    Three new d10 transition metal selenites containing PO4 tetrahedron, namely, Cd7(HPO4)2(PO4)2(SeO3)2 (1), Cd6(PO4)1.34(SeO3)4.66 (2) and Zn3(HPO4)(SeO3)2(H2O) (3), have been synthesized by hydrothermal reaction. They feature three different structural types. Compound 1 exhibits a novel 3D network composed of 3D cadmium selenite open framework with phosphate groups filled in the 1D helical tunnels. The structure of compound 2 displays a new 3D framework consisted of 2D cadmium oxide layers bridged by SeO3 and PO4 groups. Compound 3 is isostructural with the reported solids of Co3(SeO3)3-x(PO3OH)x(H2O) when x is equal to 1.0. Its structure could be viewed as a 3D zinc oxide open skeleton with SeO3 and HPO4 polyhedra attached on the wall of the tunnels. They represent the only examples in metal selenite phosphates in addition to the above cobalt compounds. Optical diffuse reflectance spectra revealed that these solids are insulators, which are consistent with the results of band structure computations based on DFT algorithm.

  9. Investigations on the determination of traces of some rare earths (Eu, Sm, Gd, Y) in oxides of rare earths (Y2O3, Sm2O3, Gd2O3) by emission spectrography in d.c. arc

    International Nuclear Information System (INIS)

    Dittrich, K.; Gajek, M.; Luan, P.

    1978-01-01

    The evaporation of traces and matrices of rare earth elements was investigated in different atmospheres. It was found, that low-boiling rare earths elements, because of their extended formation of carbides evaporate more slowly than high-boiling rare earths elements. The evaporation of the traces depends on the matrices. 3 cases for the determination of traces of rare earths elements in oxides of other rare earths elements are derived from the results of the evaporation: Low- to high-boiling traces of rare earths elements in low-boiling matrices of rare earths elements, low-boiling traces in medium- to high-boiling matrices, and medium- to high-boiling traces in medium- to high-boiling matrices. The results of the determination are: in Y 2 O 3 : 14 ppm Sm, 2 ppm Eu; in Gd 2 O 3 : 18 ppm Y, 3 ppm Sm, 2 ppm Eu; in Sm 2 O 3 : 70 ppm Y, 370 ppm Gd, 16 ppm Eu. (author)

  10. Preparation and photocatalytic activity of chemically-bonded phosphate ceramics containing TiO2

    Science.gov (United States)

    Martins, Monize Aparecida; de Lima, Bruna de Oliveira; Ferreira, Leticia Patrício; Colonetti, Emerson; Feltrin, Jucilene; De Noni, Agenor

    2017-05-01

    Titanium dioxide was incorporated into chemically-bonded phosphate ceramic for use as photocatalytic inorganic coating. The coatings obtained were applied to unglazed ceramic tiles and cured at 350 °C. The surfaces were characterized by photocatalytic activity, determined in aqueous medium, based on the degradation of methylene blue dye. The effects of the percentage of TiO2 and the thickness of the layer on the photocatalytic efficiency were evaluated. The influence of the incorporation of TiO2 on the consolidation of the phosphate matrix coating was investigated using the wear resistance test. The crystalline phases of the coatings obtained were determined by XRD. The microstructure of the surfaces was analyzed by SEM. The thermal curing treatment did not cause a phase transition from anatase to rutile. An increase in the photocatalytic activity of the coating was observed with an increase in the TiO2 content. The dye degradation indices ranged from 14.9 to 44.0%. The photocatalytic efficiency was not correlated with the thickness of the coating layer deposited. The resistance to wear decreased with an increase in the TiO2 content. Comparison with a commercial photocatalytic ceramic coating indicated that there is a range of values for the TiO2 contents which offer potential for photocatalytic applications.

  11. Systems Li2B4O7 (Na2B4O7, K2B4O7)-N2H3H4OH-H2O at 25 deg C

    International Nuclear Information System (INIS)

    Skvortsov, V.G.; Sadetdinov, Sh.V.; Akimov, V.M.; Mitrasov, Yu.N.; Petrova, O.V.; Klopov, Yu.N.

    1994-01-01

    Phase equilibriums in the Li 2 B 4 O 7 (Na 2 B 4 O 7 , K 2 B 4 O 7 )-N 2 H 3 H 4 OH-H 2 O systems were investigated by methods of isothermal solubility, refractometry and PH-metry at 25 deg C for the first time. Lithium and sodium tetraborates was established to form phases of changed composition mM 2 B 4 O 7 ·nN 2 H 3 C 2 H 4 OH·XH 2 O, where M=Li, Na with hydrazine ethanol. K 2 B 4 O 7 ·4H 2 O precipitates in solid phase in the case of potassium salt. Formation of isomorphous mixtures was supported by X-ray diffraction and IR spectroscopy methods

  12. Photoluminescence properties of Er{sup 3+}-doped alkaline earth titanium phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Murthy, D.V.R.; Babu, A. Mohan [Department of Physics, Sri Venkateswara University, Tirupati 517 502 (India); Jamalaiah, B.C. [Department of Physics, Sree Vidyanikethan Engineering College, Tirupati, 517 102 (India); Moorthy, L. Rama, E-mail: lrmphysics@yahoo.co.i [Department of Physics, Sri Venkateswara University, Tirupati 517 502 (India); Jayasimhadri, M.; Jang, Kiwan; Lee, Ho Sueb [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Yi, Soung Soo [Department of Photonics, Silla University, Pusan 617-736 (Korea, Republic of); Jeong, Jung Hyun [Department of Physics, Pukyong National University, Pusan 608-737 (Korea, Republic of)

    2010-02-18

    Er{sup 3+}-doped alkaline earth titanium phosphate (RTP) glasses with molar composition of 24 (NaPO{sub 3}){sub 6} + 30 KH{sub 2}PO{sub 4} + 25 TiO{sub 2} + 20 RCl{sub 2} + 1 Er{sub 2}O{sub 3} were prepared by melt quenching technique. Judd-Ofelt intensity parameters ({Omega}{sub 2,4,6}) were determined from the experimental oscillator strengths (f{sub exp}) of absorption bands. From these parameters spontaneous emission probabilities (A{sub R}), luminescence branching ratios ({beta}{sub R}) and radiative lifetimes ({tau}{sub R}) have been calculated. Visible and near infrared photoluminescence spectra has been recorded by exciting the samples at 380 and 970 nm respectively. An intense broad emission band at 1.53 {mu}m was observed corresponding to {sup 4}I{sub 13/2} {yields} {sup 4}I{sub 15/2} transition. McCumber theory has been applied to determine the emission cross-sections ({sigma}{sub e}) of the {sup 4}I{sub 13/2} {yields} {sup 4}I{sub 15/2} transition using the absorption cross-sections ({sigma}{sub a}). The lifetimes of {sup 4}S{sub 3/2} level were measured for the glasses by exciting the samples at 540 nm wavelength and the quantum efficiencies were also determined.

  13. Raman and FTIR spectra of CeO{sub 2} and Gd{sub 2}O{sub 3} in iron phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Yuanming, E-mail: laiyuanming@ipm.com.cn [State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals, Kunming Institute of Precious Metals, Kunming 650106 (China); State Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Liang, Xiaofeng; Yang, Shiyuan [State Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Liu, Pei; Zeng, Yiming; Hu, Changyi [State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals, Kunming Institute of Precious Metals, Kunming 650106 (China)

    2014-12-25

    Highlights: • The structure of the studied samples has been investigated by Raman and FTIR spectroscopy. • The structure for the all samples has similar features. • The structure consists of predominantly Q{sup 1} with a fraction of Q{sup 0} and Q{sup 2} units. • The Ce and Gd enters in the structure of studied glasses as a network modifier. - Abstract: In the present work, multicomponent oxide samples of composition x(CeO{sub 2} + Gd{sub 2}O{sub 3})–(40 − x)Fe{sub 2}O{sub 3}–60P{sub 2}O{sub 5} (0 ⩽ x ⩽ 8 mol%) were produced by conventional melting method. The samples were investigated to examine the effect of the CeO{sub 2} and Gd{sub 2}O{sub 3} composition on the structure of the iron phosphate glasses system. The X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) for the x ⩽ 6 mol% samples show all the samples formed homogeneous glass, but for the x = 8 mol% samples show the presence of randomly distributed crystalline phase embedded in an amorphous matrix. The x(CeO{sub 2} + Gd{sub 2}O{sub 3})–(40 − x)Fe{sub 2}O{sub 3}–60P{sub 2}O{sub 5} glass containing 8 mol% CeO{sub 2} and Gd{sub 2}O{sub 3} partially crystallized during annealing and Ce/Gd-rich were identified by EDS in the crystalline phase. The structure of the studied samples has been investigated using Raman and Fourier transform infrared spectroscopy (FTIR). The Raman and FTIR spectra for the samples have analogous spectral features. The Raman and FTIR spectra suggest that the structure is mainly constituted by the pyrophosphate glass based structure, with a part proportion of metaphosphate and orthophosphate structure. Raman and FTIR spectra allowed us to identify the structural units which appear in the structural network of these phosphate glasses and also the network modifier role of cerium and gadolinium ions.

  14. Enhanced NH3 gas sensing performance based on electrospun alkaline-earth metals composited SnO2 nanofibers

    International Nuclear Information System (INIS)

    Xu, Shuang; Kan, Kan; Yang, Ying; Jiang, Chao; Gao, Jun; Jing, Liqiang; Shen, Peikang; Li, Li

    2015-01-01

    Highlights: • The small-sized SnO 2 (5–7 nm) were obtained by adding the alkaline-earth. • Sr-composited SnO 2 nanofibers showed uniform nanotubes structure (Sr/SnO 2 ). • Sr/SnO 2 showed an excellent sensing performance to NH 3 at room temperature. - Abstract: One-dimensional alkaline-earth metals composited SnO 2 (Ae/SnO 2 ) nanofibres were fabricated via electrospinning technique, followed by thermal treatment at 600 °C for 5 h. Transmission electron microscopy (TEM) studies showed that the nanoparticles size of Ae/SnO 2 was 5–7 nm, which was smaller than the pristine SnO 2 nanorods attached by 20 nm nanoparticles. Moreover, Sr/SnO 2 nanocomposites showed uniform nanotubes structure with the wall thickness of about 30 nm, in which all the nanoparticles were connected to their neighbors by necks. The Sr/SnO 2 nanotubes exhibited an excellent sensing response toward NH 3 gas at room temperature, lower detection limit (10 ppm), faster response time (6 s towards 2000 ppm∼16 s towards 10 ppm) and better reversibility compared to the pristine SnO 2 nanorods. The enhanced sensor performances were attributed to the higher conductivity of the Sr/SnO 2 . Mott–Schottky plots (M–S) and electrochemical impedance spectroscopy (EIS) measurements indicated that the carrier density of Sr/SnO 2 nanotubes was 3 fold of that pristine SnO 2

  15. Directly coupled direct current superconducting quantum interference device magnetometers based on ramp-edge Ag:YBa2Cu3O7-x/PrBa2Cu3O7-x/Ag:YBa2Cu3O7-x junctions

    International Nuclear Information System (INIS)

    Jia, Q.X.; Yan, F.; Mombourquette, C.; Reagor, D.

    1998-01-01

    Directly coupled dc superconducting quantum interference device (SQUID) magnetometers on LaAlO 3 substrates were fabricated using ramp-edge superconductor/normal-metal/superconductor junctions, where Ag-doped YBa 2 Cu 3 O 7-x was used for the electrode and PrBa 2 Cu 3 O 7-x for the normal-metal barrier. A flux noise of 8x10 -6 Φ 0 Hz -1/2 at 10 kHz measured with a dc bias current was achieved at 75 K, which corresponded to a field sensitivity of 400fTHz -1/2 for a magnetometer with a pick-up loop area of 8.5mmx7.5mm. Most significantly, the noise floor increased at lower frequencies with a frequency dependence slightly less than 1/f. The field noise of the SQUID magnetometers increased by only 25% after cycling the devices from zero field to 500 mG. In a static earth close-quote s magnetic field background, the field noise of the SQUID magnetometers increased by less than a factor of 2. copyright 1998 American Institute of Physics

  16. Rare earths (Ce, Eu, Tb) doped Y2Si2O7 phosphors for white LED

    International Nuclear Information System (INIS)

    Sokolnicki, Jerzy

    2013-01-01

    Nanocrystalline yttrium pyrosilicate Y 2 Si 2 O 7 (YPS) singly, doubly or triply doped with Ce 3+ , Eu 3+ , Tb 3+ was obtained by the reaction of nanostructured Y 2 O 3 :Ln 3+ and colloidal SiO 2 at high temperatures. X-ray diffraction analysis confirmed the formation of a single phase of α-YPS at 1200 °C. Two series of YPS samples doped with Eu 3+ or Eu 3+ /Tb 3+ were obtained by applying the reducing atmosphere (75%N 2 +25%H 2 ) at different temperatures. The luminescence and excitation spectra are reported. The singly Eu 3+ doped YPS emit from both Eu 3+ and Eu 2+ ions, with the spectral position and width of the Eu 2+ emission different in both series. The presence of Eu 2+ in the samples was confirmed by electron paramagnetic resonance (EPR) spectra. A broadband emission of Eu 2+ (380–650 nm), combined with the red emission of Eu 3+ is perceived by the naked eye as white light. Co-doping of YPS:Eu 3+ with Tb 3+ results in enhancement of the green component of the emission, and well-balanced white luminescence. The colour of this emission is tunable, and it is possible to get Commission International de I'Eclairage (CIE) chromaticity coordinates of (0.327, 0.327), colour-rendering index (CRI) of 85, and quantum efficiency (QE) of 71%. These phosphors are efficiently excited in the wavelength range of 300–420 nm, which perfectly matches a near UV-emitting InGaN chip. It was shown that for triply (Ce 3+ , Eu 3+ and Tb 3+ ) doped samples the three emissions from the particular activators can be generated using one excitation wavelength. The white light resulting from the superposition of the blue (Ce 3+ ), green (Tb 3+ ) and red (Eu 3+ ) emissions can be obtained by varying the concentration of the active ions and the treating atmosphere, i.e. reducing or oxidising. Eu 2+ was not detected in the triply doped samples, and hence line emissions mostly exhibit CRI values equal to or below 30. - Highlights: ► Nanocrystalline Y 2 Si 2 O 7 was obtained by the

  17. Lanthanide ions doped Y2Sn2O7 nano-particles: low temperature synthesis and photoluminescence study

    International Nuclear Information System (INIS)

    Nigam, Sandeep; Sudarsan, V.; Vatsa, R.K.

    2008-01-01

    During the past decade, pyrochlore-type oxides (A 2 B 2 O 7 ) have emerged as important host matrices for lanthanide doped luminescent materials due to their higher thermal stability. Up to now, conventional solid-state reaction is the most commonly used synthetic method for preparation, of rare-earth pyrochlore oxides. This synthesis route employs a solid-state reaction of metal-oxide with appropriate rare-earth oxides at high temperature (>1200 deg C) for a long time (several days). However, in present work, Y 2 Sn 2 O 7 nanoparticles co-doped with lanthanide ions Tb 3+ and Ce 3+ were prepared based on the urea hydrolysis of Y 3+ , Sn 4+ , and Ln 3+ in ethylene glycol medium at 150 deg C followed by heating at 500, 700 and 900 deg C

  18. Synthesis and characterization of insulin/zirconium phosphate@TiO2 hybrid composites for enhanced oral insulin delivery applications.

    Science.gov (United States)

    Safari, Mostafa; Kamari, Younes; Ghiaci, Mehran; Sadeghi-Aliabadi, Hojjat; Mirian, Mina

    2017-05-01

    In this work, a series of composites of insulin (Ins)/zirconium phosphate (ZrP) were synthesized by intercalation method, then, these composites were coated with TiO 2 by sol-gel method to prepare Ins/ZrP@TiO 2 hybrid composites and the drug release of the composites was investigated by using UV-Vis spectroscopy. Ins/ZrP (10, 30, 60 wt%) composites were prepared by intercalation of insulin into the ZrP layers in water. Then Ins/ZrP composites were coated with different amounts of TiO 2 (30, 50, 100 wt %) by using titanium tetra n-butoxide, as precursor. Formation of intercalated Ins/ZrP and Ins/ZrP@TiO 2 hybrid composites was characterized by FT-IR, FE-SEM, BET and XRD analysis. Zeta potential of the optimized Ins/ZrP@TiO 2 hybrid composite was determined -27.2 mV. Cytotoxic effects of the optimized Ins/ZrP@TiO 2 hybrid composite against HeLa and Hek293T cell lines were evaluated using MTT assay and the results showed that designed drug delivery system was not toxic in biological environment. Compared to the Ins/ZrP composites, incorporation of TiO 2 coating enhanced the drug entrapment considerably, and reduced the drug release. The Ins/ZrP composites without TiO 2 coating released the whole drug after 30 min in pH 7.4 (phosphate buffer solution) while the TiO 2 -coated composites released the entrapped drug after 20 h. In addition to increasing the shelf life of hormone, this nanoencapsulation and nanocoating method can convert the insulin utilization from injection to oral and present a painless and more comfortable treatment for diabetics.

  19. Insertion of water into rare earth oxocuprates (Ln)Ba 2Cu 3O 7

    Science.gov (United States)

    Günther, Wulf; Schöllhorn, Robert

    1996-02-01

    The solid state reaction of LnBa 2Cu 3O 7-δ bulk material with water vapour corresponds to a quantitative topotactic reaction of the solid with H 2O to a maximum stoichiometry of LnBa 2Cu 3O 7-δ(H 2O) 1. The reaction proceeds in a temperature window which depends upon the oxygen content (δ) of the starting phase and is correlated with a structural transition via intermediate states. Although the integral copper oxidation state is not affected by the water intercalation, electronic and transport properties are strongly influenced. The insertion of water into these defect perovskites has to be described as a topotactic acid/base process.

  20. Partition of rare-earths in phosphates laterites from Maicuru, Brazil - PA

    International Nuclear Information System (INIS)

    Lemos, V.P.; Costa, M.L. da.

    1987-01-01

    The phosphatic laterites of Maicuru-Para are formed of aluminium phosphates, mainly of the crandallite group, followed by wardite, augellite and senegallite. The crandallite group is represented in the form of the solid solution goyazite-florencite-crandallite, in variable proportions. In three samples, the florencite occurs as the predominant member, while in the others crandallite is the main mineral. The unit-cell dimension of florencites, in two samples, measured are the same as those of the florencites from other deposits. The rare earths occur mainly in this mineral group with predominance of the light rare earth elements. This is well observed in the condrite normalized REE patterns. These enrichments are not regular. The geochemical characteristics of the rare earth distribution in the crandallites of Maicuru, leads tho suggest this mineral was formed from distinct lithologies. (author) [pt

  1. Geochemical and rare earth elements distribution pattern in gaiman F M.phosphatic levels, Chubu t, Argentina

    International Nuclear Information System (INIS)

    Castro, L.; Fazio, A.; Tourn, S.; Scasso, R.

    2004-01-01

    Phosphatic concretions in the Early Miocene marine sediments of the Gaiman Formation (Miocene) were analyzed for rare earth elements (REE), in order to discuss their pattern in the context of paleoenvironmental interpretations. P2O5 in concretions is between 15,61 to 21,82%. Two types of concretions are found: Type 1 represented by in situ ones developed within transgressive-early highstand system tracts which shows little evidence for significant transportation, and Type 2 related to reworking, winnowing and mechanical concentration of resistant particles. Type 1 exhibits higher REE/P ratios and a significant enrichment in HREE than Type 2. The REE pattern in both shows a slight depletion in LREE with a weak Ce anomaly (-0.08 to 0.04), and an enrichment in high rare earth elements, in comparison to the a verage shale. Their mean content in REE (915 ppm) and Y (500 ppm) doubles the worldwide phosphorite average (462 ppm and 275 ppm). No significant correlation is found between REEs and P2O5. On the other hand, HREE enrichment (Lu/Ce) increases with the REEs bulk content. The pattern is consistent with shallow water inner shelf marine environment which is also suggested by sedimentological and paleontological evidence [es

  2. Spectroscopic and neutron detection properties of rare earth and titanium doped LiAlO 2 single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Dickens, Peter T.; Marcial, José; McCloy, John; McDonald, Benjamin S.; Lynn, Kelvin G.

    2017-10-01

    In this study, LiAlO2 crystals doped with rare-earth elements and Ti were produced by the CZ method and spectroscopic and neutron detection properties were investigated. Photoluminescence revealed no clear luminescent activation of LiAlO2 by the rare-earth dopants though some interesting luminescence was observed from secondary phases within the crystal. Gamma-ray pulse height spectra collected using a 137Cs source exhibited only a Compton edge for the crystals. Neutron modeling using Monte Carlo N-Particle Transport Code revealed most neutrons used in the detection setup are thermalized, and while using natural lithium in the crystal growth, which contains 7.6 % 6Li, a 10 mm Ø by 10 mm sample of LiAlO2 has a 70.7 % intrinsic thermal neutron capture efficiency. Furthermore, the pulse height spectra collected using a 241Am-Be neutron source demonstrated a distinct neutron peak.

  3. In situ DRIFTS investigation of NH3-SCR reaction over CeO2/zirconium phosphate catalyst

    Science.gov (United States)

    Zhang, Qiulin; Fan, Jie; Ning, Ping; Song, Zhongxian; Liu, Xin; Wang, Lanying; Wang, Jing; Wang, Huimin; Long, Kaixian

    2018-03-01

    A series of ceria modified zirconium phosphate catalysts were synthesized for selective catalytic reduction of NO with ammonia (NH3-SCR). Over 98% NOx conversion and 98% N2 selectivity were obtained by the CeO2/ZrP catalyst with 20 wt.% CeO2 loading at 250-425 °C. The interaction between CeO2 and zirconium phosphate enhanced the redox abilities and surface acidities of the catalysts, resulting in the improvement of NH3-SCR activity. The in situ DRIFTS results indicated that the NH3-SCR reaction over the catalysts followed both Eley-Rideal and Langmuir-Hinshelwood mechanisms. The amide (sbnd NH2) groups and the NH4+ bonded to Brønsted acid sites were the important intermediates of Eley-Rideal mechanism.

  4. Mutual effects of copper and phosphate on their interaction with γ-Al2O3: combined batch macroscopic experiments with DFT calculations.

    Science.gov (United States)

    Ren, Xuemei; Yang, Shitong; Tan, Xiaoli; Chen, Changlun; Sheng, Guodong; Wang, Xiangke

    2012-10-30

    The mutual effects of Cu(II) and phosphate on their interaction with γ-Al(2)O(3) are investigated by using batch experiments combined with density functional theory (DFT) calculations. The results of batch experiments show that coexisting phosphate promotes the retention of Cu(II) on γ-Al(2)O(3), whereas phosphate retention is not affected by coexisting Cu(II) at low initial phosphate concentrations (≤ 3.6 mg P/L). Cu-phosphate aqueous complexes control Cu(II) retention through the formation of type B ternary surface complexes (where phosphate bridges γ-Al(2)O(3) and Cu(II)) at pH 5.5. This deduction is further supported by the results of DFT calculations. More specifically, the DFT calculation results indicate that the type B ternary surface complexes prefer to form outer-sphere or monodentate inner-sphere binding mode under our experimental conditions. The enhancement of phosphate retention on γ-Al(2)O(3) in the presence of Cu(II) at high initial phosphate concentrations (>3.6 mg P/L) may be attributed to the formation of 1:2 Cu(II)-phosphate species and/or surface precipitates. Understanding the mutual effects of phosphate and Cu(II) on their mobility and transport in mineral/water environments is more realistic to design effective remediation strategies for reducing their negative impacts on aquatic/terrestrial environments. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Zoledronate complexes. III. Two zoledronate complexes with alkaline earth metals: [Mg(C(5)H(9)N(2)O(7)P(2))(2)(H(2)O)(2)] and [Ca(C(5)H(8)N(2)O(7)P(2))(H(2)O)](n).

    Science.gov (United States)

    Freire, Eleonora; Vega, Daniel R; Baggio, Ricardo

    2010-06-01

    Diaquabis[dihydrogen 1-hydroxy-2-(imidazol-3-ium-1-yl)ethylidene-1,1-diphosphonato-kappa(2)O,O']magnesium(II), [Mg(C(5)H(9)N(2)O(7)P(2))(2)(H(2)O)(2)], consists of isolated dimeric units built up around an inversion centre and tightly interconnected by hydrogen bonding. The Mg(II) cation resides at the symmetry centre, surrounded in a rather regular octahedral geometry by two chelating zwitterionic zoledronate(1-) [or dihydrogen 1-hydroxy-2-(imidazol-3-ium-1-yl)ethylidene-1,1-diphosphonate] anions and two water molecules, in a pattern already found in a few reported isologues where the anion is bound to transition metals (Co, Zn and Ni). catena-Poly[[aquacalcium(II)]-mu(3)-[hydrogen 1-hydroxy-2-(imidazol-3-ium-1-yl)ethylidene-1,1-diphosphonato]-kappa(5)O:O,O':O',O''], [Ca(C(5)H(8)N(2)O(7)P(2))(H(2)O)](n), consists instead of a Ca(II) cation in a general position, a zwitterionic zoledronate(2-) anion and a coordinated water molecule. The geometry around the Ca(II) atom, provided by six bisphosphonate O atoms and one water ligand, is that of a pentagonal bipyramid with the Ca(II) atom displaced by 0.19 A out of the equatorial plane. These Ca(II) coordination polyhedra are ;threaded' by the 2(1) axis so that successive polyhedra share edges of their pentagonal basal planes. This results in a strongly coupled rhomboidal Ca(2)-O(2) chain which runs along [010]. These chains are in turn linked by an apical O atom from a -PO(3) group in a neighbouring chain. This O-atom, shared between chains, generates strong covalently bonded planar arrays parallel to (100). Finally, these sheets are linked by hydrogen bonds into a three-dimensional structure. Owing to the extreme affinity of zoledronic acid for bone tissue, in general, and with calcium as one of the major constituents of bone, it is expected that this structure will be useful in modelling some of the biologically interesting processes in which the drug takes part.

  6. Retenção do fungicida triadimenol em latossolos em razão da calagem e da fosfatagem Retention of the fungicide triadimenol in Latosol due to lime and phosphate applications

    Directory of Open Access Journals (Sweden)

    Júlio César Azevedo Nóbrega

    2005-05-01

    Full Text Available O objetivo deste trabalho foi avaliar o efeito da calagem e da fosfatagem na retenção do triadimenol em um Latossolo Vermelho-Amarelo distrófico (LVAd e em um Latossolo Vermelho distrófico (LVd em microcolunas de solo. Calagem e fosfatagem, realizadas em conjunto, reduziram a retenção do produto nas amostras do LVAd (7,7% e 8,6%, respectivamente, para a dose de 2,67 e 10,68 kg ha-1 do princípio ativo. No LVd, a calagem e fosfatagem, quando realizadas isoladamente, causaram menor retenção do produto (calagem 7,2% e 3,9%, fosfatagem 10,1% e 6,8%, respectivamente, para as doses de 2,67 e 10,68 kg ha-1 em relação às amostras controle. Apesar da quantidade do produto na solução do solo ser inferior a 1% da dose aplicada, valores mais elevados do produto foram encontrados nas amostras de solo tratadas com calcário e fosfato, isoladamente ou não, no LVAd e, isoladamente, no LVd.The objective of this work was to evaluate the effect of liming and phosphate applications on the retention of triadimenol in microcolumns of soil material of a distrophic Red-Yellow Latosol (Typic Hapludox and a distrophic Red Latosol (Typic Hapludox. Lime and phosphate applications decreased retention of triadimenol on LVAd samples (7.7% and 8.6%, respectively, for 2.67 and 10.68 kg ha-1 of the active principle. Lower retention of triadimenol was observed on LVd samples when lime and phosphate were applied separately (liming 7.2% and 3.9%, phosphate fertilization 10.1% and 6.8%, respectively, for 2.67 and 10.68 kg ha-1 of the compound. In spite of the amount of the chemical in soil solution being inferior to 1% of the dose applied, higher values of the chemical were found in the samples with lime and phosphate, singly or not in the LVAd and singly in the LVd.

  7. Hydrogen permeation resistant phosphate coatings

    International Nuclear Information System (INIS)

    McGuire, J.C.

    1979-01-01

    A method for reducing hydrogen diffusion through metal is described. The metal is coated with a phosphate-radical-containing, phosphate-glass-forming material on at least one surface. The coating is then heated to at least 350 0 C to form a phosphate glass. This method is especially applicable to nuclear reactors to minimize tritium diffusion. The coating is preferably formed with a solution of phosphoric acid which may also contain compounds such as MnSO 4 , SiO 2 and Na 2 Cr 2 O 7 . (author)

  8. Phosphate Changes Effect of Humic Acids on TiO2 Photocatalysis: From Inhibition to Mitigation of Electron-Hole Recombination.

    Science.gov (United States)

    Long, Mingce; Brame, Jonathon; Qin, Fan; Bao, Jiming; Li, Qilin; Alvarez, Pedro J J

    2017-01-03

    A major challenge for photocatalytic water purification with TiO 2 is the strong inhibitory effect of natural organic matter (NOM), which can scavenge photogenerated holes and radicals and occlude ROS generation sites upon adsorption. This study shows that phosphate counteracts the inhibitory effect of humic acids (HA) by decreasing HA adsorption and mitigating electron-hole recombination. As a measure of the inhibitory effect of HA, the ratios of first-order reaction rate constants between photocatalytic phenol degradation in the absence versus presence of HA were calculated. This ratio was very high, up to 5.72 at 30 mg/L HA and pH 4.8 without phosphate, but was decreased to 0.76 (5 mg/L HA, pH 8.4) with 2 mM phosphate. The latter ratio indicates a surprising favorable effect of HA on TiO 2 photocatalysis. FTIR analyses suggest that this favorable effect is likely due to a change in the conformation of adsorbed HA, from a multiligand exchange arrangement to a complexation predominantly between COOH groups in HA and the TiO 2 surface in the presence of phosphate. This configuration can reduce hole consumption and facilitate electron transfer to O 2 by the adsorbed HA (indicated by linear sweep voltammetry), which mitigates electron-hole recombination and enhances contaminant degradation. A decrease in HA surface adsorption and hole scavenging (the predominant inhibitory mechanisms of HA) by phosphate (2 mM) was indicated by a 50% decrease in the photocatalytic degradation rate of HA and 80% decrease in the decay rate coefficient of interfacial-related photooxidation in photocurrent transients. These results, which were validated with other compounds (FFA and cimetidine), indicate that anchoring phosphate - or anions that exert similar effects on the TiO 2 surface - might be a feasible strategy to counteract the inhibitory effect of NOM during photocatalytic water treatment.

  9. Structural, optical and spectroscopical investigations into rare-earths perowskites RGaO3 (R=La, Pr, Nd) and NdBa-2Cu3O7

    International Nuclear Information System (INIS)

    Marti, W.

    1995-07-01

    In this work I was engaged in rare-earth perovskites. Primarily I investigated the structure of the rare-earth gallates RGaO 3 (R=La, Pr, Nd) as a function of the temperature by means of neutron diffraction and x-ray diffraction. As the high-T c superconductors these compounds belong to the family of the perovskites, they are ferroelastic and centro-symmetric. Because of the lanthanide-contraction all lattice constants and distortion parameters change systematically. The rare-earth-gallates RGaO 3 (R=La, Pr, Nd) are promising substrates for epitaxy of high-T c superconductors like RBa 2 Cu 3 OO 7-δ because of their structure parameters and expansion coefficients. I succeeded in producing plane-parallel single-domain crystals by means of uniaxial stress. The first order phase transition was observable only in LaGaO 3 . A structurally phase transition from orthorhombic to rhombohedral symmetry (high-temperature phase) occurs at 423 K. The hysteresis of the phase transition temperature of about 1.5 K was measured with single-domain crystals by means of neutron diffraction and polarized light microscopy. In NdGaO 3 we determined the long-range, three-dimensional, antiferromagnetic ordering of the Nd 3+ -ions below the ordering temperature at T N =0.97 K by means of magnetic neutron diffraction. The spin configuration could be described by a (--c z )-mode. Measurements of the magnetic susceptibility confirm the easy direction of magnetization to be the c-axis. Below 300mK an additional nuclear spin polarization due to the hyperfine-interaction appears parallel to the electronic spins, which amounts to 70% at 10mK. Further I investigated the optical properties of the rare-earth gallates. The birefringence of plane-parallel, polished single-domain crystals with thickness up to 300 μm was measured by means of orthoscopy and conoscopy. (author) figs., tabs., refs

  10. Ion-irradiation-induced phase transformation in rare earth sesquioxides (Dy2O3,Er2O3,Lu2O3)

    International Nuclear Information System (INIS)

    Tang, M.; Lu, P.; Valdez, J.A.; Sickafus, K.E.

    2006-01-01

    Polycrystalline pellets of cubic C-type rare earth structure (Ia3) Dy 2 O 3 , Er 2 O 3 , and Lu 2 O 3 were irradiated at cryogenic temperature (120 K) with 300 keV Kr ++ ions to a maximum fluence of 1x10 20 Kr/m 2 . Irradiated specimens were examined using grazing incidence x-ray diffraction and transmission electron microscopy. Ion irradiation leads to different radiation effects in these three materials. First, Dy 2 O 3 begins to transform to a monoclinic B-type rare earth structure (C2/m) at a peak dose of ∼5 displacements per atom (dpa) (corresponding to a fluence of 2x10 19 Kr/m 2 ). This transformation is nearly complete at a peak dose of 25 dpa (a fluence of 1x10 20 Kr/m 2 ). Er 2 O 3 also transforms to the B-type structure, but the transformation starts at a higher irradiation dose of about 15-20 dpa [a fluence of about (6-8)x10 19 Kr/m 2 ]. Lu 2 O 3 was found to maintain the C-type structure even at the highest irradiation dose of 25 dpa (a fluence of 1x10 20 Kr/m 2 ). No C-to-B transformation was observed in Lu 2 O 3 . The irradiation dose dependence of the C-to-B phase transformation observed in Dy 2 O 3 , Er 2 O 3 , and Lu 2 O 3 is closely related to the temperature dependence of the C-to-B phase transformation found in phase diagrams for these three materials

  11. Rare earth elements in the phosphatic-enriched sediment of the Peru shelf

    Science.gov (United States)

    Piper, D.Z.; Baedecker, P.A.; Crock, J.G.; Burnett, W.C.; Loebner, B.J.

    1988-01-01

    Apatite-enriched materials from the Peru shelf have been analyzed for their major oxide and rare earth element (REE) concentrations. The samples consist of (1) the fine fraction of sediment, mostly clay material, (2) phosphatic pellets and fish debris, which are dispersed throughout the fine-grained sediment, (3) tabular-shaped phosphatic crusts, which occur within the uppermost few centimeters of sediment, and (4) phosphatic nodules, which occur on the seafloor. The bulk REE concentrations of the concretions suggest that these elements are partitioned between the enclosed detrital material and the apatite fraction. Analysis of the fine-grained sediment with which the samples are associated suggested that this detrital fraction in the concretions should have shale REE values; the analysis of the fish debris suggested that the apatite fraction might have seawater values. The seawater contribution of REE's is negligible in the nodules and crust, in which the apatite occurs as a fine-grained interstitial cement. That is, the concentration of REE's and the REE patterns are predominantly a function of the amount of enclosed fine-grained sediment. By contrast, the REE pattern of the pelletal apatite suggests a seawater source and the absolute REE concentrations are relatively high. The REE P2O5 ratios of the apatite fraction of these samples thus vary from approximately zero (in the case of the crust and nodules) to as much as approximately 1.2 ?? 10-3 (in the case of the pellets). The range of this ratio suggests that rather subtle variations in the depositional environment might cause a significant variation in the REE content of this authigenic fraction of the sediment. Pelletal glauconite was also recovered from one sediment core. Its REE concentrations closely resemble those of the fish debris. ?? 1988.

  12. First-principles study on cubic pyrochlore iridates Y2Ir2O7 and Pr2Ir2O7

    International Nuclear Information System (INIS)

    Ishii, Fumiyuki; Mizuta, Yo Pierre; Kato, Takehiro; Ozaki, Taisuke; Weng Hongming; Onoda, Shigeki

    2015-01-01

    Fully relativistic first-principles electronic structure calculations based on a noncollinear local spin density approximation (LSDA) are performed for pyrochlore iridates Y 2 Ir 2 O 7 and Pr 2 Ir 2 O 7 . The all-in, all-out antiferromagnetic (AF) order is stablized by the on-site Coulomb repulsion U > U c in the LSDA+U scheme, with U c ∼ 1.1 eV and 1.3 eV for Y 2 Ir 2 O 7 and Pr 2 Ir 2 O 7 , respectively. AF semimetals with and without Weyl points and then a topologically trivial AF insulator successively appear with further increasing U. For U = 1.3 eV, Y 2 Ir 2 O 7 is a topologically trivial narrow-gap AF insulator having an ordered local magnetic moment ∼0.5μ B /Ir, while Pr 2 Ir 2 O 7 is barely a paramagnetic semimetal with electron and hole concentrations of 0.016/Ir, in overall agreements with experiments. With decreasing oxygen position parameter x describing the trigonal compression of IrO 6 octahedra, Pr 2 Ir 2 O 7 is driven through a non-Fermi-liquid semimetal having only an isolated Fermi point of Γ 8 + , showing a quadratic band touching, to a Z 2 topological insulator. (author)

  13. Stability of fluorite-type La{sub 2}Ce{sub 2}O{sub 7} under extreme conditions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, F.X., E-mail: zhangfx@umich.edu [Department of Earth and Environmental Sciences, The University of Michigan, Ann Arbor, MI 48109 (United States); State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao, Hebei 066004 (China); Tracy, C.L. [Department of Materials Science and Engineering, The University of Michigan, Ann Arbor, MI 48109 (United States); Lang, M. [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37966 (United States); Ewing, R.C. [Department of Geological Sciences, Stanford University, Stanford, CA 94305 (United States)

    2016-07-25

    The structural stability of fluorite-type La{sub 2}Ce{sub 2}O{sub 7} was studied at pressure up to ∼40 GPa and under hydrothermal conditions of ∼1 GPa and up to 350 °C, respectively, using synchrotron X-ray diffraction (XRD) and Raman scattering measurements. XRD measurements indicated that the fluorite-type La{sub 2}Ce{sub 2}O{sub 7} is not stable at pressures greater than 22.6 GPa and gradually transformed to a high-pressure phase. The high-pressure phase is not stable and changed back to the fluorite-type structure when pressure is released. The La{sub 2}Ce{sub 2}O{sub 7} fluorite is also not stable under hydrothermal conditions and began to react with water at 200–250 °C. Both Raman and XRD results suggest that lanthanum hydroxide La(OH){sub 3} and La{sup 3+}-doped CeO{sub 2} fluorite are the dominant products after hydrothermal treatment. - Graphical abstract: The fluorite-type La{sub 2}Ce{sub 2}O{sub 7} reacted with water at hydrothermal condition (1 GPa, and above 200 °C), and formed rare earth hydroxides. - Highlights: • La{sub 2}Ce{sub 2}O{sub 7} transforms to a metastable phase at pressure higher than 21 GPa. • La{sub 2}Ce{sub 2}O{sub 7} reacts with water at ∼1 GPa and above 200 °C. • The pressure-induced phase transition is reversible.

  14. Synthesis and physicochemical study of rare earth complexes with o-hydroxyphenoxymethylphosphonic acid

    International Nuclear Information System (INIS)

    Alibaeva, Z.M.; Snezhko, N.I.; Pechurova, N.I.; Martynenko, L.I.; Alekseeva, N.A.; Bovin, A.N.

    1987-01-01

    Rare earth complexes with o-hydroxyphenoxymethylphosphonic acid (C 7 H 9 PO 5 , N 2 L) of the HMl 2 xnH 2 O composition are synthesized. The compounds separated are studied by IR spectroscopy, X-ray phase and elementary analysis methods. The data obtained permit to suppose on the polymer structure of rare earth complexes, except HLaL 2 x2H 2 O which is evidently of the island structure

  15. A new continuous two-step molecular precursor route to rare-earth oxysulfides Ln2O2S

    International Nuclear Information System (INIS)

    De Crom, N.; Devillers, M.

    2012-01-01

    A continuous two-step molecular precursor pathway is designed for the preparation of rare-earth oxysulfides Ln 2 O 2 S (Ln=Y, La, Pr, Nd, Sm–Lu). This new route involves a first oxidation step leading to the rare-earth oxysulfate Ln 2 O 2 SO 4 which is subsequently reduced to the rare-earth oxysulfide Ln 2 O 2 S by switching to a H 2 –Ar atmosphere. The whole process occurs at a temperature significantly lower than usual solid state synthesis (T≤650 °C) and avoids the use of dangerous sulfur-based gases, providing a convenient route to the synthesis of the entire series of Ln 2 O 2 S. The molecular precursors consist in heteroleptic dithiocarbamate complexes [Ln(Et 2 dtc) 3 (phen)] and [Ln(Et 2 dtc) 3 (bipy)] (Et 2 dtc=N,N-diethyldithiocarbamate; phen=1,10-phenanthroline; bipy=2,2′-bipyridine) and were synthesized by a new high yield and high purity synthesis route. The nature of the molecular precursor determines the minimum synthesis temperature and influences therefore the purity of the final Ln 2 O 2 S crystalline phase. - Graphical abstract: A continuous two-step molecular precursor pathway was designed for the preparation of rare-earth oxysulfides Ln 2 O 2 S (Ln=Y, La, Pr, Nd, Sm–Lu), starting from heteroleptic dithiocarbamate complexes. The influence of the nature of the molecular precursor on the minimum synthesis temperature and on the purity of the final Ln 2 O 2 S crystalline phase is discussed. Highlights: ► A new high yield and high purity synthesis route of rare earth dithiocarbamates is described. ► These compounds are used as precursors in a continuous process leading to rare-earth oxysulfides. ► The oxysulfides are obtained under much more moderate conditions than previously described.

  16. Phosphate removal from aqueous solutions using polyaniline/ Ni 0.5 Zn 0.5 Fe 2 O 4 magnetic nanocomposite

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Tarmahi

    2017-05-01

    Full Text Available Background: Phosphorus is an indispensable element for the growth of animals and plants. There are several environmental problems related to phosphate; therefore, the technical and economic methods of removing phosphate are of great importance. This study evaluated the efficiency of polyaniline/ Ni0.5Zn0.5Fe2O4 magnetic nanocomposite in removing phosphate from aqueous environments. Methods: The adsorbent was characterized by several methods, including X-ray diffraction (XRD, scanning electron microscopy (SEM, vibrating sample magnetometer (VSM, and Fourier transform infrared (FT-IR spectroscopy. Then, the potential of the adsorbentto adsorb phosphate was investigated. The effects of the parameters of contact time (5-60 minutes, pH (3-9, adsorbent dosage (0.05-0.6 g, and initial phosphate concentration (2-100 mg/L on the phosphate removal yield were studied. All phosphate ion concentrations were measured using the ammonium molybdate spectrophotometric method. Results: The results showed that a time of 30 minutes, pH of 5, and adsorbent dose of 0.4 g were the optimum conditions for phosphate removal through adsorption. Increasing the initial concentration of phosphate from 2 to 100 mg/L decreased the removal efficiency from 90.3% to 32%. The experimental data was fitted well with the Freundlich isotherm model (R2 = 0.997. Conclusion: Polyaniline/Ni0.5Zn0.5Fe2O4 magnetic nanocomposite removes phosphate from aqueous solutions with a simple and environmentally benign procedure. The maximum adsorption capacity based on Langmuir isotherm (R2 = 0.931 is 85.4 mg/g. This magnetic nanocomposite is applicable in managing water resource pollution caused by phosphate ions.

  17. Glucose-6-phosphate dehydrogenase deficiency does not increase the susceptibility of sperm to oxidative stress induced by H2O2.

    Science.gov (United States)

    Roshankhah, Shiva; Rostami-Far, Zahra; Shaveisi-Zadeh, Farhad; Movafagh, Abolfazl; Bakhtiari, Mitra; Shaveisi-Zadeh, Jila

    2016-12-01

    Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common human enzyme defect. G6PD plays a key role in the pentose phosphate pathway, which is a major source of nicotinamide adenine dinucleotide phosphate (NADPH). NADPH provides the reducing equivalents for oxidation-reduction reductions involved in protecting against the toxicity of reactive oxygen species such as H 2 O 2 . We hypothesized that G6PD deficiency may reduce the amount of NADPH in sperms, thereby inhibiting the detoxification of H 2 O 2 , which could potentially affect their motility and viability, resulting in an increased susceptibility to infertility. Semen samples were obtained from four males with G6PD deficiency and eight healthy males as a control. In both groups, motile sperms were isolated from the seminal fluid and incubated with 0, 10, 20, 40, 60, 80, and 120 µM concentrations of H 2 O 2 . After 1 hour incubation at 37℃, sperms were evaluated for motility and viability. Incubation of sperms with 10 and 20 µM H 2 O 2 led to very little decrease in motility and viability, but motility decreased notably in both groups in 40, 60, and 80 µM H 2 O 2 , and viability decreased in both groups in 40, 60, 80, and 120 µM H 2 O 2 . However, no statistically significant differences were found between the G6PD-deficient group and controls. G6PD deficiency does not increase the susceptibility of sperm to oxidative stress induced by H 2 O 2 , and the reducing equivalents necessary for protection against H 2 O 2 are most likely produced by other pathways. Therefore, G6PD deficiency cannot be considered as major risk factor for male infertility.

  18. Synthesis, characterization, electrochemical investigation and antioxidant activities of a new hybrid cyclohexaphosphate: Cu1.5Li(C2H10N2)P6O18·7H2O

    Science.gov (United States)

    Sleymi, Samira; Lahbib, Karima; Rahmouni, Nihed; Rzaigui, Mohamed; Besbes-Hentati, Salma; Abid, Sonia

    2017-09-01

    A new organic-inorganic hybrid transition metal phosphate, Cu1.5Li(C2H10N2)P6O18·7H2O, has been prepared and characterized by X-ray diffraction, spectroscopy (infrared, Raman, diffuse reflectance and UV-Vis) and thermal analysis (TG). In addition, its electrochemical behaviors, as well as its antioxidant and antibacterial activities, have been investigated. Its structure is built up by the alternate linkages between copper and phosphate polyhedra, forming puckered layers with intersecting 12-membered rings, in which the ethylenediammonium cations reside. This compound is the first framework structure constructed from cyclohexaphosphates and three distinct copper cations. Cyclic voltammetry study in an acetonitrile solution reveals the facile anodic oxidation of its organic part on a platinum disk and a progressive growing of a thin film, though the repetitive cycling of potential. The title compound was tested for its in vitro antioxidant activities by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), Ferrous chelating ability (FIC) and Ferric Reducing Power (FRP) methods. The antioxidant activity of Cu1.5Li(C2H10N2)P6O18·7H2O was analyzed simultaneously with its antibacterial capacity against Escherichia coli, Salmonella typhimurium, Staphylococus aureus, Enterococcus feacium, Streptococcus agalactiae and Candida albicans. The tested compound showed significant antioxidant activities with low antibacterial properties.

  19. Synthesis and thermic behaviour (stability and sintering) of rare earth ortho-phosphates

    International Nuclear Information System (INIS)

    Lucas, S.

    2003-04-01

    Rare earth ortho-phosphates, LnPO 4 ,nH 2 O (Ln = La, Ce or Y), were synthesized by precipitation in aqueous media. The effect of pH, temperature, reagents stoichiometry and ripening time on the chemical composition and the morphology of the precipitates have been precised. The study of the thermal behaviour showed the presence of meta-phosphates as a secondary phase in the temperature range 1000 C - 1400 C that was very detrimental to the sintering. It is removed by calcining the powders at 1400 C. Thermogravimetry proved to be the best technique in order to insure the purity of the precipitates since it allows the detection of this phase down to a lower threshold than that associated with the other investigated characterization methods (IR or Raman spectrometry, chemical analysis, XRD, DTA). The monazites (La or Ce)PO 4 densify at 1400 C by natural sintering whereas the xenotime YPO 4 is not yet densified at 1500 C. Hot pressing at that temperature is required to its densification. The mechanical properties of the monazites remain low (sf about 120 MPa, K IC about 1.2 MPa.m 1/2 ). The xenotime ceramic is much more mechanically resistant (sf about 320 MPa, K IC about 1.5 MPa.m 1/2 ). An important acicular growth of the grains during the sintering of the xenotime (that occurs also during the synthesis process) is considered to be responsible for the behaviour and properties differences between this material and monazites. (author)

  20. Effect of B{sub 2}O{sub 3}/P{sub 2}O{sub 5} substitution on the properties and structure of tin boro-phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Saitoh, Akira, E-mail: asaito@ehime-u.ac.jp [Graduate School of Science and Engineering, Ehime University, Matsuyama, 3 Bunkyo-cho (Japan); Tricot, Grégory [LASIR UMR-CNRS 8516, Université de Lille 1, Villeneuve d' Ascq 59655 (France); UCCS UMR-CNRS 8181, Université de Lille 1, Villeneuve d' Ascq 59655 (France); Rajbhandari, Prashant [UCCS UMR-CNRS 8181, Université de Lille 1, Villeneuve d' Ascq 59655 (France); Anan, Shoji; Takebe, Hiromichi [Graduate School of Science and Engineering, Ehime University, Matsuyama, 3 Bunkyo-cho (Japan)

    2015-01-15

    Effect of B{sub 2}O{sub 3}/P{sub 2}O{sub 5} substitution on the properties and structure of the ternary 67SnO–(33–x)P{sub 2}O{sub 5}–xB{sub 2}O{sub 3} composition line (from x = 0–33 mol%) are examined in this contribution. We show that density and glass transition temperature increase while molar volume and thermal expansion coefficient decrease with increasing B{sub 2}O{sub 3} concentration. Density and thermal properties experience an original three-domain evolution with rapid (region I: 0 ≤ x < 5), substantial (II: 5 < x ≤ 15), and moderate (III: 15 < x ≤ 33) increase. In order to explain this unconventional behaviour, the glass structure has been investigated using high magnetic field 1 dimensional {sup 31}P and {sup 11}B MAS–NMR, micro-Raman and infrared spectroscopies. {sup 11}B MAS–NMR experiments allow to (i) monitor the 3- and 4-fold coordinated borate species proportion and (ii) highlight the presence of unreported 4-fold coordinated species in the region (III). Finally, it is shown that substitution of P{sub 2}O{sub 5} by B{sub 2}O{sub 3} induces an alteration of the dimeric phosphate network and formation of mixed anion structure that consists of Q{sup 0} phosphate units, 3- and 4-fold coordinated borate units and their combinations. - Highlights: • We examined B{sub 2}O{sub 3}/P{sub 2}O{sub 5} substitution effect on the ternary SnO–P{sub 2}O{sub 5}–B{sub 2}O{sub 3} glasses. • We show a three-domains evolution for density and thermal properties. • The structure was investigated by {sup 31}P and {sup 11}B NMR, Raman and IR spectroscopies. • 3 and 4-folded borate species and unreported 4-folded species are revealed. • Mixed anion structure consists of Q{sup 0} phosphate unit and 3- and 4-folded borate units.

  1. Luminescence properties of Eu2+ - activated alkaline-earth silicon-oxynitride MSi2O2-deltaN2+2/3delta (M = Ca, Sr, Ba) : A promising class of novel LED conversion phosphors

    NARCIS (Netherlands)

    Li, Y.Q.; Delsing, A.C.A.; With, de G.; Hintzen, H.T.J.M.

    2005-01-01

    The luminescence properties of Eu2+-activated alk.-earth Si-oxynitrides were studied. In the BaO-SiO2-Si3N4 system, a new BaSi2O2N2 compd. was obtained having the monoclinic structure with lattice parameters a 14.070(4), b 7.276(2), c 13.181(3) .ANG., b 107.74(6)°. All MSi2O2-dN2+2/3d:Eu2+ (M = Ca,

  2. Preparation and thermogravimetric study of some uranyl phosphates

    International Nuclear Information System (INIS)

    Schaekers, J.M.

    1970-10-01

    The preparation of uranyl ammonium phosphate trihydrate (UAP = UO 2 NH 4 PO 4 .3H 2 O), acid uranyl phosphate tetrahydrate(AUP = UO 2 HPO 4 .4H 2 O) and neutral uranyl phosphate tetrahydrate (NUPT = (UO 2 ) 3 (PO 4 ) 2 .4H 2 O) was investigated during the data from the literature. The thermal decomposition in different atmospheres, such as air, oxygen, nitrogen and argon, was studied in the temperature range 25-1000 0 C. It was found that the pyrophosphate U 2 O 3 P 2 O 7 is a stable decomposition product of UAP as well as of AUP. A mixture of U 3 O 8 and U 2 O 3 P 2 O 7 is obtained when the NUPT is decomposed in an oxygen-free atmosphere. NUPT however is stable in an oxidising atmosphere. Hydrogen and carbon reductions were also carried out, and UO 2 or (UO) 2 P 2 O 7 as well as mixtures of these two products can be obtained, depending on the starting material and the reduction temperature. The different reduction and decomposition reactions were studied by means of thermogravimetric analysis, and activation energies were calculated where possible. I.R. spectral analysis was also used to identify various products with the same composition [af

  3. Uranium abundance in some sudanese phosphate ores

    International Nuclear Information System (INIS)

    Adam, A.A.; Eltayeb, M.A.H.

    2009-01-01

    This work was carried out mainly to analysis of some Sudanese phosphate ores, for their uranium abundance and total phosphorus content measured as P 2 O 5 %. For this purpose, 30 samples of two types of phosphate ore from Eastern Nuba Mountains, in Sudan namely, Kurun and Uro areas were examined. In addition, the relationship between uranium and major, and trace elements were obtained, also, the natural radioactivity of the phosphate samples was measured, in order to characterize and differentiate between the two types of phosphate ores. The uranium abundance in Uro phosphate with 20.3% P 2 O 5 is five time higher than in Kurun phosphate with 26.7% P 2 O 5 . The average of uranium content was found to be 56.6 and 310 mg/kg for Kurun and Uro phosphate ore, respectively. The main elements in Kurun and Uro phosphate ore are silicon, aluminum, and phosphorus, while the most abundant trace elements in these two ores are titanium, strontium and barium. Pearson correlation coefficient revealed that uranium in Kurun phosphate shows strong positive correlation with P 2 O 5 , and its distribution is essentially controlled by the variations of P2O5 concentration, whereas uranium in Uro phosphate shows strong positive correlation with strontium, and its distribution is controlled by the variations of Sr concentration. Uranium behaves in different ways in Kurun phosphate and in Uro phosphate. Uro phosphate shows higher concentrations of all the estimated radionuclides than Kurun phosphate. According to the obtained results, it can be concluded that Uro phosphate is consider as secondary uranium source, and is more suitable for uranium recovery, because it has high uranium abundance and low P 2 O 5 %, than Kurun phosphate. (authors) [es

  4. High-pressure synthesis and characterizations of the R2Pt2O7 pyrochlores.

    Science.gov (United States)

    Cai, Yunqi; Cui, Qi; Cheng, Jinguang; Dun, Zhiling; Zhou, Haidong; Ma, Jie; Cruz, C. Dela; Yan, Jiaqiang; Li, Xiang; Zhou, Jianshi

    Pyrochlore R2B2O7 where R3 + stands for rear-earth ion and B4 + for a nonmagnetic cation such as Sn4 +or Ti4 +consist of an important family of geometrically frustrated magnets, which have been the focus of extensive investigations over last decades. To further enlarge the R2B2O7, we have chosen to stabilize the Pt-based cubic pyrochlores under HPHT conditions for two reasons: (1) Pt4 + is in a low-spin state which ionic radius is located in between Ti4 + (0.605\\x85) and Sn4 + (0.69\\x85), and (2) Pt4 + has a spatially much more extended 5d orbitals and thus enhanced Pt 5d-O 2p hybridizations that might modify the local anisotropic exchange interactions. Such an effect has never been taken into account in the previous studies. In this work, we will present the detailed characterizations on the pyrochlores R2Pt2O7 obtained under HPHT conditions. This work is supported by the National Science Foundation of China (Grant Nos.11304371, 11574377), part of the work was supported by the CEM, and NSF MRSEC, under Grant DMR-1420451, and Grant No. NSF-DMR-1350002.

  5. XAS study of V2O5/Al2O3 catalysts doped with rare earth oxides

    International Nuclear Information System (INIS)

    Centeno, M.A.; Malet, P.; Capitan, M.J.; Benitez, J.J.; Carrizosa, I.; Odriozola, J.A.

    1995-01-01

    This paper reports on XAS studies of well dispersed V 2 O 5 /Al 2 O 3 and V 2 O 5 /Sm 2 O 3 /Al 2 O 3 samples. XAS spectra at V-K and Sm-L III edges show that the rare earth oxide favours the formation of regular tetrahedral units, [VO 4 ], over the surface of the support. Positions of the preedge peak at the V-K edge, and intensities of the white line at the Sm-L III edge also suggest modifications in the electronic density around V and Sm atoms when they are simultaneously supported over Al 2 O 3 . ((orig.))

  6. HfO2 - rare earth oxide systems in the region with high content of rare earth oxide

    International Nuclear Information System (INIS)

    Shevchenko, A.V.; Lopato, L.M.

    1982-01-01

    Using the methods of annealing and hardenings (10 2 -10 4 deg/s cooling rate) and differential thermal analysis elements of state diagrams of HfO 2 - rare earth oxide (rare earths-La, Pr, Nd, Sm, Gd, Tb, Dy, Y, Er, Yb, Lu, Sc) systems from 1800 deg C up to melting in the range of 60-100 mol% rare earth oxide concentration were constructed. Regularities of HfQ 2 addition effect on high-temperature polymorphic transformations of rare earth oxides were studied. Results of investigation were discussed from viewpoint of crystal chemistry

  7. Magnetic properties and structural transitions of fluorite-related rare earth osmates Ln3OsO7 (Ln=Pr, Tb)

    International Nuclear Information System (INIS)

    Hinatsu, Yukio; Doi, Yoshihiro

    2013-01-01

    Ternary rare-earth osmates Ln 3 OsO 7 (Ln=Pr, Tb) have been prepared. They crystallize in an ortho-rhombic superstructure of cubic fluorite with space group Cmcm. Both of these compounds undergo a structural phase transition at 130 K (Ln=Pr) and 580 K (Ln=Tb). These compounds show complex magnetic behavior at low temperatures. Pr 3 OsO 7 exhibits magnetic transitions at 8 and 73 K, and Tb 3 OsO 7 magnetically orders at 8 and 60 K. The Os moments become one-dimensionally ordered, and when the temperature is furthermore decreased, it provokes the ordering in the Ln 3+ sublattice that simultaneously becomes three-dimensionally ordered with the Os sublattice. - Graphical abstract: Ternary rare-earth osmates Ln 3 OsO 7 (Ln=Pr, Tb) have been prepared. They crystallize in an orthorhombic superstructure of cubic fluorite with space group Cmcm. Both of these compounds undergo a structural phase transition at 130 K (Ln=Pr) and 580 K (Ln=Tb). These compounds show complex magnetic behavior at low temperatures. Pr 3 OsO 7 exhibits magnetic transitions at 8 and 73 K, and Tb 3 OsO 7 magnetically orders at 8 and 60 K. Highlights: ► Ternary rare-earth osmates Ln 3 OsO 7 (Ln=Pr, Tb) with an ordered defect-fluorite structure have been prepared. ► Both of these compounds undergo a structural phase transition at 130 K (Ln=Pr) and 580 K (Ln=Tb). ► These compounds show complex magnetic behavior at low temperatures due to magnetic ordering of Ln and Os.

  8. Enhanced Flux Pinning and Critical Current Density via Incorporation of Self-Assembled Rare-Earth Barium Tantalate Nanocolumns within YBa2Cu3O7 Films

    Energy Technology Data Exchange (ETDEWEB)

    Wee, Sung Hun [ORNL; Goyal, Amit [ORNL; Specht, Eliot D [ORNL; Cantoni, Claudia [ORNL; Zuev, Yuri L [ORNL; Selvamanickam, V. [SuperPower Incorporated, Schenectady, New York; Cook, Sylvester W [ORNL

    2010-01-01

    We report rare earth barium tantalates, Ba2RETaO6 (BRETO, RE = rare earth elements) as a new class of additives for superior flux-pinning in YBa2Cu3O7- (YBCO) films. BRETO compounds have excellent chemical inertness to and large lattice mismatch with YBCO. This results in phase separation and strain minimization driven self-assembly of BRETO nanocolumns within YBCO films. YBCO+4 vol% Ba2GdTaO6 films show similar Tc to that of an un-doped film of ~ 88.3 K, a higher self-field Jc of 3.8 MA/cm2 at 77 K, and significantly improved in-field Jc higher by a factor of 1.5-6 over entire magnetic field and angular ranges.

  9. Reaction between CO2 and phosphate to form carboxyphosphate?

    International Nuclear Information System (INIS)

    Knight, W.B.; Attwood, P.V.; Cleland, W.W.

    1986-01-01

    Carboxyphosphate (I) is thought to be an intermediate in the enzymic carboxylation of biotin by bicarbonate and MgATP, and a plausible mechanism of carboxyl transfer to the enolate of biotin involves decarboxylation to CO 2 and phosphate. Such a process would have to be reversible, however, as carboxylase reactions are reversible. To test this possibility, the authors undertook the synthesis of I under anhydrous conditions with a high mole fraction of CO 2 present. CO 2 was distilled into capillary tubes under vacuum containing dry tris-(tetrabutyl-ammonium)-phosphate in dimethylformamide. The tubes were sealed and warmed to -10 or 20 0 C and examined by 31 P NMR. Two resonances (1.7 ppm and -5.0 ppm) in addition to phosphate (3.3 ppm) were observed. The relative ratio of each peak to the phosphate one was dependent on the temperature and the concentrations of PO 4 3- and CO 2 . Upon freezing the tubes, cracking them, and release of the CO 2 , the two additional species decomposed slowly to PO 4 3- , and more rapidly to HPO 4 3- upon the addition of H 2 O. Under some conditions they observed an additional resonance (-7.0 ppm) which is most likely pyrophosphate (PP/sub i/). At high concentrations of PO 4 3- and CO 2 , PP/sub i/ was produced and precipitated from solution. The production of PP/sub i/ is most easily explained by attack of PO 4 3- on I. They are currently trying to identify the unknown species observed in the 31 P NMR spectra

  10. Preparation of Oleyl Phosphate-Modified TiO2/Poly(methyl methacrylate Hybrid Thin Films for Investigation of Their Optical Properties

    Directory of Open Access Journals (Sweden)

    Masato Fujita

    2015-01-01

    Full Text Available TiO2 nanoparticles (NPs modified with oleyl phosphate were synthesized through stable Ti–O–P bonds and were utilized to prepare poly(methyl methacrylate- (PMMA- based hybrid thin films via the ex situ route for investigation of their optical properties. After surface modification of TiO2 NPs with oleyl phosphate, IR and 13C CP/MAS NMR spectroscopy showed the presence of oleyl groups. The solid-state 31P MAS NMR spectrum of the product revealed that the signal due to oleyl phosphate (OP shifted upon reaction, indicating formation of covalent Ti–O–P bonds. The modified TiO2 NPs could be homogeneously dispersed in toluene, and the median size was 16.1 nm, which is likely to be sufficient to suppress Rayleigh scattering effectively. The TEM images of TiO2/PMMA hybrid thin films also showed a homogeneous dispersion of TiO2 NPs, and they exhibited excellent optical transparency even though the TiO2 content was 20 vol%. The refractive indices of the OP-modified TiO2/PMMA hybrid thin films changed higher with increases in TiO2 volume fraction, and the hybrid thin film with 20 vol% of TiO2 showed the highest refractive index (n = 1.86.

  11. Preparation method and thermal properties of samarium and europium-doped alumino-phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Sava, B.A., E-mail: savabogdanalexandru@yahoo.com [National Institute of Research and Development for Optoelectronics, Department for Optospintronics, 409 Atomistilor Street, P.O. Box MG – 5, RO-77125 Magurele (Romania); Elisa, M., E-mail: astatin18@yahoo.com [National Institute of Research and Development for Optoelectronics, Department for Optospintronics, 409 Atomistilor Street, P.O. Box MG – 5, RO-77125 Magurele (Romania); Boroica, L., E-mail: boroica_lucica@yahoo.com [National Institute for Lasers, Plasma and Radiation Physics, 77125 Magurele (Romania); Monteiro, R.C.C., E-mail: rcm@fct.unl.pt [Center of Materials Research/Institute for Nanostructures, Nanomodelling and Nanofabrication, (CENIMAT/I3N), Department of Materials Sciences, Faculty of Sciences and Technology, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

    2013-12-01

    Highlights: • Improved preparation method of rare-earth-doped phosphate glasses was done. • Working and annealing temperatures were lower than for undoped phosphate glass. • Doped glass viscosity is also lower and has quasi-linear variation with temperature. • Exothermic peak appears at about 555 °C and 685 °C, due to devitrification in glass. -- Abstract: The present work investigates alumino-phosphate glasses from Li{sub 2}O–BaO–Al{sub 2}O{sub 3}–La{sub 2}O{sub 3}–P{sub 2}O{sub 5} system containing Sm{sup 3+} and Eu{sup 3+} ions, prepared by two different ways: a wet raw materials mixing route followed by evaporation and melt-quenching, and by remelting of shards. The linear thermal expansion coefficient measured by dilatometry is identical for both rare-earth-doped phosphate glasses. Comparatively to undoped phosphate glass the linear thermal expansion coefficient increases with 2 × 10{sup −7} K{sup −1} when dopants are added. The characteristic temperatures very slowly decrease but can be considered constant with atomic weight, atomic number and f electrons number of the doping ions in the case of T{sub g} (vitreous transition temperature) and T{sub sr} (high annealing temperature) but slowly increase in the case of T{sub ir} (low annealing temperature–strain point) and very slowly increase, being practically constant in the case of T{sub D} (dilatometric softening temperature). Comparatively to undoped phosphate glass the characteristic temperatures of Sm and Eu-doped glasses present lower values. The higher values of electrical conductance for both doped glasses, comparatively to usual soda-lime-silicate glass, indicate a slightly reduced stability against water. The viscosity measurements, showed a quasi-linear variation with temperature the mean square deviation (R{sup 2}) being ranged between 0.872% and 0.996%. The viscosity of doped glasses comparatively to the undoped one is lower at the same temperature. Thermogravimetric

  12. Cs_7Sm_1_1[TeO_3]_1_2Cl_1_6 and Rb_7Nd_1_1[TeO_3]_1_2Br_1_6, the new tellurite halides of the tetragonal Rb_6LiNd_1_1[SeO_3]_1_2Cl_1_6 structure type

    International Nuclear Information System (INIS)

    Charkin, Dmitri O.; Black, Cameron; Downie, Lewis J.; Sklovsky, Dmitry E.; Berdonosov, Peter S.; Olenev, Andrei V.; Zhou, Wuzong; Lightfoot, Philip; Dolgikh, Valery A.

    2015-01-01

    Two new rare-earth – alkali – tellurium oxide halides were synthesized by a salt flux technique and characterized by single-crystal X-ray diffraction. The structures of the new compounds Cs_7Sm_1_1[TeO_3]_1_2Cl_1_6 (I) and Rb_7Nd_1_1[TeO_3]_1_2Br_1_6 (II) (both tetragonal, space group I4/mcm) correspond to the sequence of [MLn_1_1(TeO_3)_1_2] and [M_6X_1_6] layers and bear very strong similarities to those of known selenite analogs. We discuss the trends in similarities and differences in compositions and structural details between the Se and Te compounds; more members of the family are predicted. - Graphical abstract: Two new rare-earth – alkali – tellurium oxide halides were predicted and synthesized. - Highlights: • Two new rare-earth – alkali – tellurium oxide halides were synthesized. • They adopt slab structure of rare earth-tellurium-oxygen and CsCl-like slabs. • The Br-based CsCl-like slabs have been observed first in this layered family.

  13. Chlorination of UO2, PuO2, and rare-earth oxides using ZrCl4

    International Nuclear Information System (INIS)

    Sakamura, Yoshiharu; Inoue, Tadashi; Iwai, Takashi; Moriyama, Hirotake

    2001-01-01

    A new chlorination method using ZrCl 4 , which has a high reactivity with oxygen, has been investigated for more efficient oxide treatment. After actinide oxides are chlorinated and dissolved in a molten salt bath, actinide metals can be selectively collected using the electrorefining process. This process is well suited for pyrochemical reprocessing of metallic fuels. In LiCl-KCI eutectic melts, rare-earth oxides (Y 2 O 3 , La 2 O 3 , CeO 2 , and Nd 2 O 3 ) and actinide oxides (UO 2 and PuO 2 ) were chlorinated by adding ZrCl 4 . As a result, rare-earth and actinide elements were dissolved into the salt as trivalent ions and ZrO 2 was precipitated. When an excess of ZrCI 4 was added, oxides in powder form were completely chlorinated in five hours. It was demonstrated that the ZrCI 4 chlorination method, free from corrosive gas such as chlorine, was very simple and useful. (author)

  14. Enhanced NH{sub 3} gas sensing performance based on electrospun alkaline-earth metals composited SnO{sub 2} nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Shuang [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Key Laboratory of Physical Chemistry, School of Chemistry and Material Science, Heilongjiang University, Harbin 150080 (China); Kan, Kan [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Key Laboratory of Physical Chemistry, School of Chemistry and Material Science, Heilongjiang University, Harbin 150080 (China); Daqing Branch, Heilongjiang Academy of Sciences, Daqing 163319 (China); Yang, Ying; Jiang, Chao [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Key Laboratory of Physical Chemistry, School of Chemistry and Material Science, Heilongjiang University, Harbin 150080 (China); Gao, Jun [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Key Laboratory of Physical Chemistry, School of Chemistry and Material Science, Heilongjiang University, Harbin 150080 (China); Department of Chemistry, Harbin Normal University, Harbin 150025 (China); Jing, Liqiang [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Key Laboratory of Physical Chemistry, School of Chemistry and Material Science, Heilongjiang University, Harbin 150080 (China); Shen, Peikang [Department of Physics and Engineering Sun Yat-sen University, Guangzhou 510275 (China); Li, Li, E-mail: llwjjhlju@sina.cn [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, Key Laboratory of Physical Chemistry, School of Chemistry and Material Science, Heilongjiang University, Harbin 150080 (China); Key Laboratory of Chemical Engineering Process and Technology for High-efficiency Conversion, School of Chemistry and Material Science, Heilongjiang University, Harbin 150080 (China); and others

    2015-01-05

    Highlights: • The small-sized SnO{sub 2} (5–7 nm) were obtained by adding the alkaline-earth. • Sr-composited SnO{sub 2} nanofibers showed uniform nanotubes structure (Sr/SnO{sub 2}). • Sr/SnO{sub 2} showed an excellent sensing performance to NH{sub 3} at room temperature. - Abstract: One-dimensional alkaline-earth metals composited SnO{sub 2} (Ae/SnO{sub 2}) nanofibres were fabricated via electrospinning technique, followed by thermal treatment at 600 °C for 5 h. Transmission electron microscopy (TEM) studies showed that the nanoparticles size of Ae/SnO{sub 2} was 5–7 nm, which was smaller than the pristine SnO{sub 2} nanorods attached by 20 nm nanoparticles. Moreover, Sr/SnO{sub 2} nanocomposites showed uniform nanotubes structure with the wall thickness of about 30 nm, in which all the nanoparticles were connected to their neighbors by necks. The Sr/SnO{sub 2} nanotubes exhibited an excellent sensing response toward NH{sub 3} gas at room temperature, lower detection limit (10 ppm), faster response time (6 s towards 2000 ppm∼16 s towards 10 ppm) and better reversibility compared to the pristine SnO{sub 2} nanorods. The enhanced sensor performances were attributed to the higher conductivity of the Sr/SnO{sub 2}. Mott–Schottky plots (M–S) and electrochemical impedance spectroscopy (EIS) measurements indicated that the carrier density of Sr/SnO{sub 2} nanotubes was 3 fold of that pristine SnO{sub 2}.

  15. Electronic structures and Eu3+ photoluminescence behaviors in Y2Si2O7 and La2Si2O7

    International Nuclear Information System (INIS)

    Zhang Zhiya; Wang Yuhua; Zhang Feng; Cao Haining

    2011-01-01

    Research highlights: → Host excitation near the band gap of Y 2 Si 2 O 7 and La 2 Si 2 O 7 is analyzed. → The calculated result well explains Eu 3+ PL behaviors in Y 2 Si 2 O 7 and La 2 Si 2 O 7 . → The electronic structure and Eu 3+ VUV PL in La 2 Si 2 O 7 are first estimated. - Abstract: The electronic structures and linear optical properties of Y 2 Si 2 O 7 (YSO) and La 2 Si 2 O 7 (LSO) are calculated by LDA method based on the theory of DFT. Both YSO and LSO are direct-gap materials with the direct band gap of 5.89 and 6.06 eV, respectively. The calculated total and partial density of states indicate that in both YSO and LSO the valence band (VB) is mainly constructed from O 2p and the conduction band (CB) is mostly formed from Y 4d or La 5d. Both the calculated VB and CB of YSO exhibit relatively wider dispersion than that of LSO. In addition, the CB of YSO presents more electronic states. Meanwhile, the VB of LSO shows narrower energy distribution with higher electronic states density. The theoretical absorption of YSO shows larger bandwidth and higher intensity than that of LSO. The results are compared with the experimental host excitations and impurity photoluminescence in Eu 3+ -doped YSO and LSO.

  16. The beneficiation of mumbwa phosphate deposit by various ...

    African Journals Online (AJOL)

    The chemical composition of the ore averages 22.7 % P2O5 with the other constituents being 22.8% SiO2, 19.0% CaO, 7.0% Fe2O3, 4.0 % Al2O3 and 0.2% MgO. Beneficiation studies were performed to investigate methods of concentrating the phosphate values. Preliminary investigations involved detailed identification of ...

  17. Effect of rare-earth dopants on the growth and structural, optical, electrical and mechanical properties of L-arginine phosphate single crystals

    International Nuclear Information System (INIS)

    Arjunan, S.; Bhaskaran, A.; Kumar, R. Mohan; Mohan, R.; Jayavel, R.

    2010-01-01

    Research highlights: → Thorium, Lanthanum and Cerium rare-earth ions were doped with L-arginine phosphate material and the crystals were grown by slow evaporation technique. → The transparency of the rare-earth doped LAP crystals has enhanced compared to pure LAP. → The powder SHG measurements revealed that the SHG output of rare-earth doped LAP crystals increases considerably compared to that of LAP. → Vicker's hardness number of as-grown crystal of LAP is higher than that of rare-earth doped LAP crystals. - Abstract: Effect of Thorium, Lanthanum and Cerium rare-earth ions on the growth and properties of L-arginine phosphate single crystals has been reported. The incorporation of rare-earth dopants into the L-arginine phosphate crystals is confirmed by Inductively Coupled Plasma-Mass Spectroscopy analysis. The unit cell parameters for pure and rare-earth doped L-arginine phosphate crystals have been estimated by powder X-ray diffraction studies. UV-visible studies revealed the transmittance percentage and cut-off wavelengths of the grown crystals. Powder second harmonic generation measurement has been carried out for pure and doped L-arginine phosphate crystals. The dielectric behavior of the grown crystals was analyzed for different frequencies at room temperature. The mechanical properties have been determined for pure and the doped L-arginine phosphate crystals.

  18. Plasma treatment for influence of cold in different phases of formation of calcium phosphate on the surface of nanocomposite Al_2O_3/ZrO_2

    International Nuclear Information System (INIS)

    Santos, K.H.; Ferreira, J.A.; Osiro, D.; Nascimento, L.I.S.; Pallone, E.M.J.A.; Alves Junior, C.

    2016-01-01

    Among the different techniques used in surface treatment of biomaterials, the plasma has been noted for its ability to promote changes in surface roughness of the treated material. The objective of this study was to evaluate the influence of treatment by plasma in the formation of calcium phosphate nanocomposite on the surface of Al2O3/ZrO2 (5% by vol.). For this, samples were formed, calcined, sintered, surface treated and coated biomimeticamente plasma for 14 days. The surface characterization was performed by confocal microscopy and spectroscopy, Fourier transform infrared (FTIR). After coating, the samples were characterized by FTIR and X-ray diffraction X-ray (XRD). It was observed that the treatments improved surface roughness. Furthermore, regardless of the surface treatment were observed only three phases of calcium phosphates: HA α -TCP and -β-TCP. It is worth noting that depending on the composition, there are variations in the amount of phosphates, as well as the percentages of the different phases. (author)

  19. A sodium gadolinium phosphate with two different types of tunnel structure: Synthesis, crystal structure, and optical properties of Na3GdP2O8

    International Nuclear Information System (INIS)

    Fang, M.; Cheng, W.-D.; Zhang, H.; Zhao, D.; Zhang, W.-L.; Yang, S.-L.

    2008-01-01

    A sodium gadolinium phosphate crystal, Na 3 GdP 2 O 8 , has been synthesized by a high-temperature solution reaction, and it exhibits a new structural family of the alkali-metal-rare-earth phosphate system. Although many compounds with formula M 3 LnP 2 O 8 have been reported, but they were shown to be orthorhombic [R. Salmon, C. Parent, M. Vlasse, G. LeFlem, Mater. Res. Bull. 13 (1978) 439] rather than monoclinic as shown in this paper. Single-crystal X-ray diffraction analysis shows the structure to be monoclinic with space group C2/c and the cell parameters: a=27.55 (25), b=5.312 (4), c=13.935(11) A, β=91.30(1) o , and V=2038.80 A 3 , Z=4. Its structure features a three-dimensional GdP 2 O 8 3- anionic framework with two different types of interesting tunnels at where Na atoms are located by different manners. The framework is constructed by Gd polyhedra and isolated PO 4 tetrahedra. It is different from the structure of K 3 NdP 2 O 8 [R. Salmon, C. Parent, M. Vlasse, G. LeFlem, Mater. Res. Bull. 13 (1978) 439] with space group P2 1 /m that shows only one type of tunnel. The emission spectrum and the absorption spectrum of the compound have been investigated. Additionally, the calculations of band structure, density of states, dielectric constants, and refractive indexes have been also performed with the density functional theory method. The obtained results tend to support the experimental data. - Graphical abstract: Projection of the structure of Na 3 GdP 2 O 8 with a unit cell edge along the b-axis. The Na-O bonds are omitted for clarity

  20. Peroxy defects in Rocks and H2O2 formation on the early Earth

    Science.gov (United States)

    Gray, A.; Balk, M.; Mason, P.; Freund, F.; Rothschild, L.

    2013-12-01

    An oxygen-rich atmosphere appears to have been a prerequisite for complex life to evolve on Earth and possibly elsewhere in the Universe. The question is still shrouded in uncertainty how free oxygen became available on the early Earth. Here we study processes of peroxy defects in silicate minerals which, upon weathering, generate mobilized electronic charge carriers resulting in oxygen formation in an initially anoxic subsurface environment. Reactive Oxygen Species (ROS) are precursors to molecular oxygen during this process. Due to their toxicity they may have strongly influenced the evolution of life. ROS are generated during hydrolysis of peroxy defects, which consist of pairs of oxygen anions. A second pathway for formation occurs during (bio) transformations of iron sulphide minerals. ROS are produced and consumed by intracellular and extracellular reactions of Fe, Mn, C, N, and S species. We propose that despite an overall reducing or neutral oxidation state of the macroenvironment and the absence of free O2 in the atmosphere, microorganisms on the early Earth had to cope with ROS in their microenvironments. They were thus under evolutionary pressure to develop enzymatic and other defenses against the potentially dangerous, even lethal effects of ROS and oxygen. We have investigated how oxygen might be released through weathering and test microorganisms in contact with rock surfaces. Our results show how early Life might have adapted to oxygen. Early microorganisms must have "trained" to detoxify ROS prior to the evolution of aerobic metabolism and oxygenic photosynthesis. A possible way out of this dilemma comes from a study of igneous and high-grade metamorphic rocks, whose minerals contain a small but significant fraction of oxygen anions in the valence state 1- , forming peroxy links of the type O3Si-OO-SiO3 [1, 2]. As water hydrolyzes the peroxy links hydrogen peroxide, H2O2, forms. Continued experimental discovery of H2O2 formation at rock

  1. Np(V)O2+ sorption on hydroxyapatite-effect of calcium and phosphate anions

    International Nuclear Information System (INIS)

    Thakur, P.; Choppin, G.R.; Moore, R.C.

    2006-01-01

    The sorption of NpO 2 + from aqueous solution on hydroxyapatite was studied as a function of the amount of sorbent, initial NpO 2 + concentration, ionic strength and pcH. The hydroxyapatite was characterized by SEM, EDS, XRD, FT-IR and ICP-MS measurements. At ionic strengths of 0.10 to 5.00 M NaClO 4 , the sorption increased with increased pcH to a maximum between pcH 8-8.5, then decreased as the pcH increased. The kinetics of NpO 2 + sorption on hydroxyapatite followed Lagergren first order kinetics. The temperature dependence of sorption was small in the range of 273-283 K, but increased more sharply at higher temperatures of 298-333 K. The heat of sorption of NpO 2 + was endothermic and the free energy values were exothermic indicating large, positive entropy. The activation energy for the sorption process was calculated to be 29.52 ± 1.2 kJ/mole. The effect of calcium and phosphate on NpO 2 + sorption was studied as a function of concentration and pcH. (orig.)

  2. Magnesium Potassium Phosphate Compound for Immobilization of Radioactive Waste Containing Actinide and Rare Earth Elements

    Directory of Open Access Journals (Sweden)

    Sergey E. Vinokurov

    2018-06-01

    Full Text Available The problem of effective immobilization of liquid radioactive waste (LRW is key to the successful development of nuclear energy. The possibility of using the magnesium potassium phosphate (MKP compound for LRW immobilization on the example of nitric acid solutions containing actinides and rare earth elements (REE, including high level waste (HLW surrogate solution, is considered in the research work. Under the study of phase composition and structure of the MKP compounds that is obtained by the XRD and SEM methods, it was established that the compounds are composed of crystalline phases—analogues of natural phosphate minerals (struvite, metaankoleite. The hydrolytic stability of the compounds was determined according to the semi-dynamic test GOST R 52126-2003. Low leaching rates of radionuclides from the compound are established, including a differential leaching rate of 239Pu and 241Am—3.5 × 10−7 and 5.3 × 10−7 g/(cm2∙day. As a result of the research work, it was concluded that the MKP compound is promising for LRW immobilization and can become an alternative material combining the advantages of easy implementation of the technology, like cementation and the high physical and chemical stability corresponding to a glass-like compound.

  3. Novel ZnO/MgO/Fe2O3 composite optomagnetic nanoparticles

    International Nuclear Information System (INIS)

    Kamińska, I; Sikora, B; Fronc, K; Dziawa, P; Sobczak, K; Minikayev, R; Paszkowicz, W; Elbaum, D

    2013-01-01

    A facile sol–gel synthesis of novel ZnO/MgO/Fe 2 O 3 nanoparticles (NPs) is reported and their performance is compared to that of ZnO/MgO. Powder x-ray diffraction (XRD) patterns reveal the crystal structure of the prepared samples. The average particle size of the sample was found to be 4.8 nm. The optical properties were determined by UV–vis absorption and fluorescence measurements. The NPs are stable in biologically relevant solutions (phosphate buffered saline (PBS), 20 mM, pH = 7.0) contrary to ZnO/MgO NPs which degrade in the presence of inorganic phosphate. Superparamagnetic properties were determined with a superconducting quantum interference device (SQUID). Biocompatible and stable in PBS ZnO/MgO/Fe 2 O 3 core/shell composite nanocrystals show luminescent and magnetic properties confined to a single NP at room temperature (19–24 ° C), which may render the material to be potentially useful for biomedical applications. (paper)

  4. Synthesis and optical properties of polycrystalline Li{sub 2}Al{sub 2}B{sub 2}O{sub 7} (LABO)

    Energy Technology Data Exchange (ETDEWEB)

    Dagdale, S. R., E-mail: shiva.dagdale68@gmail.com; Muley, G. G., E-mail: gajananggm@yahoo.co.in [Department of Physics Sant Gadge Baba Amravati University, Amravati, Maharashtra, India-444602 (India)

    2016-05-06

    A polycrystalline lithium aluminum borate (Li{sub 2}Al{sub 2}B{sub 2}O{sub 7}, LABO) has been synthesized by using simple solid-state technique. The obtained LABO polycrystalline was characterized by powder X-ray diffraction; Fourier transform infrared (FT-IR) spectroscopy and second harmonic generation (SHG) efficiency measurement. The functional groups were identified using the FT-IR spectroscopic data. The SHG efficiency of the polycrystalline material was obtained by the classic Kurtz powder technique using a fundamental wavelength 1064 nm of Nd:YAG laser and it is found to be 1.4 times that of potassium dihydrogen phosphate (KDP).

  5. Structure and properties of gadolinium loaded calcium phosphate glasses

    International Nuclear Information System (INIS)

    Wang, Cuiling; Liang, Xiaofeng; Li, Haijian; Yu, Huijun; Li, Zhen; Yang, Shiyuan

    2014-01-01

    The glass samples with composition xGd 2 O 3 –(50 − x)CaO–50P 2 O 5 (0 ⩽ x ⩽ 9 mol%) were prepared by the conventional melt quench method. The structure and properties of gadolinium loaded in calcium phosphate glasses were investigated using XRD, SEM, DTA, IR and Raman spectroscopy. The XRD and SEM analysis for the samples show that the majority of samples are amorphous, and crystallization occurs when the content of Gd 2 O 3 containing is up to 6 mol%. Two main crystalline phases, Ca 2 P 2 O 7 and Gd 3 (P 2 O 7 ) 3 , are embedded in an amorphous matrix. IR and Raman data indicate that glass structure consists of predominantly metaphosphate (Q 2 ) units and the depolymerization of phosphate network with the addition of Gd 2 O 3 . Both the chemical durability and the glass transition temperature (T g ) are improved with the increase of Gd 2 O 3 , which suggests that the Gd acts a role of strengthening the cross-links between the phosphate chains of the glass

  6. The electrorheological properties of nano-sized SiO2 particle materials doped with rare earths

    International Nuclear Information System (INIS)

    Liu Yang; Liao Fuhui; Li Junran; Zhang Shaohua; Chen Shumei; Wei Chenguan; Gao Song

    2006-01-01

    Electrorheological (ER) materials of pure SiO 2 and SiO 2 doped with rare earths (RE = Ce, Gd, Y) (non-metallic glasses (silicates)) were prepared using Na 2 SiO 3 and RECl 3 as starting materials. The electrorheological properties are not enhanced by all rare earth additions. The material doped with Ce exhibits the best ER performance

  7. Effect of rare-earth dopants on the growth and structural, optical, electrical and mechanical properties of L-arginine phosphate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Arjunan, S., E-mail: arjunan_hce@yahoo.co.i [Department of Physics, Sri Ramachandra University, Porur, Chennai (India); Bhaskaran, A. [Department of Physics, Dr. Ambedkar Government College, Chennai (India); Kumar, R. Mohan; Mohan, R. [Department of Physics, Presidency College, Chennai (India); Jayavel, R. [Crystal Growth Centre, Anna University, Chennai (India)

    2010-09-17

    Research highlights: {yields} Thorium, Lanthanum and Cerium rare-earth ions were doped with L-arginine phosphate material and the crystals were grown by slow evaporation technique. {yields} The transparency of the rare-earth doped LAP crystals has enhanced compared to pure LAP. {yields} The powder SHG measurements revealed that the SHG output of rare-earth doped LAP crystals increases considerably compared to that of LAP. {yields} Vicker's hardness number of as-grown crystal of LAP is higher than that of rare-earth doped LAP crystals. - Abstract: Effect of Thorium, Lanthanum and Cerium rare-earth ions on the growth and properties of L-arginine phosphate single crystals has been reported. The incorporation of rare-earth dopants into the L-arginine phosphate crystals is confirmed by Inductively Coupled Plasma-Mass Spectroscopy analysis. The unit cell parameters for pure and rare-earth doped L-arginine phosphate crystals have been estimated by powder X-ray diffraction studies. UV-visible studies revealed the transmittance percentage and cut-off wavelengths of the grown crystals. Powder second harmonic generation measurement has been carried out for pure and doped L-arginine phosphate crystals. The dielectric behavior of the grown crystals was analyzed for different frequencies at room temperature. The mechanical properties have been determined for pure and the doped L-arginine phosphate crystals.

  8. [H3N(CH2)4NH3]2[Al4(C2O4)(H2PO4)2(PO4)4].4[H2O]: A new layered aluminum phosphate-oxalate

    International Nuclear Information System (INIS)

    Peng Li; Li Jiyang; Yu Jihong; Li Guanghua; Fang Qianrong; Xu Ruren

    2005-01-01

    A new layered inorganic-organic hybrid aluminum phosphate-oxalate [H 3 N(CH 2 ) 4 NH 3 ] 2 [Al 4 (C 2 O 4 )(H 2 PO 4 ) 2 (PO 4 ) 4 ].4[H 2 O](AlPO-CJ25) has been synthesized hydrothermally, by using 1,4-diaminobutane (DAB) as structure-directing agent. The structure has been solved by single-crystal X-ray diffraction analysis and further characterized by IR, 31 P MAS NMR, TG-DTA as well as compositional analyses. Crystal data: the triclinic space group P-1, a=8.0484(7) A, b=8.8608(8) A, c=13.2224(11) A, α=80.830(6) deg. , β=74.965(5) deg. , γ=78.782(6) deg. , Z=2, R 1[ I >2 σ ( I )] =0.0511 and wR 2(alldata) =0.1423. The alternation of AlO 4 tetrahedra and PO 4 tetrahedra gives rise to the four-membered corner-sharing chains, which are interconnected through AlO 6 octahedra to form the layered structure with 4,6-net sheet. Interestingly, oxalate ions are bis-bidentately bonded by participating in the coordination of AlO 6 , and bridging the adjacent AlO 6 octahedra. The layers are held with each other through strong H-bondings between the terminal oxygens. The organic ammonium cations and water molecules are located in the large cavities between the interlayer regions. -- Graphical abstract: The alternation of AlO 4 tetrahedra and PO 4 tetrahedra gives rise to the four-membered corner-sharing chains, which are interconnected through AlO 6 octahedra to form the layered structure with 4,6-net sheet. Oxalate ions are bis-bidentately boned by participating in the coordination of AlO 6 , and bridging the adjacent AlO 6 octahedra

  9. Novel bluish white-emitting CdBaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor for near-UV white-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Derbel, Mouna [Laboratory of Industrial Chemistry, National School of Engineers of Sfax, University of Sfax, BPW 3038 Sfax (Tunisia); Mbarek, Aïcha, E-mail: mbarekaicha@yahoo.fr [Laboratory of Industrial Chemistry, National School of Engineers of Sfax, University of Sfax, BPW 3038 Sfax (Tunisia); Chadeyron, Geneviève [Clermont Université, ENSCCF, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); Fourati, Mohieddine [Laboratory of Industrial Chemistry, National School of Engineers of Sfax, University of Sfax, BPW 3038 Sfax (Tunisia); Zambon, Daniel [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); Mahiou, Rachid [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, ICCF, BP 80026, F-63171 Aubiere (France)

    2016-08-15

    A new bluish white-emitting phosphor based on a phosphate host matrix, CdBaP{sub 2}O{sub 7}:Eu{sup 2+}, was prepared by a conventional solid-state reaction method. The photoluminescence properties were investigated in both ultraviolet (UV) and vacuum ultraviolet (VUV) regions. The band-gaps of Eu-doped CdBaP{sub 2}O{sub 7} powders can be tuned in the ranges of 2.26–2 eV. The Eu{sup 2+}-doped CdBaP{sub 2}O{sub 7} phosphor was efficiently excited at wavelengths of 250–400 nm, which is suitable for the blue emission band for near-UV light-emitting-diode (LED) chips (360–400 nm) and red emission peaks up to 700 nm. CdBaP{sub 2}O{sub 7}:Eu{sup 2+} displays two different luminescence centers, which were suggested to Ba{sup 2+} and Cd{sup 2+} sites in the host. The dependence of luminescence intensity on temperatures was measured. The chromaticity coordinates and activation energy for thermal quenching were reported. The phosphor shows a good thermal stability on temperature quenching.

  10. Analysis and prediction of stacking sequences in intercalated lamellar vanadium phosphates

    Energy Technology Data Exchange (ETDEWEB)

    Gautier, Romain [Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS - Ecole Nationale Superieure de Chimie de Rennes (France); Centre Nationale de la Recherche Scientifique (CNRS), Institut des Materiaux Jean Rouxel (IMN), Universite de Nantes (France); Fourre, Yoann; Furet, Eric; Gautier, Regis; Le Fur, Eric [Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS - Ecole Nationale Superieure de Chimie de Rennes (France)

    2015-04-15

    An approach is presented that enables the analysis and prediction of stacking sequences in intercalated lamellar vanadium phosphates. A comparison of previously reported vanadium phosphates reveals two modes of intercalation: (i) 3d transition metal ions intercalated between VOPO{sub 4} layers and (ii) alkali/alkaline earth metal ions between VOPO{sub 4}.H{sub 2}O layers. Both intercalations were investigated using DFT calculations in order to understand the relative shifts of the vanadium phosphate layers. These calculations in addition to an analysis of the stacking sequences in previously reported materials enable the prediction of the crystal structures of M{sub x}(VOPO{sub 4}).yH{sub 2}O (M = Cs{sup +}, Cd{sup 2+} and Sn{sup 2+}). Experimental realization and structural determination of Cd(VOPO{sub 4}){sub 2}.4H{sub 2}O by single-crystal X-ray diffraction confirmed the predicted stacking sequences. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Solubility of rare earth-iron borates in the Bi2O3-B2O3 melt and their crystallization

    International Nuclear Information System (INIS)

    Al'shinskaya, L.I.; Leonyuk, N.I.; Nadezhnaya, T.B.; Timchenko, T.I.

    1979-01-01

    The temperature dependence of solubility of RFe 3 (BO 3 ) 4 (R=Y, Gd, Nd, Er) double borates in the Bi 2 O 3 -B 2 O 3 solution-melt is studied. The solubility curves in the range from 25 to 52 mol% are plotted. The character of curves is almost similar. At equal temperatures YFe 3 (BO 3 ) 4 and ErFe 3 (BO 3 ) 4 have the highest solubility and GaFe 3 (BO 3 ) 4 - the lowest one. It is shown that in the Bi 2 O 3 -B 2 O 3 base solution-melt the wide temperature range of monophase crystallization of rare earth - iron borates exists and the stratification is not observed. Thus, for the first time obtained are the crystals of rare earth-iron borates suitable for the investigation of their physical properties

  12. Preparation of calcium phosphate paste

    International Nuclear Information System (INIS)

    Mohd Reusmaazran Yusof; Norzita Yaacob; Idris Besar; Che Seman Mahmood; Rusnah Mustafa

    2010-01-01

    Calcium phosphate paste were prepared by mixing between calcium sodium potassium phosphate, Ca 2 NaK (PO 4 ) 2 (CSPP) and monocalcium phosphate monohydrate, Ca(H 2 PO 4 ) 2 .H 2 O (MCPM). CSPP were obtained by reaction between calcium hydrogen phosphate (CaHPO 4 ), potassium carbonate (K 2 CO 3 ) and sodium carbonate (Na 2 CO 3 ) in solid state sintering process followed by quenching in air at 1000 degree Celsius. The paste was aging in simulated body fluid (SBF) for 0.5, 1, 3, 6, 12, 24, 48 hrs, 3, 7 and 14 days. The morphological investigation indicated the formation of apatite crystal were first growth after 24 hours. The obvious growth of apatite crystal was shown at 3 days. The obvious growth of apatite crystal was shown in 7 and 14 days indicated the prediction of paste would have rapid reaction with bone after implantation. (author)

  13. Enhancement of CO Evolution by Modification of Ga2O3 with Rare-Earth Elements for the Photocatalytic Conversion of CO2 by H2O.

    Science.gov (United States)

    Tatsumi, Hiroyuki; Teramura, Kentaro; Huang, Zeai; Wang, Zheng; Asakura, Hiroyuki; Hosokawa, Saburo; Tanaka, Tsunehiro

    2017-12-12

    Modification of the surface of Ga 2 O 3 with rare-earth elements enhanced the evolution of CO as a reduction product in the photocatalytic conversion of CO 2 using H 2 O as an electron donor under UV irradiation in aqueous NaHCO 3 as a pH buffer, with the rare-earth species functioning as a CO 2 capture and storage material. Isotope experiments using 13 CO 2 as a substrate clearly revealed that CO was generated from the introduced gaseous CO 2 . In the presence of the NaHCO 3 additive, the rare-earth (RE) species on the Ga 2 O 3 surface are transformed into carbonate hydrates (RE 2 (CO 3 ) 3 ·nH 2 O) and/or hydroxycarbonates (RE 2 (OH) 2(3-x) (CO 3 ) x ) which are decomposed upon photoirradiation. Consequently, Ag-loaded Yb-modified Ga 2 O 3 exhibits much higher activity (209 μmol h -1 of CO) than the pristine Ag-loaded Ga 2 O 3 . The further modification of the surface of the Yb-modified Ga 2 O 3 with Zn afforded a selectivity toward CO evolution of 80%. Thus, we successfully achieved an efficient Ag-loaded Yb- and Zn-modified Ga 2 O 3 photocatalyst with high activity and controllable selectivity, suitable for use in artificial photosynthesis.

  14. Application of Cu{sub 2}O-doped phosphate glasses for bandpass filter

    Energy Technology Data Exchange (ETDEWEB)

    Elhaes, H. [Physics Department, Faculty of Women for Arts, Science and Education, Ain Shams University, 11757 Cairo (Egypt); Attallah, M., E-mail: m_atallah94@yahoo.com [Basic Science Department, Higher Technological Institute, 10th of Ramadan City (Egypt); Elbashar, Y.; El-Okr, M. [Physics Department, Faculty of Science, Al Azhar University, Cairo (Egypt); Ibrahim, M. [Spectroscopy Department, National Research Centre, 12311 Dokki, Cairo (Egypt)

    2014-09-15

    Phosphate glasses doped with copper ions having general composition 42P{sub 2}O{sub 5}–39ZnO–(18−x) Na{sub 2}O–1CaO–xCu{sub 2}O [x=2, 4, 6, 8, 10 mol%] were prepared using a conventional melt-quench technique. Physical and chemical properties of the glasses were investigated using X-ray diffraction technique and UV–visible optical absorption. The density was measured by Archimedes' method, and molar volume (V{sub M}) was calculated. It is found that density and molar volume show opposite trend by increasing Cu{sub 2}O content. Absorbance and transmittance at the normal incidence are measured by a spectrophotometer in the spectral range of 190–1100 nm. Analyses of the obtained results were considered in the frame of current theories. Absorption data were used for absorption coefficient, the optical band gap (E{sub opt}), the cutoff in UV and IR bands to the bandpass filter, which confirmed the optical properties of this type of filter. E{sub opt} values for different glass samples are found to decrease with increasing Cu{sub 2}O content.

  15. Hydrogen permeation resistant phosphate coatings

    International Nuclear Information System (INIS)

    McGuire, J.C.

    1979-01-01

    A method for reducing hydrogen diffusion through metal wherein the metal is coated with a phosphate-radical-containing, phosphate-glass-forming material on at least one surface thereof. The coating is then heated to at least 350 0 C to form a phosphate glass. This method is especially applicable to nuclear reactors to minimize tritium diffusion. The coating is preferably formed with a solution of phosphoric acid which may also contain compounds such as MnSO 4 , SiO 2 and Na 2 Cr 2 0 7 . (author)

  16. Response of Gd 2 Ti 2 O 7 and La 2 Ti 2 O 7 to swift-heavy ion irradiation and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sulgiye; Lang, Maik; Tracy, Cameron L.; Zhang, Jiaming; Zhang, Fuxiang; Trautmann, Christina; Rodriguez, Matias D.; Kluth, Patrick; Ewing, Rodney C.

    2015-07-01

    Swift heavy ion (2 GeV 181Ta) irradiation-induced amorphization and temperature-induced recrystallization of cubic pyrochlore Gd2Ti2O7 (Fd3¯m) are compared with the response of a compositionally-similar material with a monoclinic-layered perovskite-type structure, La2Ti2O7 (P21). The averaged electronic energy loss, dE/dx, was 37 keV/nm and 35 keV/nm in Gd2Ti2O7 and La2Ti2O7, respectively. Systematic analysis of the structural modifications was completed using transmission electron microscopy, synchrotron X-ray diffraction, Raman spectroscopy, and small-angle X-ray scattering. Increasing ion-induced amorphization with increasing ion fluence was evident in the X-ray diffraction patterns of both compositions by a reduction in the intensity of the diffraction maxima concurrent with the growth in intensity of a broad diffuse scattering halo. Transmission electron microscopy analysis showed complete amorphization within ion tracks (diameter: ~10 nm) for the perovskite-type material; whereas a concentric, core–shell morphology was evident in the ion tracks of the pyrochlore, with an outer shell of disordered yet still crystalline material with the fluorite structure surrounding an amorphous track core (diameter: ~9 nm). The radiation response of both titanate oxides with the same stoichiometry can be understood in terms of differences in their structures and compositions. While the radiation damage susceptibility of pyrochlore A2B2O7 materials decreases as a function of the cation radius ratio rA/rB, the current study correlates this behavior with the stability field of monoclinic structures, where rLa/rTi > rGd/rTi. Isochronal annealing experiments of the irradiated materials showed complete recrystallization of La2Ti2O7 at 775 °C and of Gd2Ti2O7 at 850 °C. The annealing behavior is discussed in terms of enhanced damage recovery in La2Ti2O7, compared to the pyrochlore compounds Gd2Ti2O7. The difference in the recrystallization behavior may be related to structural

  17. Exposure to tri-o-cresyl phosphate detected in jet airplane passengers

    International Nuclear Information System (INIS)

    Liyasova, Mariya; Li, Bin; Schopfer, Lawrence M.; Nachon, Florian; Masson, Patrick; Furlong, Clement E.; Lockridge, Oksana

    2011-01-01

    The aircraft cabin and flight deck ventilation are supplied from partially compressed unfiltered bleed air directly from the engine. Worn or defective engine seals can result in the release of engine oil into the cabin air supply. Aircrew and passengers have complained of illness following such “fume events”. Adverse health effects are hypothesized to result from exposure to tricresyl phosphate mixed esters, a chemical added to jet engine oil and hydraulic fluid for its anti-wear properties. Our goal was to develop a laboratory test for exposure to tricresyl phosphate. The assay was based on the fact that the active-site serine of butyrylcholinesterase reacts with the active metabolite of tri-o-cresyl phosphate, cresyl saligenin phosphate, to make a stable phosphorylated adduct with an added mass of 80 Da. No other organophosphorus agent makes this adduct in vivo on butyrylcholinesterase. Blood samples from jet airplane passengers were obtained 24–48 h after completing a flight. Butyrylcholinesterase was partially purified from 25 ml serum or plasma, digested with pepsin, enriched for phosphorylated peptides by binding to titanium oxide, and analyzed by mass spectrometry. Of 12 jet airplane passengers tested, 6 were positive for exposure to tri-o-cresyl phosphate that is, they had detectable amounts of the phosphorylated peptide FGEpSAGAAS. The level of exposure was very low. No more than 0.05 to 3% of plasma butyrylcholinesterase was modified. None of the subjects had toxic symptoms. Four of the positive subjects were retested 3 to 7 months following their last airplane trip and were found to be negative for phosphorylated butyrylcholinesterase. In conclusion, this is the first report of an assay that detects exposure to tri-o-cresyl phosphate in jet airplane travelers. -- Highlights: ► Travel on jet airplanes is associated with an illness, aerotoxic syndrome. ► A possible cause is exposure to tricresyl phosphate in engine lubricating oil. ► A blood

  18. Exposure to tri-o-cresyl phosphate detected in jet airplane passengers

    Energy Technology Data Exchange (ETDEWEB)

    Liyasova, Mariya, E-mail: mliyasov@unmc.edu [Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198-5950 (United States); Department of Environmental, Agricultural, and Occupational Health, University of Nebraska Medical Center, Omaha, NE (United States); Li, Bin, E-mail: binli@unmc.edu [Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198-5950 (United States); Schopfer, Lawrence M., E-mail: lmschopf@unmc.edu [Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198-5950 (United States); Nachon, Florian, E-mail: fnachon@nachon.net [Departement de Toxicologie, Institut de Recherche Biomedicale des Armees, 24 avenue des Marquis du Gresivaudan, 38702 La Tronche (France); Masson, Patrick, E-mail: pmasson@unmc.edu [Departement de Toxicologie, Institut de Recherche Biomedicale des Armees, 24 avenue des Marquis du Gresivaudan, 38702 La Tronche (France); Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198-5950 (United States); Furlong, Clement E., E-mail: clem@uw.edu [Department of Medicine (Div. Medical Genetics) and Genome Sciences, University of Washington, Seattle, WA 98195 (United States); Lockridge, Oksana, E-mail: olockrid@unmc.edu [Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198-5950 (United States); Department of Environmental, Agricultural, and Occupational Health, University of Nebraska Medical Center, Omaha, NE (United States)

    2011-11-15

    The aircraft cabin and flight deck ventilation are supplied from partially compressed unfiltered bleed air directly from the engine. Worn or defective engine seals can result in the release of engine oil into the cabin air supply. Aircrew and passengers have complained of illness following such 'fume events'. Adverse health effects are hypothesized to result from exposure to tricresyl phosphate mixed esters, a chemical added to jet engine oil and hydraulic fluid for its anti-wear properties. Our goal was to develop a laboratory test for exposure to tricresyl phosphate. The assay was based on the fact that the active-site serine of butyrylcholinesterase reacts with the active metabolite of tri-o-cresyl phosphate, cresyl saligenin phosphate, to make a stable phosphorylated adduct with an added mass of 80 Da. No other organophosphorus agent makes this adduct in vivo on butyrylcholinesterase. Blood samples from jet airplane passengers were obtained 24-48 h after completing a flight. Butyrylcholinesterase was partially purified from 25 ml serum or plasma, digested with pepsin, enriched for phosphorylated peptides by binding to titanium oxide, and analyzed by mass spectrometry. Of 12 jet airplane passengers tested, 6 were positive for exposure to tri-o-cresyl phosphate that is, they had detectable amounts of the phosphorylated peptide FGEpSAGAAS. The level of exposure was very low. No more than 0.05 to 3% of plasma butyrylcholinesterase was modified. None of the subjects had toxic symptoms. Four of the positive subjects were retested 3 to 7 months following their last airplane trip and were found to be negative for phosphorylated butyrylcholinesterase. In conclusion, this is the first report of an assay that detects exposure to tri-o-cresyl phosphate in jet airplane travelers. -- Highlights: Black-Right-Pointing-Pointer Travel on jet airplanes is associated with an illness, aerotoxic syndrome. Black-Right-Pointing-Pointer A possible cause is exposure to

  19. Electrochemical Behavior of Molten V2O5-K2S2O7-KHSO4 Systems

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bjerrum, Niels; Berg, Rolf W.

    1997-01-01

    The electrochemical behavior of K2S2O7-KHSO4-V2O5, K2S2O7-V2O4 and K2S2O7-KHSO4-V2O4 melts was studied in argon and SO2/air atmospheres using a gold electrode. In order to identify the voltammetric waves due to KHSO4, molten KHSO4 and mixtures of K2S2O7-KHSO4 were investigated by voltammetry...

  20. 2-O-α-D-glucosylglycerol phosphorylase from Bacillus selenitireducens MLS10 possessing hydrolytic activity on β-D-glucose 1-phosphate.

    Directory of Open Access Journals (Sweden)

    Takanori Nihira

    Full Text Available The glycoside hydrolase family (GH 65 is a family of inverting phosphorylases that act on α-glucosides. A GH65 protein (Bsel_2816 from Bacillus selenitireducens MLS10 exhibited inorganic phosphate (Pi-dependent hydrolysis of kojibiose at the rate of 0.43 s(-1. No carbohydrate acted as acceptor for the reverse phosphorolysis using β-D-glucose 1-phosphate (βGlc1P as donor. During the search for a suitable acceptor, we found that Bsel_2816 possessed hydrolytic activity on βGlc1P with a k cat of 2.8 s(-1; moreover, such significant hydrolytic activity on sugar 1-phosphate had not been reported for any inverting phosphorylase. The H2 (18O incorporation experiment and the anomeric analysis during the hydrolysis of βGlc1P revealed that the hydrolysis was due to the glucosyl-transferring reaction to a water molecule and not a phosphatase-type reaction. Glycerol was found to be the best acceptor to generate 2-O-α-D-glucosylglycerol (GG at the rate of 180 s(-1. Bsel_2816 phosphorolyzed GG through sequential Bi-Bi mechanism with a k cat of 95 s(-1. We propose 2-O-α-D-glucopyranosylglycerol: phosphate β-D-glucosyltransferase as the systematic name and 2-O-α-D-glucosylglycerol phosphorylase as the short name for Bsel_2816. This is the first report describing a phosphorylase that utilizes polyols, and not carbohydrates, as suitable acceptor substrates.

  1. Titanium-bearing phases in the Earth's mantle (evidence from experiments in the MgO-SiO2-TiO2 ±Al2O3 system at 10-24 GPa)

    Science.gov (United States)

    Sirotkina, Ekaterina; Bobrov, Andrey; Bindi, Luca; Irifune, Tetsuo

    2017-04-01

    Introduction Despite significant interest of experimentalists to the study of geophysically important phase equilibria in the Earth's mantle and a huge experimental database on a number of the model and multicomponent systems, incorporation of minor elements in mantle phases was mostly studied on a qualitative level. The influence of such elements on structural peculiarities of high-pressure phases is poorly investigated, although incorporation of even small portions of them may have a certain impact on the PT-parameters of phase transformations. Titanium is one of such elements with the low bulk concentrations in the Earth's mantle (0.2 wt % TiO2) [1]; however, Ti-rich lithologies may occur in the mantle as a result of oceanic crust subduction. Thus, the titanium content is 0.6 wt% in Global Oceanic Subducted Sediments (GLOSS) [2], and 1.5 wt% TiO2, in MORB [3]. In this regard, accumulation of titanium in the Earth's mantle is related to crust-mantle interaction during the subduction of crustal material at different depths of the mantle. Experimental methods At 10-24 GPa and 1600°C, we studied the full range of the starting materials in the MgSiO3 (En) - MgTiO3 (Gkl) system in increments of 10-20 mol% Gkl and 1-3 GPa, which allowed us to plot the phase PX diagram for the system MgSiO3-MgTiO3 and synthesize titanium-bearing phases with a wide compositional range. The experiments were performed using a 2000-t Kawai-type multi-anvil high-pressure apparatus at the Geodynamics Research Center, Ehime University (Japan). The quenched samples were examined by single-crystal X-ray diffractometer, and the composition of phases was analyzed using SEM-EDS. Results The main phases obtained in experiments were rutile, wadsleyite, MgSiO3-enstatite, MgTiO3-ilmenite, MgTiSi2O7 with the weberite structure type (Web), Mg(Si,Ti)O3 and MgSiO3 with perovskite-type structure. At a pressure of 13 GPa for Ti-poor bulk compositions, an association of En+Wad+Rt is replaced by the

  2. Experience melting through the Earth's lower mantle via LH-DAC experiments on MgO-SiO2 and CaO-MgO-SiO2 systems

    Science.gov (United States)

    Baron, Marzena A.; Lord, Oliver T.; Walter, Michael J.; Trønnes, Reidar G.

    2015-04-01

    system CaO-MgO-SiO2 (CMS). The eutectic melting temperatures (Te) were determined by multi-chamber DAC-experiments on near-eutectic compositions [3,9]. Ultra-fine W-powder mixed into the samples absorbed the laser energy. The samples were heated at a rate of 500-1500 K/min by increasing the laser power. More than 75-90% eutectic melt is produced at the the solidus, resulting in rapid aggregation of the W-powder and inefficient laser energy absorption. The resulting plateau in the temperature versus power curve is interpreted as Te. Our preliminary results show an expected positive p-Te correlation, with lower Te for the CMS-system. The dTe/dp slope for the bm-silica eutectic is lower than for the bm-pc eutectic in the MS-system. The experimental results agree with the DFT-studies and thermodynamic models. We have also developed a novel technique for micro-fabrication of metal-encapsulated samples (Re, W, Mo), to investigate more precisely the melting phase relations in the lower mantle pressure range. The metal-covered, 20 μm thick sample disc, placed between thermal insulation layers in the DAC, will be laser-heated at the two flat surfaces, providing low thermal gradients and preventing reaction between the sample and the pressure medium. [1] Lay and Garnero (2007, AGU Monograph); [2] Labrosse et al (2007, Nature); [3] Liebske and Frost (2012, EPSL); [4] Elkins-Tanton (2012, Ann Rev Earth Planet Sci); [5] Hirose et al (1999, Nature); [6] Fiquet et al (2010, Science); [7] Andrault et al (2011, EPSL); [8] Andrault et al (2014, Science); [9] de Koker et al (2013, EPSL); [10] de Koker and Strixrude (2009, Geophys J Int).

  3. Calcium phosphate-gold nanoparticles nanocomposite for protein adsorption and mediator-free H{sub 2}O{sub 2} biosensor construction

    Energy Technology Data Exchange (ETDEWEB)

    Xu Qin [College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China); Jiangsu Key Laboratory of Environmental Engineering and Monitoring, Yangzhou 225002 (China); Lu Guiju; Bian XiaoJun; Jin Gendi [College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China); Wang Wei [School of Chemical and Biological Engineering, Yancheng Institute of Technology, Yancheng, 224051 (China); Hu Xiaoya, E-mail: xyhu@yzu.edu.cn [College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China); Jiangsu Key Laboratory of Environmental Engineering and Monitoring, Yangzhou 225002 (China); Wang Yang; Yang Zhanjun [College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China)

    2012-04-01

    This work reports a new method for the preparation and application of a kind of biocompatible calcium phosphate-gold nanoparticles (Ca{sub 3}(PO{sub 4}){sub 2}-AuNPs) nanocomposite. UV-vis spectroscopy and transmittance electron microscopy (TEM) have been used to monitor the formation process of the nanocomposite and to examine the interaction between calcium phosphate and gold nanoparticles (AuNPs). The nanocomposite has multiple sites and improved conductivity which make it suitable for the binding of proteins to construct electrochemical sensors. Myoglobin (Mb) adsorbed on the nanocomposite retained its native structure which was proved by Fourier transform infrared spectroscopy (FTIR). Direct electron transfer between the adsorbed Mb and the electrode was observed. Further results demonstrated that the adsorbed Mb has good electrocatalytic activity towards the reduction of H{sub 2}O{sub 2} in the absence of any mediator. Highlights: Black-Right-Pointing-Pointer Using gelatin modified gold nanoparticles to prepare needle-like calcium phosphate. Black-Right-Pointing-Pointer Calcium phosphate provides multiple sites for protein adsorption. Black-Right-Pointing-Pointer Gold nanoparticles act as electron tunneling. Black-Right-Pointing-Pointer Myoglobin adsorbed on the material showed direct electrochemistry and good catalysis.

  4. Raman and optical absorption spectroscopic investigation of Yb-Er codoped phosphate glasses containing SiO2

    Institute of Scientific and Technical Information of China (English)

    Youkuo Chen; Lei Wen; Lili Hu; Wei Chen; Y. Guyot; G. Boulon

    2009-01-01

    Yb-Er codoped Na2O-Al2O3-P2Os-xSiO2 glasses containing 0 鈥? 20 mol% SiO2 were prepared successfully. The addition of SiO2 to the phosphate glass not only lengthens the bond between P5+ and non-bridging oxygen but also reduces the number of P=O bond. In contrast with silicate glass in which there is only four-fold coordinated Si4+, most probably there coexist [SiO4] tetrahedron and [SiO6] octahedron in our glasses. Within the range of 0 鈥? 20 mol% SiO2 addition, the stimulated emission cross-section of Er3+ ion only decreases no more than 10%. The Judd-Ofelt intensity parameters of Er3+, 惟.2 does not change greatly, but 惟74 and 惟6 decrease obviously with increasing SiO2 addition, because the bond between Er + and O2- is more strongly covalently bonded.

  5. High-Temperature Heat Capacity of Germanates Pr2Ge2O7 and Nd2Ge2O7 within 350-1000 K

    Science.gov (United States)

    Denisova, L. T.; Irtyugo, L. A.; Beletskii, V. V.; Belousova, N. V.; Denisov, V. M.

    2018-03-01

    Pr2Ge2O7 and Nd2Ge2O7 were obtained via solid-phase synthesis from Pr2O3 ( Nd2O3) and GeO2 with multistage firing in air within 1273-1473 K. A temperature effect on molar heat capacity of the oxide compounds was measured with a differential scanning calorimetry. Their thermodynamic properties were calculated from the C P = f( T) dependences.

  6. Hydrothermal synthesis and characterization of a new three-dimensional hybrid zinc phosphate [Zn2(HPO4)2(4,4'-bipy)].3H2O with neutral porous framework

    International Nuclear Information System (INIS)

    Wang Lei; Yang Ming; Li Guanghua; Shi Zhan; Feng Shouhua

    2006-01-01

    Employing 4,4'-bipyridine as a bridged ligand, a new three-dimensional (3-D) hybrid zinc phosphate [Zn 2 (HPO 4 ) 2 (4,4'-bipy)].3H 2 O has been prepared under hydrothermal conditions and characterized by single crystal X-ray diffraction. This compound crystallizes in the monoclinic space group C2/c, with cell parameters, a=21.188(4)A, b=10.229(2)A, c=9.0656(18)A, β=90.21(3) o , V=1964.8(7)A 3 and Z=4. The connectivity of the ZnO 3 N and HPO 4 tetrahedra results in a 2-D neutral layer that with interesting 4,8 2 net along the bc plane. Furthermore, the 4,4'-bipyridine molecule links the 4,8 2 net into a 3-D structure. The water molecules sit in the middle of the channels and interact with the framework via hydrogen bonds. The compound exhibits intense photoluminescence at room temperature

  7. Systems Li[sub 2]B[sub 4]O[sub 7] (Na[sub 2]B[sub 4]O[sub 7], K[sub 2]B[sub 4]O[sub 7])-N[sub 2]H[sub 3]H[sub 4]OH-H[sub 2]O at 25 deg C. Sistemy Li[sub 2]B[sub 4]O[sub 7] (Na[sub 2]B[sub 4]O[sub 7], K[sub 2]B[sub 4]O[sub 7])-N[sub 2]H[sub 3]H[sub 4]OH-H[sub 2]O pri 25 grad S

    Energy Technology Data Exchange (ETDEWEB)

    Skvortsov, V G; Sadetdinov, Sh V; Akimov, V M; Mitrasov, Yu N; Petrova, O V; Klopov, Yu N [Chuvashskij Gosudarstvennyj Pedagogicheskij Inst., Cheboksary (Russian Federation) Universitet Druzhby Narodov, Moscow (Russian Federation)

    1994-02-01

    Phase equilibriums in the Li[sub 2]B[sub 4]O[sub 7] (Na[sub 2]B[sub 4]O[sub 7], K[sub 2]B[sub 4]O[sub 7])-N[sub 2]H[sub 3]H[sub 4]OH-H[sub 2]O systems were investigated by methods of isothermal solubility, refractometry and PH-metry at 25 deg C for the first time. Lithium and sodium tetraborates was established to form phases of changed composition mM[sub 2]B[sub 4]O[sub 7][center dot]nN[sub 2]H[sub 3]C[sub 2]H[sub 4]OH[center dot]XH[sub 2]O, where M=Li, Na with hydrazine ethanol. K[sub 2]B[sub 4]O[sub 7][center dot]4H[sub 2]O precipitates in solid phase in the case of potassium salt. Formation of isomorphous mixtures was supported by X-ray diffraction and IR spectroscopy methods.

  8. Variable dimensionality and new uranium oxide topologies in the alkaline-earth metal uranyl selenites AE[UO2)(SeO3)2] (AE=Ca, Ba) and Sr[UO2)(SeO3)2] · 2H2O

    International Nuclear Information System (INIS)

    Almond, Philip M.; Peper, Shane M.; Bakker, Eric; Albrecht-Schmitt, Thomas E.

    2002-01-01

    Three new alkaline-earth metal uranyl selenites, Ca[UO 2 )(SeO 3 ) 2 ] (1), Sr[UO 2 )(SeO 3 ) 2 ] · 2H 2 O (2), and Ba[UO 2 )(SeO 3 ) 2 ] (3), have been prepared from the reactions of CaCO 3 and Ca(OH) 2 , SrCl 2 and Sr(OH) 2 , or BaCl 2 and Ba(OH) 2 with UO 3 and SeO 2 under mild hydrothermal conditions. Single-crystal X-ray diffraction experiments reveal that the structures of 1-3 differ in both connectivity and dimensionality even though all contain the same fundamental building unit, namely [UO 2 (SeO 3 ) 4 ]. This polyhedron consists of a linear uranyl unit that is bound by one chelating and three bridging selenite anions creating a pentagonal bipyramidal environment around the U(VI) center. The crystal structure of 1 contains one-dimensional ribbons where the edges are terminated by monodentate selenite anions. The interior of the ribbons are constructed from edge-sharing pentagonal bipyramidal UO 7 units. The structure of 2 is also one-dimensional; however, here there are chains of edge-sharing pentagonal bipyramidal UO 7 dimers that are connected by bridging selenite anions. Ba[(UO 2 )(SeO 3 ) 2 ] (3) is two-dimensional, and the highly ruffled anionic sheets present in this structure are formed from both bridging and chelating/bridging selenite anions bound to uranyl moieties. The anionic substructures in 1-3 are separated by Ca 2+ , Sr 2+ , or Ba 2+ cations. Crystallographic data (193 K, MoKα, λ=0.71073): 1, triclinic, space group P1-bar, a=5.5502(6) A, b=6.6415(7) A, c=11.013(1) A, α=104.055(2) deg., β=93.342(2) deg., γ=110.589(2) deg. , Z=2, R(F)=4.56% for 100 parameters with 1530 reflections with I>2σ(I); 2, triclinic, space group P1-bar, a=7.0545(5) A, b=7.4656(5) A, c=10.0484(6) A, α=106.995(1) deg., β=108.028(1) deg., γ=98.875(1) deg., Z=2, R(F)= 2.43% for 128 parameters with 2187 reflections with I>2σ(I); 3, monoclinic, space group P2 1 /c, a=7.3067(6) A, b=8.1239(7) A, c=13.651(1) A, β=100.375(2) deg., Z=4, R(F)=4.31% for 105 parameters

  9. Co-sequestration of Zn(II) and phosphate by γ-Al{sub 2}O{sub 3}: From macroscopic to microscopic investigation

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Xuemei [School of Environment and Chemical Engineering, North China Electric Power University, Beijing 102206 (China); Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, 230031, Hefei (China); Tan, Xiaoli [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, 230031, Hefei (China); Hayat, Tasawar [Department of Mathematics, Quaid-I-Azam University, Islamabad 44000 (Pakistan); NAAM Research Group, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Alsaedi, Ahmed [NAAM Research Group, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Wang, Xiangke, E-mail: xkwang@ipp.ac.cn [School of Environment and Chemical Engineering, North China Electric Power University, Beijing 102206 (China); NAAM Research Group, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions (China)

    2015-10-30

    Highlights: • How the Zn and phosphate behave in each other’s presence is elucidated. • Surface speciation of Zn(II) is affected by the presence of phosphate. • Combining macroscopic study with EXAFS can determine the Zn(II) surface speciation. • The enhanced Zn(II) sorption is mainly due to ternary surface complexation at 0.19 mmol P/L and pH 6.5. • Phosphate ions prevent the formation of an Zn–Al LDH phase at pH 8.0. - Abstract: Little information is available concerning co-sorbing oxyanion and metal contaminants in the environment, yet in most metal-contaminated areas, co-contamination by phosphate is common. In this study, the mutual effects of phosphate and Zn(II) on their interaction with γ-Al{sub 2}O{sub 3} are investigated by batch experiments and X-ray absorption fine structure spectroscopy (XAFS) technique. The results show that the co-sorption of phosphate on γ-Al{sub 2}O{sub 3} modifies both the extent of Zn(II) sorption and the local atomic structures of sorbed Zn(II) ions. Multiple mechanisms are involved in Zn(II) retention in the presence of phosphate, including electrostatic interaction, binary and ternary surface complexation, and the formation of Zn(II)-phosphate polynuclear complexes. At pH 6.5, type III ternary surface complexation occurs concurrently with binary Zn-alumina surface complexation at low phosphate concentrations, whereas the formation of type III ternary surface complexes is promoted as the phosphate concentration increases. With further increasing phosphate concentration, Zn(II)-phosphate polynuclear complexes are formed. At pH 8.0, Zn dominantly forms type III ternary surface complexes in the presence of phosphate. The results of this study indicate the variability of Zn complexation on oxide surface and the importance of combining macroscopic observations with XAFS capable of determining metal complex formation mechanism for ternary system.

  10. High-precision determination of 18O/16O ratios of silver phosphate by EA-pyrolysis-IRMS continuous flow technique.

    Science.gov (United States)

    Lécuyer, Christophe; Fourel, François; Martineau, François; Amiot, Romain; Bernard, Aurélien; Daux, Valérie; Escarguel, Gilles; Morrison, John

    2007-01-01

    A high-precision, and rapid on-line method for oxygen isotope analysis of silver phosphate is presented. The technique uses high-temperature elemental analyzer (EA)-pyrolysis interfaced in continuous flow (CF) mode to an isotopic ratio mass spectrometer (IRMS). Calibration curves were generated by synthesizing silver phosphate with a 13 per thousand spread in delta(18)O values. Calibration materials were obtained by reacting dissolved potassium dihydrogen phosphate (KH(2)PO(4)) with water samples of various oxygen isotope compositions at 373 K. Validity of the method was tested by comparing the on-line results with those obtained by classical off-line sample preparation and dual inlet isotope measurement. In addition, silver phosphate precipitates were prepared from a collection of biogenic apatites with known delta(18)O values ranging from 12.8 to 29.9 per thousand (V-SMOW). Reproducibility of +/- 0.2 per thousand was obtained by the EA-Py-CF-IRMS method for sample sizes in the range 400-500 microg. Both natural and synthetic samples are remarkably well correlated with conventional (18)O/(16)O determinations. Silver phosphate is a very stable material and easy to degas and, thus, could be considered as a good candidate to become a reference material for the determination of (18)O/(16)O ratios of phosphate by high-temperature pyrolysis. Copyright 2006 John Wiley & Sons, Ltd.

  11. Magnetic properties and structural transitions of fluorite-related rare earth osmates Ln{sub 3}OsO{sub 7} (Ln=Pr, Tb)

    Energy Technology Data Exchange (ETDEWEB)

    Hinatsu, Yukio, E-mail: hinatsu@sci.hokudai.ac.jp [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Doi, Yoshihiro [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan)

    2013-02-15

    Ternary rare-earth osmates Ln{sub 3}OsO{sub 7} (Ln=Pr, Tb) have been prepared. They crystallize in an ortho-rhombic superstructure of cubic fluorite with space group Cmcm. Both of these compounds undergo a structural phase transition at 130 K (Ln=Pr) and 580 K (Ln=Tb). These compounds show complex magnetic behavior at low temperatures. Pr{sub 3}OsO{sub 7} exhibits magnetic transitions at 8 and 73 K, and Tb{sub 3}OsO{sub 7} magnetically orders at 8 and 60 K. The Os moments become one-dimensionally ordered, and when the temperature is furthermore decreased, it provokes the ordering in the Ln{sup 3+} sublattice that simultaneously becomes three-dimensionally ordered with the Os sublattice. - Graphical abstract: Ternary rare-earth osmates Ln{sub 3}OsO{sub 7} (Ln=Pr, Tb) have been prepared. They crystallize in an orthorhombic superstructure of cubic fluorite with space group Cmcm. Both of these compounds undergo a structural phase transition at 130 K (Ln=Pr) and 580 K (Ln=Tb). These compounds show complex magnetic behavior at low temperatures. Pr{sub 3}OsO{sub 7} exhibits magnetic transitions at 8 and 73 K, and Tb{sub 3}OsO{sub 7} magnetically orders at 8 and 60 K. Highlights: Black-Right-Pointing-Pointer Ternary rare-earth osmates Ln{sub 3}OsO{sub 7} (Ln=Pr, Tb) with an ordered defect-fluorite structure have been prepared. Black-Right-Pointing-Pointer Both of these compounds undergo a structural phase transition at 130 K (Ln=Pr) and 580 K (Ln=Tb). Black-Right-Pointing-Pointer These compounds show complex magnetic behavior at low temperatures due to magnetic ordering of Ln and Os.

  12. Photo-Induced conductivity of heterojunction GaAs/Rare-Earth doped SnO2

    Directory of Open Access Journals (Sweden)

    Cristina de Freitas Bueno

    2013-01-01

    Full Text Available Rare-earth doped (Eu3+ or Ce3+ thin layers of tin dioxide (SnO2 are deposited by the sol-gel-dip-coating technique, along with gallium arsenide (GaAs films, deposited by the resistive evaporation technique. The as-built heterojunction has potential application in optoelectronic devices, because it may combine the emission from the rare-earth-doped transparent oxide, with a high mobility semiconductor. Trivalent rare-earth-doped SnO2 presents very efficient emission in a wide wavelength range, including red (in the case of Eu3+ or blue (Ce3+. The advantage of this structure is the possibility of separation of the rare-earth emission centers, from the electron scattering, leading to an indicated combination for electroluminescence. Electrical characterization of the heterojunction SnO2:Eu/GaAs shows a significant conductivity increase when compared to the conductivity of the individual films. Monochromatic light excitation shows up the role of the most external layer, which may act as a shield (top GaAs, or an ultraviolet light absorber sink (top RE-doped SnO2. The observed improvement on the electrical transport properties is probably related to the formation of short conduction channels in the semiconductors junction with two-dimensional electron gas (2DEG behavior, which are evaluated by excitation with distinct monochromatic light sources, where the samples are deposited by varying the order of layer deposition.

  13. Reductions in mitochondrial O(2) consumption and preservation of high-energy phosphate levels after simulated ischemia in chronic hibernating myocardium.

    Science.gov (United States)

    Hu, Qingsong; Suzuki, Gen; Young, Rebeccah F; Page, Brian J; Fallavollita, James A; Canty, John M

    2009-07-01

    We performed the present study to determine whether hibernating myocardium is chronically protected from ischemia. Myocardial tissue was rapidly excised from hibernating left anterior descending coronary regions (systolic wall thickening = 2.8 +/- 0.2 vs. 5.4 +/- 0.3 mm in remote myocardium), and high-energy phosphates were quantified by HPLC during simulated ischemia in vitro (37 degrees C). At baseline, ATP (20.1 +/- 1.0 vs. 26.7 +/- 2.1 micromol/g dry wt, P < 0.05), ADP (8.1 +/- 0.4 vs. 10.3 +/- 0.8 micromol/g, P < 0.05), and total adenine nucleotides (31.2 +/- 1.3 vs. 40.1 +/- 2.9 micromol/g, P < 0.05) were depressed compared with normal myocardium, whereas total creatine, creatine phosphate, and ATP-to-ADP ratios were unchanged. During simulated ischemia, there was a marked attenuation of ATP depletion (5.6 +/- 0.9 vs. 13.7 +/- 1.7 micromol/g at 20 min in control, P < 0.05) and mitochondrial respiration [145 +/- 13 vs. 187 +/- 11 ng atoms O(2).mg protein(-1).min(-1) in control (state 3), P < 0.05], whereas lactate accumulation was unaffected. These in vitro changes were accompanied by protection of the hibernating heart from acute stunning during demand-induced ischemia. Thus, despite contractile dysfunction at rest, hibernating myocardium is ischemia tolerant, with reduced mitochondrial respiration and slowing of ATP depletion during simulated ischemia, which may maintain myocyte viability.

  14. Synthesis of condensed double rubidium manganese phosphates in melts of polyphosphoric acids

    International Nuclear Information System (INIS)

    Guzeeva, L.S.; Tananaev, I.V.

    1988-01-01

    The aim of this work was to study the character of the reaction of MnO 2 and Rb 2 O with melts of polyphosphoric acids, and to establish the composition and the conditions of formation of the condensed double rubidium manganese phosphates. In the reaction of manganese and rubidium oxides with melts of polyphosphoric acids at 140-350 degree C, three types of trivalent manganese and rubidium condensed double phosphates are formed - diphosphates RbMn(H 2 P 2 O 7 ) and Rb 2 MnH 3 (P 2 O 7 ) 2 , triphosphate RbMnHP 3 O 10 and diphosphate RbMnP 2 O 7 - in addition to a double cyclotriphosphate of divalent manganese with rubidium RbMnP 3 O 9 . The thermal transformations of the compound isolated were studied. It was shown that rubidium manganese cyclotriphosphate can be obtained by the thermal decomposition of the diphosphate RbMn(H 2 P 2 O 7 ) 2

  15. A Study on Electrochemical Reduction of Rare Earth Oxides in Molten LiCl-Li2O Salt

    International Nuclear Information System (INIS)

    Lee, Min Woo; Jeong, Sang Mun; Lee, See Hoon; Sohn, Jung Min

    2016-01-01

    In this study, the electrochemical reduction of RE 2 O 3 (RE = Nd or Ce) has been conducted via co-reduction NiO to increase the reduction degree of the rare earth oxides in molten molten LiCl containing 1wt% Li 2 O. The electrochemical reduction behavior of the mixed RE 2 O 3 -NiO oxide has been investigated and the reduction path of RE 2 O 3 has been proposed. An electorchemical spent fuel processing technology, pyroprocessing, has been developed for recycling of spent fuel to be applied to a sodium-cooled fast reactor. The spent fuel is reduced in the oxide reduction process. It is well known that the rare earth oxides are hardly reduced due to their electrochemical and thermodynamic stability. The rare earth oxides unreduced in the reduction process can cause problems via reaction with UCl 3 in the electrorefiner. To tackle those problems, the electrochemical reduction of rare earth oxide has been conducted via co-reduction of NiO in LiCl molten salt containing 1 wt% Li 2 O. The reduction of the oxide mixture starts from the reduction of NiO to Ni, followed by that of RE 2 O 3 on the produced Ni to form intermetallic RENi 5 . The mixed oxide pellets were successfully reduced to the RENi5 alloy by constant electrolysis at 3.0 V at 650 .deg. C. The crucial aspect to these results is that the thermodynamically stable rare-earth oxide, Nd 2 O 3 was successfully converted to the metal in the presence of NiO.

  16. Yttrium aluminum garnet (YAG) obtained by rare-earth mixed oxide (RE2O3)

    International Nuclear Information System (INIS)

    Castro, D.F.; Daguano, J.K.M.F.; Rodrigues Junior, D.; Suzuki, P.A.; Silva, O.M.M.

    2010-01-01

    In this work, the substitution of commercial Y 2 O 3 by a rare earth mixed oxide, RE 2 O 3 , to form Yttrium aluminum Garnet-Y 3 Al 5 O 12 , was investigated. Al 2 O 3 :Y 2 O 3 and Al 2 O 3 :RE 2 O 3 powder-mixtures, in a molar ratio of 60:40, were milled and subsequently cold uniaxially-pressed. Compacts were sintered at 1000, 1400 or 1600 deg C, for 120 minutes. RE 2 O 3 oxide was characterized by high-resolution synchrotron X-ray diffraction (HRXRD) and compared to Y 2 O 3 . X-ray diffraction pattern of the RE 2 O 3 indicates a true solid solution formation. Rietveld refinement of the sintered YAG and (RE)AG reveled a similar crystal structure to the YAGs obtained by the use of Al 2 O 3 -Y 2 O 3 or Al 2 O 3 -RE 2 O 3 respectively. Microstructural analysis of both, YAG or (RE)AG, revealed similar grain sizes of about 2.5 μm besides mechanical properties, with hardness of 400HV and fracture toughness of 3.8MPa.m1/2. It could be, thus, demonstrated that pure Y 2 O 3 can be substituted by the rare-earth solid solution, RE 2 O 3 , in the formation YAGs, presenting similar microstructural and mechanical properties. (author)

  17. Stability and anisotropy of (FexNi1-x)2O under high pressure and implications in Earth's and super-Earths' core.

    Science.gov (United States)

    Huang, Shengxuan; Wu, Xiang; Qin, Shan

    2018-01-10

    Oxygen is thought to be an important light element in Earth's core but the amount of oxygen in Earth's core remains elusive. In addition, iron-rich iron oxides are of great interest and significance in the field of geoscience and condensed matter physics. Here, static calculations based on density functional theory demonstrate that I4/mmm-Fe 2 O is dynamically and mechanically stable and becomes energetically favorable with respect to the assemblage of hcp-Fe and [Formula: see text]-FeO above 270 GPa, which indicates that I4/mmm-Fe 2 O can be a strong candidate phase for stable iron-rich iron oxides at high pressure, perhaps even at high temperature. The elasticity and anisotropy of I4/mmm-(Fe x Ni 1-x ) 2 O at high pressures are also determined. Based on these results, we have derived the upper limit of oxygen to be 4.3 wt% in Earth's lower outer core. On the other hand, I4/mmm-(Fe x Ni 1-x ) 2 O with high AV S is likely to exist in a super-Earth's or an ocean planet's solid core causing the locally seismic heterogeneity. Our results not only give some clues to explore and synthesize novel iron-rich iron oxides but also shed light on the fundamental information of oxygen in the planetary core.

  18. Assessment for the role of rare earth oxide in the R2O3 - RuO2 - Pt composite electrode

    International Nuclear Information System (INIS)

    Do Ngoc Lien; Nguyen Van Sinh

    2004-01-01

    Our work has showed several results related to assessment for the role of rare earth oxide in the R 2 O 3 - RuO 2 - Pt composite electrode. The precursor method was used for preparing composite electrode in the following forms: a- RuO 2 - Pt electrode b- La 2 O 3 (55%) - RuO 2 (45%) - Pt electrode c- CeO 2 (60%) - RuO 2 (40%) - Pt electrode By measurements of anodic polarization and cyclic potential for the types of a, b, c electrodes we can see that the La 2 O 3 (55%) - 45% RuO 2 - Pt electrode will be the best anodic electrode. It means that the partial replacement of ruthenium oxide by lanthanum oxide in composite oxide electrode will be an effective one. (author)

  19. Catalase activity is stimulated by H2O2 in rich culture medium and is required for H2O2 resistance and adaptation in yeast ☆

    OpenAIRE

    Martins, Dorival; English, Ann M.

    2014-01-01

    Catalases are efficient scavengers of H2O2 and protect cells against H2O2 stress. Examination of the H2O2 stimulon in Saccharomyces cerevisiae revealed that the cytosolic catalase T (Ctt1) protein level increases 15-fold on H2O2 challenge in synthetic complete media although previous work revealed that deletion of the CCT1 or CTA1 genes (encoding peroxisomal/mitochondrial catalase A) does not increase the H2O2 sensitivity of yeast challenged in phosphate buffer (pH 7.4). This we attributed to...

  20. Spectroscopic identification of rare earth elements in phosphate glass

    Science.gov (United States)

    Devangad, Praveen; Tamboli, Maktum; Muhammed Shameem, K. M.; Nayak, Rajesh; Patil, Ajeetkumar; Unnikrishnan, V. K.; Santhosh, C.; Kumar, G. A.

    2018-01-01

    In this work, rare earth-doped phosphate glasses were synthesized and characterized using three different spectroscopic techniques. The absorption spectra of the prepared praseodymium (Pr) and samarium (Sm) doped glasses, recorded by a UV-VIS-NIR spectrophotometer, show the characteristic absorption bands of these elements. To confirm this inference, laser-induced fluorescence spectra of Pr and Sm were obtained at a laser excitation of 442 nm. Their emission bands are reported here. The elemental analysis of these samples was carried out using a laser-induced breakdown spectroscopy (LIBS) system. Characteristic emission lines of Pr and Sm have been identified and reported by the recorded LIBS spectra of glass samples. Results prove that using these three complimentary spectroscopic techniques (absorption, fluorescence and LIBS), we can meaningfully characterize rare earth-doped glass samples.

  1. Structure and properties of gadolinium loaded calcium phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Cuiling [Analytical and Testing Center, Southwest University of Science and Technology, Mianyang 621010 (China); State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Liang, Xiaofeng, E-mail: XFLiang@swust.edu.cn [Analytical and Testing Center, Southwest University of Science and Technology, Mianyang 621010 (China); State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Li, Haijian; Yu, Huijun; Li, Zhen [Analytical and Testing Center, Southwest University of Science and Technology, Mianyang 621010 (China); State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Yang, Shiyuan [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China)

    2014-10-15

    The glass samples with composition xGd{sub 2}O{sub 3}–(50 − x)CaO–50P{sub 2}O{sub 5} (0 ⩽ x ⩽ 9 mol%) were prepared by the conventional melt quench method. The structure and properties of gadolinium loaded in calcium phosphate glasses were investigated using XRD, SEM, DTA, IR and Raman spectroscopy. The XRD and SEM analysis for the samples show that the majority of samples are amorphous, and crystallization occurs when the content of Gd{sub 2}O{sub 3} containing is up to 6 mol%. Two main crystalline phases, Ca{sub 2}P{sub 2}O{sub 7} and Gd{sub 3}(P{sub 2}O{sub 7}){sub 3}, are embedded in an amorphous matrix. IR and Raman data indicate that glass structure consists of predominantly metaphosphate (Q{sup 2}) units and the depolymerization of phosphate network with the addition of Gd{sub 2}O{sub 3}. Both the chemical durability and the glass transition temperature (T{sub g}) are improved with the increase of Gd{sub 2}O{sub 3}, which suggests that the Gd acts a role of strengthening the cross-links between the phosphate chains of the glass.

  2. Rare earth elements in sedimentary phosphate deposits: Solution to the global REE crisis?

    Science.gov (United States)

    Emsbo, Poul; McLaughlin, Patrick I.; Breit, George N.; du Bray, Edward A.; Koenig, Alan E.

    2015-01-01

    The critical role of rare earth elements (REEs), particularly heavy REEs (HREEs), in high-tech industries has created a surge in demand that is quickly outstripping known global supply and has triggered a worldwide scramble to discover new sources. The chemical analysis of 23 sedimentary phosphate deposits (phosphorites) in the United States demonstrates that they are significantly enriched in REEs. Leaching experiments using dilute H2SO4 and HCl, extracted nearly 100% of their total REE content and show that the extraction of REEs from phosphorites is not subject to the many technological and environmental challenges that vex the exploitation of many identified REE deposits. Our data suggest that phosphate rock currently mined in the United States has the potential to produce a significant proportion of the world's REE demand as a byproduct. Importantly, the size and concentration of HREEs in some unmined phosphorites dwarf the world's richest REE deposits. Secular variation in phosphate REE contents identifies geologic time periods favorable for the formation of currently unrecognized high-REE phosphates. The extraordinary endowment, combined with the ease of REE extraction, indicates that such phosphorites might be considered as a primary source of REEs with the potential to resolve the global REE (particularly for HREE) supply shortage.

  3. Syntheses and Thermal Behaviors of Rb(FOX-7)·H2O and Cs(FOX-7)·H2O

    International Nuclear Information System (INIS)

    Luo, Jinan; Xu, Kangzhen; Wang, Min; Ren, Xiaolei; Chen, Yongshun; Song, Jirong; Zhao, Fengqi

    2010-01-01

    Two new energetic organic alkali metal salts, 1,1-diamino-2,2-dinitroethylene rubidium salt [Rb(FOX-7)·H 2 O] and 1,1- diamino-2,2-dinitroethylene cesium salt [Cs(FOX-7)·H 2 O], were synthesized by reacting of 1,1-diamino-2,2-dinitroethylene (FOX-7) and rubidium chloride or cesium chloride in alkali methanol aqueous solution, respectively. The thermal behaviors of Rb(FOX-7)·H 2 O and Cs(FOX-7)·H 2 O were studied with DSC and TG methods. The critical temperatures of thermal explosion of the two compounds are 216.22 and 223.73 .deg. C, respectively. Specific heat capacities of the two compounds were determined with a micro-DSC method, and the molar heat capacities are 217.46 and 199.47 J mol -1 K -1 at 298.15 K, respectively. The adiabatic times-to-explosion were also calculated to be a certain value of 5.81 - 6.36 s for Rb(FOX-7)·H 2 O, and 9.92 - 10.54 s for Cs(FOX-7)·H 2 O. After FOX-7 becoming alkali metal salts, thermal decomposition temperatures of the compounds heighten with the rise of element period, but thermal decomposition processes become intense

  4. Air Plasma-Sprayed La2Zr2O7-SrZrO3 Composite Thermal Barrier Coating Subjected to CaO-MgO-Al2O3-SiO2 (CMAS)

    Science.gov (United States)

    Cai, Lili; Ma, Wen; Ma, Bole; Guo, Feng; Chen, Weidong; Dong, Hongying; Shuang, Yingchai

    2017-08-01

    La2Zr2O7-SrZrO3 composite thermal barrier coatings (TBCs) were prepared by air plasma spray (APS). The La2Zr2O7-SrZrO3 composite TBCs covered with calcium-magnesium-aluminum-silicate (CMAS) powder, as well as the powder mixture of CMAS and spray-dried La2Zr2O7-SrZrO3 composite powder, were heat-treated at 1250 °C in air for 1, 4, 8, and 12 h. The phase constituents and microstructures of the reaction products were characterized by x-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. Experimental results showed that the La2Zr2O7-SrZrO3 composite TBCs had higher CMAS resistance than 8YSZ coating. A dense new layer developed between CMAS and La2Zr2O7-SrZrO3 composite TBCs during interaction, and this new layer consisted mostly of apatite (Ca2La8(SiO4)6O2) and c-ZrO2. The newly developed layer effectively protected the La2Zr2O7-SrZrO3 composite TBCs from further CMAS attack.

  5. Transport properties of YBa2Cu3O7/PrBa2Cu3O7 superlattices

    International Nuclear Information System (INIS)

    Jakob, G.; Hahn, T.; Stoelzel, C.; Tome-Rosa, C.; Adrian, H.

    1992-01-01

    We investigated the transport properties of high-quality YBa 2 Cu 3 O 7 /PrBa 2 Cu 3 O 7 superlattices. The exceptional structural order of the superlattices resulted in satellite peaks up to the ninth order in X-ray diffraction diagrams and high Tc values. We find high superconducting critical transport current densities j c even for ultrafine modulated superlattices which proves the existence of nearly continuous YBa 2 Cu 3 O 7 layers. The activation energy U is found to be constant or to have a linear temperatures dependence over a wide temperature range. (orig.)

  6. Geochemical exploration for phosphate in the State of Acre

    International Nuclear Information System (INIS)

    Costa, M.L. da; Melo Costa, W.A. de; Santos, A.J.M. dos

    1989-01-01

    The geochemical prospecting conducted for phosphates in Acre which could explain the good fertility of the region was charged to discover this material. The phosphates are strictly built of all the bone structures and coprolites of the several fragments of vertebrate fossils, which are widespread in the region. The phosphatic fossils are bedded in the Solimoes Formation, especially its basal to intermediary conglomeratic bed. The fossils are constituted of low crystallinity apatite, and their matrix sediments include quartz, feldspars, smectite, halloysite and calcite. The P 2 O 5 content reaches up to 5% in the sediments and up to 32% in the fragments. The fossils are enriched in U 3 O 8 and rare earth elements. There is no perspect of classic or mineral deposits but the geological knowlwdge will permit the improvement of the use of the soils in Acre. (author) [pt

  7. Physical and optical properties of calcium sulfate ultra-phosphate glass-doped Er2O3

    Science.gov (United States)

    Aliyu, Aliyu Mohammed; Hussin, R.; Deraman, Karim; Ahmad, N. E.; Danmadami, Amina M.; Yamusa, Y. A.

    2018-03-01

    The influence of erbium on physical and optical properties of calcium sulfate ultra-phosphate glass was investigated using conventional melt quench process. Selected samples of composition 20CaSO4 (80 - x) P2O5- xEr2O3 with 0.1 ≤x ≤ 0.9 mol.% were prepared and assessed. X-ray diffraction (XRD) techniques were used to confirm the amorphous nature of the said samples. The structural units of phosphate-based glass were assessed from Raman spectra as ultra-(Q3), meta-(Q2), pyro-(Q1) and orthophosphate (Q0) units. Depolymerization process of the glasses was testified for higher calcium oxide content and UV-visible for optical measurement. Thermal analysis have been investigated by means of thermogravimetric analysis. The results show the decomposition of materials in the temperature range of 25∘C-1000∘C. Er3+ absorption spectra were measured in the range of 400-1800nm. PL measurement was carried out in order to obtain the excitation and emission spectra of the samples. The emission spectra excited at 779nm comprises of 518nm, 550nm and 649nm of transition 4F9/2, 4S3/2 and 2H11/2 excited states to 4I15/2 ground state. In physical properties, the density calculated using Archimedes method is inversely proportional to molar volume with increase in Er3+ ions. Optical bandgap (Eg) were determined using Tauc’s plots for direct transitions where Eg (direct) decreases with increase in erbium content. The refractive index increases with decreasing molar volume; this may have a tendency for larger optical bandgap. The result obtained from the glass matrix indicates that erbium oxide-doped calcium sulfate ultra-phosphate may give important information for wider development of functional glasses.

  8. Partitioning of the rare earths and actinides between R7T7 nuclear glass alteration products and solution according to disposal conditions

    International Nuclear Information System (INIS)

    Menard, O.

    1995-01-01

    The alteration of nuclear glass by water is liable to release radionuclides into the environment. Determining the release kinetics of these elements and their aqueous chemical forms are therefore essential steps in establishing the safety of a geological repository site. Leach tests were conducted with a nonradioactive specimen of the French ''R7T7'' light water containment glass spiked with U and Th, and with two R7T7 specimens spiked with 237 Np and 239 Pu, respectively. The alteration solution compositions were representative of deep groundwater and contained carbonate, sulfate, phosphate, fluorine and chlorine ions. The release of U, Th, Np and Pu, as well as of the rare earths La, Ce and Nd were monitored by ICP mass spectrometry and by α spectrometry. Scanning and transmission electron microscopic examination of the nonradioactive altered glass surfaces was also performed to assess the partitioning balance for the rare earths, U and Th between the glass alteration products and solution. The mobility of these elements depends on two competing mechanisms. The rare earths and thorium are incorporated in the alteration products (gel); the retention process is assumed to involve chemisorption or coprecipitation, enhanced in the gel layer by the presence of phosphate ions in particular. Conversely, the aqueous species in the alteration solutions (mainly anions) form complexes with the actinides and rare earths; this phenomenon is particularly evident with U and Np. The presence of carbonate ions favors this mobility. Plutonium differs from U and Np in that it is adsorbed mainly on colloids formed by glass dissolution, the principal factors governing its chemical evolution in solution. (author). refs., 122 figs., 185 tabs

  9. Structural and sensing characteristics of Gd2Ti2O7, Er2TiO5 and Lu2Ti2O7 sensing membrane electrolyte–insulator–semiconductor for bio-sensing applications

    International Nuclear Information System (INIS)

    Pan, Tung-Ming; Liao, Pei-You; Chang, Kung-Yuan; Chi, Lifeng

    2013-01-01

    Highlights: ► The structural and sensing properties of Gd 2 Ti 2 O 7 , Er 2 TiO 5 and Lu 2 Ti 2 O 7 sensing films grown on Si substrates by reactive co-sputtering. ► The EIS device incorporating a Lu 2 Ti 2 O 7 sensing film exhibited a higher sensitivity, a larger drift rate, a higher hysteresis voltage, and a larger hysteresis gap than other sensing films. ► The impedance effect of EIS sensors has been investigated using C–V method. -- Abstract: This paper describes the structural and sensing characteristics of Gd 2 Ti 2 O 7 , Er 2 TiO 5 , and Lu 2 Ti 2 O 7 sensing membranes deposited on Si substrates through reactive co-sputtering for electrolyte–insulator–semiconductor (EIS) pH sensors. In this work, the structural properties of Gd 2 Ti 2 O 7 , Er 2 TiO 5 , and Lu 2 Ti 2 O 7 membranes were investigated by X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy. The observed structural properties were then correlated with the resulting pH sensing performances. The EIS device incorporating a Lu 2 Ti 2 O 7 sensing film exhibited a higher sensitivity (59.32 mV pH −1 ), a larger drift rate (0.55 mV h −1 ), a higher hysteresis voltage (5 mV), and a larger hysteresis gap (∼70 mV) compared to those of the other sensing films. This result is attributed to the higher surface roughness and the formation of a thicker interfacial layer at the oxide–Si interface. Furthermore, the impedance effect of EIS sensors has been investigated using capacitance–voltage (C–V) method (frequency-dependent C–V curves). From the impedance spectroscopy analysis, we find that the diameter of a semicircle of an EIS sensor becomes smaller due to a gradual decrease in the bulk resistance of the device with degree of pH value

  10. Exposure to tri-o-cresyl phosphate detected in jet airplane passengers.

    Science.gov (United States)

    Liyasova, Mariya; Li, Bin; Schopfer, Lawrence M; Nachon, Florian; Masson, Patrick; Furlong, Clement E; Lockridge, Oksana

    2011-11-01

    The aircraft cabin and flight deck ventilation are supplied from partially compressed unfiltered bleed air directly from the engine. Worn or defective engine seals can result in the release of engine oil into the cabin air supply. Aircrew and passengers have complained of illness following such "fume events". Adverse health effects are hypothesized to result from exposure to tricresyl phosphate mixed esters, a chemical added to jet engine oil and hydraulic fluid for its anti-wear properties. Our goal was to develop a laboratory test for exposure to tricresyl phosphate. The assay was based on the fact that the active-site serine of butyrylcholinesterase reacts with the active metabolite of tri-o-cresyl phosphate, cresyl saligenin phosphate, to make a stable phosphorylated adduct with an added mass of 80 Da. No other organophosphorus agent makes this adduct in vivo on butyrylcholinesterase. Blood samples from jet airplane passengers were obtained 24-48 h after completing a flight. Butyrylcholinesterase was partially purified from 25 ml serum or plasma, digested with pepsin, enriched for phosphorylated peptides by binding to titanium oxide, and analyzed by mass spectrometry. Of 12 jet airplane passengers tested, 6 were positive for exposure to tri-o-cresyl phosphate that is, they had detectable amounts of the phosphorylated peptide FGEpSAGAAS. The level of exposure was very low. No more than 0.05 to 3% of plasma butyrylcholinesterase was modified. None of the subjects had toxic symptoms. Four of the positive subjects were retested 3 to 7 months following their last airplane trip and were found to be negative for phosphorylated butyrylcholinesterase. In conclusion, this is the first report of an assay that detects exposure to tri-o-cresyl phosphate in jet airplane travelers. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Preparation of rare earth fluorides from apatite concentrate

    International Nuclear Information System (INIS)

    Mulyarchuk, I.F.; Voloshchenko, M.V.; Zen'kovich, E.G.; Sumenkova, V.V.; AN Ukrainskoj SSR, Kiev. Inst. Problem Lit'ya)

    1980-01-01

    The processes of preparation of the rare earths element sum from apatite concentrate of the Khibins, connected with preliminary extraction of rare earth phosphates from nitric acid extract using solvent extraction or direct precipitation from the extract by solution of potassium and ammonium fluorides. The sequence of the processes of the first variant is the following: solvent extraction of rare earths by tributylphosphate from clarified nitric acid extract of apatite with subsequent reextraction of rare earths with water and precipitation of rare earth phosphates from aqueous solution during neutralization by ammonia. In case of fluoride preparation from rare earth phosphate the main attention is paid to precipitation and filtration of fluorides. Technological scheme and cost price of industry for the production of 1800 t of rare earth trifluorides a year are calculated. When taking account of TBP losses according to its solubility the industry cost price is 1O times lower the modern cost of rare earth fluorides

  12. Preparation and bioactivity of micro-arc oxidized calcium phosphate coatings

    International Nuclear Information System (INIS)

    Pan, Y.K.; Chen, C.Z.; Wang, D.G.; Lin, Z.Q.

    2013-01-01

    Calcium phosphate (CaP) coatings were prepared on ZK60 magnesium alloy by micro-arc oxidation (MAO) in electrolyte containing calcium acetate monohydrate (CH 3 COO) 2 Ca·H 2 O) and disodium hydrogen phosphate dodecahydrate (Na 2 HPO 4 ·12H 2 O). Scanning electron microscope (SEM), energy-dispersive X-ray spectrometry (EDX) and X-ray diffractometer (XRD) were employed to characterize the microstructure, elemental distribution and phase composition of the CaP coatings respectively. Simulated body fluid (SBF) immersion test was used to evaluate the coating degradability and bioactivity. After 30 days of SBF immersion, the CaP coatings effectively reduce the degradation rate. The surfaces of CaP coatings are covered by a new layer formed of numerous needle-like, spherical and columned calcium phosphates. SEM, EDX and XRD results suggest that these calcium phosphates are bioactive calcium phosphate phases such as hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 , HA) and calcium pyrophosphates (Ca 2 P 2 O 7 , CPP). The formation of these calcium phosphates indicates that the CaP coatings have bioactivity. - Highlights: • Bioactive CaP coatings are successfully formed on ZK60 magnesium alloy. • CaP coatings consist of MgO, MgF 2 , CaO, CaF 2 and Ca 3 (PO 4 ) 2 . • Needle-like, spherical and columned calcium phosphates formed in SBF. • CaP coatings exhibit bioactivity and low corrosion rate

  13. Preparation and characterization of TiO2 and Si-doped octacalcium phosphate composite coatings on zirconia ceramics (Y-TZP) for dental implant applications

    Science.gov (United States)

    Bao, Lei; Liu, Jingxiao; Shi, Fei; Jiang, Yanyan; Liu, Guishan

    2014-01-01

    In order to prevent the low temperature degradation and improve the bioactivity of zirconia ceramic implants, TiO2 and Si-doped octacalcium phosphate composite coating was prepared on zirconia substrate. The preventive effect on low temperature degradation and surface morphology of the TiO2 layer were studied. Meanwhile, the structure and property changes of the bioactive coating after doping Si were discussed. The results indicate that the dense TiO2 layer, in spite of some microcracks, inhibited the direct contact of the water vapor with the sample's surface and thus prevented the low temperature degradation of zirconia substrates. The acceleration aging test shows that the ratio of the monoclinic phase transition decreased from 10% for the original zirconia substrate to 4% for the TiO2-coated substrate. As to the Si-doped octacalcium phosphate coating prepared by biomimetic method, the main phase composition of the coating was octacalcium phosphate. The morphology of the coating was lamellar-like, and the surface was uniform and continuous with no cracks being observed. It is suggested that Si was added into the coating both through substituting for PO43- and doping as NaSiO3.

  14. Synthesis of rare-earth selenate and selenite materials under 'sol-gel' hydrothermal conditions: crystal structures and characterizations of La(HSeO3)(SeO4) and KNd(SeO4)2

    International Nuclear Information System (INIS)

    Liu Wei; Chen Haohong; Yang Xinxin; Li Mangrong; Zhao Jingtai

    2004-01-01

    Two rare-earth compounds containing selenium atoms, La(HSeO 3 )(SeO 4 ) with a new open framework structure and KNd(SeO 4 ) 2 with a layered structure, have been synthesized under ''sol-gel'' hydrothermal conditions for the first time. Single-crystals of La(HSeO 3 )(SeO 4 ) crystallize in the monoclinic system (P2 1 , a=8.5905(17)A, b=7.2459(14)A, c=9.5691(19)A, β=104.91(3) o , Z=2, RAll=0.032). The structure contains puckered polyhedral layers made of LaO x (x=9,10) and SeO 4 groups, which are connected via SeO 3 -uints to the 3D structure. The crytal structure of KNd(SeO 4 ) 2 (monoclinc, P2 1 /c, a=8.7182(17)A, b=7.3225(15)A, c=11.045(2)A, β=91.38(3) o , Z=4, RAll=0.051) contains honeycomb-like six-ring NdO 9 polyhedra forming layers which are further decorated with SeO 4 tetrahedra. The K + ions occupy the interspaces of these layers and provide the charge balance

  15. A preliminary X-ray study of sedoheptulose-7-phosphate isomerase from Burkholderia pseudomallei

    International Nuclear Information System (INIS)

    Kim, Mi-Sun; Shin, Dong Hae

    2009-01-01

    Sedoheptulose-7-phosphate isomerase (GmhA) from B. pseudomallei is one of the targets of antibiotic adjuvants for melioidosis. In this study, GmhA has been cloned, expressed, purified and crystallized. Sedoheptulose-7-phosphate isomerase (GmhA) converts d-sedoheptulose 7-phosphate to d,d-heptose 7-phosphate. This is the first step in the biosynthesis pathway of NDP-heptose, which is responsible for the pleiotropic phenotype. This biosynthesis pathway is the target of inhibitors to increase the membrane permeability of Gram-negative pathogens or of adjuvants working synergistically with known antibiotics. Burkholderia pseudomallei is the causative agent of melioidosis, a seriously invasive disease in animals and humans in tropical and subtropical areas. GmhA from B. pseudomallei is one of the targets of antibiotic adjuvants for melioidosis. In this study, GmhA has been cloned, expressed, purified and crystallized. Synchrotron X-ray data were also collected to 1.9 Å resolution. The crystal belonged to the primitive orthorhombic space group P2 1 2 1 2 1 , with unit-cell parameters a = 61.3, b = 84.2, c = 142.3 Å. A full structural determination is under way in order to provide insights into the structure–function relationships of this protein

  16. A Study on Electrochemical Reduction of Rare Earth Oxides in Molten LiCl-Li{sub 2}O Salt

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Min Woo; Jeong, Sang Mun; Lee, See Hoon [Chungbook National University, Chungju (Korea, Republic of); Sohn, Jung Min [Chonbuk National University, Jeonju (Korea, Republic of)

    2016-05-15

    In this study, the electrochemical reduction of RE{sub 2}O{sub 3} (RE = Nd or Ce) has been conducted via co-reduction NiO to increase the reduction degree of the rare earth oxides in molten molten LiCl containing 1wt% Li{sub 2}O. The electrochemical reduction behavior of the mixed RE{sub 2}O{sub 3}-NiO oxide has been investigated and the reduction path of RE{sub 2}O{sub 3} has been proposed. An electorchemical spent fuel processing technology, pyroprocessing, has been developed for recycling of spent fuel to be applied to a sodium-cooled fast reactor. The spent fuel is reduced in the oxide reduction process. It is well known that the rare earth oxides are hardly reduced due to their electrochemical and thermodynamic stability. The rare earth oxides unreduced in the reduction process can cause problems via reaction with UCl{sub 3} in the electrorefiner. To tackle those problems, the electrochemical reduction of rare earth oxide has been conducted via co-reduction of NiO in LiCl molten salt containing 1 wt% Li{sub 2}O. The reduction of the oxide mixture starts from the reduction of NiO to Ni, followed by that of RE{sub 2}O{sub 3} on the produced Ni to form intermetallic RENi{sub 5}. The mixed oxide pellets were successfully reduced to the RENi5 alloy by constant electrolysis at 3.0 V at 650 .deg. C. The crucial aspect to these results is that the thermodynamically stable rare-earth oxide, Nd{sub 2}O{sub 3} was successfully converted to the metal in the presence of NiO.

  17. FeO and H-2O and the homogeneous accretion of the earth

    Science.gov (United States)

    Lange, M. A.; Ahrens, T. J.

    1983-01-01

    Shock devolatilization recovery data for brunite (Mg(OH)2) shocked to 13 and 23 GPa are presented. These data combined with previous data for serpentine (Mg3Si2O5(OH)4) are used to constrain the minimum size terrestrial planet for which planetesimal infall will result in an impact generated water atmosphere. Assuming, in hydrous phyllosilicates, model calculations simulating the interaction of metallic iron with impact released free water on the surface of the accreting Earth were carried out. It is assumed that the reaction of water with iron in the presence of enstatite is the prime source of the terrestrial FeO component of silicates and oxides. Lower and upper bounds on the terrestrial FeO budget are based on mantle FeO content and possible incorporation of FeO in the outer core. We demonstrate that the iron water reaction would result in the absence of atmospheric/hydrospheric water, if homogeneous accretion is assumed.

  18. FeO and H2O and the homogeneous accretion of the earth

    Science.gov (United States)

    Lange, M. A.; Ahrens, T. J.

    1984-01-01

    Shock devolatilization recovery data for brunite (Mg(OH)2) shocked to 13 and 23 GPa are presented. These data combined with previous data for serpentine (Mg3Si2O5(OH)4) are used to constrain the minimum size terrestrial planet for which planetesimal infall will result in an impact generated water atmosphere. Assuming, in hydrous phyllosilicates, model calculations simulating the interaction of metallic iron with impact released free water on the surface of the accreting earth were carried out. It is assumed that the reaction of water with iron in the presence of enstatite is the prime source of the terrestrial FeO component of silicates and oxides. Lower and upper bounds on the terrestrial FeO budget are based on mantle FeO content and possible incorporation of FeO in the outer core. We demonstrate that the iron water reaction would resuit in the absence of atmospheric/hydrospheric water, if homogeneous accretion is assumed.

  19. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO2 fiber

    International Nuclear Information System (INIS)

    Katsumata, Toru; Morita, Kentaro; Komuro, Shuji; Aizawa, Hiroaki

    2014-01-01

    Visible light thermal radiation from SiO 2 glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO 2 fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO 2 fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900 K. Peak intensities of thermal radiations from rare-earth doped SiO 2 fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO 2 fibers are smaller than those from SiO 2 fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO 2 are potentially applicable for the fiber-optic thermometry above 900 K

  20. Magnetic properties and structural transitions of fluorite-related rare earth osmates Ln3OsO7 (Ln=Pr, Tb)

    Science.gov (United States)

    Hinatsu, Yukio; Doi, Yoshihiro

    2013-02-01

    Ternary rare-earth osmates Ln3OsO7 (Ln=Pr, Tb) have been prepared. They crystallize in an ortho-rhombic superstructure of cubic fluorite with space group Cmcm. Both of these compounds undergo a structural phase transition at 130 K (Ln=Pr) and 580 K (Ln=Tb). These compounds show complex magnetic behavior at low temperatures. Pr3OsO7 exhibits magnetic transitions at 8 and 73 K, and Tb3OsO7 magnetically orders at 8 and 60 K. The Os moments become one-dimensionally ordered, and when the temperature is furthermore decreased, it provokes the ordering in the Ln3+ sublattice that simultaneously becomes three-dimensionally ordered with the Os sublattice.

  1. Solubilities of some hydrous REE phosphates with implications for diagenesis and sea water concentrations

    International Nuclear Information System (INIS)

    Jonasson, R.G.; Bancroft, G.M.; Nesbitt, H.W.

    1985-01-01

    Solubility product determinations suggest that the hydrous phosphates of the rare earths, REPO 4 .xH 2 O, are important in controlling the sea water REE concentrations. Two of these solids, rhabdophane, (P6 2 22) and 'hydrous xenotime', (I4 1 /amd), have been synthesized at 100 C via the acid hydrolysis of the respective REE pyrophosphate. The solubility products at infinite dilution were determined to be pK 0 = 24.5, (La at 25 C); 26.0, (Pr at 100 C); 25.7, (Nd at 100 C); and 25.5, (Er at 100 C). On the basis of calculations involving the reaction of Re 3+ with apatite to form the hydrous phosphate, the lanthanum concentration in sea water is predicted to be about 140 pmol/L. Laboratory experiments support the hypothesis that apatite is a substrate for reactions with dissolved REE. (author)

  2. Microwave properties of YBa2Cu3O7-δ/PrBa2Cu3O7-δ superlattices

    International Nuclear Information System (INIS)

    Carlos, W.E.; Kaplan, R.; Lowndes, D.H.; Norton, D.P.

    1992-01-01

    We have used non-resonant microwave absorption to study c-axis YBa 2 Cu 3 O 7-δ /PrBa 2 Cu 3 O 7-δ superlattices and compare the response to a film of similarly grown YBa 2 Cu 3 O 7-δ (YBCO). Near the respective transition temperatures, the response of the superlattice samples and the YBCO film have similar amplitudes and orientation dependences. This is consistent with the microwave loss being related to magnetic flux penetration at (110) slip planes. At lower temperatures, the response of the superlattices is much stronger than that of the YBCO film and, while both responses are hysteretic at low temperatures, the widths of the hysteresis have opposite orientation dependences, which we attribute to the role of the PrBa 2 Cu 3 O 7-δ layers. (orig.)

  3. Epitaxial YBa2Cu3O7-δ/Sr2RuO4 heterostructures

    International Nuclear Information System (INIS)

    Schlom, D.G.; Merritt, B.A.; Madhavan, S.

    1997-01-01

    The anisotropic oxide superconductors YBa 2 Cu 3 O 7-δ and Sr 2 RuO 4 have been epitaxially combined in various ways (c-axis on c-axis, c-axis on a-axis, and a-axis on a-axis) though the use of appropriate substrates. Phase-pure a-axis oriented or c-axis oriented epitaxial Sr 2 RuO 4 films were grown by pulsed laser deposition. YBa 2 Cu 3 O 7-δ films were then grown on both orientations of Sr 2 RuO 4 films and the resulting epitaxy was characterized

  4. Preparation and bioactivity of micro-arc oxidized calcium phosphate coatings

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Y.K. [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Ji' nan, Shandong 250061 (China); School of Materials Science and Engineering, Shandong University, Ji' nan, Shandong 250061 (China); Chen, C.Z., E-mail: czchen@sdu.edu.cn [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Ji' nan, Shandong 250061 (China); School of Materials Science and Engineering, Shandong University, Ji' nan, Shandong 250061 (China); Wang, D.G.; Lin, Z.Q. [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Ji' nan, Shandong 250061 (China); School of Materials Science and Engineering, Shandong University, Ji' nan, Shandong 250061 (China)

    2013-09-16

    Calcium phosphate (CaP) coatings were prepared on ZK60 magnesium alloy by micro-arc oxidation (MAO) in electrolyte containing calcium acetate monohydrate (CH{sub 3}COO){sub 2}Ca·H{sub 2}O) and disodium hydrogen phosphate dodecahydrate (Na{sub 2}HPO{sub 4}·12H{sub 2}O). Scanning electron microscope (SEM), energy-dispersive X-ray spectrometry (EDX) and X-ray diffractometer (XRD) were employed to characterize the microstructure, elemental distribution and phase composition of the CaP coatings respectively. Simulated body fluid (SBF) immersion test was used to evaluate the coating degradability and bioactivity. After 30 days of SBF immersion, the CaP coatings effectively reduce the degradation rate. The surfaces of CaP coatings are covered by a new layer formed of numerous needle-like, spherical and columned calcium phosphates. SEM, EDX and XRD results suggest that these calcium phosphates are bioactive calcium phosphate phases such as hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}, HA) and calcium pyrophosphates (Ca{sub 2}P{sub 2}O{sub 7}, CPP). The formation of these calcium phosphates indicates that the CaP coatings have bioactivity. - Highlights: • Bioactive CaP coatings are successfully formed on ZK60 magnesium alloy. • CaP coatings consist of MgO, MgF{sub 2}, CaO, CaF{sub 2} and Ca{sub 3}(PO{sub 4}){sub 2}. • Needle-like, spherical and columned calcium phosphates formed in SBF. • CaP coatings exhibit bioactivity and low corrosion rate.

  5. A new three-dimensional cobalt phosphate: Co5(OH2)4(HPO4)2(PO4)2

    International Nuclear Information System (INIS)

    Han Zhangang; Tian Aixiang; Peng Jun; Zhai Xueliang

    2006-01-01

    A three-dimensional (3D) cobalt phosphate: Co 5 (OH 2 ) 4 (HPO 4 ) 2 (PO 4 ) 2 (1), has been synthesized by hydrothermal reaction and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic techniques. The title compound is a template free cobalt phosphate. Compound 1 exhibits a complex net architecture based on edge- and corner-sharing of CoO 6 and PO 4 polyhedra. The magnetic susceptibility measurements indicated that the title compound obeys Curie-Weiss behavior down to a temperature of 17 K at which an antiferromagnetic phase transition occurs. - Graphical abstract: A 3D cobalt phosphate with a neutral framework: Co 5 (OH 2 ) 4 (HPO 4 ) 2 (PO 4 ) 2 (1), has been synthesized and characterized. Compound 1 exhibits a complex net architecture based on edge- and corner-sharing of CoO 6 and PO 4 polyhedra. Its magnetic property was researched

  6. New compounds bearing [M(S_2O_7)_3]"2"- anions (M = Si, Ge, Sn): Syntheses and characterization of A_2[Si(S_2O_7)_3] (A = Na, K, Rb), A_2[Ge(S_2O_7)_3] (A = Li, Na, K, Rb, Cs), A_2[Sn(S_2O_7)_3] (A = Na, K), and the unique germanate Hg_2[Ge(S_2O_7)_3]Cl_2 with cationic "1_∞[HgCl_2_/_2]"+ chains

    International Nuclear Information System (INIS)

    Logemann, Christian; Witt, Julia; Wickleder, Mathias S.; Gunzelmann, Daniel; Senker, Juergen

    2012-01-01

    The reaction of the group 14 tetrachlorides MCl_4 (M = Si, Ge, Sn) with oleum (65 % SO_3) at elevated temperatures led to the unique anionic complexes [M(S_2O_7)_3]"2"- that show the central M atoms in coordination of three chelating S_2O_7"2"- groups. The mean distances M-O within the complexes increase from 175 pm (M = Si) via 186 pm (M = Ge) up to 200 pm (M = Sn). The charge balance for the [M(S_2O_7)_3]"2"- anions is achieved by alkaline metal ions A"+ (A = Li, Na, K, Rb, Cs) which were implemented in the syntheses in form of their sulfates. The size of the A"+ ions, i.e. their coordination requirement causes the crystallographic differences in the crystal structures, while the structure of the complex [M(S_2O_7)_3]"2"- anions remains essentially unaffected. Furthermore, we were able to characterize the unique germanate Hg_2[Ge(S_2O_7)_3]Cl_2 which forms when HgCl_2 is added as a source for the counter cation. The Hg"2"+ and the Cl"- ions form infinite cationic chains according to "1_∞[HgCl_2_/_2]"+ which take care for the charge compensation. For selected examples of the compounds the thermal behavior has been monitored by means of thermal analyses and X-ray powder diffraction. For A being an alkaline metal the decomposition product is a mixture of the sulfates A_2SO_4 and the dioxides MO_2, whereas Hg_2[Ge(S_2O_7)_3]Cl_2 shows a more complicated decomposition. The tris-(disulfato)-silicate Na_2[Si(S_2O_7)_3] has additionally been examined by solid state "2"9Si and "2"3Na NMR spectroscopic measurements. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Room temperature synthesis and photocatalytic property of AgO/Ag2Mo2O7 heterojunction nanowires

    International Nuclear Information System (INIS)

    Hashim, Muhammad; Hu, Chenguo; Wang, Xue; Wan, Buyong; Xu, Jing

    2012-01-01

    Graphical abstract: The AgO nanoparticles are attached on the surface of the Ag 2 Mo 2 O 7 nanowires to form a heterojunction structure. The AgO nanoparticles start embedding into the nanowires with increasing reaction temperature or time. Highlights: ► AgO/Ag 2 Mo 2 O 7 heterojunction NWs were synthesized at room temperature for the first time. ► AgO particles embed into the Ag 2 Mo 2 O 7 NWs with increase in reaction time and temperature. ► The heterojunction NWs display much better photocatalytic activity than the none-heterojunction NWs. ► The catalytic mechanism was proposed. -- Abstract: AgO/Ag 2 Mo 2 O 7 heterojunction nanowires were synthesized at temperatures of 25 °C, 50 °C, 80 °C, and 110 °C, under magnetic stirring in solution reaction. The catalytic activity of AgO/Ag 2 Mo 2 O 7 nanowires was evaluated by the degradation of Rhodmine B dye under the irradiation of the simulated sunlight. The synthesized samples were characterized by X-ray diffractometer, energy dispersive spectrometry, X-ray photoelectron spectrometer, scanning electron microscopy, and transmission electron microscopy. The results show that the AgO nanoparticles are attached on the surface of the Ag 2 Mo 2 O 7 nanowires to form a heterojunction structure. The length of the nanowires is up to 10 μm and the size of the AgO nanoparticles is 10–20 nm. The length of nanowires increases with increasing reaction time and temperature while the AgO particles are gradually embedded into the nanowires. The photocatalytic activity is greatly improved for the AgO/Ag 2 Mo 2 O 7 heterojunction nanowires compared with that of the pure Ag 2 Mo 2 O 7 nanowires, indicating a remarkable role of AgO particles on the Ag 2 Mo 2 O 7 nanowires in the photodegradation.

  8. Microbial Leaching of Some Valuable Elements From Egyptian Phosphate Rock

    International Nuclear Information System (INIS)

    Kamal, H.M.; Hassanein, R.A.; Mahdy, H.M.A.; Mahmoud, K.F.; Abouzeid, M.A.

    2012-01-01

    Four phosphate rock samples representing different phosphate mineralization modes in Egypt were selected from Abu Tartar, Nile valley and Red sea areas. Factors affecting the phosphate rock solubilization and some of the contained valuable elements by Aspergillus niger, Penicillium sp. and Pseudomonas fluorescence, were studied with especial orientation towards the completion of phosphate rock samples solubilization especially die low grade one. Effect of nitrogen source type on leaching efficiency by Aspergillus niger when two nitrogen sources on the phosphate bioleaching efficiency, it is clear that the ammonium chloride is more favorable as nitrogen source than sodium nitrate in the bioleaching of phosphate rocks. When Aspergillus niger was applied under die following conditions: 50 g/1 of sucrose as a carbon source, 0.1 N of ammonium chloride as a nitrogen source, 10 days incubation period, 0.5% solid: liquid ratio for P 2 O 5 and 5% for U and REE and - 270 mesh of grain size. The optimum leaching of P 2 O 5 , U and REE from phosphate rock samples reached (23.27%, 17.4%, 11.4%, respectively), while at -60 mesh they reached to 16.58%, 28.9%, 30.2% respectively. The optimum conditions for the maximal leaching efficiencies of P 2 O 5 , U and REE when applying the Penicillium sp. from the phosphate rock samples were: 100 g/1 of sucrose as a carbon source for P 2 O 5 and U and 10 g/1 for REE, 7,15 and 10 days incubation period for P 2 O 5 , U and REE, respectively, 0.5% solid: liquid ratio for P 2 O 5 and 5% for U and REE. Finally, the application of phosphate rock samples grinded to -270 mesh of grain size for P 2 O 5 and (-60 to -140) for U and REE. The studied leaching efficiency of P 2 O 5 , U and REE gave at -270 mesh 33.66%, 24.3%, 15.9% respectively, while at -60 mesh they gave 33.76%, 26.7%, 17.8% and at -140 mesh gave 31.32%, 27.9%, 17.6%, respectively.The optimum conditions for the P 2 O 5 leaching efficiency when applying the Pseudomonas fluorescence were

  9. Novel 2D or 3D alkaline-earth metal sulfonate-phosphonates based on [O 3S-C 2H 4-PO 3H] 2- ligand

    Science.gov (United States)

    Du, Zi-Yi; Wen, He-Rui; Xie, Yong-Rong

    2008-11-01

    Three novel alkaline-earth metal sulfonate-phosphonates based on [O 3S-C 2H 4-PO 3H] 2- ligand, namely, [Ca(O 3SC 2H 4PO 3H)(H 2O) 2] ( 1), [Sr(O 3SC 2H 4PO 3H)] ( 2) and [Ba 2(O 3SC 2H 4PO 3H) 2] ( 3), have been synthesized by hydrothermal reactions. They represent the first structurally characterized alkaline-earth metal complexes of phosphonic acid attached with a sulfonate group. The structure of compound 1 features a 2D layer based on 1D chains of [Ca 2(PO 3) 2] bridged by -CH 2-CH 2-SO 3- groups. Compounds 2 and 3 show pillar-layer architecture based on two different inorganic layers linked by -CH 2-CH 2- groups. The inorganic layer in compound 2 features a 1D chain of edge-sharing SrO 8 polyhedra whereas that in compound 3 features an edge-sharing Ba 2O 14 di-polyhedral unit which is further corner-shared with four neighboring ones. The [O 3S-C 2H 4-PO 3H] 2- ligand shows diverse coordination modes in the three alkaline-earth metal sulfonate-phosphonates.

  10. Redetermination of clinobarylite, BaBe2Si2O7

    Directory of Open Access Journals (Sweden)

    Adrien J. Di Domizio

    2012-10-01

    Full Text Available Clinobarylite, ideally BaBe2Si2O7 (chemical name barium diberyllium disilicate, is a sorosilicate mineral and dimorphic with barylite. It belongs to a group of compounds characterized by the general formula BaM2+2Si2O7, with M2+ = Be, Mg, Fe, Mn, Zn, Co, or Cu, among which the Be-, Fe-, and Cu-members have been found in nature. The crystal structure of clinobarylite has been re-examined in this study based on single-crystal X-ray diffraction data collected from a natural sample from the type locality (Khibiny Massif, Kola Peninsula, Russia. The structure of clinobarylite can be considered as a framework of BeO4 and SiO4 tetrahedra, with one of the O atoms coordinated to two Be and one Si, one coordinated to two Si, and two O atoms coordinated to one Si and one Be atom. The BeO4 tetrahedra share corners, forming chains parallel to the c axis, which are interlinked by the Si2O7 units oriented parallel to the a axis. The Ba2+ cations (site symmetry m.. are in the framework channels and are coordinated by eleven O atoms in form of an irregular polyhedron. The Si—Obr (bridging O atom, at site symmetry m.. bond length, the Si—Onbr (non-bridging O atoms bond lengths, and the Si—O—Si angle within the Si2O7 unit are in marked contrast to the corresponding values determined in the previous study [Krivovichev et al. (2004. N. Jb. Miner. Mh. pp. 373–384].

  11. Thermal decomposition of heavy rare-earth butanoates, Ln(C3H7CO2)3 (Ln = Er, Tm, Yb and Lu) in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Tang, Xiao

    2016-01-01

    was observed in all four compounds, but its course depends on the rare-earth element. Decomposition to sesquioxides proceeds via the formation of dioxymonocarbonates (Ln2O2CO3) and release of 4-heptanone (C3H7COC3H7) as well as carbon dioxide (CO2) without evidence for an intermediate oxobutanoate stage...... of Ln2O2CO3 and Ln2O3. The stability of this intermediate state seems to decrease with the mass of the rare-earth elements. Complete conversion to Ln2O3 is reached at about 1100 °C. The overall thermal decomposition behaviour of the title compounds is different from previous reports for other rare....... During the decomposition of Ln2O2CO3 into the respective sesquioxides (Ln2O3), an intermediate plateau extending from approximately 550 to 850 °C appears in the TG traces. The overall composition during this stage corresponds approximately to Ln2O2.8(CO3)0.2, but the state is more probably a mixture...

  12. Structural, optical and spectroscopical investigations into rare-earths perowskites RGaO{sub 3} (R=La, Pr, Nd) and NdBa-2Cu{sub 3}O{sub 7-{delta}}; Strukturelle, optische und spektroskopische Untersuchungen von Seltenen-Erd-Perowskiten RGaO{sub 3} (R=La, Pr, Nd) und NdBa{sub 2}Cu{sub 3}O{sub 7-{delta}}

    Energy Technology Data Exchange (ETDEWEB)

    Marti, W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1995-07-01

    In this work I was engaged in rare-earth perovskites. Primarily I investigated the structure of the rare-earth gallates RGaO{sub 3} (R=La, Pr, Nd) as a function of the temperature by means of neutron diffraction and x-ray diffraction. As the high-T{sub c} superconductors these compounds belong to the family of the perovskites, they are ferroelastic and centro-symmetric. Because of the lanthanide-contraction all lattice constants and distortion parameters change systematically. The rare-earth-gallates RGaO{sub 3} (R=La, Pr, Nd) are promising substrates for epitaxy of high-T{sub c} superconductors like RBa{sub 2}Cu{sub 3}OO{sub 7-{delta}} because of their structure parameters and expansion coefficients. I succeeded in producing plane-parallel single-domain crystals by means of uniaxial stress. The first order phase transition was observable only in LaGaO{sub 3}. A structurally phase transition from orthorhombic to rhombohedral symmetry (high-temperature phase) occurs at 423 K. The hysteresis of the phase transition temperature of about 1.5 K was measured with single-domain crystals by means of neutron diffraction and polarized light microscopy. In NdGaO{sub 3} we determined the long-range, three-dimensional, antiferromagnetic ordering of the Nd{sup 3+}-ions below the ordering temperature at T{sub N}=0.97 K by means of magnetic neutron diffraction. The spin configuration could be described by a (--c{sub z})-mode. Measurements of the magnetic susceptibility confirm the easy direction of magnetization to be the c-axis. Below 300mK an additional nuclear spin polarization due to the hyperfine-interaction appears parallel to the electronic spins, which amounts to 70% at 10mK. Further I investigated the optical properties of the rare-earth gallates. The birefringence of plane-parallel, polished single-domain crystals with thickness up to 300 {mu}m was measured by means of orthoscopy and conoscopy. (author) figs., tabs., refs.

  13. Processing of Phosphorus Slag with Recovery of Rare Earth Metals and Obtaining Silicon Containing Cake

    Science.gov (United States)

    Karshigina, Zaure; Abisheva, Zinesh; Bochevskaya, Yelena; Akcil, Ata; Sharipova, Aynash; Sargelova, Elmira

    2016-10-01

    The present research is devoted to the processing of slag generating during the yellow phosphorus production. In this paper are presented studies on leaching of phosphorus production slag by nitric acid with recovery of rare earth metals (REMs) into solution. REMs recovery into the solution achieved 98 % during the leaching process with using 7.5 mol/L of HNO3, liquid-to-solid ratio is 2.6:1, temperature is 60°C, process duration is 1 hour and stirrer speed is 500 rpm. Behaviour during the leaching of associated components such as calcium, aluminium, and iron was studied. After the leaching cake contains ∼⃒75-85 % of SiO2 and it might be useful for obtaining of precipitated silicon dioxide. With the purpose of separation from the impurities, recovery and concentrating of REMs, the obtained solution after leaching was subjected to extraction processing methods. The influence of ratio of organic and aqueous phases (O: A) on the extraction of rare earth metals by tributyl phosphate (TBP) with concentrations from 20 up to 100 % was studied. The REMs extraction with increasing TBP concentration under changes O:A ratio from 1:20 down to 1:1 into the organic phase from the solutions after nitric acid leaching increased from 22.2 up to 99.3%. The duration effect of REMs extraction process was studied by tributyl phosphate. It is revealed that with increasing of duration of the extraction process from 10 to 30 minutes REMs recovery into the organic phase almost did not changed. The behaviour of iron in the extraction process by TBP was studied. It was found that such accompanying components as calcium and aluminium by tributyl phosphate didn't extracted. To construct isotherm of REMs extraction of by tributyl phosphate was used variable volume method. It was calculated three-step extraction is needed for REMs recovery from the solutions after nitric acid leaching of phosphorus production slag. The process of the three-steps counter current extraction of rare earth

  14. Nimbus-7 Earth radiation budget calibration history. Part 2: The Earth flux channels

    Science.gov (United States)

    Kyle, H. Lee; Hucek, Douglas Richard R.; Ardanuy, Philip E.; Hickey, John R.; Maschhoff, Robert H.; Penn, Lanning M.; Groveman, Brian S.; Vallette, Brenda J.

    1994-01-01

    Nine years (November 1978 to October 1987) of Nimbus-7 Earth radiation budget (ERB) products have shown that the global annual mean emitted longwave, absorbed shortwave, and net radiation were constant to within about + 0.5 W/sq m. Further, most of the small annual variations in the emitted longwave have been shown to be real. To obtain this measurement accuracy, the wide-field-of-view (WFOV) Earth-viewing channels 12 (0.2 to over 50 micrometers), 13 (0.2 to 3.8 micrometers), and 14 (0.7 to 2.8 micrometers) have been characterized in their satellite environment to account for signal variations not considered in the prelaunch calibration equations. Calibration adjustments have been derived for (1) extraterrestrial radiation incident on the detectors, (2) long-term degradation of the sensors, and (3) thermal perturbations within the ERB instrument. The first item is important in all the channels; the second, mainly in channels 13 and 14, and the third, only in channels 13 and 14. The Sun is used as a stable calibration source to monitor the long-term degradation of the various channels. Channel 12, which is reasonably stable to both thermal perturbations and sensor degradation, is used as a reference and calibration transfer agent for the drifting sensitivities of the filtered channels 13 and 14. Redundant calibration procedures were utilized. Laboratory studies complemented analyses of the satellite data. Two nearly independent models were derived to account for the thermal perturbations in channels 13 and 14. The global annual mean terrestrial shortwave and longwave signals proved stable enough to act as secondary calibration sources. Instantaneous measurements may still, at times, be in error by as much as a few Wm(exp -2), but the long-term averages are stable to within a fraction of a Wm(exp -2).

  15. Proton Environments in Biomimetic Calcium Phosphates Formed from Mesoporous Bioactive CaO-SiO2-P2O5 Glasses in Vitro: Insights from Solid-State NMR.

    Science.gov (United States)

    Mathew, Renny; Turdean-Ionescu, Claudia; Yu, Yang; Stevensson, Baltzar; Izquierdo-Barba, Isabel; García, Ana; Arcos, Daniel; Vallet-Regí, María; Edén, Mattias

    2017-06-22

    When exposed to body fluids, mesoporous bioactive glasses (MBGs) of the CaO-SiO 2 -P 2 O 5 system develop a bone-bonding surface layer that initially consists of amorphous calcium phosphate (ACP), which transforms into hydroxy-carbonate apatite (HCA) with a very similar composition as bone/dentin mineral. Information from various 1 H-based solid-state nuclear magnetic resonance (NMR) experiments was combined to elucidate the evolution of the proton speciations both at the MBG surface and within each ACP/HCA constituent of the biomimetic phosphate layer formed when each of three MBGs with distinct Ca, Si, and P contents was immersed in a simulated body fluid (SBF) for variable periods between 15 min and 30 days. Directly excited magic-angle-spinning (MAS) 1 H NMR spectra mainly reflect the MBG component, whose surface is rich in water and silanol (SiOH) moieties. Double-quantum-single-quantum correlation 1 H NMR experimentation at fast MAS revealed their interatomic proximities. The comparatively minor H species of each ACP and HCA component were probed selectively by heteronuclear 1 H- 31 P NMR experimentation. The initially prevailing ACP phase comprises H 2 O and "nonapatitic" HPO 4 2- /PO 4 3- groups, whereas for prolonged MBG soaking over days, a well-progressed ACP → HCA transformation was evidenced by a dominating O 1 H resonance from HCA. We show that 1 H-detected 1 H → 31 P cross-polarization NMR is markedly more sensitive than utilizing powder X-ray diffraction or 31 P NMR for detecting the onset of HCA formation, notably so for P-bearing (M)BGs. In relation to the long-standing controversy as to whether bone mineral comprises ACP and/or forms via an ACP precursor, we discuss a recently accepted structural core-shell picture of both synthetic and biological HCA, highlighting the close relationship between the disordered surface layer and ACP.

  16. Structural and superconducting properties of oxygen-deficient NdBa sub 2 Cu sub 3 O sub 7 minus. delta

    Energy Technology Data Exchange (ETDEWEB)

    Shaked, H. (Nuclear Research Center-Negev, Post Office Box 9001, Beer Sheva, Israel (IL) Ben Gurion University of the Negev, Post Office Box 653, Beer Sheva, Israel (IL)); Veal, B.W.; Faber, J. Jr.; Hitterman, R.L.; Balachandran, U.; Tomlins, G.; Shi, H.; Morss, L.; Paulikas, A.P. (Argonne National Laboratory, Argonne, Illinois 60439 (USA))

    1990-03-01

    Neutron diffraction was used to determine the structural properties of oxygen deficient NdBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} for 0.09{lt}{delta}{lt}0.74. It was found that superconductivity disappears at the orthorhombic-to-tetragonal phase transition which occurs at {delta}{sub {ital O}{ital T}}=0.45. Structural parameters vary smoothly with {delta} but exhibit a change in slope at the orthorhombic-to-tetragonal transition. The structural properties exhibit the same features found in YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} where {delta}{sub {ital O}{ital T}}=0.65. It is shown that the repulsion energy of oxygen atoms in the O(1) and O(5) sites in NdBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} is smaller than in YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. This lower repulsion energy stabilizes the orthorhombic phase at lower values of {delta}. It is argued that the disappearance of superconductivity at the orthorhombic-to-tetragonal transition is an inherent property of the {ital R}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} ({ital R} denotes rare earth) system.

  17. TRANSFORMAÇÃO DO FOSFATO MONOCÁLCICO EM FOSFATO BICÁLCICO TRANSFORMATION OF MONOCALCIC PHOSPHATE IN BICALCIC PHOSPHATE

    Directory of Open Access Journals (Sweden)

    Terezinha de H. B. O. Tocantins

    2007-09-01

    Full Text Available

    O Estado de Goiás é rico em fosfato monocálcico (de baixo preço, o qual é usado como adubo. Com a finalidade de transformá-1o em fosfato bicálcico (de preço elevado e utilizá-lo na alimentação de bovinos, desenvolveu-se nova técnica de obtenção do bicálcico, à partir do monocálcico, e não a partir da rocha fosfático ou da reação do óxido de cálcio com ácido sulfúrico. A metodologia aplicada foi a seguinte: preparo das amostras visando a obtê-las com teores de acidez livre variando de 1 a 6 em função do ácido sulfúrico (amostras estas chamadas de T1, T2, ..... T6 respectivamente. Após obtidos os graus de acidez desejados, iniciaram-se os tratamentos térmicos das mesmas, ou seja, as amostras foram submetidas às temperaturas de 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 260, 280 e 300 graus centígrados durante tempos de exposição de 20, 30 e 40 minutos. Finalmente, as amostras foram analisadas a fim de se obter os teores de P205 solúvel em água e em ácido cítrico a 2%. Pelas aná1ises desses teores, concluiu-se o seguinte: dos tratamentos efetivados, o que apresentou maior eficiência de transformação do fosfato monocálcico para bicálcico foi o denominado de T1 com tempo de exposição de 40 minutos sob a temperatura de 280°C.

    The state of Goiás is rich in monocalcic phosphate, which is used as fertilizer and has low price, in order to change it to bicalcic phosphate, which has high price and is used for cattle feeding. A new technique of bicalcic obtention was developed from the monocalcic, and not from the phosphatic rocks or from the calcium oxide reaction with sulphuric acid. The methodology applied was the following: Preparation of the samples trying to obtain them with contents of free acidity varying from one to six in function of sulphuric acid (samples

  18. Synthesis and thermic behaviour (stability and sintering) of rare earth ortho-phosphates; Synthese et comportement thermique (stabilite et frittage) de phosphates de terres rares ceriques ou yttriques

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, S

    2003-04-01

    Rare earth ortho-phosphates, LnPO{sub 4},nH{sub 2}O (Ln = La, Ce or Y), were synthesized by precipitation in aqueous media. The effect of pH, temperature, reagents stoichiometry and ripening time on the chemical composition and the morphology of the precipitates have been precised. The study of the thermal behaviour showed the presence of meta-phosphates as a secondary phase in the temperature range 1000 C - 1400 C that was very detrimental to the sintering. It is removed by calcining the powders at 1400 C. Thermogravimetry proved to be the best technique in order to insure the purity of the precipitates since it allows the detection of this phase down to a lower threshold than that associated with the other investigated characterization methods (IR or Raman spectrometry, chemical analysis, XRD, DTA). The monazites (La or Ce)PO{sub 4} densify at 1400 C by natural sintering whereas the xenotime YPO{sub 4} is not yet densified at 1500 C. Hot pressing at that temperature is required to its densification. The mechanical properties of the monazites remain low (sf about 120 MPa, K{sub IC} about 1.2 MPa.m{sup 1/2}). The xenotime ceramic is much more mechanically resistant (sf about 320 MPa, K{sub IC} about 1.5 MPa.m{sup 1/2}). An important acicular growth of the grains during the sintering of the xenotime (that occurs also during the synthesis process) is considered to be responsible for the behaviour and properties differences between this material and monazites. (author)

  19. Critical current density in (YBa2Cu3O7-δ)1-x-(PrBa2Cu3O7-δ)x melt-textured composites

    Science.gov (United States)

    Opata, Yuri Aparecido; Monteiro, João Frederico Haas Leandro; Jurelo, Alcione Roberto; Siqueira, Ezequiel Costa

    2018-06-01

    Melt textured (YBa2Cu3O7-δ)1-x-(PrBa2Cu3O7-δ)x composites (x = 0.00 and x = 0.05) were grown using the top seeding method. The effect of the PrBa2Cu3O7-δ phase on the growth process and the modification of the microstructure as well as on the physical properties was analyzed. X-ray analyses indicated that both pure and Pr-doped samples present an orthorhombic superconducting phase. From resistivity measurements for YBa2Cu3O7-δ and (YBa2Cu3O7-δ)0.95-(PrBa2Cu3O7-δ)0.05 samples, the Tcab did not change and was around 90.5 K. However, from magnetic measurements, the superconductivity was observed in critical temperatures TC = 92.9 K and 92.4 K for YBa2Cu3O7-δ and (YBa2Cu3O7-δ)0.95-(PrBa2Cu3O7-δ)0.05 samples, respectively. The YBa2Cu3O7-δ sample showed higher critical current densities than those shown by the (YBa2Cu3O7-δ)0.95-(PrBa2Cu3O7-δ)0.05 sample, with values of JC = 5.85 × 105 A/cm2 and 4.72 × 105 A/cm2, respectively. This paper also discusses the importance of Pr substitution on nano- and micro-meter scales to enhance JC(H).

  20. Synthesis, structural and luminescence properties of Bi3+ co-doped Y2Sn2O7:Tb nanoparticles

    International Nuclear Information System (INIS)

    Nigam, S.; Sudarsan, V.; Vatsa, R.K.

    2010-01-01

    Full text: In recent years, advanced materials derived from Pyrochlore-type oxides (A 2 B 2 O 7 ) have been of extensive scientific and technological interest. Chemical substitution of A or B sites of pyrochlore oxide by rare earth ions is a widely used approach to prepare thermally stable, lanthanide ion doped luminescent materials. Due to the higher symmetry around the A and B sites in the lattice lanthanide ions like Eu 3+ and Tb 3+ when incorporated at the A or B sites give very poor luminescence. This problem can be avoided by incorporating other ions like Bi 3+ in the lattice so that the lattice gets distorted and luminescent intensity from the lanthanide ions increases. The present study deals with the synthesis and characterization of Bi 3+ co-doped Y 2 Sn 2 O 7 :Tb nanoparticles. For the preparation of Tb 3+ and Bi 3+ doped Y 2 Sn 2 O 7 nano-materials, Sn metal, Bi(NO 3 ) 3 , Tb 4 O 7 , Y 2 CO 3 , were used as starting materials. The solution containing Y 3+ , Sn 4+ ,and Bi 3+ -Tb 3+ in ethylene glycol medium was slowly heated up to 120 deg C and then subjected to urea hydrolysis. The obtained precipitate after washing was heated to 700 deg C. As prepared samples are amorphous in nature and 700 deg C heated sample showed well crystalline pyrochlore structure as revealed by the XRD studies. Average particles size is calculated from the width of the X-ray diffraction peaks and found to be ∼ 5 nm. TEM images of the nanoparticles obtained at 700 deg C shows very fine spherical particles having a diameter in the range of 2-5 nm. Luminescence measurements were carried out for as prepared and 700 deg C heated samples of 2.5%Tb doped Y 2 Sn 2 O 7 nanoparticles. Green emission characteristic 5 D 4 7 F 5 transition of Tb 3+ has been observed from as prepared sample but on heating to 700 deg C the emission characteristic of Tb 3+ ions got completely removed . However, there is a significant improvement in Tb 3+ emission from 2.5% Bi 3+ co-doped Y 2 Sn 2 O 7 :Tb 3

  1. Evidence of Coulomb correction and spinorbit coupling in rare-earth dioxides CeO 2, PrO 2 and TbO 2: An ab initio study

    KAUST Repository

    Kanoun, Mohammed; Reshak, A. H.; Kanoun-Bouayed, Nawel; Goumri-Said, Souraya

    2012-01-01

    The current study investigates the structural, elastic, electronic and optical properties of CeO 2, PrO 2 and TbO 2 using the full potential (linearized) augmented plane wave plus local orbital method within the WuCohen generalized gradient approximation (GGA) with Hubbard (U) correction and spinorbit coupling (SOC). The GGAU implementation lead us to describe correctly the relativistic effect on 4f electrons for CeO 2. We clarify that the inclusion of the Hubbard U parameter and the spinorbit coupling are responsible for the ferromagnetic insulating of PrO 2 and TbO 2. The magnetic description is achieved by the spin-density contours and magnetic moment calculations, where we show the polarization of oxygen atoms from the rare earth atoms. The mechanical stability is shown via the elastic constants calculations. The optical properties, namely the dielectric function and the reflectivity are calculated for radiation up to 12 eV, giving interesting optoelectronic properties to these dioxides. © 2011 Elsevier B.V. All rights reserved.

  2. Evidence of Coulomb correction and spinorbit coupling in rare-earth dioxides CeO 2, PrO 2 and TbO 2: An ab initio study

    KAUST Repository

    Kanoun, Mohammed

    2012-04-01

    The current study investigates the structural, elastic, electronic and optical properties of CeO 2, PrO 2 and TbO 2 using the full potential (linearized) augmented plane wave plus local orbital method within the WuCohen generalized gradient approximation (GGA) with Hubbard (U) correction and spinorbit coupling (SOC). The GGAU implementation lead us to describe correctly the relativistic effect on 4f electrons for CeO 2. We clarify that the inclusion of the Hubbard U parameter and the spinorbit coupling are responsible for the ferromagnetic insulating of PrO 2 and TbO 2. The magnetic description is achieved by the spin-density contours and magnetic moment calculations, where we show the polarization of oxygen atoms from the rare earth atoms. The mechanical stability is shown via the elastic constants calculations. The optical properties, namely the dielectric function and the reflectivity are calculated for radiation up to 12 eV, giving interesting optoelectronic properties to these dioxides. © 2011 Elsevier B.V. All rights reserved.

  3. Radical-induced dephosphorylation of fructose phosphates in aqueous solution

    International Nuclear Information System (INIS)

    Zegota, H.; Sonntag, C. von

    1981-01-01

    Oxygen free N 2 O-saturated aqueous solutions of D-fructose-1-phosphate and D-fructose-6-phosphate were γ-irradiated. Inorganic phosphate and phosphate free sugars (containing four to six carbon atoms) were identified and their G-values measured. D-Fructose-1-phosphate yields (G-values in parentheses) inorganic phosphate (1.6), hexos-2-ulose (0.12), 6-deoxy-2,5-hexodiulose (0.16), tetrulose (0.05) and 3-deoxytetrulose (0.15). D-Fructose-6-phosphate yields inorganic phosphate (1.7), hexos-5-ulose (0.1), 6-deoxy-2,5-hexodiulose (0.36), 3-deoxy-2,5-hexodiulose and 2-deoxyhexos-5-ulose (together 0.18). On treatment with alkaline phosphatase further deoxy sugars were recognized and in fructose-1-phosphate G(6-deoxy-2,5-hexodiulose) was increased to a G-value of 0.4. Dephosphorylation is considered to occur mainly after OH attack at C-5 and C-1 in fructose-1-phosphate and at C-5 and C-6 in fructose-6-phosphate. Reaction mechanisms are discussed. (orig.)

  4. Synthesis of condensed double cesium manganese phosphates in melts of polyphosphoric acids

    International Nuclear Information System (INIS)

    Guzeeva, L.S.; Tananaev, I.V.

    1988-01-01

    This work is a continuation of investigations to establish the composition and formation conditions of condensed double cesium manganese phosphates and obtain x-ray and other characteristics of the compounds isolated. We studied cross sections of Cs 2 O-MnO 2 -P 2 O 5 -H 2 O systems at 150-400 degree C and three initial P : Mn ratios - 5, 7.5, and 10 - and at a constant P : Mn ratio of 15. The reaction of manganese and cesium oxides with melts of polyphosphoric acids at 150-400 degree C leads to the separation of three types of trivalent manganese and cesium condensed double phosphates - Cs 2 MnH 3 (P 2 O 7 ) 2 , triphosphate CsMnHP 3 O 10 , and cyclohexaphosphate Cs 3 Mn 3 -(P 6 O 18 ) 2 - in addition to a divalent manganese double cyclotriphosphate CsMnP 3 O 9 . The compounds separated were characterized by chemical, x-ray phase analysis, IR spectroscopic, and thermogravimetric methods

  5. Synthesis, Characterization and Comparative Luminescence Studies of Rare-Earth-Doped Gd2O3 Nanoparticles

    Science.gov (United States)

    Pyngrope, D.; Singh, L. R.; Prasad, A. I.; Bora, A.

    2018-04-01

    A facile direct precipitation method was used for the synthesis of luminescence nanomaterial. Gd2O3 doped with rare earth element Eu3+ is synthesized by polyol route. The synthesized nanoparticles show their characteristic red emission. The nanoparticles are characterized by x-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and photoluminescence (PL) study. The synthesized nanoparticles are spherical particles with 30 nm size. The photoluminescence studies show the characteristic Eu3+ red emission. The PL study shows the intensity of the magnetic dipole transition ( 5 D0 \\to 7 F1 ) at 592 nm compared to that of the electronic dipole transition ( 5 D0 \\to 7 F2 ) at 615 nm. The nanomaterials can show significant application in various display devices and biomedical applications for tracking.

  6. Electronic structures and Eu{sup 3+} photoluminescence behaviors in Y{sub 2}Si{sub 2}O{sub 7} and La{sub 2}Si{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhiya, E-mail: zhangzhiya@lzu.edu.cn [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000 (China); Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou, 730000 (China); Wang Yuhua [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000 (China); Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou, 730000 (China); Zhang Feng [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000 (China); Cao Haining [Computational Science Center, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of)

    2011-04-14

    Research highlights: > Host excitation near the band gap of Y{sub 2}Si{sub 2}O{sub 7} and La{sub 2}Si{sub 2}O{sub 7} is analyzed. > The calculated result well explains Eu{sup 3+} PL behaviors in Y{sub 2}Si{sub 2}O{sub 7} and La{sub 2}Si{sub 2}O{sub 7}. > The electronic structure and Eu{sup 3+} VUV PL in La{sub 2}Si{sub 2}O{sub 7} are first estimated. - Abstract: The electronic structures and linear optical properties of Y{sub 2}Si{sub 2}O{sub 7} (YSO) and La{sub 2}Si{sub 2}O{sub 7} (LSO) are calculated by LDA method based on the theory of DFT. Both YSO and LSO are direct-gap materials with the direct band gap of 5.89 and 6.06 eV, respectively. The calculated total and partial density of states indicate that in both YSO and LSO the valence band (VB) is mainly constructed from O 2p and the conduction band (CB) is mostly formed from Y 4d or La 5d. Both the calculated VB and CB of YSO exhibit relatively wider dispersion than that of LSO. In addition, the CB of YSO presents more electronic states. Meanwhile, the VB of LSO shows narrower energy distribution with higher electronic states density. The theoretical absorption of YSO shows larger bandwidth and higher intensity than that of LSO. The results are compared with the experimental host excitations and impurity photoluminescence in Eu{sup 3+}-doped YSO and LSO.

  7. Comparison of the Supercooled Spin Liquid States in the Pyrochlore Magnets Dy2Ti2O7 and Ho2Ti2O7

    Science.gov (United States)

    Eyal, Anna; Eyvazov, Azar B.; Dusad, Ritika; Munsie, Timothy J. S.; Luke, Graeme M.; Davis, J. C. Séamus

    Despite a well-ordered crystal structure and strong magnetic interactions between the Dy or Ho ions, no long-range magnetic order has been detected in the pyrochlore titanates Ho2Ti2O7 and Dy2Ti2O7. The low temperature state in these materials is governed by spin-ice rules. These constrain the Ising like spins in the materials, yet does not result in a global broken symmetry state. To explore the actual magnetic phases, we simultaneously measure the time- and frequency-dependent magnetization dynamics of Dy2Ti2O7 and Ho2Ti2O7 using toroidal, boundary-free magnetization transport techniques. We demonstrate a distinctive behavior of the magnetic susceptibility of both compounds, that is indistinguishable in form from the permittivity of supercooled dipolar liquids. Moreover, we show that the microscopic magnetic relaxation times for both materials increase along a super-Arrhenius trajectory also characteristic of supercooled glass-forming liquids. Both materials therefore exhibit characteristics of a supercooled spin liquid. Strongly-correlated dynamics of loops of spins is suggested as a possible mechanism which could account for these findings. Potential connections to many-body spin localization will also be discussed.

  8. Rare-earth elements and uranium in phosphatic nodules from the continental margins of India

    Digital Repository Service at National Institute of Oceanography (India)

    Nath, B.N.; Rao, B.R.; Rao, K.M.; Rao, Ch.M.

    of Pleistocene age. They are less than 1-5 cm in size, have carbonate flourapatite (CFA) as a single authigenic mineral phase, are free of detrital inclusions, and have very high P sub(2) O sub(5) contents (> 30%). In addition, soft and hard phosphatic nodules...

  9. In Situ Laser Coating of Calcium Phosphate on TC4 Surface for Enhancing Bioactivity

    Institute of Scientific and Technical Information of China (English)

    DENG Chi; WANG Yong; ZHANG Ya-ping; GAO Jia-cheng

    2007-01-01

    Titanium alloy has been a successful implant material owing to its excellent ratio of strength to weight,toughness, and bio-inert oxide surface. Significant progress has been made in improving the bioactivity of titanium alloy by coating its oxide surface with calcium phosphates. In the present study, in situ coating was reported on Ti6Al4V(TC4) surface with calcium phosphate (Ca-P) bioceramics synthesized and synchronously cladded by laser beam. This coating was grown by first preplacing directly the raw powders, which contain 80% of CaHPO4 ·2H2O, 20% of CaCO3, and dram of rare earth (RE), on the TC4 surfaces, and then exposing the surfaces to the laser beam with a power density of 12. 73-15.27 MW · m-2 and a scanning velocity of 10. 5 m/s. The resultant coating was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis and Different-thermal Scanning (TG-DSC), and Energy Dispersive X-ray Detection (EDX). The results show that these laser ceramics include hydroxyapatite (HA), tricalcium phosphate (TCP), Ca2P2O7, and other Ca-P phases, and the interface between the coating and the TC4 substrate has tighter fixation, in which the chemical bonding is approved. These laser hybrid coatings are useful in enhancing the bioactivity of titanium alloy surfaces.

  10. Current transport and electronic states in a,b-axis-oriented YBa2Cu3O7/PrBa2Cu3O7/YBa2Cu3O7 sandwich-type junctions

    International Nuclear Information System (INIS)

    Yoshida, J.; Nagano, T.; Hashimoto, T.

    1996-01-01

    Precise measurement of the temperature and voltage dependence of junction conductance has been carried out for a,b-axis-oriented YBa 2 Cu 3 O 7 /PrBa 2 Cu 3 O 7 /YBa 2 Cu 3 O 7 sandwich-type junctions to investigate the possible origin of Josephson coupling in these junctions. Regardless of the presence or absence of the Josephson effect, most of the junctions exhibited a dip in conductance around zero voltage in their dI/dV profiles at low temperatures. This dI/dV anomaly was attributed to the existence of a minimum in the density of states due to electron-electron interaction in disordered metals in the vicinity of a tunneling barrier within the junctions. The complex temperature dependence of junction conductance was reproduced well by a theoretical model in which both tunneling conduction paths and variable range hopping paths were assumed to exist within the PrBa 2 Cu 3 O 7 barrier layer. No definite evidence of current transport through a small number of localized levels or a metallic conduction path in PrBa 2 Cu 3 O 7 has been confirmed, even for junctions with a 20-nm-thick barrier layer. copyright 1996 The American Physical Society

  11. U.S. phosphate industry as a source of U3O8 to the year 2000

    International Nuclear Information System (INIS)

    Borg, I.Y.

    1976-01-01

    U 3 O 8 recovered as a by-product of the phosphate fertilizer industry may equal 3600-5200 tons by 1985 and represent 7-10 percent of the anticipated annual U.S. demand. If the enormous U.S. phosphate reserves and resources are mined primarily for their uranium content they appear sufficient to fill more than twice the projected cumulative U.S. demand to the year 2000

  12. In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} heterostructured nanoparticles with enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Yonglei [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic and Information Engineering, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Que, Wenxiu, E-mail: wxque@mail.xjtu.edu.cn [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic and Information Engineering, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Yin, Xingtian; He, Zuoli; Liu, Xiaobin; Yang, Yawei; Shao, Jinyou [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic and Information Engineering, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Kong, Ling Bing, E-mail: ELBKong@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore)

    2016-11-30

    Highlights: • Visible-light photocatalytic activities of the nanostructured In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} heterostructures were studied. • Effect of In{sub 2}O{sub 3} content on the photocatalytic activity of the In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} heterostructure was evaluated. • 0.1In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} heterostructure photocatalyst shows a superior photocatalytic activity. • Based on Mott-Schottky analysis and active species detection, a mechanism for the separation of photogenerated carriers is proposed. • The effective separation process of the photogenerated electron-hole pairs was testified by photocurrent test. - Abstract: In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} composite photocatalysts with various contents of cubic In{sub 2}O{sub 3} nanoparticles were fabricated by using impregnation method. A thriving modification of Bi{sub 2}Sn{sub 2}O{sub 7} by an introduction of In{sub 2}O{sub 3} was confirmed by using X-ray diffraction, UV–vis diffuse reflectance spectrometry, transmission electron microscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The samples composed of hybrids of In{sub 2}O{sub 3} and Bi{sub 2}Sn{sub 2}O{sub 7} exhibited a much higher photocatalytic activity for the degradation of Rhodamine B under visible light, as compared with pure In{sub 2}O{sub 3} and Bi{sub 2}Sn{sub 2}O{sub 7} nanoparticles. Optimized composition of the composite photocatalysts was 0.1In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7}, which shows a rate constant higher than those of pure In{sub 2}O{sub 3} and Bi{sub 2}Sn{sub 2}O{sub 7} by 4.06 and 3.21 times, respectively. Based on Mott-Schottky analysis and active species detection, the photoexcited electrons in the conduction band of In{sub 2}O{sub 3} and the holes in the valence band of Bi{sub 2}Sn{sub 2}O{sub 7} participated in reduction and oxidation reactions, respectively. Hence, ·OH, ·O{sub 2}{sup −} and h

  13. Redetermination of clinobaryl-ite, BaBe(2)Si(2)O(7).

    Science.gov (United States)

    Domizio, Adrien J Di; Downs, Robert T; Yang, Hexiong

    2012-10-01

    Clinobaryl-ite, ideally BaBe(2)Si(2)O(7) (chemical name barium diberyllium disilicate), is a sorosilicate mineral and dimorphic with baryl-ite. It belongs to a group of compounds characterized by the general formula BaM(2+) (2)Si(2)O(7), with M(2+) = Be, Mg, Fe, Mn, Zn, Co, or Cu, among which the Be-, Fe-, and Cu-members have been found in nature. The crystal structure of clinobaryl-ite has been re-examined in this study based on single-crystal X-ray diffraction data collected from a natural sample from the type locality (Khibiny Massif, Kola Peninsula, Russia). The structure of clinobaryl-ite can be considered as a framework of BeO(4) and SiO(4) tetra-hedra, with one of the O atoms coordinated to two Be and one Si, one coordinated to two Si, and two O atoms coordinated to one Si and one Be atom. The BeO(4) tetra-hedra share corners, forming chains parallel to the c axis, which are inter-linked by the Si(2)O(7) units oriented parallel to the a axis. The Ba(2+) cations (site symmetry m..) are in the framework channels and are coordinated by eleven O atoms in form of an irregular polyhedron. The Si-O(br) (bridging O atom, at site symmetry m..) bond length, the Si-O(nbr) (non-bridging O atoms) bond lengths, and the Si-O-Si angle within the Si(2)O(7) unit are in marked contrast to the corresponding values determined in the previous study [Krivovichev et al. (2004 ▶). N. Jb. Miner. Mh. pp. 373-384].

  14. Yb-doped phosphate double-cladding optical fiber for high-power laser applications

    Science.gov (United States)

    Mura, E.; Scarpignato, G. C.; Lousteau, J.; Boetti, N. G.; Abrate, S.; Milanese, D.

    2013-02-01

    A Yb-doped phosphate glass double cladding optical fiber was prepared using a custom designed glass composition (P2O5 - Al2O3 - Li2O - B2O3 - BaO - PbO - La2O3) for high-power amplifier and laser applications. The preform drawing method was followed, with the preform being fabricated using the rotational casting technique. This technique, previously developed for tellurite, fluoride or chalcogenide glass preforms is reported for the first time using rare earth doped phosphate glasses. The main challenge was to design an adequate numerical aperture between first and second cladding while maintaining similar thermo-mechanical properties in view of the fiber drawing process. The preform used for the fiber drawing was produced by rod-in-tube technique at a rotation speed of 3000 rpm. The rotational casting technique allowed the manufacturing of an optical fiber featuring high quality interfaces between core and internal cladding and between the internal and external cladding, respectively. Loss attenuation was measured using the cut-back method and lasing was demonstrated at 1022 nm by core pumping with a fiber pigtailed laser diode at the wavelength of 976 nm.

  15. Electronic parameters of Sr2M2O7 (M = V, Nb, Ta) and Sr-O chemical bonding

    DEFF Research Database (Denmark)

    Atuchin, Victor V.; Grivel, Jean-Claude; Zhang, Zhaoming

    2010-01-01

    XPS measurements were carried out on Sr2Nb2O7 and Sr2Ta2O7 powder samples, which were synthesized using standard solid state method. The binding energy differences between the O 1s and cation core level, Δ(O-Sr) = BE(O 1s) - BE(Sr 3d5/2), was used to characterize the valence electron transfer...... on the formation of the Sr-O bonds. The chemical bonding effects were considered on the basis of our XPS results for Sr2Nb2O7 and Sr2Ta2O7 and the previously published structural and XPS data for other Sr-oxide compounds. A new empirical relationship between Δ(O-Sr) and L(Sr-O) was obtained. Possible applications...

  16. Superconductivity in alkaline earth-substituted La2CuO/sub 4-y/

    International Nuclear Information System (INIS)

    Bednorz, J.G.; Mueller, K.A.; Takashige, M.

    1987-01-01

    La 2 CuO/sub 4-y/ ceramics containing a few percent of Ca 2+ , Sr 2+ , and Ba 2+ ions have been prepared. Resistivity and susceptibility measurements exhibit superconductive onsets (as in earlier Ba 2+ -containing samples). The onset temperature La 2 CuO/sub 4-y/ with Sr 2+ is higher and its superconductivity-induced diamagnetism larger than that found with Ba 2+ and Ca 2+ . This is proof that the electronic change resulting from alkaline earth-doping, rather than the size effect, is responsible for superconductivity. The ionic radius of Sr 2+ is close to that of La 3+ for which it presumably substitutes

  17. Mechanical Properties of Layered La2Zr2O7 Thermal Barrier Coatings

    Science.gov (United States)

    Guo, Xingye; Li, Li; Park, Hyeon-Myeong; Knapp, James; Jung, Yeon-Gil; Zhang, Jing

    2018-04-01

    Lanthanum zirconate (La2Zr2O7) has been proposed as a promising thermal barrier coating (TBC) material due to its low thermal conductivity and high stability at high temperatures. In this work, both single and double-ceramic-layer (DCL) TBC systems of La2Zr2O7 and 8 wt.% yttria-stabilized zirconia (8YSZ) were prepared using air plasma spray (APS) technique. The thermomechanical properties and microstructure were investigated. Thermal gradient mechanical fatigue (TGMF) tests were applied to investigate the thermal cycling performance. The results showed that DCL La2Zr2O7 + 8YSZ TBC samples lasted fewer cycles compared with single-layered 8YSZ TBC samples in TGMF tests. This is because DCL La2Zr2O7 TBC samples had higher residual stress during the thermal cycling process, and their fracture toughness was lower than that of 8YSZ. Bond strength test results showed that 8YSZ TBC samples had higher bond strength compared with La2Zr2O7. The erosion rate of La2Zr2O7 TBC samples was higher than that of 8YSZ samples, due to the lower critical erodent velocity and fracture toughness of La2Zr2O7. DCL porous 8YSZ + La2Zr2O7 had a lower erosion rate than other SCL and DCL La2Zr2O7 coatings, suggesting that porous 8YSZ serves as a stress-relief buffer layer.

  18. Ising versus XY anisotropy in frustrated R(2)Ti(2)O(7) compounds as "Seen" by Polarized Neutrons.

    Science.gov (United States)

    Cao, H; Gukasov, A; Mirebeau, I; Bonville, P; Decorse, C; Dhalenne, G

    2009-07-31

    We studied the field induced magnetic order in R(2)Ti(2)O(7) pyrochlore compounds with either uniaxial (R=Ho, Tb) or planar (R=Er, Yb) anisotropy, by polarized neutron diffraction. The determination of the local susceptibility tensor {chi(parallel to),chi(perpendicular)} provides a universal description of the field induced structures in the paramagnetic phase (2-270 K), whatever the field value (1-7 T) and direction. Comparison of the thermal variations of chi(parallel to) and chi(perpendicular) with calculations using the rare earth crystal field shows that exchange and dipolar interactions must be taken into account. We determine the molecular field tensor in each case and show that it can be strongly anisotropic.

  19. Physical and chemical characterization of pastes of bone cements with ZrO{sub 2}; Caracterizacion fisica y quimica de pastas de cementos oseos con ZrO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Quinto H, A. [Instituto Tecnologico de Zacatepec, A.P. 45, 62900 Zacatepec, Morelos (Mexico); Pina B, M.C. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, A.P. 70-360, 04510 Mexico D.F. (Mexico)

    2003-07-01

    Setting times and temperature of sixteen calcium phosphate cements added with ZrO{sub 2} were evaluated. Their behaviors were analysed to be used like injectable formulations in surgery of bone. Two cements of calcium phosphates enriched with ZrO{sub 2} with the best characteristics in setting times and temperature, were mechanically tested after 1 and 7 days of prepared. Density was determined using a pycnometer, chemical composition was determined by X-ray diffraction and the molecular structure was determined by infrared spectroscopy. (Author)

  20. Studies on the Ln/sub 2/O/sub 3/ (Ln: rare-earth elements)-SrO-V/sub 2/O/sub 3/ system, 1. Phase diagrams at 1400/sup 0/C

    Energy Technology Data Exchange (ETDEWEB)

    Shin-ike, T [Osaka Dental Coll., Hirakata (Japan); Adachi, G; Shiokawa, J

    1980-11-01

    Rare-earth oxides Ln/sub 2/O/sub 3/ (Ln : Nd, Eu or Er), strontium oxide SrO and vanadium oxide V/sub 2/O/sub 3/ were mixed in a given molecular ratio, heated at 1400/sup 0/C in vacuum. The products were examined by an x-ray diffraction method to study the phase relations of the ternary systems. On heating, part of the trivalent vanadium was oxidized to the tetravalent state by atmospheric oxygen. In this experimental condition, the following ternary-phase solid solutions were identified: perovskite type Nd sub(1-x)Sr sub(x)VO sub(3-0.1x) (x > 0.3. cubic, x < 0.3: orthorhombic) and Eu sub(1-x)Sr sub(x)VO sub(3-0.1x) (x > 0.4: cubic, x < 0.4: orthorhombic), K/sub 2/NiF/sub 4/ type SrO.Nd sub(1-x)Sr sub(x)VO sub(3-0.1x) (x > 0.3) and SrO.Eu sub(1-x)Sr sub(x)VO sub(3-0.1x) (x > 0.4) and Eu/sub 3/Ti/sub 2/O/sub 7/ type SrO.2Nd sub(1-x)Sr sub(x)VO sub(3-0.1x) (x > 0.3) and SrO.2Eu sub(1-x)Sr sub(x)VO sub(3-0.1x) (x > 0.4). For the Er/sub 2/O/sub 3/-SrO-V/sub 2/O/sub 3/ system, only a mixture of Er/sub 2/O/sub 3/, SrVO sub(2.9), ErVO/sub 3/, SrO and V/sub 2/O/sub 3/ was obtained.

  1. Rare earth activated NaY (MoO4)2 phosphors for NIR emission

    Science.gov (United States)

    Tawalare, P. K.; Bhatkar, V. B.; Talewar, R. A.; Joshi, C. P.; Moharil, S. V.

    2018-05-01

    Efficient NIR emission is reported for NaY(MoO4)2 activated with Nd3+ or Yb3+. Characteristic emission of rare earth ions is sensitized by MoO4-2 group. The excitation is in the near UV region of 350-400 nm. These phosphors could be useful for modifying the solar spectrum so as to match with the spectral response of c-Si solar cells.

  2. Effect of the addition of Na2O on the thermal properties and chemical durability of glasses of iron and uranium phosphates

    International Nuclear Information System (INIS)

    Arboleda Zuluaga, P.A; Rodriguez, D.S; Gonzalez Oliver, C; Rincon Lopez, J.M; Soldera, F

    2012-01-01

    A series of glass compositions including (54,6-73,5P 2 O 5 .14-22Fe 2 O 3.x Na 2 O.2,8-4,25 UO 2 ) %mol. x=0-28,4 were studied in function of sodium oxide content for the thermal properties and chemical durability. By means differential dilatometer measurements was possible establish the variation of Tg, and α Tsoft and analysis of the kinetics of sintering by means of High Temperature Microscopy (MAT) and dilatometric data of pressed pellets. The presence of modifier oxides in the structure of iron phosphate glasses causes slightly onset sintering anticipation in almost 25 o C The chemical durability was estimated performing the named Product Consistency Test (PCT-B) focused on determining the resistance of glasses for nuclear wastes. These glasses exhibit good chemical durability but it is significant impaired by the addition of x≥6wt%Na 2 O. It is aimed to achieve more stable compositions and get glass matrixes able to contain more uranium oxides allowing evaluating the potential application of these iron phosphate glasses for special, industrial and nuclear waste immobilization

  3. Hanford phosphate precipitation filtration process evaluation

    International Nuclear Information System (INIS)

    Walker, B.W.; McCabe, D.J.

    1997-01-01

    The purpose of this filter study was to evaluate cross-flow filtration as effective solid-liquid separation technology for treating Hanford wastes, outline operating conditions for equipment, examine the expected filter flow rates, and determine proper cleaning. A proposed Hanford waste pre-treatment process uses sodium hydroxide at high temperature to remove aluminum from sludge. This process also dissolves phosphates. Upon cooling to 40 degrees centigrade the phosphates form a Na7(PO4)2F9H2O precipitate which must be removed prior to further treatment. Filter studies were conducted with a phosphate slurry simulant to evaluate whether 0.5 micron cross-flow sintered metal Mott filters can separate the phosphate precipitate from the wash solutions. The simulant was recirculated through the filters at room temperature and filtration performance data was collected

  4. Characterization of radiative properties of Nd{sub 2}O{sub 3} doped phosphate and silicate glasses for solid state laser

    Energy Technology Data Exchange (ETDEWEB)

    Nandi, P., E-mail: pnandi@barc.gov.in; Shukla, R., E-mail: pnandi@barc.gov.in; Goswami, M., E-mail: pnandi@barc.gov.in [Glass and Advanced Materials Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Sudarsan, V. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085 (India)

    2014-04-24

    Nd{sub 2}O{sub 3} doped calcium aluminium phosphate and calcium aluminium silicate glasses prepared to compare their absorption and emission properties. Radiative lifetime of the excited state {sup 4}F{sub 3/2} derived by Judd-Ofelt theory applied to the absorption spectra. Using the photoluminescence spectrometer the steady state emission and relaxation time from excited energy level recorded under green light excitation. Phosphate glass has higher emission cross-section, higher radiative lifetime but less quantum efficiency due to non-radiative quenching through hydroxyl ions compared to silicate glass for Nd{sup 3+}:{sup 4}F{sub 3/2}→{sup 4}I{sub 9/2} emission.

  5. Complexation of neptunium(V) by salicylate, phthalate and citrate ligands in a pH 7.5 phosphate buffered system

    International Nuclear Information System (INIS)

    Rees, T.F.; Daniel, S.R.

    1984-01-01

    Conditional stability constants, enthalpies and entropies of complexation at pH 7.5 and ionic strength 0.1 have been determined for neptunium(V) complexes of phosphate, salicylate, phthalate and citrate. Results are given and discussed. At pH 7.5 salicylate does not form a complex with neptunium(V) due to the low charge density of the NpO 2 + ion and incomplete ionization of the salicylate ion. In all cases, only 1:1 complexes were identified. (U.K.)

  6. Hot corrosion behavior of YSZ, Gd2Zr2O7 and YSZ/Gd2Zr2O7 thermal barrier coatings exposed to molten sulfate and vanadate salt

    Science.gov (United States)

    Ozgurluk, Yasin; Doleker, Kadir Mert; Karaoglanli, Abdullah Cahit

    2018-04-01

    Thermal barrier coatings (TBCs) are mostly used in critical components of aircraft gas turbine engines. Hot corrosion is among the main deteriorating factors in TBCs which results from the effect of molten salt on the coating-gas interface. This type of corrosion is observed as a result of contamination accumulated during combustion processes. Fuels used in aviation industry generally contain impurities such as vanadium oxide (V2O5) and sodium sulfate (Na2SO4). These impurities damage turbines' inlet at elevated temperatures because of chemical reaction. Yttria stabilized zirconia (YSZ) is a conventional top coating material for TBCs while Gd2Zr2O7 is a new promising top coating material for TBCs. In this study, CoNiCrAlY metallic bond coat was deposited on Inconel 718 nickel based superalloy substrate material with a thickness about 100 μm using cold gas dynamic spray (CGDS) method. Production of TBCs were done with deposition of YSZ, Gd2Zr2O7, YSZ/Gd2Zr2O7 ceramic top coating materials using EB-PVD method, having a total thickness of 300 μm. Hot corrosion behavior of YSZ, Gd2Zr2O7, YSZ/Gd2Zr2O7 TBC systems were exposed to 45 wt.% Na2SO4 and 55 wt.% V2O5 molten salt mixtures at 1000 °C temperature. TBC samples were investigated and compared using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) analysis and X-ray diffractometer (XRD). The hot corrosion failure mechanisms of YSZ, Gd2Zr2O7 and YSZ/Gd2Zr2O7 TBCs in the molten salts were evaluated.

  7. Magnetic interactions in rhenium-containing rare earth double perovskites Sr{sub 2}LnReO{sub 6} (Ln=rare earths)

    Energy Technology Data Exchange (ETDEWEB)

    Nishiyama, Atsuhide; Doi, Yoshihiro; Hinatsu, Yukio, E-mail: hinatsu@sci.hokudai.ac.jp

    2017-04-15

    The perovskite-type compounds containing both rare earth and rhenium Sr{sub 2}LnReO{sub 6} (Ln=Y, Tb-Lu) have been prepared. Powder X-ray diffraction measurements and Rietveld analysis show that Ln{sup 3+} and Re{sup 5+} ions are structurally ordered at the B site of the perovskite SrBO{sub 3}. Magnetic anomalies are found in their magnetic susceptibility and specific heat measurements at 2.6–20 K for Ln=Y, Tb, Dy, Yb, Lu compounds. They are due to magnetic interactions between Re{sup 5+} ions. The results of the magnetic hysteresis and remnant magnetization measurements for Sr{sub 2}YReO{sub 6} and Sr{sub 2}LuReO{sub 6} indicate that the antiferromagnetic interactions between Re{sup 5+} ions below transition temperatures have a weak ferromagnetic component. The analysis of the magnetic specific heat data for Sr{sub 2}YbReO{sub 6} shows that both the Yb{sup 3+} and Re{sup 5+} ions magnetically order at 20 K. For the case of Sr{sub 2}DyReO{sub 6}, magnetic ordering of the Re{sup 5+} moments occurs at 93 K, and with decreasing temperature, the moments of Dy{sup 3+} ferromagnetically order at 5 K from the measurements of magnetic susceptibility and specific heat. - Graphical abstract: Crystal structure of double perovskite Sr{sub 2}LnReO{sub 6}. Red and black lines show cubic and monoclinic unit cells, respectively. - Highlights: • Double perovskites Sr{sub 2}LnReO{sub 6} (Ln=rare earths) were prepared. • They show an antiferromagnetic transition at 2.6–20 K. • In Sr{sub 2}DyReO{sub 6}, Dy and Re moments magnetically order at 5 and 93 K, respectively.

  8. Crystal structures and thermal decomposition of permanganates AE[MnO_4]_2 . n H_2O with the heavy alkaline earth elements (AE=Ca, Sr and Ba)

    International Nuclear Information System (INIS)

    Henning, Harald; Bauchert, Joerg M.; Conrad, Maurice; Schleid, Thomas

    2017-01-01

    Reexamination of the syntheses and crystal structures as well as studies of the thermal decomposition of the heavy alkaline earth metal permanganates Ca[MnO_4]_2 . 4 H_2O, Sr[MnO_4]_2 . 3 H_2O and Ba[MnO_4]_2 are the focus of this work. As an alternative to the very inelegant Muthmann method, established for the synthesis of Ba[MnO_4]_2 a long time ago, we employed a cation-exchange column loaded with Ba"2"+ cations and passed through an aqueous potassium-permanganate solution. We later used this alternative also with strontium- and calcium-loaded columns and all the compounds synthesized this way were indistinguishable from the products of the established methods. Ca[MnO_4]_2 . 4 H_2O exhibiting [CaO_8] polyhedra crystallizes in the orthorhombic space group Pccn with the lattice parameters a=1397.15(9), b=554.06(4) and c=1338.97(9) pm with Z=4, whereas Sr[MnO_4]_2 . 3 H_2O with [SrO_1_0] polyhedra adopts the cubic space group P2_13 with a=964.19(7) pm and Z=4. So the harder the AE"2"+ cation, the higher its demand for hydration in aqueous solution. Consequently, the crystal structure of Ba[MnO_4]_2 in the orthorhombic space group Fddd with a=742.36(5), b=1191.23(7) and c=1477.14(9) pm with Z=8 lacks any crystal water, but contains [BaO_1_2] polyhedra. During the thermal decomposition of Ca[MnO_4]_2 . 4 H_2O, the compound expels up to two water molecules of hydration, before the crystal structure collapses after the loss of the third H_2O molecule at 157 C. The crystal structure of Sr[MnO_4]_2 . 3 H_2O breaks down after the expulsion of the third water molecule as well, but this already occurs at 148 C. For both the calcium and the strontium permanganate samples, orthobixbyite-type α-Mn_2O_3 and the oxomanganates(III,IV) AEMn_3O_6 (AE=Ca and Sr) remain as final decomposition products at 800 C next to amorphous phases. On the other hand, the already anhydrous Ba[MnO_4]_2 thermally decomposes to hollandite-type BaMn_8O_1_6 and BaMnO_3 at 800 C.

  9. Decontamination of liquid radioactive waste by thorium phosphate

    International Nuclear Information System (INIS)

    Rousselle, J.; Grandjean, S.; Dacheux, N.; Genet, M.

    2004-01-01

    In the field of the complete reexamination of the chemistry of thorium phosphate and of the improvement of the homogeneity of Thorium Phosphate Diphosphate (TPD, Th 4 (PO 4 ) 4 P 2 O 7 ) prepared at high temperature, several crystallized compounds were prepared as initial powdered precursors. Due to the very low solubility products associated to these phases, their use in the field of the efficient decontamination of high-level radioactive liquid waste containing actinides (An) was carefully considered. Two main processes (called 'oxalate' and 'hydrothermal' chemical routes) were developed through a new concept combining the decontamination of liquid waste and the immobilization of the actinides in a ceramic matrix (TPD). In phosphoric media ('hydrothermal route'), the key-precursor was the Thorium Phosphate Hydrogen Phosphate hydrate (Th 2 (PO 4 ) 2 (HPO 4 ). H 2 O, TPHP, solubility product log(K S,0 0 ) ∼ - 67). The replacement of thorium by other tetravalent actinides (U, Np, Pu) in the structure, leading to the preparation of Th 2-x/2 An x/2 (PO 4 ) 2 (HPO 4 ). H 2 O solid solutions, was examined. A second method was also considered in parallel to illustrate this concept using the more well-known precipitation of oxalate as the initial decontamination step. For this method, the final transformation to single phase TPD containing actinides was purchased by heating a mixture of phosphate ions with the oxalate precipitate at high temperature. (authors)

  10. Synthesis and properties of scandium ortho-phosphate

    International Nuclear Information System (INIS)

    Eshchenko, L.S.; Pechkovskij, V.V.; Dvoskina, R.N.

    1979-01-01

    With the aim to elucidate the influence of synthesis conditions on the chemical composition and properties of orthophosphates of scandium, the interaction of orthophosphoric acid and scandium-containing component (oxide or salt) was studied under various conditions. In the interaction of scandium salt, phosphoric acid and ammonia at room temperature and pH 3.0; 5.0; 7.0 and 9.0 amorphous scandium phosphates have been obtained with the composition of x Sc 2 O 3 xY P 2 O 5 xz NH 3 xn H 2 O. After prolonged staying in mother liquor, roentgenoamorphous precipitates of phosphates transform into the crystalline state. The dependences are studied of the specific surface of amorphous phosphates on pH of precipitation and temperature of the heat treatment (200-800 deg C). Precipitates obtained in a neutral medium at 400 deg C temperature of thermal treatment, show a maximum specific surface. At a temperature of 820-840 deg C the crystallization of amorphous phase occurs followed by the recrystallization and formation of anhydrous SePO 4 of zircon type

  11. Physical and chemical characterization of pastes of bone cements with ZrO2

    International Nuclear Information System (INIS)

    Quinto H, A.; Pina B, M.C.

    2003-01-01

    Setting times and temperature of sixteen calcium phosphate cements added with ZrO 2 were evaluated. Their behaviors were analysed to be used like injectable formulations in surgery of bone. Two cements of calcium phosphates enriched with ZrO 2 with the best characteristics in setting times and temperature, were mechanically tested after 1 and 7 days of prepared. Density was determined using a pycnometer, chemical composition was determined by X-ray diffraction and the molecular structure was determined by infrared spectroscopy. (Author)

  12. High temperature phase transition of Tm2Ti2O7

    International Nuclear Information System (INIS)

    Shlyakhtina, A.V.; Shcherbakova, L.G.; Knot'ko, A.V.; Larina, L.L.; Borichev, S.A.

    2004-01-01

    A high temperature phase transition type order-disorder is investigated in Tm 2 Ti 2 O 7 at t>1600 Deg C. It is shown that this transformation is irreversible. Ion conductivity of synthesized at 1670 Deg C nanocrystalline Tm 2 Ti 2 O 7 constitutes 2x10 -3 S/cm at 740 Deg C and remains constant after heat treatment at 860 Deg C for 240 h in the air. It is revealed that the conductivity of specimens (grain size of 20-30 nm) on the basis of Tm 2 Ti 2 O 7 high temperature modification with a structure of disordered pyrochlore is independent of grain size [ru

  13. Effect of alkaline earth metal and magnesium cations on cadmium extraction from chloride solutions by tributyl phosphate

    International Nuclear Information System (INIS)

    Prokuev, V.A.; Belousov, E.A.

    1985-01-01

    At 298 K thermodynamic constants of cadmium (2) extraction from chloride solutions of magnesium, calcium, strontium and barium by tributyl phosphate are calculated. It is established, that logarithm of the thermodynamic extraction constant is in a linear dependence from the change in the cation hydration enthalpy in agqueous solution. It is shown, that activity coefficient of neutral complex CdVCl 2 differs from one, and it is the higher the more stable the complex is in alkaline earth metal chloride solutions

  14. Anisotropy of the irreversibility field for Zr-doped $(Y,Gd)Ba_2Cu_3O_{7-x}$ thin films up to 45T

    OpenAIRE

    Tarantini, C.; Jaroszynski, J.; Kametani, F.; Zuev, Y. L.; Gurevich, A.; Chen, Y.; Selvamanickam, V.; Larbalestier, D. C.; Christen, D. K.

    2012-01-01

    The anisotropic irreversibility field B$_{Irr}$ of two $YBa_2Cu_3O_{7-x}$ thin films doped with additional rare earth (RE)=(Gd,Y) and Zr and containing strong correlated pins (splayed BaZrO$_{3}$ nanorods, and $RE_2O_3$ nanoprecipitates), has been measured over a very broad range up to 45T at temperatures 56 K

  15. Decaying shock studies of phase transitions in MgO-SiO2 systems: implications for the Super-Earths' interiors

    Science.gov (United States)

    Bolis, R.; Morard, G.; Vinci, T.; Ravasio, A.; Bambrink, E.; Guarguaglini, M.; Koenig, M.; Musella, R.; Françoise, R.; Bouchet, J.; Ozaki, N.; Miyanishi, K.; Sekine, T.; Sakawa, Y.; Sano, T.; Kodama, R.; Guyot, F. J.; Benuzzi, A.

    2016-12-01

    Mantles of telluric exoplanets, so-called Earth-like and Super-Earths, are expected to be mainly composed of different type of oxides, such as periclase (MgO), enstatite (MgSiO3) and forsterite (Mg2SiO4). Determining the phase diagrams, melting curves and liquid properties of these compounds under extreme pressure (0.2-1 TPa) is crucial to model the internal dynamic of these exoplanets, as the melting of mantle components controls planetary temperature profiles [6]. Experimentally, these planetary thermodynamic states can be achieved with laser-shock compression. Here we present laser-driven decaying shock experiments on MgO, MgSiO3 and Mg2SiO4 samples performed at LULI and GEKKO laser facilities, where we focused 1.2-2.5 ns laser pulses with an intensity between 3-8 1013 W/cm2 exploring pressures between 0.2 and 1 TPa and temperature between 5000 and 30000 K. We determined the thermodynamic states using rear side optical diagnostics. We observed a single transition for MgO associated to melting (at 0.47 TPa ± 0.04 and 9863 ± 812 K) and no evidence of a liquid-liquid transition, dissociation or melting for all the other compounds in the range 150-500 Gpa and 200-800 Gpa respectively for MgSiO3 and Mg2SiO4. Some implications are presented comparing our data experimental and theoretical data found in literature [1, 2, 3, 4, 5]. In particular these results represent a key input to solve the controversy on a possible MgSiO3 liquid-liquid phase transition. Moreover we propose a revision of the phase diagram of MgO, with a lower melting line which results in a lower temperature profile for super-Earths. Finally our data evidence the presence of a poor electrically conducting liquid in the phase diagram of all the studied material, with implications for the modelling of magnetic field generation via dynamo mechanism.[1] McWilliams et al., Science 338 (2012): 1330-1333. [2] Spaulding et al., Physical Review Letters108 (2012): 065701. [3] Root et al., Physical Review

  16. Microstructures and mechanical properties of Gd{sub 2}Zr{sub 2}O{sub 7}/ZrO{sub 2}(3Y) ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Lei [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, Liaoning 110819 (China); Key Laboratory for Advanced Ceramics and Application of Shenyang, Shenyang University of Chemical Technology, Shenyang, Liaoning 110142 (China); Ma, Weimin, E-mail: maleisy2003@163.com [Key Laboratory for Advanced Ceramics and Application of Shenyang, Shenyang University of Chemical Technology, Shenyang, Liaoning 110142 (China); Sun, Xudong, E-mail: xdsun@mail.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, Liaoning 110819 (China); Ji, Lianyong; Liu, Jianan; Hang, Kai [Key Laboratory for Advanced Ceramics and Application of Shenyang, Shenyang University of Chemical Technology, Shenyang, Liaoning 110142 (China)

    2015-09-25

    Highlights: • Gd{sub 2}Zr{sub 2}O{sub 7}/ZrO{sub 2}(3Y) composites were prepared using vacuum sintering. • The phase composition and microstructure are studied. • Gd{sub 2}Zr{sub 2}O{sub 7}/ZrO{sub 2}(3Y) materials show superior mechanical properties. • The solid solution strengthening and stress-induced phase transformation toughening mechanism are proposed. • Two kinds of mechanisms explain the improvement of mechanical properties. - Abstract: Gd{sub 2}Zr{sub 2}O{sub 7}/ZrO{sub 2}(3Y) composite ceramics were prepared by vacuum sintering using Gd{sub 2}Zr{sub 2}O{sub 7} and ZrO{sub 2}(3Y) nanoparticles. The ceramics were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), the three-point-bending technique and single-edge-notched-beam tests. The effect of various proportions of ZrO{sub 2}(3Y) on the phase composition, microstructure, bending strength and fracture toughness of the final Gd{sub 2}Zr{sub 2}O{sub 7}/ZrO{sub 2}(3Y) composite ceramics was also analyzed. The change from m-ZrO{sub 2} to t-ZrO{sub 2} phase contents, before and after fracture, was measured using XRD quantitative phase analysis. The results confirm that, with the increasing content of ZrO{sub 2}(3Y), a phase transition from solid solution to saturated precipitation occurs and the bending strength and fracture toughness of the samples increase gradually. When the content of ZrO{sub 2}(3Y) reached 95 vol.%, the Gd{sub 2}Zr{sub 2}O{sub 7}/ZrO{sub 2}(3Y) composite ceramics had a bending strength of 547 MPa and a fracture toughness of 5.5 MPa m{sup 1/2}, indicating that stress-induced phase transformation toughening was an efficient way to increase the mechanical properties of the Gd{sub 2}Zr{sub 2}O{sub 7} ceramics.

  17. Unified mechanism of alkali and alkaline earth catalyzed gasification reactions of carbon by CO2 and H2O

    Science.gov (United States)

    Chen, S.G.; Yang, R.T.

    1997-01-01

    From molecular orbital calculations, a unified mechanism is proposed for the gasification reactions of graphite by CO2 and H2O, both uncatalyzed and catalyzed by alkali and alkaline earth catalysts. In this mechanism, there are two types of oxygen intermediates that are bonded to the active edge carbon atoms: an in-plane semiquinone type, Cf(O), and an off-plane oxygen bonded to two saturated carbon atoms that are adjacent to the semiquinone species, C(O)Cf(O). The rate-limiting step is the decomposition of these intermediates by breaking the C-C bonds that are connected to Cf(O). A new rate equation is derived for the uncatalyzed reactions, and that for the catalyzed reactions is readily available from the proposed mechanism. The proposed mechanism can account for several unresolved experimental observations: TPD and TK (transient kinetics) desorption results of the catalyzed systems, the similar activation energies for the uncatalyzed and catalyzed reactions, and the relative activities of the alkali and alkaline earth elements. The net charge of the edge carbon active site is substantially changed by gaining electron density from the alkali or alkaline earth element (by forming C-O-M, where M stands for metal). The relative catalytic activities of these elements can be correlated with their abilities of donating electrons and changing the net charge of the edge carbon atom. As shown previously (Chen, S. G.; Yang, R. T. J. Catal. 1993, 141, 102), only clusters of the alkali compounds are active. This derives from the ability of the clusters to dissociate CO2 and H2O to form O atoms and the mobility of the dissociated O atoms facilitated by the clusters.

  18. Thermodynamics of the hydrolysis reactions of α-D-galactose 1-phosphate, sn-glycerol 3-phosphate, 4-nitrophenyl phosphate, phosphocreatine, and 3-phospho-D-glycerate

    International Nuclear Information System (INIS)

    Goldberg, Robert N.; Lang, Brian E.; Lo, Catherine; Ross, David J.; Tewari, Yadu B.

    2009-01-01

    Microcalorimetry, high-performance liquid chromatography (h.p.l.c.), and an enzymatic assay have been used to conduct a thermodynamic investigation of five phosphate hydrolysis reactions: {α-D-galactose 1-phosphate(aq) + H 2 O(l) = D-galactose(aq) + orthophosphate(aq)} (1), {sn-glycerol 3-phosphate(aq) + H 2 O(l) = glycerol(aq) + orthophosphate(aq)} (2), {4-nitrophenyl phosphate(aq) + H 2 O(l) = 4-nitrophenol(aq) + orthophosphate(aq)} (3), {phosphocreatine(aq) + H 2 O(l) = creatine(aq) + orthophosphate(aq)} (4), and {3-phospho-D-glycerate(aq) + H 2 O(l) = D-glycerate(aq) + orthophosphate(aq)} (5). Calorimetrically determined enthalpies of reaction Δ r H(cal) were measured for reactions (1)-(5) and the apparent equilibrium constant K' was measured for reaction (2). The pKs and standard enthalpies of reaction Δ r H 0 for the H + and Mg 2+ binding reactions of the reactants and products in the aforementioned reactions were obtained either from the literature or by estimation. A chemical equilibrium model was then used to calculate standard equilibrium constants K and standard enthalpies of reaction Δ r H 0 for chemical reference reactions that correspond to the overall biochemical reactions that were studied experimentally. Property values from the literature and thermodynamic network calculations were used to obtain values of the equilibrium constants for the chemical reference reactions that correspond to the overall biochemical reactions (1). These values were compared with other results from the literature and also correlated with structural features. The results obtained in this study can be used in the chemical equilibrium model to calculate values of K', the standard apparent Gibbs free energy changes Δ r G '0 , the standard apparent enthalpy changes Δ r H '0 , changes in binding of the proton Δ r N(H + ), and the position of equilibrium for the overall biochemical reactions considered in this study over a reasonably wide range of temperature, pH, p

  19. Sm3+ and Eu3+ sorption in mixed phosphates of Zr

    International Nuclear Information System (INIS)

    Contreras R, A.

    2011-01-01

    The storage of high level radioactive waste in deep geological repositories is an issue of international research in countries with nuclear reactors. A major risk is the groundwater infiltration, which can cause degradation of the containers and leaching the radioactive waste through the different barriers. The study of materials for use as engineered barriers is fundamental, because if dissolution is present, the elements can be captured, ensuring that radioactive materials do not disperse off. The work is divided in four parts, the first describes the techniques developed for the synthesis of phosphates: NaZr 2 (PO 4 ) [NZP] and τ-Zr(Na 0.06 H 0.94 PO 4 ) 2 [TZP-Na], their chemical and morphological characterization, thermal stability and surface area. The obtained NZP shows a diffraction diagram similar to the Jcpds pattern, it has a surface area of 4.9±0.1 m 2 ·g -1 . There are not reports of diffraction patterns for TZP-Na, which has a surface area of 22.9±0.40 m 2 ·g -1 . The hydrogenphosphate obtained, τ-Zr(HPO 4 ) 2 , shows a diffraction diagram similar to that reported by Nor by. The second part presents the physicochemical characterization of the phosphates surface. The constants of formation of surface sites and their distribution were calculated using FITEQL 4.0. The sites surface density (d s ) were determined from potentiometric titration curves of phosphate, hydrogen phosphate and NaClO 4 0.5 M; d s were 3.2 sites nm -2 for NZP and 2.1 sites·nm -2 for TZP-Na. The values of curves formation constants for surface sites were, for NZP: K 1P-O =2, K 2P-O =-7, K 1Zr-O =6.11, K 1Zr-O =7.94, and for TZP-Na: K 1P-O =5.14, K 2P-O =-7.03, K 1Zr-O =2.60, K 1Zr-O =-9.85. The third part of the work reports the samarium and europium sorption curves on phosphate and on hydrogenphosphate at different ph values. The values of the curves were fed on FITEQL 4.0 program and NZP surface complexation constants were obtained. The results for the NZP show, for both

  20. Systems of OsO4-RuO4 and Re2O7-OsO4

    International Nuclear Information System (INIS)

    Nisel'son, L.A.; Sokolova, T.D.; Orlov, A.M.; Shorikov, Yu.S.

    1981-01-01

    The meltability diagrams of the systems OsO 4 -RuO 4 and Re 2 O 7 -OsO 4 are studied using the visual-polythermal method. The OsO 4 -RuO 4 system forms a continuous series of solid solutions with practically rectilinear line of the liquidus. The Re 2 O 7 -OsO 4 system of the eutectic type has the eutectics degenerated from the side of OsO 4 . For the system OsO 4 (basis)-RuO 4 (admixture) the equilibrium coefficient of distribution is determined using the method of directed crystallization [ru

  1. Magnetic tri-axial orientation in (Y1-xErx)2Ba4Cu7O15-y superconductors

    International Nuclear Information System (INIS)

    Horii, S.; Okuhira, S.; Yamaki, M.; Haruta, M.; Maeda, T.; Shimoyama, J.

    2011-01-01

    (Y 1-x Er x ) 2 Ba 4 Cu 7 O 15-y [(Y,Er)247] was synthesized for clarifying a magnetic role of Er ion. The three magnetization axes of (Y,Er)247 were obtained from tri-axial orientation using a modulated rotation magnetic field. Magnetic anisotropy of Er ion is roughly ten times higher than that for Y247 at room temperature. Importance of rare-earth ions was shown for reduction of required magnetic fields in the tri-axial magnetic orientation. We report the tri-axial grain-orientation effects under a modulated rotation magnetic field for (Y 1-x Er x ) 2 Ba 4 Cu 7 O y [(Y, Er)247]. The magnetic easy axis at room temperature was drastically changed around x ∼ 0.1; however, the Er-doping levels for the conversion of magnetic easy axes from the c-axis to the ab-direction and from the a- to b-axes were quite different. Tri-axial single-ion magnetic anisotropy of Er 3+ was roughly 10 times greater than tri-axial magnetic anisotropy generated by both the superconducting CuO 2 plane and the blocking Cu-O chain layer. An appropriate choice of rare-earth (RE) ions in RE-based cuprate superconductors enables the reduction of the required magnetic field for the production of bulks and thick films based on the magnetic orientation technique.

  2. Electronic structure of layered titanate Nd 2Ti 2O 7

    Science.gov (United States)

    Atuchin, V. V.; Gavrilova, T. A.; Grivel, J.-C.; Kesler, V. G.

    2008-10-01

    The electronic structure of the binary titanate Nd 2Ti 2O 7 has been studied by X-ray photoelectron spectroscopy (XPS). Spectral features of the valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Nd 2Ti 2O 7 are determined as αTi = 873.5 and αO = 1042.2 eV. Chemical bonding effects have been discussed with the binding energies differences ΔTi = (BE O 1s - BE Ti 2p 3/2) = 71.5 eV and ΔNd = (BE Nd 3d 5/2 - BE O 1s) = 452.5 eV as key parameters in comparison with those in other titanium- and neodymium-bearing oxides.

  3. Study of a Mixed Alkaline–Earth Effect on Some Properties of Glasses of the CaO-MgO-Al2O3-SiO2 System

    Directory of Open Access Journals (Sweden)

    Valle-Fuentes, J. F.

    2007-06-01

    Full Text Available In the present work, we studied a “Mixed Alkaline–Earth Effect”, i.e. the non-linear behaviour showed by the glass transition temperature as well as by the compressive strength of glasses of the CaO-MgO-Al2O3-SiO2 system, when a part of the CaO contained in them was substituted by a BaO/SrO mixture, in variable molar proportions. An important factor for the occurrence of this phenomenon was the difference in atomic weight, ionic radii and field strength of the Ba2+ and Sr2+ ions in comparison with those corresponding to the Ca2+ ion. Another factor considered was the likely occurrence of a microphase separation caused by the addition of BaO and/or SrO, together with the presence of F- and Mg2+ in the glasses. Other glass properties studied as a function of the CaO substitution level were density, glass molar volume, oxygen molar volume, packing fraction, and chemical resistance in neutral, basic and acidic aqueous media. In general, the structural reinforcement of the glass network caused by the partial substitution of CaO by a BaO/SrO mixture was accompanied by an improvement in the alkaline resistance of the materials, which were found to be suitable for applications in corrosive environments, especially in basic media. Keywords: Mixed alkaline–earth effect; CaO-MgO-Al2O3-SiO2 system; glass properties.En el presente trabajo, se estudia el comportamiento no lineal mostrado por la temperatura de transición vítrea y por la resistencia a la compresión de vidrios del sistema CaO-MgO-Al2O3-SiO2, cuando una parte del CaO contenido en los mismos es sustituido por una mezcla de BaO/SrO, en relación molar variable. Factores importantes para que se de este comportamiento son la diferencia entre pesos atómicos, radios iónicos e intensidad de campo de los iones Ba2+ y Sr2+ y los del propio ión Ca2+. Otro factor considerado ha sido la probable existencia de una separación de microfases originada por la adición de BaO y/o SrO, junto con la

  4. Core level photoemission spectroscopy and chemical bonding in Sr2Ta2O7

    DEFF Research Database (Denmark)

    Atuchin, V. V.; Grivel, Jean-Claude; Zhang, Z. M.

    2009-01-01

    Electronic parameters of constituent element core levels of strontium pyrotantalate (Sr2Ta2O7) were measured with X-ray photoelectron spectroscopy (XPS). The Sr2Ta2O7 powder sample was synthesized using standard solid state method. The valence electron transfer on the formation of the Sr-O and Ta......-O bonds was characterized by the binding energy differences between the O 1s and cation core levels, Delta(O-Sr) = BE(O 1s) - BE(Sr 3d(5/2)) and Delta(O-Ta) = BE(O 1s) - BE(Ta 4f(7/2)). The chemical bonding effects were considered on the basis of our XPS results for Sr2Ta2O7 and earlier published...

  5. Radioactivity of phosphate ores from Karatas-Mazidag phosphate deposit of Turkey

    International Nuclear Information System (INIS)

    Akyuez, T.; Varinlioglu, A.; Kose, A.; Akyuez, S.

    2000-01-01

    The specific activities of 238 U, 226 Ra, 232 Th and 40 K in the composite samples of phosphate ores of type I (grey-coloured ore, with high P 2 O 5 (21-35%) and low calcite content) and of type II (grey coloured calcite ore, with low P 2 O 5 content (5-17%)) of Karatas-Mazidag phosphate deposit, Turkey, have been determined by gamma spectrometry together with phosphatic animal feed ingredients. The concentrations of 238 U, 226 Ra, 232 Th and 40 K were found to be up to 557, 625, 26 and 297 Bq x kg -1 , respectively. Radium equivalent activities of samples were calculated and compared with those given in the literature. Uranium concentration of the individual phosphate samples, from which composite samples of ores of type I and II have been prepared, were found to show and increasing trend with increasing P 2 O 5 and F concentrations. (author)

  6. Hydrated aluminophosphate (AlPO/sub 4/. 1. 5H/sub 2/O) with PO/sub 4/, AlO/sub 4/ and AlO/sub 4/(H/sub 2/O)/sub 2/ groups and encapsulated water

    Energy Technology Data Exchange (ETDEWEB)

    Pluth, J.J.; Smith, J.V.

    1986-09-15

    Aluminium phosphate hydrate, AlPO/sub 4/ /sub ./ 1.5H/sub 2/O, M/sub r/=148.98, orthorhombic, Pbca, a=19.3525(13), b=9.7272(7), c=9.7621(8) A, V=1837.7(1) A/sup 3/, Z=16, D/sub x/=2.15 g cm/sup -3/, lambda(CuK..cap alpha..)=1.5418 A, ..mu..=68.2 cm/sup -1/, F(000)=1200, Tproportional to 295 K, R=0.033 for 1530 diffractions. A 4-connected framework contains PO/sub 4/ tetrahedra interposed between AlO/sub 4/ tetrahedra and AlO/sub 4/(H/sub 2/O)/sub 2/ octahedra at the nodes of cross-linked alternate 6/sup 3/ and 4.8/sup 2/ nets. A two-dimensional channel system, limited by 8-rings, lies between adjacent 6/sup 3/ nets. One H/sub 2/O of each octahedron lies in a 6-ring, and the other forms a continuous chain with a third H/sub 2/O which is held in place only by hydrogen bonds.

  7. 31P T2s of phosphomonoesters, phosphodiesters, and inorganic phosphate in the human brain at 7T

    Science.gov (United States)

    Klomp, Dennis W.J.; Wijnen, Jannie P.

    2017-01-01

    Purpose To determine the phosphorus‐31 T2s of phosphomonoesters, phosphodiesters, and inorganic phosphate in the healthy human brain at 7T. Methods A 3D chemical shift imaging multi‐echo sequence with composite block pulses for refocusing was used to measure one free induction decay (FID) and seven full echoes with an echo spacing of 45 ms on the brain of nine healthy volunteers (age range 22–45 years; average age 27 ± 8 years). Spectral fitting was used to determine the change in metabolic signal amplitude with echo time. Results The average apparent T2s with their standard deviation were 202 ± 6 ms, 129 ± 6 ms, 86 ± 2 ms, 214 ± 10 ms, and 213 ± 11 ms for phosphoethanolamine, phosphocholine, inorganic phosphate, glycerophosphoethanolamine, and glycerophosphocholine, respectively. Conclusion The determined apparent T2 for phosphoethanolamine, glycerophosphocholine, and glycerophosphoethanolamine is approximately 200 ms. The lower apparent T2 value for phosphocholine is attributed to the overlap of this resonance with the 3‐phosphorous resonance of 2,3‐diphosphoglycerate from blood, with an apparent shorter T2. Omitting the FID signal and the first echo of phosphocholine leads to a T2 of 182 ± 7 ms, whereas a biexponential analysis leads to 203 ± 4 ms. These values are more in line with phosphoethanolamine and the phosphodiesters. The short T2 of inorganic phosphate is subscribed to the fast reversible exchange with γ‐adenosine triphosphate, which is mediated by glyceraldehyde‐3‐phosphate dehydrogenase and phosphoglycerate kinase within the glycolytic pathway. Magn Reson Med 80:29–35, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any

  8. Electronic structure of layered titanate Nd2Ti2O7

    DEFF Research Database (Denmark)

    Atuchin, V.V.; Gavrilova, T.A.; Grivel, Jean-Claude

    2008-01-01

    The electronic structure of the binary titanate Nd2Ti2O7 has been studied by X-ray photoelectron spectroscopy (XPS). Spectral features of the valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Nd2Ti2O7 are determined as alpha...

  9. Phosphate Tether-Mediated Ring-Closing Metathesis for the Generation of P-Stereogenic, Z-Configured Bicyclo[7.3.1]- and Bicyclo[8.3.1]phosphates.

    Science.gov (United States)

    Markley, Jana L; Maitra, Soma; Hanson, Paul R

    2016-02-05

    A phosphate tether-mediated ring-closing metathesis (RCM) study to the synthesis of Z-configured, P-stereogenic bicyclo[7.3.1]- and bicyclo[8.3.1]phosphates is reported. Investigations suggest that C3-substitution, olefin substitution, and proximity of the forming olefin to the bridgehead carbon of the bicyclic affect the efficiency and stereochemical outcome of the RCM event. This study demonstrates the utility of phosphate tether-mediated desymmetrization of C2-symmetric, 1,3-anti-diol-containing dienes in the generation of macrocyclic phosphates with potential synthetic and biological utility.

  10. Intense 2.7 µm emission and structural origin in Er3+-doped bismuthate (Bi2O3-GeO2-Ga2O3-Na2O) glass.

    Science.gov (United States)

    Guo, Yanyan; Li, Ming; Hu, Lili; Zhang, Junjie

    2012-01-15

    The 2.7 μm emission properties in Er3+-doped bismuthate (Bi2O3-GeO2-Ga2O3-Na2O) glass were investigated in the present Letter. An intense 2.7 μm emission in Er3+-doped bismuthate glass was observed. It is found that Er3+-doped bismuthate glass possesses high spontaneous transition probability A (65.26 s(-1)) and large 2.7 μm emission cross section σ(em) (9.53×10(-21) cm2) corresponding to the stimulated emission of Er3+:4I11/2→4I13/2 transition. The emission characteristic and energy transfer process upon excitation of a conventional 980 nm laser diode in bismuthate glass were analyzed. Additionally, the structure of bismuthate glass was analyzed by the Raman spectrum. The advantageous spectroscopic characteristics of Er3+ single-doped bismuthate glass together with the prominent thermal property indicate that bismuthate glass might become an attractive host for developing solid-state lasers around 2.7 μm.

  11. Oxygen isotope effect in YBa2Cu3O7 prepared by burning YBa2Cu3 in 16O and 18O

    Science.gov (United States)

    Yvon, Pascal J.; Schwarz, R. B.; Pierce, C. B.; Bernardez, L.; Conners, A.; Meisenheimer, R.

    1989-04-01

    We prepared YBa2Cu3 powder by ball milling a 2:1 molar mixture of the intermetallics BaCu and CuY. We synthesized YBa2Cu3(16O)7-x and YBa2Cu3(18O)7-x by oxidizing the YBa2Cu3 powder in 16O and 18O. The 16O/18O ratios were determined by laser-ionization and sputtering-ionization mass spectroscopy. The YBa2Cu3(160)7-x sample had 99.8 at. %16O, and the YBa2Cu3(18O)7-x sample had 96.5 at. %18O. Susceptibility measurements of the superconducting transition temperature (Tc=91.7 K for 16O; half-point transition at 84 K show an isotope effect of 0.4+/-0.1 K.

  12. Rare-earths influence in the thermoluminescent response of monoclinic ZrO{sub 2}; Influencia de tierras raras en la respuesta termoluminiscente de ZrO{sub 2} monoclinico

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza A, D.; Gonzalez M, P.R. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Vasquez L, M.J.; Rubio R, E. [Centro Universitario de Vinculacion, BUAP, 72000 Puebla (Mexico)

    2005-07-01

    Zirconium oxide (ZrO{sub 2}) with rare-earths (Nd, Dy, Eu and Y) as dopant were prepared by sol gel method and irradiated with gamma radiation. The thermoluminescent (TL) signal was studied as function of the impurities present for temperatures from 50 to 350 C. Pure ZrO{sub 2} produces a strong TL signal induced by gamma radiation, with a maximum located at 150 C, while ZrO{sub 2} doped with Nd, Dy and Y showed a TL signal with minor intensity, but with a maximum like to pure ZrO{sub 2}. However, when Eu is present as impurity the TL signal is much smaller than pure ZrO{sub 2}, with a maximum very enlarged. These results indicate that exits a strong influence of the rare-earths presents in the TL response and opens the possibility to control the TL signal in a wide range of dosages allowing to use these systems as a wide range dosimeter. Details of the thermoluminescent behavior of pure and doped ZrO{sub 2} will be discussed. (Author)

  13. Faceting of (001) CeO2 Films: The Road to High Quality TFA-YBa2Cu3O7 Multilayers

    International Nuclear Information System (INIS)

    Coll, M; Gazquez, J; Sandiumenge, F; Pomar, A; Puig, T; Obradors, X; Espinos, J P; Gonzalez-Elipe, A R

    2006-01-01

    CeO 2 films are technologically important as a buffer layer for the integration of superconducting YBa 2 Cu 3 O 7 films on biaxially textured Ni substrates. The growth of YBa 2 Cu 3 O 7 layers on the CeO 2 cap layers by the trifluoroacetate (TFA) route remains a critical issue. To improve the accommodation of YBa 2 Cu 3 O 7 on CeO 2 , surface conditioning or CeO 2 is required. In this work we have applied ex-situ post-processes at different atmospheres to the CeO 2 layers deposited on YSZ single crystals using rf sputtering. XPS analysis showed that post-annealing CeO 2 layer in Ar/H 2 /H 2 O catalyses in an unexpected way the growth of (001)- terraces. We also report on the growth conditions of YBa 2 Cu 3 O 7 -TFA on CeO 2 buffered YSZ single crystal grown by chemical solution deposition and we compare them with those leading to optimized YBa 2 Cu 3 O 7 -TFA films on LaAlO 3 single crystals. Critical currents up to 1.6 MA/cm 2 at 77 K have been demonstrated in 300 nm thick YBa 2 Cu 3 O 7 layers on CeO 2 /YSZ system. The optimized processing conditions have then been applied to grow YBa 2 Cu 3 O 7 -TFA films on Ni substrates having vacuum deposited cap layers of CeO 2

  14. Electronic structure of PrBa2Cu3O7

    International Nuclear Information System (INIS)

    Singh, D.J.

    1994-01-01

    Electronic-structure calculations, within the local spin density approximation (LSDA), are reported for PrBa 2 Cu 3 O 7 . Significant charge transfer from the Pr ions to both the CuO 2 planes and the chains is found relative to YBa 2 Cu 3 O 7 . This supports hole depletion explanations for the insulating character of PrBa 2 Cu 3 O 7 . The LSDA electronic structure shows a prominent ''ridge'' Fermi surface analogous to that in YBa 2 Cu 3 O 7 , but broader. It is proposed that high-resolution positron measurements of this width may provide a useful test of hole depletion models

  15. Hot spot in GdBa2Cu3O7-δ-based composite ceramics rods and their applications for oxygen sensors

    International Nuclear Information System (INIS)

    Okamoto, T; Takata, M

    2011-01-01

    A hot spot, which is a local area glowing orange, appears in a LnBa 2 Cu 3 O 7-δ (Ln: rare earth element) ceramic rod when a voltage exceeding a certain value is applied to the rod at room temperature. After the appearance of the hot spot, the current changes according to the oxygen partial pressure in ambient atmosphere, which acts as an oxygen sensor without the need for any heating system. The GdBa 2 Cu 3 O 7-δ rod tended to be melted and broken by a sustained presence of the hot spot in a high oxygen partial pressure Po 2 (∼100 kPa). The composite rod containing high melting point materials, such as BaAl 2 O 4 , BaZrO 3 and Gd 2 BaCuO 5 , showed a remarkable high durability in O 2 atmosphere. In a low Po 2 ( 2 Cu3O 7-δ rod decreases to almost zero and the hot spot disappeared, resulting in an insensitive rod to oxygen. The composite rod containing CuO detected oxygen even in Po 2 < 0.002 kPa.

  16. Study of a hydraulic dicalcium phosphate dihydrate/calcium oxide-based cement for dental applications.

    Science.gov (United States)

    el-Briak, Hasna; Durand, Denis; Nurit, Josiane; Munier, Sylvie; Pauvert, Bernard; Boudeville, Phillipe

    2002-01-01

    By mixing CaHPO(4) x 2H(2)O (DCPD) and CaO with water or sodium phosphate buffers as liquid phase, a calcium phosphate cement was obtained. Its physical and mechanical properties, such as compressive strength, initial and final setting times, cohesion time, dough time, swelling time, dimensional and thermal behavior, and injectability were investigated by varying different parameters such as liquid to powder (L/P) ratio (0.35-0.7 ml g(-1)), molar calcium to phosphate (Ca/P) ratio (1.67-2.5) and the pH (4, 7, and 9) and the concentration (0-1 M) of the sodium phosphate buffer. The best results were obtained with the pH 7 sodium phosphate buffer at the concentration of 0.75 M. With this liquid phase, physical and mechanical properties depended on the Ca/P and L/P ratios, varying from 3 to 11 MPa (compressive strength), 6 to 10 min (initial setting time), 11 to 15 min (final setting time), 15 to 30 min (swelling time), 7 to 20 min (time of 100% injectability). The dough or working time was over 16 min. This cement expanded during its setting (1.2-5 % according to Ca/P and L/P ratios); this would allow a tight filling. Given the mechanical and rheological properties of this new DCPD/CaO-based cement, its use as root canal sealing material can be considered as classical calcium hydroxide or ZnO/eugenol-based pastes, without or with a gutta-percha point. Copyright 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 447-453, 2002

  17. Thermodynamic and microscopic equilibrium constants of molecular species formed from pyridoxal 5'-phosphate and 2-amino-3-phosphonopropionic acid in aqueous and D2O solution

    International Nuclear Information System (INIS)

    Szpoganicz, B.; Martell, A.E.

    1984-01-01

    Schiff base formation between pyridoxal 5'-phosphate (PLP) and 2-amino-3-phosphonopropionic acid (APP) has been investigated by measurement of the corresponding NMR and electronic absorption spectra. A value of 0.26 was found for the formation constant of the completely deprotonated Schiff base species, and is much smaller than the values reported for pyridoxal-β-chloroalanine and pyridoxal-O-phosphoserine. The protonation constants for the aldehyde and hydrate forms of PLP were determined in D 2 O by measurement of the variation of chemical shifts with pD (pH in D 2 O). The hydration constants of PLP were determined in a pD range 2-12, and species distributions were calculated. The protonation constants of the APP-PLP Schiff base determined by NMR in D 2 O were found to have the log values 12.54, 8.10, 6.70, and 5.95, and the species distributions were calculated for a range of pD values. Evidence is reported for hydrogen bonding involving the phosphate and phosphonate groups of the diprotonated Schiff base. The cis and trans forms of the Schiff bases were distinguished with the aid of the nuclear Overhauser effect. 43 references, 9 figures, 3 tables

  18. Hole filling and interlayer coupling in YBa2Cu3O7/PrBa2Cu3O7 superlattices

    International Nuclear Information System (INIS)

    Biagini, M.; Calandra, C.; Ossicini, S.

    1995-01-01

    Charge transfer effects in YBa 2 Cu 3 O 7 /PrBa 2 Cu 3 O 7 superlattices have been proposed by many authors as the origin of the experimentally observed strong depression of the critical temperature. We performed self-consistent LMTO-ASA calculations and found that no remarkable change in the electronic structure of the superconducting CuO 2 planes occurs in the studied structures, when the PBCO layer thickness is varied. The observed depression of the critical temperature does not seem to be originated intrinsically by a severe modification of the electronic structure or by the hole-filling mechanism. (orig.)

  19. Crystal structure of lithium disulfate, Li{sub 2}[S{sub 2}O{sub 7}], Li{sub 2}O{sub 7}S{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Logemann, Christian; Witt, Julia; Wickleder, Mathias S. [Oldenburg Univ. (Germany). Inst. of Pure and Applied Chemistry

    2013-07-01

    Li{sub 2}O{sub 7}S{sub 2}, orthorhombic, Pnma (no. 62), a = 13.177(2) Aa, b = 8.2516(7) Aa, c = 4.8547(4) Aa, V = 527.8 Aa{sup 3}, Z = 4, R{sub gt}(F) = 0.0338, wR{sub ref}(F{sup 2}) = 0.1054, T = 153 K.

  20. THE REACTION BETWEEN ZnO AND MOLTEN NA2S2O7 OR K2S2O7 FORMING NA2Zn(SO4)2 OR K2Zn(SO4)2, STUDIED BY RAMAN SPECTROSCOPY AND X-RAY DIFFRACTION

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Thorup, Niels

    2005-01-01

    Reactions between solid ZnO and molten Na2S2O7 or K2S2O7 at 500 are shown by Raman spectroscopy to be 1:1 reactions leading to solns. By lowering the temp. of the soln. melts, colorless crystals form. Raman spectra of the crystals are given and tentatively assigned. Crystal structures of the mon...... the three-dimensional network of the M2Zn(SO4)2 structures. Bond distances and angles compare well with literature values. Empirical correlations between S-O bond distances and av. O-S-O bond angles follow a previously found trend....

  1. Chemical durability and Structural approach of the glass series (40-y) Na2O-yFe2O3-5Al2O3-55P2O5-by IR, X-ray diffraction and Mössbauer Spectroscopy

    International Nuclear Information System (INIS)

    Aqdim, S; Sayouty, El H; Elouad, B; Greneche, J M

    2012-01-01

    The relationship between the composition and structure for the glasses of general composition (40-y)Na 2 O-yFe 2 O 3 -5Al 2 O 3 -55P 2 O 5 (5≤y≤20), has been studied. The chemical durability and density of these glasses increase with increasing Fe 2 O 3 content. The dissolution rate (D R ), calculated from the weight loss in distilled water at 90°C for up to 20 days was ≈ 3.10 −9 g/cm 2 /mn which is 30 times lower than that of window glass. The structure and valence states of the iron ions in the glasses were investigated using, X-ray diffraction, 57Fe Mössbauer spectrometry, potentiometric analysis, and infrared spectroscopy. Both Mössbauer spectrometry and potentiometric analysis allow to estimate both Fe 2+ and Fe 3+ contents in all these glasses. X-ray diffraction indicates that the local structure of iron phosphate glasses is related to the short range structures of NaFeP 2 O 7 . Infrared spectra indicate the formation of P–O–Fe bonds in the pyrophosphate glasses that replace P–O–Na bonds. The presence of a small content of Al 2 O 3 in the glass seems to play a role as a network modifier. The addition of Fe 2 O 3 to Al 2 O 3 in phosphate glasses favours the enhancement of the formation of pyrophosphate units because iron ions have stronger effect on the depolymerization of metaphosphate chains than the aluminium ions. Finally, the I.R spectra indicate that the presence of P-O-Fe bands of these glasses containing more than 15 mol%Fe 2 O 3 is consistent with their good chemical durability.

  2. Immobilization of Uranium Silicide in Sintered Iron-Phosphate Glass

    International Nuclear Information System (INIS)

    Mateos, Patricia; Russo, Diego; Rodriguez, Diego; Heredia, A; Sanfilippo, M.; Sterba, Mario

    2003-01-01

    This work is a continuation of a previous one performed in vitrification of uranium silicide in borosilicate and iron-silicate glasses, by sintering.We present the results obtained with an iron-phosphate glass developed at our laboratory and we compare this results with those obtained with the above mentioned glasses. The main objective was to develop a method as simple as possible, so as to get a monolithic glass block with the appropriate properties to be disposed in a deep geological repository.The thermal transformation of the uranium silicide was characterized by DTA/TG analysis and X-ray diffraction.We determined the evolution of the crystalline phases and the change in weight.Calcined uranium silicide was mixed with natural U 3 O 8 , the amount of U 3 O 8 was calculated to simulate an isotopic dilution of 4%.This material was mixed with powdered iron-phosphate glass (in wt.%: 64,9 P 2 O 5 ; 22,7 Fe 2 O 3 ; 8,1 Al 2 O 3 ; 4,3 Na 2 O) in different proportions (in wt%): 7%, 10% y 15%.The powders were pressed and sintered at temperatures between 585 y 670 °C. Samples of the sintered pellet were prepared for the lixiviation tests (MCC-1P: monolithic samples; deionised water; 90° C; 7, 14 and 28 days).The samples showed a quite good durability (0,6 g.m -2 .day -1 ), similar to borosilicate glasses.The microstructure of the glass samples showed that the uranium particles are much better integrated to the glass matrix in the iron-phosphate glasses than in the borosilicate or iron-silicate glasses.We can conclude that the sintered product obtained could be a good alternative for the immobilization of nuclear wastes with high content of uranium, as the ones arising from the conditioning of research reactors spent fuels

  3. Conductivity fluctuation and superconducting parameters of the YBa2Cu3-x (PO4) x O7-δ material

    International Nuclear Information System (INIS)

    Rojas Sarmiento, M.P.; Uribe Laverde, M.A.; Vera Lopez, E.; Landinez Tellez, D.A.; Roa-Rojas, J.

    2007-01-01

    Synthesis of the YBa 2 Cu 3- x (PO 4 ) x O 7- δ superconducting material by the standard solid-state reaction is reported. DC resistivity measurements reveal the improvement of the critical temperature (T C ) when substitution of phosphate in the Cu sites is performed. A bulk T C =97 K was determined by the criterion of the maximum in the temperature derivative of electrical resistivity. Structure characterization by means the X-ray diffraction technique shows the crystalline appropriated distribution of PO 4 into the CuO 2 superconducting planes. In order to examine the effect of phosphates on the pairing mechanism close to T C , conductivity fluctuation analysis was performed by the method of logarithmic temperature derivative of the conductivity excess. We found the occurrence of Gaussian-like fluctuations. The correlations of the critical exponents with the dimensionality of the fluctuation system for each Gaussian regime were performed by using the Aslamazov-Larkin theory. The Ginzburg number for this superconducting material is predicted and the critical magnetic fields, critical current density and the jump in the specific heat at the critical temperature are theoretically determined

  4. Effect of boron oxide addition on fibre drawing, mechanical properties and dissolution behaviour of phosphate-based glass fibres with fixed 40, 45 and 50 mol% P2O5.

    Science.gov (United States)

    Sharmin, Nusrat; Parsons, Andrew J; Rudd, Chris D; Ahmed, Ifty

    2014-11-01

    Previous studies investigating manufacture of phosphate-based glass fibres from glasses fixed with P2O5 content less than 50 mol% showed that continuous manufacture without breakage was very difficult. In this study, nine phosphate-based glass formulations from the system P2O5-CaO-Na2O-MgO-B2O3 were prepared with P2O5 contents fixed at 40, 45 and 50 mol%, where Na2O was replaced by 5 and 10 mol% B2O3 and MgO and CaO were fixed to 24 and 16 mol%, respectively. The effect of B2O3 addition on the fibre drawing, fibre mechanical properties and dissolution behaviour was investigated. It was found that addition of 5 and 10 mol% B2O3 enabled successful drawing of continuous fibres from glasses with phosphate (P2O5) contents fixed at 40, 45 and 50 mol%. The mechanical properties of the fibres were found to significantly increase with increasing B2O3 content. The highest tensile strength (1200 ± 130 MPa) was recorded for 45P2O5-16CaO-5Na2O-24MgO-10B2O3 glass fibres. The fibres were annealed, and a comparison of the mechanical properties and mode of degradation of annealed and non-annealed fibres were investigated. A decrease in tensile strength and an increase in tensile modulus were observed for the annealed fibres. An assessment of the change in mechanical properties of both the annealed and non-annealed fibres was performed in phosphate-buffered saline (PBS) at 37℃ for 28 and 60 days, respectively. Initial loss of mechanical properties due to annealing was found to be recovered with degradation. The B2O3-containing glass fibres were found to degrade at a much slower rate as compared to the non-B2O3-containing fibres. Both annealed and non-annealed fibres exhibited a peeling effect of the fibre's outer layer during degradation. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  5. LiFePO4 Nanostructures Fabricated from Iron(III) Phosphate (FePO4 x 2H2O) by Hydrothermal Method.

    Science.gov (United States)

    Saji, Viswanathan S; Song, Hyun-Kon

    2015-01-01

    Electrode materials having nanometer scale dimensions are expected to have property enhancements due to enhanced surface area and mass/charge transport kinetics. This is particularly relevant to intrinsically low electronically conductive materials such as lithium iron phosphate (LiFePO4), which is of recent research interest as a high performance intercalation electrode material for Li-ion batteries. Many of the reported works on LiFePO4 synthesis are unattractive either due to the high cost of raw materials or due to the complex synthesis technique. In this direction, synthesis of LiFePO4 directly from inexpensive FePO4 shows promise.The present study reports LiFePO4 nanostructures prepared from iron (III) phosphate (FePO4 x 2H2O) by precipitation-hydrothermal method. The sintered powder was characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Inductive coupled plasma-optical emission spectroscopy (ICP-OES), and Electron microscopy (SEM and TEM). Two synthesis methods, viz. bulk synthesis and anodized aluminum oxide (AAO) template-assisted synthesis are reported. By bulk synthesis, micro-sized particles having peculiar surface nanostructuring were formed at precipitation pH of 6.0 to 7.5 whereas typical nanosized LiFePO4 resulted at pH ≥ 8.0. An in-situ precipitation strategy inside the pores of AAO utilizing the spin coating was utilized for the AAO-template-assisted synthesis. The template with pores filled with the precipitate was subsequently subjected to hydrothermal process and high temperature sintering to fabricate compact rod-like structures.

  6. Intermediate magnetization state and competing orders in Dy2Ti2O7 and Ho2Ti2O7

    Science.gov (United States)

    Borzi, R. A.; Gómez Albarracín, F. A.; Rosales, H. D.; Rossini, G. L.; Steppke, A.; Prabhakaran, D.; Mackenzie, A. P.; Cabra, D. C.; Grigera, S. A.

    2016-01-01

    Among the frustrated magnetic materials, spin-ice stands out as a particularly interesting system. Residual entropy, freezing and glassiness, Kasteleyn transitions and fractionalization of excitations in three dimensions all stem from a simple classical Hamiltonian. But is the usual spin-ice Hamiltonian a correct description of the experimental systems? Here we address this issue by measuring magnetic susceptibility in the two most studied spin-ice compounds, Dy2Ti2O7 and Ho2Ti2O7, using a vector magnet. Using these results, and guided by a theoretical analysis of possible distortions to the pyrochlore lattice, we construct an effective Hamiltonian and explore it using Monte Carlo simulations. We show how this Hamiltonian reproduces the experimental results, including the formation of a phase of intermediate polarization, and gives important information about the possible ground state of real spin-ice systems. Our work suggests an unusual situation in which distortions might contribute to the preservation rather than relief of the effects of frustration. PMID:27558021

  7. Formulation of single super phosphate fertilizer from rock phosphate of Hazara, Pakistan

    Directory of Open Access Journals (Sweden)

    Matiullah Khan

    2012-05-01

    Full Text Available Phosphorus deficiency is wide spread in soils of Pakistan. It is imperative to explore the potential and economics of indigenous Hazara rock phosphate for preparation of single super phosphate fertilizer. For the subject study rock phosphate was collected from Hazara area ground at 160 mesh level with 26% total P2O5 content for manual preparation of single super phosphate fertilizer. The rock phosphate was treated with various concentrations of sulfuric acid (98.9%, diluted or pure in the field. The treatments comprised of 20 and 35% pure acid and diluted with acid-water ratios of 1:5, 1:2, 1:1 and 2:1 v/v for acidulation at the rate of 60 liters 100 kg-1 rock phosphate. The amount was prior calculated in the laboratory for complete wetting of rock phosphate. A quantity of 150 kg rock phosphate was taken as treatment. The respective amount of acid was applied with the spray pump of stainless steel or poured with bucket. After proper processing, chemical analysis of the products showed a range of available P2O5 content from 9.56 to 19.24% depending upon the amount of acid and its dilution. The results reveal at that 1:1 dilutions gave the highest P2O5 content (19.24%, lowest free acid (6 % and 32% weight increase. The application of acid beyond or below this combination either pure or diluted gave hygroscopic product and higher free acids. The cost incurred upon the manual processing was almost half the prevailing rates in the market. These results lead to conclude that application of sulfuric acid at the rate of 60 liters 100 kg-1 with the dilution of 50% (v/v can yield better kind of SSP from Hazara rock phosphate at lower prices.

  8. A new three-dimensional cobalt phosphate: Co 5(OH 2) 4(HPO 4) 2(PO 4) 2

    Science.gov (United States)

    Han, Zhangang; Tian, Aixiang; Peng, Jun; Zhai, Xueliang

    2006-10-01

    A three-dimensional (3D) cobalt phosphate: Co 5(OH 2) 4(HPO 4) 2(PO 4) 2 ( 1), has been synthesized by hydrothermal reaction and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic techniques. The title compound is a template free cobalt phosphate. Compound 1 exhibits a complex net architecture based on edge- and corner-sharing of CoO 6 and PO 4 polyhedra. The magnetic susceptibility measurements indicated that the title compound obeys Curie-Weiss behavior down to a temperature of 17 K at which an antiferromagnetic phase transition occurs.

  9. Energy conversion from aluminium and phosphate rich solution via ZnO activation of aluminium

    Energy Technology Data Exchange (ETDEWEB)

    Slaughter, Gymama, E-mail: gslaught@umbc.edu; Sunday, Joshua; Stevens, Brian

    2015-08-01

    Electrochemical power sources have motivated intense research efforts in the development of alternative ‘green’ power sources for ultra-low powered bioelectronic devices. Biofuel cells employ immobilized enzymes to convert the available chemical energy of organic fuels directly into electricity. However, biofuel cells are limited by short lifetime due to enzyme inactivation and frequent need to incorporate mediators to shuttle electrons to the final electron acceptor. In this context, other electrochemical power sources are necessary in energy conversion and storage device applications. Here we report on the fabrication and characterization of a membrane-free aluminium/phosphate cell based on the activation of aluminium (Al) using ZnO nanocrystal in an Al/phosphate cell as a ‘green’ alternative to the traditional enzymatic biofuel cells. The hybrid cell operates in neutral phosphate buffer solution and physiological saline buffer. The ZnO modifier in the phosphate rich electrolyte activated the pitting of Al resulting in the production of hydrogen, as the reducing agent for the reduction of H{sub 2}PO{sub 4}{sup −} ions to HPO{sub 3}{sup 2−} ions at a formal potential of −0.250 V vs. Ag/AgCl. Specifically, the fabricated cell operating in phosphate buffer and physiological saline buffer exhibit an open-circuit voltage of 0.810 V and 0.751 V and delivered a maximum power density of 0.225 mW cm{sup −2} and 1.77 mW cm{sup −2}, respectively. Our results demonstrate the feasibility of generating electricity by activating Al as anodic material in a hybrid cell supplied with phosphate rich electrolyte. Our approach simplifies the construction and operation of the electrochemical power source as a novel “green” alternative to the current anodic substrates used in enzymatic biofuel cells for low power bioelectronics applications. - Graphical abstract: Display Omitted - Highlights: • ZnO activation of metallic Al for generating electricity for

  10. Doping of low-T{sub g} phosphate glass with Al{sub 2}O{sub 3}, B{sub 2}O{sub 3} and SiO{sub 2}: Part I- effect on glass property and stability

    Energy Technology Data Exchange (ETDEWEB)

    Rajbhandari, P., E-mail: p.rajbhandari@sheffield.ac.uk [UCCS UMR-CNRS 8181, Universite de Lille1, Villeneuve d' Ascq (France); Montagne, L. [UCCS UMR-CNRS 8181, Universite de Lille1, Villeneuve d' Ascq (France); Tricot, G. [UCCS UMR-CNRS 8181, Universite de Lille1, Villeneuve d' Ascq (France); LASIR UMR-CNRS 8516, Universite de Lille1, Villeneuve d' Ascq (France)

    2016-11-01

    A zinc alkali pyrophosphate system 46.6ZnO-20Na{sub 2}O-33.5P{sub 2}O{sub 5} presenting low-T{sub g} (339 °C) and good thermal stability has been doped with (1–4) mol% of Al{sub 2}O{sub 3}, B{sub 2}O{sub 3} and SiO{sub 2} to improve the stability of the glass with a minimal increase in glass transition temperature (T{sub g}). XRD and 1D {sup 31}P solid state NMR were used to monitor the isothermal crystallization process occurring at 130 °C above T{sub g}. If the Al{sub 2}O{sub 3} and B{sub 2}O{sub 3} doping significantly improved thermal stability, this property was marginally affected by SiO{sub 2} doping. Viscosity measurements were performed to observe the crystallization effects induced by the doping. It is noteworthy that the T{sub g} values of all the doped compositions with improved stability presented in this work are below 400 °C. Raman spectroscopy, 1D {sup 31}P, {sup 27}Al, {sup 11}B and {sup 29}Si solid state NMR were carried out to determine the structural modifications and coordination states of the doping elements all along the composition line. - Highlights: • Low-Tg phosphate glasses doped with Al{sub 2}O{sub 3}, B{sub 2}O{sub 3} and SiO{sub 2} have been formulated. • Thermal stability of the glass has been improved significantly. • The structural modification induced by doping elements has been studied by employing solid state NMR technique.

  11. Hydrothermal synthesis of copper zirconium phosphate hydrate [Cu(OH)2Zr(HPO4)2·2H2O] and an investigation of its lubrication properties in grease.

    Science.gov (United States)

    Zhang, Xiaosheng; Xu, Hong; Zuo, Zhijun; Lin, Zhi; Ferdov, Stanislav; Dong, Jinxiang

    2013-08-28

    Copper zirconium phosphate hydrate (Cu(OH)2Zr(HPO4)2·2H2O, hereafter referred to as Cu-α-ZrP) with high crystallinity was directly synthesized in a NaF-CuO-ZrO-P2O5-H2O system under hydrothermal conditions. The copper ion was confirmed to be an exchangeable cation in the Cu-α-ZrP through elemental analysis and a proton ion exchange process. The crystal structure of the Cu-α-ZrP was determined ab initio by using X-ray powder diffraction data. In the structure, the CuO6 octahedron would be located in an exchangeable atom position. Moreover, Cu-α-ZrP was evaluated as an additive in grease in a four ball test. The maximum nonseizure load (PB, representing the load-carrying capacity) of the base grease containing Cu-α-ZrP was increased from 353 to 1235 N. The excellent load-carrying capacity may be explained by the easier adherence of the material to the worn surface forming a tight protective film.

  12. Electronic structure and vibrational properties of KRbAl{sub 2}B{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V.V. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Adichtchev, S.V. [Laboratory of Condensed Matter Spectroscopy, Institute of Automation and Electrometry, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Bazarov, B.G.; Bazarova, Zh.G. [Laboratory of Oxide Systems, Baikal Institute of Nature Management, SB RAS, Ulan-Ude 47, 670047 (Russian Federation); Gavrilova, T.A. [Laboratory of Nanodiagnostics and Nanolithography, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Grossman, V.G. [Laboratory of Oxide Systems, Baikal Institute of Nature Management, SB RAS, Ulan-Ude 47, 670047 (Russian Federation); Kesler, V.G. [Laboratory of Physical Principles for Integrated Microelectronics, Institute of Semiconductor Physics, Novosibirsk, 630090 (Russian Federation); Meng, G.S. [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, P.O. Box 2711, Beijing 100190 (China); Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Lin, Z.S., E-mail: zslin@mail.ipc.ac.cn [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, P.O. Box 2711, Beijing 100190 (China); Surovtsev, N.V. [Laboratory of Condensed Matter Spectroscopy, Institute of Automation and Electrometry, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

    2013-03-15

    Graphical abstract: With the KRbAl{sub 2}B{sub 2}O{sub 7} powder formed by solid state synthesis (left), Raman spectrum (right upper) and XPS valence electronic states (right lower) were measured, agreed with the first-principles results. Highlights: ► KRbAl{sub 2}B{sub 2}O{sub 7} powder was obtained by solid state synthesis. ► Vibrational properties of KRbAl{sub 2}B{sub 2}O{sub 7} were determined by unpolarized Raman spectrum. ► Electronic structures of KRbAl{sub 2}B{sub 2}O{sub 7} were measured by XPS. ► Experimental electronic structure is consistent with the first-principles result. ► KRbAl{sub 2}B{sub 2}O{sub 7} has a noticeable refractive indices increase and small NLO effects decrease compared to K{sub 2}Al{sub 2}B{sub 2}O{sub 7}. - Abstract: The physical properties of KRbAl{sub 2}B{sub 2}O{sub 7} have been considered in comparison with those of K{sub 2}Al{sub 2}B{sub 2}O{sub 7} and Rb{sub 2}Al{sub 2}B{sub 2}O{sub 7}. The vibrational parameters of KRbAl{sub 2}B{sub 2}O{sub 7} have been measured by Raman spectroscopy as very similar to those of K{sub 2}Al{sub 2}B{sub 2}O{sub 7}. The electronic structures of KRbAl{sub 2}B{sub 2}O{sub 7} have been evaluated by X-ray photoelectron spectroscopy and ab initio computations using CASTEP package. A noticeable refractive indices increase and small decrease of nonlinear optical properties have been found in KRbAl{sub 2}B{sub 2}O{sub 7} in reference to optical parameters of K{sub 2}Al{sub 2}B{sub 2}O{sub 7}.

  13. Uranium and thorium based phosphate matrix: synthesis, characterizations and lixiviation

    International Nuclear Information System (INIS)

    Dacheux, N.

    1995-03-01

    In the framework of the search for a ceramic material usable in the radioactive waste storage, uranium and thorium phosphates have been investigated. Their experimental synthesis conditions have been entirely reviewed, they lead to the preparation of four new compounds: U(UO 2 )(PO 4 ) 2 , U 2 O(PO 4 ) 2 , UCIPO 4 , 4H 2 O, and Th 4 (PO 4 ) 4 P 2 O 7 . Experimental evidenced are advanced for non existent compounds such as: U 3 (PO 4 ) 4 , U 2 O 3 P 2 O 7 and Th 3 (PO 4 ) 4 . Characterization by several techniques (X-rays and neutron powder diffractions, UV-Visible and Infra-red spectroscopies, XPS,...) were performed. The ab initio structure determination of U(UO 2 )(PO 4 ) 2 has been achieved by X-rays and refined by neutron diffractions. Through its physico-chemical analysis, we found that this compound was a new mixed valence uranium phosphate in which U 4+ and UO 2 2+ ions are ordered in pairs along parallel chains according to a new type of arrangement. Reaction mechanism, starting from UCIPO 4 , 4H 2 O and based on redox processes of uranium in solid state was set up. From two main matrices U(UO 2 )(PO 4 ) 2 and Th 4 (PO 4 ) 4 P 2 O 7 , solid solutions were studied. They consist of replacement of U(IV) by Th(IV) and reversely. The leaching tests on pure, loaded and doped matrices were performed in terms of storage time, pH of solutions, and determined by the use of solids labelled with 230 U or by the measurement of uranyl concentration by Laser-Induced Time-Resolved Spectro-fluorimetry. Average concentration of uranium in the liquid phase is around 10 -4 M to 10 -6 M. Taking into account the very low solubilities of the studied phosphate ceramics, we estimated their chemical performances promising as an answer to the important nuclear waste problem, if we compare them to the glasses used at the present time. (author)

  14. Effect of reducing conditions of synthesis on the character of the crystallization of phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Alekseeva, I.P.; Karapetyan, G.O.; Milyukov, E.M.; Rusan, V.V.

    1986-03-01

    The authors investigate the effect of synthesis conditions on the properties of phosphate glasses with a high concentration of rare-earth elements (REE) which are promising materials for quantum electronics. Particular attention was paid to the character of the crystallization of the glasses. A model glass of the composition La/sub 2/O/sub 3/ X 3P/sub 2/O/sub 5/ was studied which is transparent in the visible and near-IR regions of the spectrum and produced commercially.

  15. Irradiation-induced amorphization of Cd2Nb2O7 pyrochlore

    International Nuclear Information System (INIS)

    Meldrum, A.; White, C. W.; Keppens, V.; Boatner, L. A.; Ewing, R. C.

    2001-01-01

    Several investigations have recently been undertaken in order to achieve a more complete understanding of the radiation-damage mechanisms in A 2 B 2 O 7 pyrochlore-structure compounds. The present work represents the first systematic study of the irradiation-induced amorphization of a pyrochlore with A- and B-site cation valences of +2 and +5, respectively. Relatively large single crystals of Cd 2 Nb 2 O 7 were grown for these experiments. In situ ion-irradiation experiments were carried out in a transmission electron microscope in conjunction with ex situ Rutherford backscattering measurements of ion-irradiated Cd 2 Nb 2 O 7 single crystals. Cd 2 Nb 2 O 7 can be amorphized in situ by Ne or Xe ions at temperatures up to 480 and 620 K, respectively. At room temperature, the amorphization fluence was 36 times higher for 280 keV Ne + than for 1200 keV Xe 2+ , corresponding to a displacement dose that was higher by a factor of 3. Disordering of Cd and Nb over the available cation sites occurs at intermediate ion doses prior to amorphization. The temperature dependence of the amorphization dose is modeled, and the results are compared to those of a previous model. The bulk-sample Rutherford backscattering spectroscopy (RBS) results were generally consistent with the in situ TEM measurements. Effects of crystallographic orientation and ion charge state had relatively little effect on the damage accumulation in bulk crystals. The RBS data are consistent with a defect-accumulation, cascade-overlap model of amorphization of Cd 2 Nb 2 O 7 , as are the in situ TEM observations

  16. Stability of the high pressure phase Fe3S2 up to Earth's core pressures in the Fe-S-O and the Fe-S-Si systems

    Science.gov (United States)

    Zurkowski, C. C.; Chidester, B.; Davis, A.; Brauser, N.; Greenberg, E.; Prakapenka, V. B.; Campbell, A.

    2017-12-01

    Earth's core is comprised of an iron-nickel alloy that contains 5-15% of a light element component. The abundance and alloying capability of sulfur, silicon and oxygen in the bulk Earth make them important core alloy candidates; therefore, the high-pressure phase equilibria of the Fe-S-O and Fe-S-Si systems are relevant for understanding the possible chemistry of Earth's core. Previously, a Fe3S2 phase was recognized as a low-pressure intermediate phase in the Fe-FeS system that is stable from 14-21 GPa, but the structure of this phase has not been resolved. We report in-situ XRD and chemical analysis of recovered samples to further examine the stability and structure of Fe3S2 as it coexists with other phases in the Fe-S-O and Fe-S-Si systems. In situ high P-T synchrotron XRD experiments were conducted in the laser-heated diamond anvil cell to determine the equilibrium phases in Fe75S7O18 and Fe80S5Si15 compositions between 30 and 174 GPa and up to 3000 K. In the S,O-rich samples, an orthorhombic Fe3S2 phase coexists with hcp-Fe, Fe3S and FeO and undergoes two monoclinic distortions between 60 and 174 GPa. In the S,Si-rich samples, the orthorhombic Fe3S2 phase was observed up to 115 GPa. With increasing pressure, the Fe3S2 phase becomes stable to higher temperatures in both compositions, suggesting possible Fe3(S,O)2 or Fe3(S,Si)2 solid solutions. SEM analysis of a laser heated Fe75S7O18 sample recovered from 40 GPa and 1450 K confirms a Fe3(S,O)2 phase with O dissolved into the structure. Based on the current melting data in the Fe-S-O and Fe-S-Si systems, the Fe3(S,O)2 stability field intersects the solidus in the outer core and could be a possible liquidus phase in Fe,S,O-rich planetary cores, whereas Fe3S is the stable sulfide at outer core pressures in Fe,S,Si-rich systems.

  17. Synthesis, structure, and luminescence properties of In{sub 2}Ge{sub 2}O{sub 7}/SnO{sub 2} core-shell nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sunghoon; An, Soyeon; Jin, Changhyun; Lee, Chongmu [Inha University, Incheon (Korea, Republic of)

    2012-09-15

    In{sub 2}Ge{sub 2}O{sub 7}/SnO{sub 2} core-shell nanowires were synthesized by using a two-step process: thermal evaporation of a mixture of In and Ge powders and atomic layer deposition of SnO{sub 2}. The core-shell nanowires were characterized using by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and photoluminescence spectroscopy. The In{sub 2}Ge{sub 2}O{sub 7} cores in these core-shell nanowires varied from 50 to 100 nanometers in diameter and up to a few hundreds of micrometers in length, and the SnO{sub 2} shell layer thickness ranged from 5 to 15 nm. Photoluminescence measurements showed that the In{sub 2}Ge{sub 2}O{sub 7} nanowires had a weak broad violet emission band centered at approximately 405 nm. In contrast, the In{sub 2}Ge{sub 2}O{sub 7}/SnO{sub 2} core-shell nanowires had a taller blue-violet emission peak at approximately 440 nm. The optimum shell layer thickness of the In{sub 2}Ge{sub 2}O{sub 7}/SnO{sub 2} core-shell nanowires for the highest PL intensity was found to be 15 nm. Our results also showed that the intensity of the blue-violet emission was increased further by thermal annealing in an Ar atmosphere. The origins of the change on and the enhancement of the luminescence of the In{sub 2}Ge{sub 2}O{sub 7} nanowires by SnO{sub 2} coating and annealing are discussed.

  18. Controls on O2 Production in Cyanobacterial Mats and Implications for Earth's Oxygenation

    Science.gov (United States)

    Dick, Gregory J.; Grim, Sharon L.; Klatt, Judith M.

    2018-05-01

    Cyanobacterial mats are widely assumed to have been globally significant hot spots of biogeochemistry and evolution during the Archean and Proterozoic, but little is known about their quantitative contributions to global primary productivity or Earth's oxygenation. Modern systems show that mat biogeochemistry is the outcome of concerted activities and intimate interactions between various microbial metabolisms. Emerging knowledge of the regulation of oxygenic and sulfide-driven anoxygenic photosynthesis by versatile cyanobacteria, and their interactions with sulfur-oxidizing bacteria and sulfate-reducing bacteria, highlights how ecological and geochemical processes can control O2 production in cyanobacterial mats in unexpected ways. This review explores such biological controls on O2 production. We argue that the intertwined effects of light availability, redox geochemistry, regulation and competition of microbial metabolisms, and biogeochemical feedbacks result in emergent properties of cyanobacterial mat communities that are all critical yet largely overlooked mechanisms to potentially explain the protracted nature of Earth's oxygenation.

  19. High Temperature NMR Studies of the Glass-Crystal Transition in the Cs2S2O7-V2O5 System

    DEFF Research Database (Denmark)

    Lapina, Olga B.; Terskikh, Viktor V.; Shubin, Aleksander A.

    1997-01-01

    133Cs and 51V NMR spectra have been recorded of Cs2S2O7 and the catalytically important Cs2S2O7-V2O5 mixtures in the temperature range 20 - 550 C. A high mobility of Cs+ in the solid Cs2S2O7 was observed. The transformation from glassy state to crystalline state was investigated for the compositi...

  20. Redetermination of clinobaryl­ite, BaBe2Si2O7

    Science.gov (United States)

    Domizio, Adrien J. Di; Downs, Robert T.; Yang, Hexiong

    2012-01-01

    Clinobaryl­ite, ideally BaBe2Si2O7 (chemical name barium diberyllium disilicate), is a sorosilicate mineral and dimorphic with baryl­ite. It belongs to a group of compounds characterized by the general formula BaM 2+ 2Si2O7, with M 2+ = Be, Mg, Fe, Mn, Zn, Co, or Cu, among which the Be-, Fe-, and Cu-members have been found in nature. The crystal structure of clinobaryl­ite has been re-examined in this study based on single-crystal X-ray diffraction data collected from a natural sample from the type locality (Khibiny Massif, Kola Peninsula, Russia). The structure of clinobaryl­ite can be considered as a framework of BeO4 and SiO4 tetra­hedra, with one of the O atoms coordinated to two Be and one Si, one coordinated to two Si, and two O atoms coordinated to one Si and one Be atom. The BeO4 tetra­hedra share corners, forming chains parallel to the c axis, which are inter­linked by the Si2O7 units oriented parallel to the a axis. The Ba2+ cations (site symmetry m..) are in the framework channels and are coordinated by eleven O atoms in form of an irregular polyhedron. The Si—Obr (bridging O atom, at site symmetry m..) bond length, the Si—Onbr (non-bridging O atoms) bond lengths, and the Si—O—Si angle within the Si2O7 unit are in marked contrast to the corresponding values determined in the previous study [Krivovichev et al. (2004 ▶). N. Jb. Miner. Mh. pp. 373–384]. PMID:23125568

  1. Surface Modification of LiMn2O4 for Lithium Batteries by Nanostructured LiFePO4 Phosphate

    Directory of Open Access Journals (Sweden)

    B. Sadeghi

    2012-01-01

    Full Text Available LiMn2O4 spinel cathode materials have been successfully synthesized by solid-state reaction. Surface of these particles was modified by nanostructured LiFePO4 via sol gel dip coating method. Synthesized products were characterized by thermally analyzed thermogravimetric and differential thermal analysis (TG/DTA, X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, and energy dispersive X-ray spectroscopy (EDX. The results of electrochemical tests showed that the charge/discharge capacities improved and charge retention of battery enhanced. This improved electrochemical performance is caused by LiFePO4 phosphate layer on surfaces of LiMn2O4 cathode particles.

  2. Optical properties of Eu3+ & Tb3+ ions doped alkali oxide (Li2O/ Na2O/ K2O) modified boro phosphate glasses for red, green lasers and display device applications

    Science.gov (United States)

    Moulika, G.; Sailaja, S.; Reddy, B. Naveen Kumar; Reddy, V. Sahadeva; Dhoble, S. J.; Reddy, B. Sudhakar

    2018-04-01

    In this article we report on alkali oxide modified borophosphate glasses doped with Eu3+and Tb3+ ions, with the chemical composition of 69.5 B2O3+10P2O5 + 10CaF2 + 5 Li2O+ 5ZnO+ R+ 0.5 Eu2O3 [where R = 5 (LiO2/Na2O/K2O)] have been prepared by conventional melt quenching technique, and the spectroscopic properties of the prepared glasses have been studied by XRD, Optical absorption, excitation and emission spectral analysis. XRD spectrum of the glasses have shown the amorphous nature of the glasses. The red emission corresponding to 5D0 → 7F2 (613 nm) transition was observed under the excitation of 394 nm wavelength, corresponding to Eu3+ ions, for all the prepared glasses. For Eu3+ ion doped glasses, emission bands were observed, such as; 5D1→ 7F1 (538 nm), 5D0→ 7F0 (580 nm), 5D0→ 7F1 (592 nm), 5D0→ 7F2 (613 nm), 5D0→ 7F3 (613 nm) and 5D0→ 7F4 (702 nm) are identified. In the case of Tb3+ ion doped glasses, four emission lines were observed, such as 5D4→ (7F6, 7F5, 7F4), which are located at 489 nm, 545 nm and 585 nm, respectively, after the samples were excited with 376 nm ultraviolet source. The green emission corresponding to 5D4 → 7F5 (543 nm) transition was observed under excitation wavelength 376 nm of the Tb3+ ions for all the prepared glasses. For all these emission bands, the decay curves were recorded to evaluate the emission life times. The mechanism underlying the observed emission from the glasses was explained in terms of energy levels.

  3. Rare earth oxide reinforced Al{sub 2}O{sub 3}-TiO{sub 2} ceramics for inert coating of metallic parts for petroleum extraction

    Energy Technology Data Exchange (ETDEWEB)

    Yadava, Yoggendra Prasad; Rego, Sheila Alves Bezerra da Costa; Ferreira, Ricardo Artur Sanguinetti [Universidade Federal de Pernambuco (UFPE), Recife (Brazil)

    2012-07-01

    Recent findings of largest known pre-salt petroleum reservoir in Brazil have created an intense demand for new materials capable of withstanding direct contact with the crude petroleum as it is a highly corrosive and chemically reactive fluid. Petroleum drilling equipment, storage tanks and transportation systems suffer from constant physical stress caused by chemical attack of crude petroleum on its structure. Ceramics are materials with high chemical stability in hostile environment and therefore can be used as an inert coating material to resolve such problems. To date, ceramics based on alumina are most widely used in practice where there is demand for high mechanical strength and high fracture toughness. However intrinsic fragility of ceramics is still a fatal factor for their use in mechanical structures. To improve these characteristics, usually ceramics are reinforced with one or more ceramic additives. Mechanical properties of alumina based ceramics improve considerably with the addition of TiO{sub 2}, TiN, ZrO{sub 2} etc. ceramic additives. Nucleation and propagation of cracks is a major problem for ceramic coating applications. Initial studies show that addition of small percentages of rare earth oxides can increase the toughness of the alumina based ceramics. In the present work, we have produced rare-earth oxide (CeO{sub 2}) reinforced Al{sub 2}O{sub 3}-TiO{sub 2} ceramics in proportions of 5-20 wt% TiO{sub 2} and 2%wt% CeO{sub 2} through thermomechanical processing and sintering techniques and studied there microstructural characteristics and mechanical properties. To evaluate the potential of these ceramics as inert coatings for crude petroleum extraction, storage and transportation systems, we have studied the physic-chemical and mechanical stability of these ceramics in crude petroleum environment. Our studies presented satisfactory results in terms of physic-chemical and mechanical stability of these materials for the use of 2wt% of CeO{sub 2

  4. Crystallisation of Ba1-xSrxZn2Si2O7 from BaO/SrO/ZnO/SiO2 glass with different ZrO2 and TiO2 concentrations

    Science.gov (United States)

    Vladislavova, Liliya; Kracker, Michael; Zscheckel, Tilman; Thieme, Christian; Rüssel, Christian

    2018-04-01

    The effect of different nucleation agents such as ZrO2 and TiO2 was investigated for a first time with respect to their crystallisation behaviour in the glass system BaO-SrO-ZnO-SiO2. In all studied glasses, a Ba1-xSrxZn2Si2O7 (0.1 ≤ x ≤ 0.9) solid solution crystallized. This phase was first described in 2015 to possess a similar structure as the high temperature phase of BaZn2Si2O7 and a thermal expansion close to zero or even negative. It may find applications e.g. as cook panels, telescope mirrors, and furnace windows. Kinetic parameters of the crystallisation process were determined by supplying different heating rates in a differential scanning calorimeter (DSC). The results were evaluated using the equations of Ozawa and Kissinger with respect to the activation energies. Furthermore, the Ozawa method was used for the determination of Avrami parameters, which provides further information on the nucleation and crystallisation processes. Scanning electron microscopy including electron backscatter diffraction (EBSD) was used to characterise the microstructure, to determine the crystallite size and the crystal orientation. For the characterisation of the occurring crystalline phases, X-ray diffraction was used.

  5. Phytic acid derived bioactive CaO-P2O5-SiO2 gel-glasses.

    Science.gov (United States)

    Li, Ailing; Qiu, Dong

    2011-12-01

    The possibility of using phytic acid as a precursor to synthesize CaO-P(2)O(5)-SiO(2) glasses by sol-gel method has been explored and the pseudo ternary phase diagram has been established. It was shown that gel-glasses over a broader range of compositions could be prepared compared to other phosphorus precursors or melt-quenching method. Furthermore, phytic acid was found to assist calcium being incorporated into glass networks. In vitro tests in simulated body fluid (SBF) were performed on the above gel-glasses and it was found that they were bioactive over a much broader compositional range especially at high phosphate content, thus enabling one to design bioactive materials with various degradation rates by adjusting the phosphate content.

  6. Critical current density in (YBa2Cu3O7−δ)1−x–(PrBa2Cu3O7−δ)x melt-textured composites  

    DEFF Research Database (Denmark)

    Opata, Yuri Aparecido; Monteiro, João Frederico Haas Leandro; Jurelo, Alcione Roberto

    2018-01-01

    Melt textured (YBa2Cu3O7−δ)1−x–(PrBa2Cu3O7−δ)x composites (x = 0.00 and x = 0.05) were grown using the top seeding method. The effect of the PrBa2Cu3O7−δ phase on the growth process and the modification of the microstructure as well as on the physical properties was analyzed. X-ray analyses...... indicated that both pure and Pr-doped samples present an orthorhombic superconducting phase. From resistivity measurements for YBa2Cu3O7−δ and (YBa2Cu3O7−δ)0.95–(PrBa2Cu3O7−δ)0.05 samples, the Tcab did not change and was around 90.5 K. However, from magnetic measurements, the superconductivity was observed...... in critical temperatures TC = 92.9 K and 92.4 K for YBa2Cu3O7−δ and (YBa2Cu3O7−δ)0.95–(PrBa2Cu3O7−δ)0.05 samples, respectively. The YBa2Cu3O7−δ sample showed higher critical current densities than those shown by the (YBa2Cu3O7−δ)0.95–(PrBa2Cu3O7−δ)0.05 sample, with values of JC = 5.85 × 105 A/cm2 and 4...

  7. A basic study on capture and solidification of rare earth nuclide (Nd) in LiCl-KCl eutectic salt using an inorganic composite with Li{sub 2}OAl{sub 2}O{sub 3}- SiO{sub 2}-B{sub 2}O{sub 3} systems

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Na Young; Eum, Hee Chul; Park, Hwan Seo; Ahn, Do Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-03-15

    The pyroprocessing of spent nuclear fuel generates LiCl-KCl eutectic waste salt containing radioactive rare earth nuclides. It is necessary to develop a simple process for the treatment of LiCl-KCl eutectic waste in a hot-cell facility. In this study, capture and solidification of a rare earth nuclide (Nd) in LiCl-KCl eutectic salt using an inorganic composite with a Li{sub 2}OAl{sub 2}O{sub 3}- SiO{sub 2}-B{sub 2}O{sub 3} system was conducted to simplify the existing separation and solidification process of rare earth nuclides in LiCl-KCl eutectic waste salt from the pyroprocessing of spent nuclear fuel. More than 98wt% of Nd in LiCl-KCl eutectic salt was captured when the mass ratio of the composite was 0.67 over NdCl3 in the eutectic salt. The content of Nd{sub 2}O{sub 3} in the Nd captured-composite reached about 50wt%, and this composite was directly fabricated into a homogeneous and chemical resistant glass waste in a monolithic form. These results will be utilized in designing a process to simplify the existing separation and solidification process.

  8. 17O solid-state NMR spectroscopy of A2B2O7 oxides: quantitative isotopic enrichment and spectral acquisition?

    Science.gov (United States)

    Fernandes, Arantxa; Moran, Robert F; Sneddon, Scott; Dawson, Daniel M; McKay, David; Bignami, Giulia P M; Blanc, Frédéric; Whittle, Karl R; Ashbrook, Sharon E

    2018-02-13

    The potential of 17 O NMR spectroscopy for the investigation of A 2 B 2 O 7 ceramic oxides important in the encapsulation of radioactive waste is demonstrated, with post-synthetic enrichment by exchange with 17 O 2 gas. For Y 2 Sn 2 O 7 , Y 2 Ti 2 O 7 and La 2 Sn 2 O 7 pyrochlores, enrichment of the two distinct O species is clearly non quantitative at lower temperatures (∼700 °C and below) and at shorter times, despite these being used in prior work, with preferential enrichment of OA 2 B 2 favoured over that of OA 4 . At higher temperatures, the 17 O NMR spectra suggest that quantitative enrichment has been achieved, but the integrated signal intensities do not reflect the crystallographic 1 : 6 (O1 : O2) ratio until corrected for differences in T 1 relaxation rates and, more importantly, the contribution of the satellite transitions. 17 O NMR spectra of Y 2 Zr 2 O 7 and Y 2 Hf 2 O 7 defect fluorites showed little difference with any variation in enrichment temperature or time, although an increase in the absolute level of enrichment (up to ∼7.5%) was observed at higher temperature. DFT calculations show that the six distinct resonances observed cannot be assigned unambiguously, as each has contributions from more than one of the five possible next nearest neighbour environments. For La 2 Ti 2 O 7 , which adopts a layered perovskite-like structure, little difference in the spectral intensities is observed with enrichment time or temperature, although the highest absolute levels of enrichment (∼13%) were obtained at higher temperature. This work demonstrates that 17 O NMR has the potential to be a powerful probe of local structure and disorder in oxides, but that considerable care must be taken both in choosing the conditions for 17 O enrichment and the experimental acquisition parameters if the necessary quantitative measurements are to be obtained for more complex systems.

  9. Relaxation of the electronic states at a thin-layer YBa2Cu 3O7/PrBa2Cu3O7 interface

    KAUST Repository

    Gó mez, Javier Alexandra M; Larkin, Ivan A.; Schwingenschlö gl, Udo

    2010-01-01

    We discuss in detail spin-polarized electronic structure calculations for the 1 × 1 YBa2Cu3O7/PrBa 2Cu3O7 superlattice. Our results are based on the full-potential linear augmented plane wave method and the generalized gradient approximation for the exchange-correlation functional. The on-site Coulomb interaction affecting the correlated Cu 3d and Pr 4f electrons is taken into consideration. At first glance the YBa2Cu3O 7/PrBa2Cu3O7 interface appears to be inert, i.e., the electronic states do not show a clear sign of interaction between the two component materials. Nonetheless, a total energy analysis points to a significant modification of the magnetic coupling in the vicinity of the interface due to the relaxation of the electronic structure. © 2010 Elsevier B.V. All rights reserved.

  10. Relaxation of the electronic states at a thin-layer YBa2Cu 3O7/PrBa2Cu3O7 interface

    KAUST Repository

    Gómez, Javier Alexandra M

    2010-11-01

    We discuss in detail spin-polarized electronic structure calculations for the 1 × 1 YBa2Cu3O7/PrBa 2Cu3O7 superlattice. Our results are based on the full-potential linear augmented plane wave method and the generalized gradient approximation for the exchange-correlation functional. The on-site Coulomb interaction affecting the correlated Cu 3d and Pr 4f electrons is taken into consideration. At first glance the YBa2Cu3O 7/PrBa2Cu3O7 interface appears to be inert, i.e., the electronic states do not show a clear sign of interaction between the two component materials. Nonetheless, a total energy analysis points to a significant modification of the magnetic coupling in the vicinity of the interface due to the relaxation of the electronic structure. © 2010 Elsevier B.V. All rights reserved.

  11. Variscite (AlPO4 2H2O from Cioclovina Cave (Sureanu Mountains, Romania: a tale of a missing phosphate

    Directory of Open Access Journals (Sweden)

    Bogdan P. Onac

    2004-04-01

    Full Text Available Recent investigations on a phosphatized sediment sequence in the Cioclovina Cave led to the identification of a second occurrence in Romania (first time in the cave environment of variscite, AlPO4·2H2O. The mineral exists as dull-white, tiny crusts and veinlets within the thick argillaceous material accumulated on the cave floor. Under scanning electron microscope (SEM variscite appears as subhedral to euhedral micron-size crystals. The {111} pseudo-octahedral form is rather common. Variscite was further characterized by means of X-ray diffraction, thermal, vibrational FT-IR and FT-Raman spectroscopy, and by SEM energy-dispersive spectrometry (EDS. The calculated orthorhombic cell parameters are a = 9.823(4, b = 8.562(9, c = 9.620(5 Å, and V = 809.167(6 Å3. The ED spectrum of variscite shows well-resolved Al and P lines confirming thus the presence of the major elements in our compound. The formation of variscite is attributed to the reaction between the phosphate-rich leachates derived from guano and the underlying clay sediments.

  12. SiO2 and ZnO dopants in three-dimensionally printed tricalcium phosphate bone tissue engineering scaffolds enhance osteogenesis and angiogenesis in vivo.

    Science.gov (United States)

    Fielding, Gary; Bose, Susmita

    2013-11-01

    Calcium phosphate (CaP) scaffolds with three-dimensionally-interconnected pores play an important role in mechanical interlocking and biological fixation in bone implant applications. CaPs alone, however, are only osteoconductive (able to guide bone growth). Much attention has been given to the incorporation of biologics and pharmacologics to add osteoinductive (able to cause new bone growth) properties to CaP materials. Because biologics and pharmacologics are generally delicate compounds and also subject to increased regulatory scrutiny, there is a need to investigate alternative methods to introduce osteoinductivity to CaP materials. In this study silica (SiO2) and zinc oxide (ZnO) have been incorporated into three-dimensional printed β-tricalcium phosphate (β-TCP) scaffolds to investigate their potential to trigger osteoinduction in vivo. Silicon and zinc are trace elements that are common in bone and have also been shown to have many beneficial properties, from increased bone regeneration to angiogenesis. Implants were placed in bicortical femur defects introduced to a murine model for up to 16 weeks. The addition of dopants into TCP increased the capacity for new early bone formation by modulating collagen I production and osteocalcin production. Neovascularization was found to be up to three times more than the pure TCP control group. The findings from this study indicate that the combination of SiO2 and ZnO dopants in TCP may be a viable alternative to introducing osteoinductive properties to CaPs. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  13. Structural change of NaO1/2-WO3-NbO5/2-LaO3/2-PO5/2 glass induced by electrochemical substitution of sodium ions with protons.

    Science.gov (United States)

    Ishiyama, Tomohiro; Yamaguchi, Takuya; Nishii, Junji; Yamashita, Toshiharu; Kawazoe, Hiroshi; Kuwata, Naoaki; Kawamura, Junichi; Omata, Takahisa

    2015-05-28

    Structural changes of 35NaO1/2-1WO3-8NbO5/2-5LaO3/2-51PO5/2 glass (1W-glass) before and after the electrochemical substitution of sodium ions with protons by alkali-proton substitution (APS) are studied by Raman and (31)P magic-angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopies. The glass before APS consists of (PO3(-))8.6(P2O7(4-)) chains on average and the terminal Q(1) units (-O-PO3(3-)) are bound to MO6 octahedra (M denotes niobium or tungsten) through P-O-M bonds. Some non-bridging oxygens (NBOs) in the MO6 octahedra are present in addition to the bridging oxygens (BOs) in P-O-M bonds. APS induces fragmentation of the phosphate chains because the average chain length decreases to (PO3(-))3.7(P2O7(4-)) after APS, despite the total number of modifier cations of sodium and lanthanum ions and protons being unaffected by APS. This fragmentation is induced by some of the NBOs in the MO6 octahedra before APS, changing to BOs of the newly formed M-O-P bonds after APS, because of the preferential formation of P-OH bonds over M-OH ones in the present glass. We show that APS under the conditions used here is not a simple substitution of sodium ions with protons, but it is accompanied by the structural relaxation of the glass to stabilize the injected protons.

  14. Thermal Stability and Proton Conductivity of Rare Earth Orthophosphate Hydrates

    DEFF Research Database (Denmark)

    Anfimova, Tatiana; Li, Qingfeng; Jensen, Jens Oluf

    2014-01-01

    as the rhabdophane structure is preserved. The bound hydrate water is accommodated in the rhabdophane structure and is stable at temperatures of up to 650 oC. The thermal stability of the hydrate water and the phosphate structure are of significance for the proton conductivity. The LaPO4·0.6H2O and NdPO4•0.5H2O......Hydrated orthophosphate powders of three rare earth metals, lanthanum, neodymium and gadolinium, were prepared and studied as potential proton conducting materials for intermediate temperature electrochemical applications. The phosphates undergo a transformation from the rhabdophane structure...... to the monazite structure upon dehydration. The thermal stability of the hydrate is studied and found to contain water of two types, physically adsorbed and structurally bound hydrate water. The adsorbed water is correlated to the specific surface area and can be reversibly recovered when dehydrated as long...

  15. Plasma treatment for influence of cold in different phases of formation of calcium phosphate on the surface of nanocomposite Al{sub 2}O{sub 3}/ZrO{sub 2}; Influencia do tratamento por plasma a frio na formacao de diferentes fases de fosfatos de calcio sobre a superficie do nanocomposito de Al{sub 2}O{sub 3}/ZrO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Santos, K.H.; Ferreira, J.A.; Osiro, D.; Nascimento, L.I.S.; Pallone, E.M.J.A., E-mail: katiahsantos@usp.br [Universidade de Sao Paulo (FZEA/USP), Pirassununga, SP (Brazil). Faculdade de Zootecnia e Engenharia de Alimentos; Colnago, L.B. [Embrapa Instrumentacao, Sao Carlos, SP (Brazil); Alves Junior, C. [Universidade Federal Rural do Semi-Arido (UFERSA),Mossoro, RN (Brazil)

    2016-07-01

    Among the different techniques used in surface treatment of biomaterials, the plasma has been noted for its ability to promote changes in surface roughness of the treated material. The objective of this study was to evaluate the influence of treatment by plasma in the formation of calcium phosphate nanocomposite on the surface of Al2O3/ZrO2 (5% by vol.). For this, samples were formed, calcined, sintered, surface treated and coated biomimeticamente plasma for 14 days. The surface characterization was performed by confocal microscopy and spectroscopy, Fourier transform infrared (FTIR). After coating, the samples were characterized by FTIR and X-ray diffraction X-ray (XRD). It was observed that the treatments improved surface roughness. Furthermore, regardless of the surface treatment were observed only three phases of calcium phosphates: HA α -TCP and -β-TCP. It is worth noting that depending on the composition, there are variations in the amount of phosphates, as well as the percentages of the different phases. (author)

  16. X-ray characteristics and thermal transformations of double diphosphates MLnP2O7 (M-K, Rb, Cs; Ln-REE of yttrium subgroup)

    International Nuclear Information System (INIS)

    Anisimova, N.Yu.; Chudinova, N.N.; Trunov, V.K.; AN SSSR, Moscow

    1993-01-01

    Results on studying double diphosphates of rare earth metals with K, Rb and Cs are studied by methods of X-ray analysis, high-temperature roentgenography and DTA. Double diphosphates of rare earth and alkali metals are crystallized in three structural types: monoclinic, rhombic and hexagonal, whereby rhombic form by heating inversely transforms into hexagonal one. MLnP 2 O 7 thermal transformations are studied

  17. A bona fide two-dimensional percolation model: an insight into the optimum photoactivator concentration in La2/3-xEuxTa2O7 nanosheets

    Directory of Open Access Journals (Sweden)

    Tadashi C Ozawa, Katsutoshi Fukuda, Yasuo Ebina, Kosuke Kosuda, Akira Sato, Yuichi Michiue, Keiji Kurashima and Takayoshi Sasaki

    2011-01-01

    Full Text Available La–Eu solid solution nanosheets La2/3−xEuxTa2O7 have been synthesized, and their photoluminescence properties have been investigated. La2/3−xEuxTa2O7 nanosheets were prepared from layered perovskite compounds Li2La2/3−xEuxTa2O7 as the precursors by soft chemical exfoliation reactions. Both the precursors and the exfoliated nanosheets exhibit a decrease in intralayer lattice parameters as the Eu contents increase. However, there is a discontinuity in this trend between the nominal Eu content ranges x≤ 0.3 and x ≥ 0.4. This discontinuity is attributed to the difference in degree of TaO6 octahedra tilting for the La- and Eu-rich phases. La2/3−xEuxTa2O7 nanosheets exhibit red emission, characteristic of the f–f transitions in Eu3+ photoactivators. The photoluminescence emission can be obtained from both host and direct photoactivator excitation. However, photoluminescence emission through host excitation is much more dominant than that through direct photoactivator excitation, and this behavior is consistent with that of all the other rare-earth photoactivated nanosheets reported previously. The absolute photoluminescence quantum efficiency of the La2/3−xEuxTa2O7 nanosheets increases as the experimentally determined Eu contents increase up to x=0.45 and decrease above it. This result is in good agreement with the optimum photoactivator concentration expected from the percolation theory. These solid solution La2/3−xEuxTa2O7 nanosheets are excellent models for validating the theory of optimum photoactivator concentration in the truly two-dimensional photoactivator matrix.

  18. Activation analysis of rare-earth elements in opium and cannabis samples

    International Nuclear Information System (INIS)

    Henke, G.

    1977-01-01

    Rare-earth concentrations in 65 Opium, Cannabis and Cannabis resin samples seized from various parts of the world were determined by destructive NAA. Because of the greater concentrations of Ca, P, K, Fe, Na and Si in plant materials, rare-earth elements were isolated after neutron irradiation and determined by gamma-spectrometry. The main steps of the method are: Preashing of 1 g Cannabis resin, 2.5 g Cannabis or 7.5 g Opium, respectively, in quartz ampoules (5 h, 500 deg C). Neutron irradiation, 24 h at 5x10 13 n cm -2 sec -1 . Cooling period 2-3 days. After addition of 0.1 μCi 139 Ce and rare-earth carriers wet ashing of irradiated samples with H 2 SO 4 /HNO 3 , followed by alternate addition of HNO 3 and H 2 O 2 (30%). Precipitation and removal of silicates, precipitation of fluorides, precipitation of hydroxides. Dissolution of hydroxides in HCl. Extraction with di-(2-ethylhexyl)phosphate (DEHP)/toluene and twice back-extraction of rare earths, gamma-spectrometry of HCl phase. Due to sample activity and half-life of nuclides, three measurements were made on each sample: 2 days (for La, Sm, Gd, Ho, Er, Yb); 14 days (for Nd, Lu) and 30 days after irradiation (for Ce, Eu, Tb). Great variations in absolute element concentrations, but only small significant differences of rare earth concentration ratios were found, indicating inconsiderable biogeochemical fractionation. The mean values of these ratios correspond to the relative abundances of the rare earths in the upper continental earth's crust. (T.G.)

  19. Nonlinear optical characterization of phosphate glasses based on ZnO using the Z-scan technique

    International Nuclear Information System (INIS)

    Mojdehi Masoumeh Shokati; Yunus Wan Mahmood Mat; Talib Zainal Abidin; Tamchek, N.; Fhan Khor Shing

    2013-01-01

    The nonlinear optical properties of a phosphate vitreous system [(ZnO) x − (MgO) 30−x − (P 2 O 5 ) 70 ], where x = 8, 10, 15, 18, and 20 mol% synthesized through the melt-quenching technique have been investigated by using the Z-scan technique. In the experiment, a continuous-wave laser with a wavelength of 405 nm was utilized to determine the sign and value of the nonlinear refractive (NLR) index and the absorption coefficient with closed and opened apertures of the Z-scan setup. The NLR index was found to increase with the ZnO concentration in the glass samples by an order of 10 −10 cm 2 ·W −1 . The real and imaginary parts of the third-order nonlinear susceptibility were calculated by referring to the NLR index (n 2 ) and absorption coefficient (β) of the samples. The value of the third-order nonlinear susceptibility was presented by nonlinear refractive or absorptive behavior of phosphate glasses for proper utilization in nonlinear optical devices. Based on the measurement, the positive sign of the NLR index shows a self-focusing phenomenon. The figures of merit for each sample were calculated to judge the potential of phosphate glasses for application in optical switching

  20. High magnetic field study of HoBaCo2O5.5 and GdBaCo2O5.5 layered cobaltites: the effect of rare-earth size

    International Nuclear Information System (INIS)

    Frontera, C.; Respaud, M.; Garcia-Munoz, J.L.; Llobet, A.; Carrillo, A.E.; Caneiro, A.; Broto, J.M.

    2004-01-01

    By means of high-pulsed magnetic field up to μ 0 H=32 T we have studied HoBaCo 2 O 5+δ (δ=0.52(1)). The high-field M(H) integrated curves evidence a magnetic field-induced phase transition visible from about T=75 to 275 K. The obtained results are compared with the field-induced transition found for GdBaCo 2 O 5+δ (with δ=0.54(2)). The jump of the magnetization at the field-induced transition is independent of the rare earth at this level of oxygen content. In contrast, we have observed larger values of the critical field, and that the transition persists up to higher temperature, when reducing the rare-earth size. This indicates that the low-temperature antiferromagnetic phase becomes more stable when the size of the rare earth is reduced

  1. Structural investigations on zirconium phosphate-phosphite and on its n-butylamine intercalate

    International Nuclear Information System (INIS)

    Rajeh, A.O.; Szirtes, L.

    1995-01-01

    Zirconium phosphate-phosphite have various structure belonging to the drying heat of the sample. While sample dried above sat. NaCl solution had interlayer distance of 1.30 nm (result from d 1 =0.74 nm and d 2 =0.56 nm for phosphite layer), the sample dried under IR lamp on air having interlayer spacing d=0.74 nm charactderistic for α-Zr(HPO 4 ) 2 H 2 O containing little amount of phosphite groups. The compositions of the first sample can be characterized by chemical formula, as Zr(HPO 4 ) 0 .7 (HPO 3 ) 1.3 0.5H 2 O. The X-ray powder diffraction data of n-butylamine intercalate suggest that in the process take place only the phosphate ,region of zirconium phosphate-phosphite (ZrPP). (author). 13 refs., 5 figs

  2. Electronic structure of PrBa2Cu3O7 within LSDA+U: Different self-consistent solutions

    Directory of Open Access Journals (Sweden)

    M R Mohammadizadeh

    2009-08-01

    Full Text Available  Based on the density functional theory and using the full-potential linearized augmented-plane-waves method the electronic structure of PrBa2Cu3O7 (Pr123 system was calculated. The rotationally invariant local spin density approximation plus Hubbard parameter U was employed for Pr(4f orbitals. One self-consistent solution more stable than the previous solution, which has been proposed by Liechtenstein and Mazin (LM, was found. In contrast to the LM solution, it can explain the results of the 17O NMR spectroscopy study of nonsuperconducting Pr123 samples. This new solution favors the suggestion that the pure Pr123 samples should be intrinsically superconductor and metal similar to the other RBa2Cu3O7 (R=Y or a rare earth element samples. The imperfections cause the superconducting holes are transferred to the nonsuperconducting hole states around the high-symmetry (π/a, π/b, kz line in the Brillouin zone and so, superconductivity is suppressed in the conventional samples. It predicts that the superconducting 2pσ holes in the O2 sites of nonsuperconducting Pr123 samples should be depleted and the ones in the O3 sites should be almost unchanged .

  3. Lar mountain phosphate ore processing using flotation approach

    International Nuclear Information System (INIS)

    Gharabaghi, M.; Noaparast, M.; Shafaei Tonkaboni, S. Z.

    2007-01-01

    The sample of Lar Mountain Phosphate deposit which is located in the southwest of Iran, was studied to upgrade its phosphate grade. The results obtained from mineralogical studies showed the presence of apatite, CaO, Al 2 O 3 , Fe 2 O 3 and SiO 2 , in which carbonate was detected as the main gangue. Two sets of direct and reverse flotation tests were performed using samples from this deposit with 10% P 2 O 5 . In phosphate flotation (direct approach), the samples were conditioned with sodium silica, oleic acid-fuel oil and Armac T-fuel oil. The direct flotation at pH=9.2 yielded a product with 23.2% of P 2 O 5 and 75.16% recovery. The reverse flotation tests were carried out at pH=5.2, with floating carbonate and pulp de-oiling, using H 2 SO 4 and wash water, and phosphate was then floated from siliceous gangue. In the second sets of the reverse approach, depressing the phosphate and floating silica with Amines in natural pH were done. However the best concentrate assay was 31.2% P 2 O 5 with a 71.12% recovery, which was obtained from reverse tests

  4. High temperature oxidation and crystallization behavior of phosphate glass compositions

    International Nuclear Information System (INIS)

    Russo, Diego; Rodriguez, Diego; Grumbaum, N.; Gonzalez Oliver, Carlos

    2003-01-01

    We analyzed the thermal transformation of three iron phosphate glasses having the following nominal compositions: M4 [70% P 2 O 5 , 30% Fe 2 O 3 ], M5 [85% M4, 15% UO 2 ] y M7 [69.7% P 2 O 5 , 28.6% Fe 2 O 3 , 1,7% Al 2 O 3 ]. Thermogravimetric analysis, DTA (differential thermal analysis) and SAXS (Small Angle X-ray Scattering) were performed.It was observed that it is easily possible to produce glasses in these systems having very low crystallinity.We could determine the final stable crystalline phases [Fe 4 (P 2 O 7 ) 3 , Fe(PO 3 ) 3 and Fe 3 (P 2 O 7 ) 2 ].The presence of uranium ions affects not only the redox effects but also the crystallization of the system.SAXS data obtained during the heating in vacuum up to ∼600degC, gave some variation of scattering intensities vs. scattering vector suggesting the development of an extra phase or some kind inhomogeneities that seems to disappear on heating

  5. Preparation and Characterization of Porous Calcium Phosphate Bioceramics

    Institute of Scientific and Technical Information of China (English)

    Honglian Dai; Xinyu Wang; Yinchao Han; Xin Jiang; Shipu Li

    2011-01-01

    β-tricalcium phosphate (β-TCP) powder and Na2O-CaO-MgO-P2O5 glass binder were synthesized and mixed, and then the biodegradable porous calcium phosphate ceramics were successfully prepared by foaming and sintering at 850℃. The as-prepared ceramics possess a high porosity with partial three-dimension interconnected macro- and micro-pores. As in vitro experiment testified, the calcium phosphate ceramics (CPCs) has good degradability.

  6. New studies on the synthesis and structural chemistry of polynary lithium and silver transition metal phosphates

    International Nuclear Information System (INIS)

    Mosymow, Emma

    2015-01-01

    In the course of this work extensive equilibrium studies were carried out in the four-system systems Li / M / P / O (M: Cr, Mn) in the search for new, powerful cathode materials for lithium ion batteries. The phosphates LiCr II 4 (PO 4 ) 3 , NaCr II 4 (PO 4 ) 3 , Li 5 Cr II 2 Cr III (PO 4 ) 4 , monoclines Li 3 Cr 2 (PO 4 ) 3 , Cr II 5 Cr III 2 (P 2 O 7 ) 4 and LiMn II 2 P 3 O 10 were obtained for the first time. The present work reports on their synthesis, crystallographic characterization and their spectroscopic and magnetic properties. The equilibrium studies in the Li / Cr / P / O system led to the elucidation of numerous phase relationships. For example, the coexistence regions LiCr 4 (PO 4 ) 3 / Li 5 Cr 3 (PO 4 ) 4 / Cr 2 O 3 / CrP and Li 9 Cr 3 (PO 4 ) 3 / LiCrP 2 O 7 / CrP. The coexistence of some equilibrium phases such as lithium orthophosphate and lithium manganese(II) orthophosphate as well as lithium metaphosphate and manganese(III) metaphosphate were also investigated in the Li / Mn / P / O system. Furthermore, the de-intercalation behavior of silver manganese phosphates was investigated with the possibility of demonstrating metastable phosphates with manganese in oxidation states higher than 3+. In this case the four-substance system Ag / Mn / P / O with Mn(II) and Mn(III) was considered. The reaction conditions were adapted to those of the experiments in the corresponding lithium-containing systems. Within the scope of the equilibrium studies two new pyrophosphates AgMnP 2 O 7 and Ag 1,6 Mn 3 (P 2 O 7 ) 2 were found and characterized. [de

  7. Calcium phosphate glass-ceramics for bioactive coating on a β-titanium alloy

    International Nuclear Information System (INIS)

    Kasuga, T.; Nogami, M.; Niinomi, M.

    2003-01-01

    The formation of a porous coating is the decisive feature for the bio-compatibility of silica-free calcium phosphate glass ceramics on alloy surfaces like the β-Ti structured Ti-29Nb-13Ta-4.6Zr used in this work. The ceramic composition is highly important: 50CaO-40P 2 O 5 -7Na 2 O-3TiO 2 glass powder produces a pore-free coating unable to bind hydroxyapatite, whereas 60CaO-30P 2 O 5 -7Na 2 O-3TiO 2 glass incorporates pores from which a crystalline hydroxyapatite phase can grow over the surface from simulated body fluid (see Figure). (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  8. Iron phosphate glasses: Bulk properties and atomic scale structure

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Kitheri; Stennett, Martin C.; Hyatt, Neil C.; Asuvathraman, R.; Dube, Charu L.; Gandy, Amy S.; Govindan Kutty, K. V.; Jolley, Kenny; Vasudeva Rao, P. R.; Smith, Roger

    2017-10-01

    Bulk properties such as glass transition temperature, density and thermal expansion of iron phosphate glass compositions, with replacement of Cs by Ba, are investigated as a surrogate for the transmutation of 137Cs to 137Ba, relevant to the immobilisation of Cs in glass. These studies are required to establish the appropriate incorporation rate of 137Cs in iron phosphate glass. Density and glass transition temperature increases with the addition of BaO indicating the shrinkage and reticulation of the iron phosphate glass network. The average thermal expansion coefficient reduces from 19.8 × 10-6 K-1 to 13.4 × 10-6 K-1, when 25 wt. % of Cs2O was replaced by 25 wt. % of BaO in caesium loaded iron phosphate glass. In addition to the above bulk properties, the role of Ba as a network modifier in the structure of iron phosphate glass is examined using various spectroscopic techniques. The FeII content and average coordination number of iron in the glass network was estimated using Mössbauer spectroscopy. The FeII content in the un-doped iron phosphate glass and barium doped iron phosphate glasses was 20, 21 and 22 ± 1% respectively and the average Fe coordination varied from 5.3 ± 0.2 to 5.7 ± 0.2 with increasing Ba content. The atomic scale structure was further probed by Fe K-edge X-ray absorption spectroscopy. The average coordination number provided by extended X-ray absorption fine structure spectroscopy and X-ray absorption near edge structure was in good agreement with that given by the Mössbauer data.

  9. RE{sub 2}B{sub 8}O{sub 15} (RE = La, Pr, Nd). Syntheses of three new rare earth borates isotypic to Ce{sub 2}B{sub 8}O{sub 15}

    Energy Technology Data Exchange (ETDEWEB)

    Glaetzle, Matthias; Hoerder, Gregor J.; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie

    2016-08-01

    The rare earth borates RE{sub 2}B{sub 8}O{sub 15} (RE = La, Pr, Nd) were synthesized in a Walker-type multianvil apparatus under conditions of 5.5 GPa and 1100 C. Starting from the corresponding rare earth oxides and boron oxide, the syntheses yielded crystalline products of all new compounds that allowed crystal structure analyses based on single-crystal X-ray diffraction data for La{sub 2}B{sub 8}O{sub 15} and Nd{sub 2}B{sub 8}O{sub 15}. The compound Pr{sub 2}B{sub 8}O{sub 15} could be characterized via X-ray powder diffractometry. The results show that the new compounds crystallize isotypically to Ce{sub 2}B{sub 8}O{sub 15} in the monoclinic space group P2/c. The infrared spectra of RE{sub 2}B{sub 8}O{sub 15} (RE = La, Pr, Nd) have also been studied.

  10. Superconducting properties of modified YBa2Cu3O7-δ ceramics

    International Nuclear Information System (INIS)

    Kaleva, G.M.; Politova, E.D.; Kudinova, M.V.; Prutchenko, S.G.; Venevtsev, Yu.N.

    1993-01-01

    In connection with the promising practical applications of high temperature superconductors (HTSC) particular attention has been paid to studying the influence of dopant elements on the properties of HTSC ceramics. According to earlier work, replacement of the yttrium in the compound YBa 2 Cu 3 O 7-8 (1-2-3) by rare earth elements, excluding Ce, Pr, Tb, and Pm, has almost no influence on the superconducting transition temperature (T c ∼ 90 K). Of the alkaline metals, only Sr will displace Ba over a wide range of concentrations (up to 50 at %), but in this case T c is reduced to 86 K. The strongest influence on the superconducting properties results from replacement of copper by 3d transition metals. Introduction of 10 at.% Zn, Co, Fe, Ni, Ti, Mn, or Cr in place of the copper leads to a drastic lowering of T c . At the same time it has been reported that microadditions of individual elements (replacement of Cu by Pd, Ti, and Fe, at a level of 0.1-0.5 at.%,) may elevate conducting phase and improve the contacts between grains, so that, in particular, there is an increase in the critical current density. In view of the possible positive influence which introduction of small quantities of individual elements may have 1-2-3 compounds, in the present work, the authors have studied the action of dopant additions, including complex ones, on this phase, with the goal of improving its superconducting properties. Structural and superconducting properties were studied for samples of YBa 2 (Cu 1- x M x ) 3 O 7-δ , with M = Sb (I), Mn (II), and Sb 1/2 Mn 1/2 (III), and (1-x)Y 1/3 Ba 2/3 CuO 3-δ ·xSr(Sb 1/2 Mn 1/2 )O 3 (IV), using x-ray diffraction, electron microscopy, Mossbauer spectroscopy, as well as changes in the temperature dependence of the resistivity ρ(T)

  11. Electronic parameters of Sr2Nb2O7 and chemical bonding

    DEFF Research Database (Denmark)

    Atuchin, V.V.; Grivel, Jean-Claude; Korotkov, A.S.

    2008-01-01

    /2)) and Delta(O-Sr) = BE(O 1s)-BE(Sr 3d(5/2)), were used to characterize the valence electron transfer on the formation of the Nb-O and Sr-O bonds. The chemical bonding effects were considered on the basis of our XPS results for Sr2Nb2O7 and earlier published structural and XPS data for other Sr- or Nb...

  12. Nonlinear acoustic properties of the ternary (La sub 2 O sub 3) sub x (Sm sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) phosphate glasses

    International Nuclear Information System (INIS)

    Senin, H.B.; Sidek, H.A.A.; Saunders, G.A.

    1994-01-01

    From measurements of changes in transit time of 10 MHz of ultrasonic wave as a function of temperature and hydrostatic pressure, the linear and non-linear acoustic properties of the ternary (La sub 2 O sub 3) sub x (Sm sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses with compositions near to that corresponding to the metaphosphate have been determined. For each glass the second order elastic stiffness tensor components C sub ijs (SOEC) continue to increase down to 10K in a manner consistent with phonons interactions with two level systems. Measurements of the effects of hydrostatic pressure on the ultrasonic wave velocities have been used to determine the hydrostatic pressure derivatives (dC sub ij/dP) sub T,P=0 of the SOEC and (dB0 sup s)/dP) sub T,P=0 of the bulk modulus B0 sup s at room temperature (293K). For the ternary (La sub 2 O sub 3) sub x (Sm sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses, (dC sub 11/dP), (dC sub 44/dP), and (dBo/dP), are small but positives; these glasses stiffen under pressure. The elastic behaviour of these ternary glasses lies intermediate between those of (Sm sub 2 O sub 3)(P sub 2 O sub 5) sub (1-x) and (La sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses. Replacement of the Sm sup 3+ by La sup 3+ in the ternary phosphate glasses negates the acoustic mode softening. Possible sources of the different effects of La sub 3+ and Sm sub 3+ modifiers on the nonlinear acoustic properties of metaphosphate glasses are discussed

  13. A study on artificial rare earth (RE2O3) based neutron absorber

    International Nuclear Information System (INIS)

    KIM, Kyung-O; Kyung KIM, Jong

    2015-01-01

    A new concept of a neutron absorption material (i.e., an artificial rare earth compound) was introduced for criticality control in a spent fuel storage system. In particular, spent nuclear fuels were considered as a potential source of rare earth elements because the nuclear fission of uranium produces a full range of nuclides. It was also found that an artificial rare earth compound (RE 2 O 3 ) as a High-Level Waste (HLW) was naturally extracted from pyroprocessing technology developed for recovering uranium and transuranic elements (TRU) from spent fuels. In this study, various characteristics (e.g., activity, neutron absorption cross-section) were analyzed for validating the application possibility of this waste compound as a neutron absorption material. As a result, the artificial rare earth compound had a higher neutron absorption probability in the entire energy range, and it can be used for maintaining sub-criticality for more than 40 years on the basis of the neutron absorption capability of Boral™. Therefore, this approach is expected to vastly improve the efficiency of radioactive waste management by simultaneously keeping HLW and spent nuclear fuel in a restricted space. - Highlights: • Quantitative analysis of rare earth elements in PWR spent fuels. • Extraction of artificial rare earth compound using pyroprocessing technology. • Characteristic analysis of artificial rare earth elements. • Performance evaluation of artificial rare earth for criticality control.

  14. Novel selenium containing boro-phosphate glasses: Preparation and structural study

    Energy Technology Data Exchange (ETDEWEB)

    Ciceo-Lucacel, R.; Radu, T., E-mail: teodora.radu@phys.ubbcluj.ro; Ponta, O.; Simon, V.

    2014-06-01

    We synthesized a new boro-phosphate glass system with different %mol SeO{sub 2} content by conventional melt quenching technique. All samples were obtained in a glassy state with the vitreous structure confirmed by X-ray diffraction analysis. Scanning electron microscopy (SEM) revealed some non-homogeneous domains on the glasses surface, and their tendency to link each other once the selenium oxide content increases. Energy-dispersive X-ray analysis (EDAX) indicated similar elemental composition in different regions of each sample. X-ray photoelectron spectroscopy (XPS) was used to determine the nature of chemical bonding and the elemental composition at the sample surfaces, and Fourier transform infrared (FT-IR) spectroscopy was used to determine the structural groups in the obtained glass structure. Based on FT-IR results, the glass structure at short range order consists mainly of small phosphate units such as pyrophosphate (i.e. P{sub 2}O{sub 7}{sup 4−} dimmers or terminating groups at the end of phosphate chains) and some metaphosphate (i.e. PO{sub 3}{sup −} middle groups in the phosphate chains) units. The boron atoms are mainly placed in three-coordinated sites in BØ{sub 3} or BØ{sub 2}O{sup −} units. A small contribution of BØ{sub 4}{sup −} units was also detected from the FT-IR spectra of glasses. For SeO{sub 2} content higher than 5 mol%, the modifier role of selenium ions is strongly reflected on the local structure dominated in this case by pyrophosphate units. - Highlights: • New P{sub 2}O{sub 5}-CaO-B{sub 2}O{sub 3}-SeO{sub 2} glasses synthesized by conventional melt quenching method. • Evidences for the Se ions modifier role in the local structure by FT-IR and XPS. • Significant advances in understanding the structural properties of the new system.

  15. Novel selenium containing boro-phosphate glasses: Preparation and structural study

    International Nuclear Information System (INIS)

    Ciceo-Lucacel, R.; Radu, T.; Ponta, O.; Simon, V.

    2014-01-01

    We synthesized a new boro-phosphate glass system with different %mol SeO 2 content by conventional melt quenching technique. All samples were obtained in a glassy state with the vitreous structure confirmed by X-ray diffraction analysis. Scanning electron microscopy (SEM) revealed some non-homogeneous domains on the glasses surface, and their tendency to link each other once the selenium oxide content increases. Energy-dispersive X-ray analysis (EDAX) indicated similar elemental composition in different regions of each sample. X-ray photoelectron spectroscopy (XPS) was used to determine the nature of chemical bonding and the elemental composition at the sample surfaces, and Fourier transform infrared (FT-IR) spectroscopy was used to determine the structural groups in the obtained glass structure. Based on FT-IR results, the glass structure at short range order consists mainly of small phosphate units such as pyrophosphate (i.e. P 2 O 7 4− dimmers or terminating groups at the end of phosphate chains) and some metaphosphate (i.e. PO 3 − middle groups in the phosphate chains) units. The boron atoms are mainly placed in three-coordinated sites in BØ 3 or BØ 2 O − units. A small contribution of BØ 4 − units was also detected from the FT-IR spectra of glasses. For SeO 2 content higher than 5 mol%, the modifier role of selenium ions is strongly reflected on the local structure dominated in this case by pyrophosphate units. - Highlights: • New P 2 O 5 -CaO-B 2 O 3 -SeO 2 glasses synthesized by conventional melt quenching method. • Evidences for the Se ions modifier role in the local structure by FT-IR and XPS. • Significant advances in understanding the structural properties of the new system

  16. Optical spectroscopy of rare earth ion-doped TiO2 nanophosphors.

    Science.gov (United States)

    Chen, Xueyuan; Luo, Wenqin

    2010-03-01

    Trivalent rare-earth (RE3+) ion-doped TiO2 nanophosphors belong to one kind of novel optical materials and have attracted increasing attention. The luminescence properties of different RE3+ ions in various TiO2 nanomaterials have been reviewed. Much attention is paid to our recent progresses on the luminescence properties of RE3+ (RE = Eu, Er, Sm, Nd) ions in anatase TiO2 nanoparticles prepared by a sol-gel-solvothermal method. Using Eu3+ as a sensitive optical probe, three significantly different luminescence centers of Eu3+ in TiO2 nanoparticles were detected by means of site-selective spectroscopy at 10 K. Based on the crystal-field (CF) splitting of Eu3+ at each site, C2v and D2 symmetries were proposed for Eu3+ incorporated at two lattice sites. A structural model for the formation of multiple sites was proposed based on the optical behaviors of Eu3+ at different sites. Similar multi-site luminescence was observed in Sm(3+)- or Nd(3+)-doped TiO2 nanoparticles. In Eu(3+)-doped TiO2 nanoparticles, only weak energy transfer from the TiO2 host to the Eu3+ ions was observed at 10 K due to the mismatch of energy between the TiO2 band-gap and the Eu3+ excited states. On the contrary, efficient host-sensitized luminescences were realized in Sm(3+)- or Nd(3+)-doped anatase TiO2 nanoparticles due to the match of energy between TiO2 band-gap and the Sm3+ and Nd3+ excited states. The excitation spectra of both Sm(3+)- and Nd(3+)-doped samples exhibit a dominant broad peak centered at approximately 340 nm, which is associated with the band-gap of TiO2, indicating that sensitized emission is much more efficient than direct excitation of the Sm3+ and Nd3+ ions. Single lattice site emission of Er3+ in TiO2 nanocrystals can be achieved by modifying the experimental conditions. Upon excitation by a Ti: sapphire laser at 978 nm, intense green upconverted luminescence was observed. The characteristic emission of Er3+ ions was obtained both in the ultraviolet-visible (UV-vis) and

  17. Biocompatibility studies of endothelial cells on a novel calcium phosphate/SiO2-xerogel composite for bone tissue engineering

    International Nuclear Information System (INIS)

    Thimm, Benjamin W; Unger, Ronald E; Kirkpatrick, C James; Neumann, Hans-Georg

    2008-01-01

    The bone biomaterial BONITmatrix, a nanoporous, granular scaffold composed of hydroxylapatite, calcium phosphate and SiO 2 , linked by a dense collagen mesh, was tested for its biocompatibility using endothelial cells (EC) in the form of macrovascular HUVEC, microvascular HDMEC and the endothelial cell line ISOHAS-1. Cells were examined for their adherence and growth on the biomaterial and this was followed by confocal laser scanning microscopy after vital staining or immunocytochemical reactions, as well as by scanning electron microscopy. Macro- and microvascular ECs predominantly spread on BONITmatrix-collagen mesh-covered surfaces and fibres and maintained their typical morphology. As ECs in vivo must build up a functional vasculature, the seeded cells were further tested for proinflammatory expression markers and cytokine expression after lipopolysaccharide stimulation. Protein-coating studies revealed that BONITmatrix-collagen scaffolds needed human blood serum coating to successfully support the growth of ECs. All cells expressed endothelium-specific surface marker proteins such as PECAM-1, VE-cadherin and vWF. The in vitro data support recent in vivo studies and indicate that this calcium phosphate/SiO 2 -xerogel composite could be a useful scaffold material for tissue engineering

  18. Collisional Removal of OH (X (sup 2)Pi, nu=7) by O2, N2, CO2, and N2O

    Science.gov (United States)

    Knutsen, Karen; Dyer, Mark J.; Copeland, Richard A.

    1996-01-01

    Collisional removal rate constants for the OH (X 2PI, nu = 7) radical are measured for the colliders O2, CO2, and N2O, and an upper limit is established for N2. OH(nu = 4) molecules, generated in a microwave discharge flow cell by the reaction of hydrogen atoms with ozone, are excited to v = 7 by the output of a pulsed infrared laser via direct vibrational overtone excitation. The temporal evolution of the P = 7 population is probed as a function of the collider gas partial pressure by a time-delayed pulsed ultraviolet laser. Fluorescence from the B 21 + state is detected in the visible spectral region.

  19. Synthesis and ultrasonic characterisation of vitreous holmium phosphates

    International Nuclear Information System (INIS)

    Senin Hassan; Sidek Hj, Abdul Aziz; Abdul Halim Shaari

    1996-01-01

    The ultrasonic properties of holmium metaphosphate glasses (Ho sub 2 O sub 3) sub x (P sub 2 O sub 5) sub 1-x, with the mole fraction of x of holmium oxide equal to 0.208, 0.22 and 0.231 respectively, have been determined from measurements of the effects of temperature and hydrostatic pressure on ultrasonic wave velocities. At temperature below about 100K, the ultrasonic wave velocity of this type of rare earth phosphate glasses become anomalously dependent upon temperature; a behaviour associated with the interaction between acoustic phonons and two level systems. The hydrostatic pressure derivatives (∂ C sup S sub IJ / ∂ P) sub p=0 of the elastic stiffnesses C sub IJ and also (∂ C sup S sub IJ / ∂ P) sub p=0 of the bulk modulus B sup S of these glasses are anomalously negative. Both longitudinal γ sub L and shear γ sub S acoustic mode Gruneisen parameters are small and negative : the application of pressure softens the long-wavelength acoustic phonon mode frequencies. The results confirmed that the holmium phosphate glasses show an extraordinary elastic behaviour under high pressures

  20. Hydrogen peroxide (H2O2) irreversibly inactivates creatine kinase from Pelodiscus sinensis by targeting the active site cysteine.

    Science.gov (United States)

    Wang, Wei; Lee, Jinhyuk; Hao, Hao; Park, Yong-Doo; Qian, Guo-Ying

    2017-12-01

    Creatine kinase (EC 2.7.3.2, CK) plays an important role in cellular energy metabolism and homeostasis by catalysing the transfer of phosphate between ATP and creatine phosphate. In this study, we investigated the effects of H 2 O 2 on PSCKM (muscle type creatine kinase from Pelodiscus sinensis) by the integrating method between enzyme kinetics and docking simulations. We found that H 2 O 2 strongly inactivated PSCKM (IC 50 =0.25mM) in a first-order kinetic process, and targeted the active site cysteine directly. A conformational study showed that H 2 O 2 did not induce the tertiary structural changes in PSCKM with no extensive exposure of hydrophobic surfaces. Sequential docking simulations between PSCKM and H 2 O 2 indicated that H 2 O 2 interacts with the ADP binding region of the active site, consistent with experimental results that demonstrated H 2 O 2 -induced inactivation. Our study demonstrates the effect of H 2 O 2 on PSCKM enzymatic function and unfolding, and provides important insight into the changes undergone by this central metabolic enzyme in ectothermic animals in response to the environment. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Structural, magnetic, and electronic transport properties of pyrochlore iridate Pr2Ir2O7

    Science.gov (United States)

    Kumar, Harish; Chaurasia, Rachna; Kumari, Pratibha; Paramanik, A. K.

    2018-04-01

    We have studied the structural, magnetic, and electronic transport properties of pyrochlore iridate Pr2Ir2O7. Structural investigation has been done using x-ray powder diffraction and Rietveld analysis. Pr2Ir2O7 crystallize in cubic crystallographic phase with Fd-3m space group. Temperature dependent magnetization data does not show magnetic bifurcation down to 2 K. Electrical resistivity data of Pr2Ir2O7 exhibits metallic behavior throughout temperature range. Below 50 K, a small rise in resistivity data of Pr2Ir2O7 is observed down to 12 K.

  2. K2-141 b A 5-M-circle plus super-Earth transiting a K7V star every 6.7 h

    DEFF Research Database (Denmark)

    Barragan, O.; Gandolfi, D.; Dai, F.

    2018-01-01

    We report on the discovery of K2-141 b (EPIC 246393474 b), an ultra-short-period super-Earth on a 6.7 h orbit transiting an active K7V star based on data from K2 campaign 12. We confirmed the planet's existence and measured its mass with a series of follow-up observations: seeing-limited MuSCAT i...

  3. Actinides and rare earths complexation with adenosine phosphate nucleotides

    International Nuclear Information System (INIS)

    Mostapha, Sarah

    2013-01-01

    Organophosphorus compounds are important molecules in both nuclear industry and living systems fields. Indeed, several extractants of organophosphorus compounds (such as TBP, HDEHP) are used in the nuclear fuel cycle reprocessing and in the biological field. For instance, the nucleotides are organophosphates which play a very important role in various metabolic processes. Although the literature on the interactions of actinides with inorganic phosphate is abundant, published studies with organophosphate compounds are generally limited to macroscopic and / or physiological approaches. The objective of this thesis is to study the structure of several organophosphorus compounds with actinides to reach a better understanding and develop new specific buildings blocks. The family of the chosen molecules for this procedure consists of three adenine nucleotides mono, bi and triphosphate (AMP, adenosine monophosphate - ADP, adenosine diphosphate - ATP, adenosine triphosphate) and an amino-alkylphosphate (AEP O-phosphoryl-ethanolamine). Complexes synthesis was conducted in aqueous and weakly acidic medium (2.8-4) for several lanthanides (III) (Lu, Yb, Eu) and actinides (U (VI), Th (IV) and Am (III)). Several analytical and spectroscopic techniques have been used to describe the organization of the synthesized complexes: spectrometric analysis performed by FTIR and NMR were used to identify the functional groups involved in the complexation, analysis by ESI-MS and pH-metric titration were used to determine the solution speciation and EXAFS analyzes were performed on Mars beamline of the SOLEIL synchrotron, have described the local cation environment, for both solution and solid compounds. Some theoretical approaches of DFT were conducted to identify stable structures in purpose of completing the experimental studies. All solid complexes (AMP, ADP, ATP and AEP) have polynuclear structures, while soluble ATP complexes are mononuclear. For all synthesized complexes, it has been

  4. Structure-solubility relationships in fluoride-containing phosphate based bioactive glasses

    Science.gov (United States)

    Shaharyar, Yaqoot

    The dissolution of fluoride-containing bioactive glasses critically affects their biomedical applications. Most commercial fluoride-releasing bioactive glasses have been designed in the soda-lime-silica system. However, their relatively slow chemical dissolution and the adverse effect of fluoride on their bioactivity are stimulating the study of novel biodegradable materials with higher bioactivity, such as biodegradable phosphate-based bioactive glasses, which can be a viable alternative for applications where a fast release of active ions is sought. In order to design new biomaterials with controlled degradability and high bioactivity, it is essential to understand the connection between chemical composition, molecular structure, and solubility in physiological fluids.Accordingly, in this work we have combined the strengths of various experimental techniques with Molecular Dynamics (MD) simulations, to elucidate the impact of fluoride ions on the structure and chemical dissolution of bioactive phosphate glasses in the system: 10Na2O - (45-x) CaO - 45P2O5 - xCaF2, where x varies between 0 -- 10 mol.%. NMR and MD data reveal that the medium-range atomic-scale structure of thse glasses is dominated by Q2 phosphate units followed by Q1 units, and the MD simulations further show that fluoride tends to associate with network modifier cations to form alkali/alkaline-earth rich ionic aggregates. On a macroscopic scale, we find that incorporating fluoride in phosphate glasses does not affect the rate of apatite formation on the glass surface in simulated body fluid (SBF). However, fluoride has a marked favorable impact on the glass dissolution in deionized water. Similarly, fluoride incorporation in the glasses results in significant weight gain due to adsorption of water (in the form of OH ions). These macroscopic trends are discussed on the basis of the F effect on the atomistic structure of the glasses, such as the F-induced phosphate network re-polymerization, in a

  5. Electronic structure of layered ferroelectric high-k titanate La2Ti2O7

    Science.gov (United States)

    Atuchin, V. V.; Gavrilova, T. A.; Grivel, J.-C.; Kesler, V. G.

    2009-02-01

    The electronic structure of binary titanate La2Ti2O7 has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La2Ti2O7 are determined as αTi = 872.4 and αO = 1042.3 eV. Chemical bonding effects have been discussed with binding energy (BE) differences ΔTi = (BE O 1s - BE Ti 2p3/2) = 71.6 eV and ΔLa = (BE La 3d5/2 - BE O 1s) = 304.7 eV as key parameters in comparison with those in several titanium- and lanthanum-bearing oxides.

  6. Electronic structure of layered ferroelectric high-k titanate La2Ti2O7

    International Nuclear Information System (INIS)

    Atuchin, V V; Gavrilova, T A; Grivel, J-C; Kesler, V G

    2009-01-01

    The electronic structure of binary titanate La 2 Ti 2 O 7 has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La 2 Ti 2 O 7 are determined as α Ti = 872.4 and α O = 1042.3 eV. Chemical bonding effects have been discussed with binding energy (BE) differences Δ Ti = (BE O 1s - BE Ti 2p 3/2 ) = 71.6 eV and Δ La = (BE La 3d 5/2 - BE O 1s) = 304.7 eV as key parameters in comparison with those in several titanium- and lanthanum-bearing oxides.

  7. Chemical, structural and magnetic studies of new mono- and diphosphates appearing in ternary diagrams AO-CuO-(P2O5); A= Mg, Ca, Sr, Ba

    International Nuclear Information System (INIS)

    Moqine, A.

    1990-01-01

    A systematic study of mixed mono- and diphosphates of AO-CuO-(P 2 O 5 ) systems (A= Mg, Ca, Sr, Ba) has been carried out. This study showed up, on one hand, continuous and wide ranges in magnesium system and on the other hand, eight new phases in the other systems: Sr sub 18 Cu sub 3 (PO 4 ) 14 , A 2 Cu (PO 4 ) 2 , (A= Sr, Ba), Sr 3 Cu 3 (PO 4 ) 4 , BaCu 2 (PO 4 ) 2 and ACu(P 2 O 7 ) (A= Ca, Sr, Ba). The crystalline structures of SrCu(P 2 O 7 ), BaCu(P 2 O 7 ),Sr 3 Cu 3 (PO 4 ) 4 and BaCu 2 (PO 4 ) 2 phosphates have been described and discussed. The first compound presents a Tunnel structure and the three others have Foliation structures. The magnetic behaviours of some Cu sup 2+ ions phos-phates have been correlated to their crystalline structures. The experimental data have been parametered using the Ising model and/or the Heisenberg model. In this work, three Ising theoretical models have been developed. This magnetic study showed up new chains of antiferro- or ferrimagnetic Cu sup 2+ ions. 59 figs., 32 tabs., 113 refs. (author)

  8. Investigation into the magnetic properties of pyrochlore-type rare-earth hafnates

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Jung Hwan; Kremer, Reinhard K.; Lin, Chengtian [MPI for Solid State Research, Stuttgart (Germany)

    2015-07-01

    Cubic rare-earths transition metal pyrochlores with composition R{sub 2}TM{sub 2}O{sub 7} have attracted broad attention because of their unusual magnetic ground state properties related to geometrical frustration of the pyrochlores lattice. So far, the investigation focused mainly on 3d and 4d transition metal systems. The magnetic properties of rare-earths 5d TM pyrochlores are comparatively less well studied. Here we report on the single-crystal growth and the magnetic properties of some rare-earth hafnates (R =Nd, Gd, Dy; TM = Hf) of composition R{sub 2}Hf{sub 2}O{sub 7}. Nd{sub 2}Hf{sub 2}O{sub 7} and Gd{sub 2}Hf{sub 2}O{sub 7} crystallize with the cubic pyrochlores structure whereas diverging reports on the structure of Dy{sub 2}Hf{sub 2}O{sub 7} are available in literature. Crystals of R{sub 2}Hf{sub 2}O{sub 7} have been grown and their structural and magnetic properties have been investigated. Our investigations confirm Nd{sub 2}Hf{sub 2}O{sub 7} and Gd{sub 2}Hf{sub 2}O{sub 7} to crystallize in the cubic pyrochlores structure. Antiferromagnetic ordering below ∝0.5 K has been observed by magnetic susceptibility and heat capacity measurements for both compounds.

  9. In vitro bioactivity of soda lime borate glasses with substituted SrO in sodium phosphate solution

    Directory of Open Access Journals (Sweden)

    Mohamed A. Marzouk

    2014-09-01

    Full Text Available Borate glasses with the basic composition 0.6B2O3·0.2Na2O·0.2CaO and SrO progressively substituting CaO were prepared and characterized for their bone-bonding ability. The obtained glasses were thermally treated and converted to their glass-ceramic derivatives. In this study, FTIR spectral analyses were done for the prepared glasses and glass-ceramics before and after immersion in a sodium phosphate solution for extended times. The appearance of two IR bands within the spectral range 550–680 cm-1 after immersion confirms the formation of hydroxyapatite. X-ray diffraction studies and scanning electron microscope analysis supported the obtained infrared spectroscopy results. The solubility test (measurements of the weight loss in aqueous sodium phosphate solution was conducted for measuring the dissolution of both glassy and crystalline derivatives to find out the role of SrO. The corrosion behaviour of the glasses and glass-ceramics indicate the increase of weight loss with the increase of SrO content. Different suggested proposals were introduced to explain this abnormal behaviour.

  10. Na3Co2(AsO4(As2O7: a new sodium cobalt arsenate

    Directory of Open Access Journals (Sweden)

    Abderrahmen Guesmi

    2012-07-01

    Full Text Available In the title compound, trisodium dicobalt arsenate diarsenate, Na3Co2AsO4As2O7, the two Co atoms, one of the two As and three of the seven O atoms lie on special positions, with site symmetries 2 and m for the Co, m for the As, and 2 and twice m for the O atoms. The two Na atoms are disordered over two general and special positions [occupancies 0.72 (3:0.28 (3 and 0.940 (6:0.060 (6, respectively]. The main structural feature is the association of the CoO6 octahedra in the ab plane, forming Co4O20 units, which are corner- and edge-connected via AsO4 and As2O7 arsenate groups, giving rise to a complex polyhedral connectivity with small tunnels, such as those running along the b- and c-axis directions, in which the Na+ ions reside. The structural model is validated by both bond-valence-sum and charge-distribution methods, and the distortion of the coordination polyhedra is analyzed by means of the effective coordination number.

  11. Electronic structure of layered ferroelectric high-k titanate Pr2Ti2O7

    International Nuclear Information System (INIS)

    Atuchin, V.V.; Gavrilova, T.A.; Grivel, J.-C.; Kesler, V.G.; Troitskaia, I.B.

    2012-01-01

    The spectroscopic parameters and electronic structure of binary titanate Pr 2 Ti 2 O 7 have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Pr 2 Ti 2 O 7 have been determined as α Ti =872.8 and α O =1042.3 eV. Variations of cation–anion bond ionicity have been discussed using binding energy differences Δ Ti =(BE O 1s–BE Ti 2p 3/2 )=71.6 eV and Δ Pr =BE(Pr 3d 5/2 )−BE(O 1s)=403.8 eV as key parameters in comparison with those of other titanium- and praseodymium-bearing oxides. Highlights: ► Solid state synthesis of polar titanate Pr 2 Ti 2 O 7 . ► Structural and spectroscopic properties and electronic structure determination. ► Ti–O and Pr–O bonding analysis using Ti 2p 3/2 , Pr 3d 5/2 and O 1s core levels.

  12. Microstructure of yttric calcium phosphate bioceramic coatings synthesized by laser cladding

    International Nuclear Information System (INIS)

    Wang Diangang; Chen Chuanzhong; Ma Jie; Lei Tingquan

    2007-01-01

    The yttric calcium phosphate (CaP) coatings were in situ prepared on pure titanium substrate by laser cladding. The morphologies and phases constitution of CaP coatings were studied by electron probe microanalysis, X-ray diffraction and so on. The bonding state between the coating and the substrate is fine metallurgical combination, and the addition of yttria can fine the structure and increase the tensile strength of the coatings. The X-ray result shows that the coating is composed of the phases of HA, α-Ca 2 P 2 O 7 , β-Ca 2 P 2 O 7 and CaTiO 3

  13. Studies on the structural stability of Co2P2O7 under pressure

    Science.gov (United States)

    Wang, W. P.; Pang, H.; Jin, M. L.; Shen, X.; Yao, Y.; Wang, Y. G.; Li, Y. C.; Li, X. D.; Jin, C. Q.; Yu, R. C.

    2018-05-01

    The crystal structural evolution of Co2P2O7 was studied by using in situ high pressure angle dispersive x-ray diffraction with synchrotron radiation. The results demonstrate that the α phase of Co2P2O7 goes through a partially irreversible structural transformation to β phase under pressure. The pressure is conductive to reduce the longest Cosbnd O bond length of the α phase, and then more uniform Cosbnd O bonds and regular hexagonal arrangement of CoO6 octahedra of the β phase are favored. According to the Birch-Murnaghan equation, the fitted bulk modulus B0 is 158.1(±5.6) GPa for α phase and 276.5(±6.5) GPa for β phase. Furthermore, the first-principles calculations show that these two phases of Co2P2O7 have almost equal total energies, and also have similar band structures and spin-polarized density of states at their ground states. This may be the reason why these two phases of Co2P2O7 can coexist in the pressure released state. It is found that the band gap energies decrease with increasing pressure for both phases.

  14. Structure and Degradation Behaviour of Calcium Phosphate Glasses

    International Nuclear Information System (INIS)

    Silva, A M B; Correia, R N; Fernandes, M H V; Oliveira, J M M

    2011-01-01

    Some studies have shown a relationship between glass structure and in vitro mineralization, generally associated with the rate of glass degradation, nature of released ions and subsequent Ca-P precipitation on glass surfaces when immersed in a Simulated Body Fluid (SBF). The knowledge of the ionic species distribution in glasses and of the involved bond strengths can be used to assess the in vitro behaviour of a glass. The role of ions such as silicon or titanium is of major importance for the development of new compositions and also for the control of glass degradation behaviour. A comparative study with two calcium phosphate glasses series was performed: Both glasses series - one with Si and another with Ti - include P 2 O 5 and alkaline earth ions in their compositions. Surface reactivity of glasses from the SiO 2 -containing system have been studied in SBF showing the precipitation of a Ca-P surface layer that increases with increasing MgO/CaO ratio. In glasses from the TiO 2 -containing series it is shown that the increase of TiO 2 contributes for the stabilization of the glass network thus allowing the control of their degradation rate when immersed in SBF. The relationship between structural features of these calcium-phosphate glasses and their degradation behaviour in SBF is discussed in terms of the structural role of Si and Ti ions. It is concluded that glasses with less interconnected species favour the Ca-P surface precipitation. The understanding of this relationship in synthetic physiological fluids is expected to allow the tailoring of glass degradation rates in complex biological systems.

  15. Crystallization behavior of Li2O-SiO2, Na2O-SiO2 and Na2O-CaO-SiO2 glasses; Li2O-SiO2, Na2O-SiO2, Na2O-CaO-SiO2 kei glass no kessho sekishutsu kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Tsutsumi, K.; Otake, J.; Nagasaka, T.; Hino, M. [Tohoku University, Sendai (Japan)

    1998-06-01

    It has been known that crystallization of mold powder is effective on the disturbance of heat transfer between mold and solidified shell in production of middle carbon steel slabs in continuous casting process. But it has not yet been made clear which composition of mold powder is the most suitable for crystallization. The crystallization behavior of Li2O-SiO2, Na2O-SiO2 and Na2O-CaO-SiO2 glasses was observed by differential thermal analysis (DTA) and hot-thermocouple methods with DTA in the present work. As a result, addition of alkaline metal and alkaline earth metal oxides to SiO2 increased the critical cooling rate for glass formation in binary system of Li2O-SiO2 and Na2O-SiO2 and Li2O-SiO2 system crystallized easier than Na2O-SiO2 system. In ternary system of Na2O-CaO-SiO2, addition of Na2O hurried the critical cooling rate at CaO/SiO2=0.93 mass ratio, but the rate was almost constant in the composition range of more than 15 mass% Na2O. The slag of CaO/SiO2=0.93 made the rate faster than the slag of CaO/SiO2=0.47 at constant content of 10mass% Na2O. 17 refs., 10 figs., 3 tabs.

  16. Partitioning of the rare earths and actinides between R7T7 nuclear glass alteration products and solution according to disposal conditions; Partage des terres rares et des actinides entre solution et produits d`alteration du verre nucleaire type R7T7 en fonction des conditions de stockage

    Energy Technology Data Exchange (ETDEWEB)

    Menard, O

    1995-10-25

    The alteration of nuclear glass by water is liable to release radionuclides into the environment. Determining the release kinetics of these elements and their aqueous chemical forms are therefore essential steps in establishing the safety of a geological repository site. Leach tests were conducted with a nonradioactive specimen of the French ``R7T7`` light water containment glass spiked with U and Th, and with two R7T7 specimens spiked with {sup 237}Np and {sup 239}Pu, respectively. The alteration solution compositions were representative of deep groundwater and contained carbonate, sulfate, phosphate, fluorine and chlorine ions. The release of U, Th, Np and Pu, as well as of the rare earths La, Ce and Nd were monitored by ICP mass spectrometry and by {alpha} spectrometry. Scanning and transmission electron microscopic examination of the nonradioactive altered glass surfaces was also performed to assess the partitioning balance for the rare earths, U and Th between the glass alteration products and solution. The mobility of these elements depends on two competing mechanisms. The rare earths and thorium are incorporated in the alteration products (gel); the retention process is assumed to involve chemisorption or coprecipitation, enhanced in the gel layer by the presence of phosphate ions in particular. Conversely, the aqueous species in the alteration solutions (mainly anions) form complexes with the actinides and rare earths; this phenomenon is particularly evident with U and Np. The presence of carbonate ions favors this mobility. Plutonium differs from U and Np in that it is adsorbed mainly on colloids formed by glass dissolution, the principal factors governing its chemical evolution in solution. (author). refs., 122 figs., 185 tabs.

  17. Calcium phosphate glass-ceramics for bioactive coating on a {beta}-titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kasuga, T.; Nogami, M. [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Niinomi, M. [Department of Production Systems Engineering, Toyohashi University of Technology, Tenpaku-cho, Toyohashi 441-8580 (Japan)

    2003-07-01

    The formation of a porous coating is the decisive feature for the bio-compatibility of silica-free calcium phosphate glass ceramics on alloy surfaces like the {beta}-Ti structured Ti-29Nb-13Ta-4.6Zr used in this work. The ceramic composition is highly important: 50CaO-40P{sub 2}O{sub 5}-7Na{sub 2}O-3TiO{sub 2} glass powder produces a pore-free coating unable to bind hydroxyapatite, whereas 60CaO-30P{sub 2}O{sub 5}-7Na{sub 2}O-3TiO{sub 2} glass incorporates pores from which a crystalline hydroxyapatite phase can grow over the surface from simulated body fluid (see Figure). (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  18. Synthesis, characterization and luminescence study of Eu3+ doped Y2Sn2O7 nano-particles

    International Nuclear Information System (INIS)

    Nigam, Sandeep; Sudarsan, V.; Vatsa, R.K.

    2011-01-01

    In recent years, advanced materials derived from Pyrochlore-type oxides (A 2 B 2 O 7 ), have been of extensive scientific and technological interest. Chemical substitution of A or B sites of pyrochlore oxide by rare earth ions is a widely used approach to prepare thermally stable, lanthanide ion doped luminescent materials. The present study deals with the synthesis and characterization of Eu 3+ doped Y 2 Sn 2 O 7 : nanoparticles prepared by the hydrolysis of Y 3+ , Sn 4+ , and Eu 3+ in ethylene glycol medium followed by heating at 700 deg C for 4 hours. As prepared samples are amorphous in nature and 700 deg C heated sample showed well crystalline pyrochlore structure in XRD studies. Average particle size is calculated from the width of the X-ray diffraction peaks and found to t be around 5 nm. Luminescence measurements were carried out for as prepared and 700 deg C heated samples. The undoped as prepared sample showed a broad emission peak around 420 nm after excitation at 285 nm. While for 700 deg C undoped heated sample, the peak maxima was shifted to 435 nm. The emission spectrum for doped as prepared samples is characterized by both host emission around 420 nm along with the characteristic Eu 3+ emission peaks in the visible region. However, very poor Eu 3+ emission from heated sample was observed

  19. Construction of order mesoporous (Eu–La)/ZnO composite material and its luminescent characters

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Na; Liu, Yu; Li, Zi-Wei [School of Chemistry & Environmental Engineering, Changchun University of Science and Technology, Changchun 130022 (China); Yu, Hui, E-mail: yh2001101@163.com [School of Chemistry & Environmental Engineering, Changchun University of Science and Technology, Changchun 130022 (China); Bai, Hao-tian [School of Chemistry & Environmental Engineering, Changchun University of Science and Technology, Changchun 130022 (China); Xia, Long, E-mail: xialong_aron@163.com [School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264209 (China); Feng, Da-wei [Changchun University of Science and Technology Science Park, Changchun 130022 (China); Guangdong College of Business and Technology, Zhaoqing 526020 (China); Zhang, Hong-bo; Dong, Xiang-ting; Wang, Tian-yang; Han, Ji; Wu, Rong-yi; Zhang, Qi [School of Chemistry & Environmental Engineering, Changchun University of Science and Technology, Changchun 130022 (China)

    2016-09-15

    For the first time, the order mesoporous zinc oxide was synthesized by a soft template synthesis method. The Eu and La phosphate were introduced into the prepared mesoporous zinc oxide by the high temperature solid phase method, and got the mesoporous rare earth/zinc oxide composite materials. The luminescence characters of the materials were studied. The influences of La to Eu luminescent properties had been studied, and the optimum proportion of Eu and La was discussed. The influences of La and Eu to ZnO luminescence properties were also been studied. La phosphate had the large influence to Eu luminescent. ZnO had a strong emission peak at 469 nm, which overlapped with the {sup 7}F{sub 0}–{sup 5}D{sub 2} transition excitation peak of Eu at 465 nm. It indicated that the effective energy transfer happened between ZnO and Eu, which strongly enhanced the luminescence intensity of Eu. At the same time, the Eu and La phosphates could regulate the defect density of ZnO, which could regulate the luminescent intensity of ZnO, and realized the adjustment of luminescent color between green and red light.

  20. Frustrated pyrochlore oxides, Y2Mn2O7, Ho2Mn2O7, and Yb2Mn2O7: Bulk magnetism and magnetic microstructure

    DEFF Research Database (Denmark)

    Greedan, J.E.; Raju, N.P.; Maignan, A.

    1996-01-01

    The bulk magnetic properties, including de and ac susceptibilities and heat capacity, of the pyrochlore oxides Ho2Mn2O7 and Yb2Mn2O7 are reported and compared with those of the previously studied Y2Mn2O7. In the latter case the magnetic Mn4+ ions occupy the 16c sites in Fd3m which define...... for all three materials are reported for the Q range 10(-2) Angstrom(-1) to 2x10(-1) Angstrom(-1) and the temperature range 6-100 K. Data for the full Q range can be fitted for all three materials to a model consisting of a Lorentzian and a Lorentzian-squared term, i.e., I(Q)=A/(Q(2)+1/xi(1)(2))+B/(Q(2......)+1/xi(2)(2))(2), a cross section commonly found in spin-glass-like materials. A surprising result is that the correlation lengths xi(1) and xi(2) are unequal and in general xi(2)>xi(1). xi(1) remains finite reaching maximum values which range from 10 to 20 Angstrom depending on the compound, while xi(2...

  1. Thermal expansion of lanthanum silicate oxyapatite (La9.33+2x(SiO4)6O2+3x), lanthanum oxyorthosilicate (La2SiO5) and lanthanum sorosilicate (La2Si2O7)

    International Nuclear Information System (INIS)

    Fukuda, Koichiro; Asaka, Toru; Uchida, Tomohiro

    2012-01-01

    Four types of powder specimens of La 9.33 (SiO 4 ) 6 O 2 (space group P6 3 /m and Z=1), La 9.33+2x (SiO 4 ) 6 O 2+3x with 0.06≤x≤0.13 (P6 3 /m and Z=1), La 2 SiO 5 (P2 1 /c and Z=4) and La 2 Si 2 O 7 (P2 1 /c and Z=4) were examined by high-temperature X-ray powder diffractometry to determine the changes in unit-cell dimensions up to 1473 K. The anisotropy of thermal expansion was demonstrated for the former two crystals to clarify the thermal behaviors of the highly c-axis-oriented polycrystals. With La 9.33 (SiO 4 ) 6 O 2 , the linear expansion coefficient of the a-axis (α a ) was 4.8×10 −6 K −1 and that of the c-axis (α c ) was 1.8×10 −6 K −1 in the temperature range from 298 to 1473 K. The α a - and α c -values of La 9.33+2x (SiO 4 ) 6 O 2+3x (0.06≤x≤0.13) were, respectively, 5.9×10 −6 K −1 and 2.3×10 −6 K −1 . The coefficients of mean linear thermal expansion were 4.9×10 −6 K −1 for La 2 SiO 5 and 6.0×10 −6 K −1 for La 2 Si 2 O 7 , which describe the thermal expansion behaviors of the randomly grain-oriented polycrystalline materials. - Graphical abstarct: Temperature dependence of the coefficients of thermal expansion (CTE). The linear CTE along the a-axes for La 9.33 (SiO 4 ) 6 O 2 and La 9.33+2x (SiO 4 ) 6 O 2+3x with 0.06≤x≤0.13. The mean linear CTE for La 2 SiO 5 and La 2 Si 2 O 7 . Highlights: ► We examined the thermal expansion of La 9.33+2x (SiO 4 ) 6 O 2+3x (x=0 and 0.06≤x≤0.13), La 2 SiO 5 and La 2 Si 2 O 7 ► Unit-cell dimensions were determined up to 1473 K by high-temperature X-ray diffraction ► Anisotropic expansion was clarified for La 9.33+2x (SiO 4 ) 6 O 2+3x (x=0 and 0.06≤x≤0.13) ► Mean linear thermal expansion was determined for La 2 SiO 5 and La 2 Si 2 O 7.

  2. Novel selenium containing boro-phosphate glasses: preparation and structural study.

    Science.gov (United States)

    Ciceo-Lucacel, R; Radu, T; Ponta, O; Simon, V

    2014-06-01

    We synthesized a new boro-phosphate glass system with different %mol SeO2 content by conventional melt quenching technique. All samples were obtained in a glassy state with the vitreous structure confirmed by X-ray diffraction analysis. Scanning electron microscopy (SEM) revealed some non-homogeneous domains on the glasses surface, and their tendency to link each other once the selenium oxide content increases. Energy-dispersive X-ray analysis (EDAX) indicated similar elemental composition in different regions of each sample. X-ray photoelectron spectroscopy (XPS) was used to determine the nature of chemical bonding and the elemental composition at the sample surfaces, and Fourier transform infrared (FT-IR) spectroscopy was used to determine the structural groups in the obtained glass structure. Based on FT-IR results, the glass structure at short range order consists mainly of small phosphate units such as pyrophosphate (i.e. P2O7(4-) dimmers or terminating groups at the end of phosphate chains) and some metaphosphate (i.e. PO3(-) middle groups in the phosphate chains) units. The boron atoms are mainly placed in three-coordinated sites in BØ3 or BØ2O(-) units. A small contribution of BØ4(-) units was also detected from the FT-IR spectra of glasses. For SeO2 content higher than 5mol%, the modifier role of selenium ions is strongly reflected on the local structure dominated in this case by pyrophosphate units. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Removal of phosphate from solution by adsorption and precipitation of calcium phosphate onto monohydrocalcite.

    Science.gov (United States)

    Yagi, Shintaro; Fukushi, Keisuke

    2012-10-15

    The sorption behavior and mechanism of phosphate on monohydrocalcite (CaCO(3)·H(2)O: MHC) were examined using batch sorption experiments as a function of phosphate concentrations, ionic strengths, temperatures, and reaction times. The mode of PO(4) sorption is divisible into three processes depending on the phosphate loading. At low phosphate concentrations, phosphate is removed by coprecipitation of phosphate during the transformation of MHC to calcite. The sorption mode at the low-to-moderate phosphate concentrations is most likely an adsorption process because the sorption isotherm at the conditions can be fitted reasonably with the Langmuir equation. The rapid sorption kinetics at the conditions is also consistent with the adsorption reaction. The adsorption of phosphate on MHC depends strongly on ionic strength, but slightly on temperature. The maximum adsorption capacities of MHC obtained from the regression of the experimental data to the Langmuir equation are higher than those reported for stable calcium carbonate (calcite or aragonite) in any conditions. At high phosphate concentrations, the amount of sorption deviates from the Langmuir isotherm, which can fit the low-to-moderate phosphate concentrations. Speciation-saturation analyses of the reacted solutions at the conditions indicated that the solution compositions which deviate from the Langmuir equation are supersaturated with respect to a certain calcium phosphate. The obtained calcium phosphate is most likely amorphous calcium phosphate (Ca(3)(PO(4))(2)·xH(2)O). The formation of the calcium phosphate depends strongly on ionic strength, temperature, and reaction times. The solubility of MHC is higher than calcite and aragonite because of its metastability. Therefore, the higher solubility of MHC facilitates the formation of the calcium phosphates more than with calcite and aragonite. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Plateau on temperature dependence of magnetization of nanostructured rare earth titanates

    Science.gov (United States)

    Rinkevich, A. B.; Korolev, A. V.; Samoylovich, M. I.; Demokritov, S. O.; Perov, D. V.

    2018-05-01

    Magnetic properties of nanocomposite materials containing particles of rare earth titanates of R2Ti2O7 type, where R is a rare earth ion, including "spin ice" materials are investigated. The descending branches of hysteresis loop have been studied in detail in temperature range from 2 to 50 K. It has been shown that nanocomposites with Yb2Ti2O7, Dy2Ti2O7 and Er2Ti2O7 particles have one intersection point of the descending branches in some temperature range unlike many other nanocomposites. It is shown that magnetization has only weak temperature dependence near this point. It has been obtained that nanocomposites with Pr2Ti2O7 and Nd2Ti2O7 particles have no hysteresis loop. All above findings point out to unusual magnetic structures of the studied samples.

  5. Activity of RE/sub 2/O/sub 3/ in liquid La/sub 2/O/sub 3/-Al/sub 2/O/sub 3/-CaF/sub 2/ and Ce/sub 2/O/sub 3/-CaO-CaF/sub 2/ slags

    International Nuclear Information System (INIS)

    Changzhen, W.; Shuqing, Y.; Qieng, D.

    1985-01-01

    In the course of electro-slag refining, if the slag contains rare earth oxides, the amount of rare earth introduced to the steel depends on the composition of the slag and other conditions. The main aim of this investigation is to study the activity of RE/sub 2/O/sub 3/ in the electro-slags of various compositions. One is the La/sub 2/O/sub 3/-CaO-CaF/sub 2/ ternary slag system and the other is the Ce/sub 2/O/sub 3/-CaO-CaF/sub 2/ slag system. The iso-activity diagram for RE/sub 2/O/sub 3/ and the liquid boundary for slags system were estimated

  6. Structural study and physical properties of a new phosphate KCuFe(PO4)2

    International Nuclear Information System (INIS)

    Badri, Abdessalem; Hidouri, Mourad; Lopez, Maria Luisa; Pico, Carlos; Wattiaux, Alain; Ben Amara, Mongi

    2011-01-01

    Single crystals of a new phosphate KCuFe(PO 4 ) 2 have been prepared by the flux method and its structural and physical properties have been investigated. This compound crystallizes in the monoclinic system with the space group P2 1 /n and its parameters are: a=7.958(3) A, b=9.931(2) A, c=9.039(2) A, β=115.59(3) o and Z=4. Its structure consists of FeO 6 octahedra sharing corners with Cu 2 O 8 units of edge-sharing CuO 5 polyhedra to form undulating chains extending infinitely along the b-axis. These chains are connected by the phosphate tetrahedra giving rise to a 3D framework with six-sided tunnels parallel to the [101] direction, where the K + ions are located. The Moessbauer spectroscopy results confirm the exclusive presence of octahedral Fe 3+ ions. The magnetic measurements show the compound to be antiferromagnetic with C m =5.71 emu K/mol and θ=-156.5 K. The derived experimental effective moment μ ex =6.76μ B is somewhat higher than the theoretical one of μ th =6.16μ B , calculated taking only into account the spin contribution for Fe 3+ and Cu 2+ cations. Electrical measurements allow us to obtain the activation energy (1.22 eV) and the conductivity measurements suggest that the charge carriers through the structure are the potassium cations. -- Graphical abstract: A projection along the [101] direction of the structure showing the six-edged tunnels, occupied by the K + ions. Display Omitted Highlights: → The reported structure is of a new type. → The structural model is supported by a Moessbauer spectroscopy study. → The magnetic susceptibility results are reported. → The electrical properties are discussed.

  7. Biocompatibility studies of endothelial cells on a novel calcium phosphate/SiO{sub 2}-xerogel composite for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Thimm, Benjamin W; Unger, Ronald E; Kirkpatrick, C James [Institute of Pathology, Johannes Gutenberg-University Mainz, Langenbeckstr.1, 55101 Mainz (Germany); Neumann, Hans-Georg [DOT GmbH, Charles-Darwin-Ring 1a, 18059 Rostock (Germany)], E-mail: runger@uni-mainz.de

    2008-03-01

    The bone biomaterial BONITmatrix, a nanoporous, granular scaffold composed of hydroxylapatite, calcium phosphate and SiO{sub 2}, linked by a dense collagen mesh, was tested for its biocompatibility using endothelial cells (EC) in the form of macrovascular HUVEC, microvascular HDMEC and the endothelial cell line ISOHAS-1. Cells were examined for their adherence and growth on the biomaterial and this was followed by confocal laser scanning microscopy after vital staining or immunocytochemical reactions, as well as by scanning electron microscopy. Macro- and microvascular ECs predominantly spread on BONITmatrix-collagen mesh-covered surfaces and fibres and maintained their typical morphology. As ECs in vivo must build up a functional vasculature, the seeded cells were further tested for proinflammatory expression markers and cytokine expression after lipopolysaccharide stimulation. Protein-coating studies revealed that BONITmatrix-collagen scaffolds needed human blood serum coating to successfully support the growth of ECs. All cells expressed endothelium-specific surface marker proteins such as PECAM-1, VE-cadherin and vWF. The in vitro data support recent in vivo studies and indicate that this calcium phosphate/SiO{sub 2}-xerogel composite could be a useful scaffold material for tissue engineering.

  8. Vibrational modes and Structure of Niobium(V) Oxosulfato Complexes in the Molten Nb2O5-K2S2O7-K2SO4 System Studied by Raman Spectroscopy

    DEFF Research Database (Denmark)

    Paulsen, Andreas L.; Borup, Flemming; Berg, Rolf W.

    2010-01-01

    The structural and vibrational properties of NbV oxosulfato complexes formed in Nb2O5-K2S2O7 and Nb2O5-K2S2O7-K2SO4 molten mixtures with 0 ... for the binary Nb2O5-K2S2O7 molten system indicate that the dissolution of Nb2O5 proceeds with consumption of S2O7 leading to the formation of a NbV oxosulfato complex according to Nb2O5 + nS2O7 --> C2n-; a simple formalism exploiting the relative Raman band intensities is used for determining the stoichiometric...... coefficient, n, pointing to n = 3 and to the following reaction: Nb2O5 + 3S2O7 --> 2NbO(SO4)3, which is consistent with the Raman spectra of the molten mixtures. Nb2O5 could be dissolved much easier when K2SO4 was present in an equimolar (1:1) SO4/Nb ratio; the incremental presence of K2SO4 in Nb2O5-K2S2O7...

  9. Effect of rare-earth composition on microstructure and pinning properties of Zr-doped (Gd, Y)Ba{sub 2}Cu{sub 3}O{subx} superconducting tapes.

    Energy Technology Data Exchange (ETDEWEB)

    Selvamanickam, V.; Chen, Y.; Zhang, Y.; Guevara, A.; Shi, T.; Yao, Y.; Majkic, G.; Lei, C.; Galtsyan, E.; Miller, D. J. (Materials Science Division); (Univ. Houston); (SuperPower Inc.)

    2012-01-01

    The effect of changing Gd + Y content from 1.2 to 1.6 in the precursor of (Gd,Y)Ba{sub 2}Cu{sub 3}O{sub 7} superconducting thin film tapes made by metal organic chemical vapor deposition (MOCVD) at a constant Gd:Y ratio and a fixed Zr content of 7.5% has been studied. The influence of changing the Gd:Y ratio from Gd = 0 to Y= 0 in 0.2 mol steps at a constant Gd + Y content of 1.2 in the precursor has also been investigated at a fixed Zr content of 7.5%. The critical current of these films is found to vary significantly as a function of rare-earth content as well as a function of rare-earth type. Even for a fixed Zr content, it is found that the critical current in the orientation of magnetic field parallel to the a-b plane and that in the orientation of field perpendicular to the a-b plane can be systematically varied with changing Gd + Y content as well as with changing Gd:Y ratio. The nanoscale defect structures along the a-b plane and along the c-axis are found to be sensitive to these changes in rare-earth content and type.

  10. Barium contributions to the valence electronic structure of YBa2Cu3O7-δ, PrBa2Cu3O7-δ, and other barium-containing compounds

    International Nuclear Information System (INIS)

    Mueller, D.R.; Wallace, J.S.; Jia, J.J.; O'Brien, W.L.; Dong, Q.; Callcott, T.A.; Miyano, K.E.; Ederer, D.L.

    1995-01-01

    Monochromatic photon beams were used to excite barium N IV,V soft x-ray emission spectra from YBa 2 Cu 3 O 7-δ , PrBa 2 Cu 3 O 7-δ , BaF 2 , and BaTiO 3 . Near threshold excitation was used to demonstrate that small contributions to the barium N V and N IV emission spectra in the energy region above the 5p→4d core-core transitions do not arise as satellite emission from transitions in multiply excited atoms but rather occur as a result of transitions from the valence states. The emission spectrum of YBa 2 Cu 3 O 7-δ and PrBa 2 Cu 3 O 7-δ reveals a contribution to the electronic density of states at the barium site in the region near the Fermi level. The YBa 2 Cu 3 O 7-δ compound is a superconductor and PrBa 2 Cu 3 O 7-δ is an insulator. It has been proposed that the difference between them is due to mixing of praseodymium and barium among the sites occupied by yttrium and barium, with an accompanying change in electronic structure. However, our measurements indicate that the barium partial density of states for the two compounds are essentially identical

  11. The fluorite-pyrochlore transformation of Ho2-yNdyZr2O7

    International Nuclear Information System (INIS)

    Clements, Richard; Hester, James R.; Kennedy, Brendan J.; Ling, Chris D.; Stampfl, Anton P.J.

    2011-01-01

    Twelve members of the Ho 2-y Nd y Zr 2 O 7 series, prepared using conventional solid state methods, have been characterised by neutron powder diffraction. Ho 2 Zr 2 O 7 has a defect fluorite structure whereas Nd 2 Zr 2 O 7 is found to adopt the ordered pyrochlore structure with the composition induced fluorite-pyrochlore transformation occurring near y=1. Rietveld analysis on the neutron data for all the compositions reveals an increase in lattice parameter as a function of y across the entire series, with a small discontinuity associated with the transformation. The neutron profile results suggest that domains of pyrochlore-type initially begin to form before crystallising into a separate phase, and therefore that anion and cation ordering processes are distinct. There is a strong correlation between the extent of disorder in the anion sublattice and the x-parameter of 48f oxygen. These results point the way to a better understanding of the stability observed in pyrochlore structures. - Graphical abstract: Neutron diffraction profiles for Nd 2-y Ho y Zr 2 O 7 type oxides reveal details of the transformation from the ordered pyrochlore structure (y=0) to the disordered fluorite structure (y=2). Highlights: → Structures of twelve members of the Ho 2-y Nd y Zr 2 O 7 series studied using neutron powder diffraction. → Domains of pyrochlore-type materials form at low doping levels. → Higher doping stabilises the pyrochlore. → Anion and cation ordering processes are distinct.

  12. Ph effect on tricalcium phosphate (Ca3(PO4)2) thermoluminescence

    International Nuclear Information System (INIS)

    Barrera V, A.; Zarate M, J.; Lemus R, J.; Sanchez, A.; Rivera M, T.

    2015-10-01

    The study of the ph effect is presented on thermoluminescent response of calcium phosphates synthesized by precipitation process. For the synthesis by precipitation, were used: calcium nitrate (Ca(NO 3 ) 2 and ammonium phosphate dibasic ((NH 4 ) 2 HPO 4 ) as precursors. Samples were obtained at ph 7, 8, 9 and 10 and subjected to a calcination s temperature of 1100 C. Samples were also irradiated with X rays of 6 MV to a dose of 2 Gy. Samples prior to irradiation showed no luminescence, the irradiated samples displayed a luminescent curve which is due to the X-ray response. Powders synthesized at ph 7 showed a well-defined peak centered at 267 grades C. The rest of the prepared samples showed a luminescent curve composed of several peaks. By analyzing the curve at ph 7 by the method of the shape of the curve, was found to have an order of 1.7, with an activation energy, E = 1.44 ± 0.04 eV. (Author)

  13. Uranium and thorium phosphate based matrices; syntheses, characterizations and lixiviation

    International Nuclear Information System (INIS)

    Dacheux, N.

    1995-03-01

    In the framework of the search for a ceramic material usable in the radioactive waste storage, uranium and thorium phosphates have been investigated. Their experimental synthesis conditions have been entirely reviewed, they lead to the preparation of four new compounds: U(UO 2 )(PO 4 ) 2 , U 2 O(PO 4 ) 2 , UC1PO 4 ,H 2 O, and Th 4 (PO 4 ) 4 , U 2 O 3 P 2 O 7 and Th 3 (PO 4 ) 4 . Characterization by several techniques (X-rays and neutron powder diffractions, UV-Visible and Infra-red spectroscopies, XPS,...) were performed. The ab initio structure determination of U(UO 2 )(PO 4 ) 2 has been achieved by X-rays and refined by neutron diffractions. Through its physico-chemical analysis, we found that this compound was a new mixed valence uranium phosphate in which U 4+ and UO 2 2+ ions are ordered in pairs along parallel chains according to a new type of arrangement. Reaction mechanism, starting from UC1PO 4 , 4H 2 O and based on redox processes of uranium in solid state was set up. From two main matrices U(UO 2 )(PO 4 ) 2 and Th 4 (PO 4 ) 4 P 2 O 7 , solid solutions were studied. They consist of replacement of U(IV) by Th(IV) and reversely. The leaching tests on pure, loaded and doped matrices were performed in terms of storage time, pH of solutions, and determined by the use of solids labelled with 230 U or by the measurement of uranyl concentration by Laser-Induced Time-Resolved Spectrofluorometry. Average concentration of uranium in the liquid phase is around 10 -4 M to 10 -6 M. Taking into account the very low solubilities of the studied phosphate ceramics, we estimated their chemical performances promising as an answer to the important nuclear waste problem, if we compare them to the glasses used at the present time. (author). 47 figs., 23 tabs., 6 appendixes

  14. Crystal-field study of magnetization and specific heat properties of frustrated pyrochlore Pr2Zr2O7

    International Nuclear Information System (INIS)

    Alam, J.; Jana, Y.M.; Biswas, A. Ali

    2016-01-01

    The experimental results of temperature dependent dc magnetic susceptibility, field dependent isothermal magnetization, magnetic specific heat and entropy of the pyrochlore Pr 2 Zr 2 O 7 are simulated and analyzed using appropriate D 3d crystal-field (CF) and anisotropic molecular field tensors at Pr-sites in the self-consistent mean-field approach involving four magnetically non-equivalent rare-earth spins on the tetrahedral unit of the pyrochlore structure. CF level pattern and wave-functions of the ground 3 H 4 multiplet of the Pr 3+ ions are obtained considering intermediate coupling between different Russell-Saunders terms of the 4f 2 electronic configurations of Pr-ion and J-mixing effects. CF analysis shows that the CF ground-state of the Pr 3+ ion in Pr 2 Zr 2 O 7 is a well-isolated doublet, with significant admixtures of terms coming from |M J =±4〉 and |M J =±1〉, and the Pr-spins are effectively Ising-like along the local <111> axes. Magnetic specific heat in zero-field is simulated by considering a temperature dependence of the exchange splitting of the ground doublet. - Highlights: • Full CF diagonalization using intermediate coupling and J-mixing. • Pr-spins are Ising-like along local [111] axis. • Magnetic specific heat is due to temperature dependence exchange splitting of ground CF doublet.

  15. On the Fermi surface of YBa2Cu3O7

    International Nuclear Information System (INIS)

    Peter, M.; Manuel, A.A.; Hoffmann, L.; Sadowski, W.

    1992-01-01

    We show that the signature of a Fermi surface sheet of YBa 2 Cu 3 O 7-δ may be obtained unambiguously from twinned crystals. Comparison of electron-positron momentum density from YBa 2 Cu 3 O 7-δ measured both in insulating and (superconducting) twinned phases leads to a decisive further proof of the existence of the Fermi surface in the metallic YBa 2 Cu 3 O 7-δ . In addition, measurements on untwinned YBA 2 Cu 3 O 7-δ single crystals reveal also a ridge Fermi surface sheet attributed by band structure calculations to CuO chains. 14 refs., 3 figs

  16. Luminescence – structure relationships in MYP{sub 2}O{sub 7}:Eu{sup 3+} (M=K, Rb, Cs)

    Energy Technology Data Exchange (ETDEWEB)

    Watras, A., E-mail: A.Watras@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, PAS, Okolna 2, 50-422 Wroclaw (Poland); Boutinaud, P. [Université Clermont Auvergne, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); Pązik, R.; Dereń, P.J. [Institute of Low Temperature and Structure Research, PAS, Okolna 2, 50-422 Wroclaw (Poland)

    2016-07-15

    In this work we present the series of MYP{sub 2}O{sub 7} phosphates doped with 3% of Eu{sup 3+} ions. All samples were prepared using wet-chemistry methods. The structural properties were characterized by XRD and Raman spectroscopy. The detailed spectroscopic properties like emission spectra at 10 and 300 K, VUV excitation spectra, luminescence kinetics and luminescence temperature quenching were performed to determine the influence of alkali metal ion. In MYP{sub 2}O{sub 7} compounds, the Eu{sup 3+} ions enter two different sites – one with C{sub 1} symmetry (Y{sup 3+} sites) and one with S{sub 4} site (M{sup +} site). All phosphors have a broad charge transfer (CT) absorption band located in the UV region (200–250 nm). The ratio between CT and 4f–4f bands is decreasing with increasing the alkali metal ion size. The mechanisms responsible of luminescence temperature quenching are thermalization of higher lying {sup 5}D{sub J} levels, energy transfer between two nearby Eu{sup 3+} sites and non-radiative losses on defects in the host lattices.

  17. New silicate-germanate Cs2Pb2[(Si0.6Ge0.4)2O7] from the series A2Pb2[B2O7], A = K, Cs, B = Si, Ge with the umbrella-like [PbO3]4- group

    Science.gov (United States)

    Belokoneva, Elena L.; Morozov, Ivan A.; Volkov, Anatoly S.; Dimitrova, Olga V.; Stefanovich, Sergey Yu.

    2018-04-01

    New silicate-germanate Cs2Pb2[(Si0.6Ge0.4)2O7] was synthesized in multi-components hydrothermal solution with 20 w.% concentration of Cs2CO3 mineralizer, pH = 10. Novel mixed compound belongs to the structure type A2Pb2[B2O7] previously indicated for powders with A = K, B=Si or Ge. Singe crystal structure determination of Cs2Pb2[(Si0.6Ge0.4)2O7] revealed the need for the correction of the space group of the earlier suggested structural model from P-3 to P-3m1, as well as for the splitting of the Pb-atom position. Umbrella-like groups [PbO3]4- are located between [(Si,Ge)O4]4- tetrahedra in mica-like honeycomb layers and play the role of tetrahedra with the Pb-lone-pair as the forth apex. Crystal chemical comparison revealed similarities and differences with the classical structure type of α-celsian Ba[Al2Si2O8] with the tetrahedral double layer. Recently investigated nonlinear optical acentric borates Pb2(BO3)(NO3) and Pb2(BO3)Cl are both related to this structural type, possessing umbrella-like groups [PbO3]4- and honeycomb layers [Pb2(BO3)]+ with the BO3-triangles on the tetrahedral positions.

  18. Phase Competition in the Palmer-Chalker X Y Pyrochlore Er2Pt2O7

    Science.gov (United States)

    Hallas, A. M.; Gaudet, J.; Butch, N. P.; Xu, Guangyong; Tachibana, M.; Wiebe, C. R.; Luke, G. M.; Gaulin, B. D.

    2017-11-01

    We report neutron scattering measurements on Er2Pt2O7 , a new addition to the X Y family of frustrated pyrochlore magnets. Symmetry analysis of our elastic scattering data shows that Er2Pt2O7 orders into the k =0 , Γ7 magnetic structure (the Palmer-Chalker state), at TN=0.38 K . This contrasts with its sister X Y pyrochlore antiferromagnets Er2Ti2O7 and Er2Ge2O7 , both of which order into Γ5 magnetic structures at much higher temperatures, TN=1.2 and 1.4 K, respectively. In this temperature range, the magnetic heat capacity of Er2Pt2O7 contains a broad anomaly centered at T*=1.5 K . Our inelastic neutron scattering measurements reveal that this broad heat capacity anomaly sets the temperature scale for strong short-range spin fluctuations. Below TN=0.38 K , Er2Pt2O7 displays a gapped spin-wave spectrum with an intense, flat band of excitations at lower energy and a weak, diffusive band of excitations at higher energy. The flat band is well described by classical spin-wave calculations, but these calculations also predict sharp dispersive branches at higher energy, a striking discrepancy with the experimental data. This, in concert with the strong suppression of TN, is attributable to enhanced quantum fluctuations due to phase competition between the Γ7 and Γ5 states that border each other within a classically predicted phase diagram.

  19. The pH behavior of a 2-aminoethyl dihydrogen phosphate zwitterion studied with NMR-titrations

    Science.gov (United States)

    Myller, A. T.; Karhe, J. J.; Haukka, M.; Pakkanen, T. T.

    2013-02-01

    In this study a bifunctional 2-aminoethyl dihydrogen phosphate (AEPH2) was 1H and 31P NMR characterized in a pH range of 1-12 in order to determine the zwitterion properties in different pH regions in H2O and D2O solutions. NMR was also used to determine the pH range where AEPH2 exists as a zwitterion. The phosphate group has two deprotonation points, around pH 1 and 6, while the amino group deprotonates at pH 11. The zwitterion form of AEPH2 (NH3+sbnd CHsbnd CHsbnd OPOH) exists as the main ion between pH 1 and 6 in water solutions and also in the solid state.

  20. Implications of the (H2O)n + CO ↔ trans-HCOOH + (H2O)n-1 (n = 1, 2, and 3) reactions for primordial atmospheres of Venus and Earth

    Science.gov (United States)

    Vichietti, R. M.; Spada, R. F. K.; da Silva, A. B. F.; Machado, F. B. C.; Haiduke, R. L. A.

    2018-04-01

    The forward and backward (H2O)n + CO ↔ HCOOH + (H2O)n-1 (n = 1, 2, and 3) reactions were studied in order to furnish trustworthy thermochemical and kinetic data. Stationary point structures involved in these chemical processes were achieved at the B2PLYP/cc-pVTZ level so that the corresponding vibrational frequencies, zero-point energies, and thermal corrections were scaled to consider anharmonicity effects. A complete basis set extrapolation was also employed with the CCSD(T) method in order to improve electronic energy descriptions and providing therefore more accurate results for enthalpies, Gibbs energies, and rate constants. Forward and backward rate constants were encountered at the high-pressure limit between 200 and 4000 K. In turn, modified Arrhenius' equations were fitted from these rate constants (between 700 and 4000 K). Next, considering physical and chemical conditions that have supposedly prevailed on primitive atmospheres of Venus and Earth, our main results indicate that 85-88 per cent of all water forms on these atmospheres were monomers, whereas (H2O)2 and (H2O)3 complexes would represent 12-15 and ˜0 per cent, respectively. Besides, we estimate that Earth's and Venus' primitive atmospheres could have been composed by ˜0.001-0.003 per cent of HCOOH when their temperatures were around 1000-2000 K. Finally, the water loss process on Venus may have occurred by a mechanism that includes the formic acid as intermediate species.

  1. Metal Phosphate-Supported Pt Catalysts for CO Oxidation

    Directory of Open Access Journals (Sweden)

    Xiaoshuang Qian

    2014-12-01

    Full Text Available Oxides (such as SiO2, TiO2, ZrO2, Al2O3, Fe2O3, CeO2 have often been used to prepare supported Pt catalysts for CO oxidation and other reactions, whereas metal phosphate-supported Pt catalysts for CO oxidation were rarely reported. Metal phosphates are a family of metal salts with high thermal stability and acid-base properties. Hydroxyapatite (Ca10(PO46(OH2, denoted as Ca-P-O here also has rich hydroxyls. Here we report a series of metal phosphate-supported Pt (Pt/M-P-O, M = Mg, Al, Ca, Fe, Co, Zn, La catalysts for CO oxidation. Pt/Ca-P-O shows the highest activity. Relevant characterization was conducted using N2 adsorption-desorption, inductively coupled plasma (ICP atomic emission spectroscopy, X-ray diffraction (XRD, transmission electron microscopy (TEM, CO2 temperature-programmed desorption (CO2-TPD, X-ray photoelectron spectroscopy (XPS, and H2 temperature-programmed reduction (H2-TPR. This work furnishes a new catalyst system for CO oxidation and other possible reactions.

  2. Crystal structures and thermal decomposition of permanganates AE[MnO{sub 4}]{sub 2} . n H{sub 2}O with the heavy alkaline earth elements (AE=Ca, Sr and Ba)

    Energy Technology Data Exchange (ETDEWEB)

    Henning, Harald; Bauchert, Joerg M.; Conrad, Maurice; Schleid, Thomas [Stuttgart Univ. (Germany). Inst. fuer Anorganische Chemie

    2017-10-01

    Reexamination of the syntheses and crystal structures as well as studies of the thermal decomposition of the heavy alkaline earth metal permanganates Ca[MnO{sub 4}]{sub 2} . 4 H{sub 2}O, Sr[MnO{sub 4}]{sub 2} . 3 H{sub 2}O and Ba[MnO{sub 4}]{sub 2} are the focus of this work. As an alternative to the very inelegant Muthmann method, established for the synthesis of Ba[MnO{sub 4}]{sub 2} a long time ago, we employed a cation-exchange column loaded with Ba{sup 2+} cations and passed through an aqueous potassium-permanganate solution. We later used this alternative also with strontium- and calcium-loaded columns and all the compounds synthesized this way were indistinguishable from the products of the established methods. Ca[MnO{sub 4}]{sub 2} . 4 H{sub 2}O exhibiting [CaO{sub 8}] polyhedra crystallizes in the orthorhombic space group Pccn with the lattice parameters a=1397.15(9), b=554.06(4) and c=1338.97(9) pm with Z=4, whereas Sr[MnO{sub 4}]{sub 2} . 3 H{sub 2}O with [SrO{sub 10}] polyhedra adopts the cubic space group P2{sub 1}3 with a=964.19(7) pm and Z=4. So the harder the AE{sup 2+} cation, the higher its demand for hydration in aqueous solution. Consequently, the crystal structure of Ba[MnO{sub 4}]{sub 2} in the orthorhombic space group Fddd with a=742.36(5), b=1191.23(7) and c=1477.14(9) pm with Z=8 lacks any crystal water, but contains [BaO{sub 12}] polyhedra. During the thermal decomposition of Ca[MnO{sub 4}]{sub 2} . 4 H{sub 2}O, the compound expels up to two water molecules of hydration, before the crystal structure collapses after the loss of the third H{sub 2}O molecule at 157 C. The crystal structure of Sr[MnO{sub 4}]{sub 2} . 3 H{sub 2}O breaks down after the expulsion of the third water molecule as well, but this already occurs at 148 C. For both the calcium and the strontium permanganate samples, orthobixbyite-type α-Mn{sub 2}O{sub 3} and the oxomanganates(III,IV) AEMn{sub 3}O{sub 6} (AE=Ca and Sr) remain as final decomposition products at 800 C

  3. Bioleaching of rare earth elements from monazite sand.

    Science.gov (United States)

    Brisson, Vanessa L; Zhuang, Wei-Qin; Alvarez-Cohen, Lisa

    2016-02-01

    Three fungal strains were found to be capable of bioleaching rare earth elements from monazite, a rare earth phosphate mineral, utilizing the monazite as a phosphate source and releasing rare earth cations into solution. These organisms include one known phosphate solubilizing fungus, Aspergillus niger ATCC 1015, as well as two newly isolated fungi: an Aspergillus terreus strain ML3-1 and a Paecilomyces spp. strain WE3-F. Although monazite also contains the radioactive element Thorium, bioleaching by these fungi preferentially solubilized rare earth elements over Thorium, leaving the Thorium in the solid residual. Adjustments in growth media composition improved bioleaching performance measured as rare earth release. Cell-free spent medium generated during growth of A. terreus strain ML3-1 and Paecilomyces spp. strain WE3-F in the presence of monazite leached rare earths to concentrations 1.7-3.8 times those of HCl solutions of comparable pH, indicating that compounds exogenously released by these organisms contribute substantially to leaching. Organic acids released by the organisms included acetic, citric, gluconic, itaconic, oxalic, and succinic acids. Abiotic leaching with laboratory prepared solutions of these acids was not as effective as bioleaching or leaching with cell-free spent medium at releasing rare earths from monazite, indicating that compounds other than the identified organic acids contribute to leaching performance. © 2015 Wiley Periodicals, Inc.

  4. Microstructure of yttric calcium phosphate bioceramic coatings synthesized by laser cladding

    Energy Technology Data Exchange (ETDEWEB)

    Wang Diangang [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); Chen Chuanzhong [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China)]. E-mail: czchen@sdu.edu.cn; Ma Jie [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); Lei Tingquan [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2007-02-15

    The yttric calcium phosphate (CaP) coatings were in situ prepared on pure titanium substrate by laser cladding. The morphologies and phases constitution of CaP coatings were studied by electron probe microanalysis, X-ray diffraction and so on. The bonding state between the coating and the substrate is fine metallurgical combination, and the addition of yttria can fine the structure and increase the tensile strength of the coatings. The X-ray result shows that the coating is composed of the phases of HA, {alpha}-Ca{sub 2}P{sub 2}O{sub 7}, {beta}-Ca{sub 2}P{sub 2}O{sub 7} and CaTiO{sub 3}.

  5. Uncovering a new quasi-2D CuO2 plane between the YBa2Cu3O7 and CeO2 buffer layer of coated conductors

    Science.gov (United States)

    Li, Zhi-Xin; Cao, Jin-Jin; Gou, Xiao-Fan; Wang, Tian-Ge; Xue, Feng

    2018-01-01

    We report a discovery of the quasi-two-dimensional (quasi-2D) CuO2 plane between the superconductor YBa2Cu3O7 (YBCO) and CeO2 buffer layer (mostly used in the fabrication) of coated conductors through the atomistic computer simulations with the molecular dynamics (MD) and first-principle calculations. For an YBCO coated conductor with multilayer structures, the buffer layers deposited onto a substrate are mainly considered to transfer a strong biaxial texture from the substrate to the YBCO layer. To deeply understand the tuning mechanism of the texture transfer, exploring the complete atomic-level picture of the structure between the YBa2Cu3O7/CeO2 interfaces is firstly required. However, the related observation data have not been available due to some big challenges of experimental techniques. With the MD simulations, having tested the accuracy of the potential functions for the YBa2Cu3O7/CeO2 interface, we constructed a total of 54 possible atom stacking models of the interface and identified its most appropriate and stable structure according to the criterion of the interface adhesion energy and the coherent characterization. To further verify the stability of the identified structure, we performed the first-principle calculations to obtain the adhesion energy and developed the general knowledge of the interface structure. Finally, a coherent interface formed with a new built quasi-2D CuO2 plane that is structurally similar to the CuO2 plane inside bulk YBCO was determined.

  6. Temperature-Dependent Fermentation of d-Sorbitol in Escherichia coli O157:H7

    OpenAIRE

    Bouvet, O. M. M.; Pernoud, S.; Grimont, P. A. D.

    1999-01-01

    The influence of growth temperature on the ability to ferment d-sorbitol was investigated in Escherichia coli O157:H7. It was found that O157:H7 strains have a temperature-sensitive sorbitol phenotype. d-Sorbitol transport and sorbitol-6-phosphate dehydrogenase activities were expressed in sorbitol-fermenting cells grown at 30°C but only at a low level at 40°C. Sorbitol-positive variants able to transport d-sorbitol were easily selected at 30°C from culture of Sor− E. coli O157:H7 strains.

  7. Luminescence in Eu2+ and Ce3+ doped SrCaP2O7 phosphors

    Directory of Open Access Journals (Sweden)

    K.N. Shinde

    Full Text Available Eu2+ and Ce3+ doped SrCaP2O7 has been achieved by modified solid state diffusion in reducing atmosphere. The prepared phosphor powders have been identified by their characteristic X-ray diffraction patterns. The mixed phases of α-Sr2P2O7 type with orthorhombic and α-Ca2P2O7 type with monoclinic form were investigated. Its excitation wavelength ranging from 250 to 430 nm fits well with the characteristic emission of UV light-emitting diode (LED. The excitation and emission spectra indicate that these phosphors can be effectively excited by the near-UV light, and emits blue (visible range due to 4f7 → 4f65d1 transition of Eu2+ particularly, SrCaP2O7: Eu2+ whereas, photoluminescence excitation spectrum measurements of Ce3+ activated SrCaP2O7 shows that the phosphor can be efficiently excited by UV–Vis light from 280 to 310 nm to realize emission in the near visible range due to the 5d–4f transition of Ce3+ ions which is applicable for scintillation purpose. The impacts of doping of divalent europium and trivalent cerium on photoluminescence properties on SrCaP2O7 pyrophosphate phosphors were investigated and I propose a feasible interpretation. Keywords: Phosphor, Luminescence, XRD, LED, FTIR

  8. Use of linear free energy relationship to predict Gibbs free energies of formation of zirconolite phases (MZrTi2O7 and MHfTi2O7)

    International Nuclear Information System (INIS)

    Xu, H.

    1999-01-01

    In this letter, the Sverjensky-Molling equation derived from a linear free energy relationship is used to calculate the Gibbs free energies of formation of zirconolite crystalline phases (MZrTi 2 O 7 and MHfTi 2 O 7 ) from the known thermodynamic properties of the corresponding aqueous divalent cations (M 2+ ). Sverjensky-Molling equation is expressed as ΔG 0 f,M v X =a M v X ΔG 0 n,M 2+ +b M v X +β M v X r M 2+ , where the coefficients a M v X , b M v X , and β M v X characterize a particular structural family of M v X, r M 2+ is the ionic radius of M 2+ cation, ΔG f,M v X 0 is the standard Gibbs free energy of formation of M v X, and ΔG 0 n,M 2+ is the standard non-solvation energy of cation M 2+ . This relationship can be used to predict the Gibbs free energies of formation of various fictive phases (such as BaZrTi 2 O 7 , SrZrTi 2 O 7 , PbZrTi 2 O 7 , etc.) that may form solid solution with CaZrTi 2 O 7 in actual Synroc-based nuclear waste forms. Based on obtained linear free energy relationships, it is predicted that large cations (e.g., Ba and Ra) prefer to be in perovskite structure, and small cations (e.g., Ca, Zn, and Cd) prefer to be in zirconolite structure. (orig.)

  9. Development of AL_2O_3 - ZrO_2 ceramic composite reinforced with rare earth oxides (Y_2O)3) for inert coating of storage and transport systems of crude petroleum

    International Nuclear Information System (INIS)

    Silva, J.C.; Yadava, Y.P.; Sanguinetti Ferreira, R.A.; Albuquerque, L.T.

    2014-01-01

    The advancement of the oil sector has generated the need for the use of materials resistant to aggressive environments to oil. Although ceramics have high melting point and high hardness is, on the other hand, more fragile and less tough, which can cause damage to the metal structure. The Al_2O_3 based ceramics reinforced with rare earth oxide can improve tenaciousness and makes the ceramic material more resistant. This article aims to present the production of composite Al_2O_3 - Y_2O_3 stabilized ZrO_2 by uniaxial pressing, following sintering (1200-1350 deg C). Structural and microstructural characterizations as XRD (X-Ray Diffraction) and SEM (Scanning Electron Microscopy) and mechanical tests as Vickers hardness, % absorption and % linear shrinkage were conducted to evaluate the feasibility of using the composite and ceramic coating for storage and transportation of oil tanks. The results indicate that the proportions of 5%, 10% and 30% ZrO_2 make it suitable as a good composite suitable coating. (author)

  10. Uranium and thorium based phosphate matrix: synthesis, characterizations and lixiviation; Matrices a base de phosphate d'uranium et de thorium: syntheses, caracterisations et lixiviation

    Energy Technology Data Exchange (ETDEWEB)

    Dacheux, N

    1995-03-01

    In the framework of the search for a ceramic material usable in the radioactive waste storage, uranium and thorium phosphates have been investigated. Their experimental synthesis conditions have been entirely reviewed, they lead to the preparation of four new compounds: U(UO{sub 2})(PO{sub 4}){sub 2}, U{sub 2}O(PO{sub 4}){sub 2}, UCIPO{sub 4}, 4H{sub 2}O, and Th{sub 4}(PO{sub 4}){sub 4}P{sub 2}O{sub 7}. Experimental evidenced are advanced for non existent compounds such as: U{sub 3}(PO{sub 4}){sub 4}, U{sub 2}O{sub 3}P{sub 2}O{sub 7} and Th{sub 3} (PO{sub 4}){sub 4}. Characterization by several techniques (X-rays and neutron powder diffractions, UV-Visible and Infra-red spectroscopies, XPS,...) were performed. The ab initio structure determination of U(UO{sub 2})(PO{sub 4}){sub 2} has been achieved by X-rays and refined by neutron diffractions. Through its physico-chemical analysis, we found that this compound was a new mixed valence uranium phosphate in which U{sup 4+} and UO{sub 2}{sup 2+} ions are ordered in pairs along parallel chains according to a new type of arrangement. Reaction mechanism, starting from UCIPO{sub 4}, 4H{sub 2}O and based on redox processes of uranium in solid state was set up. From two main matrices U(UO{sub 2})(PO{sub 4}){sub 2} and Th{sub 4}(PO{sub 4}){sub 4}P{sub 2}O{sub 7}, solid solutions were studied. They consist of replacement of U(IV) by Th(IV) and reversely. The leaching tests on pure, loaded and doped matrices were performed in terms of storage time, pH of solutions, and determined by the use of solids labelled with {sup 230}U or by the measurement of uranyl concentration by Laser-Induced Time-Resolved Spectro-fluorimetry. Average concentration of uranium in the liquid phase is around 10{sup -4} M to 10{sup -6} M. Taking into account the very low solubilities of the studied phosphate ceramics, we estimated their chemical performances promising as an answer to the important nuclear waste problem, if we compare them to the glasses

  11. Reaction Mechanisms of Magnesium Potassium Phosphate Cement and its Application

    Science.gov (United States)

    Qiao, Fei

    magnesia. With the increase of magnesium ions in the solution, MgHPO4·7H2O is the first product precipitated, and its crystallization is accompanied with the increase of both pH and temperature. Beyond pH of 7, MgHPO4·7H 2O is transformed to Mg2KH(PO4)2·15H 2O, leading to a slight decrease of pH. The following dramatic increase of pH may be due to the formation of Mg2KH(PO4) 2·15H2O. Finally, Mg2KH(PO4) 2·15H2O gradually transforms to MgKPO4·6H 2O and leads to the second decrease of pH. Both increasing molar ratio of magnesium to phosphate (M/P) and decreasing the weight ratio of liquid to solid can speed up the reaction rate while addition of small amount of boron compounds can prolong the process even though the products are not changed. The retarding mechanism of boron compounds is related to their buffering effect on the pH of the solution, i.e. decreasing pH development rate, leads to delaying the formation of reaction products. The performance of MKPC based cementitious materials can be significantly influenced by M/P molar ratio, addition of setting retarder, water content, fly ash replacement of magnesia and aggregate usage. Therefore, the formulation of MKPC based materials is optimized in terms of workability, compressive strength, and cost consideration. With optimized formulation, MKPC mortars show high early compressive and flexural strength, superior bond strength to ordinary Portland cement mortar/concrete substrate, and low drying shrinkage. Undoubtedly, the mechanical properties of this cement is closely related to its inner composition and microstructure. The microstructure examination shows that the phase assemblage and the morphology characteristics of MKPC paste vary with the different formulae. In the formulation with lower M/P ratio of 2, KH2PO4 residues can be found in a flat, smooth, and bulky mass form. The reaction product MgKPO4·6H2O, can be observed as acicular crystal habit with large aspect ratio of 30. With the increase of M/P ratio

  12. Comparative study of electronic structure and charge transport in isostructural cuprates YBa2Cu3O7 and PrBa2Cu3O7

    International Nuclear Information System (INIS)

    Kormilets, V.I.

    1997-01-01

    The self-consistent calculations of electronic structure and charge distribution in YBa 2 Cu 3 O 7 and PrBa 2 Cu 3 O 7 crystals were performed by the method of linear muffin-tin orbitals with full potentials (FP-LMTO). It is revealed that the substitution of Pr for Y results in the charge transfer from a CuO chain to a CuO 2 plane. In its turn, this results in partial innihilation of holes responsible for superconductivity. The effect is analogous to that arisen from the removal of oxygen atoms from CuO chains. It is shown that the degree of covalence of 1-2-3 compounds being considered constitutes and essential value and decreases with pr substitution for Y

  13. Iron-phosphate-based chemically bonded phosphate ceramics for mixed waste stabilization

    International Nuclear Information System (INIS)

    Wagh, A.S.; Jeong, S.Y.; Singh, D.

    1997-01-01

    In an effort to develop chemically bonded phosphate ceramics for mixed waste stabilization, a collaborative project to develop iron-phosphate based ceramics has been initiated between Argonne National Laboratory and the V. G. Khlopin Radium Institute in St. Petersburg, Russia. The starter powders are oxides of iron that are generated as inexpensive byproduct materials in the iron and steel industry. They contain iron oxides as a mixture of magnetite (Fe 3 O 4 ) and haematite (Fe 2 O 3 ). In this initial phase of this project, both of these compounds were investigated independently. Each was reacted with phosphoric acid solution to form iron phosphate ceramics. In the case of magnetite, the reaction was rapid. Adding ash as the waste component containing hazardous contaminants resulted in a dense and hard ceramic rich in glassy phase. On the other hand, the reaction of phosphoric acid solution with a mixture of haematite and ash waste contaminated with cesium and americium was too slow. Samples had to be molded under pressure. They were cured for 2-3 weeks and then hardened by heating at 350 degrees C for 3 h. The resulting ceramics in both cases were subjected to physical tests for measurement of density, open porosity, compression strength, phase analyses using X-ray diffraction and differential thermal analysis, and leaching tests using toxicity characteristic leaching procedure (TCLP) and ANS 16.1 with 7 days of leaching. Using the preliminary information obtained from these tests, we evaluated these materials for stabilization of Department of Energy's mixed waste streams

  14. Effects of nitrate, fulvate, phosphate, phthalate, salicylate and catechol on the sorption of uranyl onto SiO2. A comparative study

    International Nuclear Information System (INIS)

    Zhang Hongxia; Wen Chuanxi; Tao Zuyi; Wu Wangsuo

    2011-01-01

    We have performed a large number of batch sorption experiments of uranyl onto SiO 2 and examined the effects of nitrate or ionic strength, phosphate, fulvic acid(FA), phthalic acid (PH), salicylic acid (SA), and catechol (CA) on the uranyl sorption onto SiO 2 . Three sorption edges and three sorption isotherms at ionic strengths 0.05, 0.1, and 0.5 mol/L KNO 3 were used to investigate the effect of ionic strength or nitrate on the sorption and the Langmuir, Freundlich, and Dubinin-Radushkevich models are used to simulate the sorption isotherms, respectively. Five sorption edges in the presence of phosphate, FA, PH, SA, and CA were compared with that in the absence of complexing ligand. The results suggest that the effect of complexation of uranyl with nitrate on the uranyl sorption can be negligible and the sorption can be described Freundlich and D-R model very well. The positive effect of phosphate on the uranyl sorption was found, though the extent of effect was decreased with increasing pH. The positive effect and the negative effect of FA on the uranyl sorption were found at low pH and high pH ranges, respectively. The sorption edge of uranyl sorption remained unaffected in the presence of PH in the pH 2-10. In the presence of SA, the no effect and the negative effect on the uranyl sorption were, respectively, found at low pH and high pH ranges. The negative effect of CA on the uranyl sorption was found in the pH 2-10. (author)

  15. Co3(PO4)2·4H2O

    Science.gov (United States)

    Lee, Young Hoon; Clegg, Jack K.; Lindoy, Leonard F.; Lu, G. Q. Max; Park, Yu-Chul; Kim, Yang

    2008-01-01

    Single crystals of Co3(PO4)2·4H2O, tricobalt(II) bis­[ortho­phosphate(V)] tetra­hydrate, were obtained under hydro­thermal conditions. The title compound is isotypic with its zinc analogue Zn3(PO4)2·4H2O (mineral name hopeite) and contains two independent Co2+ cations. One Co2+ cation exhibits a slightly distorted tetra­hedral coordination, while the second, located on a mirror plane, has a distorted octa­hedral coordination environment. The tetra­hedrally coordinated Co2+ is bonded to four O atoms of four PO4 3− anions, whereas the six-coordinate Co2+ is cis-bonded to two phosphate groups and to four O atoms of four water mol­ecules (two of which are located on mirror planes), forming a framework structure. In addition, hydrogen bonds of the type O—H⋯O are present throughout the crystal structure. PMID:21200978

  16. Regularities of the extraction of rare earth elements with triisoamyl phosphate

    International Nuclear Information System (INIS)

    Danilov, N.A.; Korpusov, G.V.; Utkina, O.V.; Pogorel'skaya, S.A.

    1988-01-01

    A study was made on practically important regularities of rare earth element (REE) extraction by triisoamyl phosphate (TiAP): isotherms of REE extraction, effect of REE and salting-out agents concentrations in aqueous phase on REE distribution and separation coefficients, effect of HNO 3 concentration and others. The data obtained show, that TiAP is the typical representative of neutral organophosphoric compounds, and its extraction properties are close to those of TBP. The third phase doesn't form during REE nitrate extraction by TiAP solutions in saturated hydrocarbons of any concentration. High selectivity is not observed during separation of cerium subgroup REE by TiAP. TiAP losses are lower than those of TBP due to lower TiAP solubility in water

  17. Synthesis and characterization of BaAl{sub 2}O{sub 4}:Eu{sup 2+} co-doped with different rare earth ions

    Energy Technology Data Exchange (ETDEWEB)

    Lephoto, M.A. [Department of Physics, University of the Free State, Private bag X 13, Phuthaditjaba 9866, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Ntwaeaborwa, O.M., E-mail: ntwaeab@ufs.ac.za [Department of Physics, University of the Free State, Private bag X 13, Phuthaditjaba 9866, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Pitale, Shreyas S.; Swart, H.C. [Department of Physics, University of the Free State, Private bag X 13, Phuthaditjaba 9866, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth, ZA 6031 (South Africa); Mothudi, B.M. [Department of Physics, University of South Africa, P.O Box 392, Pretoria, ZA 6031 (South Africa)

    2012-05-15

    Combustion method was used in this study to prepare BaAl{sub 2}O{sub 4}:Eu{sup 2+} phosphors co-doped with different trivalent rare-earths (Re{sup 3+}=Dy{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, Sm{sup 3+}, Ce{sup 3+}, Er{sup 3+}, Pr{sup 3+} and Tb{sup 3+}) ions at an initiating temperature of 600 Degree-Sign C. The phosphors were annealed at 1000 Degree-Sign C for 3 h. As confirmed from the X-ray diffraction (XRD) data, both as prepared and post annealed samples crystallized in the well known hexagonal structure of BaAl{sub 2}O{sub 4}. All samples exhibited bluish-green emission associated with the 4f{sup 6}5d{sup 1}{yields}4f{sup 7} transitions of Eu{sup 2+} at {approx}500 nm. Although the highest intensity was observed from Er{sup 3+} co-doping, the longest afterglow (due to trapping and detrapping of charge carriers) was observed from Nd{sup 3+} followed by Dy{sup 3+} co-doping. The traps responsible for the long afterglow were studied using thermoluminescence (TL) spectroscopy.

  18. Ca doping of TSMTG-YBa2Cu3O7-δ/Y2BaCuO5 composites

    International Nuclear Information System (INIS)

    Delorme, F.; Harnois, C.; Monot-Laffez, I.; Marinel, S.

    2002-01-01

    Calcium doped YBa 2 Cu 3 O 7-δ /Y 2 BaCuO 5 bulk samples have been synthesised by the top-seeding-melt-texture growth (TSMTG) process up to 1 wt.% of CaCO 3 . Calcium additions up to 0.25 wt.% of CaCO 3 do not change the decomposition temperature whereas additions of 1 wt.% of CaCO 3 lead to an increase of the decomposition temperature of about 10 deg. C. This difference is not important enough to change the thermal cycle used to process YBa 2 Cu 3 O 7-δ undoped bulk samples. Microstructure studies show that no precursor or secondary phases containing calcium are present in the samples. Energy dispersive spectroscopy analyses have shown that Ca is present both in the YBa 2 Cu 3 O 7-δ matrix and the Y 2 BaCuO 5 particles. The position of the calcium atoms in the superconducting matrix is discussed. The calcium doped samples present slightly depressed critical temperatures but drastically depressed critical current densities

  19. Spectroscopic properties of highly Nd-doped lead phosphate glass

    Energy Technology Data Exchange (ETDEWEB)

    Novais, A.L.F. [Instituto de Física, Universidade Federal de Alagoas, Grupo de Fotônica e Fluidos Complexos, 57072-970 Maceió, AL (Brazil); Dantas, N.O. [Laboratório de Novos Materiais Isolantes e Semicondutores (LNMIS), Instituto de Física, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Guedes, I. [Departamento de Física, Universidade Federal do Ceará, Campus do PICI, Caixa Postal 6030, 60455-760 Fortaleza, CE (Brazil); Vermelho, M.V.D., E-mail: vermelho@fis.ufal.br [Instituto de Física, Universidade Federal de Alagoas, Grupo de Fotônica e Fluidos Complexos, 57072-970 Maceió, AL (Brazil)

    2015-11-05

    The spectroscopic characteristics of highly Nd{sup 3+}-doped lead phosphate glasses (xNd:Pb{sub 3}(PO{sub 4}){sub 2}) have been investigated. The X-ray spectra show that the matrices are glassy up to 25 wt% of Nd{sup 3+} doping. From the Judd–Ofelt analysis we observe that while the Ω{sub (2)} parameter remains constant indicating that the 4f{sup N} and 4f{sup N−1}5 d{sup 1} configurations are not affected by the Nd{sup 3+} doping, the behavior of both Ω{sub (4)} and Ω{sub (6)} changes for 15 wt% of Nd{sup 3+} doping. The reduction of the Ω{sub (6)} parameter is related to the increase of the covalence bonding between the ligands and the Nd{sup 3+} ions. At this particular concentration, the radiative lifetime has a four-fold enhancement. Such behaviors are likely to be related to a modification in the glass structure for high Nd{sup 3+} concentrations. - Graphical abstract: Highly doped lead-phosphate glass matrix, with nominal concentration of up to 25 wt%, maintain the spectroscopic properties without deterioration. The analysis concerning the point of view of Nd{sup 3+} ions showed that high concentrations only affects the rare earth electronic charge density distribution. - Highlights: • Spectroscopic characterization of Nd{sub 2}O{sub 3} highly doped lead phosphate glasses. • Phosphate glass doped with Nd{sup 3+} for applications in photonic devices. • Judd–Ofelt analysis in phosphate glasses doped with Neodymium.

  20. A study on artificial rare earth (RE2O3) based neutron absorber.

    Science.gov (United States)

    Kim, Kyung-O; Kyung Kim, Jong

    2015-11-01

    A new concept of a neutron absorption material (i.e., an artificial rare earth compound) was introduced for criticality control in a spent fuel storage system. In particular, spent nuclear fuels were considered as a potential source of rare earth elements because the nuclear fission of uranium produces a full range of nuclides. It was also found that an artificial rare earth compound (RE2O3) as a High-Level Waste (HLW) was naturally extracted from pyroprocessing technology developed for recovering uranium and transuranic elements (TRU) from spent fuels. In this study, various characteristics (e.g., activity, neutron absorption cross-section) were analyzed for validating the application possibility of this waste compound as a neutron absorption material. As a result, the artificial rare earth compound had a higher neutron absorption probability in the entire energy range, and it can be used for maintaining sub-criticality for more than 40 years on the basis of the neutron absorption capability of Boral™. Therefore, this approach is expected to vastly improve the efficiency of radioactive waste management by simultaneously keeping HLW and spent nuclear fuel in a restricted space. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Crystal structure of Nd4Cu2O7

    International Nuclear Information System (INIS)

    Pederzolli, D.R.; Attfield, J.P.

    1998-01-01

    The structure of Nd 4 Cu 2 O 7 (A2/m, a = 8.449 A, b = 3.759 A, c = 12.601 A, β = 109.57 ), prepared by topotactic reduction of the high-T c superconductor parent phase Nd 2 CuO 4 , has been determined from time-of-flight neutron powder diffraction data revealing a new oxygen vacancy-ordered arrangement containing cooperatively distorted Cu 2 O 3 planes in which 2- and 4- coordinate Cu - sites are present. (orig.)

  2. Synthesis of binary condensed cesium-manganese phosphates in melts of polyphosphoric acids

    International Nuclear Information System (INIS)

    Guzeeva, L.S.; Tananaev, I.V.

    1988-01-01

    Cuts of Cs 2 O-MnO 2 -P 2 O 5H2 O system are investigated within 150 - 400 d egC temperature interval at P three initial relations: Mn(n), equal to 5; 7.5; 10 and P constant relation, Mn (n), equal to 15. It is shown, that interaction of manganese and cesium oxides with melts of polyphosphoric acids within 150 - 400 d egC temperature interval leads to release of three types of binary condenced phosphates of trivalent manganese and cesium: Cs 2 MnH 3 (P 2 O 7 ) 2 diphosphate, CsMnHP 3 O 10 triphosphate, Cs 3 Mn 3 (P 6 O-1 8 ) 2 cyclohexaphosphate and CsMnP 3 O 9 binary cyclotriphosphate of bivalent manganese. The released compounds are characterized by chemical, roentgenophase analyses, IR-spectrometry and thermogravimetry

  3. Electronic structure of layered ferroelectric high-k titanate La2Ti2O7

    DEFF Research Database (Denmark)

    Atuchin, V. V.; Gavrilova, T. A.; Grivel, Jean-Claude

    2009-01-01

    The electronic structure of binary titanate La2Ti2O7 has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La2Ti2O7 are determined as alpha(Ti) = 872...

  4. Tricalcium phosphate based resorbable ceramics: Influence of NaF and CaO addition

    Energy Technology Data Exchange (ETDEWEB)

    Seeley, Zachary; Bandyopadhyay, Amit [W. M. Keck Biomedical Materials Research Lab, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 (United States); Bose, Susmita [W. M. Keck Biomedical Materials Research Lab, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 (United States)], E-mail: sbose@wsu.edu

    2008-01-10

    Resorbable bioceramics have gained much attention due to their time-varying mechanical properties in-vivo. Implanted ceramics degrade allowing bone in-growth and eventual replacement of the artificial material with natural tissue. Calcium phosphate based materials have caught the most significant attention because of their excellent biocompatibility and compositional similarities to natural bone. Doping these ceramics with various metal ions has significantly influenced their properties. In this study, tricalcium phosphate (TCP) compacts were fabricated via uniaxial compression with five compositions: (i) pure TCP, (ii) TCP with 2.0 wt.% NaF, (iii) TCP with 3.0 wt.% CaO, (iv) TCP with a binary of 2.0 wt.% NaF and 0.5 wt.% Ag{sub 2}O, and (v) TCP with a quaternary of 1.0 wt.% TiO{sub 2}, 0.5 wt.% Ag{sub 2}O, 2.0 wt.% NaF, and 3.0 wt.% CaO. These compacts were sintered at 1250 deg. C for 4 h to obtain dense ceramic structures. Phase analyses were carried out using X-ray diffraction. The presence of NaF in TCP improved densification and increased compression strength from 70 ({+-} 25) to 130 ({+-} 40) MPa. Addition of CaO had no influence on density or strength. Human osteoblast cell growth behavior was studied using an osteoprecursor cell line (OPC 1) to assure that the biocompatibility of these ceramics was not altered due to the dopants. For long-term biodegradation studies, density, weight change, surface microstructure, and uniaxial compression strength were measured as a function of time in a simulated body fluid (SBF). Weight gain in SBF correlated strongly with precipitation viewed in the inter-connected pores of the samples. After 3 months in SBF, all samples displayed a reduction in strength. NaF, CaO and the quaternary compositions maintained the most steady strength loss under SBF.

  5. Phosphatic Permian rocks of the Adobe Range, Nevada, and their environment of deposition

    Science.gov (United States)

    Ketner, Keith Brindley

    1979-01-01

    Permian sedimentary rocks in the Adobe range, northern Nevada, are phosphatic, and although the particles of phosphate are relatively more disseminated, they closely resemble the rocks of the Phosphoria Formation. In the northern Adobe Range, where the entire Permian sequence is approximately correlative with the Phosphoria Formation, it is 200 m thick and averages 1.7 percent P2O5 . In the southern Adobe Range, the Permian sequence is more than 1,700 m thick, and the upper half which is roughly correlative with the Phosphoria Formation averages more than 2 percent P2O5. Some thin beds in rocks of Permian age contain more than 20 percent P2O5. Phosphatic rocks of the Adobe Range were deposited in shallow water among islands in the western part of the epicontinental Phosphoria sea. The continental margin and the open ocean lay far to the west. At the same time, the Phosphoria Formation was being deposited in the eastern and central parts of the Phosphoria sea. Theories based on the work of Kasakov done in 1937 relating phosphate deposition directly to sites of upwelling oceanic waters are questioned. Nondeposition of diluent materials such as detritus and carbonate is probably of more importance in producing phosphate in economic concentrations than is geographic position with respect to upwelling waters.

  6. Dosimetric properties of Li2 B4 O7: Tm pellets

    International Nuclear Information System (INIS)

    Rzyski, B.M.; Morato, S.P.

    1987-10-01

    Pellets produced out of thulium doped lithium tetraborate, (Li 2 B 4 O 7 :Tm), for thermoluminescent, (TL), dosimetry present low sensibility to environment conditions. Humidity, ambiet temperature, fading and handling during TL reading have almost no influence on the TL properties of the pellets prepared according the receipt given in this paper. The structure of the TL glow curve for the irradiated Li 2 B 4 O 7 : Tm pellet is rather simple and the TL response is linear in the range of 3x10 -4 to 7x10 2 Gy. The dosimetric properties of Li 2 B 4 O 7 : Tm in pellet form makes it a competitor with other TL phosphors. (author) [pt

  7. Uranium and thorium based phosphate matrix: synthesis, characterizations and lixiviation; Matrices a base de phosphate d'uranium et de thorium: syntheses, caracterisations et lixiviation

    Energy Technology Data Exchange (ETDEWEB)

    Dacheux, N

    1995-03-01

    In the framework of the search for a ceramic material usable in the radioactive waste storage, uranium and thorium phosphates have been investigated. Their experimental synthesis conditions have been entirely reviewed, they lead to the preparation of four new compounds: U(UO{sub 2})(PO{sub 4}){sub 2}, U{sub 2}O(PO{sub 4}){sub 2}, UCIPO{sub 4}, 4H{sub 2}O, and Th{sub 4}(PO{sub 4}){sub 4}P{sub 2}O{sub 7}. Experimental evidenced are advanced for non existent compounds such as: U{sub 3}(PO{sub 4}){sub 4}, U{sub 2}O{sub 3}P{sub 2}O{sub 7} and Th{sub 3} (PO{sub 4}){sub 4}. Characterization by several techniques (X-rays and neutron powder diffractions, UV-Visible and Infra-red spectroscopies, XPS,...) were performed. The ab initio structure determination of U(UO{sub 2})(PO{sub 4}){sub 2} has been achieved by X-rays and refined by neutron diffractions. Through its physico-chemical analysis, we found that this compound was a new mixed valence uranium phosphate in which U{sup 4+} and UO{sub 2}{sup 2+} ions are ordered in pairs along parallel chains according to a new type of arrangement. Reaction mechanism, starting from UCIPO{sub 4}, 4H{sub 2}O and based on redox processes of uranium in solid state was set up. From two main matrices U(UO{sub 2})(PO{sub 4}){sub 2} and Th{sub 4}(PO{sub 4}){sub 4}P{sub 2}O{sub 7}, solid solutions were studied. They consist of replacement of U(IV) by Th(IV) and reversely. The leaching tests on pure, loaded and doped matrices were performed in terms of storage time, pH of solutions, and determined by the use of solids labelled with {sup 230}U or by the measurement of uranyl concentration by Laser-Induced Time-Resolved Spectro-fluorimetry. Average concentration of uranium in the liquid phase is around 10{sup -4} M to 10{sup -6} M. Taking into account the very low solubilities of the studied phosphate ceramics, we estimated their chemical performances promising as an answer to the important nuclear waste problem, if we compare them to the glasses

  8. Uso de Fosfato Bicálcico Granulado Sobre o Desempenho e Mineralização Óssea de Frangos de Corte Effect of Granulated Dicalcium Phosphate on the Performance and Bone Mineralization in Broilers

    Directory of Open Access Journals (Sweden)

    OM Junqueira

    2001-01-01

    Full Text Available O objetivo do experimento foi avaliar os efeitos do tamanho da partícula do fosfato bicálcico (fina ou granulada e dos níveis de fósforo total sobre o desempenho de frangos de corte e sobre os teores de cálcio, fósforo e magnésio dos ossos. O delineamento experimental utilizado foi o inteiramente casualizado em esquema fatorial 3x2 com 3 níveis de fósforo total (0,5%; 0,6% e 0,7% e duas granulometrias de fosfato bicálcico (fina e granulada. Foram utilizados 300 pintos de corte com um dia de idade, machos, da linhagem Cobb, alojados em baterias metálicas em 6 tratamentos com 5 repetições de 10 aves, totalizando 30 gaiolas dispostas em 6 baterias de 5 andares cada. Os resultados demonstraram que o uso do fosfato granulado resultou em melhor desempenho dos animais. Aves alimentadas com o nível de 0,5% de fósforo total apresentaram o pior desempenho, sendo que o nível de 0,6% proporcionou melhor desempenho das aves. As diferentes granulometrias do fosfato, não diferiram estatisticamente quanto a percentagem de matéria mineral, cálcio, fósforo e magnésio nos ossos.The objective of the experiment was to evaluate the effects of particle size of dicalcium phosphate (fine or granulated and of the levels of total phosphorus on the performance of broilers and levels of calcium, phosphorus and magnesium of the bones. Three hundred one-day chicks, males, Cobb strain, were used in an experimental design involving six treatments in a factorial arrangement 2x3 (2 particles size of dicalcium phosphate and 3 phosphorus levels of 0,5%, 0,6% e 0,7%. It was concluded that the addition of granulated dicalcium phosphate resulted in a better performance. The level of 0,5% total phosphorus depressed body weight gain, feed intake and feed conversion and level 0,6% showed better performance. Total bone ash and bone calcium were not affected by treatments, however, better bone phosphorus was found when the broilers received the diet with 0,7% total

  9. The Influence of Phosphate Buffer on the Formation of N-Nitrosodimethylamine from Dimethylamine Nitrosation

    Directory of Open Access Journals (Sweden)

    Long Xu

    2013-01-01

    Full Text Available Buffer solutions were widely used for almost all the investigations concerning N-nitrosodimethylamine (NDMA, a member of powerful mutagenic and carcinogenic compounds which are ubiquitous in the environment. However, whether or how the buffer matrixes influence NDMA formation is still unknown. The effect of buffer solutions on NDMA formation from the nitrosation of dimethylamine (DMA by nitrite (NaNO2 was investigated at pH 6.4 in four kinds of buffer solutions, that is, Na2HPO4/C6H8O7, Na3(C6H5O7/C6H8O7, NaH2PO4/NaOH, and NaH2PO4/Na2HPO4. Our observations demonstrate an unexpected inhibitory effect of the buffer solutions on NDMA formation and the phosphate buffer plays a more significant role in inhibiting NDMA formation compared to the citrate buffer. Moreover, the amount of the phosphate in the buffer was also found to greatly impact the formation of NDMA. A further investigation indicates that it is the interaction between NaH2PO4 and reactant NaNO2 rather than DMA that leads to the inhibitory effect of phosphate buffer during the DMA nitrosation reaction. This study expands the understanding of the influence of buffer solution on nitrosamines formation through the nitrosation pathway and further gives a hint for water plants to reduce the formation of nitrosamines.

  10. Colossal thermoelectric power factor in K7/8RhO2

    KAUST Repository

    Saeed, Yasir

    2012-04-12

    The thermoelectric properties of the layered oxides KxRhO 2 (x = 1/2 and 7/8) are investigated by means of the electronic structure, as determined by ab inito calculations and Boltzmann transport theory. In general, the electronic structure of K xRhO 2 is similar to Na xCoO 2, but with strongly enhanced transport. K 7/8RhO 2 exceeds the ultrahigh power factor of Na 0.88CoO 2 reported previously by more than 50%. The roles of the cation concentration and the lattice parameters in the transport properties in this class of compounds are explained. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Investigation into complexing in Re7-H3O+-SO42--H2O system

    International Nuclear Information System (INIS)

    Sinyakova, G.S.

    1979-01-01

    Using the methods of spectrophotometry and conductometry it is shown, that in the ReO 4 - -H 3 O + -SO 4 2- -H 2 O system interaction between rhenium (7) and sulfuric acid takes place in a wide concentration range. In low-acid solutions at pH 2.0-0.9 rhenium(7) complex with proton is formed at the ratio of 1:1 with lgK 1 =3.30+-0.02. In 1-10 mol. sulfuric acid observed is consecutive complexing at the rhenium(7) - sulfuric acid ratio in the complex of 1:1 and 1:2 respectively with lgK 2 =0.93+-0.13 and lgK 3 =0.34+-0.03. At the background of concentrated perchloric acid rhenium (7) and sodium sulfate form two complex compounds at rhenium (7) - sodium sulfate ratio of 1:1 and 1:2 with lgK 1 =1.86+-0.02 and lgK 2 =2.35+-0.03

  12. Uranium, thorium and potassium contents and radioactive equilibrium states of the uranium and thorium series nuclides in phosphate rocks and phosphate fertilizers

    Energy Technology Data Exchange (ETDEWEB)

    Komura, K; Yanagisawa, M; Sakurai, J; Sakanoue, M

    1985-10-01

    Uranium, thorium and potassium contents and radioactive equilibrium states of the uranium and thorium series nuclides have been studied for 2 phosphate rocks and 7 phosphate fertilizers. Uranium contents were found to be rather high (39-117 ppm) except for phosphate rock from Kola. The uranium series nuclides were found to be in various equilibration states, which can be grouped into following three categories. Almost in the equilibrium state, 238U approximately 230Th greater than 210Pb greater than 226Ra and 238U greater than 230Th greater than 210Pb greater than 226Ra. Thorium contents were found to be, in general, low and appreciable disequilibrium of the thorium series nuclides was not observed except one sample. Potassium contents were also very low (less than 0.3% K2O) except for complex fertilizers. Based on the present data, discussions were made for the radiation exposure due to phosphate fertilizers.

  13. Competição de fertilizantes fosfatados para o trigo Influence of phosphate sources on wheat production

    Directory of Open Access Journals (Sweden)

    H. Garcia Blanco

    1962-01-01

    Full Text Available Um experimento de adubação para cultura de trigo, estudando diversos adubos fosfatados, é aqui relatado. Foram empregadas doses crescentes de 90 e 180 kg/ha de P2O5, em presença e em ausência de calcário. Os fosfatos utilizados, sempre acompanhados de nitrogênio e potássio, foram; superfosfato simples, superfosfato triplo, fosforita de Olinda, fosfato Alvorada (apatita do Morro do Serrote e apatita de Araxá. O ensaio foi conduzido no município de Avaré, Estado de São Paulo, em solo do arenito de Botucatu. Os resultados mostraram reação significativa para o fósforo, sòmente quando se usaram os superfosfatos simples e triplo, especialmente para êste último. Por sua vez, parcelas sem calcário não diferiram significativamente, na produção, daquelas que receberam calagem.Results from field experiment are presented in this paper concerning phosphorus fertilization on wheat. Two rates of phosphorus, 90 and 180 kg/ha of P2O5, were compared in presence and absence of lime. Triple superphosphate, ordinary superphosphate and three Brazilian rock phosphates, i.e. fosforita de Olinda, fosfato Alvorada and fosfato Araxá, were utilized as phosphorus sources, with general application of nitrogen and potassium. The experiment was located on a soil classified as Arenito de Bo-tucatu, at Avaré, São Paulo State. The favorable effect of both types of superphosphate in increasing the yeld was highly significant, while the use of three rock phosphates phomoted no significant increase on wheat production, as compared to the checks, without phosphorus. Use of lime had no effect on grain production.

  14. Metals concentration in phosphogypsum and phosphate fertilizers produced in Brazil using INAA

    International Nuclear Information System (INIS)

    Le Bourlegat, Fernanda M.; Saueia, Catia H.R.; Mazzilli, Barbara P.; Favaro, Deborah I.T.

    2009-01-01

    Phosphogypsum is obtained by wet reaction of the igneous phosphate rock with concentrated sulphuric acid, giving as final product phosphoric acid and dihydrated calcium sulphate (CaSO 4 .2H 2 O) as by-product. It may contain high quantities of P 2 O 5 , trace metals and radionuclides of U and Th series. Phosphogypsum worldwide production on 2006 was estimated in 170 million tons. All the countries that produce phosphate fertilizers by wet process are facing the same problem of finding solutions for the safe application of phosphogypsum, in order to minimize the impact caused by the disposal of large amounts of this by-product. Phosphogypsum can be used in agriculture as a soil amendment; however, for its safe application the concentration of the impurities present and their behaviour in the environment should be better understood. The radiological characterization has been extensively studied in the last decade, but there are few studies about the metals concentration in phosphogypsum. This work intends to determine the concentration of metals (Ba, Co, Cr, Fe, Hf, Na, Sc, Ta, Th, U, Zn e Zr) and rare earth elements (REE) present in phosphogypsum produced in Brazil and to compare the results with those found in the phosphate fertilizers commonly commercialized. The technique used for the determination of the metals was instrumental neutron activation analysis (INAA). (author)

  15. Synthesis and Electrocatalytic Activity of Ammonium Nickel Phosphate, [NH4]NiPO4·6H2O, and β-Nickel Pyrophosphate, β-Ni2P2O7: Catalysts for Electrocatalytic Decomposition of Urea.

    Science.gov (United States)

    Meguerdichian, Andrew G; Jafari, Tahereh; Shakil, Md R; Miao, Ran; Achola, Laura A; Macharia, John; Shirazi-Amin, Alireza; Suib, Steven L

    2018-02-19

    Electrocatalytic decomposition of urea for the production of hydrogen, H 2, for clean energy applications, such as in fuel cells, has several potential advantages such as reducing carbon emissions in the energy sector and environmental applications to remove urea from animal and human waste facilities. The study and development of new catalyst materials containing nickel metal, the active site for urea decomposition, is a critical aspect of research in inorganic and materials chemistry. We report the synthesis and application of [NH 4 ]NiPO 4 ·6H 2 O and β-Ni 2 P 2 O 7 using in situ prepared [NH 4 ] 2 HPO 4 . The [NH 4 ]NiPO 4 ·6H 2 O is calcined at varying temperatures and tested for electrocatalytic decomposition of urea. Our results indicate that [NH 4 ]NiPO 4 ·6H 2 O calcined at 300 °C with an amorphous crystal structure and, for the first time applied for urea electrocatalytic decomposition, had the greatest reported electroactive surface area (ESA) of 142 cm 2 /mg and an onset potential of 0.33 V (SCE) and was stable over a 24-h test period.

  16. Uptake of some lanthanides on γ-zirconium phosphate-phosphite and its 1,10-phenanthroline and 2,2-bipyridyl intercalated products

    International Nuclear Information System (INIS)

    Shakshooki, S.K.; El Hanash, H.B.; El-Mehdawi, R.M.; El-Mellah, M.A.; Arafa, E.A.; Bejey, A.M.

    1999-01-01

    γ-zirconium phosphate-phosphite, γ-Zr x PO 4 x H 2 PO 3 x 2H 2 O, (γ-ZrPP), was prepared and characterized. Direct treatment of γ-zirconium phosphate-phosphite with an ethanol solution of 0.1M 1,10-phenanthrolin and 2,2'-bipyridyl gave the well defined composites, γ-Zr x PO 4 x H 2 PO 3 (phen) 0.15 x H 2 O and γ-Zr x PO 4 x H 2 PO 3 (bipy) 0.18 x 0.6H 2 O respectively. K d values of a mixture of lanthanide ions: La 3+ , Sm 3+ , Eu 3+ and Yb 3+ for the intercalated products and for γ-ZrPP in HNO 3 solution at room temperature and at pH 2 and 4 were determined by a radiotracer technique. 140 La, 152m Eu, 153 Sm and 175 Yb radioisotopes were used for the equilibration experiment using 500 μl (4.0 x 10 -5 mmole) each of the solutions of the tracers as a mixture in 7.5 M HNO 3 solution at the desired pH with 0.1 g of γ-ZrPP and of the intercalated products. The selectivity order was found to be dependent on the nature of the ligand and on the pH. The 2,2'-bipyridyl product possesses, at pH 2 in general, a high K d value, specially for Sm 3+ (9815.9) compared to that of the 1,10-phenanthrolin product (3375.5) and to γ-ZrPP (419.8). This could be attributed to partial deintercalation of the 2,2' -bipyridyl at pH 2 and increasing of ionogenic groups. (author)

  17. Perovskite-type La{sub 2}Ti{sub 2}O{sub 7} mesoporous photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Onozuka, K.; Kawakami, Y.; Imai, H.; Yokoi, T.; Tatsumi, T. [Chemical Resources Laboratory, Tokyo Institute of Technology, R1-10, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Kondo, J.N., E-mail: jnomura@res.titech.ac.jp [Chemical Resources Laboratory, Tokyo Institute of Technology, R1-10, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

    2012-08-15

    Crystalline particles of mesoporous La{sub 2}Ti{sub 2}O{sub 7}, a perovskite-type material, were prepared by hydrothermal synthesis at 210 Degree-Sign C in the presence of structure directing agent. Crystallization and simultaneous sintering occurred in the time course of the hydrothermal treatment, resulting in the improvement in crystallinity with a sacrifice of the decrease in surface area. The photocatalytic property was evaluated by hydrogen evolution from water with methanol sacrificial agent. The increase and the decrease of the material in crystallinity and surface area were responsible for the photocatalytic activity: the activity was improved by crystallization but the concurrent decrease in surface area (increase in size) of crystalline particles was disadvantageous. - Graphical abstract: A homogeneous mixture of La and Ti oxide with amorphous inorganic network was hydrothermally crystallized at low temperatures to a perovskite-type La{sub 2}Ti{sub 2}O{sub 7}. The small La{sub 2}Ti{sub 2}O{sub 7} particles with high crystallinity showed a potential as a photocatalyst for H{sub 2} evolution. Highlights: Black-Right-Pointing-Pointer Crystalline mesopourous La{sub 2}Ti{sub 2}O{sub 7} was prepared. Black-Right-Pointing-Pointer Hydrothermal treatment encouraged low temperature crystallization. Black-Right-Pointing-Pointer Small crystalline domain was advantageous to a photocatalytic reaction.

  18. Effects of chlorides on the hydration of 12CaO{center_dot}7Al2O3 solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Sango, H.; Miyakawa, T.; Yasue, T.; Arai, Y. [Nihon Univ., Tokyo (Japan). Faculty of Science and Engineering

    1995-01-01

    The purpose of this paper was to compare the hydration rate of C12A7ss and to study the effects of chlorides on the hydration products and the hydration rate of C12A7ss. In this paper, `C12A7ss` is a general term for C11A7{center_dot}Ca(OH)2, 11CaO{center_dot}7Al2O3{center_dot}CaF2 and 11CaO{center_dot}7Al2O3{center_dot}CaCl2. The hydration process and the hydration rate of 12CaO{center_dot}7Al2O3 solution (C12A7ss) with and without various chlorides (CaCl2, MgCl2, NaCl, NH4Cl and AlCl3) has been determined at 25{degree}C. Various C12A7ss were prepared in burning method. When C12A7ss with various chlorides are hydrated, 3CaO{center_dot} Al2O3{center_dot}CaCl2{center_dot}10H2O(Friedel`s salt) is formed as the primary hydrate. The hydration rate of C12A7ss is decreased by the coexistence of CaCl2, MgCl2, NaCl or NH4Cl except AlCl3. As a result, the setting time of C12A7ss is extended and the unhydrate exists for a long time comparatively. 14 refs., 7 figs., 1 tab.

  19. Activation analysis of rare-earth elements in opium and cannabis samples. [Neutron reactions

    Energy Technology Data Exchange (ETDEWEB)

    Henke, G [Muenster Univ. (Germany, F.R.). Inst. fuer Pharmazeutische Chemie

    1977-01-01

    Rare-earth concentrations in 65 Opium, Cannabis and Cannabis resin samples seized from various parts of the world were determined by destructive NAA. Because of the greater concentrations of Ca, P, K, Fe, Na and Si in plant materials, rare-earth elements were isolated after neutron irradiation and determined by gamma-spectrometry. The main steps of the method are: Preashing of 1 g Cannabis resin, 2.5 g Cannabis, or 7.5 g Opium, respectively, in quartz ampoules (5 h, 500 deg C). Neutron irradiation, 24 h at 5x10/sup 13/n cm/sup -2/sec/sup -1/. Cooling period 2-3 days. After addition of 0.1 ..mu..Ci /sup 139/Ce and rare-earth carriers wet ashing of irradiated samples with H/sub 2/SO/sub 4//HNO/sub 3/, followed by alternate addition of HNO/sub 3/ and H/sub 2/O/sub 2/ (30%). Precipitation and removal of silicates, precipitation of fluorides, precipitation of hydroxides. Dissolution of hydroxides in HCl. Extraction with di-(2-ethylhexyl)phosphate (DEHP)/toluene and twice back-extraction of rare earths, gamma-spectrometry of HCl phase. Due to sample activity and half-life of nuclides, three measurements were made on each sample: 2 days (for La, Sm, Gd, Ho, Er, Yb); 14 days (for Nd, Lu) and 30 days after irradiation (for Ce, Eu, Tb). Great variations in absolute element concentrations, but only small significant differences of rare earth concentration ratios were found, indicating inconsiderable biogeochemical fractionation. The mean values of these ratios correspond to the relative abundances of the rare earths in the upper continental earth's crust.

  20. Fabrication and properties of La2-xGdxHf2O7 transparent ceramics

    International Nuclear Information System (INIS)

    Wang, Zhengjuan; Zhou, Guohong; Zhang, Fang; Qin, Xianpeng; Ai, Jianping; Wang, Shiwei

    2016-01-01

    La 2-x Gd x Hf 2 O 7 (x=0–2.0) transparent ceramics were fabricated through vacuum sintering from nano-powders synthesized by a simple combustion method. The phase composition of the powders and final ceramics, the in-line transmittance, microstructures and density of the ceramics were investigated. With the increasing of Gd content, the ceramics maintained the cubic pyrochlore structure, and the lattice parameters decreased, whilst the densities increased linearly. All the ceramics were transparent. The highest in-line transmittance was 76.1% at 800 nm (x=1.2). With high density (7.91–8.88 g/cm 3 ) and effective atomic number, some of the La 2-x Gd x Hf 2 O 7 (x=0–2.0) transparent ceramics are promising candidates for scintillator hosts. - Highlights: • A new series of La 2-x Gd x Hf 2 O 7 transparent ceramics were fabricated by vacuum sintering using combustion-synthesized powders. • All the ceramics are transparent and the in-line transmittance can reach to 76.1% at 800 nm when x=1.2. • The Gd content has effects on the crystal structure, in-line transmittance, microstructures and densities of the ceramics. • With high density (7.91~8.88 g/cm3) and effective atomic number, some of the La2-xGdxHf2O7 transparent ceramics are promising candidates for scintillator hosts.

  1. Nano zinc phosphate coatings for enhanced corrosion resistance of mild steel

    International Nuclear Information System (INIS)

    Tamilselvi, M.; Kamaraj, P.; Arthanareeswari, M.; Devikala, S.

    2015-01-01

    Highlights: • Nano zinc phosphate coating on mild steel was developed. • Nano zinc phosphate coatings on mild steel showed enhanced corrosion resistance. • The nano ZnO increases the number of nucleating sites for phosphating. • Faster attainment of steady state during nano zinc phosphating. - Abstract: Nano crystalline zinc phosphate coatings were developed on mild steel surface using nano zinc oxide particles. The chemical composition and morphology of the coatings were analyzed by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The particles size of the nano zinc phosphate coating developed was also characterized by TEM analysis. Potentiodynamic polarization and electrochemical impedance studies were carried out in 3.5% NaCl solution. Significant variations in the coating weight, morphology and corrosion resistance were observed as nano ZnO concentrations were varied from 0.25 to 2 g/L in the phosphating baths. The results showed that nano ZnO particles in the phosphating solution yielded phosphate coatings of higher coating weight, greater surface coverage and enhanced corrosion resistance than the normal zinc phosphate coatings (developed using normal ZnO particles in the phosphating baths). Better corrosion resistance was observed for coatings derived from phosphating bath containing 1.5 g/L nano ZnO. The activation effect brought about by the nano ZnO reduces the amount of accelerator (NaNO 2 ) required for phosphating

  2. The Development of HfO2-Rare Earth Based Oxide Materials and Barrier Coatings for Thermal Protection Systems

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan James

    2014-01-01

    Advanced hafnia-rare earth oxides, rare earth aluminates and silicates have been developed for thermal environmental barrier systems for aerospace propulsion engine and thermal protection applications. The high temperature stability, low thermal conductivity, excellent oxidation resistance and mechanical properties of these oxide material systems make them attractive and potentially viable for thermal protection systems. This paper will focus on the development of the high performance and high temperature capable ZrO2HfO2-rare earth based alloy and compound oxide materials, processed as protective coating systems using state-or-the-art processing techniques. The emphasis has been in particular placed on assessing their temperature capability, stability and suitability for advanced space vehicle entry thermal protection systems. Fundamental thermophysical and thermomechanical properties of the material systems have been investigated at high temperatures. Laser high-heat-flux testing has also been developed to validate the material systems, and demonstrating durability under space entry high heat flux conditions.

  3. Analysis of low-field isotropic vortex glass containing vortex groups in YBa2Cu3O7-x thin films visualized by scanning SQUID microscopy

    NARCIS (Netherlands)

    Wells, Frederick S.; Pan, Alexey V.; Wang, X.; Fedoseev, Sergey A.; Hilgenkamp, Hans

    2015-01-01

    The glass-like vortex distribution in pulsed laser deposited YBa2Cu3O7-x thin films is observed by scanning superconducting quantum interference device microscopy and analysed for ordering after cooling in magnetic fields significantly smaller than the Earth's field. Autocorrelation calculations on

  4. Kinetic study of the thorium phosphate - diphosphate dissolution

    International Nuclear Information System (INIS)

    Dacheux, N.; Thomas, A.C.; Brandel, V.; Genet, M.

    2000-01-01

    The thorium phosphate-diphosphate Th 4 (PO 4 ) 4 P 2 O 7 (TPD) structure allows the replacement of large amounts of thorium by tetravalent actinides leading to the formation of solid solutions. This compound was obtained in powdered or sintered form after pressing at room temperature at 300-800 MPa then heating at 1250 deg. C for 10-30 hours. The resistance of this material to aqueous corrosion was determined by varying several parameters such as surface, leaching flow, acidity or temperature. It was thus possible to independently determine the influence of each parameter on the leaching rate provided that the saturation of the solution was not obtained. In acidic media, the partial order related to [H 3 O + ] was found to be in the 0.31-0.35 range while, in basic media, the partial order related to [OH - ] was almost the same (0.45). The activation energy (42 kJ/mol) was determined between 4 deg. C and 120 deg. C. Moreover, the addition of phosphate in the leachate slightly increased the TPD dissolution rate. When the saturation of the solution is reached, a gelatinous precipitate controls the thorium and phosphate concentrations. The complete characterization of this solid led to the proposed general formula Th 2 (PO 4 ) 2 (HPO 4 ). n H 2 O which conventional solubility product (at I = 0 M) is very low: K * S,0 10 -66.6±1.2 even in very acidic media. (authors)

  5. Static susceptibility and heat capacity studies on V{sub 3}O{sub 7}.H{sub 2}O{sub 7} nanobelts

    Energy Technology Data Exchange (ETDEWEB)

    Hellmann, I., E-mail: i.hellmann@ifw-dresden.d [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Zakharova, G.S.; Volkov, V.L. [Institute of Solid State Chemistry, Ural Division, Russian Academy of Sciences, Pervomaiskaya ul. 91, Yekaterinburg 620219 (Russian Federation); Taeschner, C.; Leonhardt, A.; Buechner, B.; Klingeler, R. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)

    2010-04-15

    V{sub 3}O{sub 7}.H{sub 2}O nanobelts were prepared by a hydrothermal method at 190 deg. C using V{sub 2}O{sub 5}.nH{sub 2}O gel and H{sub 2}C{sub 2}O{sub 4}.2H{sub 2}O as starting agents. The obtained nanobelts have diameters ranging from 40 to 70 nm with lengths up to several micrometers. Measurements of the static magnetic susceptibility and the specific heat show a discontinuous phase transition at around T=145 K, which separates two regions of paramagnetic behavior.

  6. Corrosion resistance and in-vitro bioactivity of BaO containing Na2O-CaO-P2O5 phosphate glass-ceramic coating prepared on 316 L, duplex stainless steel 2205 and Ti6Al4V

    Science.gov (United States)

    Edathazhe, Akhila B.; Shashikala, H. D.

    2018-03-01

    The phosphate glass with composition 11Na2O-15BaO-29CaO-45P2O5 was coated on biomedical implant materials such as stainless steel 316 L, duplex stainless steel (DSS) 2205 and Ti6Al4V alloy by thermal enamelling method. The structural properties and composition of glass coated substrates were studied by x-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive x-ray spectroscopy (EDS) analysis. The coatings were partially crystalline in nature with porous structure and pore size varied from micro to nanometer range. The polarization curve was obtained for uncoated and coated substrates from electrochemical corrosion test which was conducted at 37 °C in Hank’s balanced salt solution (HBSS). The corrosion resistance of 316 L substrate increased after coating, whereas it decreased in case of DSS 2205 and Ti6Al4V. The XRD and SEM/EDS studies indicated the bioactive hydroxyapatite (HAp) layer formation on all the coated surfaces after electrochemical corrosion test, which improved the corrosion resistance. The observed electrochemical corrosion behavior can be explained based on protective HAp layer formation, composition and diffusion of ions on glass coated surfaces. The in-vitro bioactivity test was carried out at 37 °C in HBS solution for 14 days under static conditions for uncoated and coated substrates. pH and ion release rate measurements from the coated samples were conducted to substantiate the electrochemical corrosion test. The lower ion release rates of Na+ and Ca2+ from coated 316 L supported its higher electrochemical corrosion resistance among coated samples. Among the uncoated substrates, DSS showed higher electrochemical corrosion resistance. Amorphous calcium-phosphate (ACP) layer formation on all the coated substrates after in-vitro bioactivity test was confirmed by XRD, SEM/EDS and ion release measurements. The present work is a comparative study of corrosion resistance and bioactivity of glass coated and uncoated

  7. Structural properties of the geometrically frustrated pyrochlore Tb2Ti2O7

    International Nuclear Information System (INIS)

    Han, Sang-Wook; Gardner, Jason S.; Booth, Corwin H.

    2004-01-01

    Although materials that exhibit nearest-neighbor-only antiferromagnetic interactions and geometrical frustration theoretically should not magnetically order in the absence of disorder, few such systems have been observed experimentally. One such system appears to be the pyrochlore Tb 2 Ti 2 O 7 . However, previous structural studies indicated that Tb 2 Ti 2 O 7 is an imperfect pyrochlore. To clarify the situation, we performed neutron powder diffraction (NPD) and x-ray absorption fine structure (XAFS) measurements on samples that were prepared identically to those that show no magnetic order. The NPD measurements show that the long-range structure of Tb 2 Ti 2 O 7 is well ordered with no structural transitions between 4.5 and 600 K. In particular, mean-squared displacements (u 2 's) for each site follow a Debye model with no offsets. No evidence for Tb/Ti site interchange was observed within an upper limit of 2%. Likewise, no excess or deficiency in the oxygen stoichiometry was observed, within an upper limit of 2% of the nominal pyrochlore value. Tb L III and Ti K-edge XAFS measurements from 20-300 K similarly indicate a well-ordered local structure. Other aspects of the structure are considered. We conclude that Tb 2 Ti 2 O 7 has, within experimental error, an ideal, disorder-free pyrochlore lattice, thereby allowing the system to remain in a dynamic, frustrated spin state to the lowest observed temperatures

  8. Leakage of Intracellular UV Materials of High Hydrostatic Pressure-Injured Escherichia Coli O157:H7 Strains in Tomato Juice

    Science.gov (United States)

    The effect of high hydrostatic pressure (HHP) treatment on inactivation, injury and recovery of Salmonella Enteritidis and Escherichia coli O157:H7 cocktail inoculated in tomato juice (pH 4.1) and phosphate buffer saline (PBS. pH 7.2) at 8.0 log CFU/ml and treated at 350, 400, 450 MPa for 20 min at ...

  9. The formation of crystals in glasses containing rare earth oxides

    Energy Technology Data Exchange (ETDEWEB)

    Fadzil, Syazwani Mohd [Pohang University of Science and Technology (POSTECH), Pohang (Korea, Republic of); Hrma, Pavel [Pohang University of Science and Technology (POSTECH), Pohang, South Korea and Pacific Northwest National Laboratory, Richland, Washington (United States); Crum, Jarrod [Pacific Northwest National Laboratory, Richland, Washington (United States); Siong, Khoo Kok; Ngatiman, Mohammad Fadzlee; Said, Riduan Mt [National University of Malaysia, Bandar Baru Bangi, Selangor (Malaysia)

    2014-02-12

    Korean spent nuclear fuel will reach the capacity of the available temporary storage by 2016. Pyroprocessing and direct disposal seems to be an alternative way to manage and reuse spent nuclear fuel while avoiding the wet reprocessing technology. Pyroprocessing produces several wastes streams, including metals, salts, and rare earths, which must be converted into stabilized form. A suitable form for rare earth immobilization is borosilicate glass. The borosilicate glass form exhibits excellent durability, allows a high waste loading, and is easy to process. In this work, we combined the rare earths waste of composition (in wt%) 39.2Nd{sub 2}O{sub 3}–22.7CeO{sub 2}–11.7La{sub 2}O{sub 3}–10.9PrO{sub 2}–1.3Eu{sub 2}O{sub 3}–1.3Gd{sub 2}O{sub 3}–8.1Sm{sub 2}O{sub 3}–4.8Y{sub 2}O{sub 3} with a baseline glass of composition 60.2SiO{sub 2}–16.0B{sub 2}O{sub 3}–12.6Na{sub 2}O–3.8Al{sub 2}O{sub 3}–5.7CaO–1.7ZrO{sub 2}. Crystallization in waste glasses occurs as the waste loading increases. It may produce complicate glass processing and affect the product quality. To study crystal formation, we initially made glasses containing 5%, 10% and 15% of La{sub 2}O{sub 3} and then glasses with 5%, 10% and 15% of the complete rare earth mix. Samples were heat-treated for 24 hours at temperatures 800°C to 1150°C in 50°C increments. Quenched samples were analyzed using an optical microscope, scanning electron microscope with energy dispersive spectroscopy, and x-ray diffraction. Stillwellite (LaBSiO{sub 5}) and oxyapatite (Ca{sub 2}La{sub 8}Si{sub 6}O{sub 26}) were found in glasses containing La{sub 2}O{sub 3}, while oxyapatite (Ca{sub 2}La{sub 8}Si{sub 6}O{sub 26} and NaNd{sub 9}Si{sub 6}O{sub 26}) precipitated in glasses with additions of mixed rare earths. The liquidus temperature (T{sub L}) of the glasses containing 5%, 10% and 15% La{sub 2}O{sub 3} were 800°C, 959°C and 986°C, respectively; while T{sub L} was 825°C, 1059°C and 1267°C for glasses

  10. Theoretical investigation of the Fermi surface of La2-xSrxCuO4 and YBa2Cu3O7

    International Nuclear Information System (INIS)

    Antonov, V.N.; Antonov, V.N.; Bar'yakhtar, V.G.

    1989-01-01

    The theoretical investigation of both the Fermi surface (FS) form and isoenergetic surfaces near the Fermi energy of La 2-x Sr x CuO 4 and YBa 2 Cu 3 O 7 is carried out by selfconsistent LMTO/method in an atomic sphere approximation. The FS of these compounds is established to have an essential two-dimensional character. The FS La 2 CuO 4 is a corrugated rounded box centered in Γ point. The FS YBa 2 Cu 3 O 7 consists of four plates: an electron ''cushion'' in Γ point and three embeded hole surfaces centered in S point. In this case the ''cushion'' and one of the hole surfaces are vigorously corrugated along the z-direction. A comparison between both the FS calculated theoretically of La 2 CuO 4 and YBa 2 Cu 3 O 7 and experimental data on electron-positron annihilation is carried out. The electron-rate maps and numerical results of various characteristics, i.e., plate areas, mean rates, mean squares of the rates, partial densities of states for each plate of the FS YBa 2 Cu 3 O 7 are given

  11. Electronic structure of layered ferroelectric high-k titanate Pr2Ti2O7

    Science.gov (United States)

    Atuchin, V. V.; Gavrilova, T. A.; Grivel, J.-C.; Kesler, V. G.; Troitskaia, I. B.

    2012-11-01

    The spectroscopic parameters and electronic structure of binary titanate Pr2Ti2O7 have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Pr2Ti2O7 have been determined as αTi=872.8 and αO=1042.3 eV. Variations of cation-anion bond ionicity have been discussed using binding energy differences ΔTi=(BE O 1s-BE Ti 2p3/2)=71.6 eV and ΔPr=BE(Pr 3d5/2)-BE(O 1s)=403.8 eV as key parameters in comparison with those of other titanium- and praseodymium-bearing oxides.

  12. Structural, magnetic and electronic properties of rare earth ternary oxides Li Ln(II) 2 Ln(III)O4

    International Nuclear Information System (INIS)

    Malki, M.

    1987-06-01

    Properties of a new class of rare earth ternary oxides Li Ln(II) 2 Ln(III)O 4 where Ln(II) is a divalent metal (Sr, Eu) and Ln(III) a trivalent rare earth (Eu, Gd, Dy, Er and Y). These orthorhombic compounds (type Li Eu 3 O 4 ) allow the study of many magnetic phenomena and their evolution in function of the nature of Ln(II) and Ln(III): diamagnetic ions Sr 2+ , Y 3+ ; isotrope magnetic ions: Eu 2+ , Gd 3+ and anisotrope magnetic ions Dy 3+ , Er 3+ . Magnetic and electric properties are obtained by classical techniques and from hyperfine interaction by Moessbauer spectroscopy. The possibility to use several Moessbauer resonance (nuclei Eu 151, Gd 155, Dy 161 and Er 166) completes informations obtained by the macroscopic study [fr

  13. Sc2[Se2O5]3: The First Rare-Earth Metal Oxoselenate(IV with Exclusively [Se2O5]2− Anions

    Directory of Open Access Journals (Sweden)

    Stefan Greiner

    2018-04-01

    Full Text Available The scandium oxodiselenate(IV Sc2[Se2O5]3 was synthesized via solid-state reactions between scandium sesquioxide (Sc2O3 and selenium dioxide (SeO2 with thallium(I chloride (TlCl as fluxing agent in molar ratios of 1:4:2. Evacuated fused silica ampoules were used as reactions vessels for annealing the mixtures for five days at 800 °C. The new scandium compound crystallizes in the triclinic space group P 1 ¯ with the lattice parameters a = 663.71(5 pm, b = 1024.32(7 pm, c = 1057.49(8 pm, α = 81.034(2°, β = 87.468(2°, γ = 89.237(2° and Z = 2. There are two distinct Sc3+ positions, which show six-fold coordination by oxygen atoms as [ScO6]9− octahedra (d(Sc–O = 205–212 pm. Three different [Se2O5]2− anions provide these oxygen atoms with their terminal ligands (Ot. Each of the six selenium(IV central atoms exhibit a stereochemically active lone pair of electrons, so that all [Se2O5]2− anions consist of two ψ1-tetrahedral [SeO3]2− subunits (d(Se–Ot = 164–167 pm, d(Se–Ob = 176–185 pm, ∢(O–Se–O = 93–104° sharing one bridging oxygen atom (Ob with ∢(Se–Ob–Se = 121–128°. The vibrational modes of the complex anionic [Se2O5]2− entities were characterized via single-crystal Raman spectroscopy.

  14. Double-ceramic-layer thermal barrier coatings based on La{sub 2}(Zr{sub 0.7}Ce{sub 0.3}){sub 2}O{sub 7}/La{sub 2}Ce{sub 2}O{sub 7} deposited by electron beam-physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Z.H. [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); He, L.M., E-mail: he_limin@yahoo.com [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Mu, R.D.; He, S.M.; Huang, G.H. [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Cao, X.Q., E-mail: xcao@ciac.jl.cn [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2010-03-15

    Double-ceramic-layer (DCL) thermal barrier coatings (TBCs) of La{sub 2}(Zr{sub 0.7}Ce{sub 0.3}){sub 2}O{sub 7} (LZ7C3) and La{sub 2}Ce{sub 2}O{sub 7} (LC) were deposited by electron beam-physical vapor deposition (EB-PVD). The composition, interdiffusion, surface and cross-sectional morphologies, cyclic oxidation behavior of DCL coating were studied. Energy dispersive spectroscopy and X-ray diffraction analyses indicate that both LZ7C3 and LC coatings are effectively fabricated by a single LZ7C3 ingot with properly controlling the deposition energy. The chemical compatibility of LC coating and thermally grown oxide (TGO) layer is unstable. LaAlO{sub 3} is formed due to the chemical reaction between LC and Al{sub 2}O{sub 3} which is the main composition of TGO layer. Additionally, the thermal cycling behavior of DCL coating is influenced by the interdiffusion of Zr and Ce between LZ7C3 and LC coatings. The failure of DCL coating is a result of the sintering of LZ7C3 coating surface, the chemical incompatibility of LC coating and TGO layer and the abnormal oxidation of bond coat. Since no single material that has been studied so far satisfies all the requirements for high temperature applications, DCL coating is an important development direction of TBCs.

  15. Turn-on fluorescent sensor for Zinc and Cadmium ions based on quinolone and its sequential response to phosphate

    International Nuclear Information System (INIS)

    Liu, Xiaoyan; Wang, Peng; Fu, Jiaxin; Yao, Kun; Xue, Kun; Xu, Kuoxi

    2017-01-01

    Sequential fluorescence sensing of Zn 2+ /Cd 2+ ions and phosphate anion by new quinoline based sensors(L1 and L2) have been presented. Sensors exhibit highly selective fluorescence “turn-on” sensing properties to Zn 2+ /Cd 2+ ions in CH 3 OH/H 2 O(1/1, v/v, Tris, 10 mol·L −1 , pH 7.4) solution with a 1:1 binding stoichiometry. The complexes display high selectivity to H 2 PO 4 - and HPO 4 2- anions through fluorescence “turn-off” respond. The results of Zn 2+ /Cd 2+ ions and phosphate anion sequential recognition via fluorescence changes make sensors L1 and L2 have potential utility for Zn 2+ / Cd 2+ ions and phosphate anion detection in aqueous media. - Graphical abstract: Sequential fluorescence sensing of Zn 2+ /Cd 2+ ions and phosphate anion by new quinoline based sensors (L1 and L2) have been presented. Sensors exhibit highly selective and sensitive fluorescence “turn-on” sensing properties to Zn 2+ /Cd 2+ ions in CH 3 OH/H 2 O(1/1, v/v, Tris, 10 mM, pH 7.4) solution with a 1:1 binding stoichiometry. The complexes display high selectivity to H 2 PO 4 - and HPO 4 2- anions through fluorescence “turn-off” respond. Zn 2+ /Cd 2+ ions and phosphate anion sequential recognition via fluorescence changes make sensors L1 and L2 have potential utility for Zn 2+ / Cd 2+ ions and phosphate anion detection in aqueous media.

  16. Phase transition of the orthorhombic fluorite-related compounds Ln{sub 3}IrO{sub 7} (Ln = Pr, Nd, Sm, Eu)

    Energy Technology Data Exchange (ETDEWEB)

    Hinatsu, Yukio, E-mail: hinatsu@sci.hokudai.ac.j [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Doi, Yoshihiro; Nishimine, Hiroaki; Wakeshima, Makoto [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Sato, Mineo [Department of Chemistry and Chemical Engineering, Faculty of Engineering, Niigata University, 8050 Ikarashi 2-nocho, Niigata 950-2181 (Japan)

    2009-12-04

    Rare earth iridium oxides Ln{sub 3}IrO{sub 7} (Ln = Pr, Nd, Sm, and Eu) were prepared and their structures were determined by X-ray diffraction measurements. At room temperature, Pr{sub 3}IrO{sub 7} crystallized in an orthorhombic superstructure of cubic fluorite with space group Cmcm. The differential thermal analysis (DTA) and specific heat measurements for Ln{sub 3}IrO{sub 7} (Ln = Pr, Nd, Sm, and Eu) showed a phase transition at 262, 342, 420, and 485 K, respectively. At low temperatures, Ln{sub 3}IrO{sub 7} crystallized in a monoclinic structure with the space group P2{sub 1}/n. The transition temperatures increased with decreasing the ionic radius of rare earths, which indicates that the transition is stress-induced and occurs with the lattice contraction on cooling. These results for Ln{sub 3}IrO{sub 7} were compared with the phase transitions observed for Ln{sub 3}MoO{sub 7}, Ln{sub 3}RuO{sub 7}, Ln{sub 3}ReO{sub 7}, and Ln{sub 3}OsO{sub 7}.

  17. Thermal properties of KUO3(s) and K2U2O7 - by high temperature Calvet calorimeter

    International Nuclear Information System (INIS)

    Jayanthi, K.; Iyer, V.S.; Venugopal, V.

    1998-01-01

    The thermal properties of KUO 3 (s) and K 2 U 2 O 7 (s) were determined using a high temperature Calvet calorimeter by drop method. The enthalpy increments, (H T o - H 298.15 0 ), in kJ/mol for KUO 3 (s) and K 2 U 2 O 7 (s) can be represented by, H T o - H 298.15 0 KUO 3 (s) kJ/mol ± 0.7 = -39.15 + 0.129T + 0.1005x10 -4 T 2 (369-714K) and H T o -H 298.15 0 K 2 U 2 O 7 (s) kJ/mol ± 0.7 = -52.99 + 0.1361T + 0.146x10 -3 T 2 (391 - 683K). (author)

  18. Lithium-Ion Mobility in Quaternary Boro-Germano-Phosphate Glasses.

    Science.gov (United States)

    Moguš-Milanković, Andrea; Sklepić, Kristina; Mošner, Petr; Koudelka, Ladislav; Kalenda, Petr

    2016-04-28

    Effect of the structural changes, electrical conductivity, and dielectric properties on the addition of a third glass-former, GeO2, to the borophosphate glasses, 40Li2O-10B2O3-(50 - x)P2O5-xGeO2, x = 0-25 mol %, has been studied. Introduction of GeO2 causes the structural modifications in the glass network, which results in a continuous increase in electrical conductivity. Glasses with low GeO2 content, up to 10 mol %, show a rapid increase in dc conductivity as a result of the interlinkage of slightly depolymerized phosphate chains and negatively charged [GeO4](-) units, which enhances the migration of Li(+) ions. The Li(+) ions compensate these delocalized charges connecting both phosphate and germanium units, which results in reduction of both bond effectiveness and binding energy of Li(+) ions and therefore enables their hop to the next charge-compensating site. For higher GeO2 content, the dc conductivity increases slightly, tending to approach a maximum in Li(+) ion mobility caused by the incorporation of GeO2 units into phosphate network combined with conversion of GeO4 to GeO6 units. The strong cross-linkage of germanium and phosphate units creates heteroatomic P-O-Ge bonds responsible for more effectively trapped Li(+) ions. A close correspondence between dielectric and conductivity parameters at high frequencies indicates that the increase in conductivity indeed is controlled by the modification of structure as a function of GeO2 addition.

  19. Properties and solubility of chrome in iron alumina phosphate glasses containing high level nuclear waste

    International Nuclear Information System (INIS)

    Huang, W.; Day, D.E.; Ray, C.S.; Kim, C.W.; Reis, S.T.D.

    2004-01-01

    Chemical durability, glass formation tendency, and other properties of iron alumina phosphate glasses containing 70 wt% of a simulated high level nuclear waste (HLW), doped with different amounts of Cr 2 O 3 , have been investigated. All of the iron alumina phosphate glasses had an outstanding chemical durability as measured by their small dissolution rate (1 . 10 -9 g/(cm 2 . min)) in deionized water at 90 C for 128 d, their low normalized mass release as determined by the product consistency test (PCT) and a barely measurable corrosion rate of 2 . d) after 7 d at 200 C by the vapor hydration test (VHT). The solubility limit for Cr 2 O 3 in the iron phosphate melts was estimated at 4.1 wt%, but all of the as-annealed melts contained a few percent of crystalline Cr 2 O 3 that had no apparent effect on the chemical durability. The chemical durability was unchanged after deliberate crystallization, 48 h at 650 C. These iron phosphate waste forms, with a waste loading of at least 70 wt%, can be readily melted in commercial refractory crucibles at 1250 C for 2 to 4 h, are resistant to crystallization, meet all current US Department of Energy requirements for chemical durability, and have a solubility limit for Cr 2 O 3 which is at least three times larger than that for borosilicate glasses. (orig.)

  20. Molten V2O5/Cs0.9K0.9Na0.2S2O7 and V2O5/K2S2O7 catalysts as electrolytes in an electrocatalytic membrane separation device for SO2 removal

    DEFF Research Database (Denmark)

    Rasmussen, Søren Birk; Eriksen, Kim Michael; Fehrmann, Rasmus

    2002-01-01

    Bench scale fuel cell tests have been carried out on the SO2 oxidation catalyst systems V2O5/M2S2O7 (M = alkali) used as electrolytes in a standard molten carbonate fuel cell (MCFC) fuel cell setup for removal of SO2 from power plant flue gases. Porous LixNi(1-x)O electrodes were used both as anode...... and cathode. The cleaning cell removes SO2 when a potential is applied across the membrane, potentially providing cheap and ecological viable means for regeneration of SO2 from off-gases into high quality H2SO4. Results show that successful removal of up to 80% SO2 at 450 degreesC can be achieved...

  1. 21 CFR 184.1697 - Riboflavin-5′-phosphate (sodium).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Riboflavin-5â²-phosphate (sodium). 184.1697 Section... SAFE Listing of Specific Substances Affirmed as GRAS § 184.1697 Riboflavin-5′-phosphate (sodium). (a) Riboflavin-5′-phosphate (sodium) (C17H20N4O9PNa·2H2O, CAS Reg. No 130-40-5) occurs as the dihydrate in yellow...

  2. PROPERTIES OF Eu3+ LUMINESCENCE IN THE MONOCLINIC Ba2MgSi2O7

    Directory of Open Access Journals (Sweden)

    Shansh an Yao

    2011-09-01

    Full Text Available Red-emitting phosphors Ba2-xMgSi2O7: Eux3+ was prepared by combustion-assisted synthesis method and an efficient red emission under near-ultraviolet (UV was observed. The luminescence and crystallinity were investigated using luminescence spectrometry and X-ray diffractometer. The emission spectrum shows that the most intense peak is located at 614 nm, which corresponds to the 5D0 → 7F2 transitions of Eu3+. The phosphor has two main excitation peaks located at 394 and 465 nm, which match the emission of UV and blue light-emitting diodes, respectively. The effect of Eu3+ concentration on the emission spectrum of Ba2MgSi2O7:Eu3+ phosphor was studied. The results showed that the emission intensity increased with increasing Eu3+ concentration, and then decreased because of concentration quenching. The critical quenching concentration of Eu3+ in Ba2MgSi2O7: Eu3+ phosphor is about 0.05 mol. The mechanism of concentration quenching of Ba2MgSi2O7: Eu3+ luminescence is energy transfer between Eu3+ ions casued by the dipole-dipole interaction.

  3. Crystal structures of CCa2CuO5 and CSr1.9Ca1.1Cu2O7 refined from single crystal data

    International Nuclear Information System (INIS)

    Kopnin, E.M.; Matveev, A.T.; Salamakha, P.S.; Sato, A.; Takayama-Muromachi, E.

    2003-01-01

    Single crystals were grown for new layered oxycarbonates CCa 2 CuO 5 and CSr 1.9 Ca 1.1 Cu 2 O 7 at 6 GPa using a belt-type apparatus. Their crystal structures were determined using single crystal X-ray diffraction data with R1(wR2)=0.0294(0.0659) and 0.0199(0.0457) for CCa 2 CuO 5 and CSr 1.9 Ca 1.1 Cu 2 O 7 , respectively. These phases crystallize in the space group P4/mmm (No. 123), Z=1 with a=3.8157(1) Angst, c=7.1426(3) Angst for CCa 2 CuO 5 and a=3.8753(1) Angst, c=10.6765(5) Angst for CSr 1.9 Ca 1.1 Cu 2 O 7 . In contrast to CSr 2 CuO 5 , no ordering in the orientation of the triangular CO 3 groups was revealed in CCa 2 CuO 5 and CSr 1.9 Ca 1.1 Cu 2 O 7

  4. New compounds bearing [M(S{sub 2}O{sub 7}){sub 3}]{sup 2-} anions (M = Si, Ge, Sn): Syntheses and characterization of A{sub 2}[Si(S{sub 2}O{sub 7}){sub 3}] (A = Na, K, Rb), A{sub 2}[Ge(S{sub 2}O{sub 7}){sub 3}] (A = Li, Na, K, Rb, Cs), A{sub 2}[Sn(S{sub 2}O{sub 7}){sub 3}] (A = Na, K), and the unique germanate Hg{sub 2}[Ge(S{sub 2}O{sub 7}){sub 3}]Cl{sub 2} with cationic {sup 1}{sub ∞}[HgCl{sub 2/2}]{sup +} chains

    Energy Technology Data Exchange (ETDEWEB)

    Logemann, Christian; Witt, Julia; Wickleder, Mathias S. [Universitaet Oldenburg, Institut fuer Reine und Angewandte Chemie (Germany); Gunzelmann, Daniel; Senker, Juergen [Universitaet Bayreuth, Lehrstuhl fuer Anorganische Chemie III (Germany)

    2012-10-15

    The reaction of the group 14 tetrachlorides MCl{sub 4} (M = Si, Ge, Sn) with oleum (65 % SO{sub 3}) at elevated temperatures led to the unique anionic complexes [M(S{sub 2}O{sub 7}){sub 3}]{sup 2-} that show the central M atoms in coordination of three chelating S{sub 2}O{sub 7}{sup 2-} groups. The mean distances M-O within the complexes increase from 175 pm (M = Si) via 186 pm (M = Ge) up to 200 pm (M = Sn). The charge balance for the [M(S{sub 2}O{sub 7}){sub 3}]{sup 2-} anions is achieved by alkaline metal ions A{sup +} (A = Li, Na, K, Rb, Cs) which were implemented in the syntheses in form of their sulfates. The size of the A{sup +} ions, i.e. their coordination requirement causes the crystallographic differences in the crystal structures, while the structure of the complex [M(S{sub 2}O{sub 7}){sub 3}]{sup 2-} anions remains essentially unaffected. Furthermore, we were able to characterize the unique germanate Hg{sub 2}[Ge(S{sub 2}O{sub 7}){sub 3}]Cl{sub 2} which forms when HgCl{sub 2} is added as a source for the counter cation. The Hg{sup 2+} and the Cl{sup -} ions form infinite cationic chains according to {sup 1}{sub ∞}[HgCl{sub 2/2}]{sup +} which take care for the charge compensation. For selected examples of the compounds the thermal behavior has been monitored by means of thermal analyses and X-ray powder diffraction. For A being an alkaline metal the decomposition product is a mixture of the sulfates A{sub 2}SO{sub 4} and the dioxides MO{sub 2}, whereas Hg{sub 2}[Ge(S{sub 2}O{sub 7}){sub 3}]Cl{sub 2} shows a more complicated decomposition. The tris-(disulfato)-silicate Na{sub 2}[Si(S{sub 2}O{sub 7}){sub 3}] has additionally been examined by solid state {sup 29}Si and {sup 23}Na NMR spectroscopic measurements. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Microstructural comparison of Yba2Cu3O7-x thin films laser deposited in O2 and O2/Ar ambient

    DEFF Research Database (Denmark)

    Verbist, K.; Kyhle, Anders; Vasiliev, A.L.

    1996-01-01

    The use of a diluted O-2/Ar atmosphere-for laser deposition of YBa2Cu3O7-x thin films results in a strong decrease of the surface outgrowth density as compared to deposition in pure O-2. The smoother films need a longer oxygenation period and show slightly lower critical current densities; though...... still in excess of 10(6) A cm(-2) at 77 K. Electron microscopy revealed that the outgrowths mainly consist of a large copper-oxide grain connected to Y2O3 grains. Y2O3 nano-scale inclusions are present irrespective of the deposition atmosphere, however at remarkably low densities compared to other...... literature data. We find that the twin plane density is lower and the twin structure more homogeneous in the case of films deposited in a mixture of O-2/Ar. This we ascribe to the absence of surface outgrowths which seem to block regular twin structure formation. Possibly the differences in necessary post...

  6. Formation of YxNd1-xBa2Cu3O7-δ (0≤x≤0.9) superconductors from an undercooled melt via aero-acoustic levitation

    International Nuclear Information System (INIS)

    Gustafson, D.E.; Hofmeister, W.H.; Bayuzick, R.J.; Nagashio, K.; Kuribayashi, K.

    2003-01-01

    This paper presents the results of rapid solidification experiments performed on the copper oxide superconductors Y x Nd 1-x Ba 2 Cu 3 O 7-δ (0≤x≤0.9). Spherical rare earth (RE) 123 specimens were levitated in O 2 using aero-acoustic levitation (AAL), melted with a laser, undercooled, and solidified. The peritectic transformation temperature for the reaction RE 2 BaCuO 5 +liquid→REBa 2 Cu 3 O 7-δ corresponding to the maximum recalescence temperature during solidification was determined. RE123 was formed directly from the melt for Y-Nd binary alloy compositions with Nd concentration greater than 20% (Y concentration less than 80%). A minimum in the peritectic transformation temperature for the Nd/Y123 system corresponding to a composition Y 0.3 Nd 0.7 123 was determined at 66 deg. C below the peritectic of pure Nd123

  7. Effect of alkaline earth oxides on the physical and spectroscopic properties of Dy3+- doped Li2O-B2O3 glasses for white emitting material application

    Science.gov (United States)

    Shamshad, L.; Rooh, G.; Kirdsiri, K.; Srisittipokakun, N.; Damdee, B.; Kim, H. J.; Kaewkhao, J.

    2017-02-01

    Li2O-MO-B2O3:0.5Dy2O3 glasses mixed with four different alkaline earth modifier oxides MgO, CaO, SrO and BaO were synthesized by melt quench technique. Their physical properties like density, molar volume and refractive index were measured at room temperature and the effect of alkaline earth modifier oxides were studied. Also, optical absorption and photoluminescence spectra of these glasses have been acquired at room temperature. The Judd-Ofelt theory was effectively used to characterize these spectra and spectral intensities (ƒcal), Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6) and certain radiative properties have been determined. Radiative life-times (τR), branching ratios (βcal), and emission cross-sections (σp) and optical gain parameters (σp × τR) were calculated from the Judd-Ofelt intensity parameters and the variation in these parameters with the variation of glass matrix are discussed. Yellow/Blue (Y/B) ratio and chromacity color coordinates (x,y) are calculated from the emission spectra which indicates the white light generation from all the investigated samples. The correlated color temperature (CCT) for the studied glasses is found to be 4418 K. The fluorescence decay time (τexp) of the 4F9/2 level of Dy3+ has been measured from the decay profiles and compared with calculated lifetimes (τcal). Among all the studied glass matrices, the glass containing BaO exhibits high value of branching ratio, large emission cross-section and high optical gain parameter for 6F9/2 → 6H13 at 575 nm. The results indicates the suitability of all the studied glasses for laser action and white light generation.

  8. Structural properties of the geometrically frustrated pyrochlore Tb2Ti2O7

    Energy Technology Data Exchange (ETDEWEB)

    Han, Sang-Wook; Gardner, Jason S.; Booth, Corwin H.

    2004-06-14

    Although materials that exhibit nearest-neighbor-only antiferromagnetic interactions and geometrical frustration theoretically should not magnetically order in the absence of disorder, few such systems have been observed experimentally. One such system appears to be the pyrochlore Tb{sub 2}Ti{sub 2}O{sub 7}. However, previous structural studies indicated that Tb{sub 2}Ti{sub 2}O{sub 7} is an imperfect pyrochlore. To clarify the situation, we performed neutron powder diffraction (NPD) and x-ray absorption fine structure (XAFS) measurements on samples that were prepared identically to those that show no magnetic order. The NPD measurements show that the long-range structure of Tb{sub 2}Ti{sub 2}O{sub 7} is well ordered with no structural transitions between 4.5 and 600 K. In particular, mean-squared displacements (u{sup 2}'s) for each site follow a Debye model with no offsets. No evidence for Tb/Ti site interchange was observed within an upper limit of 2%. Likewise, no excess or deficiency in the oxygen stoichiometry was observed, within an upper limit of 2% of the nominal pyrochlore value. Tb L{sub III} and Ti K-edge XAFS measurements from 20-300 K similarly indicate a well-ordered local structure. Other aspects of the structure are considered. We conclude that Tb{sub 2}Ti{sub 2}O{sub 7} has, within experimental error, an ideal, disorder-free pyrochlore lattice, thereby allowing the system to remain in a dynamic, frustrated spin state to the lowest observed temperatures.

  9. Synthesis and crystal structure of 4-fluorobenzylammonium dihydrogen phosphate, [FC6H4CH2NH3]H2PO4

    Directory of Open Access Journals (Sweden)

    Ali Rayes

    2016-12-01

    Full Text Available The asymmetric unit of the title salt, [p-FC6H4CH2NH3]+·H2PO4−, contains one 4-fluorobenzylammonium cation and one dihydrogen phosphate anion. In the crystal, the H2PO4− anions are linked by O—H...O hydrogen bonds to build corrugated layers extending parallel to the ab plane. The FC6H4CH2NH3+ cations lie between these anionic layers to maximize the electrostatic interactions and are linked to the H2PO4− anions through N—H...O hydrogen bonds, forming a three-dimensional supramolecular network. Two hydrogen atoms belonging to the dihydrogen phosphate anion are statistically occupied due to disorder along the OH...HO direction.

  10. Ca2 Al2 SiO7 :Ce3+ phosphors for mechanoluminescence dosimetry.

    Science.gov (United States)

    Tiwari, Geetanjali; Brahme, Nameeta; Sharma, Ravi; Bisen, D P; Sao, Sanjay Kumar; Sahu, Ishwar Prasad

    2016-12-01

    A series of Ce 3+ ion single-doped Ca 2 Al 2 SiO 7 phosphors was synthesized by a combustion-assisted method at an initiating temperature of 600 °C. The samples were annealed at 1100 °C for 3 h and their X-ray diffraction patterns confirmed a tetragonal structure. The phase structure, particle size, surface morphology and elemental analysis were analyzed using X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy techniques. Thermoluminescence (TL) intensity increased with increase in ultraviolet (UV) light exposure time up to 15 min. With further increase in the UV irradiation time the TL intensity decreases. The increase in TL intensity indicates that trap concentration increased with UV exposure time. A broad peak at 121 °C suggested the existence of a trapping level. The peak of mechanoluminescence (ML) intensity versus time curve increased linearly with increasing impact velocity of the moving piston. Mechanoluminescence intensity increased with increase in UV irradiation time up to 15 min. Under UV-irradiation excitation, the TL and ML emission spectra of Ca 2 Al 2 SiO 7 :Ce 3+ phosphor showed the characteristic emission of Ce 3+ peaking at 400 nm (UV-violet) and originating from the Ce 3+ transitions of 5d-4f ( 2 F 5/2 and 2 F 7/2 ). The photoluminescence (PL) emission spectra for Ca 2 Al 2 SiO 7 :Ce 3+ were similar to the ML/TL emission spectra. The mechanism of ML excitation and the suitability of the Ca 2 Al 2 SiO 7 :Ce 3+ phosphor for radiation dosimetry are discussed. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  11. Probing phosphate ion via the europium(III)-modulated fluorescence of gold nanoclusters

    International Nuclear Information System (INIS)

    Ding, Shou-Nian; Li, Chun-Mei; Gao, Bu-Hong; Kargbo, Osman; Zhou, Chan; Chen, Xi; Wan, Neng

    2014-01-01

    Fluorescent gold nanoclusters (Au-NCs) were synthesized by a one-pot method using 11-mercaptoundecanoic acid as a reducing and capping reagent. It is found that the red fluorescence of the Au-NCs is quenched by the introduction of Eu(III) at pH 7.0, but that fluorescence is restored on addition of phosphate. The Au-NCs were investigated by transmission electron microscopy and fluorescence photographs. The effect of pH on fluorescence was studied in the range from pH 6 to 10 and is found to be strong. Based on these findings, we have developed an assay for phosphate. Ions such as citrate, Fe(CN) 6 3− , SO 4 2− , S 2 O 8 2− , Cl − , HS − , Br − , AcO − , NO 2 − , SCN − , ClO 4 − , HCO 3 − , NO 3 − , Cd 2+ , Ba 2+ , Zn 2+ , Mg 2+ , and glutamate do not interfere, but ascorbate and Fe 3+ can quench Au-NCs fluorescence. The fluorescent nanocluster probe responds to phosphate in the range from 0.18 to 250 μM, and the detection limit is 180 nM. The probe also responds to pyrophosphate and ATP. (author)

  12. Fabrication and Thermophysical Properties of La(2-x)Zr(2-y)O7 Nanocrystal by a Sol-Gel Method.

    Science.gov (United States)

    Li, Hui; Che, Ping; Zhao, Ziqiang; Liu, Shixiang; Li, Wenjun

    2016-03-01

    Non-Stoichiometric La2Zr2O7 (La(2-x)Zr(2-y)O7) Nanocrystal was synthesized by a simple sol-gel method. The crystalline structure, oxygen vacancy concentration, thermal expansion coefficient, as well as the fracture toughness of as-prepared materials were charactered by XRD, TG-DSC, PL spectra, dilatometer, and electronic universal testing machine respectively. The crystal structure of La2Zr2O7 is of the cubic type while lattice parameter increases with the deviatation of Zr4+ and La3+ from Stoichiometric La2Zr2O7 increasing. The average linear thermal expansion coefficient of non-stoichiometric La2Zr2O7 is obviously bigger than that of La2Zr2O7 in the temperature range between 150 degrees C and 950 degrees C. The fracture toughness of La(2-x)Zr(2-y)O7 increases with x and y increasing up to x = 0.3 and y = 0.25.

  13. Study of the thorium phosphate-diphosphate (TPD) dissolution: kinetic aspect - thermodynamic aspect: analysis of the neo-formed phases; Etude de la dissolution du phosphate diphosphate de thorium: - aspect cinetique - aspect thermodynamique: analyse des phases neoformees

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, A.Ch

    2000-10-06

    The aim of this work is to study the aqueous corrosion of the thorium phosphate-diphosphate (TPD), of the formula Th{sub 4}(PO{sub 4}){sub 4}P{sub 2}O{sub 7}, in the framework of the actinides immobilization. In order to complete the anterior studies concerning solid solutions where thorium is substituted by a tetravalent ion (uranium (IV) or plutonium (IV)) in the TPD structure, compounds of thorium and neptunium phosphate-diphosphate, of formula Th{sub 4-x}Np{sub x}(PO{sub 4}){sub 4}P{sub 2}O{sub 7}, have been prepared. Furthermore, a new chemical way of synthesis has been investigated in order to sinter solids solution of thorium and uranium phosphate-diphosphate (TUPD) in good conditions. The TPD dissolution study showed two principals steps. The first one corresponds to the control of element concentration by the material dissolution whereas the second corresponds to the formation of secondary precipitates for which thermodynamic equilibrium controls the concentration of the species in solution. Leaching tests have been performed varying several independent parameters in order to determine the TPD dissolution rate. The partial orders related to the protons or to the hydroxide ions have been found between 0.35 and 0.45 whereas the apparent dissolution rate constants are in the range 1.10{sup -5} for 9.10{sup -5} g.m{sup -2}.j{sup -1} for acidic and basic media. The neo-formed phases have been characterized after the dissolution of TPD and TUPD. We found that the TPD leaching in acidic medium leads to the formation of the crystallized thorium phosphate-hydrogen-phosphate (TPHP), of formula Th{sub 2}(PO{sub 4}){sub 2}(HPO{sub 4}), x H{sub 2}O, whereas the TUPD dissolution leads to the TPHP and an other compound, of formula (UO{sub 2}){sub 3}(PO{sub 4}){sub 2}, 5 H{sub 2}O. We calculated its solubility product which is in good agreement with those found in the literature. The phases formed during the leaching of solids containing plutonium; americium or curium (Th

  14. Luminescence properties of Ca2 Ga2 SiO7 :RE phosphors for UV white-light-emitting diodes.

    Science.gov (United States)

    Jiao, Mengmeng; Lv, Wenzhen; Lü, Wei; Zhao, Qi; Shao, Baiqi; You, Hongpeng

    2015-03-16

    A series of Eu(2+) -, Ce(3+) -, and Tb(3+) -doped Ca2 Ga2 SiO7 phosphors is synthesized by using a high-temperature solid-state reaction. The powder X-ray diffraction and structure refinement data indicate that our prepared phosphors are single phased and the phosphor crystalizes in a tetrahedral system with the ${P\\bar 42m}$ (113) space group. The Eu(2+) - and Ce(3+) -doped phosphors both have broad excitation bands, which match well with the UV light-emitting diodes chips. Under irradiation of λ=350 nm, Ca2 Ga2 SiO7 :Eu(2+) and Ca2 Ga2 SiO7 :Ce(3+) , Li(+) have green and blue emissions, respectively. Luminescence of Ca2 Ga2 SiO7 :Tb(3+) , Li(+) phosphor varies with the different Tb(3+) contents. The thermal stability and energy-migration mechanism of Ca2 Ga2 SiO7 :Eu(2+) are also studied. The investigation results indicate that the prepared Ca2 Ga2 SiO7 :Eu(2+) and Ca2 Ga2 SiO7 :Ce(3+) , Li(+) samples show potential as green and blue phosphors, respectively, for UV-excited white-light-emitting diodes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Structural transitions in hybrid improper ferroelectric C a3T i2O7 tuned by site-selective isovalent substitutions: A first-principles study

    Science.gov (United States)

    Li, C. F.; Zheng, S. H.; Wang, H. W.; Gong, J. J.; Li, X.; Zhang, Y.; Yang, K. L.; Lin, L.; Yan, Z. B.; Dong, Shuai; Liu, J.-M.

    2018-05-01

    C a3T i2O7 is an experimentally confirmed hybrid improper ferroelectric material, in which the electric polarization is induced by a combination of the coherent Ti O6 octahedral rotation and tilting. In this work, we investigate the tuning of ferroelectricity of C a3T i2O7 using isovalent substitutions on Ca sites. Due to the size mismatch, larger/smaller alkaline earths prefer A'/A sites, respectively, allowing the possibility for site-selective substitutions. Without extra carriers, such site-selected isovalent substitutions can significantly tune the Ti O6 octahedral rotation and tilting, and thus change the structure and polarization. Using the first-principles calculations, our study reveals that three substituted cases (Sr, Mg, and Sr+Mg) show divergent physical behaviors. In particular, (CaTiO3) 2SrO becomes nonpolar, which can reasonably explain the suppression of polarization upon Sr substitution observed in experiment. In contrast, the polarization in (MgTiO3) 2CaO is almost doubled upon substitutions, while the estimated coercivity for ferroelectric switching does not change. The (MgTiO3) 2SrO remains polar but its structural space group changes, with moderate increased polarization and possible different ferroelectric switching paths. Our study reveals the subtle ferroelectricity in the A3T i2O7 family and suggests one more practical route to tune hybrid improper ferroelectricity, in addition to the strain effect.

  16. Theoretical investigation of the Fermi surfaces of La2-xSrxCuO4 and YBa2Cu3O7

    International Nuclear Information System (INIS)

    Antonov, V.N.; Antonov, Vl.N.; Bar'yakhtar, V.G.; Baglyuk, A.I.; Maksimov, E.G.; Nemoshkalenko, V.V.; Perlov, A.Ya.; Savrasov, S.Yu.; Uspenskii, Yu.A.

    1989-01-01

    A theoretical investigation is made of the shape of the Fermi surface and of the constant-energy surfaces near the Fermi energy of the La 2-x Sr x CuO 4 and YBa 2 Cu 3 O 7 oxides by a self-consistent linear muffin-tin orbital method in the atomic sphere approximation (OMTO-ASA). It is shown that the Fermi surfaces of these compounds are strongly two-dimensional. The Fermi surface of La 2-x Sr x CuO 4 is a corrugated rounded box centered at the point Λ. The Fermi surface of YBa 2 Cu 3 O 7 consists of four sheets: an electron cushion at the point Λ and three nested hole surfaces centered at the point S. The electron cushion and one of the hole surfaces are strongly corrugated along the z direction. The theoretically calculated Fermi surfaces of La 2 CuO 4 and YBa 2 Cu 3 O 7 are compared with the experimental data on electron-positron annihilation

  17. Radiation Tolerance of A2Ti2O7 Materials - A Question of Bonding?

    International Nuclear Information System (INIS)

    Whittle, Karl R.; Lumpkin, Gregory R.; Smith, Katherine L.; Blackford, Mark G.; Harvey, Elizabeth J.; Zaluzec, Nestor J.

    2007-01-01

    The resistance of Ln 2 Ti 2 O 7 (Ln = lanthanide) compounds to radiation damage is an important topic in the understanding and development of new materials by which radioactive nuclear waste can safely be immobilised. A model has been developed, from previously published density functional theory and molecular orbital theory simulations of the band structure for Ln 2 Ti 2 O 7 materials. This model provides a chemical interpretation of radiation stability. (authors)

  18. Study on advanced Ce0.9La0.1O2/Gd2Zr2O7 buffer layers architecture towards all chemical solution processed coated conductors

    DEFF Research Database (Denmark)

    Yue, Zhao; Ma, L.; Wu, W.

    2015-01-01

    2Zr2O7 buffer layer stack and the 200 nm thick YBa2Cu3O7 (YBCO) superconducting layer were sequentially deposited on textured NiW substrates using metal-organic deposition routes. The surface texture of the Gd2Zr2O7 barrier layer deteriorates when the film thickness increases to 80 nm, although...

  19. Effect of pH values on surface modification and solubility of phosphate bioglass-ceramics in the CaO-P 2O 5-Na 2O-SrO-ZnO system

    Science.gov (United States)

    Li, Xudong; Cai, Shu; Zhang, Wenjuang; Xu, Guohua; Zhou, Wei

    2009-08-01

    The bioactive glass-ceramics in the CaO-P 2O 5-Na 2O-SrO-ZnO system were synthesized by the sol-gel technique, and then chemically treated at different pH values to study the solubility and surface modification. Samples sintered at 650 °C for 4 h consisted of the crystalline phase β-Ca 2P 2O 7 and the glass matrix. After soaking in the solution at pH 1.0, the residual glass matrix on the surface appeared entirely dissolved and no new phase could be detected. Whereas at pH 3.0, web-like layer exhibiting peaks corresponding to CaP 2O 6 was formed and covered the entire surface of the sample. When conducted at pH 10.0, only part of the glass matrix was dissolved and a new phase Ca 4P 6O 19 was precipitated, forming the petaline layer. The chemical treatment can easily change the surface morphologies and phase composition of this bioactive glass-ceramics. The higher level of surface roughness resulting from the new-formed layer would improve the interface bonding and benefit for cell adhesion.

  20. Lytic bacteriophages reduce Escherichia coli O157: H7 on fresh cut lettuce introduced through cross-contamination.

    Science.gov (United States)

    Ferguson, Sean; Roberts, Cheryl; Handy, Eric; Sharma, Manan

    2013-01-01

    The role of lytic bacteriophages in preventing cross contamination of produce has not been evaluated. A cocktail of three lytic phages specific for E. coli O157:H7 (EcoShield™) or a control (phosphate buffered saline, PBS) was applied to lettuce by either; (1) immersion of lettuce in 500 ml of EcoShield™ 8.3 log PFU/ml or 9.8 log PFU/ml for up to 2 min before inoculation with E. coli O157:H7; (2) spray-application of EcoShield™ (9.3 log PFU/ml) to lettuce after inoculation with E. coli O157:H7 (4.10 CFU/cm 2 ) following exposure to 50 μg/ml chlorine for 30 sec. After immersion studies, lettuce was spot-inoculated with E. coli O157:H7 (2.38 CFU/cm 2 ). Phage-treated, inoculated lettuce pieces were stored at 4°C for and analyzed for E. coli O157:H7 populations for up to 7 d. Immersion of lettuce in 9.8 log PFU/ml EcoShield™ for 2 min significantly (p PFU/ml) resulted in the deposition of high concentrations (7.8 log log PFU/cm 2 ) of bacteriophages on the surface of fresh cut lettuce, potentially contributing to the efficacy of the lytic phages on lettuce. Spraying phages on to inoculated fresh cut lettuce after being washed in hypochlorite solution was significantly more effective in reducing E. coli O157:H7 populations (2.22 log CFU/cm 2 ) on day 0 compared with control treatments (4.10 log CFU/cm 2 ). Both immersion and spray treatments provided protection from E. coli O157:H7 contamination on lettuce, but spray application of lytic bacteriophages to lettuce was more effective in immediately reducing E. coli O157:H7 populations fresh cut lettuce.

  1. First-principles calculation of the structure and electronic properties of Fe-substituted Bi2Ti2O7

    Science.gov (United States)

    Huang, Jin-Dou; Zhang, Zhenyi; Lin, Feng; Dong, Bin

    2017-12-01

    We performed first-principles calculations to investigate the formation energy, geometry structure, and electronic property of Fe-doped Bi2Ti2O7 systems with different Fe doping content. The calculated formation energies indicate that the substitutional configurations of Fe-doping Bi2Ti2O7 are easy to obtain under O-rich growth condition, but their thermodynamic stability decreases with the increase of Fe content. The calculated spin-resolved density of states and band structures indicate that the introduction of Fe into Bi2Ti2O7 brings high spin polarization. The spin-down impurity levels in Fe x Bi2-x Ti2O7 and spin-up impurity levels in Fe x Bi2Ti2-x O7 systems locate in the bottom of conduction band and narrow the band gap significantly, thus leading to the absorption of visible light. Interestingly, the impurity states in Fe x Bi2-x Ti2O7 are the efficient separation center of photogenerated electron and hole, and less affected by Fe doping content, in comparison, the levels of impurity band in Fe x Bi2Ti2-x O7 systems are largely effected by the Fe doping content, and high Fe doping content is the key factor to improve the separating rate of photogenerated electron and hole.

  2. In Vivo EPR Assessment of pH, pO2, Redox Status, and Concentrations of Phosphate and Glutathione in the Tumor Microenvironment.

    Science.gov (United States)

    Bobko, Andrey A; Eubank, Timothy D; Driesschaert, Benoit; Khramtsov, Valery V

    2018-03-16

    This protocol demonstrates the capability of low-field electron paramagnetic resonance (EPR)-based techniques in combination with functional paramagnetic probes to provide quantitative information on the chemical tumor microenvironment (TME), including pO2, pH, redox status, concentrations of interstitial inorganic phosphate (Pi), and intracellular glutathione (GSH). In particular, an application of a recently developed soluble multifunctional trityl probe provides unsurpassed opportunity for in vivo concurrent measurements of pH, pO2 and Pi in Extracellular space (HOPE probe). The measurements of three parameters using a single probe allow for their correlation analyses independent of probe distribution and time of the measurements.

  3. The effect of rare earth dopants on the structure, surface texture and photocatalytic properties of TiO2-SiO2 prepared by sol-gel method

    International Nuclear Information System (INIS)

    Mohamed, R.M.; Mkhalid, I.A.

    2010-01-01

    The sol-gel method was successfully used to prepare a series of TiO 2 -SiO 2 and rare earth (RE) (La 3+ , Nd 3+ , Sm 3+ , Gd 3+ )-doped TiO 2 -SiO 2 nanoparticles at a doping level of 3 atomic percent. The structural features of parent TiO 2 -SiO 2 and RE-TiO 2 -SiO 2 fired at 550 o C have been investigated by XRD, UV-diffuse reflection, SEM and nitrogen adsorption measurements at -196 o C. XRD data verified the formation of typical characteristic anatase form in all the prepared RE-doped TiO 2 -SiO 2 samples. In comparison with the pure TiO 2 -SiO 2 samples (ca. 35 nm in diameter), the RE-TiO 2 -SiO 2 samples have relatively small particle size indicating that the doping with RE metal ions can improve the particle morphology, and retard the grain growth of TiO 2 -SiO 2 during heat treatment. The results indicated that Gd 3+ doped TiO 2 -SiO 2 has the lowest bandgap and particle size compared with pure TiO 2 -SiO 2 and other nanoparticles of RE-doped TiO 2 -SiO 2 . The highest surface area (S BET ) and pore volume (V p ) values were recorded for Gd-TiO 2 -SiO 2 as well. The effect of doping on the photoactivity was evaluated by the photocatalytic degradation of EDTA as a probe reaction. Among all the pure and RE-doped TiO 2 -SiO 2 , Gd 3+ -TiO 2 -SiO 2 performed the highest catalytic activity towards the tested reaction. That might be due to its special characteristics of particle size, surface texture and bandgap properties. Details of the synthesis procedure and results of the characterization studies of the produced RE-TiO 2 -SiO 2 are presented in this paper.

  4. Raman spectrum, quantum mechanical calculations and vibrational assignments of (95% alpha-TeO2/5% Sm2O3) glass.

    Science.gov (United States)

    Shaltout, I; Mohamed, Tarek A

    2007-06-01

    Chozen system of tellurite glasses doped with rare earth oxides (95% alpha-TeO(2)+5% Sm2O3) was prepared by melt quenching. Consequently, the Raman spectrum (150-1250 cm(-1)) of the modified tellurite have been recorded. As a continuation to our normal coordinate analysis, force constants and quantum mechanical (QM) calculations for tbp TeO4(4-) (triagonal bipyramid, C(2v)) and TeO(3+1); Te2O7(6-) (bridged tetrahedral), we have carried out ab initio frequency calculations for tpy TeO3(2-) (triagonal pyramidal, C(3v) and C(s)) and tp TeO3(2-) (triagonal planar, D(3h)) ions. The quantum mechanical calculations at the levels of RHF, B3LYP and MP2 allow confident vibrational assignments and structural identification in the binary oxide glass (95% alpha-TeO2 +5% Sm2O3). The dominant three-dimensional network structures in the modified glass are triagonal pyramidal TeO3 with minor features of short range distorted tbp TeO4 and bridged tetrahedral unit of TeO(3+1), leading to a structure of infinite chain. Therefore, alpha-TeO2/Sm2O3 (95/5%) glass experience structural changes from TeO4 (tbp); Te2O7 (TeO(3+1))-->TeO3 (tpy).

  5. Multifunctional Sm2-xDyxZr2O7 pyrochlore system: potential ionic conductors and photocatalysts

    International Nuclear Information System (INIS)

    Grover, V.; Sayed, Farheen N.; Bhattacharyya, K.; Jain, D.; Pillai, C.G.S.; Tyagi, A.K.; Arya, A.

    2010-01-01

    Full text: Pyrochlores have garnered considerable interest over the years because of a range of potentially useful properties such as fast-ion (mainly anion) conductivity, electrical conductivity, catalysis, luminescence etc. In present work a series of Sm 2-x Dy x Zr 2 O 7 compounds (0.0 ≤ x ≤ 2.0) were synthesized by gel combustion and characterized by Powder XRD and Raman spectroscopic studies. XRD studies revealed the system to be single-phasic throughout with the retention of pyrochlore phase till 40 mol% of Dy 3+ beyond which, an order-disorder phase transition occurred resulting in a defect fluorite structure. Surprisingly, Raman studies showed the retention of pyrochlore type ordering till the other end member, i.e. Dy 2 Zr 2 O 7 . This is the first study, which reports the retention of a weak pyrochlore type superstructure in Dy 2 Zr 2 O 7 system. Ionic conductivity measurements were performed on these samples, which showed that the activation Energy (E a ) increases with increase in Dy 3+ mol% owing to the decreased mobility with increasing degree of disorder. The representative nquist Plots are given for Sm 2 Zr 2 O 7 . These materials have a definite band gap absorbing mainly in the UV region which makes them good candidates for photocatalysed dye degradation studies. Potential of some of these compositions as photocatalysts was also explored and they were found to efficiently catalyse the degradation of Xylenol Orange with t 1/2 decreasing from pure Sm 2 Zr 2 O 7 to pure Dy 2 Zr 2 O 7

  6. Isotope effect on superconductivity and Raman phonons of Pyrochlore Cd2Re2O7

    Science.gov (United States)

    Razavi, F. S.; Hajialamdari, M.; Reedyk, M.; Kremer, R. K.

    2018-06-01

    Cd2Re2O7 is the only α-Pyrochlore exhibiting superconductivity with a transition temperature (Tc) of ∼ 1 K. In this study, we present the effect of oxygen isotope (18O) as well as combined 18O and cadmium isotope (116Cd) substitution on the superconductivity and Raman scattering spectrum of Cd2Re2O7. The change of Tc and the energy gap Δ(T) are reported using various techniques including point contact spectroscopy. The shift in Raman phonon frequencies upon isotope substitution will be compared with measurement of the isotope effect on the superconducting transition temperature.

  7. Solubility and superconductivity in RE(Ba2-xREx)Cu3O7+δ (RE = Nd, Sm, Eu, Gd, Dy)

    International Nuclear Information System (INIS)

    Zhang, K.; Dabrowski, B.; Segre, C.U.; Hinks, D.G.; Schuller, I.K.; Jorgensen, J.D.; Slaski, M.

    1987-10-01

    Solid solutions of RE(Ba 2-x RE x )Cu 3 O 7- δ (RE=Nd,Sm,Eu,Gd,Dy) for x=0 to x=0.5 have been investigated. X-ray and resistivity measurements show that there exists a solid solution region, through which, the structure changes from orthorhombic to tetragonal and the superconducting properties are depressed. The solubility limits depend strongly on the size of the rare-earth ion, with the smallest (Dy) showing no appreciable solubility. The superconducting transition temperature versus x for all of the rare-earth ion substitutions falls on a universal curve, indicating that the Ba sites are extremely ionic and magnetically isolated. 20 refs., 4 figs

  8. Formation of qualified BaHfO3 doped Y0.5Gd0.5Ba2Cu3O7-δ film on CeO2 buffered IBAD-MgO tape by self-seeding pulsed laser deposition

    Science.gov (United States)

    Liu, Linfei; Wang, Wei; Yao, Yanjie; Wu, Xiang; Lu, Saidan; Li, Yijie

    2018-05-01

    Improvement in the in-filed transport properties of REBa2Cu3O7-δ (RE = rare earth elements, REBCO) coated conductor is needed to meet the performance requirements for various practical applications, which can be accomplished by introducing artificial pinning centers (APCs), such as second phase dopant. However, with increasing dopant level the critical current density Jc at 77 K in zero applied magnetic field decreases. In this paper, in order to improve Jc we propose a seed layer technique. 5 mol% BaHfO3 (BHO) doped Y0.5Gd0.5Ba2Cu3O7-δ (YGBCO) epilayer with an inserted seed layer was grown on CeO2 buffered ion beam assisted deposition MgO (IBAD-MgO) tape by pulsed laser deposition. The effect of the conditions employed to prepare the seed layer, including tape moving speed and chemical composition, on the quality of 5 mol% BHO doped YGBCO epilayer was systematically investigated by X-ray diffraction (XRD) measurements and scanning electron microscopy (SEM) observations. It was found that all the samples with seed layer have higher Jc (77 K, self-field) than the 5 mol% BHO doped YGBCO film without seed layer. The seed layer could inhibit deterioration of the Jc at 77 K and self-filed. Especially, the self-seed layer (5 mol% BHO doped YGBCO seed layer) was more effective in improving the crystal quality, surface morphology and superconducting performance. At 4.2 K, the 5 mol% BHO doped YGBCO film with 4 nm thick self-seed layer had a very high flux pinning force density Fp of 860 GN/m3 for B//c under a 9 T field, and more importantly, the peak of the Fp curve was not observed.

  9. Unique crystallization behavior of sodium manganese pyrophosphate Na2MnP2O7 glass and its electrochemical properties

    Directory of Open Access Journals (Sweden)

    Morito Tanabe

    2017-06-01

    Full Text Available Crystallization behavior of Na2MnP2O7 precursor glass was examined. Layered type Na2MnP2O7 was formed at 461 °C for 3 h in N2 filled electric furnace. Irreversible phase change was confirmed from layered Na2MnP2O7 to β-Na2MnP2O7 over 600 °C. At 650 °C crystallized phase was completely changed to β-phase. By means of charge and discharge testing it is found that layered Na2MnP2O7 is also active as cathode in sodium ion batteries. We found glass-ceramics technology is one of the suitable process for the synthesis of layered Na2MnP2O7 cathode without any complicate process.

  10. Doping-induced quantum crossover in Er2Ti2 -xSnxO7

    Science.gov (United States)

    Shirai, M.; Freitas, R. S.; Lago, J.; Bramwell, S. T.; Ritter, C.; Živković, I.

    2017-11-01

    We present the results of the investigation of magnetic properties of the Er2Ti2 -xSnxO7 series. For small doping values, the ordering temperature decreases linearly with x , while the moment configuration remains the same as in the x =0 parent compound. Around x =1.7 doping level, we observe a change in the behavior, where the ordering temperature starts to increase and new magnetic Bragg peaks appear. For the first time, we present evidence of a long-range order (LRO) in Er2Sn2O7 (x =2.0 ) below TN=130 mK. It is revealed that the moment configuration corresponds to a Palmer-Chalker type with a value of the magnetic moment significantly renormalized compared to x =0 . We discuss our results in the framework of a possible quantum phase transition occurring close to x =1.7 .

  11. Uranium-phosphate relationship in phosphated chalks of the Mons and Picardie Bassins

    Energy Technology Data Exchange (ETDEWEB)

    Quinif, Y; Charlet, J M; Dupuis, C; Robaszynski, F [Faculte Polytechnique de Mons (Belgium)

    1981-11-30

    The lithological and geochemical conditions relative to the ''Senonian'' phosphatic chalks are relatively simple in the Basins of Mons (Belgium) and of Picardy (France). Their characteristics permit us to study chiefly the uranium-phosphate relation. It appears a very good linear correlation between the phosphate and the uranium. The coefficient U/P/sub 2/O/sub 5/ remains a constant from the bottom to the top of the same section, but changes in space for synchronic formations (lateral variation of geochemical facies) and in time for two separated basins.

  12. Kinetic study of the thorium phosphate - diphosphate dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Dacheux, N.; Thomas, A.C.; Brandel, V.; Genet, M. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Aupiais, J. [CEA/DAM-Ile de France, Dept. Analyse Surveillance Environnement, DASE, Service Radioanalyses Chimie Environnement, 91 - Bruyeres-Le-Chatel (France)

    2000-07-01

    The thorium phosphate-diphosphate Th{sub 4}(PO{sub 4}){sub 4}P{sub 2}O{sub 7} (TPD) structure allows the replacement of large amounts of thorium by tetravalent actinides leading to the formation of solid solutions. This compound was obtained in powdered or sintered form after pressing at room temperature at 300-800 MPa then heating at 1250 deg. C for 10-30 hours. The resistance of this material to aqueous corrosion was determined by varying several parameters such as surface, leaching flow, acidity or temperature. It was thus possible to independently determine the influence of each parameter on the leaching rate provided that the saturation of the solution was not obtained. In acidic media, the partial order related to [H{sub 3}O{sup +}] was found to be in the 0.31-0.35 range while, in basic media, the partial order related to [OH{sup -}] was almost the same (0.45). The activation energy (42 kJ/mol) was determined between 4 deg. C and 120 deg. C. Moreover, the addition of phosphate in the leachate slightly increased the TPD dissolution rate. When the saturation of the solution is reached, a gelatinous precipitate controls the thorium and phosphate concentrations. The complete characterization of this solid led to the proposed general formula Th{sub 2}(PO{sub 4}){sub 2}(HPO{sub 4}). n H{sub 2}O which conventional solubility product (at I = 0 M) is very low: K{sup *}{sub S,0} 10{sup -66.6{+-}}{sup 1.2} even in very acidic media. (authors)

  13. Damage evolution of ion irradiated defected-fluorite La 2 Zr 2 O 7 epitaxial thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kaspar, Tiffany C.; Gigax, Jonathan G.; Shao, Lin; Bowden, Mark E.; Varga, Tamas; Shutthanandan, Vaithiyalingam; Spurgeon, Steven R.; Yan, Pengfei; Wang, Chongmin; Ramuhalli, Pradeep; Henager, Charles H.

    2017-05-01

    Pyrochlore-structure oxides, A2B2O7, may exhibit remarkable radiation tolerance due to the ease with which they can accommodate disorder by transitioning to a defected fluorite structure. The mechanism of defect formation was explored by evaluating the radiation damage behavior of high quality epitaxial La2Zr2O7 thin films with the defected fluorite structure, irradiated with 1 MeV Zr+ at doses up to 10 displacements per atom (dpa). The level of film damage was evaluated as a function of dose by Rutherford backscattering spectrometry in the channeling geometry (RBS/c) and scanning transmission electron microscopy (STEM). At lower doses, the surface of the La2Zr2O7 film amorphized, and the amorphous fraction as a function of dose fit well to a stimulated amorphization model. As the dose increased, the surface amorphization slowed, and amorphization appeared at the interface. Even at a dose of 10 dpa, the core of the film remained crystalline, despite the prediction of amorphization from the model. To inform future ab initio simulations of La2Zr2O7, the bandgap of a thick La2Zr2O7 film was measured to be indirect at 4.96 eV, with a direct transition at 5.60 eV.

  14. Simulation of YBa{sub 2}Cu{sub 3}O{sub 7}/MgO surface growth

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadizadeh, M.R. [Superconductivity Research Laboratory (SRL), Department of Physics, University of Tehran, North Karegar Ave., P.O. Box 14395-547, Tehran (Iran); Computational Physical Sciences Research Laboratory, Department of Nano-Science, Institute for Studies in Theoretical Physics and Mathematics (IPM), P.O. Box 19395-5531, Tehran (Iran); Safari, N.; Kia, M.; Savaloni, H. [Superconductivity Research Laboratory (SRL), Department of Physics, University of Tehran, North Karegar Ave., P.O. Box 14395-547, Tehran (Iran)

    2006-09-15

    For surface growth simulation of YBa{sub 2}Cu{sub 3}O{sub 7} on MgO substrate, binding energies between each two different Y, Ba, Cu, O, and Mg atoms were calculated by ab initio pseudopotential density functional theory approach. Then, simulation of YBa{sub 2}Cu{sub 3}O{sub 7} growth was performed by a simple two dimensional model based on the ballistic aggregation of hard discs. By increasing the substrate temperature, the atomic layers distribution is more condensed and the nanometric surface roughness decreases. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Effect of phosphate supplementation on oxygen delivery at high altitude

    Science.gov (United States)

    Jain, S. C.; Singh, M. V.; Rawal, S. B.; Sharma, V. M.; Divekar, H. M.; Tyagi, A. K.; Panwar, M. R.; Swamy, Y. V.

    1987-09-01

    In the present communication, effect of low doses of phosphate supplementation on short-term high altitude adaptation has been examined. Studies were carried out in 36 healthy, male, sea-level residents divided in a double blind fashion into drug and placebo treated groups. 3.2 mmol of phosphate were given orally to each subject of the drug treated group once a day for 4 days on arrival at an altitude of 3,500 m. Sequential studies were done in the subjects in both groups on the 3rd, 7th, 14th and 21st day of their altitude stay. Haemoglobin, haematocrit, erythrocyte and reticulocyte counts increased to the similar extent in both groups. Blood pH, pO2 and adenosine tri-phosphate (ATP) did not differ between the two groups. On 3rd day of the altitude stay, inorganic phosphate and 2,3-diphosphoglycerate (2,3 DPG) levels in the drug treated group increased significantly as compared to the placebo group. No significant difference in inorganic phosphate and 2,3 DPG was observed later on in the two groups. Psychological and clinical tests also indicated that the drug treated subjects felt better as compared to the placebo treated subjects. The present study suggests that low doses of phosphate increases circulating 2,3-DPG concentration which in turn brings about beneficial effect towards short term high altitude adaptation.

  16. Transmission electron microscopic study of pyrochlore to defect-fluorite transition in rare-earth pyrohafnates

    Energy Technology Data Exchange (ETDEWEB)

    Karthik, Chinnathambi, E-mail: Karthikchinnathambi@boisestate.edu [Department of Materials Science and Engineering, Boise State University, 1910 University drive, Boise, ID 83725 (United States); Center for Advanced Energy Studies, 995 University Blvd, Idaho Falls, ID 83415 (United States); Anderson, Thomas J. [Department of Materials Science and Engineering, Boise State University, 1910 University drive, Boise, ID 83725 (United States); Gout, Delphine [Oak Ridge National Lab, Neutron Scattering Science Division, Oak Ridge, TN (United States); Ubic, Rick [Department of Materials Science and Engineering, Boise State University, 1910 University drive, Boise, ID 83725 (United States); Center for Advanced Energy Studies, 995 University Blvd, Idaho Falls, ID 83415 (United States)

    2012-10-15

    A structural transition in rare earth pyrohafnates, Ln{sub 2}Hf{sub 2}O{sub 7} (Ln=Y, La, Pr, Nd, Tb, Dy, Yb and Lu), has been identified. Neutron diffraction showed that the structure transforms from well-ordered pyrochloric to fully fluoritic through the lanthanide series from La to Lu with a corresponding increase in the position parameter x of the 48f (Fd3{sup Macron }m) oxygen site from 0.330 to 0.375. As evidenced by the selected area electron diffraction, La{sub 2}Hf{sub 2}O{sub 7}, Pr{sub 2}Hf{sub 2}O{sub 7} and Nd{sub 2}Hf{sub 2}O{sub 7} exhibited a well-ordered pyrocholoric structure with the presence of intense superlattice spots, which became weak and diffuse (in Dy{sub 2}Hf{sub 2}O{sub 7} and Tb{sub 2}Hf{sub 2}O{sub 7}) before disappearing completely as the series progressed towards the Lu end. High resolution electron microscopic studies showed the breakdown of the pyrochlore ordering in the form of antiphase domains resulting in diffused smoke-like superlattice spots in the case of Dy{sub 2}Hf{sub 2}O{sub 7} and Tb{sub 2}Hf{sub 2}O{sub 7}. - Graphical abstract: Transmission electron microscopic studies showed the ordered pyrochlore to defect fluorite transition in rare-earth pyrohafnates to occur via the formation of anti-phase domains to start with. Highlights: Black-Right-Pointing-Pointer Pyrochlore to fluorite structural transition in rare earth pyrohafnates. Black-Right-Pointing-Pointer La{sub 2}Hf{sub 2}O{sub 7}, Pr{sub 2}Hf{sub 2}O{sub 7} and Nd{sub 2}Hf{sub 2}O{sub 7} showed well ordered pyrochlore structure. Black-Right-Pointing-Pointer Short range ordering in Dy{sub 2}Hf{sub 2}O{sub 7} and Tb{sub 2}Hf{sub 2}O{sub 7}. Black-Right-Pointing-Pointer Break down of pyrochlore ordering due to antiphase boundaries. Black-Right-Pointing-Pointer Rest of the series showed fluoritic structure.

  17. Solidification of metallic aluminum on magnesium phosphate cements

    International Nuclear Information System (INIS)

    Lahalle, Hugo

    2016-01-01

    This work deals with the stabilization/solidification of radioactive waste using cement. More particularly, it aims at assessing the chemical compatibility between metallic aluminum and mortars based on magnesium phosphate cement. The physical and chemical processes leading to setting and hardening of the cement are first investigated. X-ray diffraction (XRD), thermogravimetry (TGA) and nuclear magnetic resonance spectroscopy ("3"1P and "1"1B MAS-NMR) are first used to characterize the solid phases formed during hydration, while inductively coupled plasma atomic emission spectroscopy analysis (ICP-AES), electrical conductometry and pH measurements provide information on the pore solution composition. Then, the corrosion of metallic aluminum in magnesium phosphate mortars is studied by monitoring the equilibrium potential and by electrochemical impedance spectroscopy (EIS). Magnesium phosphate cement is prepared from a mix of magnesium oxide (MgO) and potassium dihydrogen orthophosphate (KH_2PO_4). In the presence of water, hydration occurs according to a dissolution - precipitation process. The main hydrate is K-struvite (MgKPO_4.6H_2O). Its precipitation is preceded by that of two transient phases: phosphorrosslerite (MgHPO_4.7H_2O) and Mg_2KH(PO_4)_2.15H_2O. Boric acid retards cement hydration by delaying the formation of cement hydrates. Two processes may be involved in this retardation: the initial precipitation of amorphous or poorly crystallized minerals containing boron and phosphorus atoms, and/or the stabilization of cations (Mg"2"+, K"+) in solution. As compared with a Portland cement-based matrix, corrosion of aluminum is strongly limited in magnesium phosphate mortar. The pore solution pH is close to neutrality and falls within the passivation domain of aluminum. Corrosion depends on several parameters: it is promoted by a water-to-cement ratio (w/c) significantly higher than the chemical water demand of cement (w/c = 0.51), and by the addition of boric

  18. Electronic structure of the CuO3 chains in RBa2Cu3O6+x (R=Y or a rare earth)

    International Nuclear Information System (INIS)

    Aligia, A.A.; Gagliano, E.R.; Vairus, P.

    1995-01-01

    We consider the appropriate generalization of the three-band Hubbard model to describe the CuO 3 chains of RBa 2 Cu 3 O 6+x (R=Y or a rare earth). The model is mapped numerically into a t-J model with t∼0.85 eV and J∼0.2 eV. Making the reasonable assumption that ∼5% of the O atoms between two Cu atoms are lacking, the model allows an explanation of the optical conductivity σ(ω) of the chains, the small change of the occupation of the chains when Y is substituted by Pr, and the charge corrugations observed by scanning-tunneling microscopy

  19. Synthesis and characterisation of the n = 2 Ruddlesden–Popper phases Ln2Sr(Ba)Fe2O7 (Ln = La, Nd, Eu)

    International Nuclear Information System (INIS)

    Gurusinghe, Nicola N.M.; Figuera, Juand de la; Marco, José F.; Thomas, Michael F.; Berry, Frank J.; Greaves, Colin

    2013-01-01

    Graphical abstract: - Highlights: • Some Ruddlesden–Popper phases have been characterised. • Substitution on the A site influences cationic order. • The magnetic moment redirects with temperature - Abstract: A series of n = 2 Ruddlesden–Popper phases A 2 B 2 O 7 of composition Ln 2 Sr(Ba)Fe 2 O 7 (Ln = La, Nd, Eu) have been prepared. La 2 SrFe 2 O 7 and La 2 BaFe 2 O 7 crystallise in the tetragonal space group I4/mmm. The structures of Eu 2 SrFe 2 O 7 and Nd 2 SrFe 2 O 7 are best described in space group P4 2 /mnm. Substitution on the A site with smaller lanthanide- and larger alkaline metal- ions leads to enhanced cationic order in these phases and reflects increasing differences in cationic radii. All the compounds are antiferromagnetically ordered between 298 and 2 K. In La 2 SrFe 2 O 7 the magnetic moment lies along [1 1 0] at all temperatures between 298 and 2 K whereas in La 2 BaFe 2 O 7 the magnetic moment at 298 K lies along the crystallographic x-axis but redirects from the [1 0 0] to the [1 1 0] direction between 210 and 190 K and is retained in this direction until 2 K. In Nd 2 SrFe 2 O 7 the magnetic moment at 298 K lies along [1 1 0] but rotates from [1 1 0] to [0 0 1] between 17 and 9 K. A series of 57 Fe Mössbauer spectra recorded from La 2 SrFe 2 O 7 between 290 and 600 K indicate a magnetic ordering temperature of T N ≥ 535 K

  20. Structural and thermodynamic study of dicesium molybdate Cs2Mo2O7: Implications for fast neutron reactors

    Science.gov (United States)

    Smith, A. L.; Kauric, G.; van Eijck, L.; Goubitz, K.; Wallez, G.; Griveau, J.-C.; Colineau, E.; Clavier, N.; Konings, R. J. M.

    2017-09-01

    The structure of α-Cs2Mo2O7 (monoclinic in space group P21 / c), which can form during irradiation in fast breeder reactors in the space between nuclear fuel and cladding, has been refined in this work at room temperature from neutron diffraction data. Furthermore, the compounds' thermal expansion and polymorphism have been investigated using high temperature X-ray diffraction combined with high temperature Raman spectroscopy. A phase transition has been observed at Ttr(α → β)=(621.9±0.8) K using Differential Scanning Calorimetry, and the structure of the β-Cs2Mo2O7 phase, orthorhombic in space group Pbcm, has been solved ab initio from the high temperature X-ray diffraction data. Furthermore, the low temperature heat capacity of α-Cs2Mo2O7 has been measured in the temperature range T=(1.9-313.2) K using a Quantum Design PPMS (Physical Property Measurement System) calorimeter. The heat capacity and entropy values at T=298.15 K have been derived as Cp,mo (Cs2Mo2O7 , cr , 298.15 K) = (211.9 ± 2.1) J K-1mol-1 and Smo (Cs2Mo2O7 , cr , 298.15 K) = (317.4 ± 4.3) J K-1mol-1 . When combined with the enthalpy of formation reported in the literature, these data yield standard entropy and Gibbs energy of formation as Δf Smo (Cs2Mo2O7 , cr , 298.15 K) = - (628.2 ± 4.4) J K-1mol-1 and Δf Gmo (Cs2Mo2O7 , cr , 298.15 K) = - (2115.1 ± 2.5) kJmol-1 . Finally, the cesium partial pressure expected in the gap between fuel and cladding following the disproportionation reaction 2Cs2MoO4=Cs2Mo2O7+2Cs(g)+ 1/2 O2(g) has been calculated from the newly determined thermodynamic functions.

  1. New α-Zn2V2O7/carbon nanotube nanocomposite for supercapacitors

    International Nuclear Information System (INIS)

    Venugopal, Nulu; Kim, Woo-Sik

    2015-01-01

    This study synthesized α-Zn 2 V 2 O 7 nanopowders using a hydrothermal approach followed by annealing treatment. The resulting powders were then mixed with multi-walled carbon nanotubes and electrochemically characterized as new nanocomposite electrodes for supercapacitors. The structure and surface morphology of the powders were characterized by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Plus, the capacitive behavior of the composite electrodes was evaluated by cyclic voltammetry and galvanostatic charge-discharge cycles in different molar aqueous KCl solutions. The α-Zn 2 V 2 O 7 /multi-walled carbon nanotube composite electrodes were prepared using three different ratios and screened for their use in supercapacitors. As a result, the α-Zn 2 V 2 O 7 / multi-walled carbon nanotube composite electrode with a 1 : 2 ratio was identified as the best electrode with a specific capacitance value of 44.8 F g -1 in 0.5M KCl. Notwithstanding, all the tested composite electrodes demonstrated an excellent cycle stability and showed a less than 4% change in their specific capacitance values when compared to the initial values.

  2. Low temperature synthesis and photoluminescence study of Y2Ti2O7:Eu nanoparticles

    International Nuclear Information System (INIS)

    Selvi, E.; Prasad, A.I.; Nigam, Sandeep; Sudarsan, V.; Vatsa, R.K.

    2014-01-01

    Very small nanoparticles both undoped and doped Y 2 Ti 2 O 7 were prepared at a low temperature (700℃). The obtained undoped and doped Y 2 Ti 2 O 7 samples exhibit good crystallinity, smaller average crystallite size. Based on the detailed luminescence studies, it is confirmed that the lanthanide doped nano-materials have improved luminescence properties compared to the corresponding bulk samples. (author)

  3. Studies on Ba(2)YNbO(6) Buffer Layers for Subsequent YBa(2)Cu(3)O(7-x) Film Growth

    National Research Council Canada - National Science Library

    Sathiraju, Srinivas; Barnes, Paul N; Varanasi, Chakrapani; Wheeler, Robert

    2004-01-01

    In this paper, we are reporting a dielectric oxide buffer Ba(2)YNbO(6) (BYNO) and its performance on various substrates for a potential buffer layer for the growth of YBa(2)Cu(3)O(7-x) (YBCO) coated conductors. Ba(2)YNbO(6...

  4. Homogeneity of peraluminous SiO2-B2O3-Al2O3-Na2O-CaO-Nd2O3 glasses: Effect of neodymium content

    International Nuclear Information System (INIS)

    Gasnier, E.; Bardez-Giboire, I.; Massoni, N.; Montouillout, V.; Pellerin, N.; Allix, M.; Ory, S.; Cabie, M.; Poissonnet, S.; Massiot, D.

    2014-01-01

    Considering the interest of developing new glass matrices able to immobilize higher concentration of high level nuclear wastes than currently used nuclear borosilicate compositions, glasses containing high rare earth contents are of particular interest. This study focuses on a peraluminous alumino borosilicate system SiO 2 -B 2 O 3 -Al 2 O 3 -Na 2 O-CaO-Nd 2 O 3 defined by a per-alkaline/peraluminous ratio RP = ([Na 2 O] + [CaO])/ ([Na 2 O] + [CaO] + [Al 2 O 3 ]) ≤ 0.5. Samples with various contents of Nd 2 O 3 from 0 to 10 mol% were studied using DSC, XRD, SEM, TEM, STEM and EMPA methods. The glasses present a high thermal stability even after a slow cooling treatment from the melt. Only a slight mullite crystallization is detected for low Nd 2 O 3 content (≤2.3 mol%) and crystallization of a neodymium borosilicate crystalline phase combined to a phase separation occurred at high Nd 2 O 3 content (≥8 mol%). The solubility of neodymium in the presence of aluminum is demonstrated, with higher neodymium incorporation amounts than in per-alkaline glasses. (authors)

  5. Determination of metals and rare earths in leach solution of phosphogypsum by instrumental neutron activation analysis (INAA)

    International Nuclear Information System (INIS)

    Costa, Gabriela J.L.; Saueia, Catia H.R.; Mazzilli, Barbara P.

    2011-01-01

    The phosphogypsum is a sub-product of the fertilizer industries and is composed of the gypsum matrix (CaSO 4 .2H 2 O) which naturally contains high tenors of impurities such as 2P O 5 and metals coming from the original phosphat rock. The Brazilian phosphogypsum and the various uses has been researched through his elementary and radiochemistry characterization. This work determine the metals (As, Ba, Co and Se) and rare earths (La, Ce, Sm, Eu, Tb and Lu) presents in samples of phosphogypsum leach solutions

  6. Lead, Chromium and Cadmium Removal from Contaminated Water Using Phosphate Sorbents

    Directory of Open Access Journals (Sweden)

    Fariborz Riahi

    2010-06-01

    Full Text Available Sorption of 3 poisonous metal ions (Pb2+, Cd2+, Cr3+ in aqueous solutions by two phosphate sorbents under dynamic and static conditions was studied. Phosphate sorbents (MgNH4PO4. H2O, Mg3(PO42. 6H2O were synthesized by known procedures. The resulting crystalline samples were analyzed for the contents of Mg2+, Pb2+, P, N using spectrophotometric and elemental analysis methods. Likewise, the amounts of Pb2+, Cd2+, Cr3+ in solutions were determined before and after the sorption process using the atomic absorption method. The relative standard deviations for Pb2+, Cd2+, Cr3+ were 4.7%, 2.17%, and 1.61% and the detection limits were 5 g/L, 0.05 mg/L, and 0.1 mg/L, respectively. The sorbents showed a high performance in the purification of contaminated solutions under static conditions. The sorption capacity levels of Mg3 (PO42. 6H2O and MgNH4 PO4. H2O were 9.8m.mol/gr and 8.9m.mol/gr for Pb2+; 10.5m.mol/gr and 9m.mol/gr for Cd2+; and 6.6m.mol/gr and 5.3m.mol/gr for Cr3+, respectively. Pb2+ , Cd2+, Cr3+. sorption by inorganic phosphate sorbents from solutions is associated with complicated chemical transformations of the sorbents. A proper account of these transformations allows for the sorption process to be optimized. The data on Pb2+, Cd2+, Cr3+ sorption under static conditions (24-h contact of Mg3 (PO42. 6H2O, MgNH4PO4. H2O, with solutions at 20oC and under dynamic conditions were obtained and the sorption behaviors of the metal ions were investigated in response to the sorbents used. It was found that Mg3 (PO42. 6H2O was the best sorbent for Pb2+, Cd2+, Cr3+ under dynamic conditions.

  7. Synthesis and crystal structure of rare earth complexes with o-nitrobenzoic acid and N, N-dimethylformamide

    Science.gov (United States)

    Zhao, Lifang; Chen, Yashao; Bao, Lin

    2010-03-01

    The rare-earth compound [Ce 0.5Sm 0.5( o-NBA) 3(DMF) 2] 2 (where o-NBA = o-nitrobenzoic acid, DMF = N, N-dimethylformamide) has been synthesized and structurally characterized. The crystal structure of the compound is characterized by Fourier transfer infrared spectroscopy (FT-IR), fluorescent emission spectroscopy (FES) and single-crystal X-ray diffraction. The results show that the compound crystallizes in a triclinic system, space group P-1 with a = 11.8284 (6) Å, b = 12.5082 (7) Å, c = 13.0203 (7) Å, α = 63.9650 (10)°, β = 66.3900 (10)°, γ = 71.7380 (10)°, V = 1563.7 (14) Å 3, Dc = 1.677 g/cm 3, Z = 1, F(0 0 0) = 790. Each Ln (III) atom is bridged by four o-nitro-benzoates and chelated by one o-nitrobenzoate. The Ln (III) atom is eight-coordinated by six oxygen atoms from five o-nitro-benzoates and two oxygen atoms from two DMF molecules. Hydrogen bonds and aromatic π⋯ π stacking interactions assemble the compound into a three-dimensional network. Luminescence measurement shows that the compound emits fluorescence.

  8. Effect of Ba in the glass characteristics of cesium loaded iron phosphate glasses

    International Nuclear Information System (INIS)

    Joseph, Kitheri; Asuvathraman, R.; Vasudeva Rao, P.R.

    2015-01-01

    Radioactive 137 Cs extracted from high level nuclear waste, when immobilized in a suitable matrix can be used as a γsource in medical industry. Iron phosphate glass (IPG) is one of a suitable matrix for the immobilization of 137 Cs prior to the immobilization of 137 Cs in IPG, it is essential to optimize the immobilization conditions using natural (inactive) cesium. Glass characteristics of inactive Cs loaded iron phosphate glasses were already explored in our earlier studies. However, the change in glass characteristics of 137 Cs loaded iron phosphate glass to 137 Ba loaded iron phosphate glass need to be studied before the immobilization of 137 Cs in iron phosphate glass as 137 Cs transforms to 137 Ba due to nuclear transmutation ( 137 Cs(β,γ) 137 Ba). This paper reports the studies on such a behaviour by incorporating inactive Ba in cesium loaded iron phosphate glasses. Cs and Ba loaded iron phosphate glasses were prepared by melt quench technique in air using appropriate amounts of Fe 2 O 3 , NH 4 H 2 PO 4 , Ba(OH) 2.8 H 2 O and Cs 2 CO 3 . The chemicals were added such that the glass formed possesses the batch composition of (a) 21.4 wt. % Fe 2 O 3 -45 wt. % Cs 2 O-5 wt % BaO-P 2 O 5 (henceforth referred as IP50Cs45Ba5); (b) 21.4 wt. % Fe 2 O 3 -25 wt. % Cs 2 O-25 wt % BaO-P 2 O5 (henceforth referred as IP50Cs25Ba25). The thermal expansion measurements were also carried out using a home-built quartz push-rod dilatometer. The data related to change in thermal expansion behaviour, glass forming ability, glass stability and structural changes in phosphate network due to the partial replacement of Cs with Ba will also be discussed. (author)

  9. Magnetoelastic properties of the quantum-spin-ice candidate Yb{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Stoeter, T.; Wang, Z.S.; Wosnitza, J. [SFB 1143 (Germany); TUD/IFP, Dresden (Germany); HZDR, Dresden (Germany); Doerr, M.; Granovsky, S. [SFB 1143 (Germany); TUD/IFP, Dresden (Germany); Erfanifam, S.; Green, E. [HZDR, Dresden (Germany); Zherlitsyn, S. [SFB 1143 (Germany); HZDR, Dresden (Germany); Maljuk, A.; Wurmehl, S. [SFB 1143 (Germany); IFW, Dresden (Germany)

    2016-07-01

    Intriguing phenomena such as the occurrence of magnetic monopoles and a wide variety of ground states are associated to magnetic frustration. In a number of cases, elastic effects, e.g. lattice distortions, may result in the lifting of degeneracies or the appearance of new magnetic states. The rare-earth titanate Yb{sub 2}Ti{sub 2}O{sub 7}, where the magnetic Yb{sup 3+} ions form a pyrochlore spin network, is a prime example of a geometrically frustrated material, with numerous field-induced phases and strong ferromagnetic correlations below 170 mK. In order to characterize the magneto-elastic coupling in this material, we have investigated the thermal expansion, magnetostriction, and sound propagation in different dilution refrigerators between 60 mK and 1.5 K and large applied magnetic fields. At around 170 mK we find distinct anomalies in the expansion coefficient, acoustic properties, as well as the specific heat. Lattice anomalies in field hint to additional low temperature phases.

  10. The production of rare earth elements group via tributyl phosphate extraction and precipitation stripping using oxalic acid

    OpenAIRE

    Jorjani, Esmaeil; Shahbazi, Malek

    2016-01-01

    In this study, solvent extraction and precipitation stripping were used to produce rare earth elements (REEs). Tributyl phosphate (TBP) was used to extract yttrium, lanthanum, cerium, and neodymium from an aqueous solution produced by nitric acid leaching of apatite concentrate. In the extraction stage, the effects of TBP concentration, pH, contact time, temperature, and phase ratio were investigated. The results show that about 95%, 90%, 87% and 80% of neodymium, cerium, lanthanum, and yttri...

  11. Simultaneous stabilization/solidification of Mn2+ and NH4+-N from electrolytic manganese residue using MgO and different phosphate resource.

    Science.gov (United States)

    Shu, Jiancheng; Wu, Haiping; Liu, Renlong; Liu, Zuohua; Li, Bing; Chen, Mengjun; Tao, Changyuan

    2018-02-01

    This study examined simultaneous stabilization and solidification (S/S) of Mn 2+ and NH 4 + -N from electrolytic manganese residue (EMR) using MgO and different phosphate resource. The characteristics of EMR NH 4 + -N and Mn 2+ S/S behavior, S/S mechanisms, leaching test and economic analysis, were investigated. The results show that the S/S efficiency of Mn 2+ and NH 4 + -N could reach 91.58% and 99.98%, respectively, and the pH value is 8.75 when the molar ratio of Mg:P is 3:1 and the dose of PM (MgO and Na 3 PO 4 ·12H 2 O) is 8wt%. In this process, Mn 2+ could mainly be stabilized in the forms of Mn(H 2 PO 4 ) 2 ·2H 2 O, Mn 3 (PO 4 ) 2 ·3H 2 O, Mn(OH) 2 , and MnOOH, and NH 4 + -N in the form of NH 4 MgPO 4 ·6H 2 O. Economic evaluation indicates that using PM process has a lower cost than HPM and HOM process for the S/S of Mn 2+ and NH 4 + -N from EMR at the same stabilization agent dose. Leaching test values of all the measured metals are within the permitted level for the GB8978-1996 test suggested when the dose of PM, HPM and HOM is 8wt%. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Hydrothermal synthesis, characterization, formation mechanism and electrochemical property of V3O7.H2O single-crystal nanobelts

    International Nuclear Information System (INIS)

    Zhang Yifu; Liu Xinghai; Xie Guangyong; Yu Lei; Yi Shengping; Hu Mingjie; Huang Chi

    2010-01-01

    Single-crystal V 3 O 7 .H 2 O nanobelts have been successfully synthesized in a large-scale by ethanol reducing of the commercial V 2 O 5 powder via a facile hydrothermal approach, without any templates and surfactants. The as-prepared V 3 O 7 .H 2 O nanobelts are up to several tens of micrometers in length, about 100 nm in width and about 20 nm in thickness in average, respectively. The 'Hydrating-Reducing-Exfoliating-Splitting' (HRES) mechanism was proposed to describe the formation of the V 3 O 7 .H 2 O nanobelts. In our research progress, it was found that the ratio of EtOH/H 2 O, the reaction time and categories of the reducing agents had significant effects on the morphology and composition of as-obtained products. Furthermore, the electrochemical properties of V 3 O 7 .H 2 O nanobelts were preformed and the results revealed that a lithium battery using those nanobelts as the positive electrode exhibited a high initial discharge capacity of 373 mAh/g.

  13. Vibrational spectra and lattice instabilities in the high-T/sub c/ superconductors YBa2Cu3O7 and GdBa2Cu3O7

    International Nuclear Information System (INIS)

    Bozovic, I.; Mitzi, D.; Beasley, M.

    1987-01-01

    The exceptionally high T/sub c/ of layered cuprates was proposed recently as originating from electronically driven structural instabilities. We have studied the infrared and Raman spectra of YBa 2 Cu 3 O/sub 7-//sub δ/ and GdBa 2 Cu 3 O/sub 7-//sub δ/ over a broad range of temperatures, from 10 to 300 K. We observed neither mode softening nor any other spectroscopic signature of lattice instabilities

  14. Magnesium prevents phosphate-induced vascular calcification via TRPM7 and Pit-1 in an aortic tissue culture model.

    Science.gov (United States)

    Sonou, Tomohiro; Ohya, Masaki; Yashiro, Mitsuru; Masumoto, Asuka; Nakashima, Yuri; Ito, Teppei; Mima, Toru; Negi, Shigeo; Kimura-Suda, Hiromi; Shigematsu, Takashi

    2017-06-01

    Previous clinical and experimental studies have indicated that magnesium may prevent vascular calcification (VC), but mechanistic characterization has not been reported. This study investigated the influence of increasing magnesium concentrations on VC in a rat aortic tissue culture model. Aortic segments from male Sprague-Dawley rats were incubated in serum-supplemented high-phosphate medium for 10 days. The magnesium concentration in this medium was increased to demonstrate its role in preventing VC, which was assessed by imaging and spectroscopy. The mineral composition of the calcification was analyzed using Fourier transform infrared (FTIR) spectroscopic imaging, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) mapping. Magnesium supplementation of high-phosphate medium dose-dependently suppressed VC (quantified as aortic calcium content), and almost ablated it at 2.4 mm magnesium. The FTIR images and SEM-EDX maps indicated that the distribution of phosphate (as hydroxyapatite), phosphorus and Mg corresponded with calcium content in the aortic ring and VC. The inhibitory effect of magnesium supplementation on VC was partially reduced by 2-aminoethoxy-diphenylborate, an inhibitor of TRPM7. Furthermore, phosphate transporter-1 (Pit-1) protein expression was increased in tissues cultured in HP medium and was gradually-and dose dependently-decreased by magnesium. We conclude that a mechanism involving TRPM7 and Pit-1 underpins the magnesium-mediated reversal of high-phosphate-associated VC.

  15. Absorption spectra and speciation of plutonium(VI) with phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Weger, H.T.; Reed, D.

    1996-02-01

    Plutonium(VI)-phosphate species in aqueous solution, at pH < 2.4, formed two species: PuO{sub 2}H{sub 2}PO{sub 4}{sup +} (characterized by an 835 nm absorption band) and the solid phase PuO{sub 2}(H{sub 2}PO{sub 4}){sub 2}. The stability constant {beta} for the PuO{sub 2}H{sub 2}PO{sub 4}{sup +} species was determined to be log {beta} = 2.1 {+-} 0.1 (ionic strength = 0.6--0.9 M) and log {beta}{sup T} = 2.6 {+-} 0.15 (zero ionic strength). Four Pu(VI)-phosphate species (absorption bands at 842, 846, 857, and 866 nm) formed at pH = 2.4 to 12.2 and are characterized by polynuclear behavior, the formation of precipitates, and colloidal properties. The 842 and 846 nm species are believed to be [PuO{sub 2}(HPO{sub 4}){sub m}]{sub n} and [PuO{sub 2}(NaPO{sub 4}){sub m}]{sub n}. The 857 and 866 nm species area as yet unidentified. The speciation of plutonium with phosphate is of interest to radionuclide migration studies because phosphate is present in many groundwaters and may be used as an actinide getter in nuclear waste disposal. An actinide getter is a complexing agent that forms insoluble phases with actinides, thereby reducing their migration.

  16. Mechanistic studies of 3-deoxy-D-manno-octulosonic acid 8-phosphate synthase

    International Nuclear Information System (INIS)

    Dotson, G.D.; Woodard, R.W.

    1994-01-01

    The enzyme 3-deOXY-D-manno-octulosonic acid 8-phosphate synthase (KDO 8-P synthase) catalyses the condensation of arabinose 5-phosphate (A 5-P) with phosphoenolpyruvate (PEP) to give the unique eight-carbon acidic sugar 3-deoxy-D-nianno-octulosonic acid 8-phosphate (KDO 8-P) found only in gram-negative bacteria and required for lipid A maturation and cellular growth. The E. coli gene kdsA that encodes KDO 8-P synthase has been amplified by standard PCR methodologies. The synthetic gene, subcloned into the expression vector pT7-7 was used to infect E. coli BL 21 (DE 3). Purification of crude supernatant from this transformant on Q Sepharose yields >200 mg of near-homogeneous KDO 8-P synthase per liter of cell culture. To explore the mechanism of KDO 8-P synthase, we prepared (E)- and (Z)-(3 2 H)PEP, (2- 13 C)PEP, and (2- 13 C, 18 O)PEP chemically from the appropriately labeled 3-bromopyruvates by reaction with trimethylphosphite under Perkow reaction conditions. Our 1 H-NMR analysis of the stereochemistry at C3 of the KDO 8-Ps, obtained by separate incubation of (E)- and (Z)-(3- 2 H)PEP with A 5-P in the presence of KDO 8-P synthase, demonstrated that the reaction is stereospecific with respect to both the C3 of PEP and the C1 carbonyl of A 5-P. (Z)-(3- 2 H)PEP gave predominantly (3S)-(3 2 H)KDO 8-P and (E)-(3- 2 H)PEP gave predominantly (3R)-(3 2 H)KDO-8P, which indicates condensation of the si face of PEP upon the re face of A 5-P-an orientation analogous to that seen with the similar aldehyde Iyase DAH 7-P synthase. The fate of the enolic oxygen of (2- 13 C, 18 O)PEP, during the course of the KDO 8-P synthase-catalyzed reaction as monitored by both 13 C- and 31 P-NMR spectroscopy demonstrated that the inorganic phosphate (Pi) and not the KDO 8-P contained the 18 O

  17. Mechanistic studies of 3-deoxy-D-manno-octulosonic acid 8-phosphate synthase

    Energy Technology Data Exchange (ETDEWEB)

    Dotson, G.D.; Woodard, R.W. [Univ. of Michigan, Ann Arbor, MI (United States)

    1994-12-01

    The enzyme 3-deOXY-D-manno-octulosonic acid 8-phosphate synthase (KDO 8-P synthase) catalyses the condensation of arabinose 5-phosphate (A 5-P) with phosphoenolpyruvate (PEP) to give the unique eight-carbon acidic sugar 3-deoxy-D-nianno-octulosonic acid 8-phosphate (KDO 8-P) found only in gram-negative bacteria and required for lipid A maturation and cellular growth. The E. coli gene kdsA that encodes KDO 8-P synthase has been amplified by standard PCR methodologies. The synthetic gene, subcloned into the expression vector pT7-7 was used to infect E. coli BL 21 (DE 3). Purification of crude supernatant from this transformant on Q Sepharose yields >200 mg of near-homogeneous KDO 8-P synthase per liter of cell culture. To explore the mechanism of KDO 8-P synthase, we prepared (E)- and (Z)-(3{sup 2}H)PEP, (2-{sup 13}C)PEP, and (2-{sup 13}C,{sup 18}O)PEP chemically from the appropriately labeled 3-bromopyruvates by reaction with trimethylphosphite under Perkow reaction conditions. Our {sup 1}H-NMR analysis of the stereochemistry at C3 of the KDO 8-Ps, obtained by separate incubation of (E)- and (Z)-(3-{sup 2}H)PEP with A 5-P in the presence of KDO 8-P synthase, demonstrated that the reaction is stereospecific with respect to both the C3 of PEP and the C1 carbonyl of A 5-P. (Z)-(3-{sup 2}H)PEP gave predominantly (3S)-(3{sup 2}H)KDO 8-P and (E)-(3-{sup 2}H)PEP gave predominantly (3R)-(3{sup 2}H)KDO-8P, which indicates condensation of the si face of PEP upon the re face of A 5-P-an orientation analogous to that seen with the similar aldehyde Iyase DAH 7-P synthase. The fate of the enolic oxygen of (2-{sup 13}C, {sup 18}O)PEP, during the course of the KDO 8-P synthase-catalyzed reaction as monitored by both {sup 13}C- and {sup 31}P-NMR spectroscopy demonstrated that the inorganic phosphate (Pi) and not the KDO 8-P contained the {sup 18}O.

  18. Superconducting properties and microstructure of YBa2Cu3O7-δ/PrBa2Cu3O7-δ superlattices

    International Nuclear Information System (INIS)

    Lowndes, D.H.; Norton, D.P.; Zheng, X.Y.; Zhu, Shen

    1991-10-01

    Epitaxial YBa 2 Cu 3 O 7-δ /PrBa 2 Cu 3 O 7-δ (YBCO/PBCO) superlattices are tools for systematic, fundamental studies of high-temperature superconductivity. The variation of T c in YBCO/PBCO superlattices can be understood as arising from changes in the interlayer phase coupling between YBCO layers that are highly two-dimensional when they are very thin (∼1--2 c-axis unit cells) and completely isolated from each other. Single-cell-thick YBCO layers, containing isolated pairs of CuO 2 planes, are found to be superconducting at T c ∼ 20 K, in a PBCO matrix. The resistance in the superconducting transition region scales with temperature as expected for the (flux flow) resistance produced by thermally generated 2D vortices, or for a 2D array of superconducting weak links. Relative to both thin-film and single-crystal HTSc specimens, the thin superconducting layers in YBCO/PBCO superlattices exhibit a greatly expanded temperature range over which characteristic 2D dissipation can be observed, as a consequence of the enhanced anisotropy and reduced dimensionality of the YBCO layers. Scanning tunneling microscope studies reveal that YBCO films and YBCO/PBCO superlattices grow unit cell-by-unit cell by a terraced-island growth mechanism. On miscut, near-(001) substrates the terraces are epitaxially aligned with the substrate crystal lattice and spiral growth structures (screw dislocation-mediated growth) are not seen. These observations explain the steps or ''kinks'' that are seen in cross-section Z-contrast TEM images of YBCO/PBCO superlattices. The kinks may correspond physically to regions where the supercurrent must tunnel along the c- axis, and thus may be weak-link barriers. 31 refs., 7 figs

  19. Conductivity fluctuation and superconducting parameters of the YBa{sub 2}Cu{sub 3-} {sub x} (PO{sub 4}) {sub x} O{sub 7-} {sub {delta}} material

    Energy Technology Data Exchange (ETDEWEB)

    Rojas Sarmiento, M.P. [Grupo de Fisica de Nuevos Materiales, Departamento de Fisica, Universidad Nacional de Colombia, AA 14490, Bogota DC (Colombia); Uribe Laverde, M.A. [Grupo de Fisica de Nuevos Materiales, Departamento de Fisica, Universidad Nacional de Colombia, AA 14490, Bogota DC (Colombia); Vera Lopez, E. [Grupo de Superficies, Electroquimica y Corrosion, UPTC, Tunja (Colombia); Landinez Tellez, D.A. [Grupo de Fisica de Nuevos Materiales, Departamento de Fisica, Universidad Nacional de Colombia, AA 14490, Bogota DC (Colombia); Roa-Rojas, J. [Grupo de Fisica de Nuevos Materiales, Departamento de Fisica, Universidad Nacional de Colombia, AA 14490, Bogota DC (Colombia)]. E-mail: jroar@unal.edu.co

    2007-09-01

    Synthesis of the YBa{sub 2}Cu{sub 3-} {sub x} (PO{sub 4}) {sub x} O{sub 7-} {sub {delta}} superconducting material by the standard solid-state reaction is reported. DC resistivity measurements reveal the improvement of the critical temperature (T {sub C}) when substitution of phosphate in the Cu sites is performed. A bulk T {sub C}=97 K was determined by the criterion of the maximum in the temperature derivative of electrical resistivity. Structure characterization by means the X-ray diffraction technique shows the crystalline appropriated distribution of PO{sub 4} into the CuO{sub 2} superconducting planes. In order to examine the effect of phosphates on the pairing mechanism close to T {sub C}, conductivity fluctuation analysis was performed by the method of logarithmic temperature derivative of the conductivity excess. We found the occurrence of Gaussian-like fluctuations. The correlations of the critical exponents with the dimensionality of the fluctuation system for each Gaussian regime were performed by using the Aslamazov-Larkin theory. The Ginzburg number for this superconducting material is predicted and the critical magnetic fields, critical current density and the jump in the specific heat at the critical temperature are theoretically determined.

  20. Radiation defects in SrB4O7:Eu2+ crystals

    International Nuclear Information System (INIS)

    Yavetskiy, R.P.; Dolzhenkova, E.F.; Tolmachev, A.V.; Parkhomenko, S.V.; Baumer, V.N.; Prosvirnin, A.L.

    2007-01-01

    Radiation-induced defects in SrB 4 O 7 :Eu 2+ (0.033 at.%) single crystal irradiated with γ and X-ray quanta has been studied. The induced optical absorption in the 400-700 nm region has been ascribed to F + centers. The Eu 2+ ions have been shown to act simultaneously as traps and as radiative recombination centers of charge carriers. Basing on the thermally stimulated luminescence (TSL), optical absorption and photoluminescence studies of SrB 4 O 7 :Eu 2+ crystals, a TSL mechanism has been proposed associated with the decay of F + centers being in non-equivalent crystallographic positions followed by radiative recombination of charge carriers on europium ions. Various positions of localization of the radiation-induced defects in the SrB 4 O 7 crystal structure have been discussed

  1. Electronic structure of layered ferroelectric high-k titanate La{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V V [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Gavrilova, T A [Laboratory of Electron Microscopy and Submicron Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Grivel, J-C [Materials Research Department, National Laboratory for Sustainable Energy, Technical University of Denmark, Frederiksborgvej 399, DK-4000, Roskilde (Denmark); Kesler, V G, E-mail: atuchin@thermo.isp.nsc.r [Laboratory of Physical Bases of Integrated Microelectronics, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

    2009-02-07

    The electronic structure of binary titanate La{sub 2}Ti{sub 2}O{sub 7} has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La{sub 2}Ti{sub 2}O{sub 7} are determined as alpha{sub Ti} = 872.4 and alpha{sub O} = 1042.3 eV. Chemical bonding effects have been discussed with binding energy (BE) differences DELTA{sub Ti} = (BE O 1s - BE Ti 2p{sub 3/2}) = 71.6 eV and DELTA{sub La} = (BE La 3d{sub 5/2} - BE O 1s) = 304.7 eV as key parameters in comparison with those in several titanium- and lanthanum-bearing oxides.

  2. Characterisation and Properties of Lithium Disilicate Glass Ceramics in the SiO2-Li2O-K2O-Al2O3 System for Dental Applications

    Directory of Open Access Journals (Sweden)

    Naruporn Monmaturapoj

    2013-01-01

    Full Text Available This work proposes four different glass formulas derived from the SiO2-Li2O-K2O-Al2O3 system to investigate the effect of glass composition on their crystal formations and properties. Glass LD1 was SiO2-Li2O-K2O-Al2O3 system with the addition of P2O5 and CaF2 as nucleating agents. In Glass LD2, a slight amount of MgO was mixed in order to increase the viscosity of the melting glass. Finally, the important factor of Si : Li ratio was increased in Glasses LD3 and LD4 with compositions otherwise the same as LD1 and LD2. The results found that P2O5 and CaF2 served as a nucleating site for lithium phosphate and fluorapatite to encourage heterogenous nucleation and produce a fine-grained interlocking microstructure of lithium disilicate glass ceramics. MgO content in this system seemed to increase the viscosity of the melting glass and thermal expansion coefficient including the chemical solubility. Increasing the Si : Li ratio in glass compositions resulted in the change of the microstructure of Li2Si2O5 crystals.

  3. Long afterglow properties of Eu2+/Mn2+ doped Zn2GeO4

    International Nuclear Information System (INIS)

    Wan, Minhua; Wang, Yinhai; Wang, Xiansheng; Zhao, Hui; Li, Hailing; Wang, Cheng

    2014-01-01

    Zn 2 GeO 4 :Eu 2+ 0.01 and Zn 2 GeO 4 :Mn 2+ 0.01 long afterglow phosphors were synthesized via a high temperature solid state reaction. X-ray diffraction (XRD), afterglow spectra, decay curves and thermoluminescence curves were utilized to characterize the samples. The X-ray diffraction phases indicate that the doping of small amount of transition metal ions or rare earth ions has no significant influence on the crystal structure of Zn 2 GeO 4 . According to the afterglow spectra, we found that the Zn 2 GeO 4 :Eu 2+ 0.01 exhibits a broad band emission with a peak at 474 nm, which could be ascribed to Eu 2+ transition between 4f 6 5d 1 and 4f 7 electron configurations. The Zn 2 GeO 4 :Mn 2+ 0.01 shows a narrow band emission peaking at 532 nm corresponding to the characteristic transition of Mn 2+ ( 4 T 1 → 6 A 1 ). The thermoluminescence (TL) curves above room temperature are employed for the discussion of the origin of the traps and the mechanism of the persistent luminescence. The results indicate that Zn 2 GeO 4 may be an excellent host material for the rare earth ions or transition metal ions long afterglows. -- Highlights: • Zn 2 GeO 4 :Eu 2+ 0.01 and Zn 2 GeO 4 :Mn 2+ 0.01 long afterglow phosphors were synthesized. • Found that these phosphors possess a persistent luminescence property. • The long afterglow spectra were measured. • Found that these phosphors possess a trap level by thermoluminescence

  4. Band structure of metallic pyrochlore ruthenates Bi2Ru2O7 and Pb2Ru2O/sub 6.5/

    International Nuclear Information System (INIS)

    Hsu, W.Y.; Kasowski, R.V.; Miller, T.; Chiang, T.

    1988-01-01

    The band structure of Bi 2 Ru 2 O 7 and Pb 2 Ru 2 O/sub 6.5/ has been computed self-consistently from first principles for the first time by the pseudofunction method. We discover that the 6s bands of Bi and Pb are very deep and unlikely to contribute to the metallic behavior as previously believed. The unoccupied 6p bands, however, are only several eV above the Fermi energy and are mixed with the Ru 4d band at the Fermi surface via the framework O atoms, leading to band conduction and delocalized magnetic moments. The predicted location of the 6s bands and the location and width of the O 2p band are confirmed by synchrotron radiation and ultraviolet electron spectroscopy of single crystals

  5. Synthesis, crystal structure, and vibrational spectroscopic and UV-visible studies of Cs{sub 2}MnP{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Kaoua, Saida; Krimi, Saida [LPCMI, Faculte des Sciences Aien Chok, UH2C, Casablanca (Morocco); Pechev, Stanislav; Gravereau, Pierre; Chaminade, Jean-Pierre [CNRS, Universite de Bordeaux, ICMCB, 87, Avenue du Dr. A. Schweitzer, Pessac (France); Couzi, Michel [CNRS, Universite de Bordeaux, ISM, UMR 5255, F-33400 Talence (France); El Jazouli, Abdelaziz, E-mail: eljazouli_abdelaziz@yahoo.fr [LCMS, URAC 17, Faculte des Sciences Ben M' Sik, UH2MC, Casablanca (Morocco)

    2013-02-15

    A new member of the A{sub 2}MP{sub 2}O{sub 7} diphosphate family, Cs{sub 2}MnP{sub 2}O{sub 7}, has been synthesized and structurally characterized. The crystal structure was determined by single crystal X-Ray diffraction. Cs{sub 2}MnP{sub 2}O{sub 7} crystallizes in the orthorhombic system, space group Pnma ( Music-Sharp-Sign 62), with the unit cell parameters a=16.3398(3), b=5.3872(1), c=9.8872(2) A, Z=4 and V=870.33(3) A{sup 3}. The structure parameters were refined to a final R{sub 1}/wR{sub 2}=0.0194/0.0441 for 1650 observed reflections. The 2D framework of Cs{sub 2}MnP{sub 2}O{sub 7} structure consists of P{sub 2}O{sub 7} and MnO{sub 5} units. The corner-shared MnO{sub 5} and P{sub 2}O{sub 7} units are alternately arranged along the b axis to form [(MnO)P{sub 2}O{sub 7}]{sub {infinity}} chains. These chains are interconnected by an oxygen atom to form sheets parallel to the (b, c) plane. The cesium atoms are located between the sheets in 9- and 10-fold coordinated sites. The infrared and Raman vibrational spectra have been investigated. A factor group analysis leads to the determination of internal modes of (P{sub 2}O{sub 7}) groups. UV-visible spectrum consists of weak bands, between 340 and 700 nm, assigned to the forbidden d-d transitions of Mn{sup 2+} ion, and of a strong band around 250 nm, attributed to the O--Mn charge transfer. - Graphical abstract: Structure of Cs{sub 2}MnP{sub 2}O{sub 7}: The 2D structure of Cs{sub 2}MnP{sub 2}O{sub 7} is built from P{sub 2}O{sub 7} diphosphate groups and MnO{sub 5} square pyramids which share corners and form [(MnO)P{sub 2}O{sub 7}]{sub {infinity}} chains along b axis. These chains are interconnected by an oxygen atom to form wavy (MnP{sub 2}O{sub 7}){sup 2-} sheets parallel to the (b, c) plane. The cesium ions are located between these sheets in the inter-layers space, in zigzag positions. Highlights: Black-Right-Pointing-Pointer A new diphosphate, Cs{sub 2}MnP{sub 2}O{sub 7}, has been synthesized and structurally

  6. Phase studies in the CdO-Al2O3-TiO2 system: radioactive waste implications

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, P E.D.; Koutsoutis, M S

    1985-10-01

    With the study of new compounds such as CaTi3Al8O19, and the isotypic RETi2Al9O19 (where RE = light rare earth), the question arose as to whether a cadmium analogue existed. The relative stability of the aforementioned phases to hydrothermal water further suggested the cadmium analogue as a host phase for radioactive wastes that might contain cadmium as a neutron poison. Ti-Al(-Fe) matrix compositions are potentially useful as crystalline radwaste hosts. Experimental details are given for the preparation of the cadmium compounds. The subsolidus region of the CdO-Al2O3-TiO2 diagram at 1100C is shown. The compound CdTi3Al8O19 does not exist, but a new orthorhombic ternary compound CdTi2Al2O8 was found. The complete X-ray powder data for CdTi2Al2O8 are presented. CdAl4O7 was confirmed to decompose at approx. 1180C and melts occur in the centre of the diagram at approx. 1200C. At temperatures below approx. 900C, el-Al2O3 and the ilmenite form of CdTiO3 form; the latter suddenly converts to the perovskite form between 900 and 925C. Both forms of CdTiO3 and CdTi2Al2O8 were water resistant and survived unchanged when held in water at 150C for one month in teflon-lined stainless steel bombs.

  7. Quasi-homoepitaxial growth of a-axis oriented PrBa sub 2 Cu sub 3 O sub 7 sub - subdelta thick film on (100) YBa sub 2 Cu sub 3 O sub 7 sub - subdelta single crystal

    CERN Document Server

    Sato, M; Morishita, T

    2003-01-01

    The structural characterizations of the quasi-homoepitaxial growth of a-axis oriented PrBa sub 2 Cu sub 3 O sub 7 sub - subdelta thick film grown on (100) YBa sub 2 Cu sub 3 O sub 7 sub - subdelta single crystal were investigated in comparison with those of the film grown on (001) YBa sub 2 Cu sub 3 O sub 7 sub - subdelta single crystal. The a-axis oriented PrBa sub 2 Cu sub 3 O sub 7 sub - subdelta films, expected to be a barrier layer, were prepared using a dc-95 MHz hybrid plasma sputtering on (100) and (001) YBa sub 2 Cu sub 3 O sub 7 sub - subdelta single crystals that are superconducting ground planes. The atomic force microscopy image revealed that the surfaces of 700-nm-thick a-axis PrBa sub 2 Cu sub 3 O sub 7 sub - subdelta films on (100) YBa sub 2 Cu sub 3 O sub 7 sub - subdelta single crystals were smooth with a mean roughness of 2.8 nm. X-ray diffraction scans showed that a-axis PrBa sub 2 Cu sub 3 O sub 7 sub - subdelta films deposited on (100) YBa sub 2 Cu sub 3 O sub 7 sub - subdelta single cry...

  8. On the structure of rare earth periodates of LnIO5x4H2O (Ln=Pr-Lu, Y)

    International Nuclear Information System (INIS)

    Shamraj, N.B.; Varfolomeev, M.B.; Saf'yanov, Yu.N.; Kuz'min, Eh.A.; Ilyukhin, V.V.; AN SSSR, Moscow. Inst. Kristallografii)

    1977-01-01

    The crystal structure of three representatives of an isotypic series of monoclinic periodates of rare earth elements in the series from Pr to Lu and Y was deciphered. The monoclinic cell for all LnIO 5 x4H 2 O contains Z=4 formula units. The architectural motif consists in layers of octahedra of IO 4 (OH) 2 and polyhedra of LnO 5 (H 2 O 3 ) parallel to the (100) plane. Adhesion between the layers is achieved through H-bonds

  9. Effect of alkali earth oxides on hydroxy-carbonated apatite nano layer formation for SiO2-BaO-CaO-Na2O-P2O5 glass system

    Science.gov (United States)

    Kiran, P.; Ramakrishna, V.; Shashikala, H. D.; Udayashankar, N. K.

    2017-11-01

    Barium soda lime phosphosilicate [(58SiO2-(32 - x)BaO- xCao-6Na2O-4P2O5 (where x = 15, 20, 25 and 30 mol%)] samples were synthesised using conventional sol-gel method at 700 °C sintering temperature. Thermal, structural properties were studied using thermo gravimetric analysis and differential thermal analysis, X-ray diffraction, scanning electron microscopy, fourier transform infrared and Raman spectroscopy. Using Raman spectra non-bridging oxygen concentrations were estimated. The hydroxy-carbonated apatite (HCA) layer formation on samples was analysed for 7 days using simulated body fluid (SBF) soaked samples. The growth of HCA layers self-assembled on the sample surface was discussed as a function of NBO/BO ratio. Results indicated that the number of Ca2+ ions released into SBF solution in dissolution process and weight loss of SB-treated samples vary with NBO/BO ratio. The changes in NBO/BO ratios were observed to be proportional to HCA forming ability of barium soda lime phosphosilicate glasses.

  10. Tris(dibenzoylmethanido-κ2O,O′[(6S,8S-(+-7,7-dimethyl-3-(2-pyridyl-5,6,7,8-tetrahydro-6,8-methanoisoquinoline-κ2N,N′]gadolinium(III

    Directory of Open Access Journals (Sweden)

    Xi-Li Li

    2009-09-01

    Full Text Available In the title compound, [Gd(C15H11O23(C17H18N2], the GdIII atom is coordinated by six O atoms from three β-diketonate ligands and two N atoms from a chiral ligand LS,S-(+-7,7-dimethyl-3-(2-pyridyl-5,6,7,8-tetrahydro-6,8-methanoisoquinoline, in a coordination geometry best described as distorted square-antiprismatic.

  11. A new langbeinite-type phosphate: K2AlSn(PO43

    Directory of Open Access Journals (Sweden)

    Dan Zhao

    2011-10-01

    Full Text Available Single crystals of the title compound, dipotassium aluminium tin(IV tris[phosphate(V], K2AlSn(PO43, were synthesized by a high temperature reaction in a platinum crucible. In the structure, the AlIII and SnIV atoms occupy the same site on a threefold rotation axis with occupational disorder in a 1:1 ratio. In the three-dimensional structure, Al/SnO6 octahedra and PO4 tetrahedra are interconnected via their vertices, yielding a [Al/SnP3O12]n framework. The K atoms (site symmetry 3 reside in the large cavities delimited by the [Al/SnP3O12]n framework, and are surrounded by 12 O atoms.

  12. Electronic structure of layered ferroelectric high-k titanate Pr{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V.V., E-mail: atuchin@thermo.isp.nsc.ru [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Gavrilova, T.A. [Laboratory of Nanodiagnostics and Nanolithography, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Grivel, J.-C. [Materials Research Division, National Laboratory for Sustainable Energy, Technical University of Denmark, Frederiksborgvej 399, DK-4000, Roskilde (Denmark); Kesler, V.G. [Laboratory of Physical Bases of Integrated Microelectronics, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Troitskaia, I.B. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

    2012-11-15

    The spectroscopic parameters and electronic structure of binary titanate Pr{sub 2}Ti{sub 2}O{sub 7} have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Pr{sub 2}Ti{sub 2}O{sub 7} have been determined as {alpha}{sub Ti}=872.8 and {alpha}{sub O}=1042.3 eV. Variations of cation-anion bond ionicity have been discussed using binding energy differences {Delta}{sub Ti}=(BE O 1s-BE Ti 2p{sub 3/2})=71.6 eV and {Delta}{sub Pr}=BE(Pr 3d{sub 5/2})-BE(O 1s)=403.8 eV as key parameters in comparison with those of other titanium- and praseodymium-bearing oxides. Highlights: Black-Right-Pointing-Pointer Solid state synthesis of polar titanate Pr{sub 2}Ti{sub 2}O{sub 7}. Black-Right-Pointing-Pointer Structural and spectroscopic properties and electronic structure determination. Black-Right-Pointing-Pointer Ti-O and Pr-O bonding analysis using Ti 2p{sub 3/2}, Pr 3d{sub 5/2} and O 1s core levels.

  13. Effect of RE (Nd3+, Sm3+) oxide on structural, optical properties of Na2O-Li2O-ZnO-B2O3 glass system

    Science.gov (United States)

    Hivrekar, Mahesh M.; Bhoyar, D. N.; Mande, V. K.; Dhole, V. V.; Solunke, M. B.; Jadhav, K. M.

    2018-05-01

    Zinc borate glass activated with rare earth oxide (Nd2O3, Sm2O3) of Na2O-Li2O-ZnO-B2O3 quaternary system has been prepared successfully by melt quenching method. The nucleation and growth of RE oxide were controlled temperature range 950-1000° C and rapid cooling at room temperature. The physical, structural and optical properties were characterized by using X-ray diffraction (XRD), SEM, Ultraviolet-visible spectroscopy (UV-Vis). XRD and SEM studies confirmed the amorphous nature, surface morphology of prepared zinc borate glass. The physical parameters like density, molar volume, molar mass of Nd3+, Sm3+ doped borate glass are summarized in the present article. The optical absorption spectra along with tauc's plot are presented. The optical energy band gap increases due to the addition of rare earth oxide confirming the role of network modifier.

  14. Optical Properties and Photoactivity of The Pigmentary TiO2 Doped with P2O5, K2O, Al2O3 and Sb2O3

    International Nuclear Information System (INIS)

    Glen, M; Grzmil, B

    2011-01-01

    The influence of the increasing content of antimony calculated to Sb 2 O 3 (0.08-0.57 mol%) with the constant amount of the other additives (calculated to P 2 O 5 , K 2 O, Al 2 O 3 ) on the optical properties and photostability of doped rutile has been investigated. The properties of the obtained TiO 2 -PKAlSb samples were compared to the commercial TiO 2 -PKAl composition. The starting material was the concentrated suspension of technical-grade hydrated titanium dioxide (HTD). The dopant agents' solutions were introduced to HTD. Prepared samples were calcined with gradually increasing process temperature. The XRD analysis was used to determine the rutile content in the TiO 2 samples. Optical properties of modified titanium dioxide have been determined spectrophotometrically by measuring the colour in the white (brightness, white tone) and grey system (relative lightening power, grey tone). Photostability was characterized by the white lead-glycerin test with UV-Vis light. It was observed that with the increasing content of antimony in rutile TiO 2 , doped with phosphates, potassium and aluminium, the brightness and grey tone were increasing but white tone decreased. The changes of the relative lightening power values were insignificant. Comparing the samples of TiO 2 -PKAlSb with the TiO 2 -PKAl composition it was observed that titanium dioxide doped with antimony had better white and grey tone. The increasing Sb 2 O 3 content in the TiO 2 caused the improvement of the photostability.

  15. Spectroscopic studies of lutetium pyro-silicates Lu2Si2O7 doped with bismuth and europium

    International Nuclear Information System (INIS)

    Bretheau-Raynal, Francoise

    1981-01-01

    Single crystals of thortveitite structure pyro-silicates were grown by a floating zone technique associated with an arc image furnace. The samples were systematically characterized by X-Ray diffraction and microprobe analysis. Thanks to oriented single crystals of Lu 2 Si 2 O 7 , Yb 2 Si 2 O 7 and Sc 2 Si 2 O 7 , the recorded infrared and Raman spectra allow complete attribution of internal and external vibration modes, in good agreement with group theory predictions for C 2h factor group. Spectroscopic studies of Eu 3+ doping ion in Lu 2 Si 2 O 7 confirm C 2 point symmetry for the cationic site. Oscillator strengths and Judd-Ofelt parameters for Eu 3+ were calculated. A three level scheme ( 1 S 0 , 3 P 0 , 3 P 1 ) of Bi 3+ ion is used to explain radiative and non radiative mechanisms in Lu 2 Si 2 O 7 doped with bismuth. Finally, the mechanisms of low temperature (T =9 K) energy transfer between Bi 3+ and Eu 3+ in lutetium pyro-silicate was studied. The transfer occurs by non radiative process, without any diffusion of the excitation energy within the donor system and is due to dipole-dipole interactions between Bi 3+ and Eu 3+ ions. (author) [fr

  16. Rare Earth Free Zn3V2O8 Phosphor with Controlled Microstructure and Its Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Hom Nath Luitel

    2013-01-01

    Full Text Available Microsphere of rare earth free phosphor, Zn3V2O8, with broadband yellowish white emission was synthesized by combustion route and compared with the hydrothermal, sol-gel, and solid state reaction methods. The phosphor samples were characterized by X-ray diffraction and scanning electron microscopy. UV-visible absorption and photoluminescence (PL emission and excitation spectra were investigated for these phosphors. Zn3V2O8 phosphor containing 10 mol% of H3BO3 flux exhibited enhanced PL emission showing broadband from 450 nm to 750 nm. Effect of stoichiometry of Zn and V on the host lattice and its effect on the PL emission spectra were studied. Series of Mg3V2O8, Ca3V2O8, and Sr3V2O8 phosphors were also synthesized and compared to the Zn3V2O8 phosphor in terms of PL emission and internal quantum yield, and it was found that Zn3V2O8 is the most efficient phosphor among the other phosphors studied with quantum yield of 60%. The visible light irradiated photocatalytic activity of these phosphors was investigated and it was found that the hydrothermal Zn3V2O8 exhibited enhanced activity.

  17. Turn-on fluorescent sensor for Zinc and Cadmium ions based on quinolone and its sequential response to phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaoyan; Wang, Peng; Fu, Jiaxin; Yao, Kun; Xue, Kun [Engineering Laboratory for Flame Retardant and Functional Materials of Hennan Province, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Xu, Kuoxi, E-mail: xukx@henu.edu.cn [Engineering Laboratory for Flame Retardant and Functional Materials of Hennan Province, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China)

    2017-06-15

    Sequential fluorescence sensing of Zn{sup 2+}/Cd{sup 2+} ions and phosphate anion by new quinoline based sensors(L1 and L2) have been presented. Sensors exhibit highly selective fluorescence “turn-on” sensing properties to Zn{sup 2+}/Cd{sup 2+} ions in CH{sub 3}OH/H{sub 2}O(1/1, v/v, Tris, 10 mol·L{sup −1}, pH 7.4) solution with a 1:1 binding stoichiometry. The complexes display high selectivity to H{sub 2}PO{sub 4}{sup -} and HPO{sub 4}{sup 2-} anions through fluorescence “turn-off” respond. The results of Zn{sup 2+}/Cd{sup 2+} ions and phosphate anion sequential recognition via fluorescence changes make sensors L1 and L2 have potential utility for Zn{sup 2+}/ Cd{sup 2+} ions and phosphate anion detection in aqueous media. - Graphical abstract: Sequential fluorescence sensing of Zn{sup 2+}/Cd{sup 2+} ions and phosphate anion by new quinoline based sensors (L1 and L2) have been presented. Sensors exhibit highly selective and sensitive fluorescence “turn-on” sensing properties to Zn{sup 2+}/Cd{sup 2+} ions in CH{sub 3}OH/H{sub 2}O(1/1, v/v, Tris, 10 mM, pH 7.4) solution with a 1:1 binding stoichiometry. The complexes display high selectivity to H{sub 2}PO{sub 4}{sup -} and HPO{sub 4}{sup 2-} anions through fluorescence “turn-off” respond. Zn{sup 2+}/Cd{sup 2+} ions and phosphate anion sequential recognition via fluorescence changes make sensors L1 and L2 have potential utility for Zn{sup 2+}/ Cd{sup 2+} ions and phosphate anion detection in aqueous media.

  18. Pair Distribution Function Analysis of ZrO2 Nanocrystals and Insights in the Formation of ZrO2-YBa2Cu3O7 Nanocomposites

    Directory of Open Access Journals (Sweden)

    Hannes Rijckaert

    2018-06-01

    Full Text Available The formation of superconducting nanocomposites from preformed nanocrystals is still not well understood. Here, we examine the case of ZrO2 nanocrystals in a YBa2Cu3O7−x matrix. First we analyzed the preformed ZrO2 nanocrystals via atomic pair distribution function analysis and found that the nanocrystals have a distorted tetragonal crystal structure. Second, we investigated the influence of various surface ligands attached to the ZrO2 nanocrystals on the distribution of metal ions in the pyrolyzed matrix via secondary ion mass spectroscopy technique. The choice of stabilizing ligand is crucial in order to obtain good superconducting nanocomposite films with vortex pinning. Short, carboxylate based ligands lead to poor superconducting properties due to the inhomogeneity of metal content in the pyrolyzed matrix. Counter-intuitively, a phosphonate ligand with long chains does not disturb the growth of YBa2Cu3O7−x. Even more surprisingly, bisphosphonate polymeric ligands provide good colloidal stability in solution but do not prevent coagulation in the final film, resulting in poor pinning. These results thus shed light on the various stages of the superconducting nanocomposite formation.

  19. Fuel densification study about uranium- 7% nanostructured gadolinium (Gd2O3)

    International Nuclear Information System (INIS)

    Serafim, Antonio da Costa

    2016-01-01

    The sintering process of UO 2 -Gd 2 O 3 pellets has been investigated in this work for its importance in the nuclear industry and for its complex behavior during sintering. Sintering blockage occurs from 1300 deg C upwards, when densification is shifted toward higher temperatures and the final density obtained is decreased. This research includes the development of nuclear fuel for power reactors in order to increase its efficiency inside the reactor core by raising the burnup. The use of nanosized Gd 2 O 3 was studied in the range from 10 to 30nm, which was added to UO 2 , trying to verify the occurrence of characteristic sintering blockage due to Kirkendall sintering effect observed in previous research. The samples were produced by dry mechanical mixture of UO 2 powder and 7% Gd 2 O 3 (macro- and nanostructured). The powders were compacted and the pellets were sintered at 1700 deg C under H 2 atmosphere. These results indicate that the characteristic blockage during sintering in macrostructured system UO 2 -Gd 2 O 3 occurred in the temperature range of 1300-1500 deg C, which slows down the densification. It was observed a less intense effect when using the nanostructured Gd 2 O 3 ; it took place at the temperature of 900 deg C, then facilitating to get an additional densification. The dilatometric tests indicated shrinkage of 22, 18 and 20% respectively in UO 2 pellets, macrostructured UO 2 -7% Gd 2 O 3 and nanostructured UO 2 -7%Gd 2 O 3 . We detected 2% higher shrinkage, when nanostructured Gd 2 O 3 was used instead of macrostructured Gd 2 O 3 , which is used commercially. Then, the nanostructured results showed more adequate density for nuclear fuel usage. (author)

  20. Interdiffusion studies on high-Tc superconducting YBa2Cu3O7-δ thin films on Si(111) with a NiSi2/ZrO2 buffer layer

    DEFF Research Database (Denmark)

    Aarnink, W.A.M.; Blank, D.H.A.; Adelerhof, D.J.

    1991-01-01

    Interdiffusion studies on high-T(c) superconducting YBa2Cu3O7-delta thin films with thickness in the range of 2000-3000 angstrom, on a Si(111) substrate with a buffer layer have been performed. The buffer layer consists of a 400 angstrom thick epitaxial NiSi2 layer covered with 1200 angstrom...... of polycrystalline ZrO2. YBa2Cu3O7-delta films were prepared using laser ablation. The YBa2Cu3O7-delta films on the Si/NiSi2/ZrO2 substrates are of good quality; their critical temperatures T(c,zero) and T(c,onset) have typical values of 85 and 89 K, respectively. The critical current density j(c) at 77 K equaled 4...... x 10(4) A/cm2. With X-ray analysis (XRD), only c-axis orientation has been observed. The interdiffusion studies, using Rutherford backscattering spectrometry (RBS) and scanning Auger microscopy (SAM) show that the ZrO2 buffer layer prevents severe Si diffusion to the YBa2Cu3O7-delta layer, the Si...