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Sample records for ca sc ti

  1. No-Core Shell Model for 48-Ca, 48-Sc and 48-Ti

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, S; Stoica, S; Vary, J P; Navratil, P

    2004-10-26

    The authors report the first no-core shell model results for {sup 48}Ca, {sup 48}Sc and {sup 48}Ti with derived and modified two-body Hamiltonians. We use an oscillator basis with a limited {bar h}{Omega} range around 40/A{sup 1/3} = 11 MeV and a limited model space up to 1 {bar h}{Omega}. No single-particle energies are used. They find that the charge dependence of the bulk binding energy of eight A = 48 nuclei is reasonably described with an effective Hamiltonian derived from the CD-Bonn interaction while there is an overall underbinding by about 0.4 MeV/nucleon. However, resulting spectra exhibit deficiencies that are anticipated due to: (1) basis space limitations and/or the absence of effective many-body interactions; and, (2) the absence of genuine three-nucleon interactions. They introduce phenomenological modifications to obtain fits to total binding and low-lying spectra. The resulting no-core shell model opens a path for applications to experiments such as the double-beta ({beta}{beta}) decay process.

  2. Photoionization study of Ne-like K9+, Ca10+, Sc11+, Ti12+, V13+, Cr14+, Mn15+, and Fe16+ ions using the screening constant by unit nuclear charge method

    Science.gov (United States)

    Goyal, Arun; Khatri, Indu; Sow, Malick; Sakho, Ibrahima; Aggarwal, Sunny; Singh, A. K.; Mohan, Man

    2016-08-01

    Photoionization of the 2s22p6 (1S0) ground state of the Ne-like (Z=19-29) ions is presented in this paper. Resonance energies and total natural width of the 2s2p6np 1P series of the Ne-like K9+, Ca10+, Sc11+, Ti12+, V13+, Cr14+, Mn15+, and Fe16+are reported. All the calculations are made using the Screening constant by unit nuclear charge (SCUNC) formalism. New data for Ne-like K9+, Sc11+, Ti12+, V13+, Cr14+, and Mn15+ions are tabulated. Good agreements are found with available literature data.

  3. Enrichment of Sc2O3 and TiO2 from bauxite ore residues.

    Science.gov (United States)

    Deng, Bona; Li, Guanghui; Luo, Jun; Ye, Qing; Liu, Mingxia; Peng, Zhiwei; Jiang, Tao

    2017-06-05

    As a major byproduct generated in the alumina industry, bauxite ore residue is an important reserve of scandium and titanium. In this study, the feasibility and mechanism of enriching Sc2O3 and TiO2 from a non-magnetic material, which was obtained from carbothermal reductive roasting and magnetic separation of bauxite ore residue, were investigated based on a two-step (acidic and alkali) leaching process. It was revealed that approximately 78% SiO2 and 30-40% of CaO, FeO and Al2O3 were removed from a non-magnetic material with 0.0134wt.% Sc2O3 and 7.64wt.% TiO2 by phosphoric acidic leaching, while about 95% Al2O3 and P2O5 were further leached by subsequent sodium hydroxide leaching of the upper-stream leach residue. A Sc2O3-, TiO2- rich material containing 0.044wt.% Sc2O3 and 25.5wt.% TiO2 was obtained, the recovery and the enrichment factor of Sc2O3 and TiO2 were about 85% and 5, respectively. The enrichment of Sc2O3 was attributed to higher pH (>3.3) of phosphoric acid solution than its dissolution pH(0), and the enrichment of TiO2 was mainly associated with the insoluble perovskite (CaTiO3) in the acidic solution at ambient temperature. As Sc2O3 and TiO2 cannot be dissolved in the alkali solution, they were further enriched in the leach residue.

  4. Structural, elastic and thermodynamic properties of Ti2SC

    Indian Academy of Sciences (India)

    Hongzhi Fu; Wenfang Liu; Tao Gao

    2011-12-01

    The structural parameters, elastic constants and thermodynamic properties of Ti2SC were investigated under pressure and temperature by using first-principles plane-wave pseudopotential density functional theory within the generalized gradient approximation. The obtained results are in agreement with the available experimental data. The bulk moduli along the - and -axes, $B_{a}$ and $B_{c}$, almost linearly increase with pressure, and the former is always smaller than the latter. The ratio of $B_{c}/B_{a}$ has a trend of gradual increase as the pressure increases. It is found that the elastic constants, anisotropy and Debye temperature of Ti2SC increase with pressure, while axial compressibility along the - and -axes decreases with pressure. The thermal properties including the equation of state, the Grüneisen parameter , the anisotropies $\\Delta_{p}, \\Delta_{S1}$ and $\\Delta_{S2}$, and the heat capacity are estimated at various pressures and temperatures.

  5. Synthesis and Isolation of the Titanium-Scandium Endohedral Fullerenes-Sc2 TiC@Ih -C80 , Sc2 TiC@D5h -C80 and Sc2 TiC2 @Ih -C80 : Metal Size Tuning of the Ti(IV) /Ti(III) Redox Potentials.

    Science.gov (United States)

    Junghans, Katrin; Ghiassi, Kamran B; Samoylova, Nataliya A; Deng, Qingming; Rosenkranz, Marco; Olmstead, Marilyn M; Balch, Alan L; Popov, Alexey A

    2016-09-05

    The formation of endohedral metallofullerenes (EMFs) in an electric arc is reported for the mixed-metal Sc-Ti system utilizing methane as a reactive gas. Comparison of these results with those from the Sc/CH4 and Ti/CH4 systems as well as syntheses without methane revealed a strong mutual influence of all key components on the product distribution. Whereas a methane atmosphere alone suppresses the formation of empty cage fullerenes, the Ti/CH4 system forms mainly empty cage fullerenes. In contrast, the main fullerene products in the Sc/CH4 system are Sc4 C2 @C80 (the most abundant EMF from this synthesis), Sc3 C2 @C80 , isomers of Sc2 C2 @C82 , and the family Sc2 C2 n (2 n=74, 76, 82, 86, 90, etc.), as well as Sc3 CH@C80 . The Sc-Ti/CH4 system produces the mixed-metal Sc2 TiC@C2 n (2 n=68, 78, 80) and Sc2 TiC2 @C2 n (2 n=80) clusterfullerene families. The molecular structures of the new, transition-metal-containing endohedral fullerenes, Sc2 TiC@Ih -C80 , Sc2 TiC@D5h -C80 , and Sc2 TiC2 @Ih -C80 , were characterized by NMR spectroscopy. The structure of Sc2 TiC@Ih -C80 was also determined by single-crystal X-ray diffraction, which demonstrated the presence of a short Ti=C double bond. Both Sc2 TiC- and Sc2 TiC2 -containing clusterfullerenes have Ti-localized LUMOs. Encapsulation of the redox-active Ti ion inside the fullerene cage enables analysis of the cluster-cage strain in the endohedral fullerenes through electrochemical measurements.

  6. High-efficient physical adsorption and detection of formaldehyde using Sc- and Ti-decorated graphdiyne

    Science.gov (United States)

    Chen, Xi; Gao, Pengfei; Guo, Lei; Wen, Yanni; Fang, Dangqi; Gong, Baihua; Zhang, Yang; Zhang, Shengli

    2017-03-01

    In sensitive analysis, the ultimate limit is to achieve reliable detection on trace amount of molecules. In this work, Sc- and Ti-decorated graphdiyne were proposed as promising materials for high-efficient molecular detection. Using density functional theory calculations, we investigated the electronic response of single Sc- and Ti-atom-decorated graphdiyne to HCHO (as a typical air pollutant). Thermodynamic analysis predicted that Sc or Ti adatom could be stabilized on the corner sites of single-layer graphdiyne sheet, with migration barriers high enough to prevent Sc or Ti adatom aggregation. The adsorption of HCHO on Sc- or Ti-decorated graphdiyne was found stronger than on pristine graphene or graphdiyne, which provides a prerequisite for molecular sensing. The electronegativity of HCHO leads to strong electronic attraction from Sc or Ti adatom to HCHO, resulting in a remarkable decrease of carrier density in graphdiyne. On Ti-decorated graphdiyne, the electronic attraction of HCHO appears to be stronger than on Sc-decorated graphdiyne and changes the system from metal to n-doped semiconductor. Quantum transport calculations show a decrease of current caused by the adsorbed HCHO. The results systematically exhibit the electronic response of Sc- or Ti-decorated graphdiyne to HCHO and suggest them as promising materials for molecule detection.

  7. Magnetic properties of Sc{sub x}Ti{sub 1-x}Fe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, M. [Lab. de Cristallographie, CNRS, 38 - Grenoble (France); Deportes, J. [Lab. Louis Neel, CNRS, 38 - Grenoble (France); Ouladdiaf, B. [Institut Laue-Langevin, 38 - Grenoble (France); Sayetat, F. [Lab. de Cristallographie, CNRS, 38 - Grenoble (France)

    1995-02-09

    The magnetic properties and their thermal dependences of Sc{sub 0.1}Ti{sub 0.9}Fe{sub 1.96}, Sc{sub 0.1}Ti{sub 0.9}Fe{sub 2} and Sc{sub 0.1}Ti{sub 0.9}Fe{sub 2.04} are compared with those of TiFe{sub 2}. The substitution changes the iron-iron distances. Consequently, the Fe atoms on the 6h site show in addition to the antiferromagnetic component a small ferromagnetic one, and a weak magnetic moment appears on the 2a site. ((orig.)).

  8. Characteristics of laser clad α-Ti/TiC+(Ti,W)C1-x/Ti2SC+TiS composite coatings on TA2 titanium alloy

    Science.gov (United States)

    Zhai, Yong-Jie; Liu, Xiu-Bo; Qiao, Shi-Jie; Wang, Ming-Di; Lu, Xiao-Long; Wang, Yong-Guang; Chen, Yao; Ying, Li-Xia

    2017-03-01

    TiC reinforced Ti matrix composite coating with Ti2SC/TiS lubricant phases in-situ synthesized were prepared on TA2 titanium alloy by laser cladding with different powder mixtures: 40%Ti-19.5%TiC-40.5%WS2, 40%Ti-25.2%TiC-34.8%WS2, 40%Ti-29.4%TiC-30.6%WS2 (wt%). The phase compositions, microstructure, microhardness and tribological behaviors and wear mechanisms of coatings were investigated systematically. Results indicate that the main phase compositions of three coatings are all continuous matrix α-Ti, reinforced phases of (Ti,W)C1-x and TiC, lubricant phases of Ti2SC and TiS. The microhardness of the three different coatings are 927.1 HV0.5, 1007.5 HV0.5 and 1052.3 HV0.5, respectively. Compared with the TA2 titanium alloy (approximately 180 HV0.5), the microhardness of coatings have been improved dramatically. The coefficients of friction and the wear rates of those coatings are 0.41 and 30.98×10-5 mm3 N-1 m-1, 0.30 and 18.92×10-5 mm3 N-1 m-1, 0.34 and 15.98×10-5 mm3 N-1 m-1, respectively. Comparatively speaking, the coating fabricated with the powder mixtures of 40%Ti-25.2%TiC-34.8%WS2 presents superior friction reduction and anti-wear properties and the main wear mechanisms of that are slight plastic deformation and adhesive wear.

  9. Structural and magnetic properties of Ti12M clusters (M=Sc to Zn)

    Science.gov (United States)

    Sun, Houqian; Xu, Ning

    2016-12-01

    The geometries, electronic, and magnetic properties of the 3d atom doped icosahedron (ICO) Ti12M (M=Sc to Zn), where a dopant atom replaces either the centra l(Ti12Mc) or surface (Ti12Ms) Ti atom in ICO Ti13 cluster, have been systematically investigated by using the density functional theory. The structures of all the optimized Ti12Mc and Ti12Ms clusters are distorted ICO. Sc, Ni, Cu, and Zn atoms prefer to displace surface Ti atom, V, Cr, Mn, and Fe atoms prefer to displace central Ti atom. The position of impurity atom depends on the strength of the interaction between the central atom and the surface atoms. As compared to the pure Ti13 cluster, Ti12Mc and Ti12Ms (M=V, Fe, Co, and Ni) clusters are more stable, Ti12Mc and Ti12Ms (M=Sc, Cr, Mn, Cu, and Zn) are less stable. Both Ti12Nis and Ti12Nic are magic clusters, which originate from their electronic as well as geometric closed shells. Because the exchange interaction prevails over the crystal field in Ti12M clusters, the valence electrons fill molecular orbitals in terms of Hund's rule of maximum spin.

  10. Valence electron structure analysis of refining mecha-nism of Sc and Ti additions on aluminum

    Institute of Scientific and Technical Information of China (English)

    LI PieJie; YE YiCong; HE LiangJu

    2009-01-01

    The mechanism of the difference of refining effect between Sc and Ti adding to aluminum can not be explained substantially with traditional theory. Valence electron structures of AI-Ti and Al-Sc alloys have been studied by using the empirical electron theory of solids and molecules (EET). The covalent bond electron numbers and interfacial electron density differences are calculated. The conclusion is that, in the two alloys, different covalent bond electron numbers of nucleation particles, and different electron densities on the interface between the second phase particles and the matrix, fundamentally lead to the difference of refining effect between Sc and Ti adding to aluminum.

  11. Precise Determination of 40Ti Mass by Measuring the 40Sc Isospin Analogue State

    Institute of Scientific and Technical Information of China (English)

    LIU Wei-Ping(柳卫平); E. Roeckl; M. Pfützner; L. Chulkov; A. Piechaczek; R. Raabe; I. Reusen; G. Vancraeynest; A. Wohr; M. Hellstrom2; R. Collatz; J. Benlliure; D. Cortina Gil; F. Farget; H. Grawe; Z. Hu; N. Iwasa

    2001-01-01

    The mass of 40 Ti has been determined by using the isobaric multiplet mass equation method. The experimental data of the 40Tiβ-decay were used to determine the level of the isospin analogue state of 40Sc. The ground-state mass excess and the QEc value for 40 Ti were determined to be -9060 ± 12 keV and 11 466 ± 13keV, respectively.

  12. Naked (C5Me5)(2)M cations (M = Sc, Ti, and V) and their fluoroarene complexes

    NARCIS (Netherlands)

    Bouwkamp, MW; Budzelaar, PHM; Gercama, J; Morales, ID; de Wolf, J; Meetsma, A; Troyanov, SI; Teuben, JH; Hessen, B; Budzelaar, Peter H.M.; Hierro Morales, Isabel Del; Troyanov, Sergei I.

    2005-01-01

    The ionic metallocene complexes [Cp*M-2][BPh4] (CP* = C5Me5) of the trivalent 3d metals Sc, Ti, and V were synthesized and structurally characterized. For M Sc, the anion interacts weakly with the metal center through one of the phenyl groups, but for M = Ti and V, the cations are naked. They each c

  13. Effect of Severe Plastic Deformation on Structure and Properties of Al-Sc-Ta and Al-Sc-Ti Alloys.

    Science.gov (United States)

    Berezina, Alla; Monastyrska, Tetiana; Davydenko, Olexandr; Molebny, Oleh; Polishchuk, Sergey

    2017-12-01

    The comparative analysis of the effect of monotonous and non-monotonous severe plastic deformations (SPD) on the structure and properties of aluminum alloys has been carried out. Conventional hydrostatic extrusion (HE) with a constant deformation direction and equal-channel angular hydroextrusion (ECAH) with an abrupt change in the deformation direction were chosen for the cases of monotonous and non-monotonous SPD, respectively. Model cast hypoeutectic Al-0.3%Sc alloys and hypereutectic Al-0.6%Sc alloys with Ta and Ti additives were chosen for studying. It was demonstrated that SPD of the alloys resulted in the segregation of the material into active and inactive zones which formed a banded structure. The active zones were shown to be bands of localized plastic deformation. The distance between zones was found to be independent of the accumulated strain degree and was in the range of 0.6-1 μm. Dynamic recrystallization in the active zones was observed using TEM. The dynamic recrystallization was accompanied by the formation of disclinations, deformation bands, low-angle, and high-angle boundaries, i.e., rotational deformation modes developed. The dynamic recrystallization was more intense during the non-monotonous deformation as compared with the monotonous one, which was confirmed by the reduction of texture degree in the materials after ECAH.

  14. Influence of Sc on high temperature strengthening behavior of Ti-6Al-4V alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Vacuum arc melting technique was used to prepare Ti-6Al-4V alloy containing Sc (0.3% and 0.5%, mass fraction). The ingots were melted twice by vacuum self-consumable electrode arc furnace. Forging of ingots was started in β-phase region and finished in high (α+β)-phase region. Annealing after forging was performed in low (α+β)-phase region for 30 min. Isothermal high temperature compression tests were conducted using thermal simulation machine under Ar atmosphere at 850 ℃ and 1 000 ℃, and the strain rate were 0.001, 0.01, 0.1 and 1.0 s-1. Optical microscope(OM), scanning electron microscopy(SEM), energy dispersive spectrum(EDS) and transmission electron microscope(TEM) were used to study the microstructure evolution during high temperature deformation. The results show that, the peak stress value of alloys increases with increasing Sc content after deformation at 850 ℃,however, there is no obvious strengthening of Sc when the alloys are deformed at 1 000 ℃. Sc exists as Sc2O3 forms by internal oxidation during forging procedure, only minor Sc solutes in matrix. At 850 ℃, the interaction between dislocation and participated particles and twinning mechanism controls the deformation procedure accompanied recrystallization. At 1 000 ℃, the deformation of alloys containing Sc is mainly controlled by twinning, while the deformation of alloy without Sc is not only controlled by twinning,but also the interaction between dislocation and precipitated particles inside the twinning lamellar.

  15. Experimental Investigation of Electrical Conductivity and Permittivity of SC-TiO 2 -EG Nanofluids

    Science.gov (United States)

    Fal, Jacek; Barylyak, Adriana; Besaha, Khrystyna; Bobitski, Yaroslav V.; Cholewa, Marian; Zawlik, Izabela; Szmuc, Kamil; Cebulski, Józef; żyła, Gaweł

    2016-08-01

    The paper presents experimental studies of dielectric properties of nanofluids based on ethylene glycol and SC-TiO2 nanoparticles with average size of 15-40 nm with various mass concentrations. The dielectric permittivity both real part and imaginary part as a function of temperature and frequency were measured. Also, dependence ac conductivity on frequency, temperature, and mass concentration were investigated. Based on the curves of ac conductivity, dc conductivity was calculated, and 400 % enhancement in dc conductivity was exposed.

  16. Experimental Investigation of Electrical Conductivity and Permittivity of SC-TiO 2 -EG Nanofluids.

    Science.gov (United States)

    Fal, Jacek; Barylyak, Adriana; Besaha, Khrystyna; Bobitski, Yaroslav V; Cholewa, Marian; Zawlik, Izabela; Szmuc, Kamil; Cebulski, Józef; Żyła, Gaweł

    2016-12-01

    The paper presents experimental studies of dielectric properties of nanofluids based on ethylene glycol and SC-TiO2 nanoparticles with average size of 15-40 nm with various mass concentrations. The dielectric permittivity both real part and imaginary part as a function of temperature and frequency were measured. Also, dependence ac conductivity on frequency, temperature, and mass concentration were investigated. Based on the curves of ac conductivity, dc conductivity was calculated, and 400 % enhancement in dc conductivity was exposed.

  17. Strength of the $E_{\\text{p}}$=1.842 MeV resonance in the $^{40}$Ca(p,$\\gamma$)$^{41}$Sc reaction revisited

    CERN Document Server

    Schmidt, Konrad; Anders, Michael; Bemmerer, Daniel; Caciolli, Antonio; Dietz, Mirco; Elekes, Zoltán; Junghans, Arnd R; Menzel, Marie-Luise; Schwengner, Ronald; Wagner, Andreas; Zuber, Kai

    2014-01-01

    The strength of the $E_{\\rm p} = 1.842$ MeV resonance in the $^{40}$Ca(p,$\\gamma$)$^{41}$Sc reaction is determined with two different methods: First, by an absolute strength measurement using calcium hydroxide targets, and second, relative to the well-determined strength of the resonance triplet at $E_\\alpha$ = 4.5 MeV in the $^{40}$Ca($\\alpha$,$\\gamma$)$^{44}$Ti reaction. The present new value of $\\omega\\gamma=(0.192\\pm0.017)$ eV is 37% (equivalent to $3.5\\sigma$) higher than the evaluated literature value. In addition, the ratio of the strengths of the 1.842 MeV $^{40}$Ca(p,$\\gamma$)$^{41}$Sc and 4.5 MeV $^{40}$Ca($\\alpha$,$\\gamma$)$^{44}$Ti resonances has been determined to be $0.0229\\pm0.0018$. The newly corrected strength of the 1.842-MeV resonance can be used in the future as a normalization point for experiments with calcium targets.

  18. Local character of the highest antiferromagnetic Ce-system CeTi{1-x}Sc{x} Ge

    OpenAIRE

    2014-01-01

    The highest antiferromagnetic (AFM) temperature in Ce based compounds has been reported for CeScGe with Tn=47K, but its local or itinerant nature was not deeply investigated yet. In order to shed more light into this unusually high ordering temperature we have investigated structural, magnetic, transport and thermal properties of CeTi{1-x}Sc{x}Ge alloys within the range of stability of the CeScSi-type structure: 0.25

  19. The [Fe/H] Dependence on the Ca {\\sc ii}-$M_V$ Relationship

    CERN Document Server

    Gomez, Thomas; Pancino, Elena

    2012-01-01

    We examined the Wilson-Bappu effect, a relationship between the absolute magnitude of the star, $M_V$, and the logarithm of the Ca {\\sc ii} emission width, $W_0$, over the largest $M_V$ range to date, +13 to -5, covering M-dwarfs to type Ia supergiants. We used an extensive literature, the latest Hipparcos reduction, data from two globular clusters, and new observations from Apache Point Observatory to compile a sample that allowed us to study the effect of [Fe/H] on the Wilson-Bappu relationship. Our results include reporting the deviations from linearity and demonstrating that the Wilson-Bappu relationship is insensitive to metallicity.

  20. Doping of BiScO3-PbTiO3 Ceramics for Enhanced Properties

    Science.gov (United States)

    Sehirlioglu, Alp; Sayir, Ali; Dynys, Fred

    2008-01-01

    High-temperature piezoelectrics are a key technology for aeronautics and aerospace applications such as fuel modulation to increase the engine efficiency and decrease emissions. The principal challenge for the insertion of piezoelectric materials is the limitation on upper use temperature which is due to low Curie-Temperature (T(sub c) and increasing electrical conductivity. BiScO3 -PbTiO3 (BS-PT) system is a promising candidate for improving the operating temperature for piezoelectric actuators due to its high TC (>400 C). Effects of Zr and Mn doping of the BS-PT ceramics have been studied and all electrical and electromechanical properties for Sc-deficient and Ti-deficient BS- PT ceramics are reported as a function of electrical field and temperature. Donor doping with Zr and Mn (in Sc deficient compositions) increased the DC-resistivity and decreased tan at all temperatures. Resulting ceramics exhibited saturated hysteresis loops with low losses and showed no dependence on the applied field (above twice the coercive field) and measurement frequency.

  1. Piezoelectric and Dielectric Properties of Multilayered BaTiO3/(Ba,Ca)TiO3/CaTiO3 Thin Films.

    Science.gov (United States)

    Zhu, Xiao Na; Gao, Ting Ting; Xu, Xing; Liang, Wei Zheng; Lin, Yuan; Chen, Chonglin; Chen, Xiang Ming

    2016-08-31

    Highly oriented multilayered BaTiO3-(Ba,Ca)TiO3-CaTiO3 thin films were fabricated on Nb-doped (001) SrTiO3 (Nb:STO) substrates by pulsed laser deposition. The configurations of multilayered BaTiO3-(Ba,Ca)TiO3-CaTiO3 thin films are designed with the thickness ratio of 1:1:1 and 2:1:1 and total thickness ∼300 nm. Microstructural characterization by X-ray diffraction indicates that the as-deposited thin films are highly c-axis oriented and large in-plane strain is determined in BaTiO3 and CaTiO3 layers. Piezoresponse force microscopy (PFM) studies reveal an intense in-plane polarization component, whereas the out-of-plane shows inferior phase contrast. The optimized combination is found to be the BaTiO3-(Ba0.85Ca0.15)TiO3-CaTiO3 structure with combination ratio 2:1:1, which displays the largest domain switching amplitude under DC electric field, the largest room-temperature dielectric constant ∼646, a small dielectric loss of 0.03, and the largest dielectric tunability of ∼50% at 400 kV/cm. These results suggest that the enhanced dielectric and tunability performance are greatly associated with the large in-plane polarization component and domain switching.

  2. Influence of Sc3+ doping in B-site on electrochemical performance of Li4Ti5O12 anode materials for lithium-ion battery

    Science.gov (United States)

    Zhang, Yaoyao; Zhang, Chunming; Lin, Ye; Xiong, Ding-Bang; Wang, Dan; Wu, Xiaoyan; He, Dannong

    2014-03-01

    Anode materials Li4Ti5O12 (LTO) and Sc-doped Li4Ti4.95Sc0.05O12-δ (LTSO) for lithium-ion batteries are both successfully synthesized by the modified sol-gel method with ethylene diamine tetraacetic acid (EDTA) and citric acid (CA) as a bi-components chelating agent. The samples are characterized by XRD, BET, XPS, EDX and SEM. The dopant Sc totally enters into the 16d sites of the spinel structure of LTO, and then further affects its morphology and property. The LTSO powder exhibits a 3D network morphology and its grain size is about 200 nm. The LTSO electrode material exhibits an excellent initial discharge capacities of 174 and 94 mAh g-1 at 1 C and 40 C, respectively. The reversible capacities of LTSO at different current rates remain nearly 100% after 50 cycles, which are compared with the capacities of the second cycles. Sc3+ doping can greatly improve the electronic conductivity of LTO which is demonstrated by electrochemical impedance spectroscopy. Cyclic voltammetry measurements also reveal that LTSO has small polarization resistance due to the high electrical conductivity and Li-ion apparent diffusion rate.

  3. Ca- and Sc-based ternary AlB2-like crystals: a first-principles study

    Science.gov (United States)

    Tsetseris, Leonidas

    2017-02-01

    The aluminum diboride (AlB2) crystal structure comprises intercalated metal atoms between honeycomb sheets. In addition to metal diborides, which represent the most common family of AlB2-like structures, many more materials are known to crystallize in this geometry. Here we use first-principles calculations to probe the structural and electronic properties of several such systems. Specifically, we investigate the stability of various polymorphs of CaAuAs, CaAuP, CaCuP, ScAuGe, ScAuSi, Ca2AgSi3 and Ca2AuGe3 and find lattice parameters in excellent agreement with available experimental data. The analysis of densities of states and band structure diagrams show that all materials are metallic. However, the details of band dispersion vary significantly, from typical metals such as CaAuP, to almost semi-metallic behaviour in CaCuP.

  4. The luminescence of titanite (CaTiSiO5)

    NARCIS (Netherlands)

    Blasse, G.; Dirksen, G.J.; Tanaka, I.; Kojima, H.

    1988-01-01

    The luminescence of CaTiSiO5 crystals is reported. The emission band has its maximum at 520 nm. The results are discussed in connection with titanium compounds containing comparable titanate polyhedra.

  5. Systematics in back-angle alpha-particle scattering: Sc, Ti, V, and Cr isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Eberhard, K.A.; Wit, M.; Schiele, J.; Trombik, W.; Zipper, W.; Schiffer, J.P.

    1976-12-01

    Elastic ..cap alpha..-scattering cross sections from /sup 45/Sc, /sup 49/,/sup 50/Ti, /sup 50/,/sup 52/,/sup 53/Cr and /sup 50/,/sup 51/V have been measured between 140degree and 180degree at a bombarding energy of E/sub b/(lab) = 25 MeV. All angular distributions are similar and show no evidence of an anomalous backward enhancement. No evidence for a spin dependence of the cross section within experimental uncertainties, is found for these nuclei, where the spins range from I = 0 (/sup 50/Ti, /sup 50/Cr) to I = 6 (/sup 50/V). Back-angle integrated cross sections (140degree--180degree) are compared with neighbor target nuclei between A approx. = 40 and A approx. = 60. (AIP)

  6. Relative x-ray backlighter intensity comparison of ti and ti/sc combination foils driven in double-sided and single-sided laser configuration

    Energy Technology Data Exchange (ETDEWEB)

    Bullock, A B; Landen, O L; Bradley, D K

    2000-06-05

    Use of multiple backlighter foils and/or double-sided laser interaction geometry with backlit imaging can result in improved backlighter efficiency. An experimental comparison of backlighter intensity for Ti foils and Ti/Sc combination foils in both the one-sided and double-sided laser-interaction configuration is presented. Spectrally-integrated framing camera images show intensity contributions of front and rear backlighter surfaces for both foil types. Analysis of time-resolved x-ray spectra collected from foil targets show the relative contribution of Ti and Sc 2-1 He-like resonance lines to the total backlighter intensity.

  7. Development of single chain variable fragment (scFv) antibodies against surface proteins of 'Ca. Liberibacter asiaticus'.

    Science.gov (United States)

    Yuan, Qing; Jordan, Ramon; Brlansky, Ronald H; Minenkova, Olga; Hartung, John

    2016-03-01

    'Candidatus Liberibacter asiaticus' is the causal agent of citrus huanglongbing, the most serious disease of citrus worldwide. We have developed and applied immunization and affinity screening methods to develop a primary library of recombinant single chain variable fragment (scFv) antibodies in an M13 vector, pKM19. The antibody population is enriched for antibodies that bind antigens of 'Ca. Liberibacter asiaticus'. The primary library has more than 10(7) unique antibodies and the genes that encode them. We have screened this library for antibodies that bind to specifically-chosen proteins that are present on the surface of 'Ca. Liberibacter asiaticus'. These proteins were used as targets for affinity-based selection of scFvs that bind to the major outer membrane protein, OmpA; the polysaccharide capsule protein KpsF; a protein component of the type IV pilus (CapF); and, two flagellar proteins FlhA and FlgI. These scFvs have been used in ELISA and dot blot assays against purified protein antigens and 'Ca. Liberibacter asiaticus' infected plant extracts. We have also recloned many of these scFvs into a plasmid expression vector designed for the production of scFvs. Screening of these scFvs was more efficient when phage-bound, rather than soluble scFvs, were used. We have demonstrated a technology to produce antibodies at will and against any protein target encoded by 'Ca. Liberibacter asiaticus'. Applications could include advanced diagnostic methods for huanglongbing and the development of immune labeling reagents for in planta applications.

  8. Thermoelastic properties of ScB2, TiB2, YB4 and HoB4

    DEFF Research Database (Denmark)

    Waskowska, A.; Gerward, L.; Staun Olsen, J.

    2011-01-01

    High-pressure X-ray diffraction in ScB2, TiB2, YB4 and HoB4 powders and single crystals has been studied using synchrotron radiation as well as conventional X-rays. The experimental results are supported by calculations using density functional theory. ScB2, YB4 and HoB4 are hard materials (bulk...... modulus 180-200GPa), while TiB2 may be classified as superhard (bulk modulus about 260GPa). We report here first experimental and theoretical determinations of the bulk modulus for HoB4 (195(5) and 198.2GPa, respectively), and first experimental values of the bulk modulus for ScB2 (196(2)GPa) and YB4 (185...

  9. Origin of colossal dielectric response of CaCu3Ti4O12 studied by using CaTiO3/CaCu3Ti4O12/CaTiO3 multilayer thin films

    Science.gov (United States)

    Mitsugi, Masakazu; Asanuma, Shutaro; Uesu, Yoshiaki; Fukunaga, Mamoru; Kobayashi, Wataru; Terasaki, Ichiro

    2007-06-01

    To elucidate the origin of the colossal dielectric response (CDR) of CaCu3Ti4O12 (CCTO), multilayer thin films of CCTO interposed in insulating CaTiO3 (CTO) were synthesized using a pulsed laser deposition technique. The capacitance C of CTO/CCTO/CTO films with different layer thicknesses is measured. After removing the capacitance of CTO by extrapolating C to zero CTO thickness, the real part of dielectric constant of CCTO is estimated to be 329-435, which is much smaller than the reported value for CCTO thin films. This fact indicates that the CDR of CCTO is extrinsic and originates from an internal barrier layer capacitor.

  10. Interaction in (Ti,Sc)Fe{sub 2}-H{sub 2} and (Zr,Sc)Fe{sub 2}-H{sub 2} systems

    Energy Technology Data Exchange (ETDEWEB)

    Zotov, T.; Movlaev, E. [Chemistry Department, Lomonosov Moscow State University, Lenin Hill, 119992 Moscow (Russian Federation); Mitrokhin, S. [Chemistry Department, Lomonosov Moscow State University, Lenin Hill, 119992 Moscow (Russian Federation)], E-mail: Mitrokhin@hydride.chem.msu.ru; Verbetsky, V. [Chemistry Department, Lomonosov Moscow State University, Lenin Hill, 119992 Moscow (Russian Federation)

    2008-07-14

    Results of investigation of hydrogen sorption properties of Ti(Zr){sub x}Sc{sub 1-x}Fe{sub 2} (x = 1, 0.8 and 0.5) alloys are presented. The measurements were performed for pressures up to 3000 atm. In case of titanium alloys hydride formation was established only for x = 0.5. Estimated equilibrium absorption pressure for x = 0.8 and 1.0 was too high for experimental limits of the device. In case of zirconium alloys hydride formation was found for all three concentrations. Absorption-desorption isotherms were measured for the first time for ZrFe{sub 2}-H{sub 2} system. Calculated enthalpy of hydrogen desorption was found to be 21.3 kJ/mole H{sub 2}.

  11. In vitro bioactivity study of TiCaPCO(N) and Ag-doped TiCaPCO(N) films in simulated body fluid.

    Science.gov (United States)

    Sukhorukova, I V; Sheveyko, A N; Kiryukhantsev-Korneev, Ph V; Levashov, E A; Shtansky, D V

    2017-01-01

    Bioactivity of multicomponent TiCaPCO(N) and Ag-doped TiCaPCO(N) films was evaluated in vitro using simulated body fluid (SBF) and compared with that of bioactive glass Biogran. The first group of films was fabricated by magnetron sputtering of composite TiС0.5 -Ti3 POx -CaO target produced via the self-propagating high-temperature synthesis (SHS) method (TiCaPCON films), after which their surface was implanted with Ag(+) ions to obtain Ag-doped TiCaPCON films. The second group of films was fabricated by pulsed electrospark deposition (PED) using SHS-produced composite TiС0.5 -Ti3 POx -CaO and TiС0.5 -Ti3 POx -CaO-Ag electrodes. After immersion in SBF, the structure and chemistry of surface were well characterized using a combination of various microanalytical techniques, such as scanning electron microscopy, X-ray diffractometry (both in conventional and grazing incidence mode), Fourier transform infrared spectroscopy, Raman spectroscopy, and glow discharge optical emission spectroscopy. The results showed that the surfaces of the TiCaPCO(N) and Ag-doped TiCaPCO(N) films were bioactive in vitro and induced the formation of an apatite layer during exposure in SBF. In the case of the magnetron-sputtered films, the apatite layer was formed over 14 days, while 28 days were needed to form CaP phase on the surface of PED-modified samples. Various factors (film structure, surface roughness, surface functional groups, surface charge, and composition, supersaturation, and near-surface local supersaturation of SBF) affecting the kinetics of bone-like apatite formation on a bioactive surface are discussed. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 193-203, 2017.

  12. Spectral variations of Ca3Sc2Si3O12:Ce phosphors via substitution and energy transfer

    Institute of Scientific and Technical Information of China (English)

    LIU Yuanhong; ZHUANG Weidong; LIU Ronghui; HU Yunsheng; HE Huaqiang; ZHANG Shusheng; GAO Wei

    2012-01-01

    The luminescence intensity of emission peak at around 525 nm decreased in the Ce3+ and Er3+ co-doped Ca3Sc2Si3O12 phosphors.Mg2+ ion,which was likely incorporated into the Sc3+ position of the host crystal,was co-doped to adjust the crystal field and compensate for the excess positive charge due to the doping of Ce3+.The green emission belonged to the 5d→4f transition of Ce3+ moved toward longer wavelength by addition of Mg2+ in Ce3+ and Er3+ co-doped Ca3Sc2Si3O12 phosphor,which could increase the brightness of the phosphor.However,the position of weakening of luminescence intensity at around 525 nm remained basically unchanged by increasing the amount of Mg2+.The results showed that the weakening of luminescence intensity at around 525 nm caused by the absorption of Er3+,which had littleinfluence on the environment of the crystal field.

  13. Reactivity of first-row transition metal monocations (Sc+, Ti+, V+, Zn+) with methyl fluoride: a computational study.

    Science.gov (United States)

    Redondo, Pilar; Varela-Álvarez, Adrián; Rayón, Víctor Manuel; Largo, Antonio; Sordo, José Ángel; Barrientos, Carmen

    2013-04-11

    The gas-phase reactivity of methyl fluoride with selected first-row transition metal monocations (Sc(+), Ti(+), V(+), and Zn(+)) has been theoretically investigated. Our thermochemical and kinetics study shows that early transition-metal cations exhibit a much more active chemistry than the latest transition metal monocation Zn(+). The strong C-F bond in methyl fluorine can be activated by scandium, titanium, and vanadium monocations yielding the metal fluorine cation, MF(+). However, the rate efficiencies vary dramatically along the period 0.73 (Sc), 0.91 (Ti), and 0.028 (V) in agreement with the experimental observation. The kinetics results show the relative importance of the entrance and exit channels, apart from the "inner" bottleneck, to control the global rate constant of these reactions. At the mPW1K/QZVPP level our computed kglobal (at 295 K), 1.99 × 10(-9) cm(3) molecule(-1) s(-1) (Sc(+)), 1.29 × 10(-9) cm(3) molecule(-1) s(-1) (Ti(+)), and 3.46 × 10(-10) cm(3) molecule(-1) s(-1) (V(+)) are in good agreement with the experimental data at the same temperature. For the reaction of Zn(+) and CH3F our predicted value for kouter, at 295 K, 3.79 × 10(-9) cm(3) molecule(-1) s(-1), is in accordance with the capture rate constant. Our study suggests that consideration of the lowest excited states for Ti(+) and V(+) is mandatory to reach agreement between calculations and experimental measurements.

  14. Structural and optical properties of epitaxial BaTiO3 thin films grown on GdScO3(110).

    OpenAIRE

    Schubert, J; Trithaveesak, O.; Petraru, A.; Jia, C. L.; Uecker, R.; Reiche, P.; Schlom, D. G.

    2003-01-01

    We have prepared 1-mum-thick epitaxial BaTiO3 thin films on GdScO3(110) using pulsed laser deposition. The structural perfection of the films was revealed by a rocking curve width of Deltaomega=0.13degrees for the 002 BaTiO3 reflection and a Rutherford backscattering spectrometry/channeling minimum yield, chi(min), of 0.5% measured for the Ba signal behind the surface peak. High-resolution transmission electron microscopy revealed an epitaxial relationship between BaTiO3 and GdScO3 and a shar...

  15. Clustering of O–X, X = (Ag, Al, Ga, Sn, Sc, Zn, Zr) point defects in hexagonal Ti: Formation mechanism and ductility variations

    Energy Technology Data Exchange (ETDEWEB)

    Kwasniak, P., E-mail: piotr.kwasniak@inmat.pw.edu.pl; Muzyk, M.; Garbacz, H.; Kurzydlowski, K.J.

    2015-03-15

    The interactions of prime interstitial and alloying elements in hexagonal Ti were investigated using a density functional theory calculations. The binding energies of oxygen with all substitution elements whose solubility limit in α-Ti is greater than 3 at% were calculated. The investigations performed reveal no attraction between Zn, Zr, Ag and O, and strong O–Sc and O–Sn binding. It was found that the O–X clustering mechanism is based on a direct and long-range O–X interaction, both controlled by valence structure and electronegativity of substitational elements. The single crystal and isotropic elastic constants together with Pugh's plasticity criterion were calculated for Ti with multiple point defects to evaluate their impact on mechanical properties. The results obtained reveal that a low concentration of O improves ductility in Ti + Sc solid solutions and increases the brittleness of Ti + Sn alloys. The diverse effect on ductility is due to different chemical bond types in the vicinity of O. The results show that the interstitial-substitational elements clustering effect may be used to optimize mechanical properties of α-Ti alloys. - Highlights: • DFT calculations were performed to investigate the point defects binding in α-Ti. • Sn and Sc exhibit the highest attraction to O in α-Ti lattice. • O–X interaction is controlled by short- and long range interactions. • Oxygen can suppress or enhance ductility of α-Ti-X solid solutions.

  16. Visible luminescence of lanthanide ions in Ca3Sc2Si3O12 and Ca3Y2Si3O12

    Institute of Scientific and Technical Information of China (English)

    Fabio Piccinelli; Adolfo Speghini; Gino Mariotto; Laura Bovo; Marco Bettinelli

    2009-01-01

    The crystalline materials Ca3Sc2Si3O12 and Ca3Y2Si3O12 were characterized by different crystal structures,as the former is a cubic garnet,while the latter is an orthorhombic compound.We investigated the optical spectroscopy of these materials doped with several trivalent lanthanide ions and compared the results for the two hosts.Polycrystalline samples were prepared by solid state reaction,both undoped and doped with the trivalent lanthanide ions Eu3+,Tb3+ and Sm3+.Emission,excitation and Raman spectra of these materials were measured at temperatures ranging from 300 to 10 K.The optical spectra were assigned and discussed,and the effects of the crystal structure of the host on the spectroscopic behaviour were addressed.The technological potential of these compounds in the field of optical materials and devices was discussed.

  17. Structures and Mechanical and Electronic Properties of the Ti2CO2 MXene Incorporated with Neighboring Elements (Sc, V, B and N)

    Science.gov (United States)

    Feng, Li; Zha, Xian-Hu; Luo, Kan; Huang, Qing; He, Jian; Liu, Yijun; Deng, Wei; Du, Shiyu

    2017-04-01

    Ti2CO2, as the representative MXene with semiconducting characteristics and ultrahigh carrier mobility, has attracted increasing attention in material science. Herein, various Ti2CO2 alloys with Ti displaced by neighboring elements Sc and V, or C by B and N are investigated in this paper based on the first-principles density functional calculations. The structures and mechanical and electronic properties are thoroughly studied for the configurations with varying alloying atom concentrations. The choices of alloying elements play a critical role in determining the lattice parameters and layer thickness. The Sc substitutions generally increase the lattice parameter but decrease the layer thickness. In contrast, the introduction of N presents slight influence on the structural parameters. The mechanical strength shows remarkable variations by introducing the alloying elements. The maximum elastic constant c 11 is determined to be 425 GPa in (Ti0.25V0.75)2CO2, and the corresponding minimum value is only 104 GPa found in (Ti0.125Sc0.875)2CO2. With respect to the electronic properties, although B and Sc both present one less valance electron compared to their replaced elements C and Ti, it is easier to realize the p-type semiconductor in the configurations containing Sc. Both the V and N substitutions are capable of generating n-type semiconductors, but their optimal stoichiometric compositions are quite different. Among all the configurations investigated, only (Ti0.5V0.5)2CO2 and (Ti0.375V0.625)2CO2 are magnetic, with their magnetism determined to be 2.61 uB/cell and 1.52 uB/cell, respectively. Thus, the method of alloying neighboring elements provides an effective approach in manipulating the physical properties of the Ti2CO2, which might widen the possible applications of MXene materials.

  18. Biological properties of nanostructured Ti incorporated with Ca, P and Ag by electrochemical method

    Energy Technology Data Exchange (ETDEWEB)

    Li, Baoe; Hao, Jingzu; Min, Yang [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Xin, Shigang [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Guo, Litong [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); He, Fei [National Key Laboratory of C1 Chemical Industry, Tianjin University, Tianjin 300072 (China); Liang, Chunyong; Wang, Hongshui [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Li, Haipeng, E-mail: lhpcx@163.com [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China)

    2015-06-01

    TiO{sub 2} nanotube arrays were synthesized on Ti surface by anodic oxidation. The elements of Ca and P were simultaneously incorporated during nanotubes growth in SBF electrolyte, and then Ag was introduced to nanotube arrays by cathodic deposition, which endowed the good osseointegration and antibacterial property of Ti. The bioactivity of the Ti surface was evaluated by simulated body fluid soaking test. The biocompatibility was investigated by in vitro cell culture test. And the antibacterial effect against Staphylococcus aureus was examined by the bacterial counting method. The results showed that the incorporation of Ca, P and Ag elements had no significant influence on the formation of nanotube arrays on Ti surface during electrochemical treatment. Compared to the polished or nanotubular Ti surface, TiO{sub 2} nanotube arrays incorporated with Ca, P and Ag increased the formation of bone-like apatite in simulated body fluid, enhanced cell adhesion and proliferation, and inhibited the bacterial growth. Based on these results, it can be concluded that the nanostructured Ti incorporated with Ca, P and Ag by electrochemical method has promising applications as implant material. - Highlights: • Nanotube arrays were prepared on Ti surface by anodic oxidation. • Ca, P and Ag were incorporated to nanotube arrays by electrochemical method. • Ca, P and Ag endowed Ti with good osseointegration and antibacterial property. • The beneficial effect of electrochemical treatment on Ti implant was demonstrated.

  19. Reorientable dipolar CuCa antisite and anomalous screening in CaCu3Ti4O12

    Science.gov (United States)

    Delugas, Pietro; Alippi, Paola; Fiorentini, Vincenzo; Raineri, Vito

    2010-02-01

    Based on first-principles calculations, we show that the abundant CuCa antisite defect contributes sizably to dielectric screening in single-crystal CaCu3Ti4O12 . CuCa has a multi-minimum off-center equilibrium configuration, whereby it possesses a large and easily reorientable dipole moment. The low-temperature and frequency cut-off behavior of CuCa -induced response is consistent with experiment.

  20. Metal-insulator transitions in LaTiO3 / CaTiO3 superlattices

    Science.gov (United States)

    Seo, Sung Seok A.; Lee, Ho Nyung

    2010-03-01

    Strongly correlated electrons at an interface of complex oxide heterostructures often show interesting behaviors that require an introduction of new physical concepts. For example, the metallic transport behavior found in the superlattices of a Mott insulator LaTiO3 and a band insulator SrTiO3 (STO) has established the concept of interfacial electronic reconstruction. In this work, we have studied the transport property of a new type of Mott/band insulator LaTiO3/CaTiO3 (LTO/CTO) superlattices grown by pulsed laser deposition (PLD). In order to rule out concerns about the PLD plume-triggered oxygen vacancies generated in STO substrates, which might influence transport measurement, and to investigate the effect of epitaxial strain, we have used insulating NdGaO3 substrates. While both LTO and CTO single films are highly insulating, we have observed intriguing metal-insulator transitions (MIT) in the LTO/CTO superlattices depending on the global LTO/CTO thickness ratio and temperature. (Note that LTO/STO superlattices are metallic at all temperatures (2-300 K)). In this talk, we will discuss the origin of the MIT in the scheme of self compensation mechanism of d-electrons at the hetero-interface between LTO and CTO.

  1. Hydrogen Storage Properties of Ti1.2Fe+xCa Hydrogen Storage Alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The hydrogen storage properties of Ti1.2Fe+xCa (x=1%, 3% and 5% in mass fraction) alloys was investigated. Results show that the modified alloys can be activated without any thermal treatment at room temperature due to the addition of Ca and excess Ti in the alloys. Hydrogen storage properties of these modified alloys vary with Ca amount and reaction temperature. In addition, the influence mechanism of the addition of Ca and excessive Ti on the activation behavior and hydrogen storage capacity of the alloys was discussed.

  2. Magnetic ground state of Ti{sub 1-x}Sc{sub x}Fe{sub 2} system

    Energy Technology Data Exchange (ETDEWEB)

    Saoudi, M.; Deportes, J.; Ouladdiaf, B. E-mail: ouladdiaf@ill.fr

    2001-06-01

    The magnetic ground states of the Laves phases Ti{sub 1-x}Sc{sub x}Fe{sub 2} system have been investigated by means of powder neutron diffraction and magnetisation techniques. For x=0.23, a transition is observed from a collinear ferromagnet along the c-axis to a canted one at T{sub f}=200 K. For x=0.27, 0.3, 0.33, an additional first-order transition is observed at T{sub t1}{approx}120 K accompanied by a large magnetovolume anomaly associated to a jump of the magnetic moment of the Fe atoms at the 2a site. The magnetic moment instability in a frustrated lattice should be considered to interpret this transition, although most of the other magnetic states can be discussed within Moriya's theory for itinerant electron systems with competing ferromagnetic and antiferromagnetic spin fluctuations.

  3. Kinetics of Photocatalytic Degradation of Methylene Blue Over CaTiO3

    Institute of Scientific and Technical Information of China (English)

    HAN Chong; YANG He; XUE Xiangxin

    2015-01-01

    Kinetics of photocatalytic degradation of methylene blue (MB) over CaTiO3 was studied. Effects of the solution pH, the MB concentration, the CaTiO3 dosage, and the type of light source on photocatalytic degradation rate of MB over CaTiO3 were investigated in detail. The results show that photocatalytic degradation of MB over CaTiO3 followed the first-order reaction. The apparent rate constant (kobs) of MB signiifcantly increased with increasing solution pH while it greatly decreased with increasing MB concentration. Thekobs of MB increased with increasing CaTiO3 dosage from 0.05 to 0.1 g, whereas it slightly decreased with increasing CaTiO3 dosage in the range of 0.1-0.4 g. Thekobs of MB under UV-visible light irradiation was larger by factors of 2.2 than that under visible light irradiation. Thekobs of MB was (4.8±0.3)×10-1 h-1 under optimal conditions with the solution pH of 11, the MB concentration of 1 ppm, the CaTiO3 dosage of 0.1 g, and UV-visible light irradiation.

  4. Dust depletion of Ca and Ti in QSO absorption line systems

    CERN Document Server

    Guber, C R

    2016-01-01

    To explore the role of titanium- and calcium-dust depletion in gas in and around galaxies we systematically study Ti/Ca abundance ratios in intervening absorption-line systems at low and high redshift. We investigate high-resolution optical spectra obtained by the UVES instrument at the Very Large Telescope and spectroscopically analyze 34 absorption-line systems at z<=0.5 to measure column densities (or limits) for CaII and TiII. We complement our UVES data set with previously published absorption-line data on Ti/Ca for redshifts up to z~3.8. Our absorber sample contains 110 absorbers (DLAs, sub-DLAs & LLSs). We compare our Ti/Ca findings with results from the Milky Way and the Magellanic Clouds and discuss the properties of Ti/Ca absorbers in the general context of quasar absorption-line systems.Our analysis indicates that there are two distinct populations of absorbers with either high or low Ti/Ca ratios with a separation at [Ti/Ca}]~1. While the calcium dust depletion in most of the absorbers appe...

  5. Bingel-Hirsch reaction mechanisms on TiSc2N@Ih-C80: the role of endohedral titanium nitride.

    Science.gov (United States)

    Zhao, Pei; Dang, Jing-Shuang; Zhao, Xiang

    2016-04-14

    Recently, two unconventional singly bonded monoadducts of mixed-metal nitride clusterfullerene TiSc2N@Ih-C80 have been synthesized. Herein, the site-selectivity and kinetic processes of Bingel-Hirsch reactions are explored by density functional theory calculations. Because of the rotation of the inner TiSc2N unit, two different types of singly bonded monoadducts (named 666 and 566 adducts) are clarified. Meanwhile, the two functionalized sites are situated above the Ti-Sc edge of the inner cluster in singly bonded adducts. Addition on the triple-fused-hexagon site (6-6-6 site) is found to be kinetically preferred, which can be attributed to the more positive charge of the carbon in the 6-6-6 site. In addition, we investigated the formation process of two conventional cycloadducts. A preference for the addition on the bridged hexagon-hexagon bond is concluded in theory, furthermore, one Sc atom instead of the Ti atom is pointing to the functionalized bond for the lowest-energy orientational product.

  6. Thermoelastic properties of ScB2, TiB2, YB4 and HoB4: Experimental and theoretical studies

    DEFF Research Database (Denmark)

    Waśkowska, A.; Gerward, Leif; Staun Olsen, J.

    2011-01-01

    High-pressure X-ray diffraction in ScB2, TiB2, YB4 and HoB4 powders and single crystals has been studied using synchrotron radiation as well as conventional X-rays. The experimental results are supported by calculations using density functional theory. ScB2, YB4 and HoB4 are hard materials (bulk...... modulus 180–200 GPa), while TiB2 may be classified as superhard (bulk modulus about 260 GPa). We report here first experimental and theoretical determinations of the bulk modulus for HoB4 (195(5) and 198.2 GPa, respectively), and first experimental values of the bulk modulus for ScB2 (196(2) GPa) and YB4...

  7. Tuning of Photoluminescence by Cation Nanosegregation in the (CaMg)(x)(NaSc)(1-x)Si2O6 Solid Solution.

    Science.gov (United States)

    Xia, Zhiguo; Liu, Guokui; Wen, Jianguo; Mei, Zhigang; Balasubramanian, Mahalingam; Molokeev, Maxim S; Peng, Licong; Gu, Lin; Miller, Dean J; Liu, Quanlin; Poeppelmeier, Kenneth R

    2016-02-03

    Controlled photoluminescence tuning is important for the optimization and modification of phosphor materials. Herein we report an isostructural solid solution of (CaMg)x(NaSc)1-xSi2O6 (0 solid solution is energetically unstable. It is shown that nanosegregation allows predictive control of color rendering and therefore provides a new method of phosphor development.

  8. Direct Extraction of Ti and Ti Alloy from Ti-Bearing Dust Slag in Molten CaCl2

    Science.gov (United States)

    Chen, Chaoyi; Zhao, Chong; Li, Junqi; Yang, Shufeng

    2016-06-01

    Using process of solid oxygen-ion conducting membrane (SOM), titanium metal and its alloy can be prepared directly from Ti-bearing dust slag by immersing it in the molten CaCl2 at 1,100℃, which has been proposed by constant voltage of 3.5 V for 2-6 h. The dust slag was ball-milled and pressed into pellets, then employed as the cathode, while the liquid copper, which was saturated with graphite powder and encased in yttria-stabilized zirconia (YSZ) tube, acted as the anode. The effect of forming pressure and electrolytic time on products was analyzed. The results show that the content of titanium increased with electrolytic time and the characteristic morphology presents as granule. Ti-Fe alloy can be obtained from Ti-Fe residue by 6 h electrolysis. For titanium-rich residue, when the forming pressure of pellets decreased from 6 to 3 MPa, only electrolysis for more than 4 h can completely remove the oxygen, and pure titanium is obtained by 6 h electrolysis. Besides, there is an unprecedented finding that the porous cathode is conducive to the removal of impurity elements.

  9. Dielectric properties of CaCu2.9Co0.1Ti4O12 and CaCu3Ti3.9Co0.1O12 ceramics synthesized by semi-wet route

    Indian Academy of Sciences (India)

    K D Mandal; Alok Kumar Rai; Laxman Singh; Om Parkash

    2012-06-01

    The effect of Co+2 doping on Cu+2 and Ti+4 sites in calcium copper titanate, CaCu3Ti4O12, has been examined. The doped compositions, CaCu3−CoTi4O12 and CaCu3Ti4−CoO12 ( = 0.10) ceramics, were prepared by novel semi-wet route. In this method, calcium, copper and cobalt salts were taken in solution form and TiO2 was used in solid form. XRD analysis confirmed the formation of single-phase materials. Structure of CaCu3Ti4O12 does not change on doping with cobalt either on Cu-site or Ti-site and it remains cubic. Scanning electron micrographs (SEM) show average grain size of CaCu2.9Co0.1Ti4O12 to be larger than CaCu3Ti3.9Co0.1O12 ceramic. Energy dispersive X-ray spectroscopy (EDX) studies confined the purity of parent and Co-doped CaCu3Ti4O12 ceramics. Dielectric constant (r) and dielectric loss (tan ) of CaCu2.9Co0.1Ti4O12 is comparatively higher than that of CaCu3Ti3.9Co0.1O12 ceramic at all measured frequencies and temperatures.

  10. Magnetism and electronic structure of (001)- and (111)-oriented LaTiO{sub 3} bilayers sandwiched in LaScO{sub 3} barriers

    Energy Technology Data Exchange (ETDEWEB)

    Weng, Yakui; Dong, Shuai, E-mail: sdong@seu.edu.cn [Department of Physics and Jiangsu Key Laboratory of Advanced Metallic Materials, Southeast University, Nanjing 211189 (China)

    2015-05-07

    In this study, the magnetism and electronic structure of LaTiO{sub 3} bilayers along both the (001) and (111) orientations are calculated using the density functional theory. The band insulator LaScO{sub 3} is chosen as the barrier layer and substrate to obtain the isolating LaTiO{sub 3} bilayer. For both the (001)- and (111)-oriented cases, LaTiO{sub 3} demonstrates the G-type antiferromagnetism as the ground state, similar to the bulk material. However, the electronic structure is significantly changed. The occupied bands of Ti are much narrower in the (111) case, giving a nearly flat band. As a result, the exchange coupling between nearest-neighbor Ti ions is reformed in these superlattices, which will affect the Néel temperature significantly.

  11. Elastic and anelastic anomalies in (Ca,Sr)TiO perovskites: Analogue behaviour for silicate perovskites

    OpenAIRE

    Walsh, J.W.; Taylor, P.A.; Buckley, A.; Darling, T.W.; Schreuer, J.; Carpenter, M.A.

    2008-01-01

    Elastic and anelastic anomalies in (Ca,Sr)TiO3 perovskites: Analogue behaviour for silicate perovskites UNITED KINGDOM (Walsh, J.W.) UNITED KINGDOM Received: 2007-10-30 Revised: 2008-02-18 Accepted: 2008-02-27

  12. Processing and characterization of CaTiO3 perovskite ceramics

    Directory of Open Access Journals (Sweden)

    Guilherme Gralik

    2014-06-01

    Full Text Available Calcium titanate (CaTiO3 ceramics with perovskite structure were produced by solid state reaction. Calcium carbonate (CaCO3 and titanium dioxide (TiO2 were mixed (in molar ratios 1/1 and 3/2, and the obtained mixtures were calcined at 1150 °C in successive thermal cycles. The obtained samples were characterized by differential thermal analysis, thermogravimetry, X-ray diffraction, measurement of particle size distribution and linear thermal shrinkage. XRD results indicated that the samples have perovskite CaTiO3 structure with small amount of secondary CaO and TiO2 phases, and their phase composition depends on the heat treatment conditions. The measured values of electrical resistivity were within the characteristic range of insulating materials and approach values corresponding to semiconducting ceramics.

  13. Microstructure and transformation behavior of Ni{sub 24.7}Ti{sub 50.3}Pd{sub 25} high temperature shape-memory alloy with Sc micro-addition

    Energy Technology Data Exchange (ETDEWEB)

    Ramaiah, K.V., E-mail: kvramaiah@nal.res.in [Materials Science Division, CSIR-National Aerospace Laboratories, Bangalore 560 017 (India); Saikrishna, C.N. [Materials Science Division, CSIR-National Aerospace Laboratories, Bangalore 560 017 (India); Gouthama [Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur 208 016 (India); Bhaumik, S.K. [Materials Science Division, CSIR-National Aerospace Laboratories, Bangalore 560 017 (India)

    2015-08-15

    NiTiPd shape-memory alloys (SMAs) are potential functional materials for use as solid-state actuators in the temperature range 100–250 °C. The present study investigates the effect of 1.0 at.% Sc micro-addition to Ni{sub 24.7}Ti{sub 50.3}Pd{sub 25} alloy, Sc replacing either Ti or Ni. Results show that all the three alloys studied have stable transformation behavior on stress-free thermal cycling and hence, are suitable for cyclic actuation applications. However, the addition of Sc to NiTiPd alloy leads to decrease of transformation temperatures, the magnitude of decrease being greater for the alloy with Sc replacing Ni. The martensite finish (M{sub f}) temperature of 181 °C for the NiTiPd alloy decreased to 139 °C for Sc replacing Ti and 83 °C for Sc replacing Ni. Also, the indentation modulus of NiTiPdSc (Sc replacing Ni) alloy is found to be significantly low compared to the other alloys. Analysis indicates that the observed differences in the alloy properties are related to the solubility of Sc in the NiTiPd matrix. While the quaternary NiTiPdSc alloy, Sc replacing Ti, has a single phase microstructure, the alloy with Sc replacing Ni shows the presence of Sc-rich and TiPd-type second phases in the microstructure. TEM examination revealed that the TiPd-type phase has a distinct rod-like morphology (30–50 nm) arranged in a grid-like structure. The transformation and indentation behavior of the alloys is elucidated using thermodynamic calculations of frictional energy and an electronic structure based analysis. - Highlights: • TEM of Ni{sub 23.7}Ti{sub 50.3}Pd{sub 25}Sc{sub 1} showed distinct grid of TiPd-type phase nanorods < 50 nm. • Stress-free thermal cycling of all the three alloys showed stable transformation behavior. • Ni{sub 24.7}Ti{sub 49.3}Pd{sub 25}Sc{sub 1} and Ni{sub 23.7}Ti{sub 50.3}Pd{sub 25}Sc{sub 1} showed single and multiphase structures. • Sc micro-addition (1 at.%) to Ni{sub 24.7}Ti{sub 50.3}Pd{sub 25} alloy decreased TTs

  14. A study of the crystal structures and the phase transitions of the ordered double perovskites Sr{sub 2}ScSbO{sub 6} and Ca{sub 2}ScSbO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Faik, A., E-mail: afaik@cicenergigune.com [Fisika Aplikatua II Saila, Zientzia eta Teknologia Fakultatea, Euskal Herriko Unibertsitatea, P.O.Box 644, Bilbao 48080 (Spain); CICenergigune, Parque Tecnologico, Albert Einstein 48, 01510 Minano, Alava (Spain); Orobengoa, D. [Departamento de Fisica de la Materia Condensada, Universidad del Pais Vasco, E-48080 Bilbao (Spain); Iturbe-Zabalo, E.; Igartua, J.M. [Fisika Aplikatua II Saila, Zientzia eta Teknologia Fakultatea, Euskal Herriko Unibertsitatea, P.O.Box 644, Bilbao 48080 (Spain)

    2012-08-15

    The crystal structures and phase transitions of the two ordered double perovskites Sr{sub 2}ScSbO{sub 6} and Ca{sub 2}ScSbO{sub 6} were studied using conventional X-ray and neutron powder-diffraction methods. The crystal structures of both compounds have the P2{sub 1}/n space group symmetry at room temperature, resulting from Sc/Sb ordering. The evolution with temperature of the structure of the Sr containing compound shows the presence of three phase transitions with the following sequence: P2{sub 1}/n{yields}I2/m{yields}I4/m{yields}Fm3{sup Macron }m, at about 400, 560 and 650 K, respectively. The smaller size of Ca cation, with respect to that of Sr cation, leads to a large distortion of Ca{sub 2}ScSbO{sub 6} at room temperature. This fact in turn causes that the Ca containing compound shows only the first phase transition from P2{sub 1}/n to I2/m at high temperature at about 1440 K. The analysis of the phase transitions and the refinements have done using the symmetry-adapted modes and the tools of the Bilbao Crystallographic Server. - Graphical abstract: Representation of the new structure resulting from the coupling of the unidimensional GM{sup 4+} and X{sup 3+} modes with the a{sup +}b{sup -}b{sup -} tilting scheme associated to P2{sub 1}/n and the temperature evolution of the amplitudes of the GM{sup 1+}, GM{sup 3+}, GM{sup 4+} and GM{sup 5+} modes of I2/m and I4/m space groups obtained from the NPD data of Sr{sub 2}ScSbO{sub 6}. Highlights: Black-Right-Pointing-Pointer Study of two compounds of the antimony double perovskite family. Black-Right-Pointing-Pointer Determination of the structures at room temperature. Black-Right-Pointing-Pointer Determination of high-temperature phase transitions by X-ray and neutron powder diffraction. Black-Right-Pointing-Pointer Using the symmetry-adapted modes to study the phase transitions.

  15. Growth of Araucaria angustifolia in the Embrapa/Epagri forest reserve, Caçador, SC, Brazil Crescimento de Araucaria angustifolia na Reserva Florestal Embrapa/ Epagri, Caçador, SC

    Directory of Open Access Journals (Sweden)

    Patricia Póvoa de Mattos

    2010-06-01

    Full Text Available Araucaria Forest is one of most threatened phyto-physiognomies in the Atlantic Forest domain,
    presenting great ecological-economical importance. Nevertheless, there are still lacks of knowledge concerning growth and dynamic of important species, as Araucaria angustifolia. The objective of this work was to recover  the past growth of Araucaria angustifolia, native from Caçador, SC, Brazil, by measuring growth rings and to estimate the average periodic diametric increment. The growth rings were counted and measured, using a stereoscope microscope, in increment cores of 0.5 cm collected from 32 adult trees. The measurements were done with LINTAB measuring table, with 0.01 mm of precision. The samples sizes were irregular, varying from 4.2 to 20.2 cm long. The trees presented average diameter breast height (DBH of 76.3 cm, varying from 10.7 to 141.3 cm. The periodic diameter increment from the last 10 years was 0.4 cm, varying from 0.11 to 1.15 cm. It was observed differences among trees, but there was a tendency of reduction of growth rhythm in larger trees, being more
    evident in trees with more than 110 cm of DBH.A Floresta Ombrófila Mista (FOM é uma das fitofisionomias mais ameaçadas da área de domínio da
    Mata Atlântica, apresentando grande importância ecológico-econômica. Apesar disso, ainda existem lacunas de conhecimento sobre a produtividade primária, o crescimento e a dinâmica de espécies importantes, como a Araucaria angustifolia. O presente trabalho tem por objetivo estudar o crescimento anual de Araucaria angustifolia, nativa do Município de Caçador, SC, pela medição dos anéis de crescimento. A contagem e medição dos anéis de crescimento foram feitas com o auxílio de um microscópio estereoscópico, em baguetas de 0,5 cm de diâmetro, coletadas de 32 árvores adultas. As medições foram feitas com o medidor de anéis de crescimento LINTAB, com precisão de 0,01 mm. O comprimento das amostras

  16. Photocatalytic activity of Fe-doped CaTiO₃ under UV-visible light.

    Science.gov (United States)

    Yang, He; Han, Chong; Xue, Xiangxin

    2014-07-01

    The photocatalytic degradation of methylene blue (MB) over Fe-doped CaTiO₃ under UV-visible light was investigated. The as-prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) system, Fourier transform infrared spectra (FT-IR), and UV-visible diffuse reflectance spectroscopy (DRS). The results show that the doping with Fe significantly promoted the light absorption ability of CaTiO₃ in the visible light region. The Fe-doped CaTiO₃ exhibited higher photocatalytic activity than CaTiO₃ for the degradation of MB. However, the photocatalytic activity of the Fe-doped CaTiO₃ was greatly influenced by the calcination temperature during the preparation process. The Fe-doped CaTiO₃ prepared at 500°C exhibited the best photocatalytic activity, with degradation of almost 100% MB (10ppm) under UV-visible light for 180 min.

  17. Enhancing the photoluminescence intensity of CaTiO3:Eu3+ red phosphors with magnesium

    Institute of Scientific and Technical Information of China (English)

    张杰强; 范艳伟; 陈朝阳; 王军华; 赵鹏君; 郝斌

    2015-01-01

    Red phosphors MgxCa1–xTiO3:Eu3+ (0Ca0.6TiO3:0.03Eu3+ was 4.26 times of that of phosphor CaTiO3:0.03Eu3+. Based on these results, it implied that the PL intensity of phosphorCaTiO3:0.03Eu3+ could be significantly enhanced by introducing Mg2+ into CaTiO3 host lattices and the phosphor Mg0.4Ca0.6TiO3:0.03Eu3+ might be the promising red-emitting phosphor in making tricolor phosphor converted white-LEDs.

  18. CORRELATION OF {sup 48}Ca, {sup 50}Ti, AND {sup 138}La HETEROGENEITY IN THE ALLENDE REFRACTORY INCLUSIONS

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hsin-Wei; Lee, Typhoon; Lee, Der-Chuen; Chen, Jiang-Chang, E-mail: hart.chen@bristol.ac.uk [Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan, ROC (China)

    2015-06-10

    Precise determinations of {sup 48}Ca anomalies in Allende calcium–aluminum-rich inclusions (CAIs) are reported in this work. There are endemic positive {sup 48}Ca/{sup 44}Ca anomalies in all analyzed CAIs after normalization to {sup 42}Ca/{sup 44}Ca, and it is clearly shown that there is no simple correlation between {sup 48}Ca/{sup 44}Ca and {sup 50}Ti/{sup 48}Ti anomalies, in agreement with Jungck et al. Compared to the {sup 48}Ca/{sup 44}Ca versus {sup 50}Ti/{sup 48}Ti correlation line defined by differentiated meteorites, reported by Chen et al., the CAIs plot to elevated {sup 50}Ti/{sup 48}Ti. Assuming the {sup 48}Ca/{sup 44}Ca anomalies of both CAIs and differentiated meteorites came from the same source, excess {sup 50}Ti anomalies in CAIs can be calculated by subtracting the part associated with {sup 48}Ca/{sup 44}Ca. These excesses show a linear correlation with {sup 138}La anomalies, a neutrino-process nuclide. According to current stellar nucleosynthetic models, we therefore suggest that the solar system {sup 48}Ca, {sup 50}Ti, and {sup 138}La isotopic variations are made of mixtures between grains condensed from ejecta of neutron-rich accretion-induced SNe Ia and the O/Ne–O/C zone of core-collapse SNe II.

  19. Wear Behavior of Cold Pressed and Sintered Al2O3/TiC/CaF2Al2O3/TiC Laminated Ceramic Composite

    Institute of Scientific and Technical Information of China (English)

    Xuefeng YANG; Jian CHENG; Peilong SONG; Shouren WANG; Liying YANG; Yanjun WANG; Ken MAO

    2013-01-01

    A novel laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite was fabricated through cold pressing and sintering to achieve better anti-wear performance,such as low friction coefficient and low wear rate.Al2O3/TiC/CaF2 and Al2O3/TiC composites were alternatively built layer-by-layer to obtain a sandwich structure.Solid lubricant CaF2 was added evenly into the Al2O3/TiC/CaF2 layer to reduce the friction and wear.Al2O3/TiC ceramic was also cold pressed and sintered for comparison.Friction analysis of the two ceramics was then conducted via a wear-and-tear machine.Worn surface and surface compositions were examined by scanning electron microscopy and energy dispersion spectrum,respectively.Results showed that the laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite has lower friction coefficient and lower wear rate than those of Al2O3/TiC ceramic alone because of the addition of CaF2 into the laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite.Under the friction load,the tiny CaF2 particles were scraped from the Al2O3/TiC/CaF2 layer and spread on friction pairs before falling off into micropits.This process formed a smooth,self-lubricating film,which led to better anti-wear properties.Adhesive wear is the main wear mechanism of Al2O3/TiC/CaF2 layer and abrasive wear is the main wear mechanism of Al2O3/TiC layer.

  20. Enhanced High Temperature Piezoelectrics Based on BiScO3-PbTiO3 Ceramics

    Science.gov (United States)

    Sehirlioglu, Alp; Sayir, Ali; Dynys, Fred

    2009-01-01

    High-temperature piezoelectrics are a key technology for aeronautics and aerospace applications such as fuel modulation to increase the engine efficiency and decrease emissions. The principal challenge for the insertion of piezoelectric materials is the limitation on upper use temperature which is due to low Curie-Temperature (TC) and increasing electrical conductivity. BiScO3-PbTiO3 (BS-PT) system is a promising candidate for improving the operating temperature for piezoelectric actuators due to its high TC (greater than 400 C). Bi2O3 was shown to be a good sintering aid for liquid phase sintering resulting in reduced grain size and increased resistivity. Zr doped and liquid phase sintered BS-PT ceramics exhibited saturated and square hysteresis loops with enhanced remenant polarization (37 microC per square centimeter) and coercive field (14 kV/cm). BS-PT doped with Mn showed enhanced field induced strain (0.27% at 50kV/cm). All the numbers indicated in parenthesis were collected at 100 C.

  1. Vibrational properties of Ca{sub 3}Sc{sub 2}Ge{sub 3}O{sub 12}, a garnet host crystal for laser applications

    Energy Technology Data Exchange (ETDEWEB)

    Cavalli, Enrico [Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica e Chimica Fisica, Universita di Parma, Parma (Italy)]. E-mail: cavalli@ipruniv.cce.unipr.it; Zannoni, Ester [Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica e Chimica Fisica, Universita di Parma, Parma (Italy); Bettinelli, Marco; Speghini, Adolfo [Dipartimento Scientifico e Tecnologico, Universita di Verona Ca Vignal, Verona (Italy); Tonelli, Mauro; Toncelli, Alessandra [INFM, Pisa (Italy); Dipartimento di Fisica, Universita di Pisa, Pisa (Italy)

    2000-05-29

    The IR and the Raman spectra of the Ca{sub 3}Sc{sub 2}Ge{sub 3}O{sub 12} (CaSGG) garnet crystal have been measured and discussed in terms of internal and external modes of the tetrahedral GeO{sup 4-}{sub 4} moiety. Some important aspects of the electronic spectroscopy of these materials activated with luminescent ions, i.e. the multiphonon relaxation of the excited states and the vibrational structure of the optical bands, have been taken into consideration, and correspondences with the vibrational properties of the host lattice have been presented. (author)

  2. Structure of 55Ti and 49Ca from relativistic one-neutron knockout

    CERN Document Server

    Maierbeck, P; Krücken, R; Kröll, T; Alvarez-Pol, H; Aksouh, F; Aumann, T; Behr, K; Benjamim, E A; Benlliure, J; Bildstein, V; Böhmer, M; Boretzky, K; García-Borge, M J; Brünle, A; Bürger, A; Caamaño, M; Casarejos, E; Chatillon, A; Chulkov, L V; Cortina-Gil, D; Enders, J; Eppinger, K; Fästermann, T; Friese, J; Fabbietti, L; Gascón, M; Geissel, H; Gerl, J; Górska, M; Hansen, P G; Jonson, B; Kanungo, R; Kiselev, O; Kojouharov, I; Klimkiewicz, A; Kurtukian, T; Kurz, N; Larsson, K; Bleis, T Le; Mahata, K; Maier, L; Nilsson, T; Nociforo, C; Nyman, G; Pascual-Izarra, C; Perea, A; Pérez, D; Prochazka, A; Rodriguez-Tajes, C; Rossi, D; Schaffner, H; Schrieder, G; Schwertel, S; Simon, H; Sitár, B; Stanoiu, M; Sümmerer, K; Tengblad, O; Weick, H; Winkler, S; Brown, B A; Otsuka, T; Tostevin, J; Rae, W D M

    2008-01-01

    Results are presented from a one-neutron knockout reaction at relativistic energies on 50Ca and 56Ti using the GSI FRS as a two-stage magnetic spectrometer and the Miniball array for gamma-ray detection. Inclusive and exclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the orbital angular momentum of the populated states. First-time observation of the 3.35(15) MeV nu f7/2-hole state in 49Ca and the 955(6) keV nu p3/2-hole state in 55Ti is reported. The measured data clearly indicates that the ground state of 55Ti is a 1/2- state, in agreement with shell-model calculations using the GXPF1A interaction that predict a sizable N=34 gap in 54Ca.

  3. Optical spectroscopy and band gap analysis of hybrid improper ferroelectric Ca3Ti2O7

    Science.gov (United States)

    Cherian, Judy G.; Birol, Turan; Harms, Nathan C.; Gao, Bin; Cheong, Sang-Wook; Vanderbilt, David; Musfeldt, Janice L.

    2016-06-01

    We bring together optical absorption spectroscopy, photoconductivity, and first principles calculations to reveal the electronic structure of the room temperature ferroelectric Ca3Ti2O7. The 3.94 eV direct gap in Ca3Ti2O7 is charge transfer in nature and noticeably higher than that in CaTiO3 (3.4 eV), a finding that we attribute to dimensional confinement in the n = 2 member of the Ruddlesden-Popper series. While Sr substitution introduces disorder and broadens the gap edge slightly, oxygen deficiency reduces the gap to 3.7 eV and gives rise to a broad tail that persists to much lower energies.

  4. Orbital configuration in CaTiO3 films on NdGaO3

    Science.gov (United States)

    Cao, Yanwei; Park, Se Young; Liu, Xiaoran; Choudhury, D.; Middey, S.; Meyers, D.; Kareev, M.; Shafer, P.; Arenholz, E.; Chakhalian, J.

    2016-10-01

    Despite its use as a constituent layer for realization of a polar metal and interfacial conductivity, the microscopic study of electronic structure of CaTiO3 is still very limited. Here, we epitaxially stabilized CaTiO3 films on NdGaO3 (110) substrates in a layer-by-layer way by pulsed laser deposition. The structural and electronic properties of the films were characterized by reflection-high-energy-electron-diffraction, X-ray diffraction, and element-specific resonant X-ray absorption spectroscopy. To reveal the orbital polarization and the crystal field splitting of the titanium 3d state, X-ray linear dichroism was carried out on CaTiO3 films, demonstrating the orbital configuration of dxz/dyz < dxy < d3 z2-r2 < dx2-y2 . To further explore the origin of this configuration, we performed the first-principles density function theory calculations, which linked the orbital occupation to the on-site energy of Ti 3d orbitals. These findings can be important for understanding and designing exotic quantum states in heterostructures based on CaTiO3.

  5. Vacancy induced metallicity at the CaHfO3/SrTiO3 interface

    KAUST Repository

    Nazir, Safdar

    2011-03-31

    Density functional theory is used to study the electronic properties of the oxide heterointerfaceCaHfO3/SrTiO3. Structural relaxation is carried out with and without O vacancies. As compared to related interfaces, strongly reduced octahedral distortions are found. Stoichiometric interfaces between the wide band gap insulatorsCaHfO3 and SrTiO3 turn out to exhibit an insulating state. However, interface metallicity is introduced by O vacancies, in agreement with experiment. The reduced octahedral distortions and necessity of O deficiency indicate a less complicated mechanism for the creation of the interfacial electron gas.

  6. New Infrared Properties of the Tetragonal CaTiO3

    Institute of Scientific and Technical Information of China (English)

    YI Lin; DUAN Yi-Feng

    2005-01-01

    @@ First-principle calculations are performed to study the infrared optical and electronic properties of the tetragonal CaTiO3.We find that dielectric function and reflectivity exhibit a new single-peak infrared spectrum.It is shown that strong orbital hybridization can form the dipole distribution of covalent bonds (Ti-O1 and Ti-O2)and can result in anomalous optical behaviour.The tetragonal structure that determines the dipole configuration and leads to the optical dipole-dipole transition forbidden is therefore realized to be vital to cause such optical phenomena with the insulator feature.

  7. Solid state reaction synthesis and photoluminescence properties of Dy{sup 3+} doped Ca{sub 3}Sc{sub 2}Si{sub 3}O{sub 12} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Long, Qiang; Wang, Chuang; Li, Yanyan; Ding, Jianyan; Wang, Xicheng; Wang, Yuhua, E-mail: wyh@lzu.edu.cn

    2015-11-15

    Highlights: • Ca{sub 3−x}Sc{sub 2}Si{sub 3}O{sub 12}:xDy{sup 3+} (0.01 ≤ x ≤ 0.03) was successfully synthesized under a reducing atmosphere. • The thermal stability of the Ca{sub 2.975}Sc{sub 2}Si{sub 3}O{sub 12}:0.025Dy{sup 3+} is superior to commercial phosphors in theory and experiment. • The optimal chromaticity coordinates of Ca{sub 3}Sc{sub 2}Si{sub 3}O{sub 12}:Dy{sup 3+} is (x = 0.3425, y = 0.3343) upon 350 nm excitation. - Abstract: The white emission phosphor Ca{sub 3}Sc{sub 2}Si{sub 3}O{sub 12}:Dy{sup 3+} was synthesized by the solid-state reaction. Phase analysis and characteristic luminescence properties are investigated by X-ray diffraction and photoluminescence spectra measurement. Ca{sub 3}Sc{sub 2}Si{sub 3}O{sub 12}:Dy{sup 3+} phosphor shows strong absorption in 350–410 nm region and exhibits white emission with CIE chromaticity coordinates of (0.3425, 0.3343). Its emission intensity at 250 °C remained 74% of that measured at room temperature. Moreover, the activation energy is also calculated through the Arrhenius equation. The result shows that the thermostability of Ca{sub 3}Sc{sub 2}Si{sub 3}O{sub 12}:Dy{sup 3+} is superior than that of commercial phosphor Ca{sub 3}Sc{sub 2}Si{sub 3}O{sub 12}:Ce{sup 3+}. The outstanding luminescent properties indicate that Ca{sub 3}Sc{sub 2}Si{sub 3}O{sub 12}:Dy{sup 3+} could be a potential white light emission phosphor.

  8. Electrochemically triggered release of acetylcholine from scCO2 impregnated conductive polymer films evokes intracellular Ca(2+) signaling in neurotypic SH-SY5Y cells.

    Science.gov (United States)

    Löffler, Susanne; Seyock, Silke; Nybom, Rolf; Jacobson, Gunilla B; Richter-Dahlfors, Agneta

    2016-12-10

    Implantable devices for electronically triggered drug release are attractive to achieve spatial and temporal control over drug concentrations in patients. Realization of such devices is, however, associated with technical and biological challenges. Among these are containment of drug reservoirs, lack of precise control cues, as well as the charge and size of the drug. Here, we present a method for electronically triggered release of the quaternary ammonium cation acetylcholine (ACh) from an impregnated conductive polymer film. Using supercritical carbon dioxide (scCO2), a film of PEDOT/PSS (poly(3,4)-ethylenedioxythiophene doped with poly(styrenesulfonate)) is impregnated with the neurotransmitter acetylcholine. The gentle scCO2 process generated a dry, drug-impregnated surface, well suited for interaction with biological material, while maintaining normal electrochemical properties of the polymer. Electrochemical switching of impregnated PEDOT/PSS films stimulated release of ACh from the polymer matrix, likely due to swelling mediated by the influx and efflux of charged and solvated ions. Triggered release of ACh did not affect the biological activity of the drug. This was shown by real-time monitoring of intracellular Ca(2+) signaling in neurotypic cells growing on the impregnated polymer surface. Collectively, scCO2 impregnation of conducting polymers offers the first one-step, dopant-independent drug impregnation process, potentially facilitating loading of both anionic and cationic drugs that can be dissolved in scCO2 on its own or by using a co-solvent. We foresee that scCO2-loaded devices for electronically triggered drug release will create novel opportunities when generating active bio-coatings, tunable for specific needs, in a variety of medical settings.

  9. Fluoride evaporation and crystallization behavior of CaF2-CaO-Al2O3-(TiO2) slag for electroslag remelting of Ti-containing steels

    Science.gov (United States)

    Shi, Cheng-bin; Cho, Jung-wook; Zheng, Ding-li; Li, Jing

    2016-06-01

    To elucidate the behavior of slag films in an electroslag remelting process, the fluoride evaporation and crystallization of CaF2-CaO-Al2O3-(TiO2) slags were studied using the single hot thermocouple technique. The crystallization mechanism of TiO2-bearing slag was identified based on kinetic analysis. The fluoride evaporation and incubation time of crystallization in TiO2-free slag are found to considerably decrease with decreasing isothermal temperature down to 1503 K. Fish-bone and flower-like CaO crystals precipitate in TiO2-free slag melt, which is accompanied by CaF2 evaporation from slag melt above 1503 K. Below 1503 K, only near-spherical CaF2 crystals form with an incubation time of less than 1 s, and the crystallization is completed within 1 s. The addition of 8.1wt% TiO2 largely prevents the fluoride evaporation from slag melt and promotes the slag crystallization. TiO2 addition leads to the precipitation of needle-like perovskite (CaTiO3) crystals instead of CaO crystals in the slag. The crystallization of perovskite (CaTiO3) occurs by bulk nucleation and diffusion-controlled one-dimensional growth.

  10. Fluoride evaporation and crystallization behavior of CaF2-CaO-Al2O3-(TiO2) slag for electroslag remelting of Ti-containing steels

    Institute of Scientific and Technical Information of China (English)

    Cheng-bin Shi; Jung-wook Cho; Ding-li Zheng; Jing Li

    2016-01-01

    To elucidate the behavior of slag films in an electroslag remelting process, the fluoride evaporation and crystallization of CaF2–CaO–Al2O3–(TiO2) slags were studied using the single hot thermocouple technique. The crystallization mechanism of TiO2-bearing slag was identified based on kinetic analysis. The fluoride evaporation and incubation time of crystallization in TiO2-free slag are found to considerably decrease with decreasing isothermal temperature down to 1503 K. Fish-bone and flower-like CaO crystals precipitate in TiO2-free slag melt, which is accompanied by CaF2 evaporation from slag melt above 1503 K. Below 1503 K, only near-spherical CaF2 crystals form with an incubation time of less than 1 s, and the crystallization is completed within 1 s. The addition of 8.1wt% TiO2 largely prevents the fluoride evaporation from slag melt and promotes the slag crystallization. TiO2 addition leads to the precipitation of needle-like perovskite (CaTiO3) crystals instead of CaO crystals in the slag. The crystallization of perovskite (CaTiO3) occurs by bulk nucleation and diffusion-controlled one-dimensional growth.

  11. The energy transfer and effect of doped Mg2+ in Ca3Sc2Si3O12:Ce3+, Pr3+ phosphor for white LEDs.

    Science.gov (United States)

    Qiao, Jun; Zhang, Jiahua; Zhang, Xia; Hao, Zhendong; Liu, Yongfu; Luo, Yongshi

    2014-03-14

    The energy transfer and luminescence properties in the Ce(3+) and Pr(3+) co-activated Ca3Sc2Si3O12 (CSS) silicate garnet are studied in our work. The addition of Pr(3+) exhibits a red emission around 610 nm in the green phosphor CSS:Ce(3+), but the amount of Pr(3+) incorporated into the phosphor is very limited due to the charge mismatch when Pr(3+) substitutes for Ca(2+) in CSS. In order to promote Pr(3+) incorporation into CSS lattices to enhance the red emission component, the addition of Mg(2+) incorporated into Sc(3+) site is performed to compensate the residual positive charge caused by the substitution of Pr(3+) for Ca(2+) in CSS. Finally, a white LED with color rendering index of 80 and correlated color temperature of 8715 K is obtained by combining the single CSS:0.05Ce(3+), 0.01Pr(3+), 0.3Mg(2+) phosphor with a blue-emitting InGaN LED chip.

  12. Influence of Phase Transformations on Crystal Growth of Stoichiometric Brownmillerite Oxides: Sr2ScGaO5 and Ca2Fe2O5

    Directory of Open Access Journals (Sweden)

    Monica Ceretti

    2016-11-01

    Full Text Available High quality stoichiometric brownmillerite-type oxide single crystals have been successfully grown by the floating zone method using a mirror furnace. We report here on the growth conditions and structural characterization of two model compounds: Ca2Fe2O5 and Sr2ScGaO5. Both show oxygen deficiency with respect to the average perovskite structure, and are promising candidates for oxygen ion conductivity at moderate temperatures. While Sr2ScGaO5 single crystals were obtained in the cubic oxygen-deficient perovskite structure, Ca2Fe2O5 crystallizes in the brownmillerite framework. Having no cubic parent high temperature counterpart, Ca2Fe2O5 crystals were found to be not twinned. We report on structural characterization of the as-grown single crystals by neutron and X-ray diffraction, as well as scanning electron microscopy (SEM coupled with EDX (Energy Dispersive X-Ray Spectroscopy analysis and isotope exchange experiments.

  13. Fabrication of Ag-Decorated CaTiO₃ Nanoparticles and Their Enhanced Photocatalytic Activity for Dye Degradation.

    Science.gov (United States)

    Xian, T; Yang, H; Huo, Y S; Ma, J Y; Zhang, H M; Su, J Y; Feng, W J

    2016-01-01

    CaTiO₃nanoparticles of 30-40 nm in size were synthesized via a polyacrylamide gel route. Ag nanoparticles with size of 8-16 nm were deposited onto CaTiO₃particles by a photochemical reduction method to yield CaTiO₃@Ag composites. The photocatalytic activity of prepared samples was evaluated by degrading methyl orange under ultraviolet irradiation. It is demonstrated that Ag-decorated CaTiO₃ particles exhibit an enhanced photocatalytic activity compared to bare CaTiO₃ particles. After 60 min of photocatalysis, the degradation percentage of MO increases from 54% for bare CaTiO₃particles to 72% for CaTiO₃@Ag composites. This can be explained by the fact that photogenerated electrons are captured by Ag nanoparticles and photogenerated holes are therefore increasingly available to react with OH⁻/H₂O to generate hydroxyl (·OH) radicals. ·OH radicals were detected by fluorimetry using terephthalic acid as a probe molecule, revealing an enhanced yield on the irradiated CaTiO₃@Ag composites. In addition, it is found that the addition of ethanol, which acts as an ·OH scavenger, leads to a quenching of ·OH radicals and simultaneous decrease in the photocatalytic efficiency. This suggests that ·OH radicals are the dominant active species responsible for the dye degradation.

  14. Improved photoluminescence of green-emitting phosphor Ca_3Sc_2Si_3O_(12):Ce~(3+) for white light emitting diodes

    Institute of Scientific and Technical Information of China (English)

    刘元红; 庄卫东; 胡运生; 高文贵

    2010-01-01

    Ca3Sc2Si3O12:Ce3+ phosphors with single-phase were successfully synthesized by a gel-combustion method.Annealing atmosphere greatly affected the luminescent properties of the phosphor.The intensity of absorption band at 450 nm was greatly increased with a reducing atmosphere,which was very suitable as a color converter in white LED.The absorption at 243 and 311 nm was gradually enhanced with a stronger reducing atmosphere and a new absorption peak at 362 nm appeared in N2+H2 mixing gas.The emission intensit...

  15. Study of synergistic effect of Sc and C co-doping on the enhancement of visible light photo-catalytic activity of TiO2

    Science.gov (United States)

    Nasir, Muhammad; Lei, Juying; Iqbal, Waheed; Zhang, Jinlong

    2016-02-01

    Scandium and carbon co-doped TiO2 catalyst was prepared through a simple sol-gel synthesis method by using scandium nitrate as scandium dopant precursor, glucose as carbon precursor and tetrabutyl orthotitanate as titanium precursor and calcined them at 450 °C for 3 h. The characterizations of the prepared samples were accomplished through X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence spectroscopy (PL), Fourier transformation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET). The X-ray diffraction results of the samples showed the decrease in the crystal size of the sample with the subsequent increase in the specific surface area as shown by Brunauer-Emmett-Teller. The UV-visible diffuse reflectance spectroscopy displayed the blue shift in the absorption together with the photoluminescence spectroscopy revealed the decrease in the recombination of electrons and holes by the addition of the scandium and then after the certain optimum value, the further increase of the scandium further increased the recombination of electrons and holes. The photo-catalytic activity of the samples was investigated with the help of photo-catalytic degradation of Acid orange 7 under visible light irradiation. The degradation of Acid orange 7 was highly increased for the Sc and C co-doped samples compared to the single C doped sample. And the sample 0.2 Sc/C-TiO2 had the maximum increase. The enhanced photo-catalytic performance was due the decrease of the crystal size, increase of the surface area, increase in the surface hydroxyl groups, and increase of the lifetime of the electrons and holes because of the synergistic effect of the Sc and C co-doping in TiO2.

  16. Effect of different dopants on the long lasting phosphorescence behavior of CaTiO3:Pr3+

    Institute of Scientific and Technical Information of China (English)

    HUANG Ping; WU Yaqiao; CUI Cai'e; GUO Jin

    2011-01-01

    In order to improve the luminescence properties of CaTiO3:Pr3+, a series of CaTiO3:Pr3+, such as CaTio.97Nb0.03O3:Pr3+, Ca0.8Zn0.2TiO3:Pr3+, Ca0.8Zn0.2Ti0.97Nb0.03O3:Pr3+ and B3+-doped Ca0.8Zn0.2Ti0.97Nb003O3: Pr3+ were prepared through conventional solid state reaction method.The results of the photoluminescence excitation and emission spectra showed that all the samples emitted red phosphorescence at 612 nm originating from 1D2 to 3H4 emission of Pr3+ under the 337 nm excitation. When examined by the X-ray diffraction (XRD), all the samples presented a predominant phase of CaTiO3 (JCPDS# 42-423) except Zn2+-doped samples which also revealed another phase of Zn2Ti3O8(JCPDS# 73-579). The results of the afterglow decay curves showed that co-doping Zn2+ ions, Nb5+ ions or adding a small amount of B3+ into Ca0.8Zn0.2Ti0.97Nb0.03O3:Pr3+ were effective in improving the photoluminescence properties of CaTiO3:Pr3+ phosphor. Thermoluminescence results showed that the trap existing in all the samples was the same as in CaTiO3:Pr3+ and doping singly Nb5+ or Zn2+ hardly changed the trap depth but co-doping Nb5+ and Zn2+ could modify the trapping level from 0.63 to 1.26 eV distinctively. In addition, adding a certain amount of B3+ into CTO-PZN could also deepen the trap depth.

  17. Green tide deactivation with layered-structure cuboids of Ag/CaTiO{sub 3} under UV light

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Soo-Wohn [Global Research Laboratory, Sun Moon University, Galsan-Ri, Tangjung-Myon, Asan Chungnam 336-708 (Korea, Republic of); Lozano-Sánchez, L.M. [División de Materiales Avanzados, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055 Col. Lomas 4a sección, C.P. 78216 San Luis Potosí, S.L.P. (Mexico); Rodríguez-González, V., E-mail: vicente.rdz@ipicyt.edu.mx [División de Materiales Avanzados, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055 Col. Lomas 4a sección, C.P. 78216 San Luis Potosí, S.L.P. (Mexico)

    2013-12-15

    Graphical abstract: Synergic reasons such as mass transfer, morphology, biocide properties, UV-A photoresponse, and electron trapping that reduce recombination on Ag/CaTiO{sub 3} nanocomposites, have the potential for the generation of reactive radicals that promote the fatal irreversible deactivation of Tetraselmis suecica algae in 12 min under UV-A irradiation. -- Highlights: • An alternative to deactivate harmful green tide is proposed by employing Ag/CaTiO{sub 3}. • Particles of perovskite-like have rectangular prisms morphology with AgNPs ∼13 nm. • The cuboids achieve complete inactivation of Tetraselmis suecica algae in 12 min. • AgNPs functionalization induce fatal irreversible damages on the algae surface. -- Abstract: In this work, an alternative to deactivate noxious green tide Tetraselmis suecica in the short-term is proposed by employing Perovskite-like cube-shaped, crystalline CaTiO{sub 3} semiconductors functionalized with atomic silver nanoparticles. CaTiO{sub 3} was prepared by a microwave-assisted hydrothermal method and then Ag{sup 0}NPs (1 wt% of CaTiO{sub 3}), were added by the photoreduction method. The XRD results show that crystalline CaTiO{sub 3} has an orthorhombic unit cell with a Perovskite-like structure. Images obtained by FESEM and HRTEM microscopies show well-faceted CaTiO{sub 3} rectangular prismatic morphology functionalizated with silver nanoparticles ∼13.5 nm. XPS and EDS-FESEM has confirmed the composition of CaTiO{sub 3} and silver occurring mainly as reduced metal. The UV inactivation of noxious T. suecica with Ag/CaTiO{sub 3} nanocomposites formed on bare materials results in complete deactivation of the algae in 12 min. The direct contact between harmful algae and Ag/CaTiO{sub 3} nanocomposite is necessary to deactivate the algae and inhibits algae viability.

  18. Local character of the highest antiferromagnetic temperature of Ce systems in Sc-rich CeTi1 -xScxGe

    Science.gov (United States)

    Sereni, J. G.; Pedrazzini, P.; Gómez Berisso, M.; Chacoma, A.; Encina, S.; Gruner, T.; Caroca-Canales, N.; Geibel, C.

    2015-05-01

    The highest antiferromagnetic (AFM) temperature in Ce based compounds has been reported for CeScGe with TN=47 K , but its local or itinerant nature has not been deeply investigated yet. In order to shed more light into this unusually high ordering temperature we have investigated structural, magnetic, transport, and thermal properties of CeTi1 -xScxGe alloys within the range of stability of the CeScSi-type structure: 0.25 ≤x ≤1 . Along this concentration range, this strongly anisotropic system presents a complex magnetic phase diagram with a continuous modification of its magnetic behavior, from ferromagnetism for 0.25 ≤x ≤0.50 (with 7 K≤TC≤16 K ) to AFM for 0.60 ≤x ≤1 (with 19 K≤TN≤47 K ). The onset of the AFM phase is associated to a metamagnetic transition with a critical field increasing from Hcr=0 at x ≈0.55 to ≈6 T at x =1 , coincident with an increasing contribution of the first excited crystal electric field doublet. At a critical point xcr≈0.65 a second transition appears at TL≤TN . In contrast to observations in itinerant systems like CeRh2Si2 or CeRh3B2 , no evidences for significant hybridization of the 4 f electrons at large Sc contents were found. Therefore, the exceptionally large TN of CeScGe can be attributed to an increasing Ruderman-Kittel-Kasuya-Yosida interaction between Ce double layers as Sc content grows.

  19. Ag- and Cu-doped multifunctional bioactive nanostructured TiCaPCON films

    Science.gov (United States)

    Shtansky, D. V.; Batenina, I. V.; Kiryukhantsev-Korneev, Ph. V.; Sheveyko, A. N.; Kuptsov, K. A.; Zhitnyak, I. Y.; Anisimova, N. Yu.; Gloushankova, N. A.

    2013-11-01

    A key property of multicomponent bioactive nanostructured Ti(C,N)-based films doped with Ca, P, and O (TiCaPCON) that can be improved further is their antibacterial effect that should be achieved without compromising the implant bioactivity and biocompatibility. The present work is focused on the study of structure, chemical, mechanical, tribological, and biological properties of Ag- and Cu-doped TiCaPCON films. The films with Ag (0.4-4 at.%) and Cu (13 at.%) contents were obtained by simultaneous sputtering of a TiC0.5-Ca3(PO4)2 target and either an Ag or a Cu target. The film structure was studied using X-ray diffraction, transmission and scanning electron microscopy, energy dispersive X-ray spectroscopy, glow discharge optical emission spectroscopy, and Raman-shift and IR spectroscopy. The films were characterized in terms of their hardness, elastic modulus, dynamic impact resistance, friction coefficient and wear rate (both in air and normal saline), surface wettability, electrochemical behavior and Ag or Cu ion release in normal saline. Particular attention was paid to the influence of inorganic bactericides (Ag and Cu ions) on the bactericidal activity against unicellular yeast fungus Saccharomyces cerevisiae and gram-positive bacteria Lactobacillus acidophilus, as well as on the attachment, spreading, actin cytoskeleton organization, focal adhesions, and early stages of osteoblastic cell differentiation. The obtained results show that the Ag-doped films are more suitable for the protection of metallic surfaces against bacterial infection compared with their Cu-doped counterpart. In particular, an excellent combination of mechanical, tribological, and biological properties makes Ag-doped TiCaPCON film with 1.2 at.% of Ag very attractive material for bioengineering and modification of load-bearing metal implant surfaces.

  20. Ag- and Cu-doped multifunctional bioactive nanostructured TiCaPCON films

    Energy Technology Data Exchange (ETDEWEB)

    Shtansky, D.V., E-mail: shtansky@shs.misis.ru [National University of Science and Technology “MISIS”, Leninsky prospekt 4, Moscow 119049 (Russian Federation); Batenina, I.V.; Kiryukhantsev-Korneev, Ph.V.; Sheveyko, A.N.; Kuptsov, K.A. [National University of Science and Technology “MISIS”, Leninsky prospekt 4, Moscow 119049 (Russian Federation); Zhitnyak, I.Y.; Anisimova, N.Yu.; Gloushankova, N.A. [N.N. Blokhin Russian Cancer Research Center of RAMS, Kashirskoe shosse 24, Moscow 115478 (Russian Federation)

    2013-11-15

    A key property of multicomponent bioactive nanostructured Ti(C,N)-based films doped with Ca, P, and O (TiCaPCON) that can be improved further is their antibacterial effect that should be achieved without compromising the implant bioactivity and biocompatibility. The present work is focused on the study of structure, chemical, mechanical, tribological, and biological properties of Ag- and Cu-doped TiCaPCON films. The films with Ag (0.4–4 at.%) and Cu (13 at.%) contents were obtained by simultaneous sputtering of a TiC{sub 0.5}–Ca{sub 3}(PO{sub 4}){sub 2} target and either an Ag or a Cu target. The film structure was studied using X-ray diffraction, transmission and scanning electron microscopy, energy dispersive X-ray spectroscopy, glow discharge optical emission spectroscopy, and Raman-shift and IR spectroscopy. The films were characterized in terms of their hardness, elastic modulus, dynamic impact resistance, friction coefficient and wear rate (both in air and normal saline), surface wettability, electrochemical behavior and Ag or Cu ion release in normal saline. Particular attention was paid to the influence of inorganic bactericides (Ag and Cu ions) on the bactericidal activity against unicellular yeast fungus Saccharomyces cerevisiae and gram-positive bacteria Lactobacillus acidophilus, as well as on the attachment, spreading, actin cytoskeleton organization, focal adhesions, and early stages of osteoblastic cell differentiation. The obtained results show that the Ag-doped films are more suitable for the protection of metallic surfaces against bacterial infection compared with their Cu-doped counterpart. In particular, an excellent combination of mechanical, tribological, and biological properties makes Ag-doped TiCaPCON film with 1.2 at.% of Ag very attractive material for bioengineering and modification of load-bearing metal implant surfaces.

  1. Fluorescence properties of novel near-infrared phosphor CaSc{sub 2}O{sub 4}:Ce{sup 3+}, Nd{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Meng, J.X., E-mail: tmjx@jnu.edu.c [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); Zhang, F.J.; Peng, W.F.; Wan, W.J.; Xiao, Q.L.; Chen, Q.Q.; Cao, L.W. [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Wang, Z.L. [School of Chemistry and Biotechnology, Yunnan Nationalities University, Kunming 650031 (China)

    2010-10-15

    Research highlights: Novel near-infrared (NIR) phosphor, CaSc{sub 2}O{sub 4}:Ce{sup 3+}, Nd{sup 3+}, was synthesized. The phosphor gives strong Nd{sup 3+} characteristic NIR emissions in the range of 880-930 nm. The NIR emission intensity gets a 200 times enhancement benefited from the efficient energy transfer from a co-doped Ce{sup 3+}. The energy transfer mechanism was also briefly based on detailed investigation on spectrum and fluorescence lifetime. - Abstract: Novel near-infrared (NIR) phosphor, CaSc{sub 2}O{sub 4}:Ce{sup 3+}, Nd{sup 3+}, was synthesized by co-precipitation method followed by firing at 1300 {sup o}C in reduced atmosphere. When irradiated with blue light, the phosphor gives strong Nd{sup 3+} characteristic NIR emissions in the range of 880-930 nm. The NIR emission intensity gets a 200 times enhancement by co-doping of Ce{sup 3+}. Detailed investigation on spectrum and fluorescence lifetimes indicated the NIR luminescence enhancement is obtained from an energy transfer process. The process initiates with efficient absorption of blue light by Ce{sup 3+} ions via an allowed 4f-5d transition, follow by efficient energy transfer from Ce{sup 3+} to Nd{sup 3+}, and emitting strong Nd{sup 3+} characteristic fluorescence.

  2. 铁含量对CaTiO3-Fex光催化活性的影响%Effects of Fe content on photocatalytic activity of CaTiO3-Fex

    Institute of Scientific and Technical Information of China (English)

    韩冲; 杨合; 薛向欣

    2014-01-01

    利用XRD、SEM-EDS、FT-IR光谱、UV-Vis光谱等多种方法对CaTiO3-Fex进行表征,通过测定亚甲基蓝的光催化降解率来考察铁含量对CaTiO3-Fex光催化活性的影响。结果表明,当铁含量从0增加到4.745%时, CaTiO3-Fex的化学组成几乎保持不变。但是,随着铁含量的增加,CaTiO3-Fex的光吸收能力显著增强。亚甲基蓝在CaTiO3-Fex上的光催化降解遵循一级反应动力学。基于亚甲基蓝浓度的变化及其反应动力学,CaTiO3-Fe0.474%显示出最佳的光催化活性。在紫外-可见光光照3.0 h时,亚甲基蓝在CaTiO3-Fe0.474%上的光催化降解达到100%。亚甲基蓝在CaTiO3-Fe0.474%上光催化降解的表观速率常数(kobs)为1.33 h-1,是其在CaTiO3-Fe0上光催化降解的kobs的7倍。%CaTiO3-Fex was characterized by X-ray diffractometry, scanning electron microscopy equipped with an energy dispersive spectrometry system, Fourier transform infrared spectra, and UV-visible spectra. Effects of Fe content on photocatalytic activity of CaTiO3-Fex were investigated through measuring photocatalytic degradation rate of methylene blue. The results show that chemical compositions of CaTiO3-Fex remained unchanged with increasing Fe content from 0 to 4.745%. However, the light absorption ability of CaTiO3-Fex exhibited a significant increase with increasing Fe content. Photocatalytic degradation of methylene blue over CaTiO3-Fex followed the first-order reaction kinetics. Based on changes of the concentration of methylene blue and its degradation kinetics, CaTiO3-Fe0.474% has shown to have optimal photocatalytic activity. The degradation rate of methylene blue over CaTiO3-Fe0.474% was almost 100% under UV-visible light irradiation for 3.0 h. Thekobs of methylene blue over CaTiO3-Fe0.474% was 1.33 h-1 and was 7 times that over CaTiO3-Fe0.

  3. Formation of CaO·TiO2-MgO·Al2O3 dual phase inclusion in Ti stabilized stainless steel

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The formation of CaO.TiO2-MgO.Al2O3 dual phase inclusion in 321 stainless steel was investigated in the laboratory. The result indicated that the condition for the formation of CaO.TiO2-MgO.Al2O3 in 321 steel is [Ca]>0.001wt%, [Ti]>0.1wt%, and[Al]>0.01wt%. The mechanism is the following: Al2O3 inclusion turns into CaO-Al2O3 after Ca-Si wire is fed into the molten steel;[Mg] is then obtained by reducing MgO in slag or crucible wall by [Al] and [Ti]; finally CaO-Al2O3 inclusion is changed into CaO.TiO2-MgO-Al2O3 by the reaction with [Mg], [Ti], and [O] in the molten steel simultaneously.

  4. Probing the electronic structures and properties of neutral and anionic ScSi(n)((0,-1)) (n = 1-6) clusters using ccCA-TM and G4 theory.

    Science.gov (United States)

    Lu, Jun; Yang, Jucai; Kang, Yali; Ning, Hongmei

    2014-02-01

    The geometries, electronic structures and energies of small ScSi n species (n = 1-6) and their anions have been systematically investigated by means of the higher level of the ccCA-TM, G4, and G4(MP2) schemes. The global minima of these clusters have been presented. The global minima of neutral ScSi n (n = 1-6) and their anions are "substitutional structure" which is derived from Si n+1 by replacing a Si atom with a Sc atom. The adiabatic electron affinities for ScSi n have been estimated. Compared with limited experimental data, the average absolute deviations from experiment for ccCA-TM, G4, and G4(MP2) are 0.21 eV, 0.22 eV, and 0.25 eV, respectively. The dissociation energies of Sc atom from the lowest-energy structure of ScSi n clusters have been evaluated to examine relative stabilities. The electron affinities and dissociation energies predicted by ccCA-TM, G4, and G4(MP2) methods, especially for ccCA-TM and G4, differ little from each other. The agreement may indicate they are reliable.

  5. Structural and dielectric behavior of pulsed laser ablated Sr 0.6Ca 0.4TiO 3 thin film and asymmetric multilayer of SrTiO 3 and CaTiO 3

    Science.gov (United States)

    Chakraborty, Pradip; Choudhury, Palash Roy; Krupanidhi, S. B.

    2011-12-01

    Homogeneous thin films of Sr 0.6Ca 0.4TiO 3 (SCT40) and asymmetric multilayer of SrTiO 3 (STO) and CaTiO 3 (CTO) were fabricated on Pt/Ti/SiO 2/Si substrates by using pulsed laser deposition technique. The electrical behavior of films was observed within a temperature range of 153 K-373 K. A feeble dielectric peak of SCT40 thin film at 273 K is justified as paraelectric to antiferroelectric phase transition. Moreover, the Curie-Weiss temperature, determined from the ɛ'( T) data above the transition temperature is found to be negative. Using Landau theory, the negative Curie-Weiss temperature is interpreted in terms of an antiferroelectric transition. The asymmetric multilayer exhibits a broad dielectric peak at 273 K, and is attributed to interdiffusion at several interfaces of multilayer. The average dielectric constants for homogeneous Sr 0.6Ca 0.4TiO 3 films (˜650) and asymmetric multilayered films (˜350) at room temperature are recognized as a consequence of grain size effect. Small frequency dispersion in the real part of the dielectric constants and relatively low dielectric losses for both cases ensure high quality of the films applicable for next generation integrated devices.

  6. Mesoscopic-scale structure and dynamics near the morphotropic phase boundary of (1 -x ) PbTiO3-x BiScO3

    Science.gov (United States)

    Datta, K.; Richter, A.; Göbbels, M.; Neder, R. B.; Mihailova, B.

    2015-07-01

    A range of compelling information on the local structure and dynamics of the ferroelectric perovskite-type (ABO3) system (1 -x ) PbTiO3-x BiScO3 has been revealed through analyzing room-temperature x-ray pair distribution functions and temperature-dependent Raman scattering data for compositions ranging across the morphotropic phase boundary (MPB). Raman scattering data have provided exclusive evidence for distinct dynamical responses from the A-site Pb/Bi and the B-site Ti/Sc cations as a function of composition and temperature. Both pair distribution function and Raman scattering analyses indicate improved coherence between the A-site and B-site off-center displacements for x above the MPB composition. The distinguishable dynamical features were spotted between two sets of compositional range from which x =0.34 could be assigned as a critical composition of "local" MPB: the composition at which the pathway of mesoscopic-scale temperature-driven coupling and transformation processes changes. This differs from the previous reports based on the analysis of the average structure, suggesting the response function of a system may not necessarily follow the evolution of the average structure from which however the MPB has so far been ascribed for a particular system. The individual features of the cations revealed here will further help in understanding the structure-property correlations for similar ferroelectric solid solutions.

  7. Improved dielectric properties of CaCu3Ti4O12 films with a CaTiO3 interlayer on Pt/TiO2/SiO2/Si substrates prepared by pulsed laser deposition

    Science.gov (United States)

    Lee, Sung-Yun; Kim, Hui Eun; Jo, William; Kim, Young-Hwan; Yoo, Sang-Im

    2015-11-01

    We report the greatly improved dielectric properties of CaCu3Ti4O12 (CCTO) films with a 60 nm-thick CaTiO3 (CTO) interlayer on Pt/TiO2/SiO2/Si substrates. Both CCTO films and CTO interlayers were prepared by pulsed laser deposition (PLD). With increasing the thickness of CCTO from 200 nm to 1.3 μm, the dielectric constants ( ɛ r ) at 10 kHz in both CCTO single-layered and CCTO/CTO double-layered films increased from ˜260 to ˜6000 and from ˜630 to ˜3700, respectively. Compared with CCTO single-layered films, CCTO/CTO double-layered films irrespective of CCTO film thickness exhibited a remarkable decrease in their dielectric losses ( tanδ) (Poole-Frenkel conduction model. [Figure not available: see fulltext.

  8. Zn,Cd对CaTiO3:Pr3+的发光性质的影响%Effect of Zn,Cd on the Luminescent Properties of CaTiO3∶Pr3+

    Institute of Scientific and Technical Information of China (English)

    沈雷军; 赵增祺; 韩莉; 周永勃; 万作波; 张国斌; 张丹红

    2007-01-01

    采用高温固相反应合成CaTiO3∶Pr3+、Zn2TiO4、Ca0.7Zn0.3-xCdxTiO3∶Pr3+(x=0.01, 0.03, 0.05, 0.07, 0.09, 0.1)红色系列粉末状发光材料.经X射线衍射检测其结构,CaTiO3结构为正交晶系,其结果与JCPDS标准卡(42-423)相符.Zn2TiO4结构属立方晶系,结果与JCPDS标准卡(25-1164)一致.Ca0.7Zn0.3-xCdxTiO3∶Pr3+(x=0.01, 0.03, 0.05, 0.07, 0.09, 0.1)由两种物相组成,一种为CaTiO3,另一种为Zn2TiO4.检测了材料的激发光谱和发射光谱.发现,在CaTiO3∶Pr3+中加入适量Zn可形成Zn2TiO4相,使材料的激发光谱在324 nm附近的吸收增强.少量Cd可进入Zn2TiO4晶格,增强激发光谱在324 nm附近的吸收,同时提高发射光谱的强度;但过量的Cd 的加入会导致发射光谱强度下降.

  9. Photocatalytic hydrogen evolution over CaFe2O4/TiO2%CaFe2O4/TiO2光催化制氢性能

    Institute of Scientific and Technical Information of China (English)

    柯旭; 王晟; 皇甫彦; 刘福生; 胡海龙; 黄集森

    2016-01-01

    A series of p⁃n coupled CaFe2 O4/TiO2 photocatalysts were prepared. The structure and properties of CaFe2O4/TiO2 catalysts were characterized by X⁃ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet⁃visible diffuse reflectance spectrum (UV⁃Vis DRS) and electrochemical tests. The photocatalytic activities of CaFe2 O4/TiO2 catalysts were evaluated by photocatalytic hydrogen production under solar light. The effects of the amount of CaFe2 O4 , the concentration of HCHO and pH on hydrogen production were investigated. The mechanism of photocatalytic activity was discussed. Results showed that CaFe2 O4/TiO2 exhibited higher photocatalytic activity attributed to electrons transferring from CaFe2 O4 to TiO2 , resulted from the more negative conduction band potential of CaFe2 O4 than TiO2 and the inner electric field. 0�4%CaFe2 O4/TiO2 had the best performance among the various CaFe2 O4/TiO2 composite powders tested, with a hydrogen evolution rate of up to 0�989 mmol/( g · h ) in 2 h, and CaFe2 O4/TiO2 also exhibited the good stability with several recycling times.%本文制备了p n复合半导体光催化剂CaFe2 O4/TiO2,采用X线衍射仪( XRD)、扫描电子显微镜( SEM)、紫外可见漫反射光谱仪( UV Vis DRS)及电化学工作站对光催化剂的结构和性能进行表征。以模拟太阳光催化产氢速率评价p n复合半导体光催化剂CaFe2 O4/TiO2的光催化活性。探讨光催化剂中CaFe2 O4添加量、甲醛浓度、反应体系pH对光催化产氢性能的影响,并对光催化活性的提高进行了机制分析。结果表明:CaFe2 O4的导带比TiO2的导带更负,同时在CaFe2 O4/TiO2内存在内建电场,两者均促进了电子从CaFe2 O4向TiO2的迁移,增强了光催化活性,0�4%CaFe2O4/TiO2具有最高的光催化活性,2 h 内的产氢速率达到0�989 mmol/(g·h)。此外, CaFe2 O4/TiO2的稳定性较好,可多次循环使用。

  10. Improved persistent luminescence of CaTiO{sub 3}:Pr by fluorine substitution and thermochemical treatment

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Songhak, E-mail: songhak.yoon@empa.ch [Laboratory for Solid State Chemistry and Catalysis, Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Otal, Eugenio H.; Maegli, Alexandra E.; Karvonen, Lassi; Matam, Santhosh K. [Laboratory for Solid State Chemistry and Catalysis, Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Ebbinghaus, Stefan G. [Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Strasse 2, 06120 Halle/Saale (Germany); Walfort, Bernhard [LumiNova AG, Speicherstrasse 60A, CH-9053 Teufen (Switzerland); Hagemann, Hans [Department of Physical Chemistry, University of Geneva, Quai E. Ansermet 30, CH-1211 Geneva 4 (Switzerland); Pokrant, Simone [Laboratory for Solid State Chemistry and Catalysis, Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Weidenkaff, Anke [Laboratory for Solid State Chemistry and Catalysis, Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Institute for Materials Science, University of Stuttgart, Heisenbergstrasse 3, 70569 Stuttgart (Germany)

    2014-11-15

    Highlights: • Synthesis of fluorine-substituted CaTiO{sub 3}:Pr phosphors. • Rietveld refinement of CaTi(O,F){sub 3}:Pr phosphors. • Afterglow intensity improvement of ca. 450% compared to CaTiO{sub 3}:Pr. - Abstract: Fluorine-substituted CaTiO{sub 3}:Pr phosphors were prepared by a solid-state reaction. Rietveld refinements of powder X-ray diffraction patterns revealed that increasing fluorine-substitution leads to the gradual shrinkage of the unit-cell. Enhanced afterglow intensities were observed with fluorine-substitution. Furthermore, the effect of annealing atmosphere was investigated by thermochemical treatment in different atmospheres (Ar, air and NH{sub 3}). UV–Vis diffuse reflectance spectra and photoluminescence excitation spectra revealed that Pr{sup 4+} in the pristine CaTi(O,F){sub 3}:Pr phosphor was partially reduced to Pr{sup 3+} under NH{sub 3} flow leading to an intensity improvement of ca. 450% compared to CaTiO{sub 3}:Pr. The substantial improvement of afterglow intensity by fluorine substitution and annealing in NH{sub 3} is considered to be connected with the generation of oxygen vacancies and the partial reduction of Pr{sup 4+} to Pr{sup 3+}.

  11. Afterglow characteristics of CaTiO3: Pr3+ prepared by solar furnace

    Science.gov (United States)

    Katayama, Yumiko; Tanabe, Setsuhisa

    2011-05-01

    We have prepared polycrystalline CaTiO3: Pr3+ showing long-lasting phosphorescence by melting method using a solar furnace. Emission, excitation spectra, phosphorescence decay and thermoluminescence were compared with samples prepared by conventional solid-state reaction in conventional electric furnace (EF) at 1200 °C, 5 h in air. The color of the sample prepared by solar furnace (SF-AM) was dark brownish. After heat treatment at 800°C, 5h in air atmosphere, a decolorized sample (SF-HT) was obtained. All samples showed Pr3+:1D2 → 3H4 fluorescence at 613 nm and corresponding afterglow phosphorescence. The SF-AM and SF-HT showed much higher PLE intensity of Pr3+:3PJ bands in blue region than EF. CaTiO3:Pr3+ made by a solar furnace has a potential to be a red afterglow phosphor even under visible excitation.

  12. Domains and ferroelectric switching pathways in Ca3Ti2O7 from first principles

    Science.gov (United States)

    Nowadnick, Elizabeth A.; Fennie, Craig J.

    2016-09-01

    Hybrid improper ferroelectricity, where an electrical polarization can be induced via a trilinear coupling to two nonpolar structural distortions of different symmetries, recently was demonstrated experimentally in the n =2 Ruddlesden-Popper compound Ca3Ti2O7 . In this paper we use group theoretic methods and first-principles calculations to identify possible ferroelectric switching pathways in Ca3Ti2O7 . We identify low-energy paths that reverse the polarization direction by switching via an orthorhombic twin domain or via an antipolar structure. We also introduce a chemically intuitive set of local order parameters to give insight into how these paths are relevant to ferroelectric switching nucleated at domain walls. Our findings suggest that switching may proceed via more than one mechanism in this material.

  13. Fouling Resistant CA/PVA/TiO2 Imprinted Membranes for Selective Recognition and Separation Salicylic Acid from Waste Water

    Science.gov (United States)

    Yu, Xiaopeng; Mi, Xueyang; He, Zhihui; Meng, Minjia; Li, Hongji; Yan, Yongsheng

    2017-01-01

    Highly selective cellulose acetate (CA)/poly (vinyl alcohol) (PVA)/titanium dioxide (TiO2) imprinted membranes were synthesized by phase inversion and dip coating technique. The CA blend imprinted membrane was synthesized by phase inversion technique with CA as membrane matrix, polyethyleneimine (PEI) as the functional polymer, and the salicylic acid (SA) as the template molecule. The CA/PVA/TiO2 imprinted membranes were synthesized by dip coating of CA blend imprinted membrane in PVA and different concentration (0.05, 0.1, 0.2, 0.4 wt %) of TiO2 nanoparticles aqueous solution. The SEM analysis showed that the surface morphology of membrane was strongly influenced by the concentration of TiO2 nanoparticles. Compared with CA/PVA-TiO2(0.05, 0.1, 0.2%)-MIM, the CA/PVA-TiO2(0.4%)-MIM possessed higher membrane flux, kinetic equilibrium adsorption amount, binding capacity and better selectivity for SA. It was found that the pseudo-second-order kinetic model was studied to describe the kinetic of CA/PVA-TiO2(0.2%)-MIM judging by multiple regression analysis. Adsorption isotherm analysis indicated that the maximum adsorption capacity for SA were 24.43 mg g−1. Moreover, the selectivity coefficients of CA/PVA-TiO2 (0.2%)-MIM for SA relative to p-hydroxybenzoic acid (p-HB) and methyl salicylate (MS) were 3.87 and 3.55, respectively. PMID:28184369

  14. Alpha clustering in Ti isotopes: 40,44,48Ca + α resonant scattering

    Directory of Open Access Journals (Sweden)

    Bailey Sam

    2016-01-01

    Full Text Available Measurements were made of the 4He(40,44,48Ca,α resonant scattering reactions at 180° and up to Ec.m. ~ 11.5MeV, using the Thick Target Inverse Kinematics technique. These measurements are discussed, with a focus on assessing their usefulness for investigating α-clustering in medium mass 44,48,52Ti nuclei.

  15. Impact of symmetry on the ferroelectric properties of CaTiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Biegalski, Michael D.; Qiao, Liang [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Gu, Yijia; Chen, Long-Qing [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16801 (United States); Mehta, Apurva [Stanford Synchrotron Lightsource SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); He, Qian; Borisevich, Albina [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Takamura, Yayoi, E-mail: ytakamura@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California Davis, Davis, California 95616 (United States)

    2015-04-20

    Epitaxial strain is a powerful tool to induce functional properties such as ferroelectricity in thin films of materials that do not possess ferroelectricity in bulk form. In this work, a ferroelectric state was stabilized in thin films of the incipient ferroelectric, CaTiO{sub 3}, through the careful control of the biaxial strain state and TiO{sub 6} octahedral rotations. Detailed structural characterization was carried out by synchrotron x-ray diffraction and scanning transmission electron microscopy. CaTiO{sub 3} films grown on La{sub 0.18}Sr{sub 0.82}Al{sub 0.59}Ta{sub 0.41}O{sub 3} (LSAT) and NdGaO{sub 3} (NGO) substrates experienced a 1.1% biaxial strain state but differed in their octahedral tilt structures. A suppression of the out-of-plane rotations of the TiO{sub 6} octahedral in films grown on LSAT substrates resulted in a robust ferroelectric I4 mm phase with remnant polarization ∼5 μC/cm{sup 2} at 10 K and T{sub c} near 140 K. In contrast, films grown on NGO substrates with significant octahedral tilting showed reduced polarization and T{sub c}. These results highlight the key role played by symmetry in controlling the ferroelectric properties of perovskite oxide thin films.

  16. Crystal field analysis of the absorption spectra and electron phonon interaction in Ca3Sc2Ge3O12:Ni2+

    Science.gov (United States)

    Brik, M. G.

    2006-04-01

    Exchange charge model of crystal field [B.Z. Malkin, in: A.A. Kaplyanskii, B.M. Macfarlane (Eds.), Spectroscopy of Solids Containing Rare-earth Ions, North-Holland, Amsterdam, 1987, pp. 33 50.] was used to analyze the energy level schemes of Ni2+ ion at both possible positions (octahedral and tetrahedral) in Ca3Sc2Ge3O12. The crystal field parameters were calculated from the crystal structure data; the crystal field Hamiltonian was diagonalised in the complete basis consisting of 25 wave functions of all LS terms of the Ni2+ ion. Results of calculations are in a good agreement with experimental data. From the experimental spectra available in the literature, the Huang Rhys parameter S=3.5 and effective phonon energy ℏω=200cm were evaluated for the octahedral Ni2+ ion.

  17. Spectral Properties and Energy Transfer between Ce(3+) and Yb(3+) in the Ca3Sc2Si3O12 Host: Is It an Electron Transfer Mechanism?

    Science.gov (United States)

    Zhou, Lei; Tanner, Peter A; Ning, Lixin; Zhou, Weijie; Liang, Hongbin; Zheng, Lirong

    2016-07-21

    The downshifting from Ce(3+) blue emission to Yb(3+) near-infrared emission has been studied in the garnet host Ca2.8-2xCe0.1YbxNa0.1+xSc2Si3O12 (x = 0-0.36). The downshifting does not involve quantum cutting, but one incident blue photon is transferred from Ce(3+) to Yb(3+) with an energy transfer efficiency up to 90% when x = 0.36 for the Yb(3+) dopant ion. For x ≤ 0.15, a multiphonon-assisted electric dipole-electric quadrupole mechanism of energy transfer dominates, while for the highest concentration of Yb(3+) employed, the electron transfer mechanism is confirmed. A temperature-dependent increase of the Ce(3+) → Yb(3+) energy transfer rate does not exclusively indicate the electron transfer mechanism. The application of the material to solar energy conversion is indicated.

  18. Synthesis of CaTiO3 from calcium titanyl oxalate hexahydrate (CTO) as precursor employing microwave heating technique

    Indian Academy of Sciences (India)

    B M Patil; R S Srinivasa; S R Dharwadkar

    2007-06-01

    Calcium titanate, CaTiO3, an important microwave dielectric material and one of major phases in synroc (synthetic rock), a titanate ceramic with potential application for fixation of high level nuclear waste was synthesized from calcium titanyl oxalate [CaTiO (C2O4)2.6H2O] (CTO) by employing microwave heating technique. CTO heated in microwave heating system in air at 500°C for 1 h gave a perovskite, CaTiO3. The product obtained by heating of CTO in the same system at 700°C for the same duration was however, much more crystalline. CaTiO3 obtained by the present method was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET surface area measurement.

  19. Anomalous Optical and Electronic Properties of CaTiO3 Perovskites

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With the help of the first-principles full potential linearized augmented plane wave method, absorption coefficients, reflectivity, dielectric behavior and electronic properties, including electronic energy bands, density of states and charge density distributions, are studied for the tetragonal and cubic CaTiO3. By considering the thermal expansion effects, an approximate method is proposed for the study of the stability of ground state and a tendency of phase transition, based on the minimum free energy principle. Subsequently, numerical calculations are carried out by using the first-principles perturbation method. We demonstrate that the high-temperature phase is cubic. It is shown that optical spectra in tetragonal phase exhibit single-peak feature and differ from multi-peak character in cubic. We find that strong orbital hybridization results in the co-valent bonds between Ti 3d and O 2p electrons and forms two-type dipoles (Ti-O1 and Ti-O2) in tetragonal, while the Ti-O dipoles are identical in cubic. It is argued that crystal structure determines the dipole distributions and leads to some electron states among which the dipole-dipole transition forbidden is a key, causing such anomalous optical phenomena with the insulator characteristics. The predicted charge density distribution and the tendency of phase transition from tetragonal to cubic are in good agreement with experimental observations.

  20. Characterisation of a duplex TiO2/CaP coating on Ti6Al4V for hard tissue replacement.

    Science.gov (United States)

    Ng, Boon Sing; Annergren, Ingegerd; Soutar, Andrew M; Khor, K A; Jarfors, Anders E W

    2005-04-01

    An initial TiO(2) coating was applied on Ti6Al4V by electrochemical anodisation in two dissimilar electrolytes. The secondary calcium phosphate (CaP) coating was subsequently applied by immersing the substrates in a simulated body fluid (SBF) with three times concentration (SBFx3), mimicking biomineralisation of biological bone. Electrochemical impedance spectroscopy and potentiodynamic polarisation assessments in SBF revealed that the anodic TiO(2) layer is compact, exhibiting up to four-folds improvement in in vitro corrosion resistance over unanodised Ti6Al4V. X-ray photoelectron spectroscopy analysis indicates that the anodic Ti oxide is thicker than air-formed ones with a mixture of TiO(2-x) compound between the TiO(2)/Ti interfaces. The morphology of the dense CaP film formed, when observed using scanning electron microscopy, is made up of linked globules 0.1-0.5microm in diameter without observable delamination. Fourier transform infrared spectrometry with an attenuated total internal reflection analysis revealed that this film is an amorphous/poorly crystallised calcium-deficient-carbonated CaP system. The calculated Ca:P ratios of all samples (1.14-1.28) are lower than stoichiometric hydroxyapatite (1.67). These results show that a duplex coating consisting of (1) a compact TiO(2) with enhanced in vitro corrosion resistance and (2) bone-like apatite coating can be applied on Ti6Al4V by anodisation and subsequent immersion in SBF.

  1. Ca(Ti,Si)O3 Diamond Inclusions Crystallized From Carbonate Melts in the Transition Zone: Experimental Constraints

    Science.gov (United States)

    Armstrong, L. S.; Walter, M. J.; Keshav, S.; Bulanova, G.; Pickles, J.; Lord, O. T.; Lennie, A.

    2007-12-01

    Composite diamond inclusions consisting of coexisting endmember CaSiO3 and CaTiO3 are rare but occur in diamond populations from Juina, Brazil1-2. Phase relations show that above ~9 GPa (at 1500 K) a perovskite-structured solid solution exists between these endmembers, while at lower pressures intermediate compositions produce coexisting CaTiO3-perovskite and CaSiO3 in the walstromite structure3. Inclusions with `perovskite' stoichiometry are commonly interpreted as fragments of solid mantle from the transition zone or lower mantle4-6. Here we report on two composite diamond inclusions from Juina kimberlite, and can effectively eliminate a subsolidus origin on the basis of experimental mineral phase relations. Instead, based on new melting experiments we find that the inclusions most likely crystallized directly from Ca-rich carbonate melts. Like other workers1-2 we interpret the composite inclusions as exsolution products of a high-pressure Ca(Ti,Si)O3 perovskite stable in the transition zone. Our bulk inclusion compositions are estimated to contain 50- 65 mol% CaTiO3, and are remarkably low in MgSiO3 component at less than 0.2 mol%. Experiments have shown that in peridotite or eclogite lithologies, Ca-rich perovskite in equilibrium with an MgSiO3-phase (majorite or Mg-perovskite) have about 3 to 7 mol% MgSiO37-8. Here we report on new subsolidus laser-heated diamond anvil cell experiments at 20-50 GPa in the ternary system CaSiO3-CaTiO3-MgSiO3 that bracket the CaTi-rich limb of the solvus between Ca- and Mg-rich perovskites. All experiments were made at 2000 (±200) K for 45-75 min, and were analysed using synchrotron micro-focus X-ray diffraction. We find that the solubility of MgSiO3 in CaTi-perovskite solid solutions increases significantly with increasing CaTiO3 component. Thus, Ti-rich calcium perovskite in peridotite or eclogite lithologies should have very high, not exceptionally low, MgSiO3 component. Accordingly, a subsolidus paragenesis is unlikely for

  2. Large Electric-Field Modulation of Magnetic Properties in Fe Films on BiScO3-PbTiO3 Ceramics

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2010-01-01

    Full Text Available Based on the magneto-optical Kerr effect, we report the electric-field modulation of the magnetic properties in Fe/BiScO3-PbTiO3 (BSPT film-on-ceramic substrate structure. The Fe films are directly grown on the fully-poled BSPT ceramic substrates by magnetron sputtering. An electric field applied parallel to the prepolarization direction of the piezoelectric BSPT can induce a reversible increase in the coercive field Hc of about 30%, whereas an electric field antiparallel to the prepolarization direction can cause a persistent, tremendous decrease (as large as 97% in Hc, and a small reversal electric field can resume it back. The strain induced by the inverse piezoelectric effect is the primary mechanism behind. This large modulation of the coercive field by the electric field could inspire further exploration of electric-field-controlled magnetic switching in multiferroic heterostructures.

  3. Fe-moment instability in Ti{sub 1-x}Sc{sub x}Fe{sub 2} Laves-phase compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ouladdiaf, B. [Institut Laue-Langevin, BP 156, 38042 GRENOBLE Cedex 09 (France); Deportes, J. [Lab. Louis Neel, CNRS, BP 166, 38042 GRENOBLE Cedex 09 (France); Saoudi, M. [Centre Universitaire de Guelma, GUELMA 24 000 (Algeria)

    2002-07-01

    The magnetic properties of the pseudo-binary Laves-phase compounds Ti{sub 1-x}Sc{sub x}Fe{sub 2} were investigated by means of magnetisation and high-resolution powder neutron diffraction techniques. For x<0.2 a transition from an antiferromagnetic state to a canted one with a ferromagnetic component in the basal plane is observed, while for 0.2

  4. THE EFFECT OF DIFFERENT POLYMORPHS TiO2 RAW MATERIALS ON THE DIELECTRIC PROPERTIES AND MICROSTRUCTURE IN CaCu3Ti4O12 CERAMICS

    Directory of Open Access Journals (Sweden)

    Hao W.

    2013-09-01

    Full Text Available CaCu3Ti4O12 ceramics with different polymorphs of TiO2 as starting materials were prepared by the conventional solid-state reaction technique. Their crystalline structure, microstructure and dielectric properties were systematically investigated. It has been found that all of the ceramic specimens prepared in the present study have a good polycrystalline structure, and no secondary phase is been found by XRD. However, large differences in dielectric properties and microstructure are observed in them: 1 the characteristic frequency of dielectric relaxation around 1 MHz in the CCTO ceramics prepared with rutile TiO2 is much lower than that in those ceramics prepared with anatase TiO2; 2 no matter dielectric properties or microstructure, the CCTO ceramics prepared with rutile TiO2 are more sensitive to the sintering temperature than those ceramics prepared with anatase TiO2.

  5. Rare earth doped CaCu_3Ti_4O_(12) electronic ceramics for high frequency applications

    Institute of Scientific and Technical Information of China (English)

    慕春红; 张怀武; 刘颖力; 宋远强; 刘鹏

    2010-01-01

    Ca1-xRxCu3Ti4O12(R=La,Y,Gd;x=0,0.1,0.2,0.3) electronic ceramics were fabricated by conventional solid-state reaction method.The microstructure and dielectric properties as well as impedance behavior were carefully investigated.XRD results showed that the secondary phases with the general formula R2Ti2O7 existed at grain boundaries of rare earth doped ceramics,which inhibited abnormal grain growth.The dielectric constant decreased from 4×105 in pure CaCu3Ti4O12(CCTO) ceramics to 2×103 with rare earth doping....

  6. Experimental results for studies of the 40Ca(α,γ)44Ti reaction rates

    Science.gov (United States)

    Robertson, Daniel; Becker, Hans-Werner; Bowers, Matt; Collon, Philippe; Goerres, Joachim; Lu, Wenting; Schmitt, Chris; Wiescher, Michael

    2011-10-01

    Observational studies of galactic γ emitters such as 44Ti have highlighted their use in nucleosynthesis studies of massive stars in their late stage stellar evolution and final explosive demise in core collapse supernova events. Models used in the simulation of such γ emitters rely heavily upon reliable reaction rates for both the creation and annihilation of these isotopes over large temperature ranges. The production of 44Ti mainly through the 40Ca(α,γ)44Ti reaction is thought to take place primarily in the α-rich freeze out phase of a core collapse supernova. However, current supernova models predict lower 44Ti to 56Ni ratios than observed, creating a need for more information about its production mechanism. A number of previous studies include prompt γ-ray measurements, recoil mass separator experiments and the use of AMS, all giving greatly different reaction rates. Aiding in the refinement of these needed rates, the results of experiments at the DTL, Bochum and NSL, Notre Dame will be presented against the backdrop of these previous measurements. Work supported by grant # 0758100 and # 0822648.

  7. Critical thickness of high structural quality SrTiO3 films grown on orthorhombic (101) DyScO3

    Energy Technology Data Exchange (ETDEWEB)

    Hawley, Marilyn E [Los Alamos National Laboratory; Biegalski, Michael D [ORNL; Schlom, Darrell G [CORNELL U.

    2008-01-01

    Strained epitaxial SrTiO{sub 3} films were grown on orthorhombic (101) DyScO{sub 3} substrates by reactive molecular-beam epitaxy. The epitaxy of this substrate/film combination is cube on cube with a pseudocubic out-of-plane (001) orientation. The strain state and structural perfection of films with thicknesses ranging from 50 to 1000 {angstrom} were examined using x-ray scattering. The critical thickness at which misfit dislocations was introduced was between 350 and 500 {angstrom}. These films have the narrowest rocking curves (full width at half maximum) ever reported for any heteroepitaxial oxide film (0.0018{sup o}). Only a modest amount of relaxation is seen in films exceeding the critical thicknesses even after postdeposition annealing at 700{sup o}C in 1 atm of oxygen. The dependence of strain relaxation on crystallographic direction is attributed to the anisotropy of the substrate. These SrTiO{sub 3} films show structural quality more typical of semiconductors such as GaAs and silicon than perovskite materials; their structural relaxation behavior also shows similarity to that of compound semiconductor films.

  8. PHOTOCATALYTIC ACTIVITY OF TiO2 NANO SUPPORTED ON MEMBRANE CELLULOSE ACETATE/NATA DE COCO (CA/NDC IN PHOTODEGRADATION OF METHYLENE BLUE

    Directory of Open Access Journals (Sweden)

    Roro Ernia Prawithasari

    2015-12-01

    Full Text Available Study of synthesis and effectiveness of membrane catalyst of cellulose acetate/nata de coco-TiO2 nano (CA/NDC-TiO2 nano in photodegradation of methylene blue in batch system has been investigated. TiO2nanoparticles were synthesized by hydrothermal method followed by calcination at 450oC. Scanning Electron Microscopy (SEM images indicate nano TiO2 has been successfully synthesized with average particle diameter as 88,63±4,37 nm. X-ray diffraction pattern (XRD of nano TiO2 shows some characteristic peaks of anatase TiO2 were still existed. Membrane photocatalyst of CA/NDC- nano TiO2 was prepared via phase inversion method by mixing TiO2 nanoparticles with CA casting solution. Thermogravimetric analysis shows three decomposition steps of CA/NDC-nano membrane as well as CA/NDC membrane. Photodegradation of methylene blue was conducted with nano-TiO2 particles and CA/NDC-TiO2 membrane for 50 minutes in batch system. The absorbance changes were measured by spectrophotometer at wavelength of 664.6 nm. The result shows the photodegradation rections tended to follow second order reaction. According to the rate constant value, k, the photocatalytic effectivity using CA-NDC/nano TiO2 membrane and nano TiO2photocatalysts in metilen blue photodegradation, statistically were not significantly different.

  9. New Measurements of the Astrophysically Important ^44Ti Radionuclide Through the ^40Ca(α,γ)^44Ti Reaction

    Science.gov (United States)

    Robertson, Daniel; Becker, Hans-Werner; Collon, Philippe; Goerres, Joachim; Wiescher, Michael

    2010-11-01

    The relatively short-lived radionuclide ^44Ti (t1/2=58.9 ± 0.3 yrs), is of considerable importance in the study of nucleosynthesis in explosive stellar environments. It's production predominantly through the ^40Ca(α,γ)^44Ti reaction, takes place during α-rich freeze-out, in the inner most layers of a core-collapse supernova. A number of experimental studies have been previously performed to determine the stellar reaction rate. These studies included prompt γ-ray measurements from in-beam experiments, atom counting techniques utilizing accelerator mass spectrometry (AMS) and multi energy step measurements at the DRAGON recoil mass separator. The resulting calculated reaction rates show drastic disagreement. New results from experiments at the DTL, Bochum and NSL, Notre Dame, used both gamma spectroscopy and AMS techniques to measure the reaction, and investigate the discrepancies in both the experimental and predicted results. Final results of the experiments and their impact on the reaction rate will be discussed.

  10. CaCu2.7Ti4O12介电性能和J-E特征%Dielectric Properties and J-E Behavior of CaCu2.7Ti4O12 Ceramics

    Institute of Scientific and Technical Information of China (English)

    吴爽爽; 莫兴婵; 韦成峰; 韦小圆; 朱文凤; 覃远东; 刘来君

    2013-01-01

    Cu-deficient CaCu3 Ti4 O12 (CaCu2.7Ti4O12) ceramics were prepared by a traditional solid-state reaction method.The influence of holding time on the phase structure,microstructure,dielectric and J-E nonlinear characteristics was investigated.The results indicate that prolonging the holding time can decrease the dielectric loss of lowand medium-frequency and enhances greatly dielectric constant of CaCu2.7 Ti4 O12 ceramics,as well as reduces the breakdown voltage and the nonlinearity coefficient,which can be applied in semiconductor circuits as varistors.The characteristic of J-E nonlinear and change of electrical properties were explained by Sehottky thermion launch model.It is considered that the width of depletion layer plays an important role in electrical properties.The CaCu2.7 Ti4 O12 ceramics with holding time for 30 h is expected to apply in semiconductor circuit as a low voltage varistor.%采用传统的固相反应法制备了Cu欠量的CaCu3 Ti4 O12 (CaCu2.7Ti4 O12)陶瓷,研究了不同烧结时间对CaCu2.7Ti4O12相结构、显微形貌、介电性能和J-E非线性特征的影响.结果表明,延长保温时间降低了CaCu2.7-Ti4 O12陶瓷的中低频介电损耗和击穿场强并且显著提高了其介电常数.采用肖特基热电子发射模型对其非线性特征和电学性能的变化机理进行了分析,认为耗尽层宽度是影响电学性能的主要因素.保温30 h的CaCu2.7Ti4 O12陶瓷有望作为低压压敏电阻应用于半导体电路中.

  11. Projectile influence on production cross section for ^48Ca-, ^50Ti-, and ^54Cr- induced fusion-evaporation reactions

    Science.gov (United States)

    Mayorov, D. A.; Werke, T. A.; Alfonso, M. C.; Bennett, M. E.; Folden, C. M., III

    2013-04-01

    Evaporation residue excitation functions for ^48Ca, ^50Ti + ^159Tb and ^48Ca, ^54Cr + ^162 Dy were measured at Texas A&M University using the vacuum spectrometer MARS. The produced residues are weakly deformed nuclei near the N = 126 shell closure. However, the production cross sections are insensitive to the associated shell stabilization to the fission barrier, an observation previously reported in literature. The ratio of maximum production cross sections between the ^48Ca/^50Ti and ^48Ca/^54Cr reactions is 47 and 7100, respectively. These substantial differences can be reproduced in theoretical calculations by inclusion of collective enhancements during de-excitation of the compound nucleus. The competition between quasifission and complete fusion further contributes to the observed separation in the excitation functions. Model-dependent estimates of the compound nucleus formation probability, PCN, yield ratios of PCN(^48Ca + ^159 Tb) / PCN(^50Ti + ^159 Tb) 2.5 and PCN(^48Ca + ^162Dy) / PCN(^54Cr + ^162Dy) 5. Heavy-ion fusion reactions with ^48Ca, ^50Ti, and ^54Cr projectiles are of interest due to modern-day efforts to synthesize superheavy elements 119 and 120 in warm fusion reactions with projectiles having Z 20.

  12. Sol–gel synthesis and photoluminescence of CaTi1–ZrO3 : Pr3+ phosphors

    Indian Academy of Sciences (India)

    Lixia Lin; Bing Yan

    2010-02-01

    CaTi1–ZrO3 : Pr3+ phosphors have been synthesized by sol–gel and solid state methods, with = 1/300, 2/300, 3/300, 4/300, 5/300, 6/300, 7/300, respectively. Powder X-ray diffraction (XRD), UV-visible absorption spectra, photoluminescent spectra (PL), and scanning electron microscopy (SEM) images are used to characterize the powder samples. The inverse absorption at 610 nm appearing in the UV-visible absorption spectra is due to the ${}^{1}D_{2} \\rightarrow {}^{3}H_{4}$ characteristic emission of Pr3+. Changes in the emission spectra at 610 nm were agreed with those in UV-visible absorption spectra. The strongest red excitation obtained from CaTi1–ZrO3 : Pr3+ ( = 4/300) and CaTi1–ZrO3 : Pr3+ ( = 5/300) possesses the strongest emission at 610 nm, similar to the intensities of Ca(Ti1–Zr)O3 : Pr3+ ( = 3/300, 4/300, 6/300), which may be corresponded to the cell parameters of CaTi1–ZrO3 : Pr3+.

  13. Natural CaO-TiO2-SiO2 based ceramics

    Directory of Open Access Journals (Sweden)

    Jelena Pantić

    2011-06-01

    Full Text Available Lešnica river deposits consist of a large number of minerals of different grain sizes including sphene. Since it is very difficult to obtain pure monophase titanite by different synthetic routes (sol-gel, coprecipitation, combustion, spray pyrolysis and hydrothermal method, the aim of this work was to study the structure of the sphene from the Lešnica river deposits and possibility of using it as a natural precursor for CaO-TiO2-SiO2 based ceramics. The sphene from Lešnica was analyzed by different methods: tristimulus colorimetry, infrared spectroscopy, electron microprobe and X-ray single crystal diffraction. It was confirmed that Al, Fe, Mn and P are present in the sphene structure and proposed that corresponding structural formula could be: (Ca2+1.008 Mn2+0.0021.010(Ti4+0.901 Fe3+0.033 Al3+0.060 P5+0.0010.995 Si4+1.024 O2-5.

  14. Enhanced dielectric and ferroelectric characteristics in Ca-modified BaTiO3 ceramics

    Directory of Open Access Journals (Sweden)

    Xiao Na Zhu

    2013-08-01

    Full Text Available Synergic modification of BaTiO3 ceramics was investigated by Ca-substitution, and the superior dielectric and ferroelectric properties were determined together with the structure evolution. X-ray diffraction (XRD analysis demonstrated a large solubility limit above x = 0.25 in Ba1−xCaxTiO3 solid solution where the fine grain structure was observed with increasing x. Room temperature dielectric constant as high as 1655 was achieved in the present ceramics together with the significantly reduced dielectric loss of 0.013 (x = 0.20 at 100 kHz, where the Curie temperature kept almost a constant while other two transition temperatures decreased continuously with increasing x. More importantly, the remanent polarization Pr and dielectric strength Eb were significantly enhanced by Ca-substitution, and the best Pr (11.34 μC/cm2 and the highest dielectric strength Eb (75 kV/cm were acquired at x = 0.25. The present ceramics should be very desirable for the applications such as high density energy storage devices.

  15. A new (Ba, Ca) (Ti, Zr)O3 based multiferroic composite with large magnetoelectric effect

    Science.gov (United States)

    Naveed-Ul-Haq, M.; Shvartsman, Vladimir V.; Salamon, Soma; Wende, Heiko; Trivedi, Harsh; Mumtaz, Arif; Lupascu, Doru C.

    2016-08-01

    The lead-free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3 - 0.5(Ba0.7Ca0.3)TiO3 (BCZT) is a promising component for multifunctional multiferroics due to its excellent room temperature piezoelectric properties. Having a composition close to the polymorphic phase boundary between the orthorhombic and tetragonal phases, it deserves a case study for analysis of its potential for modern electronics applications. To obtain magnetoelectric coupling, the piezoelectric phase needs to be combined with a suitable magnetostrictive phase. In the current article, we report on the synthesis, dielectric, magnetic, and magnetoelectric characterization of a new magnetoelectric multiferroic composite consisting of BCZT as a piezoelectric phase and CoFe2O4 (CFO) as the magnetostrictive phase. We found that this material is multiferroic at room temperature and manifests a magnetoelectric effect larger than that of BaTiO3 -CoFe2O4 bulk composites with similar content of the ferrite phase.

  16. A new (Ba, Ca) (Ti, Zr)O3 based multiferroic composite with large magnetoelectric effect

    Science.gov (United States)

    Naveed-Ul-Haq, M.; Shvartsman, Vladimir V.; Salamon, Soma; Wende, Heiko; Trivedi, Harsh; Mumtaz, Arif; Lupascu, Doru C.

    2016-01-01

    The lead-free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3 − 0.5(Ba0.7Ca0.3)TiO3 (BCZT) is a promising component for multifunctional multiferroics due to its excellent room temperature piezoelectric properties. Having a composition close to the polymorphic phase boundary between the orthorhombic and tetragonal phases, it deserves a case study for analysis of its potential for modern electronics applications. To obtain magnetoelectric coupling, the piezoelectric phase needs to be combined with a suitable magnetostrictive phase. In the current article, we report on the synthesis, dielectric, magnetic, and magnetoelectric characterization of a new magnetoelectric multiferroic composite consisting of BCZT as a piezoelectric phase and CoFe2O4 (CFO) as the magnetostrictive phase. We found that this material is multiferroic at room temperature and manifests a magnetoelectric effect larger than that of BaTiO3 −CoFe2O4 bulk composites with similar content of the ferrite phase. PMID:27555563

  17. Elastic softening mode change in Y{sub 1-x}Ca{sub x}TiO{sub 3} by Ca-doping

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Takashi [Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan)]. E-mail: tsuzuki@hiroshima-u.ac.jp; Morita, Shinya [Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan); Higaki, Haruhiro [Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan); Ishii, Isao [Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan); Takemura, Masaki [Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan); Iga, Fumitoshi [Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan); Takabatake, Toshiro [Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan); Tsubota, Masami [JAERI/SPring-8, Hyogo 679-5198 (Japan)

    2006-05-01

    We measured various elastic moduli of single-crystalline Y{sub 1-x}Ca{sub x}TiO{sub 3} (x=0, and 0.2) as a function of temperature by means of an ultrasonic technique. Remarkable elastic softening has been found in transverse C{sub 44} for the sample with x=0 around 60K, indicating structural symmetry lowering corresponding to the e{sub yz} strain. In contrast, the sample with x=0.2 shows large softening in C{sub 55} in response to e{sub zx} around 130K. These results reveal that Y{sub 1-x}Ca{sub x}TiO{sub 3} (x=0, and 0.2) undergo a structural transition and the crystal symmetry of the low temperature phase is changed by Ca-doping.

  18. Enhanced Osteogenic Activity of TiO2 Nanorod Films with Microscaled Distribution of Zn-CaP.

    Science.gov (United States)

    He, Meng; Chen, Xiaoyi; Cheng, Kui; Weng, Wenjian; Wang, Huiming

    2016-03-23

    The topography at the micro-/nanoscale level and bioactive composition of material surfaces have been thought to play vital roles in their interactions with cells. However, it is still a challenge to further modify special topography with biodegradable composition or vice versa. In this study, TiO2 nanorod films covered with microscale-distributed Zn-containing calcium phosphate (Zn-CaP) were prepared, trying to create a micro-/nanoscale topography and Zn(2+) release capability. MC3T3-E1 cells cultured on TiO2 nanorod film with sparsely distributed Zn-CaP (TiO2/S-ZCP) had significantly higher biological responses than those on the films with densely distributed Zn-CaP (TiO2/D-ZCP) and fully covered Zn-CaP (F-ZCP). TiO2/S-ZCP film was demonstrated to facilitate osteogenic differentiation much more strongly than F-ZCP and TiO2/D-ZCP films based on evaluations of ALP, related gene expressions, and extracellular matrix mineralization. The higher osteogenic differentiation on TiO2/S-ZCP film is ascribed to the micro-/nanoscale topography from Zn-CaP coverage promoting cell adhesion and filopodia extension, and inducing differentiation-orientation in the initial stage. And consequently Zn(2+) release results in enhancement of differentiation. Therefore, we believe that better organization of the micro-/nanotopography and bioactive ion release on the surface would be a promising way to enhance osteogenic activity for orthopedic and dental implants.

  19. Synthesis condition and structural/luminescent properties of CaTiO{sub 3}:Eu{sup 3+} red phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Orihashi, Takuya; Adachi, Sadao, E-mail: adachi@el.gunma-u.ac.jp

    2015-10-15

    Eu{sup 3+}-activated CaTiO{sub 3} red phosphor is synthesized by the solid-state reaction method and its structural and optical properties are investigated using X-ray diffraction analysis, photoluminescence (PL) analysis, PL excitation (PLE) spectroscopy, and PL lifetime measurements. The effects of calcination condition (temperature, duration, and Eu dopant concentration) on the structural and Eu{sup 3+} emission properties are studied in detail. Temperature dependences of the PL intensity and decay time at T = 20–300 K are measured and analyzed on the basis of the thermal quenching model. It has been found that CaTiO{sub 3} can be formed at activation energy of ∼0.4 eV, which is considerably lower than the thermal activation energy (∼1.0 eV) of Eu{sup 3+} in the CaTiO{sub 3} host. Thermal quenching of the Eu{sup 3+} emission has also been observed to occur at an energy of ∼0.25 eV, determined from the temperature-dependent luminescence intensity and decay time analyses. The schematic energy-level diagram for Eu{sup 3+} in the CaTiO{sub 3} host is also proposed for the sake of a better understanding of the PL and PLE processes in this phosphor system. - Highlights: • Optimization was made for synthesizing CaTiO{sub 3}:Eu{sup 3+} red phosphor using the solid-state reaction method. • Eu{sup 3+} concentration was optimized to obtain high efficient red phosphor. • Temperature-dependent Eu{sup 3+} emission properties were measured and analyzed in detail. • An energy-level scheme for Eu{sup 3+} ion in CaTiO{sub 3} was proposed.

  20. Influence of titanium precursor on photoluminescent emission of micro-cube-shaped CaTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Mazzo, Tatiana Martelli, E-mail: tatimazzo@gmail.com [Departamento de Ciências do Mar, Universidade Federal de São Paulo, Avenida Almameda Saldanha da Gama, 89, Ponta da Praia, CEP 11030-400 Santos, SP (Brazil); Santilli do Nascimento Libanori, Gabriela [Departamento de Ciências do Mar, Universidade Federal de São Paulo, Avenida Almameda Saldanha da Gama, 89, Ponta da Praia, CEP 11030-400 Santos, SP (Brazil); Moreira, Mario Lucio [Instituto de Física e Matemática, Universidade Federal de Pelotas, P.O. Box 354, Campus do Capão do Leão, 96001-970 Pelotas, RS (Brazil); Avansi Jr, Waldir [Departamento de Física, Universidade Federal de São Carlos, Jardim Guanabara, 13565-905 São Carlos, SP (Brazil); Mastelaro, Valmor Roberto [Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador São Carlense, 400, Arnold Schimidt, 13566-590 São Carlos, SP (Brazil); Varela, José Arana; Longo, Elson [INCTMN/LIEC, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, R. Francisco Degni, 55, Bairro Quitandinha, 14801-907 Araraquara, SP (Brazil)

    2015-09-15

    For this research, we studied the influence of titanium tetrachloride (TC) and titanium tetraisopropoxide (TTP) precursors on CaTiO{sub 3} (CTO) synthesis by employing a microwave-assisted hydrothermal (MAH) method regarding their respective short-, medium- and long-range features to determine if the use of different titanium precursors enhances the structural evolution of the material. The growth mechanism for the formation of the micro-cube-shaped CTO is proposed to obtain nanoparticle aggregation of self-assembly nanoplates. The disorder coupled to the oxygen vacancies of [TiO{sub 5}]–[TiO{sub 6}] in complex clusters in the CTO 1 powder and twists in bonding between the [TiO{sub 6}]–[TiO{sub 6}] complex clusters in the CTO 2 powder were mainly responsible for photoluminescent (PL) emission. - Highlights: • Different titanium precursors enhance the structural evolution of the material. • [TiO{sub 5}]–[TiO{sub 6}] and twists in bonding [TiO{sub 6}]–[TiO{sub 6}] were responsible for PL emission. • Micro-cube shaped was formed by nanoparticle aggregation of self-assembly nanoplates.

  1. Preparation of TiFe based alloys melted by CaO crucible and its hydrogen storage properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chong-he, E-mail: chli@staff.shu.edu.cn [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China); He, Jin; Zhang, Zhao; Yang, Bo; Leng, Hai-yan [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Lu, Xiong-gang, E-mail: luxg@staff.shu.edu.cn [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China); Li, Zhi-lin; Wu, Zhu [Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Wang, Hong-bin [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China)

    2015-01-05

    Highlights: • The home-made CaO crucible was used to prepare the TiFe based alloys. • The compositions as well as the content of oxygen can be effectively controlled. • The microstructure of the alloy melted by CaO crucible is dendrite. • The samples performed a good hydrogen storage performance. • The CaO crucible may be the promising candidate for melting the TiFe based alloys. - Abstract: The carbon contamination of alloys prepared by the electro graphite crucible is impossible to avoid due to the inherit reaction between the melt and the crucible. In this study, the TiFe-based alloy is prepared by VIM process using CaO crucible as well as the electro graphite crucible. The samples are examined by means of Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Energy Dispersive Spectrometer (EDS), and the PCT curves are also measured. It is resulted that, the oxygen content of alloys melted by CaO crucible is almost equal to the one melted by graphite crucible and without the carbon contamination, meanwhile the carbon content of alloys obtained by the electro graphite crucible is 1860 ppm, which exceeds the tolerance of the commercial alloy (1000 ppm). The microstructure of the alloy melted by CaO crucible is dendrite, while it is composed of the equiaxed crystal with the lamellar structure and the spherical TiC particles distributed along grain boundaries or within the grain when melted by the graphite crucible; the interfacial reaction of the electro graphite crucible with TiFe alloy melt is serious and the interaction layer is formed up to 200 μm in thickness, the carbon in TiFe-based alloys forms TiC. The hydrogen desorption plateau pressure of alloys melted by CaO crucible is (0.11–0.4) × 10{sup 5} Pa, and that by the graphite crucible is (0.6–1) × 10{sup 5} Pa. This may imply that the CaO crucible may be the promising candidate for melting the high performance TiFe based hydrogen storage alloys.

  2. Study on Ferroelectric and Dielectric Properties of La-Doped CaBi4Ti4O15-Based Ceramics

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Lanthanum doped bismuth layer structured ferroelectrics (BLSFs) Ca1-xLaxBi4(Ti0.9W0.1)4O15 (x=0, 0.2, 0.3, 0.4, 0.6) ceramics were prepared by solid-state reaction method. X-ray diffraction(XRD) patterns showed that single phase was formed when x=0~0.6. The effects of La3+ doping on dielectric, piezoelectric and ferroelectric properties of Ca1-xLaxBi4(Ti0.9W0.1)4O15 ceramics were studied. Ca0.7La0.3Bi4(Ti0.9W0.1)4O15 ceramic had optimal properties, its dielectric constant was 166.85, dielectric loss was 0.0063, piezoelectric strain constant was 11 pc·N-1, remanent polarization was 18.1 μC·cm-2 and coercive field was 118 kV·cm-1. SEM micrographs showed that the grains of CaBi4Ti4O15-based ceramics were plate-like. The results of energy spectrum analysis (EDS) showed that La3+ incorporation could increase Bi/Ca ratio.

  3. Solid state synthesis and structural refinement of polycrystalline LaCa1-TiO3 ceramic powder

    Indian Academy of Sciences (India)

    O P Shrivastava; Narendra Kumar; I B Sharma

    2004-04-01

    Perovskite structure based ceramic precursors have a characteristic property of substitution in the ``A" site of the ABO3 structure. This makes them a potential material for nuclear waste management in synthetic rock (SYNROC) technology. In order to simulate the mechanism of rare earth fixation in perovskite, La Ca1-TiO3 (where = 0.05) has been synthesized through ceramic route by taking calculated quantities of oxides of Ca, Ti and La as starting materials. Solid state synthesis has been carried out by repeated pelletizing and sintering the finely powdered oxide mixture in a muffle furnace at 1050°C. The ceramic phase has been characterized by its powder diffraction pattern. Step analysis data has been used to determine the structure of solid solution of lanthanum substituted calcium titanate. The SEM and EDAX analyses also confirm that the CaTiO3 can act as a host for lanthanum. X-ray data has been interpreted using CRYSFIRE and POWDERCELL softwares. The ℎ, , values for different lattice planes have been generated from the experimental data. The lanthanum substituted perovskite crystallizes in orthorhombic symmetry with space group (#62). Following unit cell parameters have been calculated: = 5.410, = 7.631, = 5.382. The calculated and observed values of corresponding intensities, 2, and density show good agreement. GSAS based calculation for bond distances Ti–O, Ca–O, La–O and bond angles Ti–O–Ca, Ca–O–Ca, La–O–Ti have been reported.

  4. Effect of replacement of Ca by Zn on the structure and optical property of CaTiO3:Eu(3+) red phosphor prepared by sol-gel method.

    Science.gov (United States)

    Wang, Yulong; Zhang, Wentao; Zhang, Peicong; Li, Junfeng; Long, Jianping

    2015-08-01

    Eu(3+)-doped calcium titanate red phosphors, Ca(1-x)Znx TiO3:Eu(3+), were prepared by the sol-gel method. The structure of prepared Ca(1-x)Znx TiO3:Eu(3+) phosphors were investigated by X-ray diffraction and infrared spectra. Due to the (5) D0  → (7) F1-3 electron transitions of Eu(3+) ions, photoluminescence spectra showed a red emission at about 619 nm under excitation of 397 nm and 465 nm, respectively. When zinc was added to the host, the luminescent intensity of Ca(1-x)ZnxTiO3:Eu(3+) was markedly improved several fold compared with that of CaTiO3:Eu(3+). Ca0.9Zn0.1TiO3:Eu(3+) also had higher luminescence intensity than the commercially available Y2 O3:Eu(3+) phosphors under UV light excitation.

  5. Field induced domain switching as the origin of anomalous lattice strain along non-polar direction in rhombohedral BiScO{sub 3}-PbTiO{sub 3} close to the morphotropic phase boundary

    Energy Technology Data Exchange (ETDEWEB)

    Lalitha, K. V.; Ranjan, Rajeev, E-mail: rajeev@materials.iisc.ernt.in [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India); Fancher, Chris M.; Jones, Jacob L. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2015-08-03

    The lattice strain and domain switching behavior of xBiScO{sub 3}–(1-x)PbTiO{sub 3} (x = 0.40) was investigated as a function of cyclic field and grain orientation by in situ X-ray diffraction during application of electric fields. The electric field induced 200 lattice strain was measured to be five times larger than the 111 lattice strain in pseudorhombohedral xBiScO{sub 3}–(1-x)PbTiO{sub 3} (x = 0.40). It is shown that the anomalous 200 lattice strain is not an intrinsic phenomenon, but arises primarily due to stress associated with the reorientation of the 111 domains in dense polycrystalline ceramic.

  6. Magnetic phase diagrams and lattice structure of Nd sub 1 sub / sub 2 Ca sub 1 sub / sub 2 (Mn sub 1 sub - sub y M sub y)O sub 3 (M = Ru, Cr and Sc)

    CERN Document Server

    Xu, S; Nakamura, A; Machida, A; Ohoyama, K

    2003-01-01

    We have derived the magnetic phase diagram for Nd sub 1 sub / sub 2 Ca sub 1 sub / sub 2 (Mn sub 1 sub - sub y M sub y)O sub 3 (M = Ru, Cr and Sc) based on the neutron powder diffraction measurements. We found that the Ru- and Cr-doping induces an antiferromagnetic-to-ferromagnetic transition at y = 0.01 - 0.02, while the Sc-doping does not induce the transition up to y = 0.10. We have found significant dopant dependent effects on the distortion of the MnO sub 6 octahedra in the heavily-doped region of the long-c phase: the MnO sub 6 shape approached to the 2-long/4-short type with Ru-doping, while it does to the 4-long/2-short type with Sc-doping. Absence of the ferromagnetic phase in the Sc-doped system can be ascribed to (1) a strong charge-ordering instability due to the 4-long/2-short type distortion of the MnO sub 6 octahedra and (2) the reduced effective one-electron bandwidth due to the Sc sup 3 sup + (d sup 0) impurities. (author)

  7. Partition coefficients for Al, Ca, Ti, Cr, and Ni in olivine obtained by melting experiment on an LL6 chondrite

    Science.gov (United States)

    Miyamoto, M.; Mikouchi, T.; Mckay, G. A.

    1994-01-01

    We report the partition coefficients for Ca, Al, Ti, Cr, and Ni in olivine obtained through a series of melting experiments on an LL6 chondrite under varying conditions of temperature and oxygen fugacity. It is necessary to examine the variation of partition coefficients up to extremely reducing conditions in order to study meteoritic olivines. For Ca, Al, and Cr, the partition coefficients tend to decrease as temperature increases, but do not change even under extremely reducing conditions.

  8. 难熔固体MX(M=Sc, Ti, V; X=C, N, O)电子结构和力学性质的密度泛函研究%A Density Functional Study on the Electronic Structures and Mechanic Property of MX (M=Sc, Ti, V; X=C, N, O) Solids

    Institute of Scientific and Technical Information of China (English)

    李俊篯; 章永凡

    2001-01-01

    采用密度泛函方法对MX(M=Sc, Ti, V; X=C, N, O)固体的体相电子结构和力学性质进行了系统研究. 计算结果表明, 对于金属原子相同的同一系列化合物, 氮化物具有最大的体模量; 进一步的研究可知, 随着外界压力的增大, 化合物由NaCl构型向CsCl构型转变由易到难的顺序依次是氧化物、 氮化物和碳化物. 本文还首次用密度泛函方法系统地计算了各化合物的能带结构和态密度, 并对该类型化合物的导电性能进行了探讨.%The electronic structures and mechanic properties of MX (M=Sc, Ti, V; X=C, N, O) solids are investigated by using density functional theory(DFT). The results show that the mononitrides have the greatest bulk modulus. Under high compression, the calculations indicate that all compounds will undergo a structural phase transition from NaCl to CsCl structure, and the transition volume decreases from MC→MN→MO. The band structures and density of states of each compound are also calculated by DFT method, and the conductivity of this class of compounds is discussed.

  9. Sequential elucidation of the β-Ca3(PO4)2/TiO2 composite development from the solution precursors.

    Science.gov (United States)

    Nandha Kumar, P; Kannan, S

    2017-03-07

    The sequential formation of β-Ca3(PO4)2/TiO2 composites with assorted ratios synthesized from the solution precursors is described. The phase evolution of the synthesized powders to yield a composite during progressive heat treatments is determined through a set of analytical techniques. Investigation reveals the initial crystallization of apatite and anatase TiO2 (a-TiO2) mixtures at TiO2 (r-TiO2) transpires in the range of 800-1000 °C before the complete r-TiO2 transformation accomplishes at 1100 °C. The structural stability of the resultant β-Ca3(PO4)2/r-TiO2 composites is retained until 1300 °C. The β-Ca3(PO4)2 lattice also hosts a selective amount of Ti(4+) and as a consequence the anticipated β- → α-Ca3(PO4)2 conversion that occurs at 1180 °C is delayed. TiO2 plays a crucial role in the attainment of dense and pore free microstructures of β-Ca3(PO4)2/r-TiO2 composites. The mechanical properties determined through nanoindentation revealed an upsurge trend as a function of TiO2 content in the composites.

  10. Tuning of Photoluminescence by Cation Nanosegregation in the (CaMg) x (NaSc) 1–x Si 2 O 6 Solid Solution

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Zhiguo; Liu, Guokui; Wen, Jianguo; Mei, Zhigang; Balasubramanian, Mahalingam; Molokeev, Maxim S.; Peng, Licong; Gu, Lin; Miller, Dean J.; Liu, Quanlin; Poeppelmeier, Kenneth R.

    2016-02-03

    Controlled photoluminescence tuning is important for the optimization and modification of phosphor materials. Herein we report an isostructural solid solution of (CaMg)x(NaSc)1-xSi2O6 (0 < x < 1) in which cation nanosegregation leads to the presence of two dilute Eu2+ centers. The distinct nanodomains of isostructural (CaMg)Si2O6 and (NaSc)Si2O6 contain a proportional number of Eu2+ ions with unique, independent spectroscopic signatures. Density functional theory calculations provided a theoretical understanding of the nanosegregation and indicated that the homogeneous solid solution is energetically unstable. It is shown that nanosegregation allows predictive control of color rendering and therefore provides a new method of phosphor development.

  11. Investigations of the effect of nonmagnetic Ca substitution for magnetic Dy on spin-freezing in Dy2Ti2O7

    Science.gov (United States)

    Anand, V. K.; Tennant, D. A.; Lake, B.

    2015-11-01

    Physical properties of partially Ca substituted hole-doped Dy2Ti2O7 have been investigated by ac magnetic susceptibility {χ\\text{ac}}(T) , dc magnetic susceptibility χ (T) , isothermal magnetization M(H) and heat capacity {{C}\\text{p}}(T) measurements on Dy1.8Ca0.2Ti2O7. The spin-ice system Dy2Ti2O7 exhibits a spin-glass type freezing behavior near 16 K. Our frequency dependent {χ\\text{ac}}(T) data of Dy1.8Ca0.2Ti2O7 show that the spin-freezing behavior is significantly influenced by Ca substitution. The effect of partial nonmagnetic Ca2+ substitution for magnetic Dy3+ is similar to the previous study on nonmagnetic isovalent Y3+ substituted Dy2-x Y x Ti2O7 (for low levels of dilution), however the suppression of spin-freezing behavior is substantially stronger for Ca than Y. The Cole-Cole plot analysis reveals semicircular character and a single relaxation mode in Dy1.8Ca0.2Ti2O7 as for Dy2Ti2O7. No noticeable change in the insulating behavior of Dy2Ti2O7 results from the holes produced by 10% Ca2+ substitution for Dy3+ ions.

  12. Preparation of CaTiO3:Pr3+Red Persistent Phosphors%CaTiO3:Pr3+红色蓄能发光材料的研究

    Institute of Scientific and Technical Information of China (English)

    朱小平; 梁耀龙; 刘俊荣; 于长凤; 张缇

    2014-01-01

    以碳酸钙、氧化锌、二氧化钛为主要原料,以氧化镨为激活剂,以氧化铕为辅助激活剂,以碳酸钠为电荷补偿剂,以硼酸为助熔剂,采用高温固相法对红色CaTiO3:Pr3+蓄光材料进行了试制研究。试制得到荧光余辉时间达20 min左右、发光效果良好的CaTiO3:Pr3+系红色荧光材料。对合成的荧光粉末进行了XRD、激发光谱分析检测,表明合成所得荧光粉的主晶相为CaTiO3。试验结果表明,在配料组成确定后,合成温度和保温时间对发光效果的影响较大。当合成温度为1100℃,保温时间为2h制备得到的荧光材料发光效果良好。%A series of tests were developed around CaTiO3:Pr3+red lfuorescent material. In this study, CaTiO3:Pr3+red persistent phosphors with good glowing effect and about 20 minutes’ decay time were prepared by high-temperature solid-phase method with CaCO3, ZnO, TiO2 as main raw materials, Pr2O3 as the activate agent, Eu2O3 as auxiliary activators, Na2CO3 as compensate for the charge, as lfux.Samples were characterized by means of powder X-ray diffraction (XRD) and laser spectral analysis. Result showed that main phase of the synthesized lfuorescent powder was CaTiO3:Pr3+. Results shown that glowing effect were signiifcantly inlfuenced by synthesis temperature and the soaking time, when composition determined, Optimum synthetic temperature was 1100℃, and soaking time was 2 hours..

  13. Inelastic neutron scattering and lattice dynamics of NaNbO3 and Sr0.70Ca0.30TiO3

    Indian Academy of Sciences (India)

    S K Mishra; R Mittal; N Choudhury; S L Chaplot; D Pandey

    2008-11-01

    NaNbO3 and (Sr,Ca)TiO3 exhibit an unusual complex sequence of temperature- and pressure-driven structural phase transitions. We have carried out lattice dynamical studies to understand the phonon modes responsible for these phase transitions. Inelastic neutron scattering measurements using powder samples were carried out at the Dhruva reactor, which provide the phonon density of states. Lattice dynamical models have been developed for SrTiO3 and CaTiO3 which have been fruitfully employed to study the phonon spectra and vibrational properties of the solid solution (Sr,Ca)TiO3.

  14. Microwave synthesis and sintering characteristics of CaCu3Ti4O12

    Indian Academy of Sciences (India)

    P Thomas; L N Sathapathy; K Dwarakanath; K B R Varma

    2007-12-01

    CaCu3Ti4O12 (CCTO) was synthesized and sintered by microwave processing at 2.45 GHz, 1.1 kW. The optimum calcination temperature using microwave heating was determined to be 950°C for 20 min to obtain cubic CCTO powders. The microwave processed powders were sintered to 94% density at 1000°C/60 min. The microstructural studies carried out on these ceramics revealed the grain size to be in the range 1–7 m. The dielectric constants for the microwave sintered (1000°C/60 min) ceramics were found to vary from 11000–7700 in the 100 Hz–100 kHz frequency range. Interestingly the dielectric loss had lower values than those sintered by conventional sintering routes and decreases with increase in frequency.

  15. Chemical solution deposition of CaCu3Ti4O12 thin film

    Indian Academy of Sciences (India)

    Viswanathan S Saji; Han Cheol Choe

    2010-06-01

    CaCu3Ti4O12 (CCTO) thin film was successfully deposited on boron doped silica substrate by chemical solution deposition and rapid thermal processing. The phase and microstructure of the deposited films were studied as a function of sintering temperature, employing X-ray diffractometry and scanning electron microscopy. Dielectric properties of the films were measured at room temperature using impedance spectroscopy. Polycrystalline pure phase CCTO thin films with (220) preferential orientation was obtained at a sintering temperature of 750°C. There was a bimodal size distribution of grains. The dielectric constant and loss factor at 1 kHz obtained for a film sintered at 750°C was ∼ 2000 and tan ∼ 0.05.

  16. Sintering behavior and microwave dielectric properties of (1-x)CaTiO3-xLaAIO3 ceramics

    Institute of Scientific and Technical Information of China (English)

    HOU Guihua; WANG Zhanhong; ZHANG Feng

    2011-01-01

    The sintering behavior, microstructure and microwave dielectric properties of (1-x)CaTiO3-xLaAlO3 (x=0.1, 0.3, 0.5, 0.7, 0.9, respectively) ceramics were investigated systematically by thermogravimetry-differential thermal analysis (TG-DSC), X-ray diffraction (XRD),scanning electron microscopy (SEM) and a network analyzer. The result showed that forming temperature of the perovskite type crystal increased with increasing of x value. 0.9CaTiO3-0.1LaAlO3 ceramics were sintered well from 1 400 to 1 550 ℃, its bulk density increased with sintering temperature, and microwave dielectric properties of the ceramics at 1 400 ℃ was shown as follows: relative dielectric constant εr=45.1, Q×f= 46 087 GHz and τf-14. 1 × 10-6/℃, respectively. But 0.7CaTiO3-0.3LaAlO3 ceramics were sintered well only when sintering temperature rose to 1 500 ℃. (1-x)CaTiO3_xLaA1O3 (.x=0.5, 0.7 and 0.9, respectively) were not sintered well up to 1 550 ℃ and the sintered samples exhibited porous characteristic and with low bulk density.

  17. Improvement in antibacterial properties of Ti by electrodeposition of biomimetic Ca-P apatite coat on anodized titania

    Energy Technology Data Exchange (ETDEWEB)

    Gad El-Rab, Sanaa M.F. [Biotechnology Department, Faculty of Science, Taif University, Taif (Saudi Arabia); Botany Department, Faculty of Science, Asuit University, Asuit (Egypt); Fadl-allah, Sahar A., E-mail: Sahar.fadlallah@yahoo.com [Materials and Corrosion Lab (MCL), Faculty of Science, Taif University, Taif (Saudi Arabia); Chemistry Department, Faculty of Science, Cairo University, Cairo (Egypt); Montser, A.A. [Materials and Corrosion Lab (MCL), Faculty of Science, Taif University, Taif (Saudi Arabia); Chemistry Department, Faculty of Science, South-Valley University (Egypt)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Ca-P coating on titania titanium surface was directly fabricated successfully by electrochemical deposition. Black-Right-Pointing-Pointer Treatment the titanium surface by TiO{sub 2} could improve the adhesion strength between the Ca-P coating and the surface. Black-Right-Pointing-Pointer Anodization treatment in phosphoric acid is benefit to inhibit the oral bacteria. Black-Right-Pointing-Pointer According to the electrochemical corrosion test, corrosion resistance of Ti was improved by both anodization and electrodeposition of the Ca-P/titania coating. Black-Right-Pointing-Pointer Ca-P/titania sample is believed to be a functional biomaterial which combines antibacterial activity and good corrosion resistance in bioenvironment. - Abstract: Titanium metal (Ti) with antibacterial function was successfully developed in the present study by electrodeposition of biomimetic Ca-P coat in simple supersaturated calcium and phosphate solution (SCPS). The electrochemical behavior and corrosion resistance of Ca-P deposited on anodized titanium (AT) have been investigated in SCPS by using electrochemical impedance spectroscopy (EIS). The plate-counting method was used to evaluate the antibacterial performance against Staphylococcus aureus (ATCC6538). In vitro antibacterial activity study indicated a significantly reduced number of bacteria S. aureus on Ca-P/AT plate surface when compared with that on Ti or AT surfaces and the corresponding antibacterial mechanism is discussed. The morphology and chemical structure of different titanium samples were systematically investigated by scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX). The study confirmed that the antibacterial properties of the samples were related to chemical composition of sample surface.

  18. In situ scanning tunneling microscopy study of Ca-modified rutile TiO2(110 in bulk water

    Directory of Open Access Journals (Sweden)

    Giulia Serrano

    2015-02-01

    Full Text Available Despite the rising technological interest in the use of calcium-modified TiO2 surfaces in biomedical implants, the Ca/TiO2 interface has not been studied in an aqueous environment. This investigation is the first report on the use of in situ scanning tunneling microscopy (STM to study calcium-modified rutile TiO2(110 surfaces immersed in high purity water. The TiO2 surface was prepared under ultrahigh vacuum (UHV with repeated sputtering/annealing cycles. Low energy electron diffraction (LEED analysis shows a pattern typical for the surface segregation of calcium, which is present as an impurity on the TiO2 bulk. In situ STM images of the surface in bulk water exhibit one-dimensional rows of segregated calcium regularly aligned with the [001] crystal direction. The in situ-characterized morphology and structure of this Ca-modified TiO2 surface are discussed and compared with UHV-STM results from the literature. Prolonged immersion (two days in the liquid leads to degradation of the overlayer, resulting in a disordered surface. X-ray photoelectron spectroscopy, performed after immersion in water, confirms the presence of calcium.

  19. Electrochemical Deposition of Si-Ca/P on Nanotube Formed Beta Ti Alloy by Cyclic Voltammetry Method.

    Science.gov (United States)

    Jeong, Yong-Hoon; Choe, Han-Cheol

    2015-08-01

    The purpose of this study was to investigate electrochemical deposition of Si-Ca/P on nanotube formed Ti-35Nb-10Zr alloy by cyclic voltammetry method. Electrochemical deposition of Si substituted Ca/P was performed by pulsing the applied potential on nanotube formed surface. The surface characteristics were observed by field-emission scanning electron microscopy, X-ray diffractometer, and potentiodynamic polarization test. The phase structure and surface morphologies of Si-Ca/P deposition were affected by deposition cycles. From the anodic polarization test, nanotube formed surface at 20 V showed the high corrosion resistance with lower value of Icorr, I300, and Ipass.

  20. Enhanced Mechanical Properties of MgZnCa Bulk Metallic Glass Composites with Ti-Particle Dispersion

    Directory of Open Access Journals (Sweden)

    Pei Chun Wong

    2016-05-01

    Full Text Available Rod samples of Mg60Zn35Ca5 bulk metallic glass composites (BMGCs dispersed with Ti particles have been successfully fabricated via injection casting. The glass forming ability (GFA and the mechanical properties of these Mg-based BMGCs have been systematically investigated as a function of the volume fraction (Vf of Ti particles. The results showed that the compressive ductility increased with Vf. The mechanical performance of these BMGCs, with up to 5.4% compressive failure strain and 1187 MPa fracture strength at room temperature, can be obtained for the Mg-based BMGCs with 50 vol % Ti particles, suggesting that these dispersed Ti particles can absorb the energy of the crack propagations and can induce branches of the primary shear band into multiple secondary shear bands. It follows that further propagation of the shear band is blocked, enhancing the overall plasticity.

  1. Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Sc, Ti, V, Cu and Zn

    Energy Technology Data Exchange (ETDEWEB)

    Biesinger, Mark C., E-mail: biesingr@uwo.ca [Surface Science Western, University of Western Ontario, University of Western Ontario Research Park, Room LL31, 999 Collip Circle, London, Ontario, N6G 0J3 (Canada); ACeSSS (Applied Centre for Structural and Synchrotron Studies), University of South Australia, Mawson Lakes, SA 5095 (Australia); Lau, Leo W.M. [Surface Science Western, University of Western Ontario, University of Western Ontario Research Park, Room LL31, 999 Collip Circle, London, Ontario, N6G 0J3 (Canada); Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Gerson, Andrea R.; Smart, Roger St.C. [ACeSSS (Applied Centre for Structural and Synchrotron Studies), University of South Australia, Mawson Lakes, SA 5095 (Australia)

    2010-11-15

    Chemical state X-ray photoelectron spectroscopic analysis of first row transition metals and their oxides and hydroxides is challenging due to the complexity of the 2p spectra resulting from peak asymmetries, complex multiplet splitting, shake-up and plasmon loss structure, and uncertain, overlapping binding energies. A review of current literature shows that all values necessary for reproducible, quantitative chemical state analysis are usually not provided. This paper reports a more consistent, practical and effective approach to curve-fitting the various chemical states in a variety of Sc, Ti, V, Cu and Zn metals, oxides and hydroxides. The curve-fitting procedures proposed are based on a combination of (1) standard spectra from quality reference samples, (2) a survey of appropriate literature databases and/or a compilation of the literature references, and (3) specific literature references where fitting procedures are available. Binding energies, full-width at half maximum (FWHM) values, spin-orbit splitting values, asymmetric peak-shape fitting parameters, and, for Cu and Zn, Auger parameters values are presented. The quantification procedure for Cu species details the use of the shake-up satellites for Cu(II)-containing compounds and the exact binding energies of the Cu(0) and Cu(I) peaks. The use of the modified Auger parameter for Cu and Zn species allows for corroborating evidence when there is uncertainty in the binding energy assignment. These procedures can remove uncertainties in analysis of surface states in nano-particles, corrosion, catalysis and surface-engineered materials.

  2. First Principles Study of Dopant Site Selectivity in Ordered Perovskite CaCu3Ti4O12

    Institute of Scientific and Technical Information of China (English)

    XU Li-Chun; WANG Ru-Zhi; DENG Yang; YAN Hui

    2011-01-01

    We investigate the dopant site selectivity of CaCu3Ti4O12(CCTO) using the first principles calculations. Our results show that, for four cases of possible occupancy by La atom, lattice expansions and formation enthalpies with different dopant quantities indicate that doped La cations are preferentially substituted for Ca sites in CaCu3Ti4O12, which is excellent in agreement with the experimental observation(Choi et al. Adv. Mater. 21 (2009) 885).Furthermore, more interesting information of doping is also explored by the analysis of density of states and it is found that La substituting for Cu may advance the electron conduction in CCTO. It supplies a potential solution for limitations of CCTO devices by exploring the effect when La substitutes for Cu sites in the CCTO crystal.

  3. Study of new sheep bone and Zn/Ca ratio around TiAlV screw: PIXE-RBS analysis

    Energy Technology Data Exchange (ETDEWEB)

    Guibert, G. [Haute Ecole Arc Ingenierie, IMA-Arc-NEODE, 17 Eplatures-Grise, CH-2300 La Chaux-de-Fonds (Switzerland)], E-mail: geoffroy.guibert@he-arc.ch; Munnik, F. [Haute Ecole Arc Ingenierie, IMA-Arc-NEODE, 17 Eplatures-Grise, CH-2300 La Chaux-de-Fonds (Switzerland); Langhoff, J.D.; Von Rechenberg, B. [MSRU, Universitaet Zuerich, CH-8057 Zuerich (Switzerland); Buffat, Ph.A.; Laub, D. [EPFL-CIME, CH-1015 Lausanne (Switzerland); Faber, L.; Ducret, F. [DePuy ACE, CH-2400 Le Locle (Switzerland); Gerber, I. [Institute of Cell Biology, ETH Hoenggerberg, CH-8093 Zurich (Switzerland); Mikhailov, S. [Haute Ecole Arc Ingenierie, IMA-Arc-NEODE, 17 Eplatures-Grise, CH-2300 La Chaux-de-Fonds (Switzerland)

    2008-03-15

    This study reports on in vivo particle induced X-ray emission (PIXE) measurements combined with Rutherford backscattering spectroscopy (RBS) analyses of new remodeled sheep bone formed around TiAlV screws. The implants (screws) were anodized by a modified TiMax{sup TM} process. The interface between the implant and the bone was carefully investigated. [Zn]/[Ca] in-depth composition profiles as well as Ca, Fe elemental maps were recorded. The thickness of new bone formed around the screw reached 300-400 {mu}m. Osteon and Osteoid phases were identified in the new bone. A higher [Zn]/[Ca] ratio was observed in the new bone as compared to the mature bone. Blood vessels were observed in the bone in close contact with the screw. This study shows the potential of ion beam analysis for biological and biomedical characterization.

  4. First measurement of the nonlinear coefficient for Gd1-xLux Ca4O(BO3)3 and Gd1-xScxCa4O(BO3)3 crystals

    DEFF Research Database (Denmark)

    Andersen, Martin Thalbitzer; Mortensen, Jesper Liltorp; Germershausen, Sven

    2007-01-01

    The effective nonlinear coefficient and temperature acceptance bandwidth of three Lu and Sc co-doped GdCa4O(B03)3 type nonlinear crystals were measured. NCPM for SHG in to the blue-UV spectral region can be obtained by controlling the co-dopant concentration. Measurements were based on intra-cavi...

  5. Analysis of 4He+40Ca and 4He+44Ti scattering using different optical model potentials

    Science.gov (United States)

    Ibraheem, Awad A.

    2016-09-01

    Elastic scattering of 4He+40Ca and 4He+44Ti reactions at backward angles has been analyzed using two differentmodels, microscopic and semimicroscopic folding potentials. The derived real potentials supplemented with phenomenological Woods-Saxon imaginary potentials, provide good agreement with the experimental data at energy E c.m. = 21.8 MeV without need to renormalize the potentials. Coupledchannels calculations are used to extract the inelastic scattering cross section to the low-lying state 2+ (1.083 MeV) of 44Ti. The deformation length is obtained and compared with the electromagnetic measurement values as well as those obtained from previous studies.

  6. Effects of Ti-Based Additives on the Hydrogen Storage Properties of a LiBH4/CaH2 Destabilized System

    Directory of Open Access Journals (Sweden)

    Hongwei Yang

    2010-01-01

    Full Text Available The hydrogen storage properties of a destabilized LiBH4/CaH2 system ball-milled with TiCl3, TiF3, and TiO2 additives have been investigated. It is found that the system with TiCl3 additive has a lower dehydrogenation temperature than the ones with other additives. Further study shows that a higher amount of TiCl3 is more effective in reducing the desorption temperature of the LiBH4/CaH2 system, since it leads to a lower activation energy of dehydrogenation. The activations energies for mixtures containing 4, 10, and 25 mol% of TiCl3 are 141, 126, and 110 kJ/mol, respectively. However, the benefits of higher amounts of TiCl3 are offset by a larger reduction in hydrogen capacity of the mixtures.

  7. Investigation of structural and optical properties of CaTiO{sub 3} powders doped with Mg{sup 2+} and Eu{sup 3+} ions

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Larissa H., E-mail: larissahelena2009@gmail.com [Institute of Chemistry, State University of São Paulo, 14800-900, Araraquara, São Paulo (Brazil); Savioli, Julia [Department of Chemistry, Federal University of São Carlos, 13565-905, São Carlos, São Paulo (Brazil); Moura, Ana P. de [Institute of Chemistry, State University of São Paulo, 14800-900, Araraquara, São Paulo (Brazil); Nogueira, Içamira C. [Department of Chemistry, Federal University of São Carlos, 13565-905, São Carlos, São Paulo (Brazil); Li, Maximo S. [Institute of Physics, University of São Paulo, P.O. Box, 13566-590, São Carlos, São Paulo (Brazil); Longo, Elson; Varela, José A. [Institute of Chemistry, State University of São Paulo, 14800-900, Araraquara, São Paulo (Brazil); Rosa, Ieda L.V. [Department of Chemistry, Federal University of São Carlos, 13565-905, São Carlos, São Paulo (Brazil)

    2015-10-25

    In this work, CaTiO{sub 3} powders doped with Mg{sup 2+} ions and CaTiO{sub 3} powders co-doped with Mg{sup 2+} and Eu{sup 3+} ions were prepared by the polymeric precursor method (PPM). These powders were characterized by different characterization techniques to study the influence of Mg{sup 2+} doping as well as Mg{sup 2+} and Eu{sup 3+} co-doping in structural and optical properties of CaTiO{sub 3} perovskite-type structure. The Rietveld refinement and Micro-Raman analyses suggested the substitution Mg{sup 2+} and Eu{sup 3+} ions in the A-site of CaTiO{sub 3} perovskite. The influence of Mg{sup 2+} doping can be detected by the displacement of calcium and oxygen atomic positions when compared to the non-doped CaTiO{sub 3} powder. When Eu{sup 3+} ions are added to the A-site of this perovskite the excess of positive charge can be compensated by the formation of calcium vacancies. Luminescence data showed that Ca{sub 1-x}Mg{sub x}TiO{sub 3} and Ca{sub 1x}Mg{sub x/2}Eu{sub 2y/3}TiO{sub 3} powders are potential materials for fabrication of lighting devices based on near-UV and blue LED using an excitation wavelength of 397 and/or 450 nm. - Highlights: • CaTiO{sub 3} co-doped with Mg{sup 2+} and Eu{sup 3+} were obtained by the Polymeric Precursor Method. • Incorporation of Mg{sup 2+} and Eu{sup 3+} ions in the CaTiO{sub 3} lattice. • Enhancement of the Eu{sup 3+} photoluminescence.

  8. Fabrication and performance testing of CaO insulator coatings on V-5%Cr-5%Ti in liquid lithium

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Dragel, G. [Argonne National Lab., Chicago, IL (United States)

    1995-04-01

    Corrosion resistance of structural materials, and the magnetohydrodynamic (MHD) force and its influence on thermal hydraulics and corrosion, are major concerns in the design of liquid-metal blankets for magnetic fusion reactors (MFRs). The objective of this study is to develop in-situ stable coatings at the liquid-metal/structural-material interface, with emphasis on coatings that can be converted to an electrically insulating film to prevent adverse currents that are generated by the MHD force from passing through the structural walls. The electrical resistance of CaO coatings produced on V-5Cr-5Ti by exposure of the alloy to liquid Li that contained 0.5 - 8.5 wt.% dissolved Ca was measured as a function of time at temperatures between 250 and 600{degree}C. The solute element, Ca in liquid Li, reacted with the alloy substrate at 400-420{degree}C to produce a CaO coating.

  9. Mg, Al, Si, Ca, Ti, Fe, and Ni abundance for a sample of solar analogues

    Science.gov (United States)

    López-Valdivia, Ricardo; Bertone, Emanuele; Chávez, Miguel

    2017-01-01

    We report on the determination of chemical abundances of 38 solar analogues, including 11 objects previously identified as super metal-rich stars. We have measured the equivalent widths for 34 lines of 7 different chemical elements (Mg, Al, Si, Ca, Ti, Fe, and Ni) in high-resolution (R ˜ 80 000) spectroscopic images, obtained at the Observatorio Astrofísico Guillermo Haro (Sonora, Mexico), with the Cananea High-resolution Spectrograph. We derived chemical abundances using ATLAS12 model atmospheres and the Fortran code MOOG. We confirmed the super metallicity status of 6 solar analogues. Within our sample, BD+60 600 is the most metal-rich star ([Fe/H]=+0.35 dex), while for HD 166991 we obtained the lowest iron abundance ([Fe/H]=-0.53 dex). We also computed the so-called [Ref] index for 25 of our solar analogues, and we found, that BD+60 600 ([Ref]=+0.42) and BD+28 3198 ([Ref]=+0.34) are good targets for exoplanet search.

  10. Ti K-edge XANES study of the local environment of titanium in bioresorbable TiO2-CaO-Na2O-P2O5 glasses.

    Science.gov (United States)

    Pickup, David M; Abou Neel, Ensanya A; Moss, Robert M; Wetherall, Kate M; Guerry, Paul; Smith, Mark E; Knowles, Jonathan C; Newport, Robert J

    2008-04-01

    Ti K-edge XANES (X-ray absorption near edge structure) spectroscopy has been used to study the local coordination of titanium in biocompatible and bioresorbable TiO2-CaO-Na2O-P2O5 glasses. Both conventional melt-quenched glasses of composition (TiO2)x(CaO)0.30(Na2O)0.20-x(P2O5)0.50, where x = 0.01, 0.03 and 0.05, and sol-gel derived (TiO2)0.25(CaO)0.25(P2O5)0.50 glass have been studied. The results show that in all the materials studied, titanium is surrounded by an octahedron of oxygen atoms. Further analysis reveals that the TiO6 site in the amorphous samples is not heavily distorted relative to that in rutile, anatase or CaSiTiO5. The spectra from the (TiO2)0.25(CaO)0.25(P2O5)0.50 sol-gel samples reveal greater distortion in the TiO6 site in the dried gel compared to the heat-treated sol-gel glass. The XANES spectra from melt-quenched glass samples soaked in distilled water for various times do not shown any evidence of degradation of the titanium site over periods of up to 14 days.

  11. Fusion and quasifission dynamics in the reactions $^{48}$Ca+$^{249}$Bk and $^{50}$Ti+$^{249}$Bk using TDHF

    CERN Document Server

    Umar, A S; Simenel, C

    2016-01-01

    Background: Synthesis of superheavy elements (SHE) with fusion-evaporation reactions is strongly hindered by the quasifission (QF) mechanism which prevents the formation of an equilibrated compound nucleus and which depends on the structure of the reactants. New SHE have been recently produced with doubly-magic $^{48}$Ca beams. However, SHE synthesis experiments with single-magic $^{50}$Ti beams have so far been unsuccessful. Purpose: In connection with experimental searches for $Z=117,119$ superheavy elements, we perform a theoretical study of fusion and quasifission mechanisms in $^{48}$Ca,$^{50}$Ti+$^{249}$Bk reactions in order to investigate possible differences in reaction mechanisms induced by these two projectiles. Methods: The collision dynamics and the outcome of the reactions are studied using unrestricted time-dependent Hartree-Fock (TDHF) calculations as well as the density-constrained TDHF method to extract the nucleus-nucleus potentials and the excitation energy in each fragment. Results: Nucleu...

  12. Loparite, a rare-earth ore (Ce, Na, Sr, Ca)(Ti, Nb, Ta, Fe+3)O3

    Science.gov (United States)

    Hedrick, James B.; Sinha, Shyama P.; Kosynkin, Valery D.

    1997-01-01

    The mineral loparite (Ce, NA, Sr, Ca)(Ti, Nb, Ta, Fe+3)O3 is the principal ore of the light-group rare-earth elements (LREE) in Russia. The complex oxide has a perovskite (ABO3) structure with coupled substitutions, polymorphism, defect chemistry and a tendency to become metamict. The A site generally contains weakly bonded, easily exchanged cations of the LREE, Na and Ca. The B site generally contains smaller, highly charged cations of Ti, Nb or Fe+3. Mine production is from Russia's Kola Peninsula. Ore is beneficiated to produce a 95% loparite concentrate containing 30% rare-earth oxides. Loparite concentrate is refined by either a chlorination process or acid decomposition process to recover rare-earths, titanium, niobium and tantalum. Rare-earths are separated by solvent extraction and selective precipitation/dissolution. The concentrate is processed at plants in Russia, Estonia and Kazakstan.

  13. Preparation, characterization and activity evaluation of CaZrTi{sub 2}O{sub 7} photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Chen Shifu, E-mail: chshifu@chnu.edu.cn [Department of Chemistry, Huaibei Normal University, Anhui, Huaibei 235000 (China); Ji Mingsong; Yuang Yunguang; Liu Wei [Department of Chemistry, Huaibei Normal University, Anhui, Huaibei 235000 (China)

    2012-06-15

    CaZrTi{sub 2}O{sub 7} photocatalyst sample was prepared by a polymerizable complex method. The photocatalyst was characterized by X-ray powder diffraction, scanning electron microscopy, UV-Vis diffuse reflectance spectroscopy, photoluminescence emission spectroscopy, Brunauer-Emmett-Teller analysis, N{sub 2} adsorption measurements, and terephthalic acid probed fluorescence technique. The photocatalytic activity of the sample was evaluated by photocatalytic oxidation of methyl orange and photocatalytic reduction of Cr{sub 2}O{sub 7}{sup 2-} and nitrobenzene. The results showed that when the reaction solution was illuminated by UV light for 50 min, the photooxidation efficiency of methyl orange and the photoreduction efficiency of Cr{sub 2}O{sub 7}{sup 2-} were 83.1% and 87.9%, respectively. When methanol was used as the holes scavengers and the illumination time was 10 h in the photocatalytic reduction experiment of nitrobenzene, the production efficiency of aniline was 70.3%. The effect of the heat treatment conditions on the photocatalytic activity was also investigated. The optimum preparation condition for CaZrTi{sub 2}O{sub 7} sample is 800 Degree-Sign C for 12 h. The mechanisms of influence on the photocatalytic activity of the sample were also discussed with the valance band theory. - Highlights: Black-Right-Pointing-Pointer CaZrTi{sub 2}O{sub 7} photocatalyst was prepared by a polymerizable complex method. Black-Right-Pointing-Pointer The heat treatment has a significant influence on the photocatalytic activity. Black-Right-Pointing-Pointer The optimal heat treatment condition is approximately 800 Degree-Sign C for 12 h. Black-Right-Pointing-Pointer The CaZrTi{sub 2}O{sub 7} has the band bap of about 2.89 eV with particle size of about 80 nm.

  14. High-T(c) Superconductivity at the Interface between the CaCuO2 and SrTiO3 Insulating Oxides.

    Science.gov (United States)

    Di Castro, D; Cantoni, C; Ridolfi, F; Aruta, C; Tebano, A; Yang, N; Balestrino, G

    2015-10-02

    At interfaces between complex oxides it is possible to generate electronic systems with unusual electronic properties, which are not present in the isolated oxides. One important example is the appearance of superconductivity at the interface between insulating oxides, although, until now, with very low T(c). We report the occurrence of high T(c) superconductivity in the bilayer CaCuO(2)/SrTiO(3), where both the constituent oxides are insulating. In order to obtain a superconducting state, the CaCuO(2)/SrTiO(3) interface must be realized between the Ca plane of CaCuO(2) and the TiO(2) plane of SrTiO(3). Only in this case can oxygen ions be incorporated in the interface Ca plane, acting as apical oxygen for Cu and providing holes to the CuO(2) planes. A detailed hole doping spatial profile can be obtained by scanning transmission electron microscopy and electron-energy-loss spectroscopy at the O K edge, clearly showing that the (super)conductivity is confined to about 1-2 CaCuO(2) unit cells close to the interface with SrTiO(3). The results obtained for the CaCuO(2)/SrTiO(3) interface can be extended to multilayered high T(c) cuprates, contributing to explaining the dependence of T(c) on the number of CuO(2) planes in these systems.

  15. Effect of sintering temperature on the properties of modified mechanical alloyed CaCu3Ti4O12.

    Science.gov (United States)

    Hutagalung, Sabar D; Ying, Ooi Li; Ahmad, Zainal Ahmad

    2007-12-01

    This paper presents the effects of calcination time and sintering temperature on the properties of CaCu(3)Ti(4)O(12). Electroceramic material of CaCu(3)Ti(4)O(12) was prepared using a modified mechanical alloying technique that covers several processes, which are preparation of raw material, mixing and ball milling for 5 hours, calcination, pellet forming and, sintering. The objective of this modified technique is to enable the calcination and sintering processes to be carried out at a shorter time and lower temperature. The x-ray diffraction (XRD) analysis result shows that a single-phase of CaCu(3)Ti(4)O(12) was completely formed by calcination at 750 degrees C for 12 hours. Meanwhile, the grain size of a sample sintered at 1050 degrees C for 24 hours is extremely large, in the range of 20-50 mum obtained from field emission scanning electron microscopy (FESEM) images. The dielectric constant value of 14,635 was obtained at 10 kHz by impedance (LCR) meter in the sintered sample at 1050 degrees C. However, the dielectric constant value of samples sintered at 900 and 950 degrees C is quite low, in the range of 52-119.

  16. Photoluminescence properties of CaTiO{sub 3}:Eu{sup 3+} nanophosphor obtained by the polymeric precursor method

    Energy Technology Data Exchange (ETDEWEB)

    Mazzo, Tatiana Martelli, E-mail: tatimazzo@gmail.com [INCTMN, LIEC, Departamento de Química, Universidade Federal de São Carlos, P.O. Box 676, 13565-905 São Carlos, SP (Brazil); Mendonça da Rocha Oliveira, Lucas [INCTMN, LIEC, Departamento de Química, Universidade Federal de São Carlos, P.O. Box 676, 13565-905 São Carlos, SP (Brazil); Macario, Leilane Roberta [INCTMN, LIEC, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, 14800-900 Araraquara, SP (Brazil); Avansi, Waldir [Departamento de Física, Universidade Federal de São Carlos, P.O. Box 676, 13565-905 São Carlos, SP (Brazil); Silveira André, Rafaela da; Viana Rosa, Ieda Lucia [INCTMN, LIEC, Departamento de Química, Universidade Federal de São Carlos, P.O. Box 676, 13565-905 São Carlos, SP (Brazil); Varela, José Arana; Longo, Elson [INCTMN, LIEC, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, 14800-900 Araraquara, SP (Brazil)

    2014-05-01

    Europium-doped calcium titanate nanophosphors were synthesized by the polymeric precursor method (PPM) at different temperatures. X-ray absorption near edge structure (XANES) spectroscopy reveals that the introduction of Eu{sup 3+} ions into the CaTiO{sub 3} network induces to significant changes in the local order–disorder relationship around both [TiO{sub 6}] and [CaO{sub 12}] complex clusters. The X-ray diffraction (XRD) and FT-Raman reveals that the presence of the Eu{sup 3+} ions favors the structural organization at long and short ranges, which produces a faster crystallization of the CT orthorhombic phase. The increase of the annealed temperature and the Eu{sup 3+} concentration for CT:Eu{sup 3+} powders induces to a decrease in the CT:Eu{sup 3+} nanoparticle sizes. - Graphical abstract: Display Omitted - Highlights: • Eu{sup 3+} induces changes in the order–disorder around both [TiO{sub 6}] and [CaO{sub 12}] clusters. • Eu{sup 3+} favors the organization and the crystallization of the CT orthorhombic phase. • The increase of the annealed temperature induces a decrease in the nanoparticle size. • The increase of the Eu{sup 3+} concentration induces a decrease in the nanoparticle size. • Photoluminescence spectra show Eu{sup 3+} emission lines ascribed to Eu{sup 3+} transitions.

  17. New perovskite-related oxides having high dielectric constant: Ln2Ba2CaZn2Ti3O14 (Ln = La and Pr)

    Indian Academy of Sciences (India)

    Pika Jha; Ashok K Ganguli

    2003-10-01

    Two new oxides, La2Ba2CaZn2Ti3O14 and Pr2Ba2CaZn2Ti3O14, have been synthesized by the ceramic route at 1100°C. These oxides crystallize in the disordered cubic structure with an `a’ lattice parameter of 3.9728 (2) and 3.9448 (5) respectively. These oxides show high dielectric constant (70 and 57) and low loss (0.003 and 0.013 at 100 kHz) for La2Ba2CaZn2Ti)3O14 and Pr2Ba2CaZn2Ti3O14 respectively. The dielectric constant is highly stable with frequency and temperature.

  18. Rapid stability of ferroelectric polarization in the Ca, Ce hybrid doped BaTiO3 ceramics

    Science.gov (United States)

    Liu, Shujuan; Zhang, Lixue; Wang, Jiping; Shi, Xiujing; Zhao, Yingying; Zhang, Dawei

    2016-12-01

    In this work, we report a rapid stability phenomenon of ferroelectric polarization in the Ca, Ce hybrid doped BaTiO3 ceramics (BCaxT+BTCe8) (x = 10, 20, 24, 30 mol%) prepared by separate doping Ca2+ and Ce4+ ions. Double hysteresis loops are identified in the aged BCaxT+BTCe8 samples; meanwhile, the polarization of these loops present a rapid decrease within very short aging time (about 1 h), and then the polarization remains almost unchanged over the followed ~1000 h. This phenomenon is not reported in previous researches. Raman scattering spectrum indicates that oxygen vacancies are generated because of Ca2+ ions entering into Ti sites partly in the BCaxT+BTCe8 samples, and then the oxygen vacancies are quantitatively characterized by half of the Ce3+ content through the XPS test. The emergence of the aging phenomenon is explained through the defect dipole reorientation mechanism. The larger radius of Ca2+ ions is further discussed as a possible reason for the rapid stability phenomenon of ferroelectric polarization. It may provide an effective design method from the viewpoint of the ionic radius to accelerate polarization stability, and thus to facilitate the possible practical applications of the aging effect.

  19. Comparative dielectric studies of nanostructured BaTiO{sub 3}, CaCu{sub 3}Ti{sub 4}O{sub 12} and 0.5BaTiO{sub 3}⋅ 0.5CaCu{sub 3}Ti{sub 4}O{sub 12} nano-composites synthesized by modified sol–gel and solid state methods

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Laxman [Department of Chemistry, University of Ulsan, 93 Daehak-ro Nam-gu, Ulsan 680-749 (Korea, Republic of); Rai, Uma Shanker [Department of Chemistry, Centre of Advanced Study, Faculty of Science, Banaras Hindu University, Varanasi 221005, U.P. (India); Mandal, Kam Deo [Department of Chemistry, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005, U.P. (India); Sin, Byung Cheol; Lee, Hyung-il [Department of Chemistry, University of Ulsan, 93 Daehak-ro Nam-gu, Ulsan 680-749 (Korea, Republic of); Chung, Hoeil [Department of Chemistry, Hanyang University, Haengdang-dong 17, Seongdong-Gu, Seoul 133-791 (Korea, Republic of); Lee, Youngil, E-mail: nmryil@ulsan.ac.kr [Department of Chemistry, University of Ulsan, 93 Daehak-ro Nam-gu, Ulsan 680-749 (Korea, Republic of)

    2014-10-15

    BaTiO{sub 3} (BTO), CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) and 0.5BaTiO{sub 3}·0.5CaCu{sub 3}Ti{sub 4}O{sub 12} (BTO–CCTO), as a new nano-composite ceramic, were successfully designed and fabricated by a semi-wet gel route and a modified solid state method. The dielectric properties of the BTO–CCTO ceramic were compared to those of the BTO and CCTO ceramics at lower sintering temperatures and durations. The X-ray diffraction analysis revealed that the BTO and CCTO ceramics form a single crystalline phase and the average crystalline sizes calculated from X-ray diffraction data were in the range of 40–65 nm. The particle sizes of the BTO, CCTO, and BTO–CCTO ceramics obtained from transmission electron microscopy images were in the ranges of 40–65 nm, 80–110 nm, and 70–95 nm, respectively. The phase composition and microstructure were studied by X-ray diffraction and scanning electron microscopy. The energy dispersive X-ray results demonstrated the purity and stoichiometry of the BTO–CCTO nano-composite. The grain sizes of the BTO, CCTO and BTO–CCTO ceramics were found to be in the ranges of 500 nm–1 μm, 4–24 μm, and 250 nm–4 μm, respectively. The AC conductivity as a function of frequency confirmed the semiconducting nature of all of the ceramics and obeyed the Jonscher's power law. The impedance spectrum measurement result showed that the CCTO ceramic possessed an exceptional grain boundary resistance, which supports the internal barrier layer capacitance (IBLC) mechanism present in this ceramic and is responsible for the high ε{sub r} values. - Highlights: • Nanostructured BaTiO{sub 3}, CaCu{sub 3}Ti{sub 4}O{sub 12}, and 0.5BaTiO{sub 3}⋅ 0.5CaCu{sub 3}Ti{sub 4}O{sub 12} have been synthesized. • XRD and TEM analysis confirmed the formation of nanoparticles, 40–65 and 50–90 nm. • Impedance analysis shows high grain-boundary resistance present in CCTO ceramic. • AC conductivity as a function of frequency confirms the

  20. Photocatalytic reduction of CO{sub 2} with H{sub 2}O using perovskite Ca{sub x}Ti{sub y}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Byeong Sub; Kang, Misook, E-mail: mskang@ynu.ac.kr

    2015-05-15

    Highlights: • Ca{sub x}Ti{sub y}O{sub 3} was synthesized using a hydrothermal method. • The photocatalytic activity was measured by the reduction of CO{sub 2} to CH{sub 4}. • The yield of methane production was 17 μmol/g{sub cat} using Ca{sub 1.00}-Ti{sub 1.00}. - Abstract: This study is focused on the photoreduction of CO{sub 2} into CH{sub 4} using Ca{sub x}Ti{sub y}O{sub 3} perovskite nanoparticles. Ca{sub x}Ti{sub y}O{sub 3} nanoparticles were successfully synthesized by a hydrothermal method. The structure and property of Ca{sub x}Ti{sub y}O{sub 3} were characterized using XRD, UV–vis, PL, and BET techniques. The photoreduction of CO{sub 2} was performed with UV-lamp (6 W cm{sup −2}) irradiation. The gas products were analyzed in a gas chromatograph equipped with FID and TCD detectors. The methane formation rate from CO{sub 2} and H{sub 2}O was 17 μmol/g for 7 h using 0.2 g of Ca{sub 1.00}Ti{sub 1.00}O{sub 3}.

  1. Interplay of the strain and microstructure in ferroelectric epitaxial CaTiO3 Films

    Science.gov (United States)

    He, Qian; Liang, Qiao; Biegalski, Michael; Borisevich, Albina

    2014-03-01

    CaTiO3 (CTO) was predicted to become ferroelectric under lattice strain. However, other factors such as oxygen octahedral tilts or microstructural details can play a role. In this work, two 20 nm CTO films were grown on LSAT and NGO by PLD. They both show ferroelectricity, with Tc near 140 K on LSAT and near 70 K on NGO, and the remnant polarization at 10K of 5 and 2 μC/cm, respectively. This is surprising given that the strain of CTO on both substrates is similar. AC-STEM shows two major differences in microstructure between two CTO films: Firstly, the first few nm of CTO on NGO show perfect epitaxial growth, and after that grains start to develop, but the c-axis of CTO remains aligned with the c-axis of NGO, suggesting the presence of 180° grain boundaries only. However for CTO/LSAT, grains begin to develop at the interface and their c-axes have two possible orientations, resulting in both 180° and 90° grain boundaries. These grain boundaries are either dislocations or ferroelastic twins. Secondly, the octahedral tilt behavior at the film/substrate interface is different: CTO/LSAT has a 5-6 unit cell transition region from the untilted LSAT to the tilted CTO, which is not the case in CTO/NGO. The connection between the microstructure, substrate strain and connections to the ferroelectric properties will be discussed in detail. Research at ORNL supported by the MSE Division, BES, U.S. DOE, and through a user project supported by ORNL's CNMS, which is also sponsored by BES, U.S. DOE.

  2. Dissolution and diffusion of TiO2 in the CaO-Al2O3-SiO2 slag

    Institute of Scientific and Technical Information of China (English)

    Zhong-shan Ren; Xiao-jun Hu; Xin-mei Hou; Xiang-xin Xue; Kuo-chih Chou

    2014-01-01

    The dissolution of TiO2 in the CaO-Al2O3-SiO2 slag under static conditions was studied in the temperature range from 1643 K to 1703 K. After TiO2 dissolved, the microstructure of the interface between TiO2 and the slag was observed by scanning electron microscopy, and the concentration profiles of Ti4+and other ions across the TiO2/slag interfaces were analyzed by energy-dispersive X-ray spectroscopy. On the basis of these results, the dissolution behavior of TiO2 was evaluated, and the diffusivity of Ti4+in the bulk slag was estimated. Ac-cording to the Stokes-Einstein relation, the viscosity calculated by a previously reported model gave a diffusivity of Ti4+ions greater than that estimated by the concentration profiles of Ti4+ions. The mechanism of TiO2 dissolution in the CaO-Al2O3-SiO2 slag is discussed in de-tail.

  3. Analysis of the normal optical, Michel and molecular potentials on the $^{40}$Ca($^6$Li, d)$^{44}$ Ti reaction

    Indian Academy of Sciences (India)

    MAZUMDER UTTAM K; SOMADDER ANOCK; HOQUE ENAMUL; HAQUE YASMEEN; DAS SUSANTA K; SEN GUPTA H M

    2016-06-01

    Full finite-range (FFR) distorted-wave Born approximation (DWBA) method has been applied to analyse the angular distributions of cross-sections of the $^{40}$Ca($^{6}$Li, d)$^{44}$Ti reaction at 28 MeV incident energy for the 22 transitions involving both the bound and unbound states of $^{44}$Ti byusing the normal optical, Michel and molecular potentials. The extracted spectroscopic factors for the three optical potentials are compared with those of some previous studies of zero-range (ZR) calculations of the$^{40}$Ca($^{6}$Li, d)$^{44}$Ti reaction using the normal optical potential. The $\\chi^{2}$ values of all the levels are obtained for the three optical potentials to estimate the quality of the fits. Molecular and Michel potentials have been used for the first time to analyse the four-nucleon transfer reaction and it seems that the molecular potential fits the experimental data more satisfactorily for some of the states than the normal optical and Michel potentials.

  4. Preparation and properties of CaTiO3 ∶ Zn nanoparticles based on sol-gel method%CaTiO3∶Zn纳米粉体的溶胶凝胶法制备及性能研究

    Institute of Scientific and Technical Information of China (English)

    黄万群; 张启龙; 杨辉; 申乾宏

    2012-01-01

    采用溶胶凝胶法制备了CaTiO3∶Zn纳米粉体,研究了所制粉体的微观结构及性能.结果表明,所制粉体粒径约50 nm,主晶相为CaTiO3,Zn以Zn2TiO4形式存在于晶相中.1 150℃下烧结所得CaTiO3∶Zn纳米粉体性能较优:比固相法的烧结温度降低约250℃,相对介电常数εr=155,品质因数Q·f提高至6 633 GHz.%Nano-sized CaTiO3:Zn particles were successfully synthesized through sol-gel technique. The microstructure and other properties of the prepared nano particles were investigated. The average particle size of the CaTiO3: Zn powders calculated from TEM micrograph is about 50 nm. CaTiO3 is formed as the 'major phase, and the added Zn exists as Zn2TiO4 phase. The CaTiO3:Zn ceramics can be well sintered at 1 150 ℃, about 250 ℃ lower than those of ceramics obtained by conventional solid state method. The sintered CaTiO3:Zn ceramics possess a εr of 155, and a Q '/value of 6633 GHz which is greatly improved.

  5. Magnetic structure of CeScSi-type Tb {sub x}Er{sub 1-x}Ti{sub 0.85}Mo{sub 0.15}Ge compounds (x = 0, ?, 1)

    Energy Technology Data Exchange (ETDEWEB)

    Morozkin, A.V. [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, Moscow GSP-2 119992 (Russian Federation)]. E-mail: morozkin@general.chem.msu.ru; Nirmala, R. [Tata Institute of Fundamental Research, Mumbai 400005 (India); Halich, K. [Laboratoire de Chimie des metaux de transition, UMR 7513, Institut Le Bel, Universite Louis Pasteur, Strasbourg (France); Malik, S.K. [Tata Institute of Fundamental Research, Mumbai 400005 (India); Welter, R. [Laboratoire de Chimie des metaux de transition, UMR 7513, Institut Le Bel, Universite Louis Pasteur, Strasbourg (France)

    2005-04-19

    Magnetization and neutron diffraction studies have been carried out on CeScSi-type Tb {sub x}Er{sub 1-x}Ti{sub 0.85}Mo{sub 0.15}Ge compounds (space group I4/mmm, no. 139). These compounds demonstrate ferromagnetic collinear 1 (FC1), ferromagnetic collinear 2 (FC2) and ferromagnetic non-collinear 1 (FNC1) types of ordering. Below T {sub FC1} = 131 K for Tb{sub 0.25}Er{sub 0.75}Ti{sub 0.85}Mo{sub 0.15}Ge and T {sub FC1} = 194 K for Tb{sub 0.5}Er{sub 0.5}Ti{sub 0.85}Mo{sub 0.15}Ge the magnetic structure of these compounds consists of ferromagnetic (0 0 2) rare earth double layers with magnetic moments of rare earth atoms the [0, 0, M {sub z}]. Below T {sub FC2} = 242 K for Tb{sub 0.75}Er{sub 0.25}Ti{sub 0.85}Mo{sub 0.15}Ge and T {sub FC2} = 280 K for TbTi{sub 0.85}Mo{sub 0.15}Ge the magnetic structure of these compounds consists of ferromagnetic (0 0 1) layers with magnetic moments of rare earth atoms the [M {sub x}, 0, M {sub z}]. Below T {sub FNC1} = 63 K for ErTi{sub 0.85}Mo{sub 0.15}Ge, T {sub FNC1} = 14 K for Tb{sub 0.5}Er{sub 0.5}Ti{sub 0.85}Mo{sub 0.15}Ge, T {sub FNC1} = 29 K for Tb{sub 0.25}Er{sub 0.75}Ti{sub 0.85}Mo{sub 0.15}Ge and T {sub FNC1} = 75 K for TbTi{sub 0.85}Mo{sub 0.15}Ge the magnetic structure of these compounds consists of ferromagnetic (0 0 2) layers, but the magnetic moments of R atoms in the neighbouring layers are non-collinear.

  6. Microwave dielectric properties of CaCu3Ti4O12-Al2O3 composite

    Science.gov (United States)

    Rahman, Mohd Fariz Ab; Abu, Mohamad Johari; Karim, Saniah Ab; Zaman, Rosyaini Afindi; Ain, Mohd Fadzil; Ahmad, Zainal Arifin; Mohamed, Julie Juliewatty

    2016-07-01

    (1-x)CaCu3Ti4O12 + (x)Al2O3 composite (0 ≤ x ≤0.25) was prepared via conventional solid-state reaction method. The fabrication of sample was started with synthesizing stoichiometric CCTO from CaCO3, CuO and TiO2 powders, then wet-mixed in deionized water for 24 h. The process was continued with calcined CCTO powder at 900 °C for 12 h before sintered at 1040 °C for 10 h. Next, the calcined CCTO powder with different amount of Al2O3 were mixed for 24 h, then palletized and sintered at 1040 °C for 10. X-ray diffraction analysis on the sintered samples showed that CCTO powder was in a single phase, meanwhile the trace of secondary peaks which belong to CaAl2O4 and Corundum (Al2O3) could be observed in the other samples Scanning electron microscopy analysis showed that the grain size of the sample is firstly increased with addition of Al2O3 (x = 0.01), then become smaller with the x > 0.01. Microwave dielectric properties showed that the addition of Al2O3 (x = 0.01) was remarkably reduced the dielectric loss while slightly increased the dielectric permittivity. However, further addition of Al2O3 was reduced both dielectric loss and permittivity at least for an order of magnitude.

  7. Study of the electronic structure and half-metallicity of CaMnO3/BaTiO3 superlattice

    Science.gov (United States)

    Wang, Kai; Jiang, Wei; Chen, Jun-Nan; Huang, Jian-Qi

    2016-09-01

    In this paper, the electronic structure, magnetic properties and half-metallicity of the CaMnO3/BaTiO3 superlattice are investigated by employing the first-principle calculation based on density functional theory within the GGA or GGA + U exchange-correlation functional. The CaMnO3/BaTiO3 superlattice is constructed by the cubic CaMnO3 and the tetragonal ferroelectric BaTiO3 growing alternately along (0 0 1) direction. The cubic CaMnO3 presents a robust half-metallicity and a metastable ferromagnetic phase. Its magnetic moment is an integral number of 3.000 μB per unit cell. However, the CaMnO3/BaTiO3 superlattice has a stable ferromagnetic phase, for which the magnetic moment is 12.000 μB per unit cell. It also retains the robust half-metallicity which mainly results from the strong hybridization between Mn and O atoms. The results show that the constructed CaMnO3/BaTiO3 superlattice exhibits superior magnetoelectric properties. It may provide a theoretical reference for the design and preparation of new multiferroic materials.

  8. Preparation and characterizations of Ba{sub 0.8}Ca{sub 0.2}TiO{sub 3} by complex polymerization method (CPM)

    Energy Technology Data Exchange (ETDEWEB)

    Motta, F.V. [Laboratorio Interdisciplinar de Eletroquimica e Ceramica, CMDMC, Departamento de Quimica, Universidade Federal de Sao Carlos, 13565-905 Sao Carlos, SP (Brazil)], E-mail: fabiana@liec.ufscar.br; Marques, A.P.A. [Laboratorio de Analise Termica e Materiais, Departamento de Quimica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Escote, M.T. [CMDMC, LIEC, Instituto de Quimica, Universidade Estadual Paulista, 14801-907 Araraquara, SP (Brazil); Melo, D.M.A. [Laboratorio de Analise Termica e Materiais, Departamento de Quimica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Ferreira, A.G. [Laboratorio de Ressonancia Magnetica Nuclear, Departamento de Quimica, Universidade Federal de Sao Carlos, 13565-905 Sao Carlos, SP (Brazil); Longo, E. [CMDMC, LIEC, Instituto de Quimica, Universidade Estadual Paulista, 14801-907 Araraquara, SP (Brazil); Leite, E.R. [Laboratorio Interdisciplinar de Eletroquimica e Ceramica, CMDMC, Departamento de Quimica, Universidade Federal de Sao Carlos, 13565-905 Sao Carlos, SP (Brazil); Varela, J.A. [CMDMC, LIEC, Instituto de Quimica, Universidade Estadual Paulista, 14801-907 Araraquara, SP (Brazil)

    2008-10-06

    Ba{sub 0.8}Ca{sub 0.2}TiO{sub 3} (BCT) was prepared by the complex polymerization method (CPM) using Ba{sub 0.8}Ca{sub 0.2}CO{sub 3} and [Ti[OCH(CH{sub 3}){sub 2}]{sub 4} as starting materials. The powders were crystallized at several temperatures from 400 to 1200 deg. C using different times (from 1 to 8 h). The phase evolution and the physical properties were characterized by X-ray diffraction, Raman and IR spectroscopy. Such results indicate that the precursor Ba{sub 0.8}Ca{sub 0.2}CO{sub 3} used in the synthesis of Ba{sub 0.8}Ca{sub 0.2}TiO{sub 3} promotes an effective complexation of the ions Ca{sup 2+} in the matrix of BaTiO{sub 3}. After heat treatment for 2 h at 600 deg. C the phase BCT was obtained with absence of the CaTiO{sub 3} or BaCO{sub 3} phases. The CPM is an efficient method in the synthesis of the BCT, using small reaction time and low temperature and cost for the preparation of these powders.

  9. Polyimide/nanosized CaCu3Ti4O12 functional hybrid films with high dielectric permittivity

    Science.gov (United States)

    Yang, Yang; Zhu, Ben-Peng; Lu, Zhi-Hong; Wang, Zi-Yu; Fei, Chun-Long; Yin, Di; Xiong, Rui; Shi, Jing; Chi, Qing-Guo; Lei, Qing-Quan

    2013-01-01

    This work reports the high dielectric permittivity of polyimide (PI) embedded with CaCu3Ti4O12 (CCTO) nanoparticles. The dielectric behavior has been investigated over a frequency of 100 Hz-1 MHz. High dielectric permittivity (ɛ = 171) and low dielectric loss (tan δ = 0.45) at 100 Hz have been observed near the percolation threshold. The experimental results fit well with the Percolation theory. We suggest that the high dielectric permittivity originates from the large interface area and the remarkable Maxwell-Wagner-Sillars effect at percolation in which nomadic charge carriers are blocked at internal interfaces between CCTO nanoparticles and the polyimide matrix.

  10. Trapping of oxygen vacancies on twin walls of CaTiO sub 3 : a computer simulation study

    CERN Document Server

    Calleja, M; Salje, E K H

    2003-01-01

    We have studied the atomic structure of [001] 90 deg. rotation twin walls in orthorhombic CaTiO sub 3 (symmetry Pbnm) at low temperature (10 K) and their effects on oxygen vacancies. The wall thickness was found to be 2.3 nm at T || T sub c and it was found that it is energetically favourable for such vacancies to reside in the wall, particularly when bridging titania ions in the (001) plane. The binding energy of an oxygen vacancy in the wall with respect to the bulk is calculated to be <= 1.2 eV.

  11. Trapping of oxygen vacancies on twin walls of CaTiO{sub 3}: a computer simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Calleja, Mark; Dove, Martin T; Salje, Ekhard K H [Mineral Physics Group, Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ (United Kingdom)

    2003-04-16

    We have studied the atomic structure of [001] 90 deg. rotation twin walls in orthorhombic CaTiO{sub 3} (symmetry Pbnm) at low temperature (10 K) and their effects on oxygen vacancies. The wall thickness was found to be 2.3 nm at T || T{sub c} and it was found that it is energetically favourable for such vacancies to reside in the wall, particularly when bridging titania ions in the (001) plane. The binding energy of an oxygen vacancy in the wall with respect to the bulk is calculated to be {<=} 1.2 eV.

  12. Injury-Reduction Effectiveness of Prescribing Running Shoes Based on Plantar Shape in Marine Corps Basic Training, San Diego, CA, and Parris Island, SC

    Science.gov (United States)

    2007-10-01

    San Diego, CA: Carol Macera, Mitchell Rauh, and Richard Shaffer. Additional thanks are due to James Reading from MCRD, San Diego, CA. REPORT...Orthopedic and Sports Physical Therapy, 30:21-28. 40. Brody D.M. 1980. Running injuries. CIBA Clinical Symposia, 32:1-36. 41. James S.L...kappa-B in aveolar macrophages stimulated with TLR2 and TLR4 angonists. Journal of Immunology, 179:6097-6106. 131. McCrea K.A., Ensor J.E., Nall K

  13. Ab-initio study of the magnetism, structure and spin dependent electronic states of Ti substituted MO (M = Mg, Ca, Sr)

    Energy Technology Data Exchange (ETDEWEB)

    Jaiganesh, G., E-mail: jaiganesh@igcar.gov.in; Jaya, S. Mathi [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam - 603102 (India)

    2015-06-24

    The magnetism, structure and spin polarized electronic structure of Ti substituted MO (M = Mg, Ca, Sr) are studied using the ab-initio techniques within the framework of the density functional theory. Appropriately constructed supercell along with the full structural optimization of these cells is used for studying the influence of Ti substitution on the magnetism and electronic structure of these compounds. We find from our calculations that the Ti substituted MO compounds energetically favor magnetically ordered state. The Ti concentration is found to be important in deciding the magnetic order and we have observed antiferromagnetic order for the Ti concentration of 0.25. The Ti substituted MO compounds are thus an interesting class of materials that deserve further studies.

  14. N = 3 - 3 Transitions of Ne-like Ions in the Iron Group, Especially Ca(10+) and Ti(12+)

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, Y; Encarnacion, J L; Trabert, E

    2008-10-09

    The Ti XIII 2s{sup 2}2p{sup 5}3l-3l{prime} and 2s2p{sup 6}3l-3l{prime} transitions that have been discussed previously on the basis of beam-foil spectra and laser-produced plasmas in comparison to semi-empirically scaled computations have now been treated by accurate ab initio Multi-reference Moller-Plesset calculations. While most 2s{sup 2}2p{sup 5}3l-3l{prime} line identifications are supported by the new calculations, the 2s2p{sup 6}3l-3l{prime} transition arrays are revised. Theoretical level positions are given for all elements from Ca through Fe. The quality of the calculation is demonstrated on the beam-foil spectra of Ca.

  15. Magnetic properties of (SrFe12O19) x (CaCu3Ti4O12)1- x composites

    Science.gov (United States)

    Eremina, R. M.; Sharipov, K. R.; Yatsyk, I. V.; Lyadov, N. M.; Gilmutdinov, I. F.; Kiiamov, A. G.; Kabirov, Yu. V.; Gavrilyachenko, V. G.; Chupakhina, T. I.

    2016-07-01

    New composite materials (SrFe12O19) x (CaCu3Ti4O12)1- x ( x = 0, 0.05, 1) have been synthesized. Their magnetic properties are studied in the temperature range 5-300 K using the magnetic resonance and magnetometry methods. It is found that strontium hexaferrite microinclusions in the (SrFe12O19)0.05(CaCu3Ti4O12)0.95 composite "magnetize" CaCu3Ti4O12 at temperatures from 300 to 200 K, forming a ferrimagnetic particle near the SrFe12O19 "core." The magnetic resonance line below 200 K splits into two lines corresponding to SrFe12O19 and CaCu3Ti4O12. The core effect decoration is manifested in the increase in the Curie-Weiss temperature from 25 K in CaCu3Ti4O12 without the doping ceramics to 80 K in the composite with 5% of SrFe12O19.

  16. Phase evolution studies in CaZrTi2O7-RE2Ti2O7 (RE = Nd3+, Sm3+) system: Futuristic ceramic host matrices for nuclear waste immobilization

    Science.gov (United States)

    Jafar, M.; Achary, S. N.; Tyagi, A. K.

    2014-04-01

    Series of compositions with general stoichiometry as Ca1-xZr1-xRE2xTi2O7 (RE = Nd3+, Sm3+) were prepared by solid state reaction and characterized by powder x-ray diffraction technique to unravel the phase fields in the title systems. The phase fields in CaZrTi2O7-Nd2Ti2O7 and CaZrTi2O7-Sm2Ti2O7 systems differed significantly at the rareearth rich regions. The common phase fields like zirconolite-2M, zirconolite-4M, cubic perovskite are observed at the zirconolite rich regions of both systems. Depending on the structure of RE2Ti2O7 phase, the cubic pyrochlore or monoclinic RE2Ti2O7 phases are observed in the studied system. The observed phase fields in these two systems indicate ionic radius of the rare-earth ion has a dominating role in the phase relations. Further details of the phases and their homogeneity are explained in the text of the manuscript.

  17. Continuous cross-over from ferroelectric to relaxor state and piezoelectric properties of BaTiO{sub 3}-BaZrO{sub 3}-CaTiO{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Benabdallah, F.; Veber, P., E-mail: veber@icmcb-bordeaux.cnrs.fr; Prakasam, M.; Viraphong, O.; Maglione, M. [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Université Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France); Shimamura, K. [National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2014-04-14

    Optimal properties like piezoelectricity can be found in polarizable materials for which the structure changes sharply under small composition variations in the vicinity of their morphotropic phase boundary or the triple point in their isobaric temperature-composition phase diagram. In the latter, lead-free (Ba{sub 0.850}Ca{sub 0.150})(Ti{sub 0.900}Zr{sub 0.100})O{sub 3} ceramics exhibit outstanding piezoelectric coefficients. For the first time, we report the growth of piezoelectric lead-free single crystals in the BaTiO{sub 3}-BaZrO{sub 3}-CaTiO{sub 3} pseudo-ternary system. The stoichiometry control in the CaO-BaO-TiO{sub 2}-ZrO{sub 2} solid solution led to single crystals with various compositions ranging from (Ba{sub 0.857}Ca{sub 0.143})(Ti{sub 0.928}Zr{sub 0.072})O{sub 3} to (Ba{sub 0.953}Ca{sub 0.047})(Ti{sub 0.427}Zr{sub 0.573})O{sub 3}. We evidenced a continuous cross-over from a ferroelectric state at high titanium content to a relaxor one on increasing the zirconium content. Such a property tuning is rather seldom observed in lead-free ferroelectrics and confirms what was already reported for ceramics. Single crystal with (Ba{sub 0.838}Ca{sub 0.162})(Ti{sub 0.854}Zr{sub 0.146})O{sub 3} composition, which has been grown and oriented along [001] crystallographic direction, displayed electromechanical coefficients d{sub 31} and k{sub 31} of 93 pC.N{sup −1} and 0.18, respectively, near the room temperature (T = 305 K)

  18. Afterglow characteristics of CaTiO{sub 3}: Pr{sup 3+} prepared by solar furnace

    Energy Technology Data Exchange (ETDEWEB)

    Katayama, Yumiko; Tanabe, Setsuhisa, E-mail: yumiko@h05ktym.mbox.media.kyoto-u.ac.jp [Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-nihonmatsu-cho, Sakyo-ku, Kyoto, 606-8501 (Japan)

    2011-05-15

    We have prepared polycrystalline CaTiO{sub 3}: Pr{sup 3+} showing long-lasting phosphorescence by melting method using a solar furnace. Emission, excitation spectra, phosphorescence decay and thermoluminescence were compared with samples prepared by conventional solid-state reaction in conventional electric furnace (EF) at 1200 deg. C, 5 h in air. The color of the sample prepared by solar furnace (SF-AM) was dark brownish. After heat treatment at 800deg. C, 5h in air atmosphere, a decolorized sample (SF-HT) was obtained. All samples showed Pr{sup 3+}:{sup 1}D{sub 2} {yields} {sup 3}H{sub 4} fluorescence at 613 nm and corresponding afterglow phosphorescence. The SF-AM and SF-HT showed much higher PLE intensity of Pr{sup 3+}:{sup 3}P{sub J} bands in blue region than EF. CaTiO{sub 3}:Pr{sup 3+} made by a solar furnace has a potential to be a red afterglow phosphor even under visible excitation.

  19. Investigation of the Size Effect on the Giant Dielectric Constant of CaCu3Ti4O12 Ceramic

    Institute of Scientific and Technical Information of China (English)

    陈恺; 李伟; 刘云飞; 包鹏; 吕笑梅; 朱劲松

    2004-01-01

    Cubic perovskite-related ceramic CaCu3Ti4O12 has a very high dielectric constant larger than 10000 in the kilohertz frequency region. It is almost constant in the 100-600 K region. The ceramic compounds were prepared by conventional solid-state reaction at different sintering temperatures 1040 ℃(C04), 1060 ℃(C06), 1080 ℃(C08),and 1100 ℃(C10). Impedance spectroscopy on Ca Cus Ti4O12 ceramics demonstrates that they are electrically heterogeneous and consist of semi-conducting grains with insulating grain boundaries. It is shown that C06 is the most suitable one for device applications. Surface observation and analysis of the grain-boundary-grained structure were carried out by using scanning electron microscopy, which confirms that the samples have clearly different crystal grain sizes and C06 has a larger grain size of about 20 μm. Compared to the dielectric relaxation spectroscopy, the mechanical relaxation spectroscopy on C06 was performed and a mechanical loss peak was found, which was attributed to the thermally activated behaviour being immanent in the grains.

  20. Improved structure stability, optical and magnetic properties of Ca and Ti co-substituted BiFeO3 nanoparticles

    Science.gov (United States)

    Kumar, Vijay; Singh, Satyendra

    2016-11-01

    We report the optical and magnetic properties of single-crystalline Ca and Ti co-substituted bismuth ferrite, Bi1-xCaxFe1-xTixO3, nanoparticles, synthesized by a facile sol-gel methodology in the compositional range wherein 0 ≤ x ≤ 0.25. X-ray diffraction (XRD) and transmission electron microscopy (TEM) investigations show that all samples possess a rhombohedrally distorted perovskite structure with space group R3c. Ca and Ti co-substitution controls the formation of secondary phases and improved the stability of perovskite phase of BiFeO3. The average particle size was estimated by Williamson Hall plot, confirmed by TEM, and found to be about 59, 50, 46, 41, 40 and 38 nm of Bi1-xCaxFe1-xTixO3 for x = 0, 0.05, 0.10, 0.15, 0.20 and 0.25, respectively. The UV-vis absorption study reveal the strong absorption of visible light with a small optical band gap (1.77-2.25 eV) for 0 ≤ x ≤ 0.25 indicates a possibility of utilizing for photocatalytic activities. The magnetic study at room-temperature displays the improved magnetization and coercive field in Bi1-xCaxFe1-xTixO3 nanoparticles due to the release of the latent magnetization locked within the toroidal spin structure of BiFeO3.

  1. Ultra-low coercive field of improper ferroelectric Ca3Ti2O7 epitaxial thin films

    Science.gov (United States)

    Li, X.; Yang, L.; Li, C. F.; Liu, M. F.; Fan, Z.; Xie, Y. L.; Lu, C. L.; Lin, L.; Yan, Z. B.; Zhang, Z.; Dai, J. Y.; Liu, J.-M.; Cheong, S. W.

    2017-01-01

    Hybrid improper ferroelectrics have their electric polarization generated by two or more combined non-ferroelectric structural distortions, such as the rotation and tilting of Ti-O octahedral in the Ca3Ti2O7 (CTO) family. In this work, we prepare the high quality (010)-oriented CTO thin films on (110) SrTiO3 (STO) substrates by pulsed laser deposition. The good epitaxial growth of the CTO thin films on the substrates with the interfacial epitaxial relationship of [001]CTO//[001]STO and [100]CTO//[-110]STO is revealed. The in-plane ferroelectric hysteresis unveils an ultralow coercive field of ˜5 kV/cm even at low temperature, nearly two orders of magnitude lower than that of bulk CTO single crystals. The huge difference between the epitaxial thin films and bulk crystals is most likely due to the lattice imperfections in the thin films rather than substrate induced lattice strains, suggesting high sensitivity of the ferroelectric properties to lattice defects.

  2. Preparation and Characterization of Nanocrystalline Thin Films of Al2O3 or TiO2 Doped Scandia Stabilized Zirconia Solid Electrolytes%Al2O3或TiO2掺杂的ScSZ固体电解质纳米晶薄膜的制备及表征

    Institute of Scientific and Technical Information of China (English)

    张亚文; 杨宇; 金舒; 田曙坚; 李国宝; 贾江涛; 廖春生; 严纯华

    2001-01-01

    Dense,crack-free and uniform nanocrystalline (Al2O3)0.10(Sc2O3)0.08(ZrO2)0.82and (Sc2O3)0.125(TiO2)0.175(ZrO2)0.70 thin films with thickness of 0.31 μm and 0.36 μm respectively on Si(100) substrate,have been successfully prepared by a Sol\\|Gel spin coating method.Cubic nanocrystals can be obtained at relatively low sintering temperature with an average grain size of about 47 nm and 51 nm respectively.The aluminia-doped ScSZ thins film are the same dense as the ScSZ thin films.However,there are a small amount of pinholes found in the microstructure of the titania-doped ScSZ films.%利用溶胶-凝胶旋涂法,在单晶硅基片(100)上分别制得了厚度约为0.31 μm的(Al2O3)0.10(Sc2O3)0.08(ZrO2)0.82和0.36 μm的(Sc2O3)0.125(TiO2)0.175(ZrO2)0.70固体电解质纳米晶薄膜。烧结实验结果表明,两种薄膜均在650℃以上开始晶化,温度越高,晶化越完全,在800℃可完全晶化;所得纳米晶颗粒呈纯的萤石结构立方相;铝和钛掺杂的纳米晶颗粒的平均大小分别为47和51 nm。铝掺杂的薄膜非常均匀致密,然而,钛掺杂的薄膜存在少量微气孔。

  3. Dielectric properties, impedance analysis and modulus behavior of CaTiO{sub 3} ceramic prepared by solid state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Y.J., E-mail: yjeng_86@hotmail.com [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hassan, J., E-mail: jumiah@science.upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hashim, M., E-mail: mansor@science.upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2013-09-15

    Highlights: •A single phase orthorhombic CaTiO{sub 3} structure with sub-micron grains is produced. •The frequency exponent ‘s’ is temperature dependent and explained by CBH model. •The dielectric constant and loss tangent are frequency and temperature dependent. •The modulus plot reveals the presence of thermally activated dielectric relaxation. •Cole-cole plot reveals two primary relaxation processes exist in the sample. -- Abstract: Calcium titanate (CaTiO{sub 3}) with the general formula for perovskites, ABO{sub 3}, is of technological importance, particularly with regard to dielectric properties. In this work, CaTiO{sub 3} ceramic material was prepared by the conventional solid state reaction method. The dielectric properties, impedance characteristics and modulus behavior of the CaTiO{sub 3} ceramic material sintered at 1240 °C were investigated in the frequency range of 10{sup −2}–10{sup 6} Hz and temperature range of 100–250 °C. The XRD analysis of the sintered CaTiO{sub 3} shows that it is an orthorhombic structure with lattice parameters a = 5.4398 Å, b = 7.6417 Å, and c = 5.3830 Å. The FESEM micrograph shows a significant difference in grain size distribution ranging from 0.26 to 2.32 μm. The AC conductivity, σ{sub AC}, is found to increase with increasing temperature within the frequency range of 10{sup −2}–10{sup 6} Hz confirming the hopping of electrons to be the conduction mechanism. Due to the decreasing values of the frequency exponent s with increasing temperature, the results of the σ{sub AC} are discussed using the correlated barrier height (CBH) model. For dielectric studies, the dielectric constant, ε′ is found to decrease with increasing frequency. In the whole temperature range of 100–250 °C, high and low frequency plateau are observed. Each converges at high frequency (>10{sup 5} Hz) for all the temperatures. The frequency dependence of loss tangent, tan δ, decreases with rise in temperature, with the

  4. Probing charge transfer in a novel class of luminescent perovskite-based heterostructures composed of quantum dots bound to RE-activated CaTiO3 phosphors

    Science.gov (United States)

    Lewis, Crystal S.; Liu, Haiqing; Han, Jinkyu; Wang, Lei; Yue, Shiyu; Brennan, Nicholas A.; Wong, Stanislaus S.

    2016-01-01

    We report on the synthesis and structural characterization of novel semiconducting heterostructures composed of cadmium selenide (CdSe) quantum dots (QDs) attached onto the surfaces of novel high-surface area, porous rare-earth-ion doped alkaline earth titanate micron-scale spherical motifs, i.e. both Eu-doped and Pr-doped CaTiO3, composed of constituent, component nanoparticles. These unique metal oxide perovskite building blocks were created by a multi-pronged synthetic strategy involving molten salt and hydrothermal protocols. Subsequently, optical characterization of these heterostructures indicated a clear behavioral dependence of charge transfer in these systems upon a number of parameters such as the nature of the dopant, the reaction temperature, and particle size. Specifically, 2.7 nm diameter ligand-functionalized CdSe QDs were anchored onto sub-micron sized CaTiO3-based spherical assemblies, prepared by molten salt protocols. We found that both the Pr- and Eu-doped CaTiO3 displayed pronounced PL emissions, with maximum intensities observed using optimized lanthanide concentrations of 0.2 mol% and 6 mol%, respectively. Analogous experiments were performed on Eu-doped BaTiO3 and SrTiO3 motifs, but CaTiO3 still performed as the most effective host material amongst the three perovskite systems tested. Moreover, the ligand-capped CdSe QD-doped CaTiO3 heterostructures exhibited effective charge transfer between the two individual constituent nanoscale components, an assertion corroborated by the corresponding quenching of their measured PL signals.We report on the synthesis and structural characterization of novel semiconducting heterostructures composed of cadmium selenide (CdSe) quantum dots (QDs) attached onto the surfaces of novel high-surface area, porous rare-earth-ion doped alkaline earth titanate micron-scale spherical motifs, i.e. both Eu-doped and Pr-doped CaTiO3, composed of constituent, component nanoparticles. These unique metal oxide perovskite

  5. Shape Memory Characteristics of Ti(sub 49.5)Ni(sub 25)Pd(sub 25)Sc(sub 0.5) High-Temperature Shape Memory Alloy After Severe Plastic Deformation

    Science.gov (United States)

    Atli, K. C.; Karaman, I.; Noebe, R. D.; Garg, A.; Chumlyakov, Y. I.; Kireeva, I. V.

    2011-01-01

    A Ti(49.5)Ni25Pd25Sc(0.5) high-temperature shape memory alloy is thermomechanically processed to obtain enhanced shape-memory characteristics: in particular, dimensional stability upon repeated thermal cycles under constant loads. This is accomplished using severe plastic deformation via equal channel angular extrusion (ECAE) and post-processing annealing heat treatments. The results of the thermomechanical experiments reveal that the processed materials display enhanced shape memory response, exhibiting higher recoverable transformation and reduced irrecoverable strain levels upon thermal cycling compared with the unprocessed material. This improvement is attributed to the increased strength and resistance of the material against defect generation upon phase transformation as a result of the microstructural refinement due to the ECAE process, as supported by the electron microscopy observations.

  6. Density functional study of the stability and magnetic behaviour of Au{sub n}TM{sup +} clusters (TM=Au,Sc,Ti,V,Cr,Mn,Fe; 1{<=}n{<=}9)

    Energy Technology Data Exchange (ETDEWEB)

    Torres, M.B. [Dpto. de Matematicas y Computacion, Univ. de Burgos, Avda. de Cantabria s/n, 09006-Burgos (Spain); Fernandez, E.M.; Balbas, L.C. [Dpto. de Fisica Teorica, Univ. de Valladolid, Prado de la Magdalena s/n, 47011-Valladolid (Spain)

    2005-03-01

    We study the element- and size-dependent electron stability of Au{sub n}TM{sup +} clusters (TM=Sc,Ti,V,Cr,Mn,Fe,Au; 1{<=}n{<=}9) by means of first-principles density functional calculations. The interplay between the cluster atomic arrangements and their electronic and magnetic structure is investigated for the few lower energy isomeric-states in dependence of the TM-atom and its environment in the cluster. We explain the experimental magic-numbers, observed recently, as well as the trend of the impurity local magnetic moment in dependence with the size of the cluster and the position of the impurity in the host. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Effects of substitution of Sr for Ca on microstructure and dielectric properties of Ca4La2Ti5O17 microwave ceramics%Sr替代Ca对Ca4La2Ti5O17微波陶瓷的微结构和介电性能的影响

    Institute of Scientific and Technical Information of China (English)

    狄洁昌; 陈国华

    2012-01-01

    采用固相反应法制备了Ca4-xSrxLa2Ti5O17(x=0~3)微波介质陶瓷.研究了Sr替代Ca对Ca4La2Ti5O17陶瓷的相纯度、微观结构和介电性能的影响.结果表明,在替代范围内所有样品呈单相固溶体结构,晶格参数和晶胞体积随着x的增加而增大.Sr替代Ca抑制了陶瓷样品的晶粒生长.随着x增加,样品介电常数和谐振频率温度系数逐渐增加,而品质因数逐渐减小.该类材料有望用于微波介质负载天线.%Ca4-xSrxLa2Ti5O17(x=0-3) microwave dielectric ceramics were prepared by a solid-state reaction method. The effects of the substitution of Sr for Ca on the phase purity, microstructure and dielectric properties of Ca4La2Ti5O17 ceramics were investigated. The results show that all ceramic samples adopt the single phase solid solution structure within limits of substitution, and the lattice parameters and unit cell volume increase with the increase of x value. The substitution of Sr for Ca restrains the grain growth. With the increase of x value, the permittivity and temperature coefficient of resonant frequency gradually of samples increase while the quality factor decreases. It suggest that this material may be useful in the dielectrically loaded antennas in microwave frequency.

  8. Electrical and microstructural properties of CaTiO3-doped K1/2Na1/2NbO3-lead free ceramics

    Indian Academy of Sciences (India)

    L Ramajo; R Parra; M A Ramírez; M S Castro

    2011-10-01

    Microstructure, electrical properties and dielectric behaviour of K1/2Na1/2NbO3 (KNN) and CaTiO3- modified K1/2Na1/2NbO3 (CTO-KNN) systems, were investigated. Discs doped with 0 to 0.55% mol of CaTiO3 (CTO) were sintered at 1125°C for 2 h. Although minority phases were found in doped samples, CaTiO3 was not detected. It was also observed that CTO changed the microstructure and grain size of KNN drastically. Also, the Curie temperature and permittivity values decreased. Addition of CTO between 0.15 and 0.45 mol% decreases the density and dielectric values. Samples prepared with higher content of CTO than 0.45 mol% showed better electrical properties.

  9. Probing charge transfer in a novel class of luminescent perovskite-based heterostructures composed of quantum dots bound to RE-activated CaTiO3 phosphors.

    Science.gov (United States)

    Lewis, Crystal S; Liu, Haiqing; Han, Jinkyu; Wang, Lei; Yue, Shiyu; Brennan, Nicholas A; Wong, Stanislaus S

    2016-01-28

    We report on the synthesis and structural characterization of novel semiconducting heterostructures composed of cadmium selenide (CdSe) quantum dots (QDs) attached onto the surfaces of novel high-surface area, porous rare-earth-ion doped alkaline earth titanate micron-scale spherical motifs, i.e. both Eu-doped and Pr-doped CaTiO3, composed of constituent, component nanoparticles. These unique metal oxide perovskite building blocks were created by a multi-pronged synthetic strategy involving molten salt and hydrothermal protocols. Subsequently, optical characterization of these heterostructures indicated a clear behavioral dependence of charge transfer in these systems upon a number of parameters such as the nature of the dopant, the reaction temperature, and particle size. Specifically, 2.7 nm diameter ligand-functionalized CdSe QDs were anchored onto sub-micron sized CaTiO3-based spherical assemblies, prepared by molten salt protocols. We found that both the Pr- and Eu-doped CaTiO3 displayed pronounced PL emissions, with maximum intensities observed using optimized lanthanide concentrations of 0.2 mol% and 6 mol%, respectively. Analogous experiments were performed on Eu-doped BaTiO3 and SrTiO3 motifs, but CaTiO3 still performed as the most effective host material amongst the three perovskite systems tested. Moreover, the ligand-capped CdSe QD-doped CaTiO3 heterostructures exhibited effective charge transfer between the two individual constituent nanoscale components, an assertion corroborated by the corresponding quenching of their measured PL signals.

  10. SO2 Poisoning Behaviors of Ca-Mn/TiO2 Catalysts for Selective Catalytic Reduction of NO with NH3 at Low Temperature

    OpenAIRE

    Qingqing Tian; Hongfeng Liu; Weiyuan Yao; Yan Wang; Yue Liu; Zhongbiao Wu; Haiqiang Wang; Xiaole Weng

    2014-01-01

    The sulfur tolerance of Ca modified MnOx /TiO2 catalysts in low-temperature SCR process was investigated. Experimental results revealed that the durability of developed catalysts in the presence of SO2 could be improved by Ca modification. After being subjected to a range of analytical techniques, it was found that the surface Ca species could act as a SO2 trap by preferentially reacting with SO2 to form bulk-like CaSO4, inhibiting the sulfation of active phase. Furthermore, the introducti...

  11. Phase equilibria in CaO–B{sub 2}O{sub 3}–TiO{sub 2} system at 1373 K and 1473 K

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Qifeng, E-mail: shuqifeng@gmail.com [Department of Physical Chemistry, School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Zhen; Chou, Kuochih [Department of Physical Chemistry, School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2013-06-15

    Highlights: ► Phase equilibria in CaO–B{sub 2}O{sub 3}–TiO{sub 2} system at 1373 K and 1473 K were investigated using quenching method followed by XRD and SEM–EDS. ► Isothermal sections in CaO–B{sub 2}O{sub 3}–TiO{sub 2} system at 1373 K and 1473 K were experimentally constructed. ► The liquidus compositions of CaO–B{sub 2}O{sub 3}–TiO{sub 2} system at 1373 K and 1473 K were determined. -- Abstract: Phase equilibria in CaO–B{sub 2}O{sub 3}–TiO{sub 2} system at 1373 K and 1473 K were investigated using quenching method followed by X-ray diffraction and scanning electron microscopy (SEM) equipped with energy dispersive analysis (EDS). Isothermal sections in CaO–B{sub 2}O{sub 3}–TiO{sub 2} system at 1373 K and 1473 K were experimentally constructed. No ternary oxide compounds were found in this system. The liquidus composition of CaO–B{sub 2}O{sub 3}–TiO{sub 2} system at 1373 K and 1473 K were determined. The section at 1373 K contains one liquid region, three solid–liquid coexistence regions and five subsolid regions. The section at 1473 K contains one liquid region, five solid–liquid coexistence regions and three subsolidus regions.

  12. Dielectric and Magnetic Properties of (1-x) CaTiO3--xNi0.5Zn0.5Fe2O4 Composite Ceramics

    Institute of Scientific and Technical Information of China (English)

    CHEN Chen; LIU Yin; WANG Chuanchuang; ZHU Yanyan; CHENG Qian; YI Zhiguo

    2016-01-01

    (1-x)CaTiO3-xNi0.5Zn0.5Fe2O4 (0x 1.0) composite ceramics were synthesized by a conventional solid state reaction method. The phase formation, microstructure, and dielectric and magnetic properties were investigated by X-ray diffraction, scanning electron microscopy, precision impedance analysis, and vibrating sample magnetometry, respectively. The results indicate that the composite ceramics are composed of both perovskite phase CaTiO3 and spinel phase Ni0.5Zn0.5Fe2O4. The maximal relative density for 0.5CaTiO3-0.5Ni0.5Zn0.5Fe2O4 composite ceramics reaches 97.8%, as it has been sintered at the temperature of 1260℃ for 3 h. Dielectric constant and loss tangent of (1-x)CaTiO3-xNi0.5Zn0.5Fe2O4 composite ceramics show dispersion in the low frequency range. Their phase transition temperature of the dielectric constant shifts to lower temperatures with the increase of Ni0.5Zn0.5Fe2O4 content. This phenomenon is attributed to that the phase transition temperature of CaTiO3 is higher than that of Ni0.5Zn0.5Fe2O4. The saturation magnetization of (1-x) CaTiO3-xNi0.5Zn0.5Fe2O4 composite ceramics increases with the Ni0.5Zn0.5Fe2O4 ferrite content.

  13. Synthesis, Characterization and Properties of Ca5A2TiO12 (A=Nb, Ta) Ceramic Dielectric Materials for Applications in Microwave Telecommunication Systems

    Science.gov (United States)

    Bijumon, Pazhoor Varghese; Mohanan, Pezholil; Sebastian, Mailadil Thomas

    2002-06-01

    Microwave ceramic dielectric materials Ca5Nb2TiO12 and Ca5Ta2TiO12 have been prepared by a conventional solid-state ceramic process. The structure was studied by X-ray diffraction and the dielectric properties were characterized at microwave frequencies. The ceramics posses a relatively high dielectric constant, very low dielectric loss (Qu× f> 30000 GHz) and small temperature variation of resonant frequency. These materials are potential candidates for dielectric resonator applications in microwave integrated circuits.

  14. In vitro degradation, cytocompatibility and hemolysis tests of CaF2 doped TiO2-SiO2 composite coating on AZ31 alloy

    Science.gov (United States)

    Li, Bing; Chen, Yun; Huang, Wei; Yang, Wenzhong; Yin, Xiaoshuang; Liu, Ying

    2016-09-01

    In this study, a CaF2 doped TiO2-SiO2 composite coating was successfully coated onto AZ31 alloy by sol-gel method. Electrochemical tests, in vitro degradation, direct cellular experiment and hemolysis tests were conducted and the results showed that the CaF2 doped TiO2-SiO2 composite coating can not only improve the corrosion resistance, but also enhance the biocompatibility of AZ31 alloy. XRD, SEM and EDX were also performed to characterize the crystalline structures, morphologies and chemical compositions of the coatings.

  15. Structure and Characteristics of Oxide Films Containing Ca and P on Ti Substrate

    Institute of Scientific and Technical Information of China (English)

    Fu LIU; Fuping WANG; Tadao Shimizu; Kaoru Igarashi; Liancheng ZHAO

    2005-01-01

    The ceramic coating was formed by using microarc oxidation (MAO) in the electrolytic solution ofβ-Glycerophosphate sodium salt pentahydrate (β-GP) and calcium acetate (CA). The microstructure, phase structure and phase composition were investigated with scanning electron microscopy (SEM), atomic force microscope (AFM), energy dispersive X-ray microanalyser (EDX), X-ray photoelectron spectroscopy (XPS), electron probe micro analyzer (EPMA) and X-ray diffraction (XRD). Investigation of the chemical composition of the coating with EDX revealed that Ca and P of high concentration existed in oxide films. XRD patterns indicated that the oxide film was composed of only anatase at low voltage discharge, and that rutile peaks appear in addition to anatase peak with increasing MAO voltage. Despite the existence of Ca and P, compounds concerning Ca and P were not detected in the oxide film.

  16. Dielectrical behaviour of CaCu{sub 3}Ti{sub 4}O{sub 1}2 ceramics; Comportamiento dielectrico de ceramicos de CaCu{sub 3}Ti{sub 4}O{sub 1}2

    Energy Technology Data Exchange (ETDEWEB)

    Ramajo, L.; Reboredo, M. M.; Castro, M. S.

    2011-07-01

    In this work, CaCu{sub 3}Ti{sub 4}O{sub 1}2 (CCTO) ceramics were prepared by solid state reaction at 900 degree centigrade for 12 h and sintered at 1100 degree centigrade during 3 h. The main phase detected through X-ray diffraction (XRD) was CCTO. Also, by means of Raman spectroscopy, it was observed a secondary phase rich in CuO. A dielectric constant higher than 13.000{epsilon}{sub 0} was obtained by Impedance spectroscopy measurements in the range between 25 to 10{sup 6}Hz. The value could be explained by the effect of dipolar and space charge polarization processes. (Author) 27 refs.

  17. Influence of Compositions on the Dielectric Properties of CaBi4Ti4O15 Ceramics%组分影响CaBi4Ti4O15介电性能的研究

    Institute of Scientific and Technical Information of China (English)

    郑夏莲; 黄新友; 高春华

    2006-01-01

    采用正交设计试验法研究了配方对CaBi4Ti4O15(CBT)铁电陶瓷介电性能的影响,得到了影响CBT陶瓷介电性能的主次因素以及各因素水平影响其性能的趋势,进而得到了综合性能佳的CBT陶瓷.探讨了各组分对CBT陶瓷介电性能影响的机理,为CBT陶瓷材料的改性研究提供了依据.

  18. Photocatalytic characteristics for the nanocrystalline TiO{sub 2} on the Ag-doped CaAl{sub 2}O{sub 4}:(Eu,Nd) phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung-Sik, E-mail: jskim@uos.ac.kr; Sung, Hyun-Je; Kim, Bum-Joon

    2015-04-15

    Highlights: • The photocatalytic reactivity of the TiO{sub 2}-coated on the Ag-doped long-lasting phosphor (CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+}). • The photodecomposition of benzene gas under visible light irradiation. • The TiO{sub 2}-coated on the Ag-doped long-lasting phosphor showed much higher photocatalytic reactivity. • The light emitted from the long-lasting phosphors contributed to the photo generation of TiO{sub 2}. - Abstract: This study investigated the photocatalytic behavior of nanocrystalline TiO{sub 2} deposited on Ag-doped long-lasting phosphor (CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+}). The CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+} phosphor powders were prepared via conventional sintering using CaCO{sub 3}, Al{sub 2}O{sub 3}, Eu{sub 2}O{sub 3}, and Nd{sub 2}O{sub 3} as raw materials according to the appropriate molar ratios. Silver nanoparticles were loaded on the phosphor by mixing with an aqueous Ag-dispersion solution. Nanocrystalline TiO{sub 2} was deposited on Ag-doped CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+} powders via low-pressure chemical vapor deposition (LPCVD). The TiO{sub 2} coated on the phosphor was actively photo-reactive under irradiation with visible light and showed much faster benzene degradation than pure TiO{sub 2}, which is almost non-reactive. The coupling of TiO{sub 2} with phosphor may result in an energy band bending in the junction region, which then induces the TiO{sub 2} crystal at the interface to be photo-reactive under irradiation with visible light. In addition, the intermetallic compound of CaTiO{sub 3} that formed at the interface between TiO{sub 2} and the CaAl{sub 2}O{sub 4}:(Eu{sup 2+},Nd{sup 3+}) phosphor results in the formation of oxygen vacancies and additional electrons that promote the photodecomposition of benzene gas. The addition of Ag nanoparticles enhanced the photocatalytic reactivity of the TiO{sub 2}/CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+} phosphor. TiO{sub 2} on the Ag

  19. Investigation into the use of CaZrO{sub 3} as a facecoat material in the investment casting of TiAl alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, C., E-mail: c.yuan@bham.ac.uk [School of Metallurgy and Materials, The University of Birmingham, B152TT (United Kingdom); Cheng, X. [School of Metallurgy and Materials, The University of Birmingham, B152TT (United Kingdom); School of Material Science and Engineering, Beihang University, No, 37 Xueyuan Street, Haidian District, Beijing 100191 (China); Withey, P.A. [School of Metallurgy and Materials, The University of Birmingham, B152TT (United Kingdom); Rolls-Royce plc. (United Kingdom)

    2015-04-01

    Research was carried out to determine the interactions between the filler and stucco materials in CaZrO{sub 3} based facecoats during shell firing as well as between the facecoat and a TiAl alloy during the casting process. A ‘flash re-melting’ technique, which gives a similar heating profile to the actual investment casting process, was used to study the phase transformations in the shell moulds. The chemical inertness of the facecoat was then investigated using a sessile drop test using a Ti–45Al–2Nb–2Mn–0.2TiB alloy. In this study, the facecoat compositions and the interaction products between metal and shells were characterized using x-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A severe interaction was found between CaZrO{sub 3} filler and Al{sub 2}O{sub 3} stucco, which rapidly damaged the shell surface. As well as oxygen, zirconium and silicon ions from the shell moulds were also observed to penetrate into the TiAl metal to form (Ti, Zr){sub 5}(Al, Si){sub 3} phases in the metal/shell interfacial areas. - Highlights: • To determine the interactions between CaZrO{sub 3} filler and stucco materials during shell firing. • To study the reaction between the CaZrO{sub 3} facecoat and TiAl alloy during casting. • The Al{sub 2}O{sub 3} stucco can react with CaZrO{sub 3} filler to form (Zr, Ca)O{sub 2} and CaAl{sub x}O{sub y} at 1650 °C. • O, Zr and Si ions from the ceramic moulds were observed to penetrate into the TiAl metal. • The reaction products include (Ti, Zr){sub 5}(Al, Si){sub 3} and ZrAl{sub 2} phase with high Ti ions solid solution.

  20. Dielectric properties of poly(vinylidene fluoride/CaCu3Ti4O12 nanocrystal composite thick films

    Directory of Open Access Journals (Sweden)

    2010-10-01

    Full Text Available The poly(vinylidene fluoride/CaCu3Ti4O12 (CCTO nanocrystal composite films (thickness ≈85 µm with relatively high dielectric permittivity (90 at 100 Hz were prepared by the solution casting followed by spin coating technique. The structural, the microstructural and the dielectric properties of the composites were studied using X-ray diffraction, Scanning Electron Microscope, and Impedance analyzer respectively. The effective dielectric permittivity (εeff of the composite increased with increase in the volume fraction of CCTO at all the frequencies (100 Hz to 1 MHz under investigation. The room temperature dielectric permittivity which is around 90 at 100 Hz, has increased to about 290 at 125°C (100 Hz. These results may be exploited in the development of high energy density capacitors.

  1. Preparation of high dielectric constant thin films of CaCu3Ti4O12 by sol–gel

    Indian Academy of Sciences (India)

    Deepam Maurya; Devendra P Singh; D C Agrawal; Y N Mohapatra

    2008-02-01

    Preparation of sol–gel derived CaCu3Ti4O12 (CCTO) thin films using two different sols and their characterization including their dielectric response are reported. The properties of CCTO films depend heavily on solvents used to prepare the sols. Dielectric constant as high as ∼900 at 100 kHz could be obtained when acetic acid was used to prepare the sol; in contrast, use of hexanoic acid in the sol yielded films with a much lower dielectric constant. The variation in grain and grain boundary conductivities with temperature has been measured. Activation energies of 0.08 eV and 0.68 eV have been found for grain and grain boundary conduction, respectively.

  2. Electromagnetic behavior of radar absorbing materials based on Ca hexaferrite modified with Co-Ti ions and doped with La

    Directory of Open Access Journals (Sweden)

    Valdirene Aparecida da Silva

    2009-06-01

    Full Text Available Radar Absorbing Materials (RAM are compounds that absorb incidental electromagnetic radiation in tuned frequencies and dissipate it as heat. Its preparation involves the adequate processing of polymeric matrices filled with compounds that act as radar absorbing centers in the microwave range. This work shows the electromagnetic evaluation of RAM based on CoTi and La doped Ca hexaferrite. Vibrating Sample Magnetization analyses show that ion substitution promoted low values for the parameters of saturation magnetization (123.65 Am2/kg and coercive field (0.07 T indicating ferrite softening. RAM samples obtained using different hexaferrite concentrations (40-80 per cent, w/w show variations in complex permeability and permittivity parameters and also in the performance of incidental radiation attenuation. Microwave attenuation values between 40 and 98 per cent were obtained.

  3. Low-Temperature Sintering and Electromagnetic Properties of NiCuZn/CaTiO3 Composites

    Science.gov (United States)

    Yang, Haibo; Yang, Yanyan; Lin, Ying; Zhu, Jianfeng; Wang, Fen

    2012-04-01

    Dense CaTiO3/Ni0.37Cu0.20Zn0.43Fe1.92O3.88 (CTO/NiCuZn) composites were prepared by the conventional solid-state reaction method and sintered at 950°C. The phase compositions and surface morphologies of the composites were investigated using x-ray diffraction and scanning electron microscopy, respectively. The dielectric and magnetic properties of the composites were also investigated. The results show that the CTO/NiCuZn composites possess high dielectric constants and permeabilities, which can be used in high-frequency communications for capacitor-inductor integrating devices such as electromagnetic interference filters and antennas. With increasing NiCuZn concentration, the permeabilities of the CTO/NiCuZn composites increase, while the dielectric constants and cutoff frequencies decrease.

  4. Characterization of microstructures evolution on electrical responses of CaCu3Ti4O12 ceramics

    Directory of Open Access Journals (Sweden)

    Mohd Fariz Ab Rahman

    2016-07-01

    Full Text Available CaCu3Ti4O12 (CCTO ceramics was prepared by solid state method. The raw materials of CaCO3, CuO, and TiO2 were ball milled for 1 h. The mixed powders were calcined at 900 °C for 12 h. The phase formations of calcined powders were analyzed by using X-ray Diffraction (XRD. The calcined powders were pressed into pellet shape at 300 MPa and then were sintered at 1020, 1030 and 1040 °C for 10 h, respectively. The sintered samples were subjected to XRD, Scanning Electron Microscopy (SEM and Impedance Analyzer for phase formation, microstructural and dielectric measurement analysis respectively. XRD analysis shows the presence of CCTO and secondary phases for the calcined powders. The samples sintered at 1020 and 1040 °C show the formation of CCTO phase with trace of secondary phases while complete formation of CCTO single phase was obtained for the sample sintered at 1030 °C. SEM analysis shows the phenomena of abnormal grain growth for the samples sintered at 1020 and 1040 °C while fine grain was observed for the sample sintered at 1030 °C. Sample sintered at 1040 °C was the densest sample while the sample sintered at 1020 °C had the highest percent of porosity. The highest dielectric constant (∼3748 was achieved for samples sintered at 1040 °C while the lowest dielectric loss (∼0.025 was obtained for the samples sintered at 1020 °C. These results indicate that sintering temperatures effectively changed the properties of CCTO.

  5. Wideband and Narrowband Microwave Characteristics of Co/Ti-Substituted M-Type Ca-Hexagonal Ferrite

    Science.gov (United States)

    Singh, Charanjeet; Bindra Narang, S.

    2017-02-01

    Polycrystalline M-type CaCo x Ti x Fe(12-2 x)O19 ( x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) hexagonal ferrite compositions, with substitution of Co2+ and Ti4+ ions, have been synthesized by a two-route ceramic method. Vector network analysis was used to measure various microwave and electromagnetic parameters from 8.2 GHz to 12.4 GHz. The microwave shielding effectiveness (SE) due to absorption (SEA) and reflection (SER) was investigated based on S-parameters for the near field, and intrinsic parameters, accompanied by AC conductivity and skin depth, for the far field. The shielding effectiveness was primarily governed by absorption (SEA), and substitution of Co2+ and Ti4+ ions resulted in near- and far-field SEA of 54.85 dB at 10.49 GHz and 63.43 dB at 1.15 (Ω m)-0.5, respectively, for the composition with x = 0.6. The AC conductivity exhibited a monotonic increase with frequency, whereas the skin depth decreased with frequency for all the compositions. The composition with x = 0.6 exhibited a 20-dB wide absorption bandwidth (WAB) of 3.67 GHz and 3.66 GHz for near and far field, respectively. The composition with x = 0.3 showed a 10-dB narrow absorption bandwidth (NAB) of 80 MHz for the far field.

  6. Structural and Dielectric Properties of Dy-doped( Ba, Sr, Ca) TiO3 Thick Films

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Preparation and electrocatalytic activities of Pt-TiO2 nanotubes (Ba0.57Sr0.33Ca0.10)TiO3 powders, prepared by the sol-gel method, were doped MnCO3 as acceptor and Dy2O3 as donor. This powder was mixed with an organic vehicle and BSCT thick films were fabricated by the screen-printing techniques on alumina substrate. The structural and dielectric properties of BSCT thick films were investigated with variation of Dy2O3 amount. As a result of the differential thermal analysis (DTA), exothermic peak was observed at around 670℃ due to the formation of the polycrystalline perovskite phase. All the BSCT thick films showed the XRD patterns of a typical polycrystalline perovskite structure. The average grain size of BSCT thick films decreased with increasing amount of Dy2O3. The relative dielectric constant and dielectric loss of the BSCT thick film doped Dy2O3 0. 1mol% were 4637.4 and 1.6% at 1kHz, respectively.

  7. Structural, dielectric and electrical properties of CaBa4SmTi3Nb7O30 ferroelectric ceramic

    Indian Academy of Sciences (India)

    Prasun Ganguly; A K Jha

    2011-07-01

    The polycrystalline sample of CaBa4SmTi3Nb7O30, a member of tungsten bronze family, was prepared by solid-state reaction method. X-ray diffraction analysis shows the formation of single-phase compound with an orthorhombic structure at room temperature. Scanning electron micrograph of the material shows uniform distribution of grains. Detailed studies of dielectric properties of the compound as a function of temperature at different frequencies suggest that the compound has a dielectric anomaly of ferroelectric to paraelectric type at 198°C, and exhibits non-relaxor kind of diffuse phase transition. The ferroelectric nature of the compound has been confirmed by recording polarization–electric field hysteresis loop. Piezoelectric and pyroelectric studies of the compound have been discussed in this paper. Electrical properties of the material have been analyzed using complex impedance technique. The Nyquist plots manifest the contribution of grain boundaries (at higher temperature), in addition to granular contribution (at all temperatures) to the overall impedance. The temperature dependence of dc conductivity suggests that the compound has negative temperature coefficient of resistance (NTCR) behaviour. The frequency dependence of ac conductivity is found to obey Jonscher’s universal power law. The observed properties have been compared with calcium free Ba5SmTi3Nb7O30 compound.

  8. Electrical and Pyroelectric Properties of Sol-Gel Derived (Pb, Ca)TiO3 Thin Films with Various Orientations

    Institute of Scientific and Technical Information of China (English)

    唐新桂; 丁爱丽; 王丽华

    2003-01-01

    (Pb0.76Ca0.24)TiO3(PCT)thin films with various orientations were grown on Pt/Ti/SiO2/Si substrates by using a sol-gel process and by controlling the temperature of heat-treatment.The PCT thin films with(100)and random orientation showed well-saturated hysteresis loops at an applied field of 800kV/cm,with remanent polarization and coercive electric field of 23.6 μC/cm2 and 225 k V/cm,17.8 μC/cm2 and 195 k V/cm,respectively.For highly(100)-and random-oriented PCT films,the dielectric constant and dielectric loss values of these films are 121 and 0.016,121 and 0.024 at 1 kHz,respectively.The pyroelectric coefficients p of the PCT thin films are measured by a dynamic technique.At room temperature,the p values and figures of merits of the highly(100)-and random-oriented PCT films are 185μC/m2K and 1.79 × 10-5Pa-0.5,176μC/m2K and 1.39 × 10-5Pa-0.5,respectively.

  9. Contrasting conduction mechanisms of two internal barrier layer capacitors: (Mn, Nb)-doped SrTiO3 and CaCu3Ti4O12

    Science.gov (United States)

    Tsuji, Kosuke; Chen, Wei-Ting; Guo, Hanzheng; Lee, Wen-Hsi; Guillemet-Fritsch, Sophie; Randall, Clive A.

    2017-02-01

    The d.c. conduction is investigated in the two different types of internal barrier layer capacitors, namely, (Mn, Nb)-doped SrTiO3 (STO) and CaCu3Ti4O12 (CCTO). Scanning electron microscopy (SEM) and Capacitance - Voltage (C-V) analysis are performed to estimate the effective electric field at a grain boundary, EGB. Then, the d.c. conduction mechanism is discussed based on the J (Current density)-EGB characteristics. Three different conduction mechanisms are successively observed with the increase of EGB in both systems. In (Mn, Nb)-doped STO, non-linear J-EGB characteristics is temperature dependent at the intermediate EGB and becomes relatively insensitive to the temperature at the higher EGB. The J- EGB at each regime is explained by the Schottky emission (SE) followed by Fowler-Nordheim (F-N) tunneling. Based on the F-N tunneling, the breakdown voltage is then scaled by the function of the depletion layer thickness and Schottky barrier height at the average grain boundary. The proposed function shows a clear linear relationship with the breakdown. On the other hand, F-N tunneling was not observed in CCTO in our measurement. Ohmic, Poole-Frenkel (P-F), and SE are successively observed in CCTO. The transition point from P-F and SE depends on EGB and temperature. A charge-based deep level transient spectroscopy study reveals that 3 types of trap states exist in CCTO. The trap one with Et ˜ 0.65 eV below the conduction band is found to be responsible for the P-F conduction.

  10. X-ray diffraction and Raman spectroscopic investigations on CaZrTi2O7sbnd Y2Ti2O7 system: Delineation of phase fields consisting of potential ceramic host materials

    Science.gov (United States)

    Jafar, M.; Achary, S. N.; Salke, Niliesh P.; Sahu, A. K.; Rao, Rekha; Tyagi, A. K.

    2016-07-01

    Phase evolution from CaZrTi2O7 (zirconolite) to Y2Ti2O7 (pyrochlore) have been delineated by systematic characterization of a series of sample with composition as Ca1-xZr1-xY2xTi2O7 (0.00 ≤ x ≤ 1.00) by powder XRD, Raman spectroscopy, SEM and EDS analyses. Comparative analyses of XRD and Raman spectra revealed sequential evolution of phases with increasing concentration of Y3+ in the compositions. From the XRD studies, three distinct phase fields, namely two layer (2M) and four layer (4M) zirconolite-types and cubic pyrochlore-type are observed in between zirconolite (CaZrTi2O7) and Y2Ti2O7. 4M-zirconolite phase is observed in a narrow range of composition, viz. 0.35 ≤ x ≤ 0.40 while cubic pyrochlore type phase is observed in the compositions with x ≥ 1.20. The unit cell volume of different phases shows a non-linear increasing trend with Y3+ ion concentration which has been attributed to the distribution of cations in different structure and change in their coordination number.

  11. Raman scattering and x-ray diffraction studies of polycrystalline CaCu3Ti4O12 under high-pressure

    DEFF Research Database (Denmark)

    Valim, D.; Filho, A. G. S.; Freire, P. T. C.

    2004-01-01

    We report Raman scattering and x-ray diffraction studies of polycrystalline CaCu3Ti4O12 (CCTO) under high pressures. The pressure dependence of several Raman modes was investigated. No anomalies have been observed on the phonon spectra thereby indicating that the T-h (Im (3) over bar) structure r...

  12. Effects of Fuel to Synthesis of CaTiO3 by Solution Combustion Synthesis for High-Level Nuclear Waste Ceramics.

    Science.gov (United States)

    Jung, Choong-Hwan; Kim, Yeon-Ku; Han, Young-Min; Lee, Sang-Jin

    2016-02-01

    A solution combustion process for the synthesis of perovskite (CaTiO3) powders is described. Perovskite is one of the crystalline host matrics for the disposal of high-level radioactive wastes (HLW) because it immobilizes Sr and Lns elements by forming solid solutions. Solution combustion synthesis, which is a self-sustaining oxi-reduction reaction between nitrate and organic fuel, the exothermic reaction, and the heat evolved convert the precursors into their corresponding oxide products above 1100 degrees C in air. To investigate the effects of amino acid on the combustion reaction, various types of fuels were used; a glycine, amine and carboxylic ligand mixture. Sr, La and Gd-nitrate with equivalent amounts of up to 20% of CaTiO3 were mixed with Ca and Ti nitrate and amino acid. X-ray diffraction analysis, SEM and TEM were conducted to confirm the formed phases and morphologies. While powders with an uncontrolled shape are obtained through a general oxide-route process, Ca(Sr, Lns)TiO3 powders with micro-sized soft agglomerates consisting of nano-sized primary particles can be prepared using this method.

  13. Microstructure and wear behavior of γ/Al 4C 3/TiC/CaF 2 composite coating on γ-TiAl intermetallic alloy prepared by Nd:YAG laser cladding

    Science.gov (United States)

    Liu, Xiu-Bo; Shi, Shi-Hong; Guo, Jian; Fu, Ge-Yan; Wang, Ming-Di

    2009-03-01

    As a further step in obtaining high performance elevated temperature self-lubrication anti-wear composite coatings on TiAl alloy, a novel Ni-P electroless plating method was adopted to encapsulate the as-received CaF 2 in the preparation of precursor NiCr-Cr 3C 2-CaF 2 mixed powders with an aim to decrease its mass loss and increase its compatibility with the metal matrix during a Nd:YAG laser cladding. The microstructure of the coating was examined using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) and the friction and wear behavior of the composite coatings sliding against the hardened 0.45% C steel ring was evaluated using a block-on-ring wear tester at room temperature. It was found that the coating had a unique microstructure consisting of primary dendrites TiC and block Al 4C 3 carbides reinforcement as well as fine isolated spherical CaF 2 solid lubrication particles uniformly dispersed in the NiCrAlTi ( γ) matrix. The good friction-reducing and anti-wear abilities of the laser clad composite coating was suggested to the Ni-P electroless plating and the attendant reduction of mass loss of CaF 2 and the increasing of it's wettability with the NiCrAlTi ( γ) matrix during the laser cladding process.

  14. Dielectric behaviour of CaCu3Ti4O12-epoxy composites

    Directory of Open Access Journals (Sweden)

    Leandro Alfredo Ramajo

    2008-03-01

    Full Text Available The dielectric behavior of composite materials (epoxy resin - barium titanate and epoxy - CCTO was analysed as a function of ceramic amount. Composites were prepared by mixing the components and pouring them into suitable moulds. In some compositions, the matrix was reduced by tetrahydrofuran (THF incorporation. Samples containing various amounts of ceramic filler were examined by TG/DTA and scanning electron microscopy analysis. Dielectric measurements were performed from 20 Hz to 1 MHz and 30 to 120 °C. It was demonstrated that the epoxy - CCTO composites possessed higher permittivity than classic epoxy - BaTiO3 composites. However, the low resin permittivity prevailed in the composite dielectric performance.

  15. Enhancing photoluminescence with Li-doped CaTiO{sub 3}:Eu{sup 3+} red phosphors prepared by solid state synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yibing, E-mail: ab@fafu.edu.cn [College of Mechanical and Electronic Engineering, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002 (China); Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Sun, Zhuo [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Ruan, Kaibin; Xu, Yong; Zhang, Hong [College of Mechanical and Electronic Engineering, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002 (China)

    2014-11-15

    Red phosphors of Li-doped CaTiO{sub 3}:Eu{sup 3+} that enhance photoluminescence have been synthesized by a solid-state method, and their structure and morphology were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The luminescence property was measured using photoluminescence excitation (PLE) and photoluminescence (PL) spectra, respectively. The effect of sintered temperature and Eu{sup 3+} and Li{sup +} concentration in as-prepared series phosphors was studied. Results indicate that the optimal luminescence properties of CaTiO{sub 3}:Eu{sup 3+} (CTE) phosphors are typically obtained at 1300 °C with 12 mol% of Eu{sup 3+} concentration, and the emission intensity can be greatly enhanced by the incorporation of Li{sup +} into the CTE phosphors, attributing that Li not only compensates positive charge defect by replacement of Ca{sup 2+} with Eu{sup 3+}, but also plays a role of flux, which could enhance the crystallinity of the phosphors. The intensity of the optimal Li-doped CaTiO{sub 3}:Eu{sup 3+} phosphor (CLTE) is 2.3 times of that of CTE. PL spectrum showed that CLTE phosphor was efficiently excited by near-ultraviolet light at wavelength around 398 nm and emitted intensive red light with a peak around 616 nm corresponding to the {sup 5}D{sub 0}→{sup 7}F{sub 2} transition of Eu{sup 3+}. Furthermore, this phosphor has very good thermal stability and high color purity, implying the potential to be a promising red phosphor in white light emitting diodes. - Highlights: • This paper analyses Li-doped CaTiO{sub 3}:Eu{sup 3+} phosphor. • Li-doping can compensate positive charge defect of CaTiO{sub 3}:Eu{sup 3+}. • Li-doping plays a role of flux. • Optical performance of CaTiO{sub 3}:Eu{sup 3+} can be greatly enhanced by Li-doping.

  16. Native point defects in CaCu3Ti4O12

    Science.gov (United States)

    Delugas, P.; Alippi, P.; Raineri, V.

    2010-02-01

    We report first principles computations on native point defects in CCTO. Vacancies present a general high formation energy, their concentration never exceed 1016 cm-3. Oxygen vacancies present stable positive charge states and are thus able to act as donor. Copper vacancies present instead stable negative charge states and are thus potential native acceptors for the material. As to anti-sites, the CuCa defect results to be the energetically favorite in most of the possible conditions, and may reach concentrations as high as 1019 cm-3.

  17. Improved structure stability, optical and magnetic properties of Ca and Ti co-substituted BiFeO{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vijay; Singh, Satyendra, E-mail: satyambd@gmail.com

    2016-11-15

    Graphical abstract: (a) UV–vis absorption spectra and (b) Tauc’s plots to determine the band gap of the Bi{sub 1-x}Ca{sub x}Fe{sub 1-x}Ti{sub x}O{sub 3} nanoparticles for x = 0 (S1), 0.05 (S2), 0.10 (S3), 0.15 (S4), 0.20 (S5) and 0.25 (S6), respectively (c) Variation of band gap with x for Bi{sub 1-x}Ca{sub x}Fe{sub 1-x}Ti{sub x}O{sub 3} nanoparticles. Display Omitted - Highlights: • First report on synthesis of Bi{sub 1-x}Ca{sub x}Fe{sub 1-x}Ti{sub x}O{sub 3}, nanoparticles (0 ≤ x ≤ 0.25). • Ca and Ti co-substitutions control the formation of secondary phases and improved the stability of perovskite phase. • Strong absorption of visible light with a small optical band gap (1.77–2.26 eV). • Improved M{sub r} and H{sub c} due to the release of the latent magnetization locked within the toroidal spin structure. • May be useful for data storage, spintronics and optoelectronics. - Abstract: We report the optical and magnetic properties of single-crystalline Ca and Ti co-substituted bismuth ferrite, Bi{sub 1-x}Ca{sub x}Fe{sub 1-x}Ti{sub x}O{sub 3}, nanoparticles, synthesized by a facile sol–gel methodology in the compositional range wherein 0 ≤ x ≤ 0.25. X-ray diffraction (XRD) and transmission electron microscopy (TEM) investigations show that all samples possess a rhombohedrally distorted perovskite structure with space group R3c. Ca and Ti co-substitution controls the formation of secondary phases and improved the stability of perovskite phase of BiFeO{sub 3}. The average particle size was estimated by Williamson Hall plot, confirmed by TEM, and found to be about 59, 50, 46, 41, 40 and 38 nm of Bi{sub 1-x}Ca{sub x}Fe{sub 1-x}Ti{sub x}O{sub 3} for x = 0, 0.05, 0.10, 0.15, 0.20 and 0.25, respectively. The UV–vis absorption study reveal the strong absorption of visible light with a small optical band gap (1.77–2.25 eV) for 0 ≤ x ≤ 0.25 indicates a possibility of utilizing for photocatalytic activities. The magnetic study at room

  18. Solid-state reaction mechanism and microwave dielectric properties of CaTiO{sub 3}–LaAlO{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Juan [Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Faculty of Materials Science & Engineering, Hubei University, Wuhan 430062 (China); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Hubei University, Wuhan 430062 (China); Fang, Danhua; Lu, Chao; Dou, Zhanming; Wang, Gan; Zhang, Fan [Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Faculty of Materials Science & Engineering, Hubei University, Wuhan 430062 (China); Zhang, Tianjin, E-mail: zhangtj@hubu.edu.cn [Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Faculty of Materials Science & Engineering, Hubei University, Wuhan 430062 (China); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Hubei University, Wuhan 430062 (China)

    2015-07-25

    Highlights: • CaTiO{sub 3}–LaAlO{sub 3} perovskite ceramics were prepared by four sintering reaction routes. • The solid-state reaction mechanism was investigated by XRD and TG/DSC techniques. • Sintering routes had more influence on the parameters of Q × f and τ{sub f} than on ε{sub r}. - Abstract: 0.675CaTiO{sub 3}–0.325LaAlO{sub 3} perovskite ceramics were prepared by a conventional sintering process through four reaction routes. The solid-state reaction mechanisms were investigated by X-ray diffraction and thermogravimetric/differential scanning calorimetric analysis techniques. The results show that interactions occurred between mixtures of CaCO{sub 3} and TiO{sub 2} as well as La{sub 2}O{sub 3} and Al{sub 2}O{sub 3}, and they can influence the sintering behavior of the mixtures. Prior to the formation of solid solutions, the perovskite phases CaTiO{sub 3} and LaAlO{sub 3} were formed regardless of the combination of oxide powders used as reagents. From the powder mixtures which were calcined at 1200 °C, a Ca-rich Ca{sub 9}Al{sub 6}O{sub 18} phase was present at 1400 °C if free La{sub 2}O{sub 3} and Al{sub 2}O{sub 3} used in the reaction mixtures. Ca-rich phases were also formed at higher temperature (1450 °C) if LaAlO{sub 3} was present. The densities of the ceramics obtained by the four routes were different at specific sintering temperatures, and the highest density was obtained for the reaction route two. Results indicated that the preparation pathways had more influence on Q × f and temperature coefficient of the resonant frequency (τ{sub f}) than on the dielectric constants (ε{sub r}), and Q × f decreased and τ{sub f} increased rapidly when the secondary phase presented. Route four is considered as an optimal pathway for the preparation of 0.675CaTiO{sub 3}–0.325LaAlO{sub 3} ceramics.

  19. Elastic properties of amorphous T 0.75Y0.75B14 (T  =  Sc, Ti, V, Y, Zr, Nb) and the effect of O incorporation on bonding, density and elasticity (T'  =  Ti, Zr).

    Science.gov (United States)

    Hunold, Oliver; Keuter, Philipp; Bliem, Pascal; Music, Denis; Wittmers, Friederike; Ravensburg, Anna L; Primetzhofer, Daniel; Schneider, Jochen M

    2017-03-01

    We have systematically studied the effect of transition metal valence electron concentration (VEC) of amorphous T 0.75Y0.75B14 (a-T 0.75Y0.75B14, T  =  Sc, Ti, V, Y, Zr, Nb) on the elastic properties, bonding, density and electronic structure using ab initio molecular dynamics. As the transition metal VEC is increased in both periods, the bulk modulus increases linearly with molar- and mass density. This trend can be understood by a concomitant decrease in cohesive energy. T'  =  Ti and Zr were selected to validate the predicted data experimentally. A-Ti0.74Y0.80B14 and a-Zr0.75Y0.75B14 thin films were synthesized by high power pulsed magnetron sputtering. Chemical composition analysis revealed the presence of up to 5 at.% impurities, with O being the largest fraction. The measured Young's modulus values for a-Ti0.74Y0.80B14 (301  ±  8 GPa) and a-Zr0.75Y0.75B14 (306  ±  9 GPa) are more than 20% smaller than the predicted ones. The influence of O incorporation on the elastic properties for these selected systems was theoretically studied, exemplarily in a-Ti0.75Y0.75B12.75O1.25. Based on ab initio data, we suggest that a-Ti0.75Y0.75B14 exhibits a very dense B network, which is partly severed in a-Ti0.75Y0.75B12.75O1.25. Upon O incorporation, the average coordination number of B and the molar density decrease by 9% and 8%, respectively. Based on these data the more than 20% reduced Young's modulus obtained experimentally for films containing impurities compared to the calculated Young's modulus for a-Ti0.75Y0.75B14 (without incorporated oxygen) can be rationalized. The presence of oxygen impurities disrupts the strong B network causing a concomitant decrease in molar density and Young's modulus. Very good agreement between the measured and calculated Young's modulus values is obtained if the presence of impurities is considered in the calculations. The implications of these findings are that prediction efforts regarding the

  20. Electroless deposition of brushite (CaHPO{sub 4} . 2 H{sub 2}O) crystals on Ti-6Al-4V at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Tas, A.C. [Clemson Univ., SC (United States). Dept. of Materials Science and Engineering

    2006-05-15

    An electroless, room temperature solution growth method of depositing 50 to 150 {mu}m thick, well-crystallized brushite (CaHPO{sub 4} . 2 H{sub 2}O, DCPD, dicalcium phosphate dihydrate) layers on the surface of an implantable medical device, such as a titanium alloy (Ti-6Al-4V) substrate, was developed. High ionic strength (189 to 609 mM) solutions with a Ca/P molar ratio of 2.50 and a pH value between 4.70 and 6.10 were prepared by dissolving appropriate quantities of CaCl{sub 2} . 2 H{sub 2}O, NaH{sub 2}PO{sub 4}, NaHCO{sub 3}, and NaCl in deionized water. Surface-etched Ti-6Al-4V substrates were simply soaked in the solutions from 24 to 72 hours at room temperature. Elongated CaHPO{sub 4} . 2 H{sub 2}O crystals were in-situ-grown on the entire surfaces of the etched Ti-6Al-4V substrates. (orig.)

  1. Effect of Rare Earth Oxides on the Microstructure and Microwave Dielectric Properties of CaO-MgO-Nb2O5-TiO2 System Ceramics

    Institute of Scientific and Technical Information of China (English)

    WANG Hao; CHEN Wen; LIU Tao

    2005-01-01

    La2 O3 and SrO-doped CaO-MgO-Nb2 O5-TiO2 system ceramics were prepared by solid-state ceramic technique. The microstructure and microwave dielectric properties of CaO-MgO-Nb2 O5 -TiO2-La2 O3 ceramics can be adjusted by varying the amount of La3+ or Sr2+ ions respectively. The replacement of Ca2+ by La3+ at A-site of the ceramics increases the quality factor Q value ( at 7.6 GHz) as well as the temperature coefficient of resonant frequency τfand decreases the dielectric constant εr and the substitution of Sr2+ at A-site in this ceramics system exhibits opposite characteristics. The microwave properties of La3+ , Sr2+ -doped CaO-MgO-Nb2 O5 - TiO2 system ceramics depend on the degree of octahedral distortion inside materials .

  2. Ferroelectric, piezoelectric, and dielectric properties of BiScO3-PbTiO3-Pb(Cd1/3Nb2/3)O3 ternary high temperature piezoelectric ceramics

    Science.gov (United States)

    Zhao, Tian-Long; Chen, Jianguo; Wang, Chun-Ming; Yu, Yang; Dong, Shuxiang

    2013-07-01

    (0.95-x)BiScO3-xPbTiO3-0.05Pb(Cd1/3Nb2/3)O3 (BS-xPT-PCN) high temperature piezoelectric ceramics near the morphotropic phase boundary (MPB) have been synthesized by traditional solid-state reaction methods. The microstructural morphology, phase structure, and electrical properties of BS-xPT-PCN ceramics were investigated in detail. X-ray diffraction analysis indicated BS-xPT-PCN ceramics have a pure perovskite structure. The coexistence of rhombohedral and tetragonal phases at MPB composition enhanced the polarizability by the coupling between two dynamically equivalent energy states, resulting in the improved piezoelectric and ferroelectric properties at MPB vicinity. The BS-xPT-PCN (x = 0.60) ceramics possess the optimal piezoelectric and ferroelectric properties with d33 = 505pC/N, kp = 55.9%, kt = 36.5%, strain = 0.23% (under the electric field 37.5 kV/cm), and Pr = 39.7 μC/cm2. High temperature dielectric behaviors showed diffuse phase transition in BS-xPT-PCN ceramics. The Curie temperature Tc was found to increase from 371 °C to 414 °C with x increasing from 0.58 to 0.62. All these results together with the good thermal stabilities make the BS-xPT-PCN ceramics promising candidates for high temperature piezoelectric applications.

  3. Charged FeC{sub n} clusters: A comparison with TMC{sub n}{sup +}/TMC{sub n}{sup -} (TM = Sc, Ti, V, Co and Zn, n = 1-8) systems

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, Pilar, E-mail: predondo@qf.uva.es [Computacional Chemistry Group, Departamento de Quimica Fisica y Quimica Inorganica, Facultad de Ciencias, Universidad de Valladolid, 47005 Valladolid (Spain); Largo, Laura; Barrientos, Carmen [Computacional Chemistry Group, Departamento de Quimica Fisica y Quimica Inorganica, Facultad de Ciencias, Universidad de Valladolid, 47005 Valladolid (Spain)

    2009-10-16

    The electronic and geometrical structures of the ground and excited states for the linear, fan and cyclic isomers of FeC{sub n}{sup +}andFeC{sub n}{sup -} (n = 1-8) compounds are calculated using the B3LYP method. A comparison of these results with the previously obtained for TMC{sub n}{sup +}/TMC{sub n}{sup -} (TM = Sc, Ti, V, Co and Zn) systems, is carried out. Quartet and sextet states are found the most stables for FeC{sub n}{sup +} clusters. Linear FeC{sub n}{sup -} clusters prefer doublet and quartet ground states, whereas for cyclic and fan isomers the most stables are quartet and sextet ones. n-odd linear, fan, and cyclic FeC{sub n}{sup +} isomers are more stable than adjacent n-even ones. For FeC{sub n}{sup -} clusters the opposite trend is found for linear and fan structures, whereas for cyclic isomers the relative stability decreases along the series. In general linear isomers are the most stable conformations for FeC{sub n}{sup +}/FeC{sub n}{sup -} clusters. Systematic trends of different properties are analyzed for TMC{sub n}{sup +}/TMC{sub n}{sup -} clusters.

  4. Piezoelectric and Dielectric Properties of Fe2O3-Doped 0.57Pb(Sc1/2Nb1/2)O3 0.43PbTiO3 Ceramic Materials

    Science.gov (United States)

    Kim, Jin-Soo; Kim, So-Jung; Kim, Ho-Gi; Lee, Duck-Chool; Uchino, Kenji

    1999-03-01

    High-power piezoelectric materials are presently being extensively developed for applications such as ultrasonic motors and piezoelectric transformers. In this study, the piezoelectric and dielectric properties of Fe2O3-doped 0.57Pb(Sc1/2Nb1/2)O3 0.43PbTiO3 (hereafter 0.57PSN 0.43PT), which is the morphotropic phase boundary composition of the PSN PT system, were investigated. The maximum dielectric constant (ɛ33/ɛ0=2551) and the minimum dielectric loss (tanδ=0.51%) at room temperature were obtained at Fe2O3 additions of 0.1 wt% and 0.3 wt%, respectively. The temperature dependence of the dielectric constant and the dielectric loss was measured between room temperature and 350°C. With the addition of Fe2O3, the piezoelectric constant d33 and electromechanical coupling factor kp were slightly decreased, but the mechanical quality factor Qm was significantly increased. The highest mechanical quality factor (Qm=297) was obtained at 0.3 wt% Fe2O3, which is 4.4 times higher than that of nondoped 0.57PSN 0.43PT ceramics. The P E and S E loops of the samples at room temperature and at 1.0 Hz were measured at the same time using an automated polarization measuring system.

  5. Evaluation of the effect of the stoichiometric ratio of Ca/Cu on the electrical and microstructural properties of the CaCu3Ti4O12 polycrystalline system

    Science.gov (United States)

    Ramírez, M. A.; Bueno, P. R.; Tararam, R.; Cavalheiro, A. A.; Longo, E.; Varela, J. A.

    2009-09-01

    The structural, microstructural, non-ohmic and dielectric properties of perovskite-type CaCu3Ti4O12 (CCTO) with Ca/Cu stoichiometries of 1/3, 1/1 and 3/1 are discussed. The 1/3 Ca/Cu ratio system presents very high dielectric permittivity (~9000 at 10 kHz) and a low non-ohmic property (α = 9), whereas the 1/1 Ca/Cu ratio system shows the opposite effect, i.e. the dielectric permittivity decreases (2740 at 10 kHz) and the non-ohmic property increases (α = 42), indicating that these properties are not directly correlated. The results of this work reinforce the idea that the greatest contribution to the very high permittivity is caused by the presence of planar defects inside the CCTO grains, generating internal nanometric domains associated with stacking faults, according to the nanoscale barrier layer capacitance model proposed very recently in the literature [1]. The non-ohmic property is related to the presence and distribution of phases such as CaTiO3 (CTO) and CuO, segregated or precipitated at the grain boundary, which generate large numbers of electrically active interfaces.

  6. Consequences of embedding Ti4+ 3d0 centers in Pr0.50Ca0.50MnO3 : Phase competition in Pr0.50Ca0.50Mn1-xTixO3

    Science.gov (United States)

    García-Muñoz, J. L.; Frontera, C.; Beran, P.; Bellido, N.; Hernández-Velasco, J.; Ritter, C.

    2010-01-01

    We have studied the structural and magnetic phase coexistence/competition derived from the partial random substitution of 3d0 nonmagnetic Ti4+ ions for Mn in Pr0.50Ca0.50MnO3 , and their evolution with the doping level in Pr0.50Ca0.50Mn1-xTixO3 ( x=0 , 0.01, 0.03, and 0.05) manganites. Combining high-resolution synchrotron, neutron powder-diffraction, and muon techniques we describe with great detail the coexistence of two different structural phases below ≈240K (charge-order transition temperature, TCO ) with different cell distortion, antiferromagnetic order, and strain characteristics. The evolution of all these features with Ti substitution level is thoroughly described. Ti4+ (3d0) ions do not favor the stabilization of ferromagnetic/metallic (FM/M) islands/regions in the antiferromagnetic/insulating (AFM/I) orbital-ordered matrix. The absence of short- and long-range ferromagnetism in zero field has been confirmed by different techniques. The proportion of microdomains exhibiting pseudo-(CE)-type magnetic order (CE: charge exchange) increases with the Ti content at expenses of the CE-type regions. Differences in the stability of competing phases against magnetic field have been found by neutron-diffraction measurements under application of external fields. The phase coexistence exhibits strong anisotropic strain effects that have been thoroughly analyzed as a function of the Ti content x . We have found very remarkable changes in the strain characteristics of the AFM segregated phases on going from 1% to 5% Ti. Large anisotropic strains develop mainly in the minority phase of the material. The magnitude of strains is discussed in comparison with anisotropic strain values recently determined in the case of substitutions (such as Co) that favor FM/M domains.

  7. Neutron total scattering and reverse Monte Carlo study of cation ordering in Ca(x)Sr(1-x)TiO(3).

    Science.gov (United States)

    Hui, Qun; Dove, Martin T; Tucker, Matthew G; Redfern, Simon A T; Keen, David A

    2007-08-22

    We use neutron total scattering measurements with reverse Monte Carlo analysis methods incorporating an atom-swapping algorithm to identify the short-range Ca/Sr cation ordering within the Ca(x)Sr(1-x)TiO(3) solid solution (compositions x = 0.2,0.5,0.8). Our results show that nearest-neighbour pairs have a strong tendency for unlike Ca/Sr first-neighbour coordination in the x = 0.2 and 0.5 cases. In the x = 0.5 case the Ca/Sr ordering results in a structure with space group P 2(1)nm. In contrast, there is much less short-range cation ordering in the x = 0.8 case.

  8. Phase developments and dielectric responses of barium substituted four-layer CaBi4Ti4O15 Aurivillius

    Indian Academy of Sciences (India)

    Huiling Du; Xiang Shi; Huilu Li

    2011-10-01

    In this paper, mixed Ca–Ba oxide Ca1−BaBi4Ti4O15 (CBBT) ceramics, fabricated by the improved traditional ceramics process were investigated by doping concentrations of Ba ion up to = 0.9 (in steps of 0.1). At room temperature, an orthorhombic crystal system was confirmed using XRD, and their parameter was obtained using the Rietveld method. Dielectric properties and phase transitions were studied and are explained in terms of lattice response of these ceramics. A shift in ferroelectric–paraelectric phase transition (C) to lower temperatures and a corresponding decrease in permittivity peak with increasing concentration of Ba2+ are also observed. The ferroelectric–paraelectric phase transition of CBBT compounds is of normal type in nature, differing from the relaxor characteristic of BBT. The decrease of orthorhombicity in the lattice structure by the larger Ba2+ ion incorporation, indicating an approach of and , results in lower Curie temperature. Appearance of anomalous loss peaks of Ba-rich compounds at 530°C reveals a phase transition development trend from ferroelectric orthorhombic structure to the paraelectric orthorhombic structure. Relationship of polarization with lattice response is discussed.

  9. Preparation and Characterization of Nanostructured CaCu2.90Zn0.10Ti4O12 Ceramic

    Directory of Open Access Journals (Sweden)

    Laxman Singh

    2011-12-01

    Full Text Available Nanostructure CaCu2.90Zn0.10Ti4O12 (CCZTO electronic ceramic was synthesized by semi‐wet route. The objective of this route is to enable the calcination and sintering processes to go for completion in shorter time and at lower temperature.The samples were characterized by XRD, TEM, SEM and EDX analyses. The crystallite size of the CCZTO ceramic, obtained by XRD using Debye Scherrer formula, range from 38‐74nm which is in good agreement with the particle size observed by TEM analysis. It was observed clearly that the grain size significantly increased with an increase in sintering duration. Dielectric measurements were carried out by LCR meter in the temperature range, 300‐ 500K, at few selected frequencies. It was also observed that the dielectric constant and dielectric loss of CCZTO are temperature independent in higher frequency whereas temperature dependent in low frequency region. The ceramics exhibit high dielectric constant of 1.35 x 104 at 1 kHz.

  10. Research Update: Polyimide/CaCu3Ti4O12 nanofiber functional hybrid films with improved dielectric properties

    Science.gov (United States)

    Yang, Yang; Wang, Ziyu; Ding, Yi; Lu, Zhihong; Sun, Haoliang; Li, Ya; Wei, Jianhong; Xiong, Rui; Shi, Jing; Liu, Zhengyou; Lei, Qingquan

    2013-11-01

    This work reports the excellent dielectric properties of polyimide (PI) embedded with CaCu3Ti4O12 (CCTO) nanofibers. The dielectric behaviors were investigated over a frequency of 100 Hz-1 MHz. It is shown that embedding CCTO nanofibers with high aspect ratio (67) is an effective means to enhance the dielectric permittivity and reduce the percolation threshold. The dielectric permittivity of PI/CCTO nanofiber composites is 85 with 1.5 vol.% loading of filler, also the dielectric loss is only 0.015 at 100 Hz. Monte Carlo simulation was used to investigate the percolation threshold of CCTO nanofibers reinforced polyimide matrix by using excluded volume theory and soft, hard-core models. The results are in good agreement with the percolation theory and the hard-core model can well explain the percolation phenomena in PI/CCTO nanofiber composites. The dielectric properties of the composites will meet the practical requirements for the application in high dielectric constant capacitors and high energy density materials.

  11. Role of Relaxation on the Giant Permittivity and Electrical Properties of CaCu3Ti4O12 Ceramics

    Science.gov (United States)

    Zhao, Xuetong; Ren, Lulu; Liao, Ruijin; Li, Jianying; Yang, Lijun; Wang, Feipeng

    2016-06-01

    CaCu3Ti4O12 (CCTO) ceramics were synthesized under various sintering conditions to investigate the role of relaxation on permittivity and electrical properties. Two relaxation processes that respectively related to grain and to domain boundary at a temperature as low as 223 K were fitted according to the Cole-Cole theory. The results indicate that both relaxations largely account for the giant permittivity of CCTO ceramics. Moreover, the relaxation behaviors of grain and of the grain boundary can be processed via impedance plots that vary from 113 K to 473 K. It is shown that longer sintering duration leads to lower resistance of grain and of grain boundary: e.g., from 3200 Ω to 810 Ω and 1.76 MΩ to 0.48 MΩ, respectively. The activation energy related to grain-boundary relaxation drops from 1.14 eV to 0.80 eV, while the value of grain stays unchanged at about 0.11 eV. The Schottky barrier of the CCTO sample decreases from 0.65 eV to 0.57 eV. It is also proposed that the nonlinearity of current-voltage property for CCTO ceramics may be strongly related to the relaxation processes of grain boundaries.

  12. Research Update: Polyimide/CaCu3Ti4O12 nanofiber functional hybrid films with improved dielectric properties

    Directory of Open Access Journals (Sweden)

    Yang Yang

    2013-11-01

    Full Text Available This work reports the excellent dielectric properties of polyimide (PI embedded with CaCu3Ti4O12 (CCTO nanofibers. The dielectric behaviors were investigated over a frequency of 100 Hz–1 MHz. It is shown that embedding CCTO nanofibers with high aspect ratio (67 is an effective means to enhance the dielectric permittivity and reduce the percolation threshold. The dielectric permittivity of PI/CCTO nanofiber composites is 85 with 1.5 vol.% loading of filler, also the dielectric loss is only 0.015 at 100 Hz. Monte Carlo simulation was used to investigate the percolation threshold of CCTO nanofibers reinforced polyimide matrix by using excluded volume theory and soft, hard-core models. The results are in good agreement with the percolation theory and the hard-core model can well explain the percolation phenomena in PI/CCTO nanofiber composites. The dielectric properties of the composites will meet the practical requirements for the application in high dielectric constant capacitors and high energy density materials.

  13. Influence of Fabrication Parameters on the Phase Formation and Dielectric Properties of CaCu3Ti4012 Ceramics

    Institute of Scientific and Technical Information of China (English)

    Qian Zheng; Huiqing Fant

    2012-01-01

    The giant dielectric permittivity materials CaCu3Ti4012 (CCTO) were synthesized by conventional solid-state reaction techniques. X-ray diffraction and Raman scattering for the powder indicate that the powder calcined at 950 ℃ for 12 h has been completely transformed into the purer CCTO phase. Furthermore, the morphology and size of the grains of the ceramics sintered at 1090 ℃ in the dwell time range from 0 to 26 h were observed by scanning electron microscopy (SEM). Dielectric properties of the polycrystalline CCTO ceramics were characterized in a broad frequency range (100 Hz-1 MHz) and at a temperature ranged from 300 to 500 K. The longer sintering time may lead to more defect structures and the enhanced conductivity, also leads to substantial improvements in permittivity. Grain size and density differences were not large enough to account for the enhancement in dielectric permittivity. Based on the observations, it is believed that the primary factor affecting dielectric behavior is the development of internal defects. The CCTO ceramics sintered at 1090 ℃ for 15 h exhibit lower dielectric loss (-0.05) near room temperature, and the dielectric relaxation behavior above 1 kHz was observed to follow the Arrhenius law. The activation energy (Ea) of 0.65 eV indicates that the doubly ionized oxygen vacancies in the grain boundaries are responsible for the dielectric relaxation of the CCTO ceramics.

  14. Effect of microwave-assisted sintering on dielectric properties of CaCu3Ti4O12 ceramic

    Science.gov (United States)

    Rani, Suman; Ahlawat, Neetu; Punia, R.; Kundu, R. S.; Ahlawat, N.

    2016-05-01

    In this present work, CaCu3Ti4O12 (CCTO) was synthesized by conventional solid-state reaction technique. The synthesis process was carried out in two phases; by conventional process (calcination and sintering at 1080°C for 10 hours) and phase II involves the micro assisted pre sintering of conventionally calcined CCTO for very short soaking time of 30 min at 1080°C in a microwave furnace followed by sintering at 1080°C for 10 hours in conventional furnace. X-ray diffraction (XRD) patterns confirmed the formation of single phase ceramic. Dielectric properties were studied over the frequency range from 50Hz -5MHz at temperatures (273K-343K). It was observed that pre- microwave sintering enhance the dielectric constant values from 10900 to 11893 and respectively reduces the dielectric loss values from 0.49 to 0.34 at room temperature(1 KHz). CCTO ceramics which are found desirable for many technological applications. The effect is more pronounced at low frequencies of applied electric field.

  15. Synthesis and microwave dielectric properties of Ca substituted SrLa4Ti4.93Zr0.07O17 ceramics

    Indian Academy of Sciences (India)

    Abdul Manan; Ibrahim Qazi

    2014-05-01

    Microwave dielectric ceramics in Sr1-CaLa4Ti4.93Zr0.07O17 (0 ≤ ≤ 0.5) composition series were processed via a solid-state sintering rout. X-ray diffraction revealed single phase ceramics. Ca substitutions for Sr tuned f towards zero with increased uo values. In the present study, r∼ 55, uo ∼ 11960 GHz and ∼ 5.2 ppm/°C were achieved for the composition with = 0.3.

  16. Raman tensor and domain structure study of single-crystal-like epitaxial films of CaCu3Ti4O12 grown by pulsed laser deposition

    Science.gov (United States)

    Ahlawat, Anju; Mishra, Dileep K.; Sathe, V. G.; Kumar, Ravi; Sharma, T. K.

    2013-01-01

    The local domain structure of a strain free, 150 nm thick, epitaxially grown single crystalline thin film of CaCu3Ti4O12 is probed by polarized Raman spectroscopy. The polarization dependence of the Raman intensities of the observed bands as a function of varying angle between the domain axes and the polarization vector of the scattered laser photon is measured. Theoretical formulations involving the Raman tensor are presented, which enable determination of the domain structure from the observed polarized Raman spectra, and a single-crystal-like domain structure is found. The Raman tensor elements and domain orientation direction were determined by fitting the observed Raman intensities with theoretical calculations and by carrying out Raman mapping of the film. Our data show an absence of twin domain structure and twin domain boundaries in the single-crystal-like epitaxial thin films of CaCu3Ti4O12.

  17. Exploration of Ca0.5Ti2(PO4)3@carbon Nanocomposite as the High-Rate Negative Electrode for Na-Ion Batteries.

    Science.gov (United States)

    Wei, Zhixuan; Meng, Xing; Yao, Ye; Liu, Qiang; Wang, Chunzhong; Wei, Yingjin; Du, Fei; Chen, Gang

    2016-12-28

    Exploring suitable electrode materials with high specific capacity and high-rate capability is a challenging goal for the development of Na-ion batteries. Here, we report a NASICON-structured compound, Ca0.5Ti2(PO4)3, with respect to its synthesis and electrochemical properties. The electrode is found to enable fast Na(+) ion diffusion owing to the rich crystallographic vacancies, affording a reversible capacity of 264 mA h g(-1) between 3.0 and 0.01 V. In particular, the hybrid Ca0.5Ti2(PO4)3@carbon exhibits remarkable rate performance with a discharge capacity of nearly 45 mA h g(-1) at a current density of 20 A g(-1), which is attributed to the pseudocapacitive effect.

  18. S-C Mylonites

    NARCIS (Netherlands)

    Lister, G.S.; Snoke, A.W.

    1984-01-01

    Two types of foliations are commonly developed in mylonites and mylonitic rocks: (a) S-surfaces related to the accumulation of finite strain and (b) C-surfaces related to displacement discontinuities or zones of relatively high shear strain. There are two types of S-C mylonites. Type I S-C mylonites

  19. Dielectric properties of Zr doped CaCu{sub 3}Ti{sub 4}O{sub 12} synthesized by sol-gel route

    Energy Technology Data Exchange (ETDEWEB)

    Jesurani, S. [Department of Physics, Jeyaraj Annapackium College for Women, Periyakulam 625 601, Tamil Nadu (India); Center for Material Science and Nano Devices, Department of Physics, SRM University, Kattankulathur 603 203, Tamil Nadu (India); Kanagesan, S., E-mail: kanagu1980@gmail.com [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hashim, M. [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Physics Department, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Ismail, I. [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2013-02-25

    Highlights: Black-Right-Pointing-Pointer Zr doped CaCu{sub 3}Ti{sub 4}O{sub 12} samples have been synthesized using sol-gel process. Black-Right-Pointing-Pointer The particle size of the powder ranges from 47 to 85 nm. Black-Right-Pointing-Pointer Less sintering at 1040 Degree-Sign C results in high density and high dielectric constant. - Abstract: Zr substituted CaCu{sub 3}Ti{sub 4-x}Zr{sub x}O{sub 12} (CCTZO) with x = 0.00, 0.02, 0.10, 0.20 and 0.50 mol% were prepared by sol-gel route from the metal nitrate solutions, Titanium isoproxide, and zirconium oxy chloride. XRD analysis confirmed the formation of a single phase material in the samples calcinated at 800 Degree-Sign C for 3 h. The crystal structure did not change on doping with zirconium and it remained cubic in all the four studied compositions. The permittivity and dielectric loss of 0.1 mol% Zr doped CaCu{sub 3}Ti{sub 4}O{sub 12} were improved for K Almost-Equal-To 6020 and tan {delta} Almost-Equal-To 0.52 at 1 kHz after the sample had been sintered at 1040 Degree-Sign C for 4 h. AFM studies showed that the particle size of the CCTZO powder ranged from 47 to 85 nm. FE-SEM micrographs of the CaCu{sub 3}Ti{sub 4-x}Zr{sub x}O{sub 12} samples showed that the grain size was in the range of 250 nm to 5 {mu}m for these samples. EDX studies showed the presence of calcium, copper, titanium, oxygen and zirconium. Remarkably, the dielectric constant increased and dielectric loss had lower values compared to the undoped CCTO.

  20. Observation of coherent phonons in Ca-doped SrTiO{sub 3}: Doping-induced ferroelectric phase transition and ultraviolet-illumination effect

    Energy Technology Data Exchange (ETDEWEB)

    Koyama, Y; Okamura, H; Kohmoto, T [Graduate School of Science, Kobe University, Kobe 657-8501 (Japan); Moriyasu, T [Graduate School of Science and Technology, Kobe University, Kobe 657-8501 (Japan); Yamada, Y [Institute for Chemical Research, Kyoto University, Kyoto 611-0011 (Japan); Tanaka, K, E-mail: kohmoto@kobe-u.ac.j [Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan)

    2009-02-01

    Photo-induced effect in Ca-doped SrTiO{sub 3} was investigated by observing coherent phonons. Coherent phonons of soft modes were studied by using ultrafast polarization spectroscopy. Under an ultraviolet (UV) illumination, a shift of the ferroelectric phase transition point at 28 K toward the lower temperature side was observed, and a decrease of phonon frequencies after the UV illumination was found.

  1. Abnormal dielectric behaviors in Mn-doped CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics and their response mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yuan-Hua, E-mail: linyh@tsinghua.edu.cn [State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Deng, Wei [State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Xu, Wei [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Liu, Yong [State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Chen, Dongliang; Zhang, Xiaoli [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Nan, Ce-Wen [State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer Mn-doping affects the electric behaviors remarkably in CCTO ceramics. Black-Right-Pointing-Pointer The activation energy of grain and grain boundary disappears with increasing the Mn doping concentration. Black-Right-Pointing-Pointer The XANES spectra reveal that valence states of Ti, Mn and Cu in the grain and grain boundary changes greatly. - Abstract: Mn-doped CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) polycrystalline ceramics have been prepared by the conventional solid state sintering. Our results indicate that 10% Mn doping can decrease the dielectric permittivity in CaCu{sub 3}Ti{sub 4}O{sub 12} by about 2 orders of magnitude (from 10{sup 4} to 10{sup 2}). The grain and grain boundary activation energies show an obvious increase from 0.054 eV to 0.256 eV, and decrease from 0.724 eV to 0.258 eV with increasing the Mn doping concentration, respectively, which may be caused by the variation of Cu and Ti valence states in the CCTO samples evidenced by the X-ray absorption spectra. The similar grain and grain boundary activation energies result in invalidation of the internal boundary layer capacitance effect for the 10% Mn-doped CCTO sample, and thus result in the dramatic decrease of dielectric permittivity.

  2. Fission and quasifission of composite systems with Z =108 -120 : Transition from heavy-ion reactions involving S and Ca to Ti and Ni ions

    Science.gov (United States)

    Kozulin, E. M.; Knyazheva, G. N.; Novikov, K. V.; Itkis, I. M.; Itkis, M. G.; Dmitriev, S. N.; Oganessian, Yu. Ts.; Bogachev, A. A.; Kozulina, N. I.; Harca, I.; Trzaska, W. H.; Ghosh, T. K.

    2016-11-01

    Background: Suppression of compound nucleus formation in the reactions with heavy ions by a quasifission process in dependence on the reaction entrance channel. Purpose: Investigation of fission and quasifission processes in the reactions 36S,48Ca,48Ti , and 64Ni+238U at energies around the Coulomb barrier. Methods: Mass-energy distributions of fissionlike fragments formed in the reaction 48Ti+238U at energies of 247, 258, and 271 MeV have been measured using the double-arm time-of-flight spectrometer CORSET at the U400 cyclotron of the Flerov Laboratory of Nuclear Reactions and compared with mass-energy distributions for the reactions 36S,48Ca,64Ni+238U . Results: The most probable fragment masses as well as total kinetic energies and their dispersions in dependence on the interaction energies have been investigated for asymmetric and symmetric fragments for the studied reactions. The fusion probabilities have been deduced from the analysis of mass-energy distributions. Conclusion: The estimated fusion probability for the reactions S, Ca, Ti, and Ni ions with actinide nuclei shows that it depends exponentially on the mean fissility parameter of the system. For the reactions with actinide nuclei leading to the formation of superheavy elements the fusion probabilities are of several orders of magnitude higher than in the case of cold fusion reactions.

  3. Hybrid improper ferroelectricity in Ruddlesden-Popper Ca{sub 3}(Ti,Mn){sub 2}O{sub 7} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X. Q., E-mail: xqliu@zju.edu.cn, E-mail: xmchen59@zju.edu.cn; Wu, J. W.; Shi, X. X.; Zhao, H. J.; Zhou, H. Y.; Chen, X. M., E-mail: xqliu@zju.edu.cn, E-mail: xmchen59@zju.edu.cn [Laboratory of Dielectric Materials, School of Materials Science and Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China); Qiu, R. H.; Zhang, W. Q. [Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444 (China)

    2015-05-18

    The hybrid improper ferroelectricity (HIF) has been proposed as a promising way to create multiferroic materials with strong magnetoelectric coupling by the first-principle calculation, and the experimental evidences of HIF in Ruddlesden-Poper Ca{sub 3}(Ti{sub 1−x}Mn{sub x}){sub 2}O{sub 7} (x = 0, 0.05, 0.1, and 0.15) ceramics have been shown in the present work. The room temperature ferroelectric hysteresis loops are observed in these ceramics, and a polar orthorhombic structure with two oxygen tilting modes has been confirmed by the X-ray powder diffraction. A first-order phase transition around 1100 K in Ca{sub 3}Ti{sub 2}O{sub 7} was evidenced, and the temperatures of phase transitions decrease linearly with increasing of the contents of Mn{sup 4+} ions. Based on the result of first-principle calculations, the polarization should be reversed by switching through the mediated Amam phase in Ca{sub 3}Ti{sub 2}O{sub 7} ceramics.

  4. Improvement in the microwave dielectric properties of SrCa4Nb4TiO17 ceramics by Ba substitution

    Indian Academy of Sciences (India)

    Abdul Manan; Yaseen Iqbal

    2014-10-01

    Microwave dielectric ceramics in the Sr1–BaCa4Nb4TiO17 (0 ≤ ≤ 0.75) composition series were fabricated via a solid-state mixed oxide route. All the compositions formed single phase in Sr1–BaCa4Nb4TiO17 (0 ≤ ≤ 0.75) solid solutions within the detection limit of in-house X-ray diffraction (XRD). The sintered microstructure of these ceramics comprised densely packed elongated and plate-like grains. The dielectric properties varied linearly with . Relative permittivity (r) increased from 47.2 to 54.5, unloaded quality factor multiplying the resonant frequency (u o) decreased from 11,984 to 9345 GHz and temperature coefficient of resonant frequency (f) increased from –78.6 to 20 ppm/°C with an increase in x from 0 to 0.75. In the present study, r ≈ 51.6, u o ≈ 10,160 GHz (5.37 GHz) and f ≈ –13.5 ppm/°C were achieved for Sr0.5Ba0.5Ca4Nb4TiO17 ( = 0.5) ceramics.

  5. Study on the influence of rutile nano-TiO2 on performance of CaSO4 whisker/PP-R resin composite%金红石型纳米TiO2对CaSO4晶须/PP-R树脂复合材料性能的影响

    Institute of Scientific and Technical Information of China (English)

    邹敏; 王琪琳

    2009-01-01

    以金红石型纳米TiO2为添加剂改善了CaSO4晶须/PP-R树脂复合材料的各项性能,并研究了金红石型纳米TiO2对PP-R树脂的力学性能、耐热性能和紫外老化性能的影响.研究结果表明:由于纳米TiO2和CaSO4晶须的协同作用,添加纳米TiO2后可进一步提高CaSO4晶须/PP-R树脂复合材料的力学性能和耐热性能;金红石纳米TiO2的加入可以大幅度提高PP-R树脂的耐紫外老化性能,添加5%纳米TiO2后的CaSO4晶须/PP-R树脂复合材料经紫外辐射72 d后,其拉伸强度仅下降了0.36MPa,冲击强度仅下降了0.36kJ·m-2,熔融温度仅下降了5.4℃;而未添加纳米TiO2的CaSO4晶须/PP-R树脂复合材料的拉伸强度下降了1.96MPa,冲击强度下降了1.47kJ·m-2,熔融温度下降了18.6℃.%The performances of CaSO4 whisker/PP-R resin composites, such as the mechanics performance, heat performance and ultraviolet aging performance, had been improved by adding rutile nanometer titanium dioxide. The results showed that adding the rutile nano-TiO2 can improve the performances of CaSO4 whisker/PP-R resin composite farther than adding CaSO4 whisker only because of the cooperation of two stuffs. The results also showed the ultraviolet aging performance of CaSO4 whisker/PP-R resin composite adding 5% can be improved greatly. The rutile nano-TiO2/CaSO4 whisker/PP-R resin composite radiated by UV after 72days, it's tensile strength was 0. 36MPa, Intensity of impact was 0. 36KJ·m-2 and it' s softening point was 5. 4℃. But the CaSO4 whisker/PP-R resin composite radiated by UV after 72days, it's tensile strength was 1.96MPa, Intensity of impact was 1.46KJ·m-2 and it's softening point cut was 18. 6℃.

  6. Ferroelectric, piezoelectric, and dielectric properties of BiScO{sub 3}-PbTiO{sub 3}-Pb(Cd{sub 1/3}Nb{sub 2/3})O{sub 3} ternary high temperature piezoelectric ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Tianlong [Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China); School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Chen Jianguo; Dong Shuxiang [Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Wang Chunming [School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Yu Yang [Faculty of Physics and Electronic Technology, Hubei University, Wuhan 430062 (China)

    2013-07-14

    (0.95-x)BiScO{sub 3}-xPbTiO{sub 3}-0.05Pb(Cd{sub 1/3}Nb{sub 2/3})O{sub 3} (BS-xPT-PCN) high temperature piezoelectric ceramics near the morphotropic phase boundary (MPB) have been synthesized by traditional solid-state reaction methods. The microstructural morphology, phase structure, and electrical properties of BS-xPT-PCN ceramics were investigated in detail. X-ray diffraction analysis indicated BS-xPT-PCN ceramics have a pure perovskite structure. The coexistence of rhombohedral and tetragonal phases at MPB composition enhanced the polarizability by the coupling between two dynamically equivalent energy states, resulting in the improved piezoelectric and ferroelectric properties at MPB vicinity. The BS-xPT-PCN (x = 0.60) ceramics possess the optimal piezoelectric and ferroelectric properties with d{sub 33} = 505pC/N, k{sub p} = 55.9%, k{sub t} = 36.5%, strain = 0.23% (under the electric field 37.5 kV/cm), and P{sub r} = 39.7 {mu}C/cm{sup 2}. High temperature dielectric behaviors showed diffuse phase transition in BS-xPT-PCN ceramics. The Curie temperature T{sub c} was found to increase from 371 Degree-Sign C to 414 Degree-Sign C with x increasing from 0.58 to 0.62. All these results together with the good thermal stabilities make the BS-xPT-PCN ceramics promising candidates for high temperature piezoelectric applications.

  7. Energy dependence of thermoluminescent response of CaSO{sub 4}:Dy, LiF:Mg and micro LiF:Mg,Ti in clinical beams of electrons by using different simulator objects; Dependencia energetica da resposta TL de dosimetros de CaSO{sub 4}:Dy, LiF:Mg e microLiF:Mg,Ti em feixes clinicos de eletrons utilizando diferentes objetos simuladores

    Energy Technology Data Exchange (ETDEWEB)

    Bravim, Amanda; Campos, Leticia Lucente, E-mail: abravin@ipen.b, E-mail: rsakuraba@einstein.b, E-mail: lcrodri@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Sakuraba, Roberto K.; Cruz, Jose Carlos da, E-mail: rsakuraba@einstein.b, E-mail: josecarlosc@einstein.b [Hospital Israelita Albert Einstein (HIAE), Sao Paulo, SP (Brazil)

    2011-10-26

    Yet not so widely applied in radiotherapy, the calcium sulfate doped with dysprosium (CaSO{sub 4}:Dy) is used in radioprotection and studies has been demonstrated its great potential for the dosimetry in radiotherapy. This work evaluates the energy dependence of the thermoluminescent answer of the CaSO{sub 4}:D, LiF:Mg,Ti (TLD-100) and micro LiF:Mg,Ti in clinical beams of electrons by using water simulators, PMMA and solid water

  8. Improved tribo-mechanical behavior of CaP-containing TiO2 layers produced on titanium by shot blasting and micro-arc oxidation.

    Science.gov (United States)

    Szesz, Eduardo M; de Souza, Gelson B; de Lima, Gabriel G; da Silva, Bruno A; Kuromoto, Neide K; Lepienski, Carlos M

    2014-10-01

    The combination of shot blasting (SB) and micro-arc oxidation (or anodic oxidation--AO) in titanium surfaces was shown to provide enhanced conditions for cell differentiation and osseointegration than those provided by SB or AO alone. This study associated both methods aiming to attain titania layers on Ti with adequate tribo-mechanical features for bone implants. SB was performed using alumina particles, and titania layers were grown by AO using a CaP-based electrolyte. Mechanical properties and scratch resistance were characterized at nanoscale by instrumented indentation and nanoscratch, and correlated with morphological and microstructural changes (XRD, SEM, EDS, AFM, and profilometry). Analytical methods were employed to correct roughness and substrate effects on the indentation results. CaP-containing TiO2 layers were produced on AO and SB + AO. The latter presented small pore size and inhomogeneous layer thickness and Ca/P ratios, caused by the non-uniform surface straining by SB that affects the oxide growth kinetics in the electrochemical process. Elastic modulus of SB + AO layer (37 GPa) were lower than the AO one (45 GPa); both of them were smaller than bulk Ti (130 GPa) and close to bone values. The hardness profiles of AO and SB + AO were similar to the substrate ones. Because of the improved load bearing capacity and unique layer features, the critical load to remove the SB + AO titania coating in scratch tests was three times as much or higher than in AO. Results indicate improved mechanical biocompatibility and tribological strength of anodic titania layers grown on sand blasted Ti surfaces.

  9. Influence of CaZrO3 on dielectric properties and microstructures of BaTiO3-based X8R ceramics

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The influences of CaZrO3 on the dielectric properties and microstructures of BaTiO3 (BT)-based ceramics have been investigated. The experiment results showed that the dielectric constant at room temperature increased with the addition of CaZrO3 in the range of 0―3.0 mol%, which could be explained by the growth of BT grains. XRD analysis revealed that the tetragonality declined as CaZrO3 concentration in-creased. XRD patterns of BT ceramics with different amounts of CaZrO3 doping were analyzed by a recently developed procedure-materials analysis using diffrac-tion (MAUD), which was based on the Rietveld method combined with Fourier analysis. The results depicted that the high temperature peak of tempera-ture-capacitance characteristics (TCC) was largely dependent on the micro-strain of samples. Furthermore, more CaZrO3 doping resulted in lower porosity and higher density. It was revealed that proper usage of CaZrO3 could improve the di-electric properties significantly, which was benefit to develop X8R multi-layer ce-ramic capacitors.

  10. Influence of CaZrO3 on dielectric properties and microstructures of BaTiO3-based X8R ceramics

    Institute of Scientific and Technical Information of China (English)

    TANG Bin; ZHANG ShuRen; YUAN Ying; ZHOU XiaoHua; LIANG YiShuai

    2008-01-01

    The influences of CaZrO3 on the dielectric properties and microstructures of BaTiO3 (BT)-based ceramics have been investigated. The experiment results showed that the dielectric constant at room temperature increased with the addition of CaZrO3 in the range of 0-3.0 mol%, which could be explained by the growth of BT grains. XRD analysis revealed that the tetragonality declined as CaZrO3 concentration in- creased. XRD patterns of BT ceramics with different amounts of CaZrO3 doping were analyzed by a recently developed procedure-materials analysis using diffrac- tion (MAUD), which was based on the Rietveld method combined with Fourier analysis. The results depicted that the high temperature peak of tempera- ture-capacitance characteristics (TCC) was largely dependent on the micro-strain of samples. Furthermore, more CaZrO3 doping resulted in lower porosity and higher density. It was revealed that proper usage of CaZrO3 could improve the di- electric properties significantly, which was benefit to develop X8R multi-layer ce- ramic capacitors.

  11. CaO-Al2O3-TiO2熔渣表面张力计算模型%CALCULATING MODELS ON THE SURFACE TENSION OF CaO-Al2O3-TiO2 MOLTEN SLAG

    Institute of Scientific and Technical Information of China (English)

    吴铖川; 成国光

    2014-01-01

    基于熔渣结构离子与分子共存理论和Butler方程,建立了CaO-Al2O3-TiO2熔渣表面张力计算模型.本模型利用纯组元的表面张力和摩尔体积以及熔渣中各组元表面相和体相中作用浓度(活度)可以计算出CaO-Al2 O3-TiO2熔渣表面张力随熔渣成分、温度的变化规律.将计算得到的表面张力值与文献实测值进行对比,计算结果与文献实测值吻合较好.并进一步绘制了CaO-Al2O3-TiO2熔渣等表面张力线,考察了炉渣成分对表面张力的影响,以期为含TiO2渣系控制提供理论参考.

  12. Dielectric and varistor properties of rare-earth-doped ZnO and CaCu3Ti4O12 composite ceramics

    Science.gov (United States)

    Lu, Huafei; Lin, Yuanhua; Yuan, Jiancong; Nan, Cewen; Chen, Kexin

    2013-02-01

    To investigate the multi-functional ceramics with both high permittivity and large nonlinear coefficient, we have prepared rare-earth Tb-and-Co doped ZnO and TiO2-rich CaCu3Ti4O12 (TCCTO) powders by chemical co-precipitation and sol-gel methods respectively, and then obtained the TCCTO/ZnO composite ceramics, sintered at 1100°C for 3 h in air. Analyzing the composite ceramics of the microstructure and phase composition indicated that the composite ceramics were composed of the main phases of ZnO and CaCu3Ti4O12 (CCTO). Our results revealed that the TCCTO/ZnO composite ceramics showed both high dielectric and good nonlinear electrical behaviors. The composite ceramic of TCCTO: ZnO = 0.3 exhibited a high dielectric constant of 210(1 kHz) with a nonlinear coefficient of 11. The dielectric behavior of TCCTO/ZnO composite could be explained by the mixture rule. With the high dielectric permittivity and tunable varistor behaviors, the composite ceramics has a potential application for the higher voltage transportation devices.

  13. Preparation and Characterization of Red Luminescent Ca0.8Zn0.2TiO3: Pr3+, Na+ Nanophosphor

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Nanophosphor with the nominal composition of Ca0.8Zn0.2TiO3∶Pr3+, Na+ (CZTOPN) was synthesized at relatively low temperature by the sol-gel method. Metal ions were dispersed by citric acid in ethylene glycol solvent and then react with Ti(OC4H9)4 to form sol and gel. The decomposition process of the precursor, and crystallization and particle size of CZTOPN were examined by thermal analysis (TG-DSC), powder X-ray diffraction (XRD), and scan election microscopy (SEM). Results of TG-DSC and XRD reveal that the composition of Ca0.8Zn0.2TiO3∶Pr3+, Na+ changes with the sintering temperature. SEM data indicate that the diameter of particles is under 50 nm even if the sintering temperature increases to 1000 ℃. In contrast to a solid state reaction, the excitation spectra of samples synthesized by the sol-gel method shift blue about 10 nm and the emission intensity at 617 nm increases significantly.

  14. Elastic properties of amorphous T 0.75Y0.75B14 (T  =  Sc, Ti, V, Y, Zr, Nb) and the effect of O incorporation on bonding, density and elasticity (T‧  =  Ti, Zr)

    Science.gov (United States)

    Hunold, Oliver; Keuter, Philipp; Bliem, Pascal; Music, Denis; Wittmers, Friederike; Ravensburg, Anna L.; Primetzhofer, Daniel; Schneider, Jochen M.

    2017-03-01

    We have systematically studied the effect of transition metal valence electron concentration (VEC) of amorphous T 0.75Y0.75B14 (a-T 0.75Y0.75B14, T  =  Sc, Ti, V, Y, Zr, Nb) on the elastic properties, bonding, density and electronic structure using ab initio molecular dynamics. As the transition metal VEC is increased in both periods, the bulk modulus increases linearly with molar- and mass density. This trend can be understood by a concomitant decrease in cohesive energy. T‧  =  Ti and Zr were selected to validate the predicted data experimentally. A-Ti0.74Y0.80B14 and a-Zr0.75Y0.75B14 thin films were synthesized by high power pulsed magnetron sputtering. Chemical composition analysis revealed the presence of up to 5 at.% impurities, with O being the largest fraction. The measured Young’s modulus values for a-Ti0.74Y0.80B14 (301  ±  8 GPa) and a-Zr0.75Y0.75B14 (306  ±  9 GPa) are more than 20% smaller than the predicted ones. The influence of O incorporation on the elastic properties for these selected systems was theoretically studied, exemplarily in a-Ti0.75Y0.75B12.75O1.25. Based on ab initio data, we suggest that a-Ti0.75Y0.75B14 exhibits a very dense B network, which is partly severed in a-Ti0.75Y0.75B12.75O1.25. Upon O incorporation, the average coordination number of B and the molar density decrease by 9% and 8%, respectively. Based on these data the more than 20% reduced Young’s modulus obtained experimentally for films containing impurities compared to the calculated Young’s modulus for a-Ti0.75Y0.75B14 (without incorporated oxygen) can be rationalized. The presence of oxygen impurities disrupts the strong B network causing a concomitant decrease in molar density and Young’s modulus. Very good agreement between the measured and calculated Young’s modulus values is obtained if the presence of impurities is considered in the calculations. The implications of these findings are that prediction efforts

  15. Influence of interface point defect on the dielectric properties of Y doped CaCu3Ti4O12 ceramics

    Science.gov (United States)

    Deng, Jianming; Sun, Xiaojun; Liu, Saisai; Liu, Laijun; Yan, Tianxiang; Fang, Liang; Elouadi, Brahim

    2016-04-01

    CaCu3Ti4-xYxO12 (0≤x≤0.12) ceramics were fabricated with conventional solid-state reaction method. Phase structure and microstructure of prepared ceramics were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The impedance and modulus tests both suggested the existence of two different relaxation behavior, which were attributed to bulk and grain boundary response. In addition, the conductivity and dielectric permittivity showed a step-like behavior under 405K. Meanwhile, frequency independence of dc conduction became dominant when above 405K. In CCTO ceramic, rare earth element Y3+ ions as an acceptor were used to substitute Ti sites, decreasing the concentration of oxygen vacancy around grain-electrode and grain boundary. The reason to the reduction of dielectric behavior in low frequencies range was associated with the Y doping in CCTO ceramic.

  16. High-pressure investigation of CaTiO3 up to 60 GPa using x-ray diffraction and Raman spectroscopy

    Science.gov (United States)

    Guennou, Mael; Bouvier, Pierre; Krikler, Benjamin; Kreisel, Jens; Haumont, Raphaël; Garbarino, Gaston

    2010-10-01

    In this work, we investigate calcium titanate [CaTiO3(CTO)] using x-ray diffraction and Raman spectroscopy up to 60 GPa and 55 GPa, respectively. Both experiments show that the orthorhombic Pnma structure remains stable up to the highest pressures measured, in contradiction to ab initio predictions. A fit of the compression data with a second-order Birch-Murnaghan equation of state yields a bulk modulus K0 of 181.0(6) GPa. The orthorhombic distortion is found to increase slightly with pressure, in agreement with previous experiments at lower pressures and the general rules for the evolution of perovskites under pressure. High-pressure polarized Raman spectra also enable us to clarify the Raman mode assignment of CTO and identify the modes corresponding to rigid rotation of the octahedra, A -cation shifts, and Ti-O bond stretching. The Raman signature is then discussed in terms of compression mechanisms.

  17. Hydrothermal growth of TiO{sub 2}-CaP nano-films on a Ti–Nb-based alloy in concentrated calcium phosphate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongwei, E-mail: lihw74@foxmail.com [Chang’an University, School of Materials Science and Engineering (China); Fu, Tao, E-mail: taofu@mail.xjtu.edu.cn [Xi’an Jiaotong University, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology (China); Li, Wen [Chang’an University, School of Materials Science and Engineering (China); Alajmi, Zafer; Sun, Jiamao [Xi’an Jiaotong University, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology (China)

    2016-01-15

    The Ti–Nb-based TLM alloy (Ti–25Nb–3Zr–2Sn–3Mo) was subjected to hydrothermal treatment in the concentrated Ca{sub 3}(PO{sub 4}){sub 2}, CaHPO{sub 4}, and Ca(H{sub 2}PO{sub 4}){sub 2} solutions for the purpose of calcification. The treated samples are covered by films consisting of Ca-rich nano-crystallites (100–500 nm) and small nano-grains. XPS and XRD analyses reveal the formation of hydroxyapatite, TiO{sub 2}, and Nb{sub 2}O{sub 5} at the sample surface. The sample hydrothermally treated in CaHPO{sub 4} solution exhibits bioactivity by inducing the formation of apatite layer after soaking test in the simulated body fluid for 15 days. The work would provide a good bioactive surface modification method for Ti–Nb alloy implants with complex shapes and even pores.

  18. Sorption properties and reversibility of Ti(IV) and Nb(V)-fluoride doped-Ca(BH{sub 4}){sub 2}-MgH{sub 2} system

    Energy Technology Data Exchange (ETDEWEB)

    Bonatto Minella, Christian, E-mail: christian.minella@kit.edu [Institute for Metallic Materials, IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden (Germany); Technische Universität Dresden, D-01062 Dresden (Germany); Garroni, Sebastiano [Dipartimento di Chimica e Farmacia, Universitá di Sassari and INSTM, Via Vienna 2, I-07100 Sassari (Italy); Pistidda, Claudio [Institute of Materials Research, Materials Technology, Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung GmbH, Max Planck Str. 1, D-21502 Geesthacht (Germany); Baró, Maria Dolors [Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Spain); Gutfleisch, Oliver [Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt (Germany); Klassen, Thomas; Dornheim, Martin [Institute of Materials Research, Materials Technology, Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung GmbH, Max Planck Str. 1, D-21502 Geesthacht (Germany)

    2015-02-15

    Highlights: • Faster desorption reaction for doped materials vs. the pure composite system. • Kinetic improvement concerning re-hydrogenation reaction showed by the addition of NbF{sub 5}. • Full characterization of the de-hydrogenation reaction pathway by means of both SR-PXD and {sup 11}B{"1H} MAS-NMR. • Study of the evolution of the chemical state of the additives upon both milling and sorption reactions. - Abstract: In the last decade, alkaline and alkaline earth metal tetrahydroborates have been the focuses of the research due to their high gravimetric and volumetric hydrogen densities. Among them, Ca(BH{sub 4}){sub 2} and the Ca(BH{sub 4}){sub 2} + MgH{sub 2} reactive hydride composites (RHC), were calculated to have the ideal thermodynamic properties which fall within the optimal range for mobile applications. In this study, the addition of NbF{sub 5} or TiF{sub 4} to the Ca(BH{sub 4}){sub 2} + MgH{sub 2} reactive hydride composite system was attempted aiming to obtain a full reversible system with the simultaneous suppression of CaB{sub 12}H{sub 12}. Structural characterization of the specimens was performed by means of in-situ Synchrotron Radiation Powder X-ray diffraction (SR-PXD) and {sup 11}B{"1H} Solid State Magic Angle Spinning-Nuclear Magnetic Resonance (MAS-NMR). The evolution of the chemical state of the Nb- and Ti-based additives was monitored by X-ray Absorption Near Edge Structure (XANES). The addition of NbF{sub 5} or TiF{sub 4} to the Ca(BH{sub 4}){sub 2} + MgH{sub 2} system have not suppressed completely the formation of CaB{sub 12}H{sub 12} and only a slight improvement concerning the reversible reaction was displayed just in the case of Nb-doped composite material.

  19. Piezoelectric and upconversion emission properties of Er3+-doped 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramic

    Institute of Scientific and Technical Information of China (English)

    戴君丽; 杜鹏; 徐佳丹; 徐超祥; 罗来慧

    2015-01-01

    In this investigation, the ferroelectric, piezoelectric properties, and upconversion (UC) emissions of Er3+-doped 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT) were investigated. The results showed that the ferroelectric and piezoelectric per-formances of BZT-BCT ceramics decreased with the increment of Er doping content. Under the excitation of 980 nm light, all sam-ples exhibited strong green UC emissions. A maximum green UC emission was observed in BZT-BCT:0.015Er. The variation of the UC emission with Er doping content did not coincide with that of electrical properties of the ceramics. The relation between the UC emission and piezoelectric properties was discussed.

  20. Fusion and quasifission dynamics in the reactions 48Ca+249Bk and 50Ti+249Bk using a time-dependent Hartree-Fock approach

    Science.gov (United States)

    Umar, A. S.; Oberacker, V. E.; Simenel, C.

    2016-08-01

    Background: Synthesis of superheavy elements (SHEs) with fusion-evaporation reactions is strongly hindered by the quasifission (QF) mechanism which prevents the formation of an equilibrated compound nucleus and which depends on the structure of the reactants. New SHEs have been recently produced with doubly-magic 48Ca beams. However, SHE synthesis experiments with single-magic 50Ti beams have so far been unsuccessful. Purpose: In connection with experimental searches for Z =117 ,119 superheavy elements, we perform a theoretical study of fusion and quasifission mechanisms in 48Ca,50Ti+249Bk reactions in order to investigate possible differences in reaction mechanisms induced by these two projectiles. Methods: The collision dynamics and the outcome of the reactions are studied using unrestricted time-dependent Hartree-Fock (TDHF) calculations as well as the density-constrained TDHF method to extract the nucleus-nucleus potentials and the excitation energy in each fragment. Results: Nucleus-nucleus potentials, nuclear contact times, masses and charges of the fragments, as well as their kinetic and excitation energies strongly depend on the orientation of the prolate 249Bk nucleus. Long contact times associated with fusion are observed in collisions of both projectiles with the side of the 249Bk nucleus, but not on collisions with its tip. The energy and impact parameter dependencies of the fragment properties, as well as their mass-angle and mass-total kinetic energy correlations are investigated. Conclusions: Entrance channel reaction dynamics are similar with both 48Ca and 50Ti projectiles. Both are expected to lead to the formation of a compound nucleus by fusion if they have enough energy to get in contact with the side of the 249Bk target.

  1. Effect of TiO2 and CaF2 on the Microstructure and High-Temperature Viscosity of Parent Glass from Blast Furnace Slag%TiO2和CaF2对高炉渣基础玻璃微观结构和高温粘度的影响

    Institute of Scientific and Technical Information of China (English)

    谢春帅; 贵永亮; 王亚文; 宋春燕; 胡宾生

    2016-01-01

    以高炉渣为主要原料,添加适当的SiO2、Al2O3、MgO、ZnO、K2CO3、Na2CO3、TiO2、CaF2等化学试剂作为辅助材料,采用熔融法制备了高炉渣基础玻璃。通过拉曼光谱和熔体物性测定仪分析了TiO2和CaF2对高炉渣基础玻璃微观结构和高温粘度的影响。结果显示随着TiO2含量的增加,Si4+逐步被Ti4+取代,使非桥氧数目增加,拉曼峰向低波数移动。CaF2中的F-取代硅氧四面体中的O2-,硅氧四面体断裂,使拉曼峰降低。TiO2和CaF2均能降低基础玻璃高温粘度,有利于基础玻璃的熔制,同时增加了基础玻璃对热的不稳定性,有利于基础玻璃的形核析晶形成微晶玻璃。%Parent glass was prepared successfully by the method of melting, using blast furnace slag as main source of raw materials, and SiO2, Al2O3, MgO, ZnO, K2CO3, Na2CO3, TiO2 and CaF2 as auxiliary materials. The microstructure and high-temperature viscosity of parent glass were investigated by the Raman spectra and high-temperature melt properties tester. The results showed that with the increase of TiO2 content in parent glass more Si4+was replaced by Ti4+, which led to an increased amount of non-bridging oxygen and the movement of the Raman peaks to lower wave number. F-tended to occupy the place of O2-in parent glass with the increasing of CaF2 content. As a result, silicon oxygen tetrahedron fractured and the intensity of the Raman spectra lowered. The presence of TiO2 and CaF2 was beneifcial for the homogeneity of parent glass due to the decreasing of the viscosity of liquid glass, but it also increased the thermal instability of parent glass, which was helpful for nucleation and crystallization of glass ceramics.

  2. Mn掺杂改性高温无铅压电陶瓷CaBi4Ti4O15的研究

    Institute of Scientific and Technical Information of China (English)

    初瑞清; 徐志军

    2007-01-01

    用固相合成法制备Mn掺杂改性的CaBi4Ti4O15(CBT)高温无铅压电陶瓷。分析表明,利用固相合成法制备Mn掺杂CBT的温度为850℃,制备Mn掺杂改性CBT陶瓷的烧结温度随锰含量的增加降低,压电常数影响不大。

  3. Elastic anomaly around a ferromagnetic transition in Y{sub 1-x}Ca{sub x}TiO{sub 3} (x=0-0.2)

    Energy Technology Data Exchange (ETDEWEB)

    Morita, Shinya [Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan); Higaki, Haruhiro [Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan); Ishii, Isao [Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan); Takemura, Masaki [Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan); Iga, Fumitoshi [Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan); Takabatake, Toshiro [Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan); Tsubota, Masami [JAERI/Spring-8, Hyogo 679-5198 (Japan); Suzuki, Takashi [Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan)]. E-mail: tsuzuki@hiroshima-u.ac.jp

    2006-08-15

    We measured temperature dependence of elastic modulus for the high-quality single crystals of Y{sub 1-x}Ca{sub x}TiO{sub 3} (x=0,0.1 and 0.2) using an ultrasonic technique. A step like elastic anomaly due to the volume magnetostriction induced by a ferromagnetic transition was observed in longitudinal C{sub 11} and C{sub 33} for x=0 and 0.1, although no anomaly was observed for x=0.2. With increasing x, the magnitude of anomaly decreases, reflecting that the amplitude of the antiferromagnetic orbital order parameter, where the orbital ordering is the origin of the ferromagnetism of YTiO{sub 3}, is reduced with increasing Ca concentration.

  4. Enhanced electrical and magnetic properties in La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films deposited on CaTiO{sub 3}-buffered silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Adamo, C. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Méchin, L.; Guillet, B.; Wu, S.; Routoure, J.-M. [Groupe de Recherche en Informatique, Image, Automatique et Instrumentation de Caen, (GREYC-UMR 6072), CNRS-ENSICAEN—Université de Caen Basse-Normandie, 6 Boulevard Maréchal Juin, 14050 Caen Cedex (France); Heeg, T. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853-1501 (United States); Katz, M.; Pan, X. Q. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Mercone, S. [Laboratoire de Sciences des Procédés et des Matériaux, UPR3407, CNRS, Institut Galilee, Universite Paris-Nord, Villetaneuse (France); Schubert, J.; Zander, W. [Peter Grünberg Institute (PGI9-IT), JARA-Fundamentals of Future Information Technology, Research Centre Jülich, Jülich D-52425 (Germany); Misra, R. [Department of Physics and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Schiffer, P. [Department of Physics and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); and others

    2015-06-01

    We investigate the suitability of an epitaxial CaTiO{sub 3} buffer layer deposited onto (100) Si by reactive molecular-beam epitaxy (MBE) for the epitaxial integration of the colossal magnetoresistive material La{sub 0.7}Sr{sub 0.3}MnO{sub 3} with silicon. The magnetic and electrical properties of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films deposited by MBE on CaTiO{sub 3}-buffered silicon (CaTiO{sub 3}/Si) are compared with those deposited on SrTiO{sub 3}-buffered silicon (SrTiO{sub 3}/Si). In addition to possessing a higher Curie temperature and a higher metal-to-insulator transition temperature, the electrical resistivity and 1/f noise level at 300 K are reduced by a factor of two in the heterostructure with the CaTiO{sub 3} buffer layer. These results are relevant to device applications of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films on silicon substrates.

  5. Enhanced electrical and magnetic properties in La0.7Sr0.3MnO3 thin films deposited on CaTiO3-buffered silicon substrates

    Directory of Open Access Journals (Sweden)

    C. Adamo

    2015-06-01

    Full Text Available We investigate the suitability of an epitaxial CaTiO3 buffer layer deposited onto (100 Si by reactive molecular-beam epitaxy (MBE for the epitaxial integration of the colossal magnetoresistive material La0.7Sr0.3MnO3 with silicon. The magnetic and electrical properties of La0.7Sr0.3MnO3 films deposited by MBE on CaTiO3-buffered silicon (CaTiO3/Si are compared with those deposited on SrTiO3-buffered silicon (SrTiO3/Si. In addition to possessing a higher Curie temperature and a higher metal-to-insulator transition temperature, the electrical resistivity and 1/f noise level at 300 K are reduced by a factor of two in the heterostructure with the CaTiO3 buffer layer. These results are relevant to device applications of La0.7Sr0.3MnO3 thin films on silicon substrates.

  6. Effect of (Ba_(0.6)Sr_(0.4))TiO_3(BST) Doping on Dielectric Properties of CaCu_3Ti_4O_(12)(CCTO)%Effect of (Ba_(0.6)Sr_(0.4))TiO_3(BST) Doping on Dielectric Properties of CaCu_3Ti_4O_(12)(CCTO)

    Institute of Scientific and Technical Information of China (English)

    I. Norezan; A.K. Yahya; M.K. Talari

    2012-01-01

    The effect of (Ba(0.6)Sr(0.4))TiO3(BST) addition on dielectric properties of CaCu3Ti4O(12) (CCTO) ceramic was investigated. Ceramic samples with the chemical formula (1-x)CaCu3Ti4O(12) + x(Ba(0.6),Sr(0.4))TiO3 (x=0, 0.05, 0.1, and 0.2) were synthesized from high purity oxide powders by the conventional solid-state synthesis method. X-ray diffraction (XRD) analysis showed the existence of BST as a secondary phase alongside CCTO. Scanning electron microscopy (SEM) investigation showed a slight decrease in grain size of doped CCTO samples. Density measurements showed that porosity content increased with increasing BST addition indicating low densification due to high melting point secondary phase addition. Dielectric constant of undoped CCTO (x=0) showed lack of stability with frequency which dropped drastically between 104 and 105Hz and accompanied by high dielectric loss. Addition of BST into CCTO caused the dielectric constant to slightly decrease but improved stability with frequency compared to the undoped sample. The decrease in dielectric constant of doped CCTO samples was suggested to be partly due to the decrease in average grain size and increase in porosity with BST addition. Nevertheless, a high value of dielectric constant was still maintained around ~104 range for all doped samples. The dielectric loss (tanδ) of all BST-doped samples was lower than that of pure CCTO sample at the frequency range of 103 to 105 Hz probably due to the increase of grains boundary resistivity. The activation energy of grains boundary (E(gb)) showed higher values as compared to the activation energy of grains (Eg ) for all samples and conforms to the internal barrier layer capacitor (IBLC) model.

  7. Giant dielectric behavior and electrical properties of Ca{sub 1-3x/2}Lu{sub x}Cu{sub 3}Ti{sub 4}O{sub 12} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Boonlakhorn, Jakkree [Khon Kaen University, Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen (Thailand); Kidkhunthod, Pinit [Synchrotron Light Research Institute (Public Organization), Nakhon Ratchasima (Thailand); Putasaeng, Bundit; Yamwong, Teerapon [Thailand Science Park, National Metal and Materials Technology Center (MTEC), Pathumthani (Thailand); Thongbai, Prasit [Khon Kaen University, Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen (Thailand); Khon Kaen University, Department of Physics, Faculty of Science, Khon Kaen (Thailand); Maensiri, Santi [Suranaree University of Technology, Institute of Science, School of Physics, Nakhon Ratchasima (Thailand)

    2015-07-15

    Giant dielectric behavior and electrical properties of Ca{sub 1-3x/2}Lu{sub x}Cu{sub 3}Ti{sub 4}O{sub 12} ceramics were studied by focusing on the influences of Lu{sup 3+} doping on their microstructure and electrical properties. The mean grain size of CaCu{sub 3}Ti{sub 4}O{sub 12} was greatly reduced as the dopant content was increased to 15 at.% (x = 0.15), which was ascribed to the effect of solute drag. X-ray absorption near-edge structure confirmed the presence of Ti{sup 3+} ions in Ca{sub 1-3x/2}Lu{sub x} Cu{sub 3}Ti{sub 4}O{sub 12} ceramics. The ratio of Ti{sup 3+}/Ti{sup 4+} in CaCu{sub 3}Ti{sub 4}O{sub 12} was reduced by Lu{sup 3+} doping. Dielectric permittivity (ε') decreased with increasing Lu{sup 3+} content, which was ascribed to reduce grain boundary capacitance caused by the presence of Lu{sup 3+}. Activation energies for conduction in the grain interiors and at the grain boundaries were slightly changed with Lu{sup 3+} content. Interestingly, improved dielectric properties with ε' ∝3.56 x 10{sup 4} and tan δ ∝0.059 at 1 kHz in the Ca{sub 0.925}Lu{sub 0.05}Cu{sub 3}Ti{sub 4}O{sub 12} ceramic were achieved. (orig.)

  8. {sup 48}Ti(n,xnpa{gamma}) reaction cross sections using spallation neutrons for E{sub n} = 1 to 20 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Dashdorj, D; Mitchell, G E; Garrett, P E; Agvaanluvsan, U; Becker, J A; Bernstein, L A; Cooper, J R; Hoffman, R D; Younes, W; Devlin, N; Fotiades, N; Nelson, R O

    2005-01-06

    {gamma}-ray excitation functions have been measured for the interaction of fast neutrons with {sup 48}Ti (neutron energy from 1 MeV to 250 MeV). The Los Alamos National Laboratory spallation neutron source, at the LANSCE/WNR facility, provided a ''white'' neutron beam which is produced by bombarding a natural W target with a pulsed proton beam. The prompt-reaction {gamma} rays were measured with the large-scale Compton-suppressed Ge spectrometer, GEANIE. Neutron energies were determined by the time-of-flight technique. Excitation functions were converted to partial {gamma}-ray cross sections, taking into account the dead-time correction, the target thickness, the detector efficiency, and neutron flux (monitored with an in-line fission chamber). The data analysis is presented here for neutron energies between 1 to 20 MeV. Partial {gamma}-ray cross sections for transitions in {sup 47,48}Ti, {sup 48}Sc, and {sup 45}Ca have been determined. These results are compared to Hauser-Feshbach predictions calculated using the STAPRE code, which includes compound nuclear and pre-equilibrium emission. The partial cross sections for {gamma} rays, whose discrete {gamma}-ray cascade path leads to the ground state in {sup 48}Ti, {sup 47}Ti, {sup 48}Sc, and {sup 45}Ca have been summed to obtain estimates of the lower limits for reaction cross sections. Partial cross sections for unobserved {gamma}-rays are predicted from the STAPRE code. These lower limits are combined with Hauser-Feshbach calculations to deduce {sup 48}Ti(n,n'){sup 48}Ti, {sup 48}Ti(n,2n){sup 47}Ti, {sup 48}Ti(n,p){sup 48}Sc, and {sup 48}Ti(n,{alpha}){sup 45}Ca reaction channel cross sections.

  9. SC tuning fork

    CERN Multimedia

    The tuning fork used to modulate the radiofrequency system of the synchro cyclotron (SC) from 1957 to 1973. This piece is an unused spare part. The SC was the 1st accelerator built at CERN. It operated from August 1957 until it was closed down at the end of 1990. In the SC the magnetic field did not change with time, and the particles were accelerated in successive pulses by a radiofrequency voltage of some 20kV which varied in frequency as they spiraled outwards towards the extraction radius. The frequency varied from 30MHz to about 17Mz in each pulse. The tuning fork vibrated at 55MHz in vacuum in an enclosure which formed a variable capacitor in the tuning circuit of the RF system, allowing the RF to vary over the appropriate range to accelerate protons from the centre of the macine up to 600Mev at extraction radius. In operation the tips of the tuning fork blade had an amplitude of movement of over 1 cm. The SC accelerator underwent extensive improvements from 1973 to 1975, including the installation of a...

  10. Preparação e caracterização microestrutural de cerâmicas ferroelétricas de Ba0,77Ca0,23TiO3 Preparation and microstructural characterization of Ba0.77Ca0.23TiO3 ferroelectric ceramics

    Directory of Open Access Journals (Sweden)

    T. Mazon

    2004-06-01

    Full Text Available Cerâmicas de titanato de bário e cálcio com composição Ba0.77Ca0.23TiO3 (BCT23 foram produzidas usando o método de síntese por reação de estado sólido. Um estudo sistemático de temperatura e tempo de calcinação foi realizado com o objetivo de se determinar as condições experimentais ótimas para a obtenção da fase única BCT23. Observou-se a presença das fases BaTiO3 e CaTiO3 para os pós calcinados em temperaturas inferiores a 1200 ºC e tempo de até 12 horas. Um aumento na temperatura para 1250 ºC leva a formação da fase BCT23. Os pós calcinados a 1250 ºC foram prensados uniaxialmente em diferentes condições e sinterizados a 1450 ºC / 4h. Verificou-se que o método utilizado para a preparação dos compactos influenciou na microestrutura e densidade relativa das cerâmicas. Cerâmicas mais densas foram obtidas a partir da prensagem com pressão uniaxial equivalente a 1x10(7 N/m² dos pós de BCT23 peneirados.Barium calcium titanate ceramics with composition Ba0,77Ca0,23TiO3 (BCT23 were prepared by solid state reaction. A systematic study of temperature and time of calcination was performed aiming to determine the experimental conditions to obtain only BCT23 phase. It was only observed the BaTiO3 and CaTiO3 phases at calcination temperature up to 1200 ºC and time up to 12 h. However, it was possible to obtain the BCT23 phase by increasing the temperature to 1250 ºC for 12 h. The powders calcined at 1250 ºC for 12 h were uniaxially pressed at different conditions and sintered at 1450 ºC / 4h. The method utilized to prepare the compacts influenced on the microstructure and relative density of the ceramics. Denser ceramics were obtained by pressing a BCT23 powder with 1x10(7 N/m².

  11. Enhanced photoluminescence of CaTiO3:Eu3+ red phosphors prepared by H3BO3 assisted solid state synthesis

    Institute of Scientific and Technical Information of China (English)

    LIU Panpan; YIN Jing; MI Xiaoyang; ZHANG Lexi; BIE Lijian

    2013-01-01

    CaTiO3:Eu3+ red phosphors were prepared using H3BO3 assisted solid state synthesis.The structure and morphology of the obtained sample were observed by X-ray diffraction (XRD) and scanning electron microscopy (SEM).And the luminescence property was measured using photoluminescence excitation (PLE) and photoluminescence (PL) spectra,respectively.In the excitation spectra,main excitation peaks of the prepared samples were centered at 397 and 465 nm,revealing that these phosphors could be excited by commercial GaN-and InGaN-typed light emitting diodes (LEDs).Dominant emission peaks of the phosphors were located at 616 nm,owing to the transition of 5D0→7F2 of Eu3+.In the optimum condition,CaTiO3:3%Eu3+ phosphor was obtained at a sintering temperature of 1200 C in air with a content of 20 mol.% H3BO3 addition.When excited by 397 nm irradiation,the PL intensity of as-prepared red phosphor was 2.2 times higher than that of samples obtained by traditional solid state synthesis,while the PL intensity was 3 times higher than that excited by 465 nm irradiation.The added H3BO3 improved the crystallinity,and increased the color purity,implying the potential to be a promising red phosphor in white light emitting diodes (WLEDs).

  12. Impedance spectroscopy studies on lead free (Ba0.85Ca0.15(Ti0.9Zr0.1O3 ceramics

    Directory of Open Access Journals (Sweden)

    Ahcène Chaouchi

    2012-12-01

    Full Text Available The AC complex impedance spectroscopy technique has been used to obtain the electrical parameters of polycrystalline sample of (Ba0.85Ca0.15(Ti0.9Zr0.1O3 in a wide frequency range at different temperatures. This sample was prepared by a high temperature solid-state reaction technique and single phase formation was confirmed by X-ray diffraction technique. This study was carried out by the means of simultaneous analysis of impedance, modulus, and electrical conductivity. The Cole-Cole (Nyquist plots suggest that the grains and grain boundaries are responsible in the conduction mechanism of the material at high temperature. The ColeCole (Nyquist plot studies revealed the presence of grain and grain boundary effect at 485 °C. On the other hand, it showed only the presence of grain boundary component of the resistivity at 535 °C. Complex impedance analysis indicated the presence of non-Debye type dielectric relaxation. The bulk resistance of the material decreases with rise in temperature similar to a semiconductor, and the Cole-Cole (Nyquist plot showed the negative temperature coefficient of resistance (NTCR character of (Ba0.85Ca0.15(Ti0.9Zr0.1O3. The value of activation energy is found to be 0.7433 eV, which suggests that the conduction may be the result of defect and charge carriers present in the materials.

  13. Influence of CaCO3, Al2O3, and TiO2 microfillers on physico-mechanical properties of Luffa cylindrica/polyester composites

    Directory of Open Access Journals (Sweden)

    Vinay Kumar Patel

    2016-06-01

    Full Text Available The development of natural fibre reinforced polymer composites has gained popularity in many applications due to their environment friendly characteristics over the synthetic fibre based polymer composites. This paper describes the fabrication and physical, mechanical, three-body abrasive wear and water absorption behaviour of Luffa fibre reinforced polyester composites with and without addition of micro-fillers of Al2O3, CaCO3 and TiO2. The ranking of the composite materials has been made by using Technique for order preference by similarity to ideal solution (TOPSIS method with output parameters of their physical, mechanical and abrasive wear and water absorption attributes. The addition of microfillers has enhanced greatly the physical and mechanical properties of Luffa-fibre based composites. The addition of microfillers has influenced the physico-mechanical properties of Luffa-fibre based polyester composites in descending order of CaCO3, Al2O3, and TiO2.

  14. Extremely large electronic anisotropy caused by electronic phase separation in Ca3(Ru0.97Ti0.03)2O7 single crystal

    Science.gov (United States)

    Peng, Jing; Wu, Xiaoshan; Mao, Zhiqiang

    2015-03-01

    Bilayered ruthenate Ca3 Ru2O7 exhibits rich electronic and magnetic properties. It orders at 56K, with FM bilayers antiferromagnetically coupled along c-axis (AFM-a). The AFM transition is closely followed by a first-order metal-insulator (MI) transition at 48K where spin directions switch to the b-axis (AFM-b). While this MI transition is accompanied by the opening of anisotropic charge gap; small Fermi pockets survive from the MI transition, thus resulting in quasi-2D metallic transport behavior for Tinsulating state with a nearest-neighbor AFM order via Ti doping. Ca3(Ru0 . 97 Ti0 . 03) 2O7 is close to the critical composition for the AFM-b-to-G-AFM phase transition. Our recent studies show the sample with this composition is characterized by an electronic phase separation between the insulating G-AFM phase (major) and the localized AFM-b phase (minor). The minor AFM-b phase forms a conducting path through electronic percolation within the ab-plane, but not along the c-axis, thus resulting in extremely large electronic anisotropy with ρab /ρc ~109 , which may be the largest among bulk materials.

  15. Dielectric and ferroelectric properties of Sr4CaSmTi3Nb7O30 with tetragonal tungsten bronze structure

    Science.gov (United States)

    Gong, Gao-Shang; Fang, Yu-Jiao; Huang, Shuai; Yin, Chong-Yang; Yuan, Song-Liu; Wang, Li-Guang

    2014-09-01

    Sr4CaSmTi3Nb7O30 ceramics are synthesized and indexed as tetragonal tungsten bronze structure. The dielectric behavior and ferroelectric nature are investigated. Three dielectric anomalies are observed. The phase transition is a displacive phase transition with some diffusive characteristics, which indicates possible compositional variations within the materials on the microscopic scale. The weak distortion disappears in cooling process for differential scanning calorimetry measurement, and the large depression of Curie—Weiss temperature T0 indicates the difficulty in forming macroferroelectric domain. The ferroelectric nature in these filled tungsten bronze niobates originates from the off-center displacement of B-site cations, but they are primarily dominated by A-site cation occupation. Both the radius and the valence of A1-site cations play an important role on ferroelectric properties of the filled tungsten bronze compounds. Existence of spontaneous polarization with a remanent polarization of 0.16 μC/cm2 a coercive field of Ec = 11.74 kV/cm confirms the room-temperature ferroelectric nature of Sr4CaSmTi3Nb7O30 ceramics.

  16. Comparative Study Between GGA and LDA Approximation Using First- Principles Calculations of Structural, Electronic, Optical and Vibrational Properties of CaTiO3 Crystal

    Science.gov (United States)

    Medeiros, Subenia; Araujo, Maeva

    2015-03-01

    The structural, electronic, vibrational, and optical properties of perovskite CaTiO3 in the cubic, orthorhombic, and tetragonal phase are calculated in the framework of density functional theory (DFT) with different exchange-correlation potentials by CASTEP package. The calculated band structure shows an indirect band gap of 1.88 eV at the Γ-R points in the Brillouin zone to the cubic structure, a direct band gap of 2.41 eV at the Γ- Γ points to the orthorhombic structure, and an indirect band gap of 2.31 eV at theM - Γ points to the tetragonal phase. It is still known that the CaTiO3 has a static dielectric constant that extrapolates to a value greater than 300 at zero temperature, and the dielectric response is dominated by low frequency (ν ~ 90cm-1) polar optical modes in which cation motion opposes oxygen motion. Our calculated lattice parameters, elastic constants, optical properties, and vibrational frequencies are found to be in good agreement with the available theoretical and experimental values. The results for the effective mass in the electron and hole carriers are also presented in this work.

  17. Development of TiO2 electrical insulation coating on Ag-alloy sheathed Bi2Sr2CaCu2O8-x round-wire

    Science.gov (United States)

    Kandel, H.; Lu, J.; Jiang, J.; Chen, P.; Matras, M.; Craig, N.; Trociewitz, U. P.; Hellstrom, E. E.; Larbalestier, D. C.

    2015-03-01

    We have developed TiO2 coating on Ag-alloy sheathed Bi2Sr2CaCu2O8-x (Bi-2212) round-wire conductor for electrical insulation in Bi-2212 magnets. The green coating has a base layer comprised of TiO2, polyvinyl butyral (PVB) and a small amount of polysilicate and a top layer made of polyacrylic. The coating was applied on the conductor using a continuous reel-to-reel dip coating process and showed very good adherence and flexibility that is suitable for magnet coil winding. The thickness of the coating is a function of slurry viscosity, wire withdrawal speed and wire radius. Small test coils were built with the coated Bi-2212 round-wires and were heat treated at 100 atm pressure. During the heat treatment, the PVB and polyacrylic were removed from the green coating and the polysilicate decomposed to SiO2 that served as a sintering aid for TiO2. After the heat treatment, the coating remained strongly adhered to the conductor and did not have a detrimental effect on the critical current (Ic) values. The breakdown voltage was about 150 V across a 7 μm thick heat treated coating on Bi-22112 round-wire conductor, corresponding to a dc dielectric strength of about 21 MV m-1.

  18. Magnetic behavior of La2/3Ca1/3MnO3 / BaTiO3 bilayers

    Science.gov (United States)

    Ordonez, John E.; Gomez, Maria E.; Lopera, Wilson; Marin, Lorena; Pardo, Jose A.; Morellon, Luis; Algarabel, Pedro; Prieto, Pedro

    2013-03-01

    We have grown ferroelectric BaTiO3(BTO) and ferromagnetic La2/3Ca1/3MnO3 (LCMO) onto (001) SrTiO3 and Nb:SrTiO3 by pulsed laser deposition (PLD) at pure oxygen atmosphere, and a substrate temperature of 820° C, seeking for a multiferroic behavior in this structure. From x-ray diffraction (XRD) we found lattice parameter aBTO=4.068 Å, and aLCMO=3.804 Å, for each individual layer. In the BTO/LCMO bilayer, (002)-Bragg peak for BTO maintain its position whereas (002) LCMO peak shift to lower Bragg angle indicating a strained LCMO film. Magnetization measurements reveal an increase in the Curie temperature from 170 K to 220 K for the bilayer when LCMO (t = 47 nm) is deposited on BTO (t=52 nm) film, while depositing the BTO (50 nm) above LCMO (48 nm) the Curie temperature remains at values close to that obtained for a LCMO single layer (~175 K), deposited under identical growth parameters This work has been supported by Instituto de Nanociencias de Aragón, Zaragoza, Spain, ``El Patrimonio Autónomo Fondo Nacional de Financiamiento para CT&I FJC'' COLCIENCIAS-CENM Contract RC 275-2011 and Research Project COLCIENCIAS-UNIVALLE.

  19. Texture design for microwave dielectric (Ca0.7Nd0.3)0.87TiO3 ceramics through reactive-templated grain growth

    Science.gov (United States)

    Tani, Toshihiko; Takeuchi, Tsuguto

    2015-06-01

    Plate-like Ca3Ti2O7 (CT) and Nd2Ti2O7 (NT) particles were synthesized in molten salts and used as reactive templates for the preparation of highly textured (Ca0.7Nd0.3)0.87TiO3 bulk ceramics (CNT) with preferred pseudocubic and orientations, respectively. During flux growth CT and NT particles developed facets parallel to the pseudocubic {100} and {110} planes, respectively, in a perovskite unit cell, since those planes correspond to the interlayers of the layered perovskite-type crystal structures. Complementary reactants for the CNT stoichiometry were wet-mixed with the reactive templates and the slurries were tape-cast. Then stacked tapes were heat-treated for dense single-phase CNT ceramics with a distorted and A-site deficient regular perovskite-type structure. The CNT ceramics prepared with CT and NT reactive templates exhibited strong pseudocubic 100- and 110-family x-ray diffraction peaks, respectively, with other peaks drastically suppressed when non-perovskite sources were used as complementary reactants. The textured ceramics possess unique microstructures; as either parallel or obliquely stacked block structures with a pseudocubic {100} plane faceted. The pseudocubic {100}-and {110}-textured CNT ceramics exhibited ∼10 and ∼20% higher products of the dielectric quality factor and frequency, Q · f, respectively, than conventional ceramic sintered at the same temperature. When Q · f is compared based on the same grain size, the {100}-textured CNT exhibited 27% higher values than non-textured while relative permittivity and temperature coefficient of resonant frequency were of similar values. Simple geometrical relationships between electric field and penetrated pseudocubic {hk0}-type grain boundaries must lead to the reduced scattering and dielectric loss.

  20. Structure, tribocorrosion and biocide characterization of Ca, P and I containing TiO{sub 2} coatings developed by plasma electrolytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Sáenz de Viteri, V., E-mail: virginia.saenzdeviteri@tekniker.es [IK4-Tekniker, Polo Tecnológico de Eibar, Calle Iñaki Goenaga, 5, Eibar 20600 (Spain); Bayón, R.; Igartua, A. [IK4-Tekniker, Polo Tecnológico de Eibar, Calle Iñaki Goenaga, 5, Eibar 20600 (Spain); Barandika, G. [Departamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco, UPV/EHU, Apartado 644, Bilbao E-48080 (Spain); Moreno, J. Esteban; Peremarch, C. Pérez-Jorge; Pérez, M. Martínez [Department of Clinical Microbiology, IIS-Fundación Jiménez Díaz, Av. Reyes Católicos 2, Madrid 28040 (Spain)

    2016-03-30

    Graphical abstract: - Highlights: • Ca, P and I doped TiO{sub 2} coatings were developed by means of plasma electrolytic oxidation (PEO) technique. • Microstructure and chemical composition of the developed coating were in depth analyzed. • The effect of wear-corrosion synergy was studied through tribocorrosion tests. • Antibacterial efficiency of iodine as biocide agent was analyzed by means of bacterial adhesion study. • A TiO{sub 2} coating with improved wear-corrosion resistance, suitable surface for cell adhesion and biocide properties was achieved. - Abstract: In hip joint implants, in particular in the stems, wear-corrosion effects can accelerate the degradation of the biomaterial. The lack of osseointegration and the risk of contracting implant-associated infections may be other reasons for a premature failure of the implant. In this work, TiO{sub 2} coatings have been developed by means of plasma electrolytic oxidation (PEO) technique in order to achieve wear-resistant hard coatings with osseointegration ability and biocide characteristics. During the PEO process, elements that favor cell growth, like Ca and P, were introduced into the coating. With the purpose of providing the coating with antibacterial properties iodine was added like biocide agent. The microstructure and chemical composition of the developed coatings were analyzed in order to see if the surface of the films was suitable for the cell attachment. The effect of wear-corrosion synergy was studied by means of tribocorrosion tests. Finally, the biocide capacity of iodine against Staphylococcus aureus and Staphylococcus epidermidis was analyzed through bacterial adhesion tests. High wear and corrosion resistance was shown in one of the developed coatings. The achieved surface microstructures seem to be appropriate to improve the osseointegration with proper pore size and porosity index. The antibacterial capacity of iodine was confirmed for S. epidermidis.

  1. Texture design for microwave dielectric (Ca0.7Nd0.3)0.87TiO3 ceramics through reactive-templated grain growth.

    Science.gov (United States)

    Tani, Toshihiko; Takeuchi, Tsuguto

    2015-06-01

    Plate-like Ca3Ti2O7 (CT) and Nd2Ti2O7 (NT) particles were synthesized in molten salts and used as reactive templates for the preparation of highly textured (Ca0.7Nd0.3)0.87TiO3 bulk ceramics (CNT) with preferred pseudocubic 〈100〉 and 〈110〉 orientations, respectively. During flux growth CT and NT particles developed facets parallel to the pseudocubic {100} and {110} planes, respectively, in a perovskite unit cell, since those planes correspond to the interlayers of the layered perovskite-type crystal structures. Complementary reactants for the CNT stoichiometry were wet-mixed with the reactive templates and the slurries were tape-cast. Then stacked tapes were heat-treated for dense single-phase CNT ceramics with a distorted and A-site deficient regular perovskite-type structure. The CNT ceramics prepared with CT and NT reactive templates exhibited strong pseudocubic 100- and 110-family x-ray diffraction peaks, respectively, with other peaks drastically suppressed when non-perovskite sources were used as complementary reactants. The textured ceramics possess unique microstructures; as either parallel or obliquely stacked block structures with a pseudocubic {100} plane faceted. The pseudocubic {100}-and {110}-textured CNT ceramics exhibited ∼10 and ∼20% higher products of the dielectric quality factor and frequency, Q · f, respectively, than conventional ceramic sintered at the same temperature. When Q · f is compared based on the same grain size, the {100}-textured CNT exhibited 27% higher values than non-textured while relative permittivity and temperature coefficient of resonant frequency were of similar values. Simple geometrical relationships between electric field and penetrated pseudocubic {hk0}-type grain boundaries must lead to the reduced scattering and dielectric loss.

  2. 结合长度对悬浮液中电子注射效率和CA (Carotenoic Acid)-TiO2纳米粒子体系构成的太阳能电池中太阳能转化成电能的效率的依赖性%Conjugation-length Dependence of Electron-injection Efficiency in Suspensions and Solar-energy to Electricity Conversion Efficiency in Solar Cells, Consisting of the Carotenoic Acid-TiO2 Nano-particle Systems

    Institute of Scientific and Technical Information of China (English)

    Yasushi; Koyama; JunFeng; Xiang; XiaoFengWang

    2005-01-01

    @@ The electron-injection mechanisms determined for TiO2-carotenoic acid (CA) suspensions. Subpicosecond time-resolved absorption spectra were recorded for retinoic and carotenoic acids, I.e., RA5, CA6, CA7, CA8, CA9 and CA11 (hereafter, collectively referred to ‘Cas’) having the number of conjugated double bonds,n = 5, 6, 7, 8, 9 and 11, respectively, free in ethanol solution and bound to TiO2 nano-particles.

  3. Toxic effects of TiO2 nanoparticles in primary cultured rat sertoli cells are mediated via a dysregulated Ca(2+) /PKC/p38 MAPK/NF-κB cascade.

    Science.gov (United States)

    Ye, Lingqun; Hong, Fashui; Ze, Xiao; Li, Lingjuan; Zhou, Yaoming; Ze, Yuguan

    2017-02-11

    Although numerous studies have demonstrated that titanium dioxide nanoparticles (TiO2 NPs) can be accumulated in various animal organs and can cause toxicity, there is currently only limited data regarding reproductive toxicity especially on the toxic mechanisms of TiO2 NPs in Sertoli cells. In order to investigate the mechanism of reproductive toxicity, primary cultured rat Sertoli cells were exposed to 5, 15, or 30 μg/mL TiO2 NPs for 24 h, and TiO2 NPs internalization, expression of PKC (p-PKC) and p38 MAPK (p-p38 MAPK) as well as calcium homeostasis were examined. Our findings demonstrated that TiO2 NPs crossed the membrane into the cytoplasm or nucleus, and significantly suppressed cell viability of primary cultured rat Sertoli cells in a concentration-dependent manner. Furthermore, immunological dysfunction caused by TiO2 NPs was involved in the increased expression of NF-κB, TNF-α, and IL-1β, and decreased IκB expression. TiO2 NPs significantly decreased Ca(2+) -ATPase and Ca(2+) /Mg(2+) -ATPase activity and enhanced intracellular Ca(2+) levels, and up-regulated the expression of p-PKC and p-p38 MAPK in a dose-dependent manner in primary cultured rat Sertoli cells. Taken together, these findings indicate that TiO2 NPs may induce immunological dysfunction of primary cultured rat Sertoli cells by stimulating the Ca(2+) /PKC/p38 MAPK cascade, which triggers NF-κB activation and ultimately induces the expression of inflammatory cytokines in primary cultured rat Sertoli cells. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2017.

  4. Cyclotron production of {sup 43}Sc for PET imaging

    Energy Technology Data Exchange (ETDEWEB)

    Walczak, Rafał [Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw (Poland); Krajewski, Seweryn [Synektik S.A., Research and Development Center, Warsaw (Poland); Szkliniarz, Katarzyna [Department of Nuclear Physics, University of Silesia, Katowice (Poland); Sitarz, Mateusz [Heavy Ion Laboratory, University of Warsaw, Warsaw (Poland); Abbas, Kamel [Nuclear Security Unit, Joint Research Centre, Institute for Transuranium Elements, European Commission, Ispra (Italy); Choiński, Jarosław; Jakubowski, Andrzej; Jastrzębski, Jerzy [Heavy Ion Laboratory, University of Warsaw, Warsaw (Poland); Majkowska, Agnieszka [Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw (Poland); Simonelli, Federica [Nuclear Decommissioning Unit, Joint Research Centre, Ispra Site Management Directorate, European Commission, Ispra (Italy); Stolarz, Anna; Trzcińska, Agnieszka [Heavy Ion Laboratory, University of Warsaw, Warsaw (Poland); Zipper, Wiktor [Department of Nuclear Physics, University of Silesia, Katowice (Poland); Bilewicz, Aleksander [Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw (Poland)

    2015-12-04

    Recently, significant interest in {sup 44}Sc as a tracer for positron emission tomography (PET) imaging has been observed. Unfortunately, the co-emission by {sup 44}Sc of high-energy γ rays (E{sub γ} = 1157, 1499 keV) causes a dangerous increase of the radiation dose to the patients and clinical staff. However, it is possible to produce another radionuclide of scandium—{sup 43}Sc—having properties similar to {sup 44}Sc but is characterized by much lower energy of the concurrent gamma emissions. This work presents the production route of {sup 43}Sc by α irradiation of natural calcium, its separation and purification processes, and the labeling of [DOTA,Tyr3] octreotate (DOTATATE) bioconjugate. Natural CaCO{sub 3} and enriched [{sup 40}Ca]CaCO{sub 3} were irradiated with alpha particles for 1 h in an energy range of 14.8–30 MeV at a beam current of 0.5 or 0.25 μA. In order to find the optimum method for the separation of {sup 43}Sc from irradiated calcium targets, three processes previously developed for {sup 44}Sc were tested. Radiolabeling experiments were performed with DOTATATE radiobioconjugate, and the stability of the obtained {sup 43}Sc-DOTATATE was tested in human serum. Studies of {sup nat}CaCO{sub 3} target irradiation by alpha particles show that the optimum alpha particle energies are in the range of 24–27 MeV, giving 102 MBq/μA/h of {sup 43}Sc radioactivity which creates the opportunity to produce several GBq of {sup 43}Sc. The separation experiments performed indicate that, as with {sup 44}Sc, due to the simplicity of the operations and because of the chemical purity of the {sup 43}Sc obtained, the best separation process is when UTEVA resin is used. The DOTATATE conjugate was labeled by the obtained {sup 43}Sc with a yield >98 % at elevated temperature. Tens of GBq activities of {sup 43}Sc of high radionuclidic purity can be obtainable for clinical applications by irradiation of natural calcium with an alpha beam.

  5. A percepção dos gestores operacionais sobre os impactos gerados nos processos de trabalho após a implementação das melhores práticas de governança de TI no TRE/SC

    Directory of Open Access Journals (Sweden)

    Rosangela Klumb

    2014-08-01

    Full Text Available Este estudo objetivou compreender a percepção dos gestores operacionais da Secretaria de Tecnologia da Informação (STI do TRE/SC acerca dos impactos gerados nos processos de trabalho internos do órgão após a implementação das melhores práticas de governança de TI. Em termos metodológicos, trata-se de um estudo de caso descritivo-avaliativo, de abordagem qualitativa no que concerne às características e ao modo de investigação. Como resultados, verificou-se que até março de 2013 foram implementados oito dos 24 processos de governança de TI baseados no modelo Cobit, versão 4.1, definidos como meta do Planejamento Estratégico de TI para 2013. Concluiu-se que a percepção dos gestores é positiva em relação à governança de TI, embora existam algumas falhas, como na comunicação intra e interáreas e na centralização de informações por alguns setores.

  6. Fotoluminescência e adsorção de CO2 em nanopartículas de CaTiO3 dopadas com lantânio

    Directory of Open Access Journals (Sweden)

    Gonçalves Rosana F.

    2004-01-01

    Full Text Available Ca1-xLa xTiO3 powders were prepared by the polymeric precursor method. X-ray diffraction (XRD, FT-Raman spectroscopy, transmission electron microscopy (TEM, and N2 and CO2 adsorption were used for the microstructural and surface characterization of the powders. Room temperature photoluminescence (PL was observed in Ca1-xLa xTiO3 amorphous particles. The PL intensity of these powders was found to be dependent on the lanthanum molar concentration.

  7. Synthesis and characterization of gelatin-CaO-SiO2-TiO2 bioactive hybrid applied in bone repairing%应用于骨修复的明胶-CaO-SiO2-TiO2生物活性杂化材料的合成及其性能

    Institute of Scientific and Technical Information of China (English)

    殷海荣; 武丽华; 丁纪根; 赵高扬; 张光华

    2007-01-01

    BACKGROUND: It has been reported that bioactivity is found to be favored by the co-operative behavior of silanol (Si-OH)or Ti-OH etc. groups on the material surface and the involved calcium ions. To confirm the hypothesis that a new family of organic-inorganic hybrid materials, which incorporate gelatin chains covalently into Si-O-Ti network, is synthesized through sol-gel procedure.OBJECTIVE: To synthesize a hybrid of gelatin and CaO-SiO2-TiO2 system which is used for bone repairing, and observe its structure and bioactivity.DESIGN: Randomized control observation.SETTING; the laboratory, School of Material Science and Engineering, Shaanxi University of Science and Technology. MATERIALS: Gelatin (Sinopharm Chemical Reagent Co., Ltd), titanic acid isopropyl ester (Gu'an Hengye Fine Chemicals Co., Ltd), γ-glycidoxy propyl trimethoxy silane (Jingzhou Jianghan Fine Chemicals Co., Ltd), calcium nitrate (Tianjin Bodi Chemicals Co., Ltd)METHODS: The experiment was carried out in the laboratory, School of Materials Sciences and Engineering, Shaanxi University of Science and Technology between April and August in 2006. A new type of bioactive organic-inorganic hybrid was synthesized through sol-gel processing starting from gelatin, γ-(2,3-glycidoxypropyl)trimethoxysilane (GPSM),Tetraisopropyltitanate (TiPT) and calcium nitrate. ①Structure of the hybrid: The structures of the products were investigated with Fourier transformed infrared (FT-IR) diffusive reflection spectroscope, X-ray diffraction (XRD) instrument and scanning electron microscope (SEM) respectively.②Bioactivity: The products Ti15Ca0 and Ti15Ca20 were soaked in a stimulated body fluid (SBF) to evaluate the morphology of the surfaces by SEM and thin-film XRD. MAIN OUTCOME MEASURES: The structure and bioactivity of the hybrid.RESULTS: ①The hybrid was completely amorphous and its surface was almost homogenous, which implied the covalent bonding between the organic component and inorganic component. FT

  8. 热化学法制备CaTiO3涂层及涂层的生物相容性%Biocompatibility of calcium-titanate coating prepared by thermochemical treatment

    Institute of Scientific and Technical Information of China (English)

    黄晶; 蓝琳; 肖东琴; 罗会涛; 智伟; 段可; 翁杰; 张聪

    2011-01-01

    背景:钛酸钙(CaTiO3)作为一种有前途的涂层,应用于钛基医用植入体表面.目的:通过一种简单的热化学处理技术,Ti6Al4V基体上制备均匀的CaTiO3涂层,时通过培养成骨细胞观察涂层生物相容性.方法:通过将Ti6Al4V基体埋于无水硝酸钙(Ca(NO3)2)粉末中,且升高温度;当温度处在Ca(NO3)2熔点以上时,Ti6Al4V基体上能够生成一层均匀的CaTiO3层.同时在热化学处理温度为570 ℃的Ti6Al4V基体材料上进行成骨细胞培养,察所制备涂层的生物相容性.结果与结论:该涂层转化只有在Ca(NO3)2熔点(561 ℃)以上时才会发生,时随着处理温度的升高,aTiO3晶体尺寸随之增大;经过热化学处理后的样品具有良好的生物相容性,成骨细胞黏附、增殖具有更好的促进作用.该方法简单、有效,制备的涂层具有良好的生物相容性,望在钛植入体表面处理中获得应用,提高金属表面与细胞、组织的相容性.%BACKGROUND:Calcium-titanate (CaTiO3) is a promising coating candidate on titanium biomedical implants.OBJECRIVE:To prepare uniform CaTiO3 coatings on Ti6Al4V substrates by a simple thermochemical surface transformation technique and to evaluate its biocompatibility by in vitro culture of rat osteoblasts.METHODS:Ti6Al4V substrates were embedded in anhydrous calcium nitrate powders and the temperature was increased;reaction between the molten nitrate and Ti6Al4V formed a uniform layer of calcium nitrate. The biocompatibility of Ti6Al4V thermochemically treated at 570 ℃ was evaluted by in vitro culture of SD rat osteoblasts.RESULTS AND CONCLUSION:The transformation occurred only above the melting point of anhydrous calcium nitrate (561 ℃),and that the size of the calcium titanate crystals increased with the treatment temperature. Proliferation and adhesion of osteoblasts was promoted on the thermochemically treated substrates. This technique is simple and efficient, and may find applications in the

  9. Study on the "Negative" Resistance Switching Properties in Ti/La_(0.7)Ca_(0.3)MnO_3/Pt Sandwiches Devices%Ti/La_(0.7)Ca_(0.3)MnO_3/Pt结构器件中"负"电阻开关特性研究

    Institute of Scientific and Technical Information of China (English)

    刘新军; 李效民; 王群; 杨蕊; 曹逊; 陈立东

    2010-01-01

    以Pt/Ti/SiO_2/Si为衬底,制备了具有电阻转变特性的Ti/La_(0.7)Ca_(0.3) MnO(LCMO)/Pt结构器件.X射线衍射分析表明LCMO薄膜呈纳米晶或非晶态,扫描电子显微镜及原子力显微镜分析表明LCMO薄膜表面平整、光滑致密.电学测试结果表明Ti/LCMO/Pt结构具有明显的双极型"负"电阻转变特性,低电阻态的导电过程为空间电荷限制电流机制,高电阻态的导电过程为Poole-Frenkel发射机制.利用氧化还原反应的随机性和TiO_x中间层空间分布的不均匀性,定性地解释了高电阻态的不稳定性以及电流一电压曲线上的电流突变现象.

  10. Phase evolution studies in CaZrTi{sub 2}O{sub 7}−RE{sub 2}Ti{sub 2}O{sub 7} (RE = Nd{sup 3+}, Sm{sup 3+}) system: Futuristic ceramic host matrices for nuclear waste immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Jafar, M., E-mail: sachary@barc.gov.in; Achary, S. N., E-mail: sachary@barc.gov.in; Tyagi, A. K., E-mail: sachary@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Mumbai-400085 (India)

    2014-04-24

    Series of compositions with general stoichiometry as Ca{sub 1−x}Zr{sub 1−x}RE{sub 2x}Ti{sub 2}O{sub 7} (RE = Nd{sup 3+}, Sm{sup 3+}) were prepared by solid state reaction and characterized by powder x-ray diffraction technique to unravel the phase fields in the title systems. The phase fields in CaZrTi{sub 2}O{sub 7−}Nd{sub 2}Ti{sub 2}O{sub 7} and CaZrTi{sub 2}O{sub 7−}Sm{sub 2}Ti{sub 2}O{sub 7} systems differed significantly at the rareearth rich regions. The common phase fields like zirconolite-2M, zirconolite-4M, cubic perovskite are observed at the zirconolite rich regions of both systems. Depending on the structure of RE{sub 2}Ti{sub 2}O{sub 7} phase, the cubic pyrochlore or monoclinic RE{sub 2}Ti{sub 2}O{sub 7} phases are observed in the studied system. The observed phase fields in these two systems indicate ionic radius of the rare-earth ion has a dominating role in the phase relations. Further details of the phases and their homogeneity are explained in the text of the manuscript.

  11. Preparation and characterization of segmented p-type Ti0.3Zr0.35Hf0.35CoSb0.8Sn0.2/Ca3Co4O9

    DEFF Research Database (Denmark)

    Le, Thanh Hung; Han, Li; Stamate, Eugen;

    Misfit-layered cobaltite Ca3Co4O9+δ is considered as good p-type thermoelectric material in high temperature region (950 - 1100 K), while half-Heusler (HH) Ti0.3Zr0.35Hf0.35CoSb0.8Sn0.2 is high performance p-type material at temperatures below 950 K. In this work, oxide Ca3Co4O9+δ is segmented...

  12. Observation of indium ion migration-induced resistive switching in Al/Mg0.5Ca0.5TiO3/ITO

    Science.gov (United States)

    Lin, Zong-Han; Wang, Yeong-Her

    2016-08-01

    Understanding switching mechanisms is very important for resistive random access memory (RRAM) applications. This letter reports an investigation of Al/Mg0.5Ca0.5TiO3 (MCTO)/ITO RRAM, which exhibits bipolar resistive switching behavior. The filaments that connect Al electrodes with indium tin oxide electrodes across the MCTO layer at a low-resistance state are identified. The filaments composed of In2O3 crystals are observed through energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, nanobeam diffraction, and comparisons of Joint Committee on Powder Diffraction Standards (JCPDS) cards. Finally, a switching mechanism resulting from an electrical field induced by In3+ ion migration is proposed. In3+ ion migration forms/ruptures the conductive filaments and sets/resets the RRAM device.

  13. Fabrication, Sintering and Electrical Properties of (Ca0.61,Nd0.26)TiO3 Nanoparticles Doped with Li-Cu-B

    Institute of Scientific and Technical Information of China (English)

    Fei Wu; Qilong Zhang; Hui Yang

    2011-01-01

    A sol-gel processing was used to synthesize (Ca0.61,Nd0.26)TiO3 (CNT) nanoparticles doped with Li-Cu-B at low temperature. Orthorhombic perovskite structure phase with a small amount of Li3BO3 secondary phase was formed by calcining the xerogels at 300℃, and monodisperse CNT nano-powders with the grain size of 10-15 nm could be obtained. By using these nanocrystalline CNT powders, dense CNT ceramics could be achieved at the low sintering temperature of 1100℃ due to the effect of the small size nanoparticles and liquid phase Li3BO3. And the dielectric properties with dielectric constant (εr= 89.52), quality value factors with frequency (Q×f=17148 GHz) and the temperature coefficient of resonant frequency (Tf) value of +239× 10-6/℃ were achieved.

  14. Dielectric behaviour of (Ba0.77Ca0.23(Ti0.98Dy0.02O3 ceramics

    Directory of Open Access Journals (Sweden)

    Abdul Moquim

    2015-06-01

    Full Text Available In this study, BaTiO3 is modified with Ca2+ and in addition doped with Dy3+ at the B site lattice. The main idea is to search for new lead-free ferroelectric material and improve their properties. For this purpose, the barium calcium titanate (BCT as a host and the rare earth element Dy3+ as an activator were used to fabricate a multifunctional material. The obtained ceramics was found to be homogeneous, dense and a single phase material with no evidence of secondary phases. The dielectric study showed that TC increases with the addition of dopants and the obtained ceramics behaves like a relaxor ferroelectric. Some important structural parameters and dielectric properties of dysprosium modified barium (calcium titanate ceramics are presented.

  15. Competing strain relaxation mechanisms in epitaxially grown Pr0.48Ca0.52MnO3 on SrTiO3

    Directory of Open Access Journals (Sweden)

    Anja Herpers

    2014-10-01

    Full Text Available We investigated the impact of strain relaxation on the current transport of Pr0.48Ca0.52MnO3 (PCMO thin films grown epitaxially on SrTiO3 single crystals by pulsed laser deposition. The incorporation of misfit dislocations and the formation of cracks are identified as competing mechanisms for the relaxation of the biaxial tensile strain. Crack formation leads to a higher crystal quality within the domains but the cracks disable the macroscopic charge transport through the PCMO layer. Progressive strain relaxation by the incorporation of misfit dislocations, on the other hand, results in a significant decrease of the activation energy for polaron hopping with increasing film thickness.

  16. Experimental and numerical investigation of a ceramic dielectric resonator (DRA): CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO)

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, A.F.L. [Departamento de Fisica, Universidade do Aveiro, 3800-193 Aveiro (Portugal); Mestrado em Ciencias Fisicas Aplicadas, Universidade Estadual do Ceara, Campus do Itaperi 1700, CEP 60740-903 Fortaleza, Ceara (Brazil); Laboratorio de Telecomunicacoes e Ciencia e Engenharia dos Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, CEP 60455-760 Fortaleza, Ceara (Brazil); Silva, R.R. [Laboratorio de Telecomunicacoes e Ciencia e Engenharia dos Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, CEP 60455-760 Fortaleza, Ceara (Brazil); Rocha, H.H.B. [Laboratorio de Telecomunicacoes e Ciencia e Engenharia dos Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, CEP 60455-760 Fortaleza, Ceara (Brazil); Departamento de Engenharia de Teleinformatica (DETI), Universidade Federal do Ceara, Caixa Postal 6007, CEP 60.755-640 Fortaleza, Ceara (Brazil); Fechine, P.B.A. [Laboratorio de Telecomunicacoes e Ciencia e Engenharia dos Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, CEP 60455-760 Fortaleza, Ceara (Brazil); Departamento de Quimica Analitica e Fisico-Quimica, Universidade Federal do Ceara - UFC, Campus do Pici, CP 12100, CEP 60451-970 Fortaleza - CE (Brazil); Cavalcanti, F.S.A. [Mestrado em Ciencias Fisicas Aplicadas, Universidade Estadual do Ceara, Campus do Itaperi 1700, CEP 60740-903 Fortaleza, Ceara (Brazil); Valente, M.A. [Departamento de Fisica, Universidade do Aveiro, 3800-193 Aveiro (Portugal); Freire, F.N.A.; Sohn, R.S.T.M. [Laboratorio de Telecomunicacoes e Ciencia e Engenharia dos Materiais (LOCEM), Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, CEP 60455-760 Fortaleza, Ceara (Brazil)] (and others)

    2008-03-01

    In this study, the CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) ceramic phase was synthesized by microwave heating in a much shorter time compared to the conventional heating methods. The results indicate that microwave processing is a promising method for preparing CCTO ceramics. CCTO was prepared using a domestic microwave oven operated at 2.45 GHz with 800 W. After a few minutes of microwave irradiation the formation of CCTO was confirmed by X-ray powder diffraction. The CCTO ceramic was studied in the medium-frequency (MF) range (100 Hz-1 MHz) and in the microwave range of frequencies. The experimental and theoretical characteristics of the dielectric resonator antenna are investigated.

  17. Effect of oxygen partial pressure on structural and optical properties of pulsed laser deposited CaBi4Ti4O15 thin films

    Science.gov (United States)

    Emani, Sivanagi Reddy; Raju, K. C. James

    2017-03-01

    The influence of oxygen partial pressure (OPP) on the structural and optical properties of CaBi4Ti4O15 (CBTi) thin films deposited by pulsed laser deposition have been investigated in the range of 0.1 mbar to 7.8 × 10-3 mbar. The structural properties show all the films are polycystlline in nature with orthorombic structure. The optical transmission of the films is in the range of 60-90%. A slight shift in transmission threshold towards higher wavelength region with an increase in O2 pressure reveals the systematic reduction in the optical band gap energy (3.69 to 3.59 eV) of the films. Raman studies confirm the phase formation and presence of stresses in the films. It is suggested that the OPP played a key role in controlling crystallinity, morphology, chemical composition and optical properties in CBTi thin films.

  18. Optical and microwave properties of CaBi4Ti4O15 ferroelectric thin films deposited by pulsed laser deposition

    Science.gov (United States)

    Emani, Sivanagi Reddy; Joseph, Andrews; Raju, K. C. James

    2016-05-01

    Transparent CaBi4Ti4O15 (CBTi) ferroelectric thin films are deposited by pulsed laser deposition method. The structural, optical and microwave dielectric properties were investigated. CBTi thin films had polycrystalline bismuth-layered perovskite structure and exhibited excellent optical properties. The X-ray analysis of the thin film demonstrates the phase formation and crystallinity. The optical transmission studies show that film is transparent in VIS-NIR region with a direct band gap of 3.53 EV. Morphological studies provide surface roughness as 3 mm. Dielectric constant and loss factors were 48 and 0.060 respectively, at 10GHz. These results suggest that CBTi thin films are promising multifunctional materials for applications in optoelectronic and microwave devices.

  19. Static current models in Co2+ and Ti4+ substituted M-type CaCoxTixFe(12-2x)O19 ferrite

    Science.gov (United States)

    Kaur, Rajneesh; Singh, Charanjeet; Bhikhan, Vikas; Jaroszewski, Maciej; Bindra Narang, S.

    2015-10-01

    The static current density ( J)-electric field ( E) characteristics of CaCo x Ti x Fe(12-2 x)O19 ferrite ( x = 0.1,0.2,0.3,0.4,0.5,0.6,0.7) have been investigated from 0.06 kV/m to 4.10 kV/m at room temperature. Ohmic behavior is present in compositions x = 0.1,0.2,0.4,0.5,0.6,0.7 at low applied field, whereas non linearity in J- E curves is defined at higher applied region in compositions x = 0.2,0.3,0.4,0.7. The role of various conduction mechanisms Schottky, Poole-Frenkel, Ionic Hopping and Space Charge Limited Current mechanisms has been discussed.

  20. Microwave dielectric properties of xCaTiO3-(1-x)LaAlO3 ceramics%xCaTiO3-(1-x)LaAlO3陶瓷微波介电性能的研究

    Institute of Scientific and Technical Information of China (English)

    方丹华; 江娟; 窦占明; 陆超; 章天金

    2015-01-01

    xCaTiO3-(1-x)LaAlO3 ceramics(CTLA,0.55≤x≤0.69)were prepared by traditional solid state process .The crystal structure,microstructure and microwave dielectric properties of the prepared CTLA ceramics were investigated .The results showed that the CTLA ceramics sintered at 1 400℃exhibited excellent microwave properties:the dielectric permittivity within the range from 35 to 47,Q × f≥35 000 GHz .The temperature coefficient of resonance frequency being near to zero with the increase of LaAlO 3 molar concentration.At x=0.67 the optimal microwave properties were obtained:εr=45,Q×f=36 684 GHz,τf=6.02×10-6/℃.%采用传统固相反应法制备xCaTiO3-(1-x)LaAlO3(0.55≤x≤0.69)(CTLA)陶瓷,研究CTLA陶瓷的物相,微观结构及微波介电性能.结果表明,烧结温度在1400℃时,陶瓷的微波性能最佳,介电常数在35~47之间,Q×f≥35000 GHz .随着CaTiO3含量的增大,频率温度系数趋零,当x=0.67时,陶瓷具有最佳的微波性能:εr=45,Q×f=36684 GHz,τf=6.02×10-6/℃.①

  1. Effects of rare earth ionic doping on microstructures and electrical properties of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Renzhong [School of Materials Science and Engineering, Xi' an University of Technology, Xi' an 710048 (China); Department of Technology and Physics, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Chen, Zhenping, E-mail: xrzbotao@163.com [Department of Technology and Physics, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Dai, Haiyang; Liu, Dewei; Li, Tao [Department of Technology and Physics, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Zhao, Gaoyang, E-mail: zhaogy@xaut.edu.cn [School of Materials Science and Engineering, Xi' an University of Technology, Xi' an 710048 (China)

    2015-06-15

    Graphical abstract: The dielectric constant decreases monotonically with reduced RE doping ion radius and is more frequency independent compared with that of pure CCTO sample. - Highlights: • The mean grain sizes decrease monotonically with reduced RE doping ionic radius. • Doping gives rise to the monotonic decrease of ϵ{sub r} with reduced RE ionic radius. • The nonlinear coefficient and breakdown field increase with RE ionic doping. • α of all the samples is associated with the potential barrier width rather than Φ{sub b}. - Abstract: Ca{sub 1–x}R{sub x}Cu{sub 3}Ti{sub 4}O{sub 12}(R = La, Nd, Eu, Gd, Er; x = 0 and 0.005) ceramics were prepared by the conventional solid-state method. The influences of rare earth (RE) ion doping on the microstructure, dielectric and electrical properties of CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) ceramics were investigated systematically. Single-phase formation is confirmed by XRD analyses. The mean grain size decreases monotonically with reduced RE ion radius. The EDS results reveal that RE ionic doping reduces Cu-rich phase segregation at the grain boundaries (GBs). Doping gives rise to the monotonic decrease of dielectric constant with reduced RE ionic radius but significantly improves stability with frequency. The lower dielectric loss of doped samples is obtained due to the increase of GB resistance. In addition, the nonlinear coefficient and breakdown field increase with RE ionic doping. Both the fine grains and the enhancement of potential barrier at GBs are responsible for the improvement of the nonlinear current–voltage properties in doped CCTO samples.

  2. Crystal micromorphologies and forming voltage effect on resistance switching behaviors in Ti/Pr(Sr{sub 0.1}Ca{sub 0.9}){sub 2}Mn{sub 2}O{sub 7}/Pt devices

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yuchen; Song, Liwei; Hua, Lifang; Cai, Wenhui; Chen, Wei [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China); Zhao, Xu, E-mail: xzhao@hebtu.edu.cn [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China)

    2015-10-15

    Two Pr(Sr{sub 0.1}Ca{sub 0.9}){sub 2}Mn{sub 2}O{sub 7} (PSCMO)-based devices (Ti/PSCMO-1/Pt and Ti/PSCMO-2/Pt) have been prepared by pulsed laser deposition, and the micromorphology of the films can be controlled through the different deposition condition. PSCMO-1 film with a smaller grain size grows with a near-random arrangement, whereas columnar grains with a larger grain size appear in the Ti/PSCMO-2/Pt device. The I–V curves in Ti/PSCMO-2/Pt device show the higher resistance ratio and larger hysteresis than that in the Ti/PSCMO-1/Pt device without forming process. The electron transport property in the PSCMO-2 film shows the higher resistance and metal behavior in room temperature. By fitting the I–V curves, we found that the conduction process in Ti/PSCMO-1/Pt device is dominated by Schottky barrier mechanism, but the conduction behavior in Ti/PSCMO-2/Pt device are dominated by trap-charged space-charge-limited current (SCLC) mechanism. Interesting, after a forming process, the Ti/PSCMO-1/Pt device also displays the higher resistance ratio and larger hysteresis, which can be explained by SCLC mechanism. Our results suggest that the crystal micromorphology and grain size may play a critical role in oxygen vacancy movement, and result in the transformation of resistance switching along with a higher resistance ratio and larger hysteresis in the Ti/PSCMO-2/Pt device. - Highlights: • Two different Pr(Sr{sub 0.1}Ca{sub 0.9}){sub 2}Mn{sub 2}O{sub 7}-based devices have been prepared. • The device with larger grain and columnar arrangement shows higher resistance ratio. • Crystal morphologies and grain size play critical role in oxygen vacancy movement.

  3. Raman spectra of the solid-solution between Rb sub 2 La sub 2 Ti sub 3 O sub 1 sub 0 and RbCa sub 2 Nb sub 3 O sub 1 sub 0

    CERN Document Server

    Kim, H J; Yun, H S

    2001-01-01

    A site preference of niobium atom in Rb sub 2 sub - sub x La sub 2 Ti sub 3 sub - sub x Nb sub x O sub 1 sub 0 (0.0<=x<=1.0) and RbLa sub 2 sub - sub x Ca sub x Ti sub 2 sub - sub x Nb sub 1 sub + sub x O sub 1 sub 0 (0.0<=x<= 2.0), which are the solid-solutions between Rb sub 2 La sub 2 Ti sub 3 O sub 1 sub 0 are RbCa sub 2 Nb sub 3 O sub 1 sub 0 , has been investigated by Raman spectroscopy. The Raman spectra of Rb sub 2 sub - sub x La sub 2 Ti sub 3 sub - sub x Nb sub x O sub 1 sub 0 (0.0<=x<=1.0) gave an evidence that niobium atoms substituted for titanium atoms preferably occupy the highly distorted outer octahedral sites rather than the central ones in triple-octahedral perovskite layers. In contrast, the Raman spectra of RbLa sub 2 sub - sub x Ca sub x Ti sub 2 sub - sub x Nb sub 1 sub + sub x O sub 1 sub 0 (0.0<=x<= 2.0) showed no clear information for the cationic arrangement in perovskite slabs. This difference indicated that a site preference of niobium atoms is observed onl...

  4. Significant increase of Curie temperature and large piezoelectric coefficient in Ba(Ti0.80Zr0.20)O3-0.5(Ba0.70Ca0.30)TiO3 nanofibers

    Science.gov (United States)

    Fu, Bi; Yang, Yaodong; Gao, Kun; Wang, Yaping

    2015-07-01

    Ba(Ti0.80Zr0.20)O3-0.5(Ba0.7Ca0.3)TiO3 (abbreviated as BTZ-0.5BCT) is a piezoelectric ceramic with a high piezoelectric coefficient d33 (˜620 pC N-1) and has been regarded as one of the most promising candidates to replace PZT-based materials (200-710 pC N-1). However, its Curie temperature TC is relatively low (93 °C) limiting its application. In this letter, we found a temperature dependent Raman spectrum in BTZ-0.5BCT nanofibers (NFs), demonstrating a diffused tetragonal-to-cubic phase transition at 300 °C. This means that the TC of the NFs is nearly 207 °C higher than that of the normal bulk material. The increased TC is considered to be associated with the size effect of BTZ-0.5BCT nanoceramic subunits and the nanoporous nature of the fiber, resulting in discontinuous physical properties. The variation of the ferro/piezoelectricity over the fiber surface is attributed to the polycrystalline structure. The d33 (173.32 pm V-1) is improved in terms of the decreased Q factor result in an increase in d33 of 236.54 pm V-1 after polarization. With a high TC and a very large d33, BTZ-0.5BCT NFs are capable of providing electromechanical behavior used in moderate temperatures.

  5. Lead-free 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 nanowires for energy harvesting.

    Science.gov (United States)

    Zhou, Zhi; Bowland, Christopher C; Malakooti, Mohammad H; Tang, Haixiong; Sodano, Henry A

    2016-03-07

    Lead-free piezoelectric nanowires (NWs) show strong potential in sensing and energy harvesting applications due to their flexibility and ability to convert mechanical energy to electric energy. Currently, most lead-free piezoelectric NWs are produced through low yield synthesis methods and result in low electromechanical coupling, which limit their efficiency as energy harvesters. In order to alleviate these issues, a scalable method is developed to synthesize perovskite type 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT) NWs with high piezoelectric coupling coefficient. The piezoelectric coupling coefficient of the BZT-BCT NWs is measured by a refined piezoresponse force microscopy (PFM) testing method and shows the highest reported coupling coefficient for lead-free piezoelectric nanowires of 90 ± 5 pm V(-1). Flexible nanocomposites utilizing dispersed BZT-BCT NWs are fabricated to demonstrate an energy harvesting application with an open circuit voltage of up to 6.25 V and a power density of up to 2.25 μW cm(-3). The high electromechanical coupling coefficient and high power density demonstrated with these lead-free NWs produced via a scalable synthesis method shows the potential for high performance NW-based devices.

  6. Phase transition behaviours near the triple point for Pb-free (1 - x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 piezoceramics

    Science.gov (United States)

    Gao, Jinghui; Dai, Ye; Hu, Xinghao; Ke, Xiaoqin; Zhong, Lisheng; Li, Shengtao; Zhang, Lixue; Wang, Yu; Wang, Dong; Wang, Yan; Liu, Yongbin; Xiao, Hu; Ren, Xiaobing

    2016-08-01

    The reason for the large electromechanical response in Pb-free piezoceramic Ba(Zr0.2Ti0.8)O3-(Ba0.7Ca0.3)TiO3 (BZT-BCT) still remains controversial, and a central issue is whether or not the multi-phase-coexisting point (triple point) in the phase diagram is a thermodynamic tricritical point. In this letter, we study the phase transition behaviour for the ferro-para transitions of BZT-BCT specimens in the vicinity of a triple point. Our results show that latent heat and thermal hysteresis approach zero, while the permittivity peak value is maximized close to the triple-point composition, which suggests that the triple point exhibits nearly tricritical transition behaviours in the BZT-BCT system. Further, the TEM result shows that the domain width is minimized with composition approaching the triple point, which indicates a reduction of the domain wall energy possibly relevant to the tricriticality of the triple point. A sixth-order Landau energy modeling shows that the triple tricritical point provides a free-energy state of near-vanishing polarization anisotropy and thus enhances the piezoelectric response for such a material system.

  7. Ferroelectric substrate effects on the magnetism, magnetotransport, and electroresistance of La0.7Ca0.3MnO3 thin films on BaTiO3

    Science.gov (United States)

    Alberca, A.; Munuera, C.; Tornos, J.; Mompean, F. J.; Biskup, N.; Ruiz, A.; Nemes, N. M.; de Andres, A.; León, C.; Santamaría, J.; García-Hernández, M.

    2012-10-01

    La0.7Ca0.3MnO3 optimally doped epitaxial films were grown on ferroelectric BaTiO3 substrates. Electronic transport (magnetoresistance and electroresistance) and magnetic properties showed important anomalies in the temperature interval between 60 and 150 K, below the metal-insulator transition. Scanning probe microscopy revealed changes in BaTiO3 surface morphology at those temperatures. La0.7Ca0.3MnO3 thickness is a critical factor: 120-Å-thick films showed large anomalies sensitive to electric poling of the BaTiO3, whereas the behavior of 150-Å-thick films is closer to that of the reference La0.7Ca0.3MnO3 samples grown on SrTiO3. We propose that, through inhomogenous strain and electric polarization effects, the ferroelectric substrate induces an inhomogenous spin distribution in the magnetic layer. This would imply the coexistence of in-plane and out-of-plane ferromagnetic patches in La0.7Ca0.3MnO3, possibly interspersed with antiferromagnetic regions, as it has recently been theoretically predicted. Substrate poling effects are investigated, and a magnetoelectric coupling is demonstrated.

  8. Phase separation enhanced magneto-electric coupling in La0.7Ca0.3MnO3/BaTiO3 ultra-thin films

    Science.gov (United States)

    Alberca, A.; Munuera, C.; Azpeitia, J.; Kirby, B.; Nemes, N. M.; Perez-Muñoz, A. M.; Tornos, J.; Mompean, F. J.; Leon, C.; Santamaria, J.; Garcia-Hernandez, M.

    2015-01-01

    We study the origin of the magnetoelectric coupling in manganite films on ferroelectric substrates. We find large magnetoelectric coupling in La0.7Ca0.3MnO3/BaTiO3 ultra-thin films in experiments based on the converse magnetoelectric effect. The magnetization changes by around 30–40% upon applying electric fields on the order of 1 kV/cm to the BaTiO3 substrate, corresponding to magnetoelectric coupling constants on the order of α = (2–5)·10−7 s/m. Magnetic anisotropy is also affected by the electric field induced strain, resulting in a considerable reduction of coercive fields. We compare the magnetoelectric effect in pre-poled and unpoled BaTiO3 substrates. Polarized neutron reflectometry reveals a two-layer behavior with a depressed magnetic layer of around 30 Å at the interface. Magnetic force microscopy (MFM) shows a granular magnetic structure of the La0.7Ca0.3MnO3. The magnetic granularity of the La0.7Ca0.3MnO3 film and the robust magnetoelastic coupling at the La0.7Ca0.3MnO3/BaTiO3 interface are at the origin of the large magnetoelectric coupling, which is enhanced by phase separation in the manganite. PMID:26648002

  9. Synthesis of photocatalytic La(1-x)AxTiO3.5-δ(A=Ba, Sr, Ca) nano perovskites and their application for photocatalytic oxidation of congo red dye in aqueous solution

    Institute of Scientific and Technical Information of China (English)

    M Bradha; T Vijayaraghavan; SP Suriyaraj; R Selvakumar; Anuradha M Ashok

    2015-01-01

    A-site substituted La0.8A0.2TiO3.5–δ(A=Ba, Sr, Ca) nano perovskites were prepared by sol-gel method and characterized using thermogravimetry/differential thermal analysis (TGA/DTA), X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectros-copy and transmission electron microscopy (TEM). XRD analysis showed that the La0.8A0.2TiO3.5–δ(A=Ba, Sr, Ca) nano perovskites derived after calcination at 800 ºC were in single phase with orthorhombic structure. The particle size of all nano perovskites was found to be~20 nm. The synthesized nano perovskites were tested for the photocatalytic decomposition of an azo dye, Congo red. The sequential behavior of La0.8A0.2TiO3.5–δ(A=Ba, Sr, Ca) nanoperovskites for photocatalytic decomposition of congo red in aque-ous solution by visible light at room temperature was studied at various time intervals and the efficiency of degradation of the nanop-erovskites was compared. Among all the A-site substituted La0.8A0.2TiO3.5–δ(A=Ba, Sr, Ca) nano perovskites, Ba substituted com-pound showed the highest dye degradation.

  10. Thermal Hysteresis in La2/3 Ca1/3 MnO3 Films Grown on Tilted SrTiO3 Substrates and Influence of External Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    GUAN Dong-Yi; ZHOU Qing-Li; ZHAO Kun; SUN Jia-Xing; JIN Kui-Juan; CHEN Zheng-Hao; LU Hui-Bin; YANG Guo-Zhen

    2006-01-01

    @@ Thermal hysteresis in the resistivity of La2/3 Ca1/3MnO3 thin films grown on tilted SrTiO3 substrates is simulated by using the random network model on the basis of mixed-phase percolation between metallic and insulating domains.

  11. Proteomic Profiling of Hematopoietic Stem/Progenitor Cells after a Whole Body Exposure of CBA/CaJ Mice to Titanium (48Ti Ions

    Directory of Open Access Journals (Sweden)

    Kanokporn Noy Rithidech

    2015-07-01

    Full Text Available Myeloid leukemia (ML is one of the major health concerns from exposure to radiation. However, the risk assessment for developing ML after exposure to space radiation remains uncertain. To reduce the uncertainty in risk prediction for ML, a much increased understanding of space radiation-induced changes in the target cells, i.e., hematopoietic stem/progenitor cells (HSPCs, is critically important. We used the label-free quantitative mass spectrometry (LFQMS proteomic approach to determine the expression of protein in HSPC-derived myeloid colonies obtained at an early time-point (one week and a late time-point (six months after an acute whole body exposure of CBA/CaJ mice to a total dose of 0, 0.1, 0.25, or 0.5 Gy of heavy-ion titanium (48Ti ions, which are the important component of radiation found in the space environment. Mice exposed to 0 Gy of 48Ti ions served as non-irradiated sham controls. There were five mice per treatment groups at each harvest time. The Trans-Proteomic Pipeline (TPP was used to assign a probability of a particular protein being in the sample. A proof-of-concept based Ingenuity Pathway Analysis (IPA was used to characterize the functions, pathways, and networks of the identified proteins. Alterations of expression levels of proteins detected in samples collected at one week (wk post-irradiation reflects acute effects of exposure to 48Ti ions, while those detected in samples collected at six months (mos post-irradiation represent protein expression profiles involved in the induction of late-occurring damage (normally referred to as genomic instability. Our results obtained by using the IPA analyses indicate a wide array of signaling pathways involved in response to 1 GeV/n 48Ti ions at both harvest times. Our data also demonstrate that the patterns of protein expression profiles are dose and time dependent. The majority of proteins with altered expression levels are involved in cell cycle control, cellular growth and

  12. Effect of nanoporous TiO2 coating and anodized Ca2+ modification of titanium surfaces on early microbial biofilm formation

    Directory of Open Access Journals (Sweden)

    Wennerberg Ann

    2011-03-01

    Full Text Available Abstract Background The soft tissue around dental implants forms a barrier between the oral environment and the peri-implant bone and a crucial factor for long-term success of therapy is development of a good abutment/soft-tissue seal. Sol-gel derived nanoporous TiO2 coatings have been shown to enhance soft-tissue attachment but their effect on adhesion and biofilm formation by oral bacteria is unknown. Methods We have investigated how the properties of surfaces that may be used on abutments: turned titanium, sol-gel nanoporous TiO2 coated surfaces and anodized Ca2+ modified surfaces, affect biofilm formation by two early colonizers of the oral cavity: Streptococcus sanguinis and Actinomyces naeslundii. The bacteria were detected using 16S rRNA fluorescence in situ hybridization together with confocal laser scanning microscopy. Results Interferometry and atomic force microscopy revealed all the surfaces to be smooth (Sa ≤ 0.22 μm. Incubation with a consortium of S. sanguinis and A. naeslundii showed no differences in adhesion between the surfaces over 2 hours. After 14 hours, the level of biofilm growth was low and again, no differences between the surfaces were seen. The presence of saliva increased the biofilm biovolume of S. sanguinis and A. naeslundii ten-fold compared to when saliva was absent and this was due to increased adhesion rather than biofilm growth. Conclusions Nano-topographical modification of smooth titanium surfaces had no effect on adhesion or early biofilm formation by S. sanguinis and A. naeslundii as compared to turned surfaces or those treated with anodic oxidation in the presence of Ca2+. The presence of saliva led to a significantly greater biofilm biovolume but no significant differences were seen between the test surfaces. These data thus suggest that modification with sol-gel derived nanoporous TiO2, which has been shown to improve osseointegration and soft-tissue healing in vivo, does not cause greater biofilm

  13. Enhancing CaP biomimetic growth on TiO2 cuboids nanoparticles via highly reactive facets.

    Science.gov (United States)

    Ruso, Juan M; Verdinelli, Valeria; Hassan, Natalia; Pieroni, Olga; Messina, Paula V

    2013-02-19

    Pure decahedral anatase TiO(2) particles with high content of reactive {001} facets were obtained from titanium(IV) tetrachloride (TiCl(4)) using a microemulsions droplet system at specific conditions as chemical microreactor. The product was systematically characterized by X-ray diffraction, field-emission scanning and transmission electron microscopy (FE-SEM, TEM), N(2) adsorption-desorption isotherms, FT-IR and UV-vis spectroscopy, and photoluminescence studies. The obtained cuboids around 90 nm in size have a uniform and dense surface morphology with a BET specific surface area of 11.91 m(2) g(-1) and a band gap energy (3.18 eV) slightly inferior to the anatase dominated by the less-reactive {101} surface (3.20 eV). The presence of reactive facets on titania anatase favors the biomimetic growth of amorphous tricalcium phosphate after the first day of immersion in simulated human plasma. The results presented here can facilitate and improve the integration of anchored implants and enhance the biological responses to the soft tissues.

  14. Effects of LiF on microwave dielectric properties of 0.25Ca0.8Sr0.2TiO3–0.75Li0.5Nd0.5TiO3 ceramics

    Indian Academy of Sciences (India)

    Fei Liu; Changlai Yuan; Xinyu Liu; Jing Jing Qu

    2015-09-01

    The effects of LiF addition on sinterability, microstructure and microwave dielectric properties of 0.25Ca0.8Sr0.2TiO3–0.75Li0.5Nd0.5TiO3 ceramics were investigated. The LiF addition enhanced the sintering temperature of 0.25Ca0.8Sr0.2TiO3–0.75Li0.5Nd0.5TiO3 ceramics from 1200 to 1300°C, because the LiF addition could compensate the evaporation of Li during the sintering process. It was found that the bulk density and dielectric constant (r) gradually decreased, the quality factor (f) greatly increased and the temperature coefficient of resonant frequency (f) shifted to a near-zero value with the increase in LiF addition. Obviously, excess Li addition could efficiently improve the microwave dielectric properties. In addition, 0.25Ca0.8Sr0.2 TiO3–0.75Li0.5Nd0.5TiO3 + 4.0 wt% LiF ceramics sintered at 1350°C for 4 h exhibited good microwave dielectric properties of r ∼ 123.4, f ∼ 2209 GHz (at 2.43 GHz) and f ∼ 12.3 ppm °C–1.

  15. Synthesis and characterisation of the uranium pyrochlore betafite [(Ca,U){sub 2}(Ti,Nb,Ta){sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    McMaster, Scott A.; Ram, Rahul; Charalambous, Fiona [Centre for Advanced Materials and Industrial Chemistry, School of Applied Sciences RMIT University, GPO Box 2476, Melbourne, Vic 3001 (Australia); Pownceby, Mark I. [CSIRO Process Science and Engineering, Bayview Avenue Clayton, Victoria 3168 (Australia); Tardio, James [Centre for Advanced Materials and Industrial Chemistry, School of Applied Sciences RMIT University, GPO Box 2476, Melbourne, Vic 3001 (Australia); Bhargava, Suresh K., E-mail: suresh.bhargava@rmit.edu.au [Centre for Advanced Materials and Industrial Chemistry, School of Applied Sciences RMIT University, GPO Box 2476, Melbourne, Vic 3001 (Australia)

    2014-09-15

    Highlights: • First published method for preparation of a synthetic form of betafite. • X-ray photoelectron spectroscopy data on uranium oxidation state(s) in synthetic betafite. • Detailed microscopy based characterisation of synthetic betafite. - Abstract: Betafite of composition [(Ca,U){sub 2}(Ti,Nb,Ta){sub 2}O{sub 7}] was prepared via a solid state synthesis route. The synthesis was shown to be sensitive to initial reactant ratios, the atmosphere used (oxidising, neutral, reducing) and time. The optimum conditions for the synthesis of betafite were found to be heating the reactants required at 1150 °C for 48 h under an inert gas atmosphere. XRD characterisation revealed that the synthesised betafite contained minor impurities. EPMA analysis of a sectioned surface showed very small regions of Ca-free betafite on grain boundaries as well as minor rutile impurities. Some heterogeneity between the Nb:Ta ratio was observed by quantitative EPMA but was generally within the nomenclature requirements stated for betafite. SEM analysis revealed the synthesised betafite was comprised mostly of hexaoctohedral crystals of ∼3 μm in diameter. XPS analysis of the sample showed that the uranium in the synthesised betafite was predominately present in the U{sup 5+} oxidation state. A minor amount of U{sup 6+} was also detected which was possibly due to surface oxidation.

  16. Study on the Ca doped BaTiO3 ceramic fibers%钙掺杂钛酸钡陶瓷纤维的研究

    Institute of Scientific and Technical Information of China (English)

    刘伟华; 宋双居; 刘宁

    2011-01-01

    采用溶胶-凝胶法,以醋酸钡、醋酸钙和钛酸丁酯为原料,冰醋酸为催化剂,制备了钙掺杂钛酸钡陶瓷纤维.发现当钙的掺杂量物质的量分数为0.05,0.10,0.15,0.20,0.25时溶胶具有可纺性,掺杂量物质的量分数为0.30,0.35时能形成溶胶,但溶胶不具有可纺性,掺钙量物质的量分数为0.40时不能形成溶胶.应用热分析、X射线粉末衍射、红外和扫描电子显微镜等技术对凝胶和纤维进行了较系统地研究.在1 000℃煅烧60min,升温速率为2℃/min时,得到表面形貌良好的陶瓷纤维.%The Ca doped BaTjO3 ceramic fibers were prepared by sol-gel process with Ba(CH3COO)2, Ca(CH3COO)2 and Ti(OC4 H9 )4 as precursors and CH3COOH as the catalyst. It is found that the sols are spinnable with Ca contents of 0. 05, 0. 10, 0. 15, 0. 20, 0. 25 (a-mount fraction), while not spinnable with 0. 30 and 0. 35 Ca contents, failing to form the sol of 0. 40 Ca contents. A series of researchs were carried out with TGA-DTA, XRD, FT-IR,SEM. Ceramic fibers with perfect surface were obtained under calcined time of 60 minutes held on 1 000 ℃ , at 2 ℃ /minute rate .

  17. Investigating the addition of SiO₂-CaO-ZnO-Na₂O-TiO₂ bioactive glass to hydroxyapatite: Characterization, mechanical properties and bioactivity.

    Science.gov (United States)

    Yatongchai, Chokchai; Placek, Lana M; Curran, Declan J; Towler, Mark R; Wren, Anthony W

    2015-11-01

    Hydroxyapatite (Ca10(PO4)6(OH)2) is widely investigated as an implantable material for hard tissue restoration due to its osteoconductive properties. However, hydroxyapatite in bulk form is limited as its mechanical properties are insufficient for load-bearing orthopedic applications. Attempts have been made to improve the mechanical properties of hydroxyapatite, by incorporating ceramic fillers, but the resultant composite materials require high sintering temperatures to facilitate densification, leading to the decomposition of hydroxyapatite into tricalcium phosphate, tetra-calcium phosphate and CaO phases. One method of improving the properties of hydroxyapatite is to incorporate bioactive glass particles as a second phase. These typically have lower softening points which could possibly facilitate sintering at lower temperatures. In this work, a bioactive glass (SiO2-CaO-ZnO-Na2O-TiO2) is incorporated (10, 20 and 30 wt%) into hydroxyapatite as a reinforcing phase. X-ray diffraction confirmed that no additional phases (other than hydroxyapatite) were formed at a sintering temperature of 560 ℃ with up to 30 wt% glass addition. The addition of the glass phase increased the % crystallinity and the relative density of the composites. The biaxial flexural strength increased to 36 MPa with glass addition, and there was no significant change in hardness as a function of maturation. The pH of the incubation media increased to pH 10 or 11 through glass addition, and ion release profiles determined that Si, Na and P were released from the composites. Calcium phosphate precipitation was encouraged in simulated body fluid with the incorporation of the bioactive glass phase, and cell culture testing in MC-3T3 osteoblasts determined that the composite materials did not significantly reduce cell viability.

  18. Assessment of CaSO{sub 4}:Dy and LiF:Mg,Ti thermoluminescent dosimeters performance in the dosimetry of clinical electron beams; Avaliacao do desempenho dos detectores termoluminesncetes de CaSO{sub 4}:Dy e LiF:Mg,Ti na dosimetria de feixes clinicos de eletrons

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, Maira Goes

    2008-07-01

    The assessment of the performance of CaS0{sub 4}:Dy thermoluminescent detectors produced by IPEN in the dosimetry of clinical electron beams aims to propose an alternative to the LiF:Mg,Ti commercial dosimeters (TLD-100) largely applied in radiation therapy. The two types of thermoluminescent dosimeters were characterised with the use of PMMA, RMI-457 type solid water and water phantoms in radiation fields of 4, 6, 9, 12 and 16 MeV electrons of nominal energies in which the dose-response curves were obtained and the surface and depth doses were determined. The thermoluminescent response dependency with the electron nominal energies and the applied phantom were studied. The CaS0{sub 4}:Dy presented the same behaviour than the LiF:Mg,Ti in such a way that its application as an alternative to the TLD-100 pellets in the radiation therapy dosimetry of electron beams is viable and presents the significantly higher sensitivity to the electron radiation as its main advantage. (author)

  19. Optical spectra of Dy3+-doped GdVO4 and Ca3Sc2Ge3O12 crystals and evaluation of the Ω2/Ω6 ratio as a quality factor for the classification of Dy3+-activated crystalline hosts

    Science.gov (United States)

    Cavalli, Enrico

    2016-11-01

    The room temperature absorption spectra of Dy3+-doped GdVO4 and Ca3Sc2Ge3O12 crystals have been measured and analysed in the framework of the Judd-Ofelt Theory. The calculated intensity parameters have then been correlated with the intensities of the emission bands in the yellow and blue region. The analysis has then been extended to a number of host lattices using literature data, and a general empirical model has been proposed, correlating the Ω2/Ω6 and the yellow to blue (Y/B) ratio in order to define a criterion for predicting the visible luminescence properties of the Dy-activated crystalline materials.

  20. Study of Li{sup +} conduction in Li{sub 1.3}Al{sub 0.3−x}Sc{sub x}Ti{sub 1.7}(PO{sub 4}){sub 3} (x=0.01, 0.03, 0.05 and 0.07) NASICON ceramic compound

    Energy Technology Data Exchange (ETDEWEB)

    Kothari, Dharmesh H.; Kanchan, D.K., E-mail: dkkanchan.ssi@gmail.com

    2016-08-01

    Li{sub 1.3}Al{sub 0.3−x}Sc{sub x}Ti{sub 1.7}(PO{sub 4}){sub 3} (LASTP) (for concentrations x=0.01, 0.03, 0.05 and 0.07) system was prepared using solid state reaction. These ceramic samples were characterized using X-ray diffraction, EDX, SEM, density and DTA–TGA measurements. The electrical properties were studied in the frequency range of 20 MHz to 1 Hz and in the temperature range 303–423 K, using the impedance spectroscopy. The effect of systematic variation of scandium in the LATP lattice has been investigated. The formation of impurity phases has been discussed and found to be detrimental for Li{sup +} conductivity. The non Debye behavior observed in modulus spectra is attributed to local inhomogeneities and impurity phases.

  1. The exohedral Diels-Alder reactivity of the titanium carbide endohedral metallofullerene Ti2C2@D(3h)-C78: comparison with D(3h)-C78 and M3N@D(3h)-C78 (M=Sc and Y) reactivity.

    Science.gov (United States)

    Garcia-Borràs, Marc; Osuna, Sílvia; Luis, Josep M; Swart, Marcel; Solà, Miquel

    2012-06-04

    The chemical functionalization of endohedral (metallo)fullerenes has become a main focus of research in the last few years. It has been found that the reactivity of endohedral (metallo)fullerenes may be quite different from that of the empty fullerenes. Encapsulated species have an enormous influence on the thermodynamics, kinetics, and regiochemistry of the exohedral addition reactions undergone by these species. A detailed understanding of the changes in chemical reactivity due to incarceration of atoms or clusters of atoms is essential to assist the synthesis of new functionalized endohedral fullerenes with specific properties. Herein, we report the study of the Diels-Alder cycloaddition between 1,3-butadiene and all nonequivalent bonds of the Ti(2)C(2)@D(3h)-C(78) metallic carbide endohedral metallofullerene (EMF) at the BP86/TZP//BP86/DZP level of theory. The results obtained are compared with those found by some of us at the same level of theory for the D(3h)-C(78) free cage and the M(3)N@D(3h)-C(78) (M=Sc and Y) metallic nitride EMFs. It is found that the free cage is more reactive than the Ti(2)C(2)@D(3h)-C(78) EMF and this, in turn, has a higher reactivity than M(3)N@D(3h)-C(78). The results indicate that, for Ti(2)C(2)@D(3h)-C(78), the corannulene-type [5,6] bonds c and f, and the type B [6,6] bond 3 are those thermodynamically and kinetically preferred. In contrast, the D(3h)-C(78) free cage has a preference for addition to the [6,6] 1 and 6 bonds and the [5,6] b bond, whereas M(3)N@D(3h)-C(78) favors additions to the [6,6] 6 (M=Sc) and [5,6] d (M=Y) bonds. The reasons for the regioselectivity found in Ti(2)C(2)@D(3h)-C(78) are discussed.

  2. New separation method of no-carrier-added {sup 47}Sc from titanium targets

    Energy Technology Data Exchange (ETDEWEB)

    Bartos, B.; Majkowska, A.; Kasperek, A.; Krajewski, S.; Bilewicz, A. [Institute of Nuclear Chemistry and Technology, Warszawa (Poland). Nuclear Chemistry and Radiochemistry Center

    2012-07-01

    Radionuclides with medium energy beta emission and a several day half-life are attractive candidates for radioimmunotherapy. Among the most promising in this category is {sup 47}Sc produced by fast neutron irradiation (E{sub n} > 1 MeV) of titanium target with high energy neutrons in {sup 47}Ti(n,p){sup 47}Sc nuclear reaction. In the previously reported production scheme the dissolution of the TiO{sub 2} target in hot concentrated H{sub 2}SO{sub 4} and evaporation of the resulting solution were the most time-consuming steps. The present paper describes new, simple and efficient production method of {sup 47}Sc, where the slow dissolution of the target is avoided. After irradiation in fast neutron flux {sup 47}TiO{sub 2} and Li{sub 2}{sup 47}TiF{sub 6} targets were dissolved in HF solutions. Next {sup 47}Sc was separated from the target using anion exchange resin Dowex 1 with 0.4 M HF + 0.06 M HNO{sub 3} solution as eluent. The eluted {sup 47}Sc was adsorbed on cation exchange resin and eluted with 0.5 M of ammonium acetate. The 47Sc separation yield in the proposed procedure is about 90% with the separation time less than 2 h. The obtained no-carrier-added {sup 47}Sc was used to label DOTATATE conjugate with 96% labeling yield. (orig.)

  3. Structural refinement and photoluminescence properties of irregular cube-like (Ca{sub 1-x}Cu{sub x})TiO{sub 3} microcrystals synthesized by the microwave-hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, L.H., E-mail: larissahelena2009@gmail.com [DQ-UFSCar-Universidade Federal de Sao Carlos, P.O. Box 676, 13565-905 Sao Carlos, SP (Brazil); Moura, A.P. de; Mazzo, T.M. [UNESP-Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, SP (Brazil); Ramirez, M.A. [UNESP-Universidade Estadual Paulista, 12516-410 Guaratingueta, SP (Brazil); Cavalcante, L.S.; Antonio, S.G.; Avansi, W. [UNESP-Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, SP (Brazil); Mastelaro, V.R. [IFSC-USP, AV. Trabalhador Sao Carlense 400, 13560-970 Sao Carlos, SP (Brazil); Longo, E. [DQ-UFSCar-Universidade Federal de Sao Carlos, P.O. Box 676, 13565-905 Sao Carlos, SP (Brazil); UNESP-Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, SP (Brazil); Varela, J.A. [UNESP-Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, SP (Brazil)

    2012-09-14

    In this paper, calcium copper titanate (Ca{sub 1-x}Cu{sub x})TiO{sub 3} microcrystals with (x = 0, 0.01 and 0.02) were synthesized by the microwave-hydrothermal method at 140 Degree-Sign C for 30 min. These crystals were analyzed by X-ray diffraction (XRD), Rietveld refinement, X-ray absorption near-edge structure spectroscopy (XANES), micro-Raman spectroscopy, field emission scanning electron microscopy (FE-SEM). Its optical properties were investigated by ultraviolet-visible (UV-vis) absorption and photoluminescence (PL) measurements. XRD patterns, Rietveld refinement and micro-Raman spectroscopy indicated that these crystals present a perovskite-type orthorhombic structure. The Rietveld refinement data, micro-Raman and XANES spectra suggested that the substitution of Ca by Cu in A-site promoted a displacement of Ti atoms to off-center symmetric, which leads distortions on the cuboctahedral [CaO{sub 12}] clusters neighboring and consequently promotes a strain into the CaTiO{sub 3} lattice. FE-SEM images showed that these cube-like microcrystals have an irregular shape due to Ostwald-ripening and self-assembly of plates and cubes in growth process. The defects and distortions into lattice at medium- and short-range on the [CaO{sub 12}]/[TiO{sub 6}] clusters promotes the structural order-disorder responsible by the intense PL properties of these microcrystals. The microcrystals are promising candidates for future applications in optical devices. Highlights: Black-Right-Pointing-Pointer Any secondary phases were detected in the (Ca{sub 1-x}Cu{sub x})TiO{sub 3} powders. Black-Right-Pointing-Pointer Cu atoms are able to induce a local polarization in [CaO{sub 12}] and [TiO{sub 6}] clusters. Black-Right-Pointing-Pointer Ostwald-ripening and self-assembly are dominant mechanisms of these microcrystals. Black-Right-Pointing-Pointer PL emission presents a shift to green region as the concentration of Cu increases.

  4. Nuclear Level Density and Gamma-Ray Strength Function of 43Sc

    CERN Document Server

    Bürger, A; Hilaire, S; Guttormsen, M; Harissopulos, S; Kmiecik, M; Konstantinopoulos, T; Krticka, M; Lagoyannis, A; Lönnroth, T; Mazurek, K; Norrby, M; Nyhus, H T; Perdikakis, G; Siem, S; Spyrou, A; Syed, N U H; 10.1103/PhysRevC.85.064328

    2012-01-01

    The nuclear level density and the gamma-ray strength function have been determined for 43Sc in the energy range up to 2 MeV below the neutron separation energy using the Oslo method with the 46Ti(p,alpha)43Sc reaction. A comparison to 45Sc shows that the level density of 43Sc is smaller by an approximately constant factor of two. This behaviour is well reproduced in a microscopical/combinatorial model calculation. The gamma-ray strength function is showing an increase at low gamma-ray energies, a feature which has been observed in several nuclei but which still awaits theoretical explanation.

  5. Ultrasensitive photoelectrochemical immunoassay for CA19-9 detection based on CdSe@ZnS quantum dots sensitized TiO2NWs/Au hybrid structure amplified by quenching effect of Ab2@V(2+) conjugates.

    Science.gov (United States)

    Zhu, Hua; Fan, Gao-Chao; Abdel-Halim, E S; Zhang, Jian-Rong; Zhu, Jun-Jie

    2016-03-15

    A novel, enhanced photoelectrochemical immunoassay was established for sensitive and specific detection of carbohydrate antigen 19-9 (CA19-9, Ag). In this protocol, TiO2 nanowires (TiO2NWs) were first decorated with Au nanoparticles to form TiO2NWs/Au hybrid structure, and then coated with CdSe@ZnS quantum dots (QDs) via the layer-by-layer method, producing TiO2NWs/Au/CdSe@ZnS sensitized structure, which was employed as the photoelectrochemical matrix to immobilize capture CA19-9 antibodies (Ab1); whereas, bipyridinium (V(2+)) molecules were labeled on signal CA19-9 antibodies (Ab2) to form Ab2@V(2+) conjugates, which were used as signal amplification elements. The TiO2NWs/Au/CdSe@ZnS sensitized structure could adequately absorb light energy and dramatically depress electron-hole recombination, resulting in evidently enhanced photocurrent intensity of the immunosensing electrode. While target Ag were detected, the Ab2@V(2+) conjugates could significantly decrease the photocurrent detection signal because of strong electron-withdrawing property of V(2+) coupled with evident steric hindrance of Ab2. Thanks to synergy effect of TiO2NWs/Au/CdSe@ZnS sensitized structure and quenching effect of Ab2@V(2+) conjugates, the well-established photoelectrochemical immunoassay exhibited a low detection limit of 0.0039 U/mL with a wide linear range from 0.01 U/mL to 200 U/mL for target Ag detection. This proposed photoelectrochemical protocol also showed good reproducibility, specificity and stability, and might be applied to detect other important biomarkers.

  6. Effect of Ca2+ substitution on impedance and electrical conduction mechanism of Ba1-xCaxZr0.1Ti0.9O3 (0.00≤x≤0.20) ceramics

    Science.gov (United States)

    Mondal, Tanusree; Das, Sayantani; Badapanda, T.; Sinha, T. P.; Sarun, P. M.

    2017-03-01

    The Ca modified Ba1-xCaxZr0.1Ti0.9O3 (BCZT) system for x=0.00-0.20 is synthesized by the high-temperature conventional solid state reaction method. The morphotropic phase boundary (MPB) between the tetragonal and cubic structure is obtained at room temperature for the composition x=0.15. The doping of Ca facilitates the enhancement of the homogeneity of microstructure and growth of the grain size. The phase transition is also confirmed by Raman spectroscopy. In order to explore the effect of Ca concentration variation on the conduction mechanism of BaZr0.1Ti0.9O3 (BZT) ceramic, the frequency dependent ac impedance spectroscopy technique is used at various temperatures. The effect of Ca doping on the electrical properties of BZT is clearly noticeable. The resistance of the grain (bulk) and the grain boundary is increased as a consequence of the increase in the activation energy of Ca substituted BZT samples. The enhanced resistivity of the Ca substituted BZT ceramics is explained in terms of the decrease in the mobility of the charge carriers associated with the lattice distortion. The electric modulus analysis reveals the enhanced capacitance of BCZT ceramics which is in good agreement with the results obtained from complex impedance analysis.

  7. Cubic-tetragonal phase transition in Ca{sub 0.04}Sr{sub 0.96}TiO{sub 3}: a combined specific heat and neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Gallardo, M C [Departamento de Fisica de la Materia Condensada, Instituto de Ciencia de Materiales de Sevilla, Universidad de Sevilla-CSIC, PO Box 1065, 41080 Sevilla (Spain); Becerro, A I [Departamento de Quimica Inorganica, Instituto de Ciencia de Materiales de Sevilla, Universidad de Sevilla-CSIC, Avenida Americo Vespucio s/n, 41092 Sevilla (Spain); Romero, F J [Departamento de Fisica de la Materia Condensada, Instituto de Ciencia de Materiales de Sevilla, Universidad de Sevilla-CSIC, PO Box 1065, 41080 Sevilla (Spain); Cerro, J del [Departamento de Fisica de la Materia Condensada, Instituto de Ciencia de Materiales de Sevilla, Universidad de Sevilla-CSIC, PO Box 1065, 41080 Sevilla (Spain); Seifert, F [Bayerisches Geoinstitut, Universitaet Bayreuth, 95440-Bayreuth (Germany); Redfern, S A T [Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge (United Kingdom)

    2003-01-22

    The specific heat corresponding to the tetragonal-to-cubic transition in Ca{sub 0.04}Sr{sub 0.96}TiO{sub 3} perovskite has been measured by conduction calorimetry. The order parameter of the transition has been obtained by means of neutron diffraction at low temperatures. Comparison of calorimetric data with the evolution of the order parameter indicates that this transition seems to follow a mean field Landau potential as in SrTiO{sub 3}. The linear behaviour of the excess of entropy versus temperature suggests that a 2-4 Landau potential is sufficient to describe the transition.

  8. Investigation on microwave dielectric properties and microstructures of (1−x) LaAlO{sub 3}-xCa{sub 0.2}Sr{sub 0.8}TiO{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Liangzhu, E-mail: huixinglin@mail.sic.ac.cn [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Lin, Huixing; Zhao, XiangYu; Yao, Xiaogang; Jiang, Shaohu; He, Fei; Li, Botao; Luo, Lan [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China)

    2015-11-15

    The structural, microstructural and microwave dielectric properties of (1−x) LaAlO{sub 3}-xCa{sub 0.2}Sr{sub 0.8}TiO{sub 3} ceramics prepared by the conventional solid state ceramic route have been investigated. The formation of solid solutions (1−x) LaAlO{sub 3}-xCa{sub 0.2}Sr{sub 0.8}TiO{sub 3} was confirmed by the X-ray diffraction patterns and the EDS analysis. The lattice parameter, average grain size and dielectric constant (ε{sub r}) increase with increasing amount of Ca{sub 0.2}Sr{sub 0.8}TiO{sub 3} whereas the quality factor (Q × f) decreases. The increasing temperature coefficient of resonant frequency (τ{sub f}) caused by the decreasing tolerance factor with x ranging from 0.3 to 0.7. The τ{sub f} can be tuned near zero at x = 0.5. Specimen with the composition of 0.5LaAlO{sub 3}–0.5Ca{sub 0.2}Sr{sub 0.8}TiO{sub 3} possesses an excellent combination of microwave dielectric properties: ε{sub r} ∼ 32.7, Q × f ∼ 33400 GHz, τ{sub f} ∼ −2.5 ppm/°C. - Highlights: • A novel (1−x) LaAlO{sub 3}-xCa{sub 0.2}Sr{sub 0.8}TiO{sub 3} microwave ceramics were investigated. • The ceramics formed a solid solution confirmed by XRD and EDS. • When x increases, the ceramics Q × f·τ{sub f} decrease, while ε{sub r} increased nonlinearly. • 0.5LaAlO{sub 3}–0.5Ca{sub 0.2}Sr{sub 0.8}TiO{sub 3}ε{sub r} ∼ 32.7, Q × f ∼ 33400 GHz, τ{sub f} ∼ −2.5 ppm/°C.

  9. PDMS-SiO{sub 2}-TiO{sub 2}-CaO hybrid materials – Cytocompatibility and nanoscale surface features

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, J. Carlos [CICECO - Aveiro Institute of Materials, Department of Materials and Ceramic Engineering, University of Aveiro, 3810-193 Aveiro (Portugal); Wacha, András [Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok körútja 2, Budapest 1117 (Hungary); Gomes, Pedro S.; Fernandes, M. Helena R. [Laboratory for Bone Metabolism and Regeneration, Faculdade de Medicina Dentária, Universidade do Porto (Portugal); Fernandes, M. Helena Vaz [CICECO - Aveiro Institute of Materials, Department of Materials and Ceramic Engineering, University of Aveiro, 3810-193 Aveiro (Portugal); Salvado, Isabel M. Miranda, E-mail: isabelmsalvado@ua.pt [CICECO - Aveiro Institute of Materials, Department of Materials and Ceramic Engineering, University of Aveiro, 3810-193 Aveiro (Portugal)

    2016-07-01

    Two PDMS-SiO{sub 2}-TiO{sub 2}-CaO porous hybrid materials were prepared using the same base composition, precursors, and solvents, but following two different sol-gel procedures, based on the authors' previous works where for the first time, in this hybrid system, calcium acetate was used as calcium source. The two different procedures resulted in monolithic materials with different structures, microstructures, and surface wettability. Even though both are highly hydrophobic (contact angles of 127.2° and 150.6°), and present different filling regimes due to different surface topographies, they have demonstrated to be cytocompatible when tested with human osteoblastic cells, against the accepted idea that high-hydrophobic surfaces are not suitable to cell adhesion and proliferation. At the nanoscale, the existence of hydrophilic silica domains containing calcium, where water molecules are physisorbed, is assumed to support this capability, as discussed. - Highlights: • Two hybrid materials were prepared following two different sol-gel procedures. • Both are highly hydrophobic but demonstrated to be cytocompatible. • Different filling regimes were observed.

  10. Synthesis and Characterizations of Novel Ca-Mg-Ti-Fe-Oxides Based Ceramic Nanocrystals and Flexible Film of Polydimethylsiloxane Composite with Improved Mechanical and Dielectric Properties for Sensors

    Directory of Open Access Journals (Sweden)

    Ashis Tripathy

    2016-02-01

    Full Text Available Armalcolite, a rare ceramic mineral and normally found in the lunar earth, was synthesized by solid-state step-sintering. The in situ phase-changed novel ceramic nanocrystals of Ca-Mg-Ti-Fe based oxide (CMTFOx, their chemical reactions and bonding with polydimethylsiloxane (PDMS were determined by X-ray diffraction, infrared spectroscopy, and microscopy. Water absorption of all the CMTFOx was high. The lower dielectric loss tangent value (0.155 at 1 MHz was obtained for the ceramic sintered at 1050 °C (S1050 and it became lowest for the S1050/PDMS nanocomposite (0.002 at 1 MHz film, which was made by spin coating at 3000 rpm. The excellent flexibility (static modulus ≈ 0.27 MPa and elongation > 90%, viscoelastic property (tanδ = E″/E′: 0.225 and glass transition temperature (Tg: −58.5 °C were obtained for S1050/PDMS film. Parallel-plate capacitive and flexible resistive humidity sensors have been developed successfully. The best sensing performance of the present S1050 (3000% and its flexible S1050/PDMS composite film (306% based humidity sensors was found to be at 100 Hz, better than conventional materials.

  11. Novel magnetic–dielectric composite ceramic obtained from Y{sub 3}Fe{sub 5}O{sub 12} and CaTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Paiva, D.V.M. [Grupo de Química de Materiais Avançados (GQMAT), Departamento de Química Analítica e Físico-Química, Universidade Federal do Ceará – UFC, Campus do Pici, CP 12100, CEP 60451-970 Fortaleza, CE (Brazil); Silva, M.A.S. [Laboratório de Telecomunicações e Ciência e Engenharia de Materiais (LOCEM), Departamento de Física, Universidade Federal do Ceará (Brazil); Ribeiro, T.S.; Vasconcelos, I.F. [Laboratório de Magnetismo e Materiais Magnéticos, Departamento de Engenharia Metalúrgica e de Materiais, UFC (Brazil); Sombra, A.S.B.; Góes, J.C. [Laboratório de Telecomunicações e Ciência e Engenharia de Materiais (LOCEM), Departamento de Física, Universidade Federal do Ceará (Brazil); Fechine, P.B.A., E-mail: fechine@ufc.br [Grupo de Química de Materiais Avançados (GQMAT), Departamento de Química Analítica e Físico-Química, Universidade Federal do Ceará – UFC, Campus do Pici, CP 12100, CEP 60451-970 Fortaleza, CE (Brazil)

    2015-09-25

    Highlights: • The density of composites was improved with addition of CTO. • Dielectric permittivity of the composites presented values above the expected. • The composites presented magnetic permeability higher than YIG after 500 MHz. - Abstract: This work investigates the microstructure and magnetic–dielectric properties of the CaTiO{sub 3} (CTO) and Y{sub 3}Fe{sub 5}O{sub 12} (YIG) composite ceramic. CTO is a paramagnetic ceramic, presents a positive value of Resonant Frequency Temperature Coefficients (τ{sub f}) and has high dielectric permittivity (ε{sub r}) while YIG is ferromagnetic, has low ε{sub r} and negative τ{sub f} values. Therefore, it is expected that the composite from these individual phase shows new properties, or a mix of them derived from each component. X-ray powder diffraction (XRPD), Scanning Electron Microscope (SEM), Raman and {sup 57}Fe Mössbauer spectroscopy were performed to confirm the phases of the composites. The dielectric and magnetic properties in Radio-Microwave frequencies were studied by impedance spectroscopy using different geometries. It was observed a densification improvement resulting from the insertion of the CTO in composites and a chemical reaction between YIG and CTO phases. This new composite has potential applications in bulk and thick/thin films devices.

  12. Microstructural and Dielectric Properties of Zr Doped Microwave Sintered CaCu3Ti4O12 Synthesized by Sol-Gel Route

    Directory of Open Access Journals (Sweden)

    S. Jesurani

    2014-01-01

    Full Text Available Polycrystalline samples with the chemical formula CaCu3Ti4-xZrxO12 (x=0, 0.02, 0.1, 0.2, 0.5, and 0.1 CCTZO were synthesized from metal nitrate solutions by the sol-gel method, followed by conventional and microwave heat treatments. The X-ray diffraction pattern of powder calcined at 800°C in conventional furnace for 3 h showed formation of a single phase. The crystal structure did not change on doping with zirconium and it remained cubic in the five studied compositions. The surface morphology of samples sintered at 1000°C in microwave furnace for 10 min was observed using a high resolution scanning electron microscope (HR-SEM. The grain sizes were in the range of 250 nm–5 μm for these samples. HRSEM results show that doping with Zr enhanced grain growth or densification. Energy dispersive X-ray spectroscopy (EDX confirmed the presence of Zr. The dielectric characteristics of Zr doped CCTO were studied with an LCR meter in the frequency range of 50 Hz–1 MHz. A very high dielectric constant 21,500 was observed for the sample doped with Zr (0.02 mol% at 50 Hz.

  13. Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption

    Directory of Open Access Journals (Sweden)

    Ashis Tripathy

    2016-07-01

    Full Text Available Despite the many attractive potential uses of ceramic materials as humidity sensors, some unavoidable drawbacks, including toxicity, poor biocompatibility, long response and recovery times, low sensitivity and high hysteresis have stymied the use of these materials in advanced applications. Therefore, in present investigation, we developed a capacitive humidity sensor using lead-free Ca,Mg,Fe,Ti-Oxide (CMFTO-based electro-ceramics with perovskite structures synthesized by solid-state step-sintering. This technique helps maintain the submicron size porous morphology of the developed lead-free CMFTO electro-ceramics while providing enhanced water physisorption behaviour. In comparison with conventional capacitive humidity sensors, the presented CMFTO-based humidity sensor shows a high sensitivity of up to 3000% compared to other materials, even at lower signal frequency. The best also shows a rapid response (14.5 s and recovery (34.27 s, and very low hysteresis (3.2% in a 33%–95% relative humidity range which are much lower values than those of existing conventional sensors. Therefore, CMFTO nano-electro-ceramics appear to be very promising materials for fabricating high-performance capacitive humidity sensors.

  14. Characterization of Ordering in A-Site Deficient Perovskite Ca1-xLa2x/3TiO3 Using STEM/EELS.

    Science.gov (United States)

    Danaie, Mohsen; Kepaptsoglou, Demie; Ramasse, Quentin M; Ophus, Colin; Whittle, Karl R; Lawson, Sebastian M; Pedrazzini, Stella; Young, Neil P; Bagot, Paul A J; Edmondson, Philip D

    2016-10-03

    The vacancy ordering behavior of an A-site deficient perovskite system, Ca1-xLa2x/3TiO3, was studied using atomic resolution scanning transmission electron microscopy (STEM) in conjunction with electron energy-loss spectroscopy (EELS), with the aim of determining the role of A-site composition changes. At low La content (x = 0.2), adopting Pbnm symmetry, there was no indication of long-range ordering. Domains, with clear boundaries, were observed in bright-field (BF) imaging, but were not immediately visible in the corresponding high-angle annular dark-field (HAADF) image. These boundaries, with the aid of displacement maps from A-site cations in the HAADF signal, are shown to be tilt boundaries. At the La-rich end of the composition (x = 0.9), adopting Cmmm symmetry, long-range ordering of vacancies and La(3+) ions was observed, with alternating La-rich and La-poor layers on (001)p planes, creating a double perovskite lattice along the c axis. These highly ordered domains can be found isolated within a random distribution of vacancies/La(3+), or within a large population, encompassing a large volume. In regions with a high number density of double perovskite domains, these highly ordered domains were separated by twin boundaries, with 90° or 180° lattice rotations across boundaries. The occurrence and characteristics of these ordered structures are discussed and compared with similar perovskite systems.

  15. Magnetic properties of SrTiO{sub 3}/Pr{sub 2/3}Ca{sub 1/3}MnO{sub 3} multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Niebieskikwiat, D; Guitarra, S R [Colegio de Ciencias e Ingenieria, Universidad San Francisco de Quito, Quito (Ecuador); Haberkorn, N F; Guimpel, J, E-mail: niebied@usfq.edu.e [Instituto Balseiro - Centro Atomico Bariloche, 8400 Bariloche (Argentina)

    2010-01-01

    Nanoscale ferromagnetic (FM) clusters embedded within insulating (I) layers of the antiferromagnetic Pr{sub 2/3}Ca{sub 1/3}MnO{sub 3} (PCMO) are known to improve the magnetoresistance ratio of FM-I magnetoresistive multilayers. Here, we study the magnetic properties of perovskite superlattices comprised of five PCMO layers of variable thickness t separated by 5nm-thick spacers of SrTiO{sub 3} (STO). Several multilayers (1.5 nm {<=} t {<=} 8 nm) were grown on (001) STO substrates by magnetron sputtering. We show that the magnetic moment of PCMO due to the FM inclusions presents a maximum for t {approx} 3 nm, accompanied by an abrupt increase of coercivity and exchange bias field. The nonmagnetic nature of the neighboring STO layers demonstrates that the observed behavior is not related to any interlayer exchange coupling, but the geometrical matching between layer thickness and FM domain size is the key driver for the enhancement of the FM moment and anisotropy energy. These results open a new door for the optimization of perovskite based spintronic devices.

  16. Structural analysis, optical and dielectric function of [Ba0.9Ca0.1](Ti0.9Zr0.1)O3 nanocrystals

    Science.gov (United States)

    Herrera-Pérez, G.; Morales, D.; Paraguay-Delgado, F.; Borja-Urby, R.; Reyes-Rojas, A.; Fuentes-Cobas, L. E.

    2016-09-01

    This work presents the identification of inter-band transitions in the imaginary part of the dielectric function (ɛ2) derived from the Kramers-Kronig analysis for [Ba0.9Ca0.1](Ti0.9Zr0.1)O3 (BCZT) nanocrystals synthesized by the modified Pechini method. The analysis started with the chemical identification of the atoms that conform BCZT in the valence loss energy region of a high energy-resolution of electron energy loss spectroscopy. The indirect band energy (Eg) was determined in the dielectric response function. This result is in agreement with the UV-Vis technique, and it obtained an optical band gap of 3.16 eV. The surface and volume plasmon peaks were observed at 13.1 eV and 26.2 eV, respectively. The X-ray diffraction pattern and the Rietveld refinement data of powders heat treated at 700 °C for 1 h suggest a tetragonal structure with a space group (P4 mm) with the average crystal size of 35 nm. The average particle size was determined by transmission electron microscopy.

  17. Design and Development for Capacitive Humidity Sensor Applications of Lead-Free Ca,Mg,Fe,Ti-Oxides-Based Electro-Ceramics with Improved Sensing Properties via Physisorption

    Science.gov (United States)

    Tripathy, Ashis; Pramanik, Sumit; Manna, Ayan; Bhuyan, Satyanarayan; Azrin Shah, Nabila Farhana; Radzi, Zamri; Abu Osman, Noor Azuan

    2016-01-01

    Despite the many attractive potential uses of ceramic materials as humidity sensors, some unavoidable drawbacks, including toxicity, poor biocompatibility, long response and recovery times, low sensitivity and high hysteresis have stymied the use of these materials in advanced applications. Therefore, in present investigation, we developed a capacitive humidity sensor using lead-free Ca,Mg,Fe,Ti-Oxide (CMFTO)-based electro-ceramics with perovskite structures synthesized by solid-state step-sintering. This technique helps maintain the submicron size porous morphology of the developed lead-free CMFTO electro-ceramics while providing enhanced water physisorption behaviour. In comparison with conventional capacitive humidity sensors, the presented CMFTO-based humidity sensor shows a high sensitivity of up to 3000% compared to other materials, even at lower signal frequency. The best also shows a rapid response (14.5 s) and recovery (34.27 s), and very low hysteresis (3.2%) in a 33%–95% relative humidity range which are much lower values than those of existing conventional sensors. Therefore, CMFTO nano-electro-ceramics appear to be very promising materials for fabricating high-performance capacitive humidity sensors. PMID:27455263

  18. Synthesis and Characterizations of Novel Ca-Mg-Ti-Fe-Oxides Based Ceramic Nanocrystals and Flexible Film of Polydimethylsiloxane Composite with Improved Mechanical and Dielectric Properties for Sensors

    Science.gov (United States)

    Tripathy, Ashis; Pramanik, Sumit; Manna, Ayan; Azrin Shah, Nabila Farhana; Shasmin, Hanie Nadia; Radzi, Zamri; Abu Osman, Noor Azuan

    2016-01-01

    Armalcolite, a rare ceramic mineral and normally found in the lunar earth, was synthesized by solid-state step-sintering. The in situ phase-changed novel ceramic nanocrystals of Ca-Mg-Ti-Fe based oxide (CMTFOx), their chemical reactions and bonding with polydimethylsiloxane (PDMS) were determined by X-ray diffraction, infrared spectroscopy, and microscopy. Water absorption of all the CMTFOx was high. The lower dielectric loss tangent value (0.155 at 1 MHz) was obtained for the ceramic sintered at 1050 °C (S1050) and it became lowest for the S1050/PDMS nanocomposite (0.002 at 1 MHz) film, which was made by spin coating at 3000 rpm. The excellent flexibility (static modulus ≈ 0.27 MPa and elongation > 90%), viscoelastic property (tanδ = E″/E′: 0.225) and glass transition temperature (Tg: −58.5 °C) were obtained for S1050/PDMS film. Parallel-plate capacitive and flexible resistive humidity sensors have been developed successfully. The best sensing performance of the present S1050 (3000%) and its flexible S1050/PDMS composite film (306%) based humidity sensors was found to be at 100 Hz, better than conventional materials. PMID:26927116

  19. Effects of Cr2O3 doping on the microstructure and electrical properties of (Ba,Ca)(Zr,Ti)O3 lead-free ceramics

    Science.gov (United States)

    Xia, Xiang; Jiang, Xiangping; Chen, Chao; Jiang, Xingan; Tu, Na; Chen, Yunjing

    2016-06-01

    Lead-free ceramics (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3- x wt.%Cr2O3 (BCZT- xCr) were prepared via the conventional solid-state reaction method. The microstructure and electrical properties of BCZT- xCr samples were systematically studied. XRD and Raman results showed that all samples possessed a single phased perovskite structure and were close to the morphotropic phase boundary (MPB). With the increase of the Cr content, the rhombohedral-tetragonal phase transition temperature ( T R-T) increases slightly, and the Curie temperature ( T C) shifts towards the low temperature side. XPS analysis reveals that Cr3+ and Cr5 + ions co-existed in Cr-doped BCZT ceramics, indicating the different impact on the electrical properties from Cr ions as "acceptor" or "donor". For the x = 0.1 sample, relative high piezoelectric constants d 33 (˜316 pC/N) as well as high Q m (˜554) and low tanδ (˜0.8%) were obtained. In addition, the AC conductivity was also investigated. Hopping charge was considered as the main conduction mechanism at low temperature. As the temperature increases, small polarons and oxygen vacancies conduction played important roles.

  20. Multiferroic behavior on nanometric La2/3Ca1/3MnO3 / BaTiO3 bilayers

    Science.gov (United States)

    Prieto, Pedro; Ordoñez, John Edward; Gomez, Maria Elena; Lopera, Wilson

    2014-03-01

    We have deposited bilayers of the FM La2/3Ca1/3MnO3 and FE BaTiO3 as a route to design systems with artificial magnetoelectric coupling on LCMO/BTO/Nb:STO system. We maintain a fixed magnetic layer thickness (tLCMO = 48 nm) and varying the thickness of the ferroelectric layer (tBTO = 20, 50, 100 nm). We analyze the influence of the thickness ratio (tBTO/ tLCMO) in electrical and magnetic properties of manganite. From X-ray diffraction analysis we observed that the samples grew textured. Magnetization and transport measurements indicate a possible multiferroic behavior in the bilayer. We found an increase in the Curie and metal-insulator transition temperature in the bilayer in comparison with those for LCMO (48nm)/STO. Hysteresis loops on bilayers show ferromagnetic behavior. This work has been supported by the ``El Patrimonio Autónomo Fondo Nacional de Financiamiento para CT&I FJC'' Colciencias-CENM Research Projects: No. 1106-48-925531 and CI7917-CC 10510 contract 0002-2013 COLCIENCIAS-UNIVALLE.

  1. Increased fluorescence intensity in CaTiO3:Pr3+ phosphor due to NH3 treatment and Nb Co-doping

    Science.gov (United States)

    Holliday, K. S.; Kohlgruber, T. A.; Tran, I. C.; Åberg, D.; Seeley, Z. M.; Bagge-Hansen, M.; Srivastava, A. M.; Cherepy, N. J.; Payne, S. A.

    2016-10-01

    Development of next generation red phosphors for commercial lighting requires understanding of how increased luminescence is achieved by various treatment strategies. In this work, we compare co-doping with Nb to NH3 treatment of CaTiO3:Pr phosphors to reveal a general mechanism responsible for the increased luminescence. The phosphors were synthesized using standard solid-state synthesis techniques and the fluorescence was characterized for potential use in fluorescent lighting, with 254 nm excitation. The lifetime of the fluorescence was determined and used to identify a change in a trap state by the co-doping of Nb5+ in the phosphor. The oxidation state of the Pr was probed by NEXAFS and revealed that both Nb5+ co-doping and NH3 treatment reduced the number of non-fluorescing Pr4+ centers. Calculations were performed to determine the energetically favorable defects. Vacuum annealing was also used to further probe the nature of the trap state. It was determined that NH3 treatments reduce the number of Pr4+ non-fluorescing centers, while Nb5+ co-doping additionally reduces the number of excess oxygen trap states that quench the fluorescence.

  2. Structure, tribocorrosion and biocide characterization of Ca, P and I containing TiO2 coatings developed by plasma electrolytic oxidation

    Science.gov (United States)

    de Viteri, V. Sáenz; Bayón, R.; Igartua, A.; Barandika, G.; Moreno, J. Esteban; Peremarch, C. Pérez-Jorge; Pérez, M. Martínez

    2016-03-01

    In hip joint implants, in particular in the stems, wear-corrosion effects can accelerate the degradation of the biomaterial. The lack of osseointegration and the risk of contracting implant-associated infections may be other reasons for a premature failure of the implant. In this work, TiO2 coatings have been developed by means of plasma electrolytic oxidation (PEO) technique in order to achieve wear-resistant hard coatings with osseointegration ability and biocide characteristics. During the PEO process, elements that favor cell growth, like Ca and P, were introduced into the coating. With the purpose of providing the coating with antibacterial properties iodine was added like biocide agent. The microstructure and chemical composition of the developed coatings were analyzed in order to see if the surface of the films was suitable for the cell attachment. The effect of wear-corrosion synergy was studied by means of tribocorrosion tests. Finally, the biocide capacity of iodine against Staphylococcus aureus and Staphylococcus epidermidis was analyzed through bacterial adhesion tests. High wear and corrosion resistance was shown in one of the developed coatings. The achieved surface microstructures seem to be appropriate to improve the osseointegration with proper pore size and porosity index. The antibacterial capacity of iodine was confirmed for S. epidermidis.

  3. Fabrication of TiO2-strontium loaded CaSiO3/biopolymer coatings with enhanced biocompatibility and corrosion resistance by controlled release of minerals for improved orthopedic applications.

    Science.gov (United States)

    Raj, V; Raj, R Mohan; Sasireka, A; Priya, P

    2016-07-01

    Titanium dioxide (TiO2) arrays were fabricated on Ti alloy by anodization method. Synthesis of CaSiO3 (CS) and various concentrations (1X-5X) of Sr(2+) substitutions in CS coatings on TiO2 substrate was achieved through an electrophoretic deposition technique. Fast release of mineral ions from implant surface produce over dosage effect and it is a potential hazardous factor for osteoblasts. So, in order to prevent the fast release of minerals, biopolymer coating was applied above the composite coatings. The coatings were characterized by FTIR, XRD, FE-SEM and EDX techniques. The mechanical, anticorrosion, antimicrobial properties and biocompatibility of the coatings were evaluated. Studies on the mechanical properties indicate that the addition of Sr(2+) and biopolymer increase the hardness strength of the coatings. The metal ion release from the coatings was studied by ICP-AES. The electrochemical properties of the coatings were studied in Ringer's solution, in which CS-3X/Chi-PVP coating on TiO2 exhibits good anticorrosion property and high resistivity against Escherichia coli and Staphylococcus aureus compared to CS-3X coating on TiO2. In vitro cell experiments indicate that osteoblasts show good adhesion and high growth rates for CS-3X/Chi-PVP coated TiO2 substrate, indicating that the surface cytocompatibility of CS-3X/Chi-PVP coated TiO2 substrate is significantly improved by the controlled release of mineral ions. In conclusion, the surface modification of TiO2/CS-3X/Chi-PVP coated titanium is a potential candidate for implant coating.

  4. 45Ti extraction using hydroxamate resin

    DEFF Research Database (Denmark)

    Gagnon, K.; Severin, Gregory; Barnhart, T. E.

    2012-01-01

    As an attractive radionuclide for positron emission tomography, this study explores the extraction and reactivity of 45Ti produced via the 45Sc(p,n)45Ti reaction on a GE PETtrace. Using a small hydroxamate column, we have demonstrated an overall recovery of >50% of 45Ti in ~1 mL of 1M oxalic acid...

  5. Crystalline orientations of Tl2Ba2Ca2Cu3O(x) grains on MgO, SrTiO3, and LaAlO3 substrates

    Science.gov (United States)

    Liou, S. H.; Wu, C. Y.

    1992-01-01

    Crystalline orientations of Tl2Ba2Ca2Cu3O(x) grains in magnetron sputtered films on MgO (001), SrTiO3 (001), and LaAlO3 (001) substrates were investigated by scanning electron microscopy. In contrast to the nearly single crystalline films on the lattice matched substrates SrTiO3 and LaAlO3, films on the MgO (001) substrate, being polycrystalline in nature, exhibit several preferred in-plane grain orientations. These orientations agree well with a simplified theory of near-coincidence site lattices between Tl2Ba2Ca2Cu3O(x) and MgO.

  6. Dielectric and Electrical Transport Properties of the Fe~(3+)-doped CaCu_3Ti_4O_(12)%Dielectric and Electrical Transport Properties of the Fe~(3+)-doped CaCu_3Ti_4O_(12)

    Institute of Scientific and Technical Information of China (English)

    Zhi Yang; Yue Zhang; Guang You; Kun Zhang; Rui Xiong; Jing Shi

    2012-01-01

    CaCu(3-x)FexTi4O(12)(x=0, 0.015, 0.03, 0.045, 0.06) ceramics were synthesized by sol-gel method. The electrical conduction and dielectric measurements show that the doping of a very small amount of Fe(3+) ions greatly reduces the low-frequency dielectric constants and leakage, and enhances grain resistivity. For the doped samples, the appearance of the strong low-frequency peaks in the spectra of dielectric loss confirms that the doping of Fe(3+) ions induces the contact-electrode effect on ceramic surface. These great changes of electrical properties may originate from the reduced amount of oxygen vacancies by doping Fe(3+)

  7. Laser sintering and dielectric characterization of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics; Sinterizacao a laser e caracterizacao dieletrica de ceramicas de CaCu{sub 3}Ti{sub 4}O{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, L.M.; Barbosa, L.B.; Silva, R.S. [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Fisica. Grupo de Materiais Ceramicos Avancados

    2012-07-01

    Calcium and copper titanate (CaCu{sub 3}Ti{sub 4}O{sub 12} - CCTO) has been prepared by several researchers mainly through conventional ceramic processing. However, other synthesis methods have been tested in the last years. In this work, we have studied the CCTO synthesis by a route based on the Pechini method and its sintering using a new method, in which a CO{sub 2} laser is used as the main heating source. Besides, the dielectric properties of CCTO ceramics were investigated in order to verify the influence of this sintering process on the ceramic properties. The laser sintered ceramics presented high relative density (95 ± 1%), with homogeneous microstructure and single crystalline phase and dielectric constant changing from ∼ 1100 to 2100 (with dielectric loss of ∼ 0.05), when measured at 1 kHz and at room temperature. (author)

  8. Ferroelectric domain structures of epitaxial CaBi2Nb2O9 thin films on single crystalline Nb doped (1 0 0) SrTiO3 substrates

    Science.gov (United States)

    Ahn, Yoonho; Seo, Jeong Dae; Son, Jong Yeog

    2015-07-01

    Epitaxial CaBi2Nb2O9 (CBNO) thin films were deposited on Nb-doped SrTiO3 substrates. The CBNO thin films as a lead-free ferroelectric material exhibit a good ferroelectric property with the remanent polarization of 10.6 μC/cm2. In the fatigue resistance test, the CBNO thin films have no degradation in polarization up to 1×1012 switching cycles, which is applicable for non-volatile ferroelectric random access memories (FeRAMs). Furthermore, piezoresponse force microscopy study (PFM) reveals that the CBNO thin films have larger ferroelectric domain structures than those of PbTiO3 thin films. From the Landau, Lifshiftz, and Kittel's scaling law, it is inferred that the domain wall energy of CBNO thin films is probably very similar to that of the PbTiO3 thin films.

  9. First coil for the SC

    CERN Multimedia

    CERN PhotoLab

    1955-01-01

    The coils for the SC magnet were stored in the large hangar of the Cointrin Airport (to make sure that they would be available before snow and ice would block the roads and canals from Belgium, where they were built).

  10. Monitor of SC beam profiles

    CERN Multimedia

    1977-01-01

    A high-resolution secondary emission grid for the measurement of SC beam profiles. Modern techniques of metal-ceramic bonding, developed for micro-electronics, have been used in its construction. (See Annual Report 1977 p. 105 Fig. 12.)

  11. (La2/5Ba2/5Ca1/5)(Mn(2/5)–NiTi3/5)O3: Rietveld studies, dielectric and magnetic properties of new perovskite-related oxides

    Indian Academy of Sciences (India)

    Pika Jha; Saroj L Samal; Kandalam V Ramanujachary; Samuel E Lofland; Ashok K Ganguli

    2005-10-01

    Oxides of the type (La2/5Ba2/5Ca1/5)(Mn(2/5)–NiTi3/5)O3 (0 ≤ ≤ 0.4) have been synthesized by the ceramic route. All the above oxides have been found to crystallize in the cubic perovskite structure. Rietveld refinement of the Ni-based oxide, (La2/5Ba2/5Ca1/5)(Ni2/5Ti3/5)O3 gave rise to a composition (La0.44Ba0.38Ca0.18) (Ni0.42Ti0.58)O2.85(6) and the refined lattice parameter obtained was 3.9411(2) Å (space group $\\bar{3}$; (2) = 0.026, p = 0.074, p = 0.087). A shift from antiferromagnetic to paramagnetic behaviour is observed with increase in nickel concentration, the Mn-rich phases showing antiferromagnetism around 5 K. There is a systematic decrease in the dielectric constant, and loss tangent with increase in Ni concentration (from = 592 for = 0 to = 78 for = 0.4).

  12. Microstructure and Microwave Dielectric Properties of (1- x)MgAl2O4- x(Ca0.8Sr0.2)TiO3 Ceramics

    Science.gov (United States)

    Huang, Yafei; Yu, Jun; Shen, Chunying; Tang, Mingliang

    2016-10-01

    The microwave dielectric properties of the (1- x)MgAl2O4- x(Ca0.8Sr0.2)TiO3 ( x = 0.02 to 0.10) ceramic system synthesized by the traditional solid-state reaction method have been investigated. Spinel-structured MgAl2O4 was present together with perovskite-structured (Ca0.8Sr0.2)TiO3, and this multiphase system was verified by x-ray diffraction (XRD) and energy spectrum analyses throughout the whole compositional range. With increasing x, the temperature coefficient of resonant frequency ( τ f) and permittivity ( ɛ r) gradually increased. Consequently, near-zero τ f could be obtained for samples with x = 0.08. Excellent microwave dielectric properties with relative permittivity ( ɛ r) of 10.92, quality factor ( Q × f) of 52,563 GHz (at 12.9 GHz), and temperature coefficient of resonant frequency ( τ f) of -5.6 ppm/°C were obtained for 0.92MgAl2O4-0.08(Ca0.8Sr0.2)TiO3 composite sintered at 1440°C for 3 h, making this material a promising candidate for use in global communication satellites and radar detectors.

  13. Magnetic dipole moment of the doubly closed-shell plus one proton nucleus $^{49}$Sc

    CERN Multimedia

    Gaulard, C V; Walters, W; Nishimura, K; Muto, S; Bingham, C R

    It is proposed to measure the magnetic moment of $^{49}$Sc by the Nuclear Magnetic Resonance on Oriented Nuclei (NMR-ON) method using the NICOLE on-line nuclear orientation facility. $^{49}$Sc is the neutron rich, doubly closed-shell, nucleus $^{48}$Ca plus one proton. Results will be used to deduce the effective g-factors in the $^{48}$Ca region with reference to nuclear structure and meson exchange current effects.

  14. Non-ferromagnetic Insulating Interface Region in La0.14Pr0.56Sr0.3MnO3/SrTiO3 and La0.7Ca0.3MnO3/Gd0.7Ca0.3MnO3 Multilayers

    Institute of Scientific and Technical Information of China (English)

    王昕; 刘大猛; 连贵君; 熊光成

    2004-01-01

    La0.14Pr0.56Sr0.3MnO3/SrTiO3 and La0.7Ca0.3MnO3/Gd0.7Ca0.3MnO3 multilayers have been fabricated by using pulsed laser deposition. The insulator-metal transition temperatures of the multilayers decrease with the decreasing thickness of the ferromagnetic layers. It is confirmed from the experiment and analysis that a nonferromagnetic insulating region exists near the interface, which could not be attributed to the roughness of the growth surfaces and disorder of the ferromagnetic layers.

  15. Significantly enhanced ferroelectricity and magnetic properties in (Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3}-modified BiFeO{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Juan; Liu, Xiao Qiang, E-mail: xqliu@zju.edu.cn, E-mail: xmchen59@zju.edu.cn; Chen, Xiang Ming, E-mail: xqliu@zju.edu.cn, E-mail: xmchen59@zju.edu.cn [Laboratory of Dielectric Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2015-05-07

    BiFeO{sub 3} multiferroic ceramics were modified by introducing (Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} to form solid solutions. The single phase structure was easy to be obtained in Bi{sub 1−x}(Sr{sub 0.5}Ca{sub 0.5}){sub x}Fe{sub 1−x}Ti{sub x}O{sub 3} (x = 0.2, 0.25, 0.3, and 0.4) solid solutions. Rietveld refinement of X-ray diffraction data revealed a transition from rhombohedral R3c (x = 0.2, 0.25, and 0.3) to orthorhombic Pnma (x = 0.4). Current density-field (J-E) characteristics indicated that the leakage current density was reduced by three orders of magnitude in Bi{sub 1−x}(Sr{sub 0.5}Ca{sub 0.5}){sub x}Fe{sub 1−x}Ti{sub x}O{sub 3} ceramics. Both the ferroelectricity and magnetic properties were significantly enhanced in the present solid solutions. P-E hysteresis loop measurements with dynamic leakage current compensation methods showed the significantly enhanced ferroelectric properties for x = 0.25 and 0.3 and the paraelectric behavior for x = 0.4. The best ferromagnetic characteristics were achieved in the composition of x = 0.25, where the saturated M-H loop was determined with M{sub r} = 34.8 emu/mol. The improvement of ferroelectricity was mainly due to the suppressed leakage current, and the enhanced magnetism originated from the partial substitution of Fe{sup 3+} by Ti{sup 4+}, which destroyed its previous spiral structure to allow the appearance of a macroscopic magnetization.

  16. Acid-base chemistry in the formation of Mackay-type icosahedral clusters: μ3-acidity analysis of Sc-rich phases of the Sc-Ir system.

    Science.gov (United States)

    Guo, Yiming; Stacey, Timothy E; Fredrickson, Daniel C

    2014-05-19

    The crystal structures of intermetallic phases offer a wealth of geometrical features (helices, multishelled clusters, and host-guest motifs) whose formation has yet to be explained or predicted by chemical theory. A recently developed extension of the acid-base concept to metallic systems, the μ3-acidity model, provides an avenue for developing this understanding for intermetallics formed from transition metals. In this Article, we illustrate how this approach can be used to understand one of the most striking geometrical entities to emerge in intermetallic chemistry, the Mackay cluster of icosahedral quasicrystals. We present μ3-acidity analyses, based on DFT-calibrated Hückel calculations, for a series of Sc-Ir intermetallics: ScIr (CsCl-type), Sc2Ir (Ti2Ni-type), Sc11Ir4, and the Mackay cluster containing phases Sc57Ir13 and Sc44Ir7. We begin by illustrating that a μ3-acidity model correctly predicts that each of these phases is stable relative to disproportionation into their neighboring compounds when a common set of Hückel parameters and d-orbital occupancies is used. Next, we explain these results by developing a relationship between the distance distribution of homoatomic contacts within an atom's coordination sphere and the μ3-neutralization it experiences. For a given average homoatomic distance, the role of heteroatomic contacts is higher when the distribution of homoatomic contacts is narrower. This effect is key to the strength of the acid-base neutralization of the Sc-rich phases, where the Sc atoms find a scarcity of Ir atoms from which to obtain neutralization. Under these circumstances, Sc-Ir contacts should be maximized, whereas the number and distance variations of the Sc-Sc contacts should be minimized. These expectations are borne out by the observed crystal structures. In particular, the Mackay clusters of Sc57Ir13 and Sc44Ir7, in which a central Ir atom is icosahedrally coordinated by a pentagonal dodecahedral array of face-sharing Sc

  17. Enhanced ferroelectric and piezoelectric properties of (1-x)BaZr0.2Ti0.8O3-xBa0.7Ca0.3TiO3 thin films by sol-gel process

    Science.gov (United States)

    Huang, Ling; Dai, Ying; Wu, Yaxiong; Pei, Xinmei; Chen, Wen

    2016-12-01

    Lead free (1-x)BaZr0.2Ti0.8O3-xBa0.7Ca0.3TiO3 (BZT-xBCT) thin films were successfully deposited on Pt/Ti/SiO2/(100)Si substrates via the sol-gel process. Both structural and electric properties of the thin films demonstrated the strong composition dependence. The BZT-xBCT thin film with x = 0.3 exhibited excellent electric properties with a large piezoelectric coefficient, d33 of 280 pm/V and a high remnant polarization, Pr of 12 μC/cm2. The enhanced ferroelectric and piezoelectric properties of BZT-xBCT thin films were primarily attributed to the composition close to the triple point of the morphotropic phase boundaries (MPB) system, where the coexisting of rhombohedral and tetragonal phases takes place.

  18. Study on Pb-Free High-Performance Piezoelectric Material Ba(Ti0.8Zr0.2)O3-x-(Ba0.7Ca0.3)TiO3 Single Crystal and Thin Films%高性能无铅压电材料Ba(Ti0.8Zr0.2)O3-x-(Ba0.7Ca0.3)TiO3单晶和薄膜的制备

    Institute of Scientific and Technical Information of China (English)

    王增梅; 赵宽; 郭新立

    2012-01-01

    Pb-free Ba(Ti0.8Zr0.2)O3-x-(Ba0.7Ca0.3)TiO3 with Morphotropic Phase Boundary, MPB composition has ex- cellent piezo-and ferroelectric properties, therefore it has received extensive attention as its potential application. In this paper, the film with MPB composition was fabricated by sol-gel method and single crystal was also tried by floating-zone method. The phase was confirmed by XRD, and surface morphology was characterized by AFM. The electric hysteresis loop was measured by TFAnalyzer2000HS. Finally, we analyzed the influence of growth atmosphere on the crystal quality and ultraviolet-visible transmittance spectrum.%具有三相点准同型相界附近成分的Ba(Ti0.8Zr0.2)O3-x-(Ba0.7Ca0.3)TiO3无铅压电材料,具有优异的铁电、压电性能,作为一种具有潜在应用前景的无铅压电材料得到广泛关注。利用溶胶一凝胶法制备了该成分的薄膜以及尝试了利用浮区单晶炉的单晶生长工艺。利用XRD对薄膜和生长的晶体样品进行了物相鉴定;用AFM表征了薄膜的表面形貌;用TFAnalyz-er2000HS铁电测试系统测试了其电滞回线;还分析了气氛对晶体生长和紫外一可见透过光谱的影响。

  19. Relaxor ferroelectric properties of the (1-2 x)BiScO3 · xPbTiO3 · xPbMg1/3Nb2/3O3 (0.30 ≤ x ≤ 0.46) system

    Science.gov (United States)

    Bush, A. A.; Kamentsev, K. E.; Bekhtin, M. A.; Segalla, A. G.

    2017-01-01

    X-ray diffraction, dielectric, piezoelectric, and pyroelectric studies have been performed on ceramic samples of (1-2 x)BiScO3 · xPbTiO3 · xPbMg1/3Nb2/3O3 (0.30 ≤ x ≤ 0.46) perovskite-like solid solutions. The solid solution symmetry was found to vary from the rhombohedral ( x ≤ 0.38) to tetragonal ( x ≥ 0.42) as x increases. The samples with 0.30 < x ≤ 0.42 have properties characteristic of relaxor ferroelectrics, namely the existence of a wide peak in the temperature dependence of the dielectric permittivity at T mɛ = 390-440 K that shifts to higher temperatures as the frequency increases, narrow unsaturated dielectric hysteresis loops, and an electric field-induced transition to the ferroelectric state at 318 K. The observed features of the dielectric, piezo-, and pyroelectric properties of these solid solutions are explained by the fact that they are relaxor ferroelectrics.

  20. Effect of La2O3-Dopant on Microstructure and Microwave Dielectric Properties of CaO-MgO-Nb2O5-TiO2 System Ceramics

    Institute of Scientific and Technical Information of China (English)

    Wang Hao; Chen Wen; Liu Tao

    2005-01-01

    La2O3-doped CaO-MgO-Nb2O5-TiO2 system ceramics were prepared by solid-state ceramic technique. The microstructure and microwave dielectric properties of CaO-MgO-Nb2O5-TiO2-La2O3 ceramics can be adjusted by varying the amount of La3+ ions. The results show that the replacement of Ca2+ by La3+ at A-site of the ceramics can increase the quality factor Q*f value as well as the temperature coefficient of resonant frequency τf and decrease the dielectric constant εr. With increase of La3+ contents, the dielectric constant decreases from 57 to 35 and Q*f value increases from 33400 GHz to 35000 GHz (at 7.6 GHz). Meanwhile, the temperature coefficient of resonant frequency is improved towards near zero. The dielectric properties of these compounds are related to octahedra tilting due to deficient vacancies at A-site.

  1. Effects of CaBi4Ti4O15 and Rare-earth Oxide Doping on Microstructure and Dielectric Properties of BaTiO3 Ceramics%钛酸铋钙和稀土复合掺杂对BaTiO3陶瓷微结构和介电性能的影响

    Institute of Scientific and Technical Information of China (English)

    王丽娜; 陈国华

    2011-01-01

    研究了稀土及CaBi4Ti4O15(CBT)的复合掺杂对BaTiO3(BT)陶瓷微结构及介电性能的影响.结果表明:单独添加CBT使晶粒细化,促进了陶瓷的烧结致密化,居里温度随着CBT含量的增加(≤0.5mol%)而逐渐移向高温端;当CBT含量由0.3 mol%增加到0.5 mol%时,BT陶瓷的电容量变化率逐渐减小;当CBT含量超过0.5mol%时,电容量变化率又增大.在BaTiO3-CBT(BT-CBT)基础上单独添加1.0mol% LaO3,四方率减小,居里点移向低温端;保持La2O3掺杂量不变,随着CeO2含量的增加,BT-CBT陶瓷的晶胞体积呈现先减小后增大的变化趋势,四方率保持不变;1.0mol% La2O3和0.01mol% CeO2掺杂BT-CBT(0.5 mol%)陶瓷在- 55℃和125℃的电容变化率分别为- 14.78%和- 11.44%,完全符合EIA X7R标准,有望用于X7R型多层陶瓷电容器的制备.

  2. Fabrication of (111-oriented Ca0.5Sr0.5IrO3/SrTiO3 superlattices—A designed playground for honeycomb physics

    Directory of Open Access Journals (Sweden)

    Daigorou Hirai

    2015-04-01

    Full Text Available We report the fabrication of (111-oriented superlattice structures with alternating 2m-layers (m = 1, 2, and 3 of Ca0.5Sr0.5IrO3 perovskite and two layers of SrTiO3 perovskite on SrTiO3(111 substrates. In the case of m = 1 bilayer films, the Ir sub-lattice is a buckled honeycomb, where a topological state may be anticipated. The successful growth of superlattice structures on an atomic level along the [111] direction was clearly demonstrated by superlattice reflections in x-ray diffraction patterns and by atomically resolved transmission electron microscope images. The ground states of the superlattice films were found to be magnetic insulators, which may suggest the importance of electron correlations in Ir perovskites in addition to the much discussed topological effects.

  3. Fabrication of (111)-oriented Ca{sub 0.5}Sr{sub 0.5}IrO{sub 3}/SrTiO{sub 3} superlattices—A designed playground for honeycomb physics

    Energy Technology Data Exchange (ETDEWEB)

    Hirai, Daigorou [Department of Physics, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan); Matsuno, Jobu [RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198 (Japan); Takagi, Hidenori [Department of Physics, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan); Max-Plank-Institute for solid state research, Heisenbergstrasse 1, Stuttgart 70569 (Germany)

    2015-04-01

    We report the fabrication of (111)-oriented superlattice structures with alternating 2m-layers (m = 1, 2, and 3) of Ca{sub 0.5}Sr{sub 0.5}IrO{sub 3} perovskite and two layers of SrTiO{sub 3} perovskite on SrTiO{sub 3}(111) substrates. In the case of m = 1 bilayer films, the Ir sub-lattice is a buckled honeycomb, where a topological state may be anticipated. The successful growth of superlattice structures on an atomic level along the [111] direction was clearly demonstrated by superlattice reflections in x-ray diffraction patterns and by atomically resolved transmission electron microscope images. The ground states of the superlattice films were found to be magnetic insulators, which may suggest the importance of electron correlations in Ir perovskites in addition to the much discussed topological effects.

  4. Low-temperature sintered ZnNb{sub 2}O{sub 6}–CaTiO{sub 3} ceramics with near-zero τ{sub f}

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Mei; Li, Yuxia [Key Laboratory for Robot and Intelligent Technology of Shandong Province, College of Electrical Engineering and Automation, Shandong University of Science and Technology, Qingdao 266590 (China); Dou, Gang, E-mail: dougang521@163.com [Key Laboratory for Robot and Intelligent Technology of Shandong Province, College of Electrical Engineering and Automation, Shandong University of Science and Technology, Qingdao 266590 (China); Gong, Shuping [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-10-15

    The phases, microstructure and microwave dielectric properties of ZnNb{sub 2}O{sub 6}–xCaTiO{sub 3} ceramics with BaCu(B{sub 2}O{sub 5}) glass additions prepared by solid state reaction method were charactered by using X-ray diffraction, Scanning electron microscopy and Advantest network analyzer. The τ{sub f} of ZnNb{sub 2}O{sub 6} was modified to near 0 ppm °C{sup −1} by incorporating CaTiO{sub 3} with opposite τ{sub f} values on the basis of Lichtenecker empirical rule. The microwave dielectric properties of ZnNb{sub 2}O{sub 6}–xCaTiO{sub 3} (x = 8.0 wt.%) samples with BaCu(B{sub 2}O{sub 5}) glass additives sintered in 900–1000 °C were investigated, and the results indicated that the behaviors of the ε{sub r} and Q × f were associated with the sintering temperature and the amount of BaCu(B{sub 2}O{sub 5}) glass. The sintering temperature of the ceramics was reduced to 950 °C from 1175 °C. Addition of 5.0 wt.% BaCu(B{sub 2}O{sub 5}) glass in ZnNb{sub 2}O{sub 6}–xCaTiO{sub 3} (x = 8.0 wt.%) ceramics sintered at 950 °C showed excellent dielectric properties of ε{sub r} = 20.2, Q × f = 14,100 GHz (f = 7.3 GHz) and τ{sub f} = 0 ppm °C{sup −1}. Moreover, the material had a chemical compatibility with silver, which represented a promising candidate materials for low-temperature-co-fired ceramics applications. - Highlights: • The τ{sub f} of ZnNb{sub 2}O{sub 6} was modified to near 0 ppm °C{sup −1} by incorporating CaTiO{sub 3}. • The sintering temperature of ZnNb{sub 2}O{sub 6}–xCaTiO{sub 3} ceramics with BCB was reduced to 950 °C. • The good dielectric properties of ε{sub r} = 20.2, Q × f = 14,100 GHz, τ{sub f} = 0 ppm °C{sup −1} were achieved. • It represented a promising candidate materials for LTCC applications.

  5. Mg-TiB2中间合金和Ca对AZ91D镁合金组织和性能的影响%Effect of Mg-TiB2 master alloy and Ca on microstructure and properties of AZ91D magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    韩辉; 陈阳; 刘生发; 陈欣

    2011-01-01

    The microstructures and properties of AZ91D magnesium alloy with Mg-50%TiB2 (mass faction) and Ca were studied using SEM, EDS and XRD. It is found that combining addition of 0.7%TiB2 and 0.1%Ca to AZ91D magnesium alloy leads to the α-Mg grain size decreasing from 240 to 46 μm. Based on the EDS test results and calculation of the planar disregistry between TiB2 and α-Mg, TiB2 particles can act as the heterogeneous nucleus of primary α-Mg phase. Ca is pushed onto the solid/liquid interface and enriched at grain boundarries during solidification, which leads to the grain refinement due to the restriction of grain growth. The microstructural refinement of AZ91D magnesium alloy produces significant improvement of mechanical properties and corrosion resistance.%采用SEM、EDS和XRD等测试手段,研究Mg-50%TiB2(质量分数)中间合金和碱土金属元素Ca对AZ91D镁合金组织和性能的影响.结果表明:0.7%TiB2和0.1%Ca可以显著细化AZ91D镁合金的枝晶组织和晶粒,α-Mg的平均晶粒尺寸由240 μm下降至46 μm.通过能谱分析及面错配度的计算证实:TiB2颗粒可作为初生α-Mg的良好异质形核核心.碱土金属元素Ca在晶界处富集,阻碍了α-Mg晶粒生长,对晶粒细化起到了一定的作用.显微组织的细化使合金的强韧性明显提高,并对耐腐蚀性能有较大改善.

  6. Structural properties of CaTi 1-x(Nb 2/3Li 2/3) xO 3-δ (CNLTO) and CaTi 1-x(Nb 1/2Ln 1/2) xO 3 (Ln=Fe (CNFTO), Bi (CNBTO)), modified dielectric ceramics for microwave applications

    Science.gov (United States)

    Costa, R. C. S.; Bruno Costa, A. D. S.; Freire, F. N. A.; Santos, M. R. P.; Almeida, J. S.; Sohn, R. S. T. M.; Sasaki, J. M.; Sombra, A. S. B.

    2009-05-01

    This paper presents an investigation of the structural characteristics of Nb 1/2Bi 1/2 (CNBTO), Nb 1/2Fe 1/2 (CNFTO) and Nb 2/3Li 1/3 (CNLTO) substitution into the B-site of calcium titanate ceramics. The modified CaTiO 3 (CTO) ceramics were prepared by the conventional solid-state method. The compounds were investigated, by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDXS). The X-ray analysis shows that all samples have an orthorhombic structure. The refinement analysis of all samples were also performed and discussed in this paper. For all studied samples, a Raman mode at 805 cm -1 was detected and its intensity increases as the substitution increases. The dielectric permittivity and loss at microwave frequencies (MW) were investigated. The CNLTO phase, present the highest dielectric constant ( k=35.8) at 3.9 GHz with loss (tg α=7×10 -3). The lowest value of k=25.7 ( f=4.8 GHz) and tg α=3×10 -3, was obtained for the CNFTO phase. These measurements confirm the possible use of such material for microwave devices like dielectric resonator antennas.

  7. CaCu{sub 3}Ti{sub 4}O{sub 12} thin films on conductive oxide electrode: A comparative study between chemical and physical vapor deposition routes

    Energy Technology Data Exchange (ETDEWEB)

    Catalano, Maria R.; Malandrino, Graziella [Dipartimento di Scienze Chimiche, Universita di Catania, and INSTM, UdR Catania, Viale A. Doria 6, 95125 Catania (Italy); Bongiorno, Corrado [Istituto per la Microelettronica e Microsistemi, IMM-CNR, Strada VIII 5, 95121 Catania (Italy); Toro, Roberta G. [Istituto per lo Studio dei Materiali Nanostrutturati, ISMN-CNR, Via dei Taurini, 19, 00185 Roma (Italy); Fiorenza, Patrick [Istituto per la Microelettronica e Microsistemi, IMM-CNR, Strada VIII 5, 95121 Catania (Italy); Bodeux, Romain [Laboratoire LEMA, UMR 6157 CNRS/CEA, Universite F. Rabelais, Parc de Grandmont, 37200 Tours (France); STMicroelectronics, R and D, Rue Pierre et Marie Curie, 37000 Tours (France); Wolfman, Jerome; Gervais, Monique; Lambert, Cecile Autret; Gervais, Francois [Laboratoire LEMA, UMR 6157 CNRS/CEA, Universite F. Rabelais, Parc de Grandmont, 37200 Tours (France); Lo Nigro, Raffaella, E-mail: raffaella.lonigro@imm.cnr.it [Istituto per la Microelettronica e Microsistemi, IMM-CNR, Strada VIII 5, 95121 Catania (Italy)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer Dielectrics growth and characterization is one of the most hot topics of materials science and microelectronics. Black-Right-Pointing-Pointer CaCu{sub 3}Ti{sub 4}O{sub 12} perovskite, recently, demonstrated to possess peculiar dielectric properties (Science, 2001, 293, 673-676). Black-Right-Pointing-Pointer To date no deep discussion on the growth processes, properties and perspective of CCTO thin films has been proposed. Black-Right-Pointing-Pointer Our paper is an effective example of interdisciplinarity, since the comparison between PLD and MOCVD has been addressed. Black-Right-Pointing-Pointer Great attention has been paid to CaCu{sub 3}Ti{sub 4}O{sub 12} film/substrate interfaces since dielectric properties are strongly affected. - Abstract: Metal Organic Chemical Vapor Deposition (MOCVD) and Pulsed Laser Deposition (PLD) techniques have been used for the growth of CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) thin films on La{sub 0.9}Sr{sub 1.1}NiO{sub 4}/LaAlO{sub 3} (LSNO/LAO) stack. (1 0 0) oriented CCTO films have been formed through both deposition routes and film complete structural and morphological characterizations have been carried out using several techniques (X-ray diffraction, scanning electron microscopy, energy-filtered transmission electron microscopy). The comparative study demonstrated some differences at the CCTO/LSNO interfaces depending on the adopted deposition technique. Chemical/structural modification of the LSNO electrode probably occurred as a function of the different oxygen partial pressure used in the PLD and MOCVD processes.

  8. TiO2对高钙生料易烧性的影响研究%Research on impact of TiO2 on the burnability of high CaO raw meal

    Institute of Scientific and Technical Information of China (English)

    徐利军; 胡水江; 徐君; 樊佳能; 李生初

    2012-01-01

    应用甘油乙醇法、DTA、XRD、SEM等方法对掺入Ti02的水泥高钙生料易烧性进行试验研究.研究表明:TiO2在较低温度对改善易烧性效果不明显,但在较高温度1350℃具有显著的改善作用;在试验条件下,w(Ti02)=2%的试样的易烧性最好,且C3S结晶完整.

  9. Structural studies of CaAl{sub 12}O{sub 19}, SrAl{sub 12}O{sub 19}, La{sub 2/3+δ}Al{sub 12-δ}O{sub 19}, and CaAl{sub 10}NiTiO{sub 19} with the hibonite structure; indications of an unusual type of ferroelectricity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jun; Medina, Elena A.; Sleight, Arthur W.; Subramanian, M.A. [Oregon State University, Corvallis, OR (United States). Dept. of Chemistry; Stalick, Judith K. [National Institute of Standards and Technology (NIST), Gaithersburg, MD (United States). Center for Neutron Research

    2016-08-01

    Various oxides with the hibonite structure were synthesized and structurally analyzed using powder neutron diffraction. The structure of CaAl{sub 12}O{sub 19} at 298 and 11 K shows dipoles that are apparently too dilute to order unless subjected to a suitable electric field. Magnetoplumbites, such as BaFe{sub 12}O{sub 19}, are isostructural with hibonite. These compounds possess ferromagnetic properties, which combined with the electric dipoles may influence multiferroic behavior. Our SrAl{sub 12}O{sub 19} sample showed two distinct hexagonal phases, a major phase with the normal hibonite structure and a minor phase having a closely related structure. Our sample of the defect hibonite phase La{sub 2/3+δ}Al{sub 12-δ}O{sub 19} shows a distinctly higher δ value (0.25) vs. that reported (∝ 0.15) for samples made from the melt. Finally, we used to advantage the negative scattering length of Ti to determine the site occupancies of Ni and Ti in CaAl{sub 10}NiTiO{sub 19}.

  10. Electrical and piezoelectric properties of BiFeO3 thin films grown on SrxCa1−xRuO3-buffered SrTiO3 substrates

    KAUST Repository

    Yao, Yingbang

    2012-06-01

    (001)-oriented BiFeO 3 (BFO) thin films were grown on Sr xCa 1-xRuO 3- (SCRO; x = 1, 0.67, 0.33, 0) buffered SrTiO 3 (001) substrates using pulsed laser deposition. The microstructural, electrical, ferroelectric, and piezoelectric properties of the thin films were considerably affected by the buffer layers. The interface between the BFO films and the SCRO-buffer layer was found to play a dominant role in determining the electrical and piezoelectric behaviors of the films. We found that films grown on SrRuO 3-buffer layers exhibited minimal electrical leakage while films grown on Sr 0.33Ca 0.67RuO 3-buffer layers had the largest piezoelectric response. The origin of this difference is discussed. © 2012 American Institute of Physics.

  11. Homogeneous interface-type resistance switching in Au/La0.67Ca0.33MnO3/SrTiO3/F(:)SnO2heterojunction memories

    Institute of Scientific and Technical Information of China (English)

    Zhang Ting; Ding Ling-Hong; Zhang Wei-Feng

    2012-01-01

    La0.67Ca0.33MnO3 thin films are fabricated on fluorine-doped tin oxide conducting glass substrates by a pulsed laser deposition technique with SrTiO3 used as a buffer layer.The current-voltage characteristics of the heterojunctions exhibit an asymmetric and resistance switching behaviour.A homogeneous interface-type conduction mechanism is also reported using impedance spectroscopy.The spatial homogeneity of the charge carrier distribution leads to fieldinduced potential-barrier change at the Au-La0.67Ca0.33MnO3 interface and a concomitant resistance switching effect.The ratio of the high resistance state to the low resistance state is found to be as high as 1.3 × 104% by simulating the AC electric field.This colossal resistance switching effect will greatly improve the signal-to-noise ratio in nonvolatile memory applications.

  12. Magnetic moment of {sup 48}Sc

    Energy Technology Data Exchange (ETDEWEB)

    Ohtsubo, T., E-mail: tohtsubo@np.gs.niigata-u.ac.jp; Kawamura, Y.; Ohya, S. [Niigata University, Department of Physics (Japan); Izumikawa, T. [Niigata University, Radioisotope Center (Japan); Nishimura, K. [Toyama University, Faculty of Engineering (Japan); Muto, S. [Neutron Science Laboratory, KEK (Japan); Shinozuka, T. [Tohoku University, Cyclotron and Radioisotope Center (Japan)

    2007-11-15

    Nuclear magnetic resonances were measured for {sup 48}Sc and {sup 44m}Sc oriented at 8 mK in an Fe host metal. The magnetic hyperfine splitting frequencies at an external magnetic field of 0.2 T were determined to be 63.22(11) MHz and 64.81(1) MHz for {sup 48}Sc and {sup 44m}Sc, respectively. With the known magnetic moment of {mu}({sup 44m}Sc)=+3.88 (1) {mu}{sub N}, the magnetic moment of {sup 48}Sc is deduced as {mu}({sup 44}Sc)=+3.785(12) {mu}{sub N}. The measured magnetic moment of {sup 48}Sc is discussed in terms of the shell model using the effective interactions.

  13. 2010 ARRA Lidar: Hampton County (SC)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Provide high density LiDAR elevation data map of Hampton County, SC. Provide Bare Earth DEM (vegetation removal) of Hampton County, SC.

  14. Xemilofiban: SC 54684A, xemlofiban.

    Science.gov (United States)

    2003-01-01

    Xemilofiban [SC 54684, SC 54684A (HCl), xemlofiban], a glycoprotein IIb/IIIa antagonist, is an orally available prodrug of a non-peptide mimetic of the tetrapeptide RGDF. It is converted to the active metabolite, SC 54701 (the free base form of SC 54701A). Development was initiated by Searle (Monsanto). Searle became part of Pharmacia Corporation, which was acquired by, and merged into, Pfizer in April 2003. Searle had co-development and co-marketing agreements with Sankyo in Japan; these have been discontinued. In January 2003, Pharmacia donated the intellectual property for xemilofiban to Western Michigan University. In February 2003, Western Michigan University granted an exclusive worldwide licence of xemilofiban to VDDI Pharmaceuticals (formerly Virtual Drug Development Inc.). Xemilofiban was in a phase III clinical trial, the Evaluation of Xemilofiban in Controlling Thrombotic Events (EXCITE) trial, with Searle (Monsanto) in the US and Europe for the treatment of thrombosis in patients with unstable angina pectoris and acute myocardial infarction undergoing angioplasty. However, as xemilofiban demonstrated no significant clinical benefit, Searle discontinued its development. In Japan, Sankyo discontinued the development of xemilofiban for thrombosis at phase II following Searle's decision to drop the project. VDDI Pharmaceuticals plans to develop xemilofiban in cardiovascular disorders following on from the phase III studies completed by Pharmacia; a restructured dosing schedule and narrowed patient selection will be used. VDDI has research facilities worldwide and will utilise facilities in Ireland for the European clinical development programme; research facilities in the Southwest Michigan Innovation Center are planned while the head office of VDDI is based in Tennessee. Xemilofiban is in phase III development for the treatment of cardiovascular disease in conjunction with percutaneous coronary intervention.

  15. Structural, Dielectric and Complex Impedance Spectroscopy Studies of Lead Free Ca0.5 +xNd0.5-x(Ti0.5Fe0.5)O3

    Institute of Scientific and Technical Information of China (English)

    M.R.Shah; A.K.M.Akther Hossain

    2013-01-01

    Structural and various electrical properties of polycrystalline Ca0.5+xNd0.5-x(Ti0.5Fe0.5)O3,prepared by standard solid state reaction technique,were studied.Formation of single phase orthorhombic structure of the compositions was confirmed by X-ray diffraction study.The composition dependence of lattice parameters,density and microstructural study show that they vary significantly with Ca content.The dielectric measurements were carried out at room temperature as function of frequency and composition.The experimental results reveal that the dielectric constant (ε') increases with increasing Ca content.Similar behavior is observed for the dielectric loss (tanδ) and ac conductivity (σac).In complex impedance analysis it is observed that the real part (Z') vs imaginary part (Z") graph exhibits a tendency of formation of a single semicircular arc for each composition of samples.Different parameters were determined by fitting the experimental data in Cole-Cole empirical formula.A dominance of grain boundary resistance (Rgb) is observed.The Rgb decreases with increasing Ca content.The high ε' observed in present samples are suitablefor fabrication of devices.

  16. Atomic site preferences and its effect on magnetic structure in the intermetallic borides M{sub 2}Fe(Ru{sub 0.8}T{sub 0.2}){sub 5}B{sub 2} (M=Sc, Ti, Zr; T=Ru, Rh, Ir)

    Energy Technology Data Exchange (ETDEWEB)

    Brgoch, Jakoah, E-mail: jrbrgoc@gmail.com [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States); Mahmoud, Yassir A. [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States); Miller, Gordon J., E-mail: gmiller@iastate.edu [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States)

    2012-12-15

    The site preference for a class of intermetallic borides following the general formula M{sub 2}Fe(Ru{sub 0.8}T{sub 0.2}){sub 5}B{sub 2} (M=Sc, Ti, Zr; T=Ru, Rh, Ir), has been explored using ab initio and semi-empirical electronic structure calculations. This intermetallic boride series contains two potential sites, the Wyckoff 2c and 8j sites, for Rh or Ir to replace Ru atoms. Since the 8j site is a nearest neighbor to the magnetically active Fe atom, whereas the 2c site is a next nearest neighbor, the substitution pattern should play an important role in the magnetic structure of these compounds. The substitution preference is analyzed based on the site energy and bond energy terms, both of which arise from a tight-binding evaluation of the electronic band energy, and are known to influence the locations of atoms in extended solids. According to these calculations, the valence electron-rich Rh and Ir atoms prefer to occupy the 8j site, a result also corroborated by experimental evidence. Additionally, substitution of Rh or Ir at the 8j site results in a modification of the magnetic structure that ultimately results in larger local magnetic moment on the Fe atoms. - Graphical abstract: The site preference for electron rich atoms to occupy the 8j (gray) site is identified in these intermetallic borides, while the magnetic structure is modified as a function of the substituted atoms band center. Highlights: Black-Right-Pointing-Pointer We identify the energetics dictating the site preference in a series of intermetallic borides. Black-Right-Pointing-Pointer Establish substitution rules for use in future directed synthetic preparations. Black-Right-Pointing-Pointer Identified changes in magnetic structure that accompany the site preference.

  17. Effect of Sb2O3 on the electrical properties of Ba0.9Ca0.1Zr0.1Ti0.9O3 ceramics fabricated using nanocrystals seed

    Science.gov (United States)

    Parjansri, P.; Intatha, U.; Guo, R.; Bhalla, A. S.; Eitssayeam, S.

    2016-09-01

    This work was to investigate the effects of antimony oxide (Sb2O3) on the electrical properties of Ba0.9Ca0.1Zr0.1Ti0.9O3 (BCZT) ceramics and was prepared by adding 1 mol% of BCZT nanocrystals. The seed is nanocrystals of BCZT which was synthesized by the molten salt method. The ceramics powders were prepared by the mixed oxide method using BaCO3, CaCO3, ZrO2, TiO2 as starting materials, and the BCZT seed was added as nanocrystal for induce phase transition. They were doped with x mol% Sb2O3 ( x = 0.0-0.5). Results indicated that all samples show pure perovskite phase. The Sb2O3 enhanced the electrical properties of the ceramic systems. Excellent values of a dielectric constant ( ɛ r) at room temperature ( T r) were 4086 with sample of x = 0.5, and at Curie temperature ( T c) was 15,485 for samples with x = 0.1. The highest remnant polarization ( P r), piezoelectric charge coefficient ( d 33), piezoelectric voltage coefficient ( g 33), electromechanical coefficient for planar mode ( k p) and thickness mode ( k t) values were 6.3 μC/cm2, 346 pC/N, 15.6 × 10-3 Vm/N, 42 and 41 %, respectively, which were obtained for the sample of x = 0.2 mol% Sb.

  18. Sintering behaviour and microwave dielectric properties of a new complex perovskite: ($1−x$)(Sr$_{0.3}$Ca$_{0.427}$Nd$_{0.182}$)TiO$_{3−x}$SmAlO$_3$ ceramics

    Indian Academy of Sciences (India)

    JING JING QU; FEI LIU; XING WEI; CHANG LAI YUAN; XIAN PEI HUANG

    2016-12-01

    Structural features and microwave dielectric properties of ($1−x$)(Sr$_{0.3}$Ca$_{0.427}$Nd$_{0.182}$)TiO$_{3−x}SmAlO$_{3}($0.05 \\le x \\le 0.4$) ceramics were investigated. X-ray diffraction patterns illustrated that solid solutions with the orthorhombic perovskite were shown to be formed in the ranges of $0.05 \\le x \\le 0.4$. Moreover, the dielectric constant ($\\epsilon_r$) of sintered ceramics had a quasi-linear decrease with the increase in SmAlO$_3$ content. A certain amount of Sm and Al substitution for A- and B-sites could substantially improve the quality factor ($Qf$) of the ceramics. Increasing the oxygen octahedral distortion led to a decrease in the temperature coefficient of the resonant frequency ($\\tau_f$) from 216.3 to $−$34.8 ppm $^{\\circ}$C$^{−1}$. Additionally, optimized microwave dielectric properties can be achieved for the specimens using 0.75(Sr$_{0.3}$Ca$_{0.427}Nd$_{0.182}$)TiO$_3$–0.25SmAlO$_3$ ceramics [$\\epsilon_r \\sim 58.3$, $Qf \\sim 18800$ GHz (at 4.65 GHz) and$\\tau_f \\sim 2.3$ ppm $^{\\circ}$C$^{−1}$] after being sintered at 1500$^{\\circ}$C for 4 h.

  19. Crystal Structure, Piezoelectric and Dielectric Properties of (Li, Ce)4+, Nb5+ and Mn2+ Co-doped CaBi4Ti4O15 High-Temperature Ceramics

    Science.gov (United States)

    Xin, Deqiong; Chen, Qiang; Wu, Jiagang; Bao, Shaoming; Zhang, Wen; Xiao, Dingquan; Zhu, Jianguo

    2016-07-01

    Bismuth-layered structured ceramics Ca0.85(Li,Ce)0.075Bi4Ti4- x Nb x O15-0.01MnCO3 were prepared by the conventional solid-state reaction method. The evolution of microstructure and corresponding electrical properties were studied. All the samples presented a single bismuth layered-structural phase with m = 4, indicating that (Li, Ce)4+, Nb5+ and Mn2+ adequately enter into the pseudo-perovskite structure and form solid solutions. It was found that Ca0.85(Li,Ce)0.075Bi4Ti3.98Nb0.02O15-0.01MnCO3 (CBTLCM-0.02Nb) ceramics possess the optimum electrical properties. The piezoelectric coefficient d 33, dielectric constant ɛ r, loss tan δ, planar electromechanical coupling factor k p and Curie-temperature T C of CBTLCM-0.02Nb ceramics were found to be ˜19.6 pC/N, 160, 0.16%, 8.1% and 767°C, respectively. Furthermore, the thermal depoling behavior demonstrates that the d 33 value of x = 0.02 content remains at 16.8 pC/N after annealing at 500°C. These results suggest that the (Li, Ce)4+-, Nb5+- and Mn2+-doped CBT-based ceramics are promising candidates for high-temperature piezoelectric applications.

  20. Ti substituted La{sub 0.67}Ca{sub 0.33}MnO{sub 3} ortho-perovskites: Dominant role of local structure on the electrical transport and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Seetha Lakshmi, L. [XS and CGS, Materials Science Division, Indira Gandhi Centre For Atomic Research, Kalpakkam, 603102 Tamil Nadu (India)], E-mail: slaxmi73@gmail.com; Rawat, R. [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452 017, Madhya Pradesh (India); Sridharan, V.; Sastry, V.S. [XS and CGS, Materials Science Division, Indira Gandhi Centre For Atomic Research, Kalpakkam, 603102 Tamil Nadu (India)

    2008-02-15

    We report the effects of local structure on the electrical transport and magnetic properties of La{sub 0.67}Ca{sub 0.33}Mn{sub 1-x}Ti{sub x}O{sub 3} (0{<=}x{<=}0.10) system. Linear increase in the lattice parameters, consequent expansion of unit cell and a monotonic decrease in the relative Mn{sup 4+} concentration with x suggest that Ti{sup 4+} predominantly replaces Mn{sup 4+} in La{sub 0.67}Ca{sub 0.33}Mn{sub 1-x}Ti{sub x}O{sub 3} (x{<=}0.10). The ferromagnetic-metallic ground state modifies to a glassy insulator for x{>=}0.05. No field induced metallic state could be discerned for x=0.10 even at a field of 8 T and at as low a temperature as 4.2 K. Ti substitution significantly enhances the colossal magnetoresistance (CMR) effect. Both the metal to insulator transition temperature and Curie temperature (T{sub c}) decrease at a rate of {approx}26 K/at% up to x=0.05. T{sub c} levels off for higher compositions. Modification of the major carrier concentration (decreased Mn{sup 4+} concentration) seems to be insufficient to account for the observed reduction in the transition temperatures. This in turn emphasizes the significance of local structural effects: systematic elongation of the Mn-O bond lengths and decrease of Mn-O-Mn angles leading to strong suppression of itinerant ferromagnetism and metallicity of the compounds. The additional features in the ac susceptibility, viz., a broad shoulder just below T{sub c} followed by a sharp decrease in the susceptibility signal at low temperatures and a non-closure of MR at zero field as high as {approx}75% at 5 K indicate a frustrated magnetic ground state for x=0.07. Based on the inter-comparison of the structural, electrical transport and magnetic properties of the Mn site substituted La{sub 0.67}Ca{sub 0.33}MnO{sub 3} with iso-valent diamagnetic and paramagnetic ions, we argue that local structural effects have a decisive role to play, compared to the local spin coupling effects, in the ferromagnetic-metallic ground

  1. Materials Characterization of High-Temperature Epoxy Resins: SC-79 and SC-15/SC-79 Blend

    Science.gov (United States)

    2011-03-01

    Army composite applications. SC-15 is a toughened commercial vacuum-assisted resin transfer molding ( VARTM ) resin produced by Applied Poleramic Inc...very well in VARTM processes and has good damage resistance in structural and ballistic applications. However, the relatively low glass transition...low-viscosity, two-phase toughened, cycloaliphatic amine–cured commercial VARTM resin system designed to be easy to handle and have a long processing

  2. Chemically anchoring of TiO2 coating on OH-terminated Mg3(PO3)2 surface and its influence on the in vitro degradation resistance of Mg-Zn-Ca alloy

    Science.gov (United States)

    Cao, Guoqin; Wang, Lijie; Fu, Zhenya; Hu, Junhua; Guan, Shaokang; Zhang, Caili; Wang, Liguo; Zhu, Shijie

    2014-07-01

    Surface treatment is of particular interest to slow down the in vitro degradation of Mg-based implants. In this work, micro arc oxidation (MAO) coating was fabricated on Mg-Zn-Ca alloy which has been developed by our group especially for the application of bio-implants. Evident improvement in corrosion resistance was obtained although the MAO coating was porous. In order to further diminish the contact with SBF, a composite coating was prepared by introducing a TiO2 layer by liquid phase deposition (LPD) method on the MAO pre-treated alloy. The coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results of the potentiodynamic polarization experiments showed that, compared with the bare alloy, the corrosion potential of TiO2/MAO/alloy increased from -1.771 to -1.607 V. At the same time, the corrosion current density decreased from 1.43 × 10-4 A cm-2 to 5.69 × 10-7 A cm-2. The improvement of degradation resistance in SBF was ascribed to both barrier effect and enhanced interface condition. The OH-terminated MAO layer surface can make the TiO2 layer anchor tightly on the MOA surface. The chemical bonding of composite layer induced by Mg2+ cations bridges was also analyzed.

  3. Biomimetic Multispiked Connecting Ti-Alloy Scaffold Prototype for Entirely-Cementless Resurfacing Arthroplasty Endoprostheses—Exemplary Results of Implantation of the Ca-P Surface-Modified Scaffold Prototypes in Animal Model and Osteoblast Culture Evaluation

    Directory of Open Access Journals (Sweden)

    Ryszard Uklejewski

    2016-06-01

    Full Text Available We present here—designed, manufactured, and tested by our research team—the Ti-alloy prototype of the multispiked connecting scaffold (MSC-Scaffold interfacing the components of resurfacing arthroplasty (RA endoprostheses with bone. The spikes of the MSC-Scaffold prototype mimic the interdigitations of the articular subchondral bone, which is the natural biostructure interfacing the articular cartilage with the periarticular trabecular bone. To enhance the osteoinduction/osteointegration potential of the MSC-Scaffold, the attempts to modify its bone contacting surfaces by the process of electrochemical cathodic deposition of Ca-P was performed with further immersion of the MSC-Scaffold prototypes in SBF in order to transform the amorphous calcium-phosphate coating in hydroxyapatite-like (HA-like coating. The pilot experimental study of biointegration of unmodified and Ca-P surface-modified MSC-Scaffold prototypes was conducted in an animal model (swine and in osteoblast cell culture. On the basis of a microscope-histological method the biointegration was proven by the presence of trabeculae in the interspike spaces of the MSC-Scaffold prototype on longitudinal and cross-sections of bone-implant specimens. The percentage of trabeculae in the area between the spikes of specimen containing Ca-P surface modified scaffold prototype observed in microCT reconstructions of the explanted joints was visibly higher than in the case of unmodified MSC-Scaffold prototypes. Significantly higher Alkaline Phosphatase (ALP activity and the cellular proliferation in the case of Ca-P-modified MSC-Scaffold pre-prototypes, in comparison with unmodified pre-prototypes, was found in osteoblast cell cultures. The obtained results of experimental implantation in an animal model and osteoblast cell culture evaluations of Ca-P surface-modified and non-modified biomimetic MSC-Scaffold prototypes for biomimetic entirely-cementless RA endoprostheses indicate the

  4. Elastic, piezoelectric, and dielectric properties of Ba(Zr0.2Ti0.8)O3-50(Ba0.7Ca0.3)TiO3 Pb-free ceramic at the morphotropic phase boundary

    Science.gov (United States)

    Xue, Dezhen; Zhou, Yumei; Bao, Huixin; Zhou, Chao; Gao, Jinghui; Ren, Xiaobing

    2011-03-01

    There is an urgent demand for high performance Pb-free piezoelectrics to substitute for the current workhorse, the lead zirconate titanate (PZT) family. Recently, a triple point (also tricritical point) type morphotropic phase boundary (MPB) in Pb-free Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 system has been reported that shows equally as excellent piezoelectricity as soft PZT at room temperature (Liu and Ren6). In the present study, we measured a full set of elastic, piezoelectric, and dielectric properties for the MPB composition, Ba(Zr0.2Ti0.8)O3-50(Ba0.7Ca0.3)TiO3 (BZT-50BCT), by using a resonance method. The resonant method gives piezoelectric properties d33 = 546 pC/N, g33 = 15.3 × 10-3 Vm/N, electromechanical coupling factor k33 = 65%, and the elastic constant s33E = 19.7 × 10-12 m2/N, c33E = 11.3 × 1010 N/m2, which are close to the properties of soft PZT (PZT-5A). Furthermore, the piezoelectric coefficients (k33, d33), the ferroelectric properties (coercive field, remnant polarization), and the elastic constants (s33D, s33E, c33D, c33E) were also determined as a function of temperature ranging from -50 to 60°C. Our results show that the properties are optimal around MPB temperature (room temperature) and decrease with deviations from the MPB temperature. Nevertheless, the piezoelectric coefficient d33 can maintain an appreciable level of 93 pC/N even at -50°C. The high piezoelectric properties can be ascribed to the low polarization anisotropy as well as the elastic softening at MPB.

  5. Natural perovskite: (CaII0.95 (1CeIII0.011 (2NaI0.010 (4(FeIII0.022 (2TiIV0.98 (1O3

    Directory of Open Access Journals (Sweden)

    Nelson G. Fernandes

    2008-09-01

    Full Text Available A natural sample of perovskite (calcium caesium sodium iron titanium oxide from the Tapira Alkaline Complex in southeastern Brazil was found by electron microprobe analysis to have the chemical formula (Ca2+0.95 (1Ce3+0.011 (2Na+0.010 (4(Fe3+0.022 (2Ti4+0.98 (1O2−3 and by IR spectroscopy to be an anhydrous mineral. Oxygen anions are arranged around Ti4+ in an almost perfect octahedron and around Ca2+ in a distorted 12-fold polyhedron.

  6. Structural phase transition in early growth of Bi2Sr2CaCu2O8+x films on SrTiO3 substrates

    Science.gov (United States)

    Abrecht, M.; Ariosa, D.; Onellion, M.; Margaritondo, G.; Pavuna, D.

    2002-02-01

    We used pulsed laser deposition, with a Bi2Sr2CaCu2O8+x target, to grow films ranging from (1/4) to 10 unit cells thick. We studied these films, and reference Bi2Sr2CaCu2O8+x single crystal samples, using angle-integrated photoemission, core level photoemission, and x-ray diffraction. The data indicate that all films exhibit a metallic-like Fermi edge in the photoemission data. More strikingly, a structural phase transition occurs at a nominal Bi2Sr2CaCu2O8+x thickness of approximately one unit cell, converting the precursor Bi2O2.33 highly coherent thin film into a Bi2Sr2CaCu2O8+x structure.

  7. Non-linear dielectric behaviour and glass phase in Sr{sub 1-x}Ca{sub x}TiO{sub 3} (x=0.002 and x=0.003)

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, J.L.; Lacerda-Aroso, M.T. [Departamento de Fisica, Escola de Ciencias, Universidade do Minho, 4709 Braga (Portugal); Chaves, M.R.; Almeida, A. [Departamento de Fisica, IMAT (nucleo IFIMUP), CFUP, Faculdade de Ciencias da Universidade do Porto, R do Campo Alegre, 687, 4150 Porto (Portugal); Maglione, M. [Laboratoire de Physique du Solide, Universite de Bourgogne, P21004 Dijon (France)

    1999-02-08

    This work reports a study of the temperature and electric field dependence of the dielectric constant of strontium calcium titanate. The first part of the paper is focused on the analysis of a mean-field model for the polar clusters generated by the random impurities of calcium. It is shown that the dipolar moments within each cluster can be represented by an equivalent quantum two-level system. General expressions for the temperature and field dependence of the Edward-Anderson order parameter and of the electrical polarization are given. Analytical solutions are also obtained in the limit of high temperatures and in the limit of high tunnelling frequencies. The second part of the work reports experimental results on the temperature and electric field dependence of the dielectric constant of strontium calcium titanate (SCT: Sr{sub 1-x}Ca{sub x}TiO{sub 3}), measured along the [100] pseudo-cubic direction, in samples with nominal Ca content of x=0.002 and x=0.003. The analysis of the data suggests that for these low Ca concentrations quantum fluctuations prevent the onset of either a ferroelectric or a glass phase. (author)

  8. Investigating the surface reactivity of SiO2-TiO2-CaO-Na2O/SrO bioceramics as a function of structure and incubation time in simulated body fluid.

    Science.gov (United States)

    Li, Y; Coughlan, A; Wren, Anthony W

    2014-08-01

    This study focuses on evaluating the biocompatibility of a SiO2-TiO2-CaO-Na2O/SrO glass and glass-ceramic series. Glass and ceramic samples were synthesized and characterized using X-ray diffraction. Each material was subject to maturation in simulated body fluid over 1, 7 and 30 days to describe any changes in surface morphology. Calcium phosphate (CaP) deposition was observed predominantly on the Na(+) containing amorphous and crystalline materials, with plate-like morphology. The precipitated surface layer was also observed to crystallize with respect to maturation, which was most evident in the amorphous Na(+) containing glasses, Ly-N and Ly-C. The addition of Sr(2+) greatly reduced the solubility of all samples, with limited CaP precipitation on the amorphous samples and no deposition on the crystalline materials. The morphology of the samples was also different, presenting irregular plate-like structures (Ly-N), needle-like deposits (Ly-C) and globular-like structures (Ly-S). Cell culture analysis presented a significant increase in cell viability with the Na(+) materials, 134%, while the Sr(2+) containing glasses, 60-80% and ceramics, 60-85% presented a general reduction in cell viability, however these reductions were not significant.

  9. High-resolution study of the beta decay of {sup 41}Ti

    Energy Technology Data Exchange (ETDEWEB)

    Honkanen, A. [Jyvaeskylae Univ. (Finland). Dept. of Physics; Dendooven, P. [Jyvaeskylae Univ. (Finland). Dept. of Physics; Huhta, M. [Jyvaeskylae Univ. (Finland). Dept. of Physics; Lhersonneau, G. [Jyvaeskylae Univ. (Finland). Dept. of Physics; Lipas, P.O. [Jyvaeskylae Univ. (Finland). Dept. of Physics; Oinonen, M. [Jyvaeskylae Univ. (Finland). Dept. of Physics; Parmonen, J.-M. [Jyvaeskylae Univ. (Finland). Dept. of Physics; Penttilae, H. [Jyvaeskylae Univ. (Finland). Dept. of Physics; Peraejaervi, K. [Jyvaeskylae Univ. (Finland). Dept. of Physics; Siiskonen, T. [Jyvaeskylae Univ. (Finland). Dept. of Physics; Aeystoe, J. [Jyvaeskylae Univ. (Finland). Dept. of Physics

    1997-08-11

    An improved high-resolution study of the beta decay of {sup 41}Ti, produced in the {sup 40}Ca({sup 3}He,2n) reaction at 40 MeV, has been performed at the Ion Guide Isotope Separator On-Line (IGISOL) facility. The beta-delayed radiation was detected by a low-energy charged-particle detector and a large Ge detector for gamma rays. The experimental beta-decay strength and its distribution, extracted from delayed-proton data, are compared with results of shell-model calculations in the sdfp space. The lowest J{sup {pi}}=3/2{sup +}, T=3/2 state in {sup 41}Sc, the isobaric analogue state of the {sup 41}Ti ground state, is estimated to contain 10% isospin impurity. (orig.).

  10. The Influence of Biomimetic Deposition Ca-P Coatings on the Release of Simvastatin from TiO2 Nanotube Array

    Directory of Open Access Journals (Sweden)

    Xie Chunlin

    2016-01-01

    Full Text Available In order to improve the capacity of simvastatin and extend the time of the release of the drug, this experiment adopts bionic-deposition to decorate a layer of octacalcium phosphate (OCP on the face of TiO2 nanotube array,and respectively discusses what are the appropriate parameters of octacalcium phosphate (OCP can be generated. Experiments show that loading a layer of octacalcium phosphate can extend the time of the release of the drug. In addition, the presence of simvastatin on the TiO2 nanotube array will be a certain influence on the morphology of octacalcium phosphate. However, simvastatin can be dissolved into the bionic fluid by using bionic deposition. Therefore, by step concentration soaking and then using this method to load OCP with simvastatin can effectively improve the amount of simvastatin loaded and extend drug release

  11. SHMUTZ & PROTON-DIAMANT H + Irradiated/Written-Hyper/Super-conductivity(HC/SC) Precognizance/Early Experiments Connections: Wet-Graphite Room-Tc & Actualized MgB2 High-Tc: Connection to Mechanical Bulk-Moduli/Hardness: Diamond Hydrocarbon-Filaments, Disorder, Nano-Powders:C,Bi,TiB2,TiC

    Science.gov (United States)

    Wunderman, Irwin; Siegel, Edward Carl-Ludwig; Lewis, Thomas; Young, Frederic; Smith, Adolph; Dresschhoff-Zeller, Gieselle

    2013-03-01

    SHMUTZ: ``wet-graphite''Scheike-....[Adv.Mtls.(7/16/12)]hyper/super-SCHMUTZ-conductor(S!!!) = ``wet''(?)-``graphite''(?) = ``graphene''(?) = water(?) = hydrogen(?) =ultra-heavy proton-bands(???) = ...(???) claimed room/high-Tc/high-Jc superconductOR ``p''-``wave''/ BAND(!!!) superconductIVITY and actualized/ instantiated MgB2 high-Tc superconductors and their BCS- superconductivity: Tc Siegel[ICMAO(77);JMMM 7,190(78)] connection to SiegelJ.Nonxline-Sol.40,453(80)] disorder/amorphous-superconductivity in nano-powders mechanical bulk/shear(?)-moduli/hardness: proton-irradiated diamond, powders TiB2, TiC,{Siegel[Semis. & Insuls.5:39,47, 62 (79)])-...``VS''/concommitance with Siegel[Phys.Stat.Sol.(a)11,45(72)]-Dempsey [Phil.Mag. 8,86,285(63)]-Overhauser-(Little!!!)-Seitz-Smith-Zeller-Dreschoff-Antonoff-Young-...proton-``irradiated''/ implanted/ thermalized-in-(optimal: BOTH heat-capacity/heat-sink & insulator/maximal dielectric-constant) diamond: ``VS'' ``hambergite-borate-mineral transformable to Overhauser optimal-high-Tc-LiBD2 in Overhauser-(NW-periodic-table)-Land: CO2/CH4-ETERNAL-sequestration by-product: WATER!!!: physics lessons from

  12. Academic Training - Pulsed SC Magnets

    CERN Multimedia

    Françoise Benz

    2006-01-01

    2005-2006 ACADEMIC TRAINING PROGRAMME LECTURE SERIES 2, 3, June 29, 30, 31 May, 1, 2 June 11:00-12:00 - Auditorium, bldg 500 Pulsed SC Magnets by M. Wilson Lecture 1. Introduction to Superconducting Materials Type 1,2 and high temperature superconductors; their critical temperature, field & current density. Persistent screening currents and the critical state model. Lecture 2. Magnetization and AC Loss How screening currents cause irreversible magnetization and hysteresis loops. Field errors caused by screening currents. Flux jumping. The general formulation of ac loss in terms of magnetization. AC losses caused by screening currents. Lecture 3. Twisted Wires and Cables Filamentary composite wires and the losses caused by coupling currents between filaments, the need for twisting. Why we need cables and how the coupling currents in cables contribute more ac loss. Field errors caused by coupling currents. Lecture 4. AC Losses in Magnets, Cooling and Measurement Summary of all loss mech...

  13. Main: 3SC2 [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 3SC2 小麦 Bread Wheat Triticum aestivum Serine Carboxypeptidase Ii Chains A And B Nam... 1WHS; X-ray; A=6-260, B=266-418.|PDB; 1WHT; X-ray; A=5-260, B=266-418.|PDB; 3SC2; X-ray; A=1-259, B=266-417...WHDAPRSMLPIYRELIAAGLRIWVFSGDTDAVVPLTATRYSIGALGLPTTTSWYPWYDDQEVGGWSQVYKGLTLVSVRGAGHEVPLHRPRQALVLFQYFLQGKPMPGQTKNAT wheat_3SC2.jpg ...

  14. Structural and electronic properties of epitaxial YBa2Cu3O7-δ-La0.67Ca0.33MnO3 bilayers grown on SrTiO3 (1 1 0) substrates

    Science.gov (United States)

    Mustafa, L.; Driza, N.; Soltan, S.; Le Tacon, M.; Habermeier, H.-U.; Keimer, B.

    2014-10-01

    Epitaxial bilayers of the high-temperature-superconductor YBa2Cu3O7-δ (YBCO) and the ferromagnetic metal La0.67Ca0.33MnO3 (LCMO) were prepared by pulsed laser deposition on (1 1 0)-oriented SrTiO3 substrates, such that the CuO2 planes of YBCO are perpendicular to the YBCO-LCMO interface. X-ray diffraction and Raman scattering demonstrate complete (1 1 0) orientation of both YBCO and LCMO overlayers. The resistivity and magnetization of the bilayer films are highly anisotropic. The critical temperatures for superconductivity and ferromagnetism as well as the saturation magnetization exhibit modest reductions compared to corresponding bulk values.

  15. Multiferroic and magnetoelectric properties of Ba0.85Ca0.15Zr0.1Ti0.9O3-CoFe2O4 core-shell nanocomposite

    Science.gov (United States)

    Kumar, Ajith S.; Lekha, C. S. Chitra; Vivek, S.; Saravanan, Venkata; Nandakumar, K.; Nair, Swapna S.

    2016-11-01

    Lead-free magnetoelectric (ME) composites with remarkable ME coupling are required for the realization of eco-friendly multifunctional devices. This work demonstrates the ME properties of Ba0.85Ca0.15Zr0.1Ti0.9O3-CoFe2O4 (BCZT-CFO) core-shell composites synthesized via co-sol-gel technique. Room temperature ferroelectric and ferromagnetic characterization have shown that the samples are magnetic and ferroelectric along with an adequate magnetoelectric coupling of 12.15 mV/(cm Oe). The strong dependence of electric parameters on applied magnetic DC bias fields demonstrated in ferroelectric and magnetoelectric measurements provide a framework for the development of potential magnetoelectric devices. Also, the high sensitivity of magnetoelectric coupling towards the applied AC magnetic field can be used for its application in magnetoelectric sensors.

  16. Effects of La2O3-B2O3-ZnO additions on the low temperature sintering and microwave dielectric properties of (Ca0.61La0.26) TiO3 ceramics

    Science.gov (United States)

    Chen, Y. W.; Li, E. Z.; Niu, N.; Zou, M. Y.; Duan, S. X.; Zhang, S. R.

    2017-02-01

    The influence of La2O3-B2O3-ZnO (LBZ) additions on the sintering behavior, microstructure, phase composition, and the microwave dielectric properties of (Ca0.61La0.26) TiO3 (CLT) ceramics have been investigated. The results indicate that the LBZ additions could efficiently lower the sintering temperature of the CLT ceramics from 1400°C to 950°C, and excellent microwave properties remain. Small amount of LBZ glass promotes the densification of the CLT ceramics and enhances the microwave dielectric properties. However, excess amount of LBZ glass deteriorates the dielectric properties because of the increasing glass phase. The CLT ceramic with 3 wt. % LBZ additions, sintered at 950°C, exhibit excellent properties: εr= 103.12, Q× f = 8826 GHz(f=3.312 GHz) and τƒ=299.52 ppm/°C.

  17. Rotation of ferromagnetic clusters induced magnetoresistance in the junction composed of La0.9Ca0.1MnO3+δ and 1 wt.% Nb-doped SrTiO3

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A junction composed of ultrathin La0.gCa0.1MnO3+δ (LCMO) film and 1 wt.% Nb-doped SrTiO3 was fabricated and its magnetoresistance (MR) was studied and compared with LCMO film. It was found that the resistance of the junction has a similar dependence on magnetic field as that of the LCMO film: the curvature of R-H curves is upward above Curie temperature (To) and downward below TC. These behaviours strongly suggest that the rotation of ferromagnetic clusters in manganite also causes MR in the corresponding junction. This MR can be qualitatively understood by the change of the width of the barrier induced by the rotation of ferromagnetic clusters. These results suggest a possibility to obtain junctions with large low-field MR.

  18. Growth phenomena of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} thin films deposited on (110) oriented SrTiO{sub 3} substrates

    Energy Technology Data Exchange (ETDEWEB)

    Brecht, E.; Linker, G.; Kroener, T.; Schneider, R.; Geerk, J.; Meyer, O. [Forschungszentrum Karlsruhe GmbH Tech. und Umwelt (Germany). INFP; Traeholt, C. [National Centre for HREM, Laboratory of Materials Science, Delft University of Technology, Rotterdamseweg 137, NL-2628 AL Delft (Netherlands)

    1997-07-30

    Thin films of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} have been deposited on (110) oriented SrTiO{sub 3} substrates by inverted cylindrical magnetron sputtering. In structural studies, two competing growth orientations have been observed: domains with the c-axis oriented perpendicular to the substrate surface and inclined domains with the c-axis almost parallel to the [100]{sub S} and [010]{sub S} directions of the substrate. For both growth orientations, in-plane alignment within the (110){sub S} plane has been achieved. Domains of the different growth orientations are clearly reflected in the surface morphology of the films. (orig.)

  19. Dynamical plasma study during CaCu{sub 3}Ti{sub 4}O{sub 12} and Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} pulsed laser deposition by local thermodynamic equilibrium modelling

    Energy Technology Data Exchange (ETDEWEB)

    Lagrange, J F; Wolfman, J; Motret, O [Laboratoire d' Electrodynamique des Materiaux Avances (LEMA), UMR 6157 CNRS-CEA, Universite Francois Rabelais de Tours, Faculte des Sciences and Techniques, Parc Grandmont - bat. E-37200 Tours (France); Hermann, J [Laboratoire Lasers, Plasmas et Procedes Photoniques (LP3), UMR 6182 CNRS, Universite Aix-Marseille II, 163 Avenue de luminy, C. 917-13288 Marseille (France)

    2010-07-21

    We performed space- and time-resolved plasma diagnostics during pulsed laser deposition of CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) and Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} (BSTO) thin films. A KrF excimer laser irradiation at 248 nm with 25 ns pulse duration irradiates targets with a fluence varying from 1 to 2 J cm{sup -2} under an oxygen pressure varying from 5 to 30 Pa. The plasma is shown to be optically thick and strongly non-uniform during the early expansion stage and the resonance lines Ca II 393 and 396 nm are strongly self-reversed during this time. Plasma temperature, electron density and relative elemental concentrations were obtained by comparing the experimental emission spectra with the spectral radiance computed for a non-uniform plasma in local thermal equilibrium. In this way, it was possible to evaluate very low concentrations of pollutants present in irradiated samples.

  20. Microwave dielectric properties of 0.2SrTiO{sub 3}-0.8Ca{sub 0.61}Nd{sub 0.26}Ti{sub 1−x}Al{sub 4x/3}O{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Jingjing [Department of Information Engineering, Guilin University of Aerospace Technology, Guilin 541004 (China); Liu, Fei, E-mail: liufeiguet@163.com [College of Material Science and Engineering, Central South University, Changsha 410083 (China); Yuan, Changlai [College of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Liu, Xinyu [College of Material Science and Engineering, Central South University, Changsha 410083 (China); College of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Chen, Guohua [College of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China)

    2015-01-15

    Graphical abstract: Dependence of tolerance factor (t), octahedral distortion (Δ) and the resonant frequency (τ{sub f}) as a function of composition (x) of 0.2SrTiO{sub 3}-0.8Ca{sub 0.61}Nd{sub 0.26}Ti{sub 1−x}Al{sub 4x/3}O{sub 3} ceramics sintered at 1520°C for 4 h. - Highlights: • The ST-CNT{sub (1−x)}A{sub 4x/3} ceramics were prepared by solid-state reaction method. • The τ{sub f} values were evaluated by the degree of octahedral distortions (Δ). • The τ{sub f} values could be predicted by the change of tolerance factor (t). • The τ{sub f} values could be predicted by the change of tolerance factor (t). - Abstract: The phase structure, microstructure and the dielectric properties of 0.2SrTiO{sub 3}-0.8Ca{sub 0.61}Nd{sub 0.26}Ti{sub 1−x}Al{sub 4x/3}O{sub 3} (0.2 ≤ x ≤ 0.5) ceramics sintered at 1420–1580 °C with conventional solid-state route had been investigated. It was found that the orthorhombic perovskite phase with a small amount of unknown second phase was obtained in the compositional range of 0.2 ≤ x ≤ 0.5. Partial substitution of Ca{sup 2+} and Nd{sup 3+} by Sr{sup 2+} on the A site resulted in a slight increase in the dielectric constant (ε{sub r}) for Ca{sub 0.61}Nd{sub 0.26}Ti{sub 1−x}Al{sub 4x/3}O{sub 3} ceramics. With an increasing of x, the interchange of Ti{sup 4+} and Al{sup 3+} on the B site caused the increase in quality factor (Q·f). Moreover the temperature coefficient of the resonant frequency (τ{sub f}) gradually reduced to close to zero with a rise of x from 0.2 to 0.5. And the variation of the τ{sub f} values with the change of tolerance factor (t) and oxygen octahedral distortion (Δ) was discussed as well. An optimized microwave dielectric properties with ε{sub r} ∼ 48.3, Q·f ∼ 40,700 GHz (at 4.98 GHz) and τ{sub f} ∼ 3.6 ppm/°C could be obtained as x = 0.5 after being sintered at 1520 °C for 4 h.

  1. Broadband near-infrared quantum-cutting by cooperative energy transfer in Yb{sup 3+}–Bi{sup 3+} co-doped CaTiO{sub 3} for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Li-Tian; Chen, Jun-Qiang; Deng, Chao; Tang, Li; Chen, Dong-Ju; Meng, Jian-Xin, E-mail: tmjx@jnu.edu.cn; Cao, Li-Wei

    2015-08-15

    Highlights: • Broadband NIR QC CaTiO{sub 3}:Yb{sup 3+},Bi{sup 3+} phosphor has been firstly developed. • Co-doping with Bi{sup 3+}, it enhanced the Yb{sup 3+} emission intensity by a factor of 10. • This phosphor could efficiently convert 300–480 nm light to ∼1000 nm light. • The ET processes were involved in CET via two photons QC process. - Abstract: An efficient near-infrared (NIR) quantum-cutting (QC) process which converts broadband ultraviolet-blue into NIR via downconversion (DC) has been demonstrated in CaTiO{sub 3}:Yb{sup 3+},Bi{sup 3+} phosphors for the first time. These phosphors are valuable for use in crystalline Si (c-Si) solar cells, because they efficiently convert 300–480 nm light that is not fully utilized by existing c-Si solar cells into ∼1000 nm NIR light that can be sufficiently absorbed by solar cells. Co-doping with 15% Bi{sup 3+} ions, a significant enhancement in Yb{sup 3+} NIR integrated emission intensity by a factor of 10 is realized. The phosphors were characterized with the photoluminescence excitation (PLE) and the photoluminescence (PL) spectra evidence the presence of energy transfer (ET) processes from Bi{sup 3+}-related charge transfer state to Yb{sup 3+} ions. The dependence of Yb{sup 3+} luminescent intensity on the excitation power was also measured and it demonstrates that the ET processes involve cooperative energy transfer (CET) via two photons QC processes.

  2. Interface-enhanced sensitivity of photoconductivity to the electric current and magnetic field in La0.67Ca0.33MnO3/Nb-SrTiO3 p-n junctions

    Science.gov (United States)

    Wang, S.; Ma, Z. Z.; Xiong, J. J.; Li, C. J.; Hou, Y. H.; Ma, T. X.; Xiong, C. M.; Dou, R. F.; Nie, J. C.

    2016-12-01

    The effects of electric current and magnetic field on the photoconductivity (PC) of La0.67Ca0.33MnO3 (LCMO) films have been investigated within a comparative study on LCMO films on an n-type semiconducting Nb-doped SrTiO3 (NSTO) and insulating SrTiO3 (STO) substrates separately. At room temperature, LCMO on NSTO (LCMO/NSTO) was found to show remarkable PC effect than that on STO (LCMO/STO). More attractive is that, compared with that of LCMO/STO, the room-temperature PC of LCMO/NSTO also shows a high sensitivity to the change of current or magnetic field: for LCMO/NSTO under a light illumination with an intensity of 60 mW/cm2, the increment of current yields a decreases of PC at a rate of 7.6%/μA, while an application of magnetic field of 1.2 T can suppress PC by a percentage as high as ˜20%. In contrast, under the same stimulus of current or field, PC of LCMO/STO remains almost unchanged. The phenomena can be explained based on the interface effects correlated with the photocarrier injection, current shunting, and magnetic tunability occurred at the interface. This work demonstrates that manganite-based heterojunctions with interface engineering are promising for developing a new type of photoelectric device with high sensitivity and multifunctionality.

  3. Population of positive-parity states in Sc53 through one-proton knockout

    Science.gov (United States)

    McDaniel, S.; Gade, A.; Janssens, R. V. F.; Bazin, D.; Brown, B. A.; Campbell, C. M.; Carpenter, M. P.; Cook, J. M.; Deacon, A. N.; Dinca, D.-C.; Freeman, S. J.; Glasmacher, T.; Hansen, P. G.; Kay, B. P.; Mantica, P. F.; Mueller, W. F.; Terry, J. R.; Tostevin, J. A.; Zhu, S.

    2010-02-01

    The one-proton knockout reaction Be9(Ti54,Sc53+γ)X at 72 MeV/nucleon has been measured. The location of the first 3/2- state at 2110(3) keV was confirmed, and new γ-ray transitions were observed at 1111(2), 1273(2), 1539(4), and 2495(5) keV. Large spectroscopic strength to excited states in Sc53 was found and attributed to the knockout of sd-shell protons.

  4. 46 CFR 7.70 - Folly Island, SC to Hilton Head Island, SC.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Folly Island, SC to Hilton Head Island, SC. 7.70 Section... BOUNDARY LINES Atlantic Coast § 7.70 Folly Island, SC to Hilton Head Island, SC. (a) A line drawn from the southernmost extremity of Folly Island to latitude 32°35′ N. longitude 79°58.2′ W. (Stono Inlet Lighted...

  5. Synthesis and properties of Yb:Sc2O3 transparent ceramics

    Institute of Scientific and Technical Information of China (English)

    JIANG Benxue; HU Chen; LI Jiang; KOU Huamin; SHI Yun; LIU Wenbin; PAN Yubai

    2011-01-01

    Yb:Sc2O3 transparent ceramics were fabricated by solid-state reaction and vacuum sintering method.CaO was added as sintering aids by a high energy ball milling.Transparent nearly-fully dense samples were obtained after 1840 ℃ sintering.Using transmitted-light microscope we get the grain sizes are more than 1 00 μm.Using spectrophotometer we get the absorption coefficient centered at 975 nm was 2.65 cm-1.The phosphorescence spectra showed that the line-widths (FWHM) at 975 and 1041 nm were about 4 and 10 nm and the lifetime of Yb ions in Sc2O3 transparent ceramics was about 883 μs.According to the absorption and fluorescence band centers of Yb:Sc2O3 transparent ceramics,the level scheme of Yb3+ ions in Sc2O3 ceramics could be gotten.

  6. Influences of MnO2-TiO2-CaO-La2O3 Composite Additives on Properties of Alumina Ceramics Prepared by Low-Temperature Sintering%MnO2-TiO2-CaO-La2O3复相添加剂对低温烧结氧化铝陶瓷性能的影响

    Institute of Scientific and Technical Information of China (English)

    胡继林; 刘鑫; 曹宇; 丁常泽; 周新星

    2011-01-01

    采用MnO2-TiO2-CaO-La2O3体系复相添加剂作为氧化铝陶瓷的烧结助剂,采用模压成型工艺,研究了不同的烧结温度对95氧化铝陶瓷性能的影响.采用XRD和SEM对氧化铝陶瓷试样的晶相组成和微观形貌进行了表征.结果表明,在1450℃烧结时,样品已基本烧结致密,样品的综合性能指标最佳,收缩率为28.5%,体积密度达到3.78 g·cm-3,抗弯强度达到357.12MPa,洛氏硬度值达到78.0.%The effects of different sintering temperatures on the properties of 95 alumina ceramics prepared by mould pressing, using MnO2TiO2CaO-Las=2O3 heterogeneous additive as sintering aids, were studied. Phase compositions and morphologies of alumina ceramic samples were characterized by XRD and SEM. The results show that the samples have almost been densely sintered and their composite properties are the best when sintered at 1450℃. The shrinkage is 28.5% and the bulk density is 3.78g.cm-3. The bending strength and Rockwell hardness reach 357.12MPa and 78.0 separately.

  7. Cs3ScCl6

    Directory of Open Access Journals (Sweden)

    Matthew D. Ward

    2014-06-01

    Full Text Available Crystals of tricaesium scandium(III hexachloride were obtained as a side product from the reaction of U, SnCl2, Sc, and S in a CsCl flux at 1073 K. Cs3ScCl6 crystallizes in the Rb3YCl6 structure type. The asymmetric unit comprises three Cs sites, two Sc sites, and six Cl sites, all of which have site symmetry 1, except for the two Sc sites that have site symmetries of 2 and -1, respectively. The structure is composed of isolated [ScCl6]3− octahedra that are surrounded by Cs+ cations. Two Cs+ cations have interactions with eight Cl− anions, while the third has interactions with ten Cl− anions.

  8. Magneto-transport properties of La0.7Ca0.3MnO3/SrTiO3/La0.7Ce0.3MnO3 tunnel junction

    Indian Academy of Sciences (India)

    P Raychaudhuri; C Mitra; K Dorr; K H Muller; G Kobernik; R Pinto

    2002-05-01

    Hole-doped rare-earth manganite La0.7Ca0.3MnO3 and the electron-doped manganite La0.7Ce0.3MnO3 both show a metal–insulator transition around 250 K associated with a ferromagnetic transition and colossal magnetoresistance. In an earlier publication we have reported the rectifying characteristic of La0.7Ca0.3MnO3/SrTiO3/La0.7Ce0.3MnO3 tunnel junction at room temperature, showing that it is possible to fabricate a diode out of the polaronic insulator regime of doped manganites. Here we report the magneto-transport properties of such a tunnel junction above and below the metal–insulator transition. We show, from the large positive magnetoresistance of the tunnel junction at low temperature, that La0.7Ce0.3MnO3 could be a minority spin carrier ferromagnet. The implication of this observation is discussed.

  9. Improved ferroelectric/piezoelectric properties and bright green/UC red emission in (Li,Ho)-doped CaBi4Ti4O15 multifunctional ceramics with excellent temperature stability and superior water-resistance performance.

    Science.gov (United States)

    Xiao, Ping; Guo, Yongquan; Tian, Mijie; Zheng, Qiaoji; Jiang, Na; Wu, Xiaochun; Xia, Zhiguo; Lin, Dunmin

    2015-10-21

    Multifunctional materials based on rare earth ion doped ferro/piezoelectrics have attracted considerable attention in recent years. In this work, new lead-free multifunctional ceramics of Ca1-x(LiHo)x/2Bi4Ti4O15 were prepared by a conventional solid-state reaction method. The great multi-improvement in ferroelectricity/piezoelectricity, down/up-conversion luminescence and temperature stability of the multifunctional properties is induced by the partial substitution of (Li0.5Ho0.5)(2+) for Ca(2+) ions in CaBi4Ti4O15. All the ceramics possess a bismuth-layer structure, and the crystal structure of the ceramics is changed from a four layered bismuth-layer structure to a three-layered structure with the level of (Li0.5Ho0.5)(2+) increasing. The ceramic with x = 0.1 exhibits simultaneously, high resistivity (R = 4.51 × 10(11)Ω cm), good piezoelectricity (d33 = 10.2 pC N(-1)), high Curie temperature (TC = 814 °C), strong ferroelectricity (Pr = 9.03 μC cm(-2)) and enhanced luminescence. These behaviours are greatly associated with the contribution of (Li0.5Ho0.5)(2+) in the ceramics. Under the excitation of 451 nm light, the ceramic with x = 0.1 exhibits a strong green emission peak centered at 545 nm, corresponding to the transition of the (5)S2→(5)I8 level in Ho(3+) ions, while a strong red up-conversion emission band located at 660 nm is observed under the near-infrared excitation of 980 nm at room temperature, arising from the transition of (5)F5→(5)I8 levels in Ho(3+) ions. Surprisingly, the excellent temperature stability of ferroelectricity/piezoelectricity/luminescence and superior water-resistance behaviors of piezoelectricity/luminescence are also obtained in the ceramic with x = 0.1. Our study suggests that the present ceramics may have potential applications in advanced multifunctional devices at high temperature.

  10. SC-FDMA for mobile communications

    CERN Document Server

    Abd El-Samie, Fathi E

    2013-01-01

    SC-FDMA for Mobile Communications examines Single-Carrier Frequency Division Multiple Access (SC-FDMA). Explaining this rapidly evolving system for mobile communications, it describes its advantages and limitations and outlines possible solutions for addressing its current limitations. The book explores the emerging trend of cooperative communication with SC-FDMA and how it can improve the physical layer security. It considers the design of distributed coding schemes and protocols for wireless relay networks where users cooperate to send their data to the destination. Supplying you with the re

  11. Evaluation of the thermoluminescent detector answers of CaSO{sub 4}:Dy, LiF:Mg,Ti and micro LiF:Mg,Ti in photon clinical beams dosimetry using water simulator; Avaliacao da resposta de detectores termoluminescentes de CaSO4:Dy, LiF:Mg,Ti e microLiF:Mg,Ti na dosimetria de feixes clinicos de fotons utilizando simulador de agua

    Energy Technology Data Exchange (ETDEWEB)

    Matsushima, Luciana C.; Veneziani, Glauco R.; Campos, Leticia L., E-mail: lmatsushima@usp.b, E-mail: veneziani@ipen.b, E-mail: lcrodri@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (GMR/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Gerencia de Metrologia das Radiacoes; Sakuraba, Roberto K.; Cruz, Jose C. da, E-mail: rsakuraba@einstein.b, E-mail: jccruz@einstein.b [Sociedade Beneficente Israelita Brasileira, Sao Paulo, SP (Brazil). Hospital Albert Einstein (HAE)

    2011-10-26

    This paper perform the comparative study of thermoluminescent answer of calcium sulfate dosemeter doped with dysprosium (DaSO{sub 4}:Dy) produced by the IPEN, Sao Paulo, with answer of lithium fluoride dosemeters doped with magnesium and titanium (LiF:Mg, Ti) in the dosimetry of clinical beams of photons (6 and 15 MV) by using water simulator object. Dose-answer curves were obtained for gamma radiation of cobalt-60 in the air and in conditions of electronic equilibrium (plate of PMMA), and clinical photons of CLINAC model 2100C accelerators of the two evaluated hospitals: Hospital das Clinicas of the Faculty of Medicine of Sao Paulo university and Hospital Albert Einstein. It was also evaluated the sensitivity and reproduction of the three dosemeters

  12. z206sc_video_observations

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents video observations from cruise Z206SC for the Santa Barbara Channel region and beyond in southern California. The vector data file is...

  13. z107sc_video_observations

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents video observations from cruise Z107SC for the Santa Barbara Channel region and beyond in southern California. The vector data file is...

  14. Bandwidth challenge teams at SC2003 conference

    CERN Multimedia

    2003-01-01

    Results from the fourth annual High-Performance Bandwidth Challenge, held in conjunction with SC2003, the international conference on high-performance computing and networking which occurred last week in Phoenix, AZ (1 page).

  15. Mechanisms Responsible for the Large Piezoelectricity at the Tetragonal-Orthorhombic Phase Boundary of (1-x)BaZr0.2Ti0.8O3-xBa0.7Ca0.3TiO3 System

    Science.gov (United States)

    Yang, Tao; Ke, Xiaoqin; Wang, Yunzhi

    2016-09-01

    Recently it was found that in the lead-free (1-x)BaZr0.2Ti0.8O3-xBa0.7Ca0.3TiO3 (BZT-xBCT) system, the highest piezoelectric d33 coefficient appears at the tetragonal (T) – orthorhombic (O) phase boundary rather than the O – rhombohedral (R) phase boundary, but the physical origin of it is still unclear. In this work we construct the phase diagram of the BZT-xBCT system using a generic sixth-order Landau free energy polynomial and calculate the energy barrier (EB) for direct domain switching between two variants of the stable low-symmetry ferroelectric phase. We find that the EB at the T-O phase boundary is lower than that at the O-R phase boundary and EB may serve as a rigorous quantitative measure of the degree of polarization anisotropy through Landau potential. The calculations may shed some light on the physical origin of the highest piezoelectric coefficients as well as the softest elastic compliance at the T-O phase boundary observed in experiments.

  16. Mechanisms Responsible for the Large Piezoelectricity at the Tetragonal-Orthorhombic Phase Boundary of (1-x)BaZr0.2Ti0.8O3-xBa0.7Ca0.3TiO3 System.

    Science.gov (United States)

    Yang, Tao; Ke, Xiaoqin; Wang, Yunzhi

    2016-09-16

    Recently it was found that in the lead-free (1-x)BaZr0.2Ti0.8O3-xBa0.7Ca0.3TiO3 (BZT-xBCT) system, the highest piezoelectric d33 coefficient appears at the tetragonal (T) - orthorhombic (O) phase boundary rather than the O - rhombohedral (R) phase boundary, but the physical origin of it is still unclear. In this work we construct the phase diagram of the BZT-xBCT system using a generic sixth-order Landau free energy polynomial and calculate the energy barrier (EB) for direct domain switching between two variants of the stable low-symmetry ferroelectric phase. We find that the EB at the T-O phase boundary is lower than that at the O-R phase boundary and EB may serve as a rigorous quantitative measure of the degree of polarization anisotropy through Landau potential. The calculations may shed some light on the physical origin of the highest piezoelectric coefficients as well as the softest elastic compliance at the T-O phase boundary observed in experiments.

  17. In-situ X-ray diffraction study of stress-induced phase transition of (1 − x)BaZr{sub 0.2}Ti{sub 0.8}O{sub 3}–xBa{sub 0.7}Ca{sub 0.3}TiO{sub 3} in polymer matrix composite

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W., E-mail: spacexuanwu@163.com [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Li, W.L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); National Key Laboratory of Science and Technology on Precision Heat Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China); Feng, Y.; Hou, Y.F.; Xu, D.; Wang, M. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Fei, W.D., E-mail: wdfei@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2014-08-01

    Phase transitions of (1 − x)BaZr{sub 0.2}Ti{sub 0.8}O{sub 3}–xBa{sub 0.7}Ca{sub 0.3}TiO{sub 3} (BZT–xBCT) powders under tensile stress were investigated using in-situ X-ray diffraction (XRD). Uniaxial stress was applied to the designed BZT–xBCT/polyimide composite films during XRD. Under stress, the rhombohedral (R) phase was found to transform into a tetragonal (T) phase, while the [001] direction of the T phase tends to be parallel to the tensile direction. T → R phase transition was not observed in the films upon tensile stress loading, implying that R → T phase transitions may be the decisive factor for the huge piezoelectric response of the BZT–xBCT system. - Highlights: • The in-situ X-ray diffraction was studied on BZT–xBCT during tensile process. • Stress-induced phase transition of BZT–xBCT was observed during tensile process. • R → T phase transition may be the decisive factor for the huge d{sub 33} of BZT–xBCT.

  18. 溶胶-凝胶法制备Ca10(PO4)6(OH)2/TiO2复合涂层及其在模拟生理体液中的行为%HAP/TiO2 Composite Films: Preparation, Characterisation and Their Behaviors in Simulated Body Fluid

    Institute of Scientific and Technical Information of China (English)

    苏冰; 于旭东; 郭连峰; 王成焘

    2005-01-01

    The composite films consisting of hydroxyapatite (HAP) submicron particles embedded in the gel composed of the titania nanoparticles were prepared on commercial Ti6A14V plates with titania buffer layer obtained by a spin-coating technique. The films were calcined in air at various temperatures, and the bioactivities of the films were investigated by immersing them in acellular simulated body fliud (SBF). X-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR), Field emission-scanning electron microscopy(FESEM) and Energy dispersive X-ray (EDS) analysis were employed to investigate the phase formation and structure of the films before and after immersion, and the variations of Ca and P contents in SBF were measured by Inductively Coupled Plasma Spectroscopy(ICP). The results show that the as-prepared films were dense, homogeneous, all well-crystallized, and there was a close interracial bond between the film and the substrate. The characterisatics of the grown layer on the surfaces of the HAP/TiO2 films after immersion in SBF for different periods of time are specially discussed.

  19. Investigation of the structural, optical and dielectric properties of highly (1 0 0)-oriented (Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20})TiO{sub 3} thin films on LaNiO{sub 3} bottom electrode

    Energy Technology Data Exchange (ETDEWEB)

    Pontes, D.S.L. [Laboratorio Interdisciplinar de Eletroquimica e Cerâmica, Department of Chemistry, Universidade Federal de São Carlos, Via Washington Luiz, Km 235, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil); Pontes, F.M., E-mail: fenelon@fc.unesp.br [Department of Chemistry, Universidade Estadual Paulista, P.O. Box 473, 17033-360 Bauru, São Paulo (Brazil); Chiquito, A.J. [NanO LaB, Transporte Eletrônico em Nanoestruturas, Department of Physics, Universidade Federal de São Carlos, Via Washington Luiz, Km 235, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil); Longo, E. [Laboratorio Interdisciplinar de Eletroquimica e Cerâmica, Department of Chemistry, Universidade Federal de São Carlos, Via Washington Luiz, Km 235, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil); Institute of Chemistry, Universidade Estadual Paulista, Araraquara, São Paulo (Brazil)

    2014-07-01

    Highlights: • Highly (h 0 0) oriented LNO and PCST thin films were grown on LAO(1 0 0) substrate. • PCST/LNO/LAO structure shown classic ferroelectric–paraelectric phase transition. • PCST/LNO/LAO structure shows superior dielectric properties. • PCST/LAO films showed a direct allowed optical transition. - Abstract: Highly (1 0 0)-oriented Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LNO/LAO structure was fabricated using a chemical deposition process via spin-coating technique. XRD revealed that both LNO and Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3} films grown on LAO(1 0 0) substrate and LNO/LAO(1 0 0) structure were crystallized to be highly (h 0 0)-oriented, respectively. AFM images revealed smooth surfaces, spherical-shaped grains and a crack-free surface with a roughness of about 3–7 nm. The tetragonal perovskite phase was confirmed by Raman spectroscopy for Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LNO/LAO and Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LAO structures. The optical transmittance of 340 nm thick Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3} films on a LAO(1 0 0) substrate exhibited an average transmittance above 80% in the wavelength range of 500–1000 nm and an optical band gap E{sub g} of 3.56 and 2.87 eV for the direct and indirect transition processes, respectively. The Au/Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LNO/LAO structure has a hysteresis loop with remnant polarization, P{sub r}, of 12 μC/cm{sup 2}, and a coercive field, E{sub c}, of 46 kV/cm for an electric field at 370 kV/cm along with a dielectric constant over 1200.

  20. Sc3N and Sc2C2 encapsulated B40: Smarter than its carbon analogue

    Science.gov (United States)

    Shah, Esha V.; Roy, Debesh R.

    2016-10-01

    A detailed comparative investigation on the recently synthesised B40 and C40 along with their metal nitride (Sc3N)and carbide (Sc2C2) encapsulated endohedral fullerenes, is performed under density functional theory for the first time. The structures, electronic, thermodynamic and magnetic properties of all the considered compounds are explored in detail. The present study identifies borospherene (B40) and its encapsulated nitride (Sc3N@B40) and carbide (Sc2C2@B40) endohedral borofullerenes as the better candidates for future novel nano-applications compared to their carbon bucky ball analogues.

  1. Strain Dependent Electronic Structure and Band Offset Tuning at Heterointerfaces of ASnO3 (A=Ca, Sr, and Ba) and SrTiO3

    Science.gov (United States)

    Baniecki, John D.; Yamazaki, Takashi; Ricinschi, Dan; Van Overmeere, Quentin; Aso, Hiroyuki; Miyata, Yusuke; Yamada, Hiroaki; Fujimura, Norifumi; Maran, Ronald; Anazawa, Toshihisa; Valanoor, Nagarajan; Imanaka, Yoshihiko

    2017-01-01

    The valence band (VB) electronic structure and VB alignments at heterointerfaces of strained epitaxial stannate ASnO3 (A=Ca, Sr, and Ba) thin films are characterized using in situ X-ray and ultraviolet photoelectron spectroscopies, with band gaps evaluated using spectroscopic ellipsometry. Scanning transmission electron microscopy with geometric phase analysis is used to resolve strain at atomic resolution. The VB electronic structure is strain state dependent in a manner that correlated with a directional change in Sn-O bond lengths with strain. However, VB offsets are found not to vary significantly with strain, which resulted in ascribing most of the difference in band alignment, due to a change in the band gaps with strain, to the conduction band edge. Our results reveal significant strain tuning of conduction band offsets using epitaxial buffer layers, with strain-induced offset differences as large as 0.6 eV possible for SrSnO3. Such large conduction band offset tunability through elastic strain control may provide a pathway to minimize the loss of charge confinement in 2-dimensional electron gases and enhance the performance of photoelectrochemical stannate-based devices. PMID:28195149

  2. Improved Electrical Properties of Low-Temperature Sintered Cu Doped Ba0.99Ca0.01Zr0.02Ti0.98O3 Ceramics

    Science.gov (United States)

    Zhang, Yong; Sun, Huajun; Chen, Wen

    2016-10-01

    In this study, a series of Ba0.99Ca0.01Zr0.02Ti0.98O3- x mol.% Cu (BCZT- xCu) ceramics were fabricated with a conventional solid state reaction method. The effects of sintering temperature and doping level of Cu ions on the microstructure development and electrical properties were studied systematically. The optimal sintering temperature could be lowered by 200°C compared to pure BCZT ceramics, due to the addition of Cu. Optimized properties were obtained for BCZT-2.0 mol.% Cu ceramics sintered at 1250°C, showing improved ferroelectric properties with a high remnant polarization ( P r = 8.25 μC/cm2) and a low coercive field ( E c = 0.395 kV/mm). Of particular significance is that the dielectric properties were found to show high thermal stability. The dielectric constant ( {ɛr } ) is within the scope of 1900-2350, while the dielectric loss (tan δ) is in the range of 1.15-2.2% within a temperature range of 30-105°C. In general, the BCZT-2.0Cu ceramics mainly display the characteristic of normal ferroelectrics.

  3. In-situ Electric Field-Induced Modulation of Photoluminescence in Pr-doped Ba0.85Ca0.15Ti0.90Zr0.10O3 Lead-Free Ceramics

    Science.gov (United States)

    Sun, Hai Ling; Wu, Xiao; Chung, Tat Hang; Kwok, K. W.

    2016-06-01

    Luminescent materials with dynamic photoluminescence activity have aroused special interest because of their potential widespread applications. One proposed approach of directly and reversibly modulating the photoluminescence emissions is by means of introducing an external electric field in an in-situ and real-time way, which has only been focused on thin films. In this work, we demonstrate that real-time electric field-induced photoluminescence modulation can be realized in a bulk Ba0.85Ca0.15Ti0.90Zr0.10O3 ferroelectric ceramic doped with 0.2 mol% Pr3+, owing to its remarkable polarization reversal and phase evolution near the morphotropic phase boundary. Along with in-situ X-ray diffraction analysis, our results reveal that an applied electric field induces not only typical polarization switching and minor crystal deformation, but also tetragonal-to-rhombohedral phase transformation of the ceramic. The electric field-induced phase transformation is irreversible and engenders dominant effect on photoluminescence emissions as a result of an increase in structural symmetry. After it is completed in a few cycles of electric field, the photoluminescence emissions become governed mainly by the polarization switching, and thus vary reversibly with the modulating electric field. Our results open a promising avenue towards the realization of bulk ceramic-based tunable photoluminescence activity with high repeatability, flexible controllability, and environmental-friendly chemical process.

  4. Elastic properties of perovskite ATiO{sub 3} (A = Be, Mg, Ca, Sr, and Ba) and PbBO{sub 3} (B = Ti, Zr, and Hf): First principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Pandech, Narasak; Limpijumnong, Sukit, E-mail: sukit@sut.ac.th [School of Physics and NANOTEC-SUT Center of Excellence on Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Synchrotron Light Research Institute, Nakhon Ratchasima 30000 (Thailand); Thailand Center of Excellence in Physics (ThEP Center), Commission on Higher Education, Bangkok 10400 (Thailand); Sarasamak, Kanoknan [College of Nanotechnology, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand)

    2015-05-07

    The mechanical properties of perovskite oxides depend on two metal oxide lattices that are intercalated. This provides an opportunity for separate tuning of hardness, Poisson's ratio (transverse expansion in response to the compression), and shear strength. The elastic constants of series of perovskite oxides were studied by first principles approach. Both A-site and B-site cations were systematically varied in order to see their effects on the elastic parameters. To study the effects of A-site cations, we studied the elastic properties of perovskite ATiO{sub 3} for A being Be, Mg, Ca, Sr, or Ba, one at a time. Similarly, for B-site cations, we studied the elastic properties of PbBO{sub 3} for B being Ti, Zr, or Hf, one at a time. The density functional first principles calculations with local density approximation (LDA) and generalized gradient approximation (GGA) were employed. It is found that the maximum C{sub 11} elastic constant is achieved when the atomic size of the cations at A-site and B-site are comparable. We also found that C{sub 12} elastic constant is sensitive to B-site cations while C{sub 44} elastic constant is more sensitive to A-site cations. Details and explanations for such dependencies are discussed.

  5. In-situ Electric Field-Induced Modulation of Photoluminescence in Pr-doped Ba0.85Ca0.15Ti0.90Zr0.10O3 Lead-Free Ceramics

    Science.gov (United States)

    Sun, Hai Ling; Wu, Xiao; Chung, Tat Hang; Kwok, K. W.

    2016-01-01

    Luminescent materials with dynamic photoluminescence activity have aroused special interest because of their potential widespread applications. One proposed approach of directly and reversibly modulating the photoluminescence emissions is by means of introducing an external electric field in an in-situ and real-time way, which has only been focused on thin films. In this work, we demonstrate that real-time electric field-induced photoluminescence modulation can be realized in a bulk Ba0.85Ca0.15Ti0.90Zr0.10O3 ferroelectric ceramic doped with 0.2 mol% Pr3+, owing to its remarkable polarization reversal and phase evolution near the morphotropic phase boundary. Along with in-situ X-ray diffraction analysis, our results reveal that an applied electric field induces not only typical polarization switching and minor crystal deformation, but also tetragonal-to-rhombohedral phase transformation of the ceramic. The electric field-induced phase transformation is irreversible and engenders dominant effect on photoluminescence emissions as a result of an increase in structural symmetry. After it is completed in a few cycles of electric field, the photoluminescence emissions become governed mainly by the polarization switching, and thus vary reversibly with the modulating electric field. Our results open a promising avenue towards the realization of bulk ceramic-based tunable photoluminescence activity with high repeatability, flexible controllability, and environmental-friendly chemical process. PMID:27339815

  6. Coupling of electric charge and magnetic field via electronic phase separation in (La,Pr,Ca)MnO3/Pb(Mg1/3Nb2/3)O3-PbTiO3 multiferroic heterostructures

    Science.gov (United States)

    Zheng, Ming; Wang, Wei

    2016-04-01

    The electric-field-tunable non-volatile resistivity and ferromagnetism switching in the (La0.5Pr0.5)0.67Ca0.33MnO3 films grown on (111)-oriented 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 ferroelectric single-crystal substrates have been investigated. By combining the 180° ferroelectric domain switching and in situ X-ray diffraction and resistivity measurements, we identify that this voltage control of order parameters stems from the domain switching-induced accumulation/depletion of charge carriers at the interface rather than induced lattice strain effect. In particular, the polarization-induced charge effect (i.e., ferroelectric field effect) is strongly dependent on the magnetic field. This, together with the charge-modulated magnetoresistance and magnetization, reveals the strong correlation between the electric charge and the magnetic field. Further, we found that this coupling is essentially driven by the electronic phase separation, the relative strength of which could be determined by recording charge-tunability of resistivity [ (Δρ/ρ)c h arg e ] under various magnetic fields. These findings present a potential strategy for elucidating essential physics of perovskite manganites and delivering prototype electronic devices for non-volatile information storage.

  7. Pressure-induced electrical and structural anomalies in Pb{sub 1-x}Ca{sub x}TiO{sub 3} thin films grown at various oxygen pressures by chemical solution route

    Energy Technology Data Exchange (ETDEWEB)

    Pontes, F M; Galhiane, M S; Santos, L S; Rissato, S R [Department of Chemistry, Universidade Estadual Paulista (UNESP), PO Box 473, 17033-360, Bauru, SP (Brazil); Pontes, D S L; Longo, E [Chemistry Institute, Universidade Estadual Paulista (UNESP), PO Box 355, 14801-970 Araraquara, SP (Brazil); Leite, E R [LIEC-CMDMC, Department of Chemistry, UFSCar, Via Washington Luiz, km 235, CP-676, CEP-13565-905, Sao Carlos, SP (Brazil); Chiquito, A J; Pizani, P S [Department of Physics, UFSCar-Via Washington Luiz, km 235, CEP-13565-905, Sao Carlos, SP (Brazil); Jardim, R F [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970 Sao Paulo, SP (Brazil); Escote, M T [Centro de Engenharia, Modelagem e Ciencias Sociais Aplicadas, Universidade Federal do ABC, Rua Catequese, 242, CEP 09090-400, Santo Andre, SP (Brazil)], E-mail: fenelon@fc.unesp.br

    2008-06-07

    Lead calcium titanate (Pb{sub 1-x}Ca{sub x}TiO{sub 3} or PCT) thin films have been thermally treated under different oxygen pressures, 10, 40 and 80 bar, by using the so-called chemical solution deposition method. The structural, morphological, dielectric and ferroelectric properties were characterized by x-ray diffraction, FT-infrared and Raman spectroscopy, atomic force microscopy and polarization-electric-field hysteresis loop measurements. By annealing at a controlled pressure of around 10 and 40 bar, well-crystallized PCT thin films were successfully prepared. For the sample submitted to 80 bar, the x-ray diffraction, Fourier transformed-infrared and Raman data indicated deviation from the tetragonal symmetry. The most interesting feature in the Raman spectra is the occurrence of intense vibrational modes at frequencies of around 747 and 820 cm{sup -1}, whose presence depends strongly on the amount of the pyrochlore phase. In addition, the Raman spectrum indicates the presence of symmetry-breaking disorder, which would be expected for an amorphous (disorder) and mixed pyrochlore-perovskite phase. During the high-pressure annealing process, the crystallinity and the grain size of the annealed film decreased. This process effectively suppressed both the dielectric and ferroelectric behaviour. Ferroelectric hysteresis loop measurements performed on these PCT films exhibited a clear decrease in the remanent polarization with increasing oxygen pressure.

  8. Dual-band LTCC antenna based on 0.95Zn2SiO4-0.05CaTiO3 ceramics for GPS/UMTS applications

    Institute of Scientific and Technical Information of China (English)

    窦刚; 李玉霞; 郭梅

    2015-01-01

    In this paper, we present a compact low-temperature co-fired ceramic (LTCC) dual-band antenna by using the elec-tromagnetic coupling effect concept for global positioning system (GPS) and universal mobile telecommunication system (UMTS) applications. The overall dimension of the antenna is 8.6 mm × 13.0 mm × 1.1 mm. It consists of double meander lines and a via hole line. The top meander line operates at the upper band, and the bottom radiating patch is designed for the lower band. The via-hole line is employed to connect the double meander lines. Because of the effect of the coupled line, total dimension of the proposed antenna is greatly reduced. With the 2.5:voltage standing wave ratio (VSWR) impedance bandwidth definition, the lower and upper bands have the bandwidths of 110 MHz and 150 MHz, respectively. The pro-posed antenna is successfully designed, simulated, and analyzed by a high frequency structure simulator (HFSS). And the antenna is manufactured by using the 0.95Zn2SiO4-0.05CaTiO3 ceramics (εr=7.1, tanδ =0.00038) that is prepared by ourselves. The results show that the antenna is compact, efficient, and of near omnidirectional radiation pattern.

  9. Magnetoelectric properties of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 - CoFe2O4 particulate composites

    Science.gov (United States)

    Paul Praveen, J.; Vinitha Reddy, M.; Das, Dibakar

    2016-05-01

    0.7[(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3)]-0.3[CoFe2O4] multiferroic particulate ceramic composite with (0-3) connectivity has been synthesized by wet chemical methods. BCZT-CFO composite showed both polarization-electric field and magnetic hysteresis loops simultaneously at room temperature. A high dielectric constant of 2160 and tangent loss factor of 0.6 has been obtained. Magnetoelectric (ME) voltage coefficient (αME =dE/dH) of the composite was measured as a function of applied d.c magnetic field at different frequencies. At resonance frequency (365kHz) the composite showed a maximum αME of 102mV/cm.Oe. It was observed that the transverse ME coefficient is 1.8 times higher than the longitudinal ME coefficient. The magnetoelectric properties of this composite has been studied in detail in this work and correlated with its structure.

  10. Hydrogen Storage Properties of New Hydrogen-Rich BH3NH3-Metal Hydride (TiH2, ZrH2, MgH2, and/or CaH2) Composite Systems

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Young Joon; Xu, Yimin; Shaw, Wendy J.; Ronnebro, Ewa

    2012-04-19

    Ammonia borane (AB = NH3BH3) is one of the most attractive materials for chemical hydrogen storage due to its high hydrogen contents of 19.6 wt.%, however, impurity levels of borazine, ammonia and diborane in conjunction with foaming and exothermic hydrogen release calls for finding ways to mitigate the decomposition reactions. In this paper we present a solution by mixing AB with metal hydrides (TiH2, ZrH2, MgH2 and CaH2) which have endothermic hydrogen release in order to control the heat release and impurity levels from AB upon decomposition. The composite materials were prepared by mechanical ball milling, and their H2 release properties were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The formation of volatile products from decomposition side reactions, such as borazine (N3B3H6) was determined by mass spectrometry (MS). Sieverts type pressure-composition-temperature (PCT) gas-solid reaction instrument was adopted to observe the kinetics of the H2 release reactions of the combined systems and neat AB. In situ 11B MAS-NMR revealed a destabilized decomposition pathway. We found that by adding specific metal hydrides to AB we can eliminate the impurities and mitigate the heat release.

  11. Batievaite-(Y), Y2Ca2Ti[Si2O7]2(OH)2(H2O)4, a new mineral from nepheline syenite pegmatite in the Sakharjok massif, Kola Peninsula, Russia

    Science.gov (United States)

    Lyalina, L. M.; Zolotarev, A. A.; Selivanova, E. A.; Savchenko, Ye. E.; Krivovichev, S. V.; Mikhailova, Yu. A.; Kadyrova, G. I.; Zozulya, D. R.

    2016-12-01

    Batievaite-(Y), Y2Ca2Ti[Si2O7]2(OH)2(H2O)4, is a new mineral found in nepheline syenite pegmatite in the Sakharjok alkaline massif, Western Keivy, Kola Peninsula, Russia. The pegmatite mainly consists of nepheline, albite, alkali pyroxenes, amphiboles, biotite and zeolites. Batievaite-(Y) is a late-pegmatitic or hydrothermal mineral associated with meliphanite, fluorite, calcite, zircon, britholite-group minerals, leucophanite, gadolinite-subgroup minerals, titanite, smectites, pyrochlore-group minerals, zirkelite, cerianite-(Ce), rutile, behoite, ilmenite, apatite-group minerals, mimetite, molybdenite, and nickeline. Batievaite-(Y) is pale-cream coloured with white streak and dull, greasy or pearly luster. Its Mohs hardness is 5-5.5. No cleavage or parting was observed. The measured density is 3.45(5) g/cm3. Batievaite-(Y) is optically biaxial positive, α 1.745(5), β 1.747(5), γ 1.752(5) (λ 589 nm), 2 V meas. = 60(5)°, 2 V calc. = 65°. Batievaite-(Y) is triclinic, space group P-1, a 9.4024(8), b 5.5623(5), c 7.3784(6) Å, α 89.919(2), β 101.408(2), γ 96.621(2)°, V 375.65(6) Å3 and Z = 1. The eight strongest lines of the X-ray powder diffraction pattern [ d(Å)(I)( hkl)] are: 2.991(100)(11-2), 7.238(36)(00-1), 3.061(30)(300), 4.350(23)(0-1-1), 9.145(17)(100), 4.042(16)(11-1), 2.819(16)(3-10), 3.745(13)(2-10). The chemical composition determined by electron probe microanalysis (EPMA) is (wt.%): Nb2O5 2.25, TiO2 8.01, ZrO2 2.72, SiO2 29.96, Al2O3 0.56, Fe2O3 0.43, Y2O3 11.45, La2O3 0.22, Ce2O3 0.33, Nd2O3 0.02, Gd2O3 0.07, Dy2O3 0.47, Er2O3 1.07, Tm2O3 0.25, Yb2O3 2.81, Lu2O3 0.45, CaO 24.98, MnO 1.31, MgO 0.01, Na2O 1.13, K2O 0.02, F 2.88, Cl 0.19, H2O 6.75 (determined on the basis of crystal structure data), O = (F,Cl) -1.25, total 97.09 wt.%. The empirical formula based on the EPMA and single-crystal structure analyses is (Y0.81Ca0.65Mn0.15Zr0.12Yb0.11Er0.04Fe3+ 0.04Ce0.02Dy0.02Lu0.02La0.01Tm0.01)Σ2.00((H2O)0.75Ca0.70□0.55)Σ2.00Ca2.00(□0.61Na0

  12. Batievaite-(Y), Y2Ca2Ti[Si2O7]2(OH)2(H2O)4, a new mineral from nepheline syenite pegmatite in the Sakharjok massif, Kola Peninsula, Russia

    Science.gov (United States)

    Lyalina, L. M.; Zolotarev, A. A.; Selivanova, E. A.; Savchenko, Ye. E.; Krivovichev, S. V.; Mikhailova, Yu. A.; Kadyrova, G. I.; Zozulya, D. R.

    2016-05-01

    Batievaite-(Y), Y2Ca2Ti[Si2O7]2(OH)2(H2O)4, is a new mineral found in nepheline syenite pegmatite in the Sakharjok alkaline massif, Western Keivy, Kola Peninsula, Russia. The pegmatite mainly consists of nepheline, albite, alkali pyroxenes, amphiboles, biotite and zeolites. Batievaite-(Y) is a late-pegmatitic or hydrothermal mineral associated with meliphanite, fluorite, calcite, zircon, britholite-group minerals, leucophanite, gadolinite-subgroup minerals, titanite, smectites, pyrochlore-group minerals, zirkelite, cerianite-(Ce), rutile, behoite, ilmenite, apatite-group minerals, mimetite, molybdenite, and nickeline. Batievaite-(Y) is pale-cream coloured with white streak and dull, greasy or pearly luster. Its Mohs hardness is 5-5.5. No cleavage or parting was observed. The measured density is 3.45(5) g/cm3. Batievaite-(Y) is optically biaxial positive, α 1.745(5), β 1.747(5), γ 1.752(5) (λ 589 nm), 2V meas. = 60(5)°, 2V calc. = 65°. Batievaite-(Y) is triclinic, space group P-1, a 9.4024(8), b 5.5623(5), c 7.3784(6) Å, α 89.919(2), β 101.408(2), γ 96.621(2)°, V 375.65(6) Å3 and Z = 1. The eight strongest lines of the X-ray powder diffraction pattern [d(Å)(I)(hkl)] are: 2.991(100)(11-2), 7.238(36)(00-1), 3.061(30)(300), 4.350(23)(0-1-1), 9.145(17)(100), 4.042(16)(11-1), 2.819(16)(3-10), 3.745(13)(2-10). The chemical composition determined by electron probe microanalysis (EPMA) is (wt.%): Nb2O5 2.25, TiO2 8.01, ZrO2 2.72, SiO2 29.96, Al2O3 0.56, Fe2O3 0.43, Y2O3 11.45, La2O3 0.22, Ce2O3 0.33, Nd2O3 0.02, Gd2O3 0.07, Dy2O3 0.47, Er2O3 1.07, Tm2O3 0.25, Yb2O3 2.81, Lu2O3 0.45, CaO 24.98, MnO 1.31, MgO 0.01, Na2O 1.13, K2O 0.02, F 2.88, Cl 0.19, H2O 6.75 (determined on the basis of crystal structure data), O = (F,Cl) -1.25, total 97.09 wt.%. The empirical formula based on the EPMA and single-crystal structure analyses is (Y0.81Ca0.65Mn0.15Zr0.12Yb0.11Er0.04Fe3+ 0.04Ce0.02Dy0.02Lu0.02La0.01Tm0.01)Σ2.00((H2O)0.75Ca0.70□0.55)Σ2.00Ca2.00(□0.61Na0.25( H2O

  13. Sc20C60: a volleyballene

    Science.gov (United States)

    Wang, Jing; Ma, Hong-Man; Liu, Ying

    2016-06-01

    An exceptionally stable hollow cage containing 20 scandium atoms and 60 carbon atoms has been identified. This Sc20C60 molecular cluster has a Th point group symmetry and a volleyball-like shape that we refer to below as ``Volleyballene''. Electronic structure analysis shows that the formation of delocalized π bonds between Sc atoms and the neighboring pentagonal rings made of carbon atoms is crucial for stabilizing the cage structure. A relatively large HOMO-LUMO gap (~1.4 eV) was found. The results of vibrational frequency analysis and molecular dynamics simulations both demonstrate that this Volleyballene molecule is exceptionally stable.An exceptionally stable hollow cage containing 20 scandium atoms and 60 carbon atoms has been identified. This Sc20C60 molecular cluster has a Th point group symmetry and a volleyball-like shape that we refer to below as ``Volleyballene''. Electronic structure analysis shows that the formation of delocalized π bonds between Sc atoms and the neighboring pentagonal rings made of carbon atoms is crucial for stabilizing the cage structure. A relatively large HOMO-LUMO gap (~1.4 eV) was found. The results of vibrational frequency analysis and molecular dynamics simulations both demonstrate that this Volleyballene molecule is exceptionally stable. Electronic supplementary information (ESI) available: Sc20C60: a Volleyballene_SI. See DOI: 10.1039/c5nr07784b

  14. Domain structure and phase transition in Sc-doped zirconia

    Science.gov (United States)

    Brunauer, G.; Boysen, H.; Frey, F.; Ehrenberg, H.

    2002-01-01

    The temperature dependence of the domain structure associated with the ferroelastic phase transition (Fm↔R bar 3 m) in ZrO2 doped with 11% Sc2O3 has been determined from a peak shape analysis of high-resolution synchrotron x-ray powder diffraction data. In the temperature region of coexisting phases the observed characteristic anisotropic broadening and asymmetry of the lines is modelled by three different phases: a main rhombohedral phase, a distorted rhombohedral phase with a smaller c/a ratio, and a cubic phase. The latter two are assigned to the internal structure of the domain walls between two adjacent twin domains. The size and amount of the cubic phase show an initially slow increase with temperature followed by a very steep increase and a slow one after that. The size of the (main) rhombohedral domains remains nearly constant, while (micro-) strain in the distorted regions gradually decreases.

  15. Recrystallization and Morphology of Microstructure in Al-Sc Alloys

    Institute of Scientific and Technical Information of China (English)

    Zhang Jun; Zhang Zonghua

    2007-01-01

    Minor addition of Sc to aluminum results in the rapid precipitation of homogeneously distributed Al3Sc dispersoids. The presence of Al3Sc dispersoids is more effective recrystallization inhibitors. Our work established the precipitation of homogeneously distributed Al3Sc dispersoids, which are coherent with the matrix, have the L12 structure. It was also established that the addition of Sc was effective in improving the recrystallization resistance.

  16. Norma Audio Revo SC-/PA-150

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Norma audio是意大利一间顶级HI-Fi音响器材生产商。这款IRevo SC-2/PA-150为正是公司旗下的一款高端型号产品。其中,Revo SC-2前置放大器的放大电路以低噪音、高速和宽频作为设计重点,能反映出音频信号中的每一个细节。

  17. K2SC: K2 Systematics Correction

    Science.gov (United States)

    Aigrain, Suzanne; Parviainen, Hannu; Pope, Benjamin

    2016-05-01

    K2SC (K2 Systematics Correction) models instrumental systematics and astrophysical variability in light curves from the K2 mission. It enables the user to remove both position-dependent systematics and time-dependent variability (e.g., for transit searches) or to remove systematics while preserving variability (for variability studies). K2SC automatically computes estimates of the period, amplitude and evolution timescale of the variability for periodic variables and can be run on ASCII and FITS light curve files. Written in Python, this pipeline requires NumPy, SciPy, MPI4Py, Astropy (ascl:1304.002), and George (ascl:1511.015).

  18. Quaternary equilibrium diagrams ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}-(CaO, MgO, TiO{sub 2}). A powerful tool for the development of new materials by reaction sintering; Diagramas de equilibrio cuaternarios ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}- (CaO, MgO, TiO{sub 2}). Una poderosa herramienta para el desarrollo de nuevos materiales por sinterizacion reactiva

    Energy Technology Data Exchange (ETDEWEB)

    Moya, J. S.; Bartolome, J. F.; Pena, P.

    2011-07-01

    In this paper we set out, discuss and evaluate the work on Mullite-zirconia composites obtained by reaction sintering led and inspired by Salvador de Aza on the basis of ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}-(CaO, MgO, TiO{sub 2}) multicomponent phase equilibrium diagrams. We analyze their impact on different areas of ceramic science and technology such as refractory grogs, aluminum industry, etc. The possible fields of future applications such as dental prosthesis replacing partially stabilized zirconia materials with rare earths are also reported. (Author) 42 refs.

  19. SC83288 is a clinical development candidate for the treatment of severe malaria

    Science.gov (United States)

    Pegoraro, Stefano; Duffey, Maëlle; Otto, Thomas D; Wang, Yulin; Rösemann, Roman; Baumgartner, Roland; Fehler, Stefanie K; Lucantoni, Leonardo; Avery, Vicky M; Moreno-Sabater, Alicia; Mazier, Dominique; Vial, Henri J; Strobl, Stefan; Sanchez, Cecilia P; Lanzer, Michael

    2017-01-01

    Severe malaria is a life-threatening complication of an infection with the protozoan parasite Plasmodium falciparum, which requires immediate treatment. Safety and efficacy concerns with currently used drugs accentuate the need for new chemotherapeutic options against severe malaria. Here we describe a medicinal chemistry program starting from amicarbalide that led to two compounds with optimized pharmacological and antiparasitic properties. SC81458 and the clinical development candidate, SC83288, are fast-acting compounds that can cure a P. falciparum infection in a humanized NOD/SCID mouse model system. Detailed preclinical pharmacokinetic and toxicological studies reveal no observable drawbacks. Ultra-deep sequencing of resistant parasites identifies the sarco/endoplasmic reticulum Ca2+ transporting PfATP6 as a putative determinant of resistance to SC81458 and SC83288. Features, such as fast parasite killing, good safety margin, a potentially novel mode of action and a distinct chemotype support the clinical development of SC83288, as an intravenous application for the treatment of severe malaria. PMID:28139658

  20. Magnet measuring equipment of SC2

    CERN Multimedia

    1974-01-01

    Checking the positioning of the magnet measuring equipment installed between the poles of SC2. The steel structure in front of the magnet is designed to house the rotary condenser and to shield it from the stray magnetic field of the accelerator.

  1. Magnet measuring equipment of SC2

    CERN Multimedia

    1974-01-01

    Checking the positioning of the magnet measuring equipment installed between the poles of SC2. The steel structure in front of the magnet is designed to house the rotary condenser and to shield it from the stray magnetic field of the accelerator. On the left, Marinus van Gulik. (See Photo Archive 7402005 and Annual Report 1974, p. 44.)

  2. The Synchrocyclotron (SC) in building 300

    CERN Multimedia

    Maximilien Brice

    2012-01-01

    The red magnet of CERN's first accelerator, the Synchrocyclotron (SC), has occupied a large part of Hall 300 since it was installed in the late 1950s. The remaining part of the 300-square-metre building has been used as a storage room since the accelerator was shut down in 1990. Now a public exhibition will breathe new life into the hall.

  3. Low-temperature sintering and microwave dielectric properties of Ca[(Li1/3Nb2/3)0.8Ti0.2]3- δ with glass frit added

    Science.gov (United States)

    In, Chi-Seung; Yeo, Dong-Hun; Shin, Hyo-Soon; Nahm, Sahn; Choi, Won-Youl

    2015-04-01

    In accordance with the trend for mobile terminals to be high intensity and to have thinner layers, low temperature co-fired ceramics (LTCC) materials with outstanding dielectric loss characteristics and diverse dielectric constants have been in demand, and the need for high-strength materials that can withstand external shocks has increased. Ca[(Li1/3Nb2/3)1- x Ti x ]O3- δ (CLNT) has a quality factor over 14,000 and τ f ≤ 10 when the dielectric constant is 41 ˜ 46, but its sintering temperature is high at 1150 °C. Therefore, it cannot be used as a LTCC component. This study aimed to lower the sintering temperature to 900 °C by adding a low-melting-point glass such as B2O3·SiO2·BaO and B2O3·SiO2·Al2O3. As the glass content in CLNT was increased from 10 wt% to 20 wt%, the density and the Q·f0 property decreased, and the dielectric constant rose. When B2O3·SiO2·BaO was added to CLNT at 15 wt%, the dielectric constant was found to be 27, the Q·f0 property to be 3470, and the τ f to be -18 ppm/°C. When B2O3·SiO2·Al2O3 was added to CLNT at 10 wt%, the dielectric constant was 20, the Q·f0 property was 3990, and the τ f was -15 ppm/°C. As such, in both cases, excellent dielectric properties were observed.

  4. Dual-band LTCC antenna based on 0.95Zn2SiO4-0.05CaTiO3 ceramics for GPS/UMTS applications

    Science.gov (United States)

    Dou, Gang; Li, Yu-Xia; Guo, Mei

    2015-10-01

    In this paper, we present a compact low-temperature co-fired ceramic (LTCC) dual-band antenna by using the electromagnetic coupling effect concept for global positioning system (GPS) and universal mobile telecommunication system (UMTS) applications. The overall dimension of the antenna is 8.6 mm × 13.0 mm × 1.1 mm. It consists of double meander lines and a via hole line. The top meander line operates at the upper band, and the bottom radiating patch is designed for the lower band. The via-hole line is employed to connect the double meander lines. Because of the effect of the coupled line, total dimension of the proposed antenna is greatly reduced. With the 2.5: voltage standing wave ratio (VSWR) impedance bandwidth definition, the lower and upper bands have the bandwidths of 110 MHz and 150 MHz, respectively. The proposed antenna is successfully designed, simulated, and analyzed by a high frequency structure simulator (HFSS). And the antenna is manufactured by using the 0.95Zn2SiO4-0.05CaTiO3 ceramics (εr = 7.1, tanδ = 0.00038) that is prepared by ourselves. The results show that the antenna is compact, efficient, and of near omnidirectional radiation pattern. Project supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20133718120009), the Natural Science Foundation of Shandong Provence, China (Grant Nos. ZR2013FQ002 and ZR2014FQ006), the China Postdoctoral Science Foundation (Grant No. 2014M551935), the Qingdao Municipality Postdoctoral Science Foundation, China, and the Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents, China (Grant Nos. 2013RCJJ042 and 2014RCJJ052).

  5. CaMn0.875Ti0.125O3 as oxygen carrier for chemical-looping combustion with oxygen uncoupling (CLOU)—Experiments in a continuously operating fluidized-bed reactor system

    KAUST Repository

    Rydén, Magnus

    2011-03-01

    Particles of the perovskite material CaMn0.875Ti0.125O3 has been examined as oxygen carrier for chemical-looping with oxygen uncoupling, and for chemical-looping combustion of natural gas, by 70h of experiments in a circulating fluidized-bed reactor system. For the oxygen uncoupling experiments, it was found that the particles released O2 in gas phase at temperatures above 720°C when the fuel reactor was fluidized with CO2. The effect increased with increased temperature, and with the O2 partial pressure in the air reactor. At 950°C, the O2 concentration in the outlet from the fuel reactor was in the order of 4.0vol%, if the particles were oxidized in air. For the chemical-looping combustion experiments the combustion efficiency with standard process parameters was in the order of 95% at 950°C, using 1000kg oxygen carrier per MW natural gas, of which about 30% was located in the fuel reactor. Reducing the fuel flow so that 1900kg oxygen carrier per MW natural gas was used improved the combustion efficiency to roughly 99.8%. The particles retained their physical properties, reactivity with CH4 and ability to release gas-phase O2 reasonably well throughout the testing period and there were no problems with the fluidization or formation of solid carbon in the reactor. X-ray diffraction showed that the particles underwent changes in their phase composition though. © 2010 Elsevier Ltd.

  6. Fabrication of High Efficiency Dye-Sensitized Solar Cells Based on TiO2 Nanoparticles Embedded in Ti Substrate.

    Science.gov (United States)

    Kim, Kang-Pil; Lee, Sang-Ju; Hwang, Dae-Kue; Kim, Dae-Hwan; Heo, Young-Woo

    2015-01-01

    We have embedded a TiO2 nanoparticle (NP) photoelectrode in a Ti substrate to improve the cell efficiency of conventional TiO2 NP based dye-sensitized solar cells (DSSCs) using Ti substrate. Compared to the conventional standing-type (TiO2 NPs on Ti substrate) DSSCs, the embedded-type (TiO2 NPs embedded in Ti substrate) DSSCs have shown an approximately 35% improvement in power conversion efficiency due to the improvement of J(sc). The embedded-type DSSCs have more charge transport paths than do standing-type DSSCs due to the increase of contact area between the TiO2 NP sidewall and the Ti substrate. This increased contact area decreases the electrical resistance and increases the charge collection efficiency, which leads to the improvement of J(sc). The embedded-type NP-DSSCs are very effective DSSC structures for enhancing the power conversion efficiency of Ti substrate based DSSCs.

  7. Platinum determination by instrumental neutron activation analysis with special reference to the spectral interference of Sc-47 on the platinum indicator nuclide Au-199

    DEFF Research Database (Denmark)

    Alfassi, Z.B.; Probst, T.U.; Rietz, B.

    1998-01-01

    A method of instrumental neutron activation analysis (INAA) is developed for the determination of platinum by the Au-199 daughter of Pt-199 in the presence of the spectral interference from the Sc-47 daughter of Ca-47. The contributions of the Pt and Ca signals to the integral 157-161 keV peak were...

  8. Physical conditions in CaFe interstellar clouds

    OpenAIRE

    Gnacinski, P.; Krogulec, M.

    2007-01-01

    Interstellar clouds that exhibit strong Ca I and Fe I lines were called CaFe clouds. The ionisation equilibrium equations were used to model the column densities of Ca II, Ca I, K I, Na I, Fe I and Ti II in CaFe clouds. The chemical composition of CaFe clouds is that of the Solar System and no depletion of elements onto dust grains is seen. The CaFe clouds have high electron densities n=1 cm^-3 that leads to high column densities of neutral Ca and Fe.

  9. Synthesis, microstructural characterization and optical properties of undoped, V and Sc doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Amezaga-Madrid, P.; Antunez-Flores, W.; Ledezma-Sillas, J.E.; Murillo-Ramirez, J.G.; Solis-Canto, O.; Vega-Becerra, O.E.; Martinez-Sanchez, R. [Centro de Investigacion en Materiales Avanzados S.C. and Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes 120, Chihuahua, Chih., C.P. 31109 (Mexico); Miki-Yoshida, M., E-mail: mario.miki@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados S.C. and Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes 120, Chihuahua, Chih., C.P. 31109 (Mexico)

    2011-06-15

    Research highlights: > Undoped, V and Sc doped ZnO thin films by Aerosol Assisted Chemical Vapour Deposition. > Optimum substrate temperatures of 673 K and 623 K for Sc and V doped films. > Around one third of the dopants in solution were deposited into the films. > Crystallite and grain size decreased with the increase of dopant concentration. > Optical band gap increased from 3.29 to 3.32 eV for undoped to 7 Sc/Zn at. %. - Abstract: Many semiconductor oxides (ZnO, TiO{sub 2}, SnO{sub 2}) when doped with a low percentage of non-magnetic (V, Sc) or magnetic 3d (Co, Mn, Ni, Fe) cation behave ferromagnetically. They have attracted a great deal of interest due to the integration of semiconducting and magnetic properties in a material. ZnO is one of the most promising materials to carry out these tasks in view of the fact that it is optically transparent and has n or p type conductivity. Here, we report the synthesis, microstructural characterization and optical properties of undoped, V and Sc doped zinc oxide thin films. ZnO based thin films with additions of V and Sc were deposited by the Aerosol Assisted Chemical Vapour Deposition method. V and Sc were incorporated separately in the precursor solution. The films were uniform, transparent and non-light scattering. The microstructure of the films was characterized by Grazing Incidence X-ray Diffraction, Scanning Electron Microscopy, and Scanning Probe Microscopy. Average grain size and surface rms roughness were estimated by the measurement of Atomic Force Microscopy. The microstructure of doped ZnO thin films depended on the type and amount of dopant material incorporated. The optical properties were determined from specular reflectance and transmittance spectra. Results were analyzed to determine the optical constant and band gap of the films. An increase in the optical band gap with the content of Sc dopant was obtained.

  10. LHCb Data Replication During SC3

    CERN Multimedia

    Smith, A

    2006-01-01

    LHCb's participation in LCG's Service Challenge 3 involves testing the bulk data transfer infrastructure developed to allow high bandwidth distribution of data across the grid in accordance with the computing model. To enable reliable bulk replication of data, LHCb's DIRAC system has been integrated with gLite's File Transfer Service middleware component to make use of dedicated network links between LHCb computing centres. DIRAC's Data Management tools previously allowed the replication, registration and deletion of files on the grid. For SC3 supplementary functionality has been added to allow bulk replication of data (using FTS) and efficient mass registration to the LFC replica catalog.Provisional performance results have shown that the system developed can meet the expected data replication rate required by the computing model in 2007. This paper details the experience and results of integration and utilisation of DIRAC with the SC3 transfer machinery.

  11. Single chain Fab (scFab fragment

    Directory of Open Access Journals (Sweden)

    Brenneis Mariam

    2007-03-01

    Full Text Available Abstract Background The connection of the variable part of the heavy chain (VH and and the variable part of the light chain (VL by a peptide linker to form a consecutive polypeptide chain (single chain antibody, scFv was a breakthrough for the functional production of antibody fragments in Escherichia coli. Being double the size of fragment variable (Fv fragments and requiring assembly of two independent polypeptide chains, functional Fab fragments are usually produced with significantly lower yields in E. coli. An antibody design combining stability and assay compatibility of the fragment antigen binding (Fab with high level bacterial expression of single chain Fv fragments would be desirable. The desired antibody fragment should be both suitable for expression as soluble antibody in E. coli and antibody phage display. Results Here, we demonstrate that the introduction of a polypeptide linker between the fragment difficult (Fd and the light chain (LC, resulting in the formation of a single chain Fab fragment (scFab, can lead to improved production of functional molecules. We tested the impact of various linker designs and modifications of the constant regions on both phage display efficiency and the yield of soluble antibody fragments. A scFab variant without cysteins (scFabΔC connecting the constant part 1 of the heavy chain (CH1 and the constant part of the light chain (CL were best suited for phage display and production of soluble antibody fragments. Beside the expression system E. coli, the new antibody format was also expressed in Pichia pastoris. Monovalent and divalent fragments (DiFabodies as well as multimers were characterised. Conclusion A new antibody design offers the generation of bivalent Fab derivates for antibody phage display and production of soluble antibody fragments. This antibody format is of particular value for high throughput proteome binder generation projects, due to the avidity effect and the possible use of

  12. The SC gets ready for visitors

    CERN Multimedia

    Antonella Del Rosso

    2012-01-01

    Hall 300, which houses the Synchrocyclotron (SC), CERN’s first accelerator, is getting ready to host a brand-new exhibition. The site will be one of the stops on the new visit itineraries that will be inaugurated for the 2013 CERN Open Day.   The Synchrocyclotron through the years. Just as it did in the late 1950s, when the accelerator was first installed, the gigantic red structure of the Synchrocyclotron's magnet occupies a large part of the 300-square-metre hall. “We have completed the first phase of the project that will give the SC a new lease of life,” says Marco Silari, the project leader and a member of CERN’s Radiation Protection Group. “We have removed all the equipment that was not an integral part of the accelerator. The hall is now ready for the civil-engineering work that will precede the installation of the exhibition.” The SC was witness to a big part of the history of CERN. The accelerator produced ...

  13. Domain wall motion and electromechanical strain in lead-free piezoelectrics: Insight from the model system (1 − x)Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–x(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} using in situ high-energy X-ray diffraction during application of electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Tutuncu, Goknur [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States); Li, Binzhi [Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, California 95616 (United States); Bowman, Keith [Illinois Institute of Technology, Armour College of Engineering, Chicago, Illinois 60616 (United States); School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Jones, Jacob L., E-mail: JacobJones@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2014-04-14

    The piezoelectric compositions (1 − x)Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–x(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} (BZT-xBCT) span a model lead-free morphotropic phase boundary (MPB) between room temperature rhombohedral and tetragonal phases at approximately x = 0.5. In the present work, in situ X-ray diffraction measurements during electric field application are used to elucidate the origin of electromechanical strain in several compositions spanning the tetragonal compositional range 0.6 ≤ x ≤ 0.9. As BCT concentration decreases towards the MPB, the tetragonal distortion (given by c/a-1) decreases concomitantly with an increase in 90° domain wall motion. The increase in observed macroscopic strain is predominantly attributed to the increased contribution from 90° domain wall motion. The results demonstrate that domain wall motion is a significant factor in achieving high strain and piezoelectric coefficients in lead-free polycrystalline piezoelectrics.

  14. INTERVIU CU DOAMNA SIMONA CAROBENE, ADMINISTRATORUL SC PROIECT MOZAIC SRL

    Directory of Open Access Journals (Sweden)

    Gheorghe Pascaru

    2013-12-01

    Full Text Available Fabrica de mozaic, înregistrată la Oficiul Registrului Comerţului în aprilie 2012 a luat fiinţă în cadrul unui proiect cu finanţare europeană nerambursabilă și are în prezent statutul de unitate protejată autorizată. În cadrul acesteia sunt angajați 10 tineri post instituţionalizați, pentru care integrarea în viaţa socială şi profesională este dificilă. Întreprinderea socială SC Proiect Mozaic SRL este rezultatul întâlnirii dintre sectorul social, non-profit şi sectorul business, deoarece are la bază un parteneriat cu un important grup de firme din domeniul construcţiilor şi amenajărilor interioare din București. În paralel cu activitatea de producţie a mozaicului, ocazional, Proiect Mozaic oferă către clienți și servicii de ambalare și asamblare produse.

  15. Magnesium and cadmium in covalently bonded networks. Synthesis and structure of AETMg and AETCd (AE = Ca, Sr; T = Pd, Ag, Pt, Au) with TiNiSi type structure and the solid solution Yb{sub 2-x}PtMg{sub x}

    Energy Technology Data Exchange (ETDEWEB)

    Kersting, Marcel; Johnscher, Michael; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2013-07-01

    The equiatomic intermetallic compounds AETMg and AETCd (AE = Ca, Sr; T = Pd, Ag, Pt, Au) and the whole solid solution Yb{sub 2-x}PtMg{sub x} were synthesized from the elements in sealed niobium tubes in a high-frequency or a muffle furnace. All samples were characterized on the basis of their powder X-ray diffraction patterns. The structures of SrAuCd, CaPdCd, CaPtCd, CaPdMg, SrPtMg, CaAg{sub 1.017}Mg{sub 0.983}, SrAg{sub 1.032}Mg{sub 0.968}, and Yb{sub 1.792}PtMg{sub 0.208} were refined on the basis of single-crystal X-ray diffractometer data. Some of the crystals showed small homogeneity ranges. All compounds crystallize with the orthorhombic TiNiSi type structure, space group Pnma. The crystal chemistry is briefly discussed and variations in chemical bonding as a result of the electronegativity of the transition metal are described. (orig.)

  16. Separation of cyclotron-produced 44Sc from a natural calcium target using a dipentyl pentylphosphonate functionalized extraction resin

    Science.gov (United States)

    Valdovinos, H.F.; Hernandez, R.; Barnhart, T.E.; Graves, S.; Cai, W.; Nickles, R.J.

    2014-01-01

    Significant interest in 44Sc as a radioactive synthon to label small molecules for positron emission tomography (PET) imaging has been recently observed. Despite the efforts of several research groups, the ideal 44Sc production and separation method remains elusive. Herein, we propose a novel separation method to obtain 44Sc from the proton irradiation of calcium targets based on extraction chromatography, which promises to greatly simplify current production methodologies. Using the commercially available Uranium and Tetravalent Actinides (UTEVA) extraction resin we were able to rapidly ( 80% of the activity generated at end of bombardment (EoB) in small ~1 M HCl fractions (400 μL). The chemical purity of the 44Sc eluates was evaluated through chelation with DOTA and DTPA, and by trace metal analysis using microwave induced plasma atomic emission spectrometry. The distribution coefficients (Kd) of Sc(III) and Ca(II) in UTEVA were determined in HCl medium in a range of concentrations from zero to 12.1 M The 44Sc obtained with our method proved to be suitable for the direct labeling of small biomolecules for PET imaging, with excellent specific activities and radiochemical purity. PMID:25464172

  17. Magnetic and charge ordering properties of Bi{sub 0.2}Ca{sub 0.8}Mn{sub 0.9}X{sub 0.1}O{sub 3} (where X = Ti, Cr, Fe, Co, Ni, Cu)

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Kamlesh [Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Vaithyanathan, V.; Inbanathan, S.S.R. [Post Graduate and Research Department of Physics, The American College, Madurai 625002 (India); Varma, G.D., E-mail: gdvarfph@iitr.ernet.in [Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2012-08-25

    Highlights: Black-Right-Pointing-Pointer Structural, magnetic and transport properties of Bi{sub 0.2}Ca{sub 0.8}Mn{sub 0.9}X{sub 0.1}O{sub 3} (where X = Ti, Cr, Fe, Co, Ni, Cu) have been studied. Black-Right-Pointing-Pointer T{sub CO} decreases by {approx}10 K and {approx}33 K, in Ni{sup 2+} and Cu{sup 2+} doped samples, while it increases by 42 K in Ti{sup 4+} doped sample. Black-Right-Pointing-Pointer In case of Fe{sup 3+}, Co{sup 3+} and Cr{sup 3+} doped samples charge-ordering (CO) completely disappears. Black-Right-Pointing-Pointer Furthermore, the enhancement in resistivity in all the doped samples with respect to undoped one has been observed. Black-Right-Pointing-Pointer The magnetic exchange interactions between Mn and doped ions explain magnetic and electrical properties. - Abstract: Structural, magnetic and transport properties of Bi{sub 0.2}Ca{sub 0.8}Mn{sub 0.9}X{sub 0.1}O{sub 3} (where X = Ti, Cr, Fe, Co, Ni, Cu) have been investigated. The parent sample Bi{sub 0.2}Ca{sub 0.8}MnO{sub 3} (BCMO) exhibits robust charge-ordered antiferrromagnetic (COAFM) phase with charge ordering temperature (T{sub CO}) {approx}155 K and AFM Neel temperature (T{sub N}) {approx}105 K. T{sub CO} decreases by {approx}10 K and {approx}33 K, respectively, in Ni{sup 2+} and Cu{sup 2+} doped samples, while it increases by 42 K in Ti{sup 4+} doped sample. In case of Fe{sup 3+}, Co{sup 3+} and Cr{sup 3+} doped samples charge-ordering (CO) completely melts. The paramagnetic (PM) to ferromagnetic (FM) transition temperatures (T{sub C}) of doped samples have lower values as compared to undoped one. In addition, a spin glass (SG) state is observed in all the samples and the magnetic state at T < T{sub C} is akin to a cluster glass (CG) for undoped and Ni, Cu, Ti doped samples formed due to the presence of FM clusters in COAFM matrix. Furthermore, the enhancement in resistivity in all the doped samples with respect to undoped one has been observed. Based on the present study it has

  18. Electronic structure and physical properties of ScN in pressure: density-functional theory calculations

    Institute of Scientific and Technical Information of China (English)

    Guan Peng-Fei; Wang Chong-Yu; Yu Tao

    2008-01-01

    Local density functional is investigated by using the full-potential linearized augmented plane wave (FP-LAPW) method for ScN in the hexagonal structure and the rocksalt structure and for hexagonal structures linking a layered hexagonal phase with wurtzite structure along a homogeneous strain transition path. It is found that the wurtzite ScN is unstable and the layered hexagonal phase, labelled as ho, in which atoms are approximately fivefold coordinated,is metastable, and the rocksalt ScN is stable. The electronic structure, the physical properties of the intermediate structures and the energy band structure along the transition are presented. It is found that the band gaps change from 4.0 to 1.0eV continuously when c/a value varies from 1.68 to 1.26. It is noticeable that the study of ScN provides an opportunity to apply this kind of material (in wurtzite[h]-derived phase).

  19. Midbrain dopamine neurons bidirectionally regulate CA3-CA1 synaptic drive.

    Science.gov (United States)

    Rosen, Zev B; Cheung, Stephanie; Siegelbaum, Steven A

    2015-12-01

    Dopamine (DA) is required for hippocampal-dependent memory and long-term potentiation (LTP) at CA1 Schaffer collateral (SC) synapses. It is therefore surprising that exogenously applied DA has little effect on SC synapses, but suppresses CA1 perforant path (PP) inputs. To examine DA actions under more physiological conditions, we used optogenetics to release DA from ventral tegmental area inputs to hippocampus. Unlike exogenous DA application, optogenetic release of DA caused a bidirectional, activity-dependent modulation of SC synapses, with no effect on PP inputs. Low levels of DA release, simulating tonic DA neuron firing, depressed the SC response through a D4 receptor-dependent enhancement of feedforward inhibition mediated by parvalbumin-expressing interneurons. Higher levels of DA release, simulating phasic firing, increased SC responses through a D1 receptor-dependent enhancement of excitatory transmission. Thus, tonic-phasic transitions in DA neuron firing in response to motivational demands may cause a modulatory switch from inhibition to enhancement of hippocampal information flow.

  20. Diagramas de equilibrio cuaternarios ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2). Una poderosa herramienta para el desarrollo de nuevos materiales por sinterización reactiva

    OpenAIRE

    Moya, J. S.; Bartolomé, J. F.; Peña, P.

    2011-01-01

    En este articulo se exponen, discuten y evalúan los trabajos que sobre materiales de Mullita-Circona obtenidos por sinterización reactiva dirigió e inspiro Salvador de Aza sobre la base de los diagramas de equilibrio de fase multicomponentes ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2). Se analiza su impacto en distintas áreas de la ciencia y tecnología cerámicas tales como chamotas refractarias, industria del aluminio, etc. También se proponen posibles campos de aplicación futura como es el ...

  1. The temporoammonic input to the hippocampal CA1 region displays distinctly different synaptic plasticity compared to the Schaffer collateral input in vivo: significance for synaptic information processing

    Directory of Open Access Journals (Sweden)

    Ayla eAksoy Aksel

    2013-08-01

    Full Text Available In terms of its sub-regional differentiation, the hippocampal CA1 region receives cortical information directly via the perforant (temporoammonic path (pp-CA1 synapse and indirectly via the tri-synaptic pathway where the last relay station is the Schaffer collateral-CA1 synapse (Sc-CA1 synapse. Research to date on pp-CA1 synapses has been conducted predominantly in vitro and never in awake animals, but these studies hint that information processing at this synapse might be distinct to processing at the Sc-CA1 synapse. Here, we characterized synaptic properties and synaptic plasticity at the pp-CA1 synapse of freely behaving adult rats. We established that field excitatory postsynaptic potentials at the pp-CA1 have longer onset latencies and a shorter time-to-peak compared to the Sc-CA1 synapse. LTP (> 24h was successfully evoked by tetanic afferent stimulation of pp-CA1 synapses. Low frequency stimulation evoked synaptic depression at Sc-CA1 synapses, but did not elicit LTD at pp-CA1 synapses unless the Schaffer collateral afferents to the CA1 region had been severed. Paired-pulse responses also showed significant differences. Our data suggest that synaptic plasticity at the pp-CA1 synapse is distinct from the Sc-CA1 synapse and that this may reflect its specific role in hippocampal information processing.

  2. The temporoammonic input to the hippocampal CA1 region displays distinctly different synaptic plasticity compared to the Schaffer collateral input in vivo: significance for synaptic information processing

    Science.gov (United States)

    Aksoy-Aksel, Ayla; Manahan-Vaughan, Denise

    2013-01-01

    In terms of its sub-regional differentiation, the hippocampal CA1 region receives cortical information directly via the perforant (temporoammonic) path (pp-CA1 synapse) and indirectly via the tri-synaptic pathway where the last relay station is the Schaffer collateral-CA1 synapse (Sc-CA1 synapse). Research to date on pp-CA1 synapses has been conducted predominantly in vitro and never in awake animals, but these studies hint that information processing at this synapse might be distinct to processing at the Sc-CA1 synapse. Here, we characterized synaptic properties and synaptic plasticity at the pp-CA1 synapse of freely behaving adult rats. We observed that field excitatory postsynaptic potentials at the pp-CA1 synapse have longer onset latencies and a shorter time-to-peak compared to the Sc-CA1 synapse. LTP (>24 h) was successfully evoked by tetanic afferent stimulation of pp-CA1 synapses. Low frequency stimulation evoked synaptic depression at Sc-CA1 synapses, but did not elicit LTD at pp-CA1 synapses unless the Schaffer collateral afferents to the CA1 region had been severed. Paired-pulse responses also showed significant differences. Our data suggest that synaptic plasticity at the pp-CA1 synapse is distinct from the Sc-CA1 synapse and that this may reflect its specific role in hippocampal information processing. PMID:23986697

  3. ViSC Social Competence Program.

    Science.gov (United States)

    Strohmeier, Dagmar; Hoffmann, Christine; Schiller, Eva-Maria; Stefanek, Elisabeth; Spiel, Christiane

    2012-01-01

    The ViSC Social Competence Program has been implemented in Austrian schools within the scope of a national strategy plan, Together Against Violence. The program is a primary preventive program designed for grades 5 to 8. The prevention of aggression and bullying is defined as a school development task, and the initial implementation of the program lasts one school year. The program consists of universal and specific actions that are implemented through in-school teacher training and a class project for students. The program was evaluated with a randomized intervention control group design. Data were collected from teachers and students. Results suggest that the program reduces aggression in schools.

  4. BOOK REVIEW: Assessing Sc1 for GCSE

    Science.gov (United States)

    Reynolds, H.

    2000-01-01

    It is well known that investigations that `fit' the National Curriculum or examination board criteria are few in number. The fair testing emphasis means that pupils all over the country are finding out what affects the rate of a chemical reaction, the rate of photosynthesis or, in the case of Physics, the resistance of a wire. This book focuses on nine of the most common Sc1 investigations and how to prepare for them, manage and assess them. The author, a GCSE examiner, has turned his expertise into a handbook for improving Sc1 performance in the classroom. He has produced a book that would be extremely useful to both newly qualified teachers and experienced teachers. The first aim of the book, however, is to explain the requirements of Sc1. This is done comprehensively with examples of what the jargon means in practice. By breaking down the elements of planning, obtaining evidence, analysing evidence and evaluating, it is easy to see the subtleties of the mark descriptors. At first glance there seems to be little difference between the type of scientific knowledge needed for planning at level 6 and level 8. However, the level 8 statement specifies `detailed' scientific knowledge and understanding, which would mean a student should use equations from physics or symbolic chemical equations to support their arguments. One of the most useful sections in the book details the marking problems that can arise with some investigations. For example, in an investigation into electromagnets it is difficult for students to provide sufficient relevant scientific theory to satisfy the requirements of planning at level 6. One of the problems with Sc1 is that certain requirements, such as graph plotting, are difficult for many students. This book provides exercises that can be given to students to improve those skills. Each of the nine investigations is covered in great detail. Each investigation begins with an introduction detailing the rationale for choosing it, whether students

  5. Construction of multiform scFv antibodies using linker peptide

    Institute of Scientific and Technical Information of China (English)

    Shihua Wang; Cengjie Zheng; Ying Liu; Huirong Zheng; Zonghua Wang

    2008-01-01

    Multiform single chain variable fragments (acFvs) including different length linker scFvs and bispecific seFv were constructed. The linker lengths of 0, 3, 5, 8, 12, and 15 amino acids between VH and VL of antideoxynivalenol (anti-DON) scFv were used to analyze the affinities of scFvs. The affinity constants of these scFvs increased when the linker was lower than 12 amino acids. The affinity constant would not change when the linker was longer than 12 amino acids. Fusion gene of anti-DON seFv and antizearalenone (anti-ZEN) scFv was also constructed through eormection by a short peptide tinker DNA to express a bispecific scFv. The affinity constants assay showed that the two scFvs of fusion bispecific scFv remained their own affinity compared to their parental scFvs. Competitive direct enzyme linked immunosorbent assay was used to detect DON and ZEN in contaminated wheat (Triticum aestivum L.) samples, and the results indicated that this bispecifie acFv was applicable in DON and ZEN detection. This work confirmed that bispecific scFv could be successfully obtained, and might also have an application in diagnosing fungal infection, and breeding transgertic plants.

  6. Domain structure and phase transition in Sc-doped zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Brunauer, G.; Boysen, H.; Frey, F. [Institute for Crystallography und Applied Mineralogy, LMU Muenchen, Munich (Germany); Ehrenberg, H. [Institute for Materials Science, TU Darmstadt, Darmstadt (Germany)

    2002-01-21

    The temperature dependence of the domain structure associated with the ferroelastic phase transition (Fm{sup 3-bar}m{r_reversible}R{sup 3-bar}m) in ZrO{sub 2} doped with 11% Sc{sub 2}O{sub 3} has been determined from a peak shape analysis of high-resolution synchrotron x-ray powder diffraction data. In the temperature region of coexisting phases the observed characteristic anisotropic broadening and asymmetry of the lines is modelled by three different phases: a main rhombohedral phase, a distorted rhombohedral phase with a smaller c/a ratio, and a cubic phase. The latter two are assigned to the internal structure of the domain walls between two adjacent twin domains. The size and amount of the cubic phase show an initially slow increase with temperature followed by a very steep increase and a slow one after that. The size of the (main) rhombohedral domains remains nearly constant, while (micro-) strain in the distorted regions gradually decreases. (author)

  7. Producción y caracterización de nuevos materiales multiferróicos basados en el sistema LCMO/BLZT Ba0.9La0.067Ti0.91Zr0.09O3 / La0.67Ca0.33MnO3

    Directory of Open Access Journals (Sweden)

    Jorge Andrés Cardona Vásquez

    2012-07-01

    Full Text Available We report the details of synthesis and structural, electrical and magnetic characterization of Ba0.9La0.067Ti0.91Zr0.09O3 /La0.67Ca0.33MnO3 multiferroic system. Were prepared by the solid state reaction technique, mixtures with different percentages of the mass of lanthanum calcium manganite La0.67Ca0.33MnO3 (LCMO in its ferromagnetic phase, and barium-lanthanumzirconatetitanate, Ba0.9La0.067Ti0.91Zr0.09O3 (BLZT which has been reported as ferroelectric. Patterns of X-ray diffraction showed that the materials have reacted resulting in new materials perovskite like structure with P4mm (# 99 tetragonal symmetry space group. The structure of the material was refined using the Rietveld method. FC and ZFC magnetization curves show two phase transitions, one of them above 200 K and the other below 50 K, such transitions has been associated with two different magnetic regimes. Hysteresis curves measured confirm that the relationship between the applied field and the magnetization does not have a linear behavior. Impedance spectroscopy measurements show a ferroelectric character with dielectric loss, this behavior is confirmed by polarization curves performed in the synthesized materials.

  8. Novel permeability characteristics of red blood cells from sickle cell patients heterozygous for HbS and HbC (HbSC genotype).

    Science.gov (United States)

    Dalibalta, S; Ellory, J C; Browning, J A; Wilkins, R J; Rees, D C; Gibson, J S

    2010-06-15

    Individuals heterozygous for HbS and HbC (HbSC) represent about 1/3(rd) of sickle cell disease (SCD) patients. Whilst HbSC disease is generally milder, there is considerable overlap in symptoms with HbSS disease. HbSC patients, as well as HbSS ones, present with the chronic anaemia and panoply of acute vaso-occlusive complications that characterize SCD. However, there are important clinical and haematological differences. Certain complications occur with greater frequency in HbSC patients (like proliferative retinopathy and osteonecrosis) whilst intravascular haemolysis is reduced. Patients with HbSC disease can be considered as a discrete subset of SCD cases. Although much work has been carried out on understanding the pathogenesis of SCD in HbSS homozygotes, including the contribution of altered red blood cell permeability, relatively little pertains directly to HbSC individuals. Results reported in the literature suggest that HbSC cells, and particularly certain subpopulations, present with similar permeability to HbSS cells but there are also important differences - these have not been well characterized. We hypothesise that their unique cell transport properties accounts for the different pattern of disease in HbSC patients and represents a potential chemotherapeutic target not shared in red blood cells from HbSS patients. The distinct pattern of clinical haematology in HbSC disease is emphasised here. We analyse some of the electrophysiological properties of single red blood cells from HbSC patients, comparing them with those from HbSS patients and normal HbAA individuals. We also use the isosmotic haemolysis technique to investigate the behaviour of total red blood cell populations. Whilst both HbSS and HbSC cells show increased monovalent and divalent (Ca(2+)) cation conductance further elevated upon deoxygenation, the distribution of current magnitudes differs, and outward rectification is greatest for HbSC cells. In addition, although Gd(3+) largely

  9. Development of bonding techniques for cryogenic components (2). HIP bonding between Cu Alloys and Ti, cryogenic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Shigeru; Ouchi, Nobuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Fukaya, Kiyoshi [Nihon Advanced Technology Ltd., Tokai, Ibaraki (Japan); Ishiyama, Shintaro [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Tsuchiya, Yoshinori; Nakajima, Hideo [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    2003-03-01

    Several joints between dissimilar materials are required in the superconducting (SC) magnet system of SC linear accelerator or fusion reactor, Pure titanium (Ti) is one of candidate materials for a jacket of SC coil of fusion reactor because Ti is non-magnetic material and has a feature that its thermal expansion is similar to SC material in addition to good corrosion resistance and workability. Also, Ti does not require strict control of environment during reaction heat treatment of SC material. Copper (Cu) or Cu-alloy is used in electrical joints and cryogenic stainless steel (SS) is used in cryogenic pipes. Therefore, it is necessary to develop new bonding techniques for joints between Ti, Cu, and SS because jacket, electrical joint and cryogenic pipe have to be bonded each other to cool SC coils. Japan Atomic Energy Research Institute (JAERI) has started to develop dissimilar material joints bonded by hot isostatic pressing (HIP), which can bring a high strength joint with good tolerance and can applied to a large or complex geometry device. HIP conditions for Cu-Ti, Cu alloy-Ti, Cu alloy-SS were investigated in this study and most stable HIP condition were evaluated by microscopic observation, tensile and bending tests at room temperature. (author)

  10. 具有高电荷分离效率和光催化活性的锆掺杂钛酸钙的制备%Preparation of Zr-doped CaTiO3 with enhanced charge separation efficiency and photocatalytic activity

    Institute of Scientific and Technical Information of China (English)

    黄晓俊; 严欣; 吴海燕; 方莹; 闵亚红; 李文生; 王双印; 吴振军

    2016-01-01

    A series of Zr-doped CaTiO3 powders were prepared with the mild co-precipitation method and calcined at 850 °C for 3 h. The as-prepared Zr-doped CaTiO3 samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV−Vis diffuse reflectance spectra (DRS) and X-ray photoelectron spectra (XPS). XRD result revealed the presence of single perovskite phase of CaTiO3. UV−Vis diffusive reflection spectra of Zr-doped CaTiO3 indicated that the absorbance obviously increased in the visible light irradiation. XPS analysis showed that two types of oxygen existed on the photocatalyst surface, including lattice oxygen and absorbed oxygen. Their photocatalytic activity in the case of the degradation of methyl orange in water and photoelectrochemical activity were also tested. The 5%Zr-doped (mole fraction) CaTiO3 sample showed the highest photocatalytic activity. The enhanced photocatalytic activity was ascribed to the change of the lattice structure, existence of oxygen vacancies and increase of the photogenerated charge separation efficiency.%通过温和共沉淀方法合成一系列锆掺杂的钛酸钙,并在850°C下焙烧3 h。采用扫描电镜(SEM)、X射线衍射(XRD)、紫外−可见漫反射光谱(DRS)和X射线光电子能谱(XPS)等手段对合成的锆掺杂的钛酸钙进行表征。XRD结果表明,锆掺杂钛酸钙以单一的钙钛矿相存在;紫外−可见漫反射光谱分析表明,锆掺杂钛酸钙在可见光区的吸收明显增强;XPS分析显示,在光催化剂表面存在2种类型的氧,即晶格氧和吸附氧。此外,对其光催化降解甲基橙的性能以及光电化学性能进行测试。结果表明,5% Zr(摩尔分数)掺杂钛酸钙具有最高光催化活性。晶格结构的改变、氧空穴的存在、光生电荷分离效率的提高都有利于提高锆掺杂的钛酸钙的光催化活性。

  11. Bioactivity studies on TiO{sub 2}-bearing Na{sub 2}O–CaO–SiO{sub 2}–B{sub 2}O{sub 3} glasses

    Energy Technology Data Exchange (ETDEWEB)

    Jagan Mohini, G. [Department of Physics, Andhra Loyola College, Vijayawada 520 008, Andhra Pradesh (India); Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar 522 510, A.P. (India); Sahaya Baskaran, G. [Department of Physics, Andhra Loyola College, Vijayawada 520 008, Andhra Pradesh (India); Ravi Kumar, V. [Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar 522 510, A.P. (India); Piasecki, M. [Institute of Physics, J. Dlugosz University, Al. Armii Krajowej 13/15, Czestochowa (Poland); Veeraiah, N., E-mail: nvr8@rediffmail.com [Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar 522 510, A.P. (India)

    2015-12-01

    Soda lime silica borate glasses mixed with different concentrations of TiO{sub 2} are synthesized by the melt-quenching technique. As a part of study on bioactivity of these glasses, the samples were immersed in simulated body fluid (SBF) solution for prolonged times (~ 21 days) during which weight loss along with pH measurements is carried out at specific intervals of time. The XRD and SEM analyses of post-immersed samples confirm the formation of crystalline hydroxyapatite layer (HA) on the surface of the samples. To assess the role of TiO{sub 2} on the formation of HA layer and degradability of the samples the spectroscopic studies viz. optical absorption and IR spectral studies on post- and pre-immersed samples have been carried out. The analysis of the results of degradability together with spectroscopic studies as a function of TiO{sub 2} concentration indicated that about 6.0 mol% of TiO{sub 2} is the optimal concentration for achieving better bioactivity of these glasses. The presence of the maximal concentration octahedral titanium ions in this glass that facilitates the formation of HA layer is found to be the reason for such a higher bioactivity. - Highlights: • Soda lime silica borate glasses mixed with TiO{sub 2} are synthesized. • Bioactivity of the glasses is studied by immersing them in SBF solution. • XRD and SEM studies indicated the formation of hydroxyapatite layer on the surface. • Quantum of degradability is the highest in the glasses mixed with 6.0 mol% of TiO{sub 2.} • The results are analyzed using IR and optical absorption studies.

  12. SC response characteristics of two kinds of coagulant

    Institute of Scientific and Technical Information of China (English)

    杨万东; 宋爽; 史惠祥

    2002-01-01

    Automatic coagulant dosage control with streaming current (SC) technique is introduced in this paper. Aluminum and ferric coagulants are widely used in surface water treatment. The SC response characteristics of P-AlCl3 aluminum coagulant and P-FeCl3 ferric coagulant were investigated in this work. Bench-scale water treatment results were obtained from jar tests including rapid mixing, flocculation and undisturbed sedimentation. Results showed that aluminum coagulant is more sensitive than ferric coagulant to SC response.

  13. SC response characteristics of two kinds of coagulant

    Institute of Scientific and Technical Information of China (English)

    杨万东; 宋爽; 史惠祥

    2002-01-01

    Automatic coagulant dosage control with streaming current (SC) technique is in troduced inthis paper. Aluminum and ferric coagulants are widely used in surface water treatment. The SC response characteristics of P-AiCI3 aluminum coagulant and P-FeCI3 ferric coagulant were investigated in this work. Bench-scale water treatment results were obtained from jar tests including rapid mixing,flocculation and undisturbed sedimentation. Results showed that aluminum coagulant is more sensitive than ferric coagulant to SC response.

  14. Large electrostrictive effect and bright upconversion luminescence in Er-modified 0.92(Bi{sub 0.5}Na{sub 0.5})TiO{sub 3}–0.08(Ba{sub 0.90}Ca{sub 0.10})(Ti{sub 0.92}Sn{sub 0.08})O{sub 3} lead-free ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoli; Wu, Meihua; Diao, Wenxin; Zhang, Bing; Hao, Jigong, E-mail: haojigong@lcu.edu.cn; Xu, Zhijun; Chu, Ruiqing

    2015-10-01

    In this study, a new lead-free luminescent electrostrictive material has been obtained by introducing trivalent Er{sup 3+} as the activator into 0.92(Bi{sub 0.5}Na{sub 0.5})TiO{sub 3}–0.08(Ba{sub 0.90}Ca{sub 0.10})(Ti{sub 0.92}Sn{sub 0.08})O{sub 3} (BNT–0.08BCST). A high, purely electrostrictive effect (the electrostrictive coefficient Q{sub 33} reaches up to 0.028 m{sup 4}/C{sup 2}) with exceptionally good fatigue resistance (up to 10{sup 6} cycles) and thermostability (25–140 °C) is obtained in 0.2 mol%Er-modified BNT–0.08BCST ceramics. Besides the excellent electrostrictive properties, Er{sup 3+}-modified BNT–0.08BCST samples exhibit a strong green-red upconversion emission, and the emission intensities are strongly dependent on the doping concentration, which reaches the optimal value as the doping concentration is 0.4 mol%. These results suggest that this kind of material may have potential application as a multifunctional device by integrating its excellent upconversion luminescence and electrostrictive properties.

  15. Anomalous Halo Formation in an Arc-Melted ScNi-Sc2Ni Off-Eutectic Binary Alloy

    Directory of Open Access Journals (Sweden)

    Kai Wang

    2016-07-01

    Full Text Available Diverse non-equilibrium eutectic structures have attracted numerous experimental and theoretical studies. One special type is the formation of a halo of one phase around a primary dendrite of another phase. In our experiments, it was occasionally observed that ScNi halos grow as dendritic morphology around the primary Sc 2 Ni dendrites in an arc-melted ScNi-Sc 2 Ni off-eutectic binary alloy. The formation of this anomalous halo structure was then well reproduced by employing quantitative phase-field simulations. Based on the phase-field simulation, It was found that (i the large undercooling and growth velocity of the ScNi phase during solidification causes the formation of halos; and (ii the released latent heat induces the recalescence phenomenon, and changes the solidification sequence largely, resulting in the anomalous halo structure in the Sc-34 at % Ni alloy.

  16. Exploration of R2XM2 (R=Sc, Y, Ti, Zr, Hf, rare earth; X=main group element; M=transition metal, Si, Ge): Structural Motifs, the novel Compound Gd2AlGe2 and Analysis of the U3Si2 and Zr3Al2 Structure Types

    Energy Technology Data Exchange (ETDEWEB)

    McWhorter, Sean William [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    In the process of exploring and understanding the influence of crystal structure on the system of compounds with the composition Gd5(SixGe1-x)4 several new compounds were synthesized with different crystal structures, but similar structural features. In Gd5(SixGe1-x)4, the main feature of interest is the magnetocaloric effect (MCE), which allows the material to be useful in magnetic refrigeration applications. The MCE is based on the magnetic interactions of the Gd atoms in the crystal structure, which varies with x (the amount of Si in the compound). The crystal structure of Gd5(SixGe1-x)4 can be thought of as being formed from two 32434 nets of Gd atoms, with additional Gd atoms in the cubic voids and Si/Ge atoms in the trigonal prismatic voids. Attempts were made to substitute nonmagnetic atoms for magnetic Gd using In, Mg and Al. Gd2MgGe2 and Gd2InGe2 both possess the same 32434 nets of Gd atoms as Gd5(SixGe1-x)4, but these nets are connected differently, forming the Mo2FeB2 crystal structure. A search of the literature revealed that compounds with the composition R2XM2 (R=Sc, Y, Ti, Zr, Hf, rare earth; X=main group element; M=transition metal, Si, Ge) crystallize in one of four crystal structures: the Mo2FeB2, Zr3Al2, Mn2AlB2 and W2CoB2 crystal structures. These crystal structures are described, and the relationships between them are highlighted. Gd2AlGe2 forms an entirely new crystal structure, and the details of its synthesis and characterization are given. Electronic structure calculations are performed to understand the nature of bonding in this compound and how

  17. Energy dependence of deformation parameters in the SC(p,p') SC reaction

    Energy Technology Data Exchange (ETDEWEB)

    Jones, K.W.; Glashausser, C.; de Swiniarski, R.; Nanda, S.; Carey, T.A.; Cornelius, W.; Moss, J.M.; McClelland, J.B.; Comfort, J.R.; Escudie, J.

    1986-01-01

    Values of deformation parameters have been extracted from macroscopic coupled-channels analyses of inelastic proton scattering to the first 2 , 3 , and 4 states of SC over the energy range from 200 to 700 MeV. The apparent deformations are almost unchanged over this energy interval; they agree also with nucleon scattering data at much lower energies and at 800 MeV and 1 GeV.

  18. IEC SC15E: Report on liaison activities of CIGRÉ-SC15

    DEFF Research Database (Denmark)

    Henriksen, Mogens

    2000-01-01

    WG’s activities under CIGRÉ SC15:WG 15.01 - Fluid impregnated systems.WG 15.02 - Dielectric Liquids.WG 15.03 - Gas Insulation.WG 15.04 - Outdoor Insulation.WG 15.05 - Capacitors.WG 15.07 - Solid Insulating Materials for Rotating Machines.WG 15/33.08 - Insulation Monitoring and Life Estimation. WG...

  19. Observation of subsonic and supersonic radiation fronts on OMEGA utilizing radiation transport through Sc-doped aerogels

    Science.gov (United States)

    Johns, H. M.; Kline, J.; Lanier, N.; Perry, T.; Fontes, C.; Fryer, C.; Brown, C.; Morton, J.; Hager, J.

    2016-10-01

    The propagation of a heat front in an astrophysical or inertial confinement fusion plasma involves both the equation of state and the opacity of the plasma, and is therefore an important and challenging radiation transport problem. Past experiments have used absorption spectroscopy in chlorinated foams to measure the heat front. (D. Hoarty et al. PRL 82, 3070, 1999). Recent development of Ti-doped cylindrical aerogel foam targets (J. Hager et al. submitted to RSI) results in a more suitable platform for higher temperatures on NIF than Cl dopant. Ti K-shell absorption spectra can be modeled with PrismSPECT to obtain spatially resolved temperature profiles between 100-180eV. Sc dopant has been selected to characterize the heat front between 60-100eV. Improved understanding of non-planckian x-ray drives generated by hohlraums will advance characterization of the radiation transport. Prior work demonstrates PrismSPECT with OPLIB is more physically complete for Sc (H. Johns et al. submitted to RSI). We will present the first application of spectroscopic analysis of the Sc-doped aerogels utilizing this method. This work performed under the auspices of the U.S. Department of Energy by LANL under contract DE-AC52-06NA25396.

  20. Genetic and physical fine-mapping of the Sc locus conferring indica-japonica hybrid sterility in rice (Oryza sativa L.)

    Institute of Scientific and Technical Information of China (English)

    YANG Cunyi; CHEN Zhongzheng; ZHUANG Chuxiong; MEI Mantong; LIU Yaoguang

    2004-01-01

    Hybrid sterility is a major hindrance to utilizing the heterosis in indica-japonica hybrids. To isolate a gene Sc conferring the hybrid sterility, the locus was mapped using molecular markers and an F2 population derived from a cross between near isogenic lines. A primary linkage analysis showed that Sc was linked closely with 4 markers on chromosome 3, on which the genetic distance between a marker RG227 and Sc was 0.07 cM. Chromosome walking with a rice TAC genomic library was carried out using RG227 as a starting probe, and a contig of ca. 320 kb covering the Sc locus was constructed. Two TAC clones, M45E14 and M90J01 that might cover the Sc locus, were partially sequenced. By searching the rice sequence databases with sequences of the TACs and RG227 a japonica rice BAC sequence, OSJNBb0078P24 was identified. By comparing the TAC and BAC sequences, six new PCR-based markers were developed. With these markers the Sc locus was further mapped to a region of 46 kb. The results suggest that the BAC OSJNBb0078P24 and TAC M45E14 contain the Sc gene. Six ORFs were predicted in the focused 46-kb region.

  1. 76 FR 58401 - Safety Zone; Swim Around Charleston, Charleston, SC

    Science.gov (United States)

    2011-09-21

    ... Zone; Swim Around Charleston, Charleston, SC in the Federal Register (76 FR 38586). We received no... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Swim Around Charleston, Charleston, SC... temporary moving safety zone during the Swim Around Charleston, a swimming race occurring on waters of...

  2. Human bulbar conjunctival hemodynamics in hemoglobin SS and SC disease.

    Science.gov (United States)

    Wanek, Justin; Gaynes, Bruce; Lim, Jennifer I; Molokie, Robert; Shahidi, Mahnaz

    2013-08-01

    The known biophysical variations of hemoglobin (Hb) S and Hb C may result in hemodynamic differences between subjects with SS and SC disease. The purpose of this study was to measure and compare conjunctival hemodynamics between subjects with Hb SS and SC hemoglobinopathies. Image sequences of the conjunctival microcirculation were acquired in 9 healthy control subjects (Hb AA), 24 subjects with SC disease, and 18 subjects with SS disease, using a prototype imaging system. Diameter (D) and blood velocity (V) measurements were obtained in multiple venules of each subject. Data were categorized according to venule caliber by averaging V and D for venules with diameters less than (vessel size 1) or greater than (vessel size 2) 15 µm. V in vessel size 2 was significantly greater than V in vessel size 1 in the AA and SS groups (P ≥ 0.009), but not in the SC group (P = 0.1). V was significantly lower in the SC group as compared to the SS group (P = 0.03). In AA and SS groups, V correlated with D (P ≤ 0.005), but the correlation was not statistically significant in the SC group (P = 0.08). V was inversely correlated with hematocrit in the SS group for large vessels (P = 0.03); however, no significant correlation was found in the SC group (P ≥ 0.2). Quantitative assessment of conjunctival microvascular hemodynamics in SS and SC disease may advance understanding of sickle cell disease pathophysiology and thereby improve therapeutic interventions.

  3. Influences of Sr-Incorporated TiO2 Layer on the Photovoltaic Properties of Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Kim, Eun Seong; Kim, Dae-Hwan; Lee, Sang-Ju; Han, Yoon Soo

    2016-03-01

    Effects of a mixed overlayer composed of TiO2 and TiSrO3 on the performance of dye-sensitized solar cells (DSSCs) were investigated. The surface of TiO2 photoelectrode formed on F-doped SnO2 (FTO) was modified by soaking it in a TiCl4:SrCl2 mixed aqueous solution with various molar ratios and then calcining to produce the TiCl4:SrCl2-treated TiO2 photoelectrode (Ti:Sr-TiO2/FTO). The highest power conversion efficiency (PCE) was obtained from DSSC with Ti:Sr(7:3)-TiO2/FTO, which was prepared from the mixed solution with the molar ratio of 7:3 (TiOl4:SrCl2). An enhancement in short-circuit photocurrent (J(sc)) and open-circuit voltage (V(oc)) of DSSC with Ti:Sr(7:3)-TiO2/FTO was achieved, compared to those of the reference device with Ti:Sr(10:0)-TiC2/FTO (i.e., TiO2-coated TiO2/FTO). The incorporation of the mixed overlayer on the nanoporous TiO2 photoelectorde led to an improvement in the electron collection efficiency by a prolonged electron lifetime, thereby increasing the J(sc) value. The increase in V(oc) value of the device with Ti:Sr(7:3)-TiO2/FTO was due to the suppression of the charge recombination between injected electrons and I3(-) ions.

  4. Mass measurement of 56Sc reveals a small A=56 odd-even mass staggering, implying a cooler accreted neutron star crust

    CERN Document Server

    Meisel, Z; Ahn, S; Bazin, D; Brown, B A; Browne, J; Carpino, J F; Chung, H; Cole, A L; Cyburt, R H; Estradé, A; Famiano, M; Gade, A; Langer, C; Matoš, M; Mittig, W; Montes, F; Morrissey, D J; Pereira, J; Schatz, H; Schatz, J; Scott, M; Shapira, D; Smith, K; Stevens, J; Tan, W; Tarasov, O; Towers, S; Wimmer, K; Winkelbauer, J R; Yurkon, J; Zegers, R G T

    2015-01-01

    We present the mass excesses of 52-57Sc, obtained from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. The masses of 56Sc and 57Sc were determined for the first time with atomic mass excesses of -24.85(59)(+0 -54) MeV and -21.0(1.3) MeV, respectively, where the asymmetric uncertainty for 56Sc was included due to possible contamination from a long-lived isomer. The 56Sc mass indicates a small odd-even mass staggering in the A = 56 mass-chain towards the neutron drip line, significantly deviating from trends predicted by the global FRDM mass model and favoring trends predicted by the UNEDF0 and UNEDF1 density functional calculations. Together with new shell-model calculations of the electron-capture strength function of 56Sc, our results strongly reduce uncertainties in model calculations of the heating and cooling at the 56Ti electron-capture layer in the outer crust of accreting neutron stars. We found that, in contrast to prev...

  5. Thermal stability of Al-Mg-Sc-Zr alloy

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wei-tao; YAN De-sheng; RONG Li-jian

    2006-01-01

    The thermal stability of Al3(Sc,Zr) precipitates in the cold worked Al-Mg-Sc-Zr alloy after elevated temperature exposure was investigated. The evaluation was conducted using room temperature tensile, Vicker's hardness, optical metallography and scanning electron microscope (SEM) with the backscatter. The results show that the Al3(Sc,Zr) precipitates and mechanical properties have no obvious change, and the grains keep elongated along the working direction as that in cold worked sample after exposure at 300 ℃ for 1 000 h. The coarsening of Al3(Sc,Zr) precipitates occurs and is no longer effective on the recrystallization resistance, and partial recrystallization is observed after 400 ℃ exposure. In particular, after 500 ℃ exposure, the hardness decreases drastically and the alloy has fully recrystallized due to the obvious coarsening of Al3(Sc,Zr) precipitates.

  6. Hydride vapor phase epitaxy growth of GaN, InGaN, ScN, and ScAIN

    NARCIS (Netherlands)

    Bohnen, T.

    2010-01-01

    Chemical vapor deposition (CVD); hydride vapor phase epitaxy (HVPE); gallium nitride (GaN); indium gallium nitride (InGaN); scandium nitride (ScN); scandium aluminum nitride (ScAlN); semiconductors; thin films; nanowires; III nitrides; crystal growth - We studied the HVPE growth of different III ni

  7. Effective single chain antibody (scFv) concentrations in vivo via adenoviral vector mediated expression of secretory scFv

    NARCIS (Netherlands)

    Arafat, WO; Gomez-Navarro, J; Buchsbaum, DJ; Xiang, J; Casado, E; Barker, SD; Mahasreshti, PJ; Haisma, HJ; Barnes, MN; Siegal, GP; Alvarez, RD; Hemminki, A; Nettelbeck, DM; Curiel, DT

    2002-01-01

    Single chain antibodies (scFv) represent powerful interventional agents for the achievement of targeted therapeutics. The practical utility of these agents have been limited, however, by difficulties related to production of recombinant scFv and the achievement of effective and sustained levels of s

  8. Relationship Between Net Photosynthetic Rate of Cassava SC205 and Its Physio-ecological Factors

    Institute of Scientific and Technical Information of China (English)

    Yong SONG; Xuan LIN; Jinhui YANG; Yuping DENG; Xingyao XIONG

    2014-01-01

    [Objective]The aim was to measure photosynthetic characters of SC 205, a cassava cultivar, and explore the relationships of the net photosynthetic rate (Pn) with physiological and ecological factors. [Method] The diurnal variations of photosyn-thesis in leaves of SC205 were studied by LICOR-6400 portable photosynthesis system, and the relationships of the net photosynthetic rate (Pn) with physiological and ecological factors were studied by simple correlation analysis and path analysis. [Result] The curve of diurnal variation of Pn showed single peak at 10:00 am at 24.07 μ mol CO2 m2/s, without showing midday depression; the diurnal changes of stomatal conductance (Gs), transpiration rate (Tr), leaf temperature (Tl), air tempera-ture (Ta) and photosynthetic active radiation (PAR) al showed single peak curves, and there were positive relationships of Pn with Gs, Tr, Tl, Ta and PAR. The diur-nal variations of intercellular CO2 concentration (Ci), atmospheric CO2 concentration (Ca), relative humidity (RH) showed in a U-shape curve. There were highly signifi-cant positive correlation of Pn with Gs and PAR; the diurnal variation of Pn had highly significant negative correlations with Ci and Ca. The direct impact of physio-logical factors on Pn was as fol ows: Ci>Gs>Tl>Tr, and the direct impact of ecologi-cal factors was RH>PAR>Ca>Ta. [Conclusion] The research showed that Ci, Gs and Tr play very important roles in the changes of Pn among the physiological fac-tors, and PAR and Ca affect the changes of Pn among the ecological factors.

  9. ESTUDO DAS PROPRIEDADES DIELÃTRICAS E ÃPTICAS NA MATRIZ CERÃMICA CaBi4Ti4O15 COM ADIÃÃO DE V2O5/Er2O3/Yb2O3

    OpenAIRE

    MÃcio Costa Campos Filho

    2015-01-01

    Uma forte demanda por materiais mais compactados, de baixo custo e de fÃcil fabricaÃÃo sÃo necessÃrios para diversas aplicaÃÃes tecnolÃgicas, neste sentido diversos materiais cerÃmicos sÃo candidatos por suas propriedades dielÃtricas e Ãpticas. Neste presente trabalho, foram investigadas as propriedades estruturais, dielÃtricas e Ãpticas da fase ortorrÃmbica da matriz cerÃmica ferroelÃtrica CaBi4Ti4O15, uma pseudo-perosviskita de estrutura de camada de bismuto (BLSFs) do grupo espacial A21am ...

  10. Effects of cooling rate on solidification behavior of dilute Al-Sc and Al-Sc-Zr solid solution

    Institute of Scientific and Technical Information of China (English)

    金头男; 聂祚仁; 徐国富; 阮海琼; 杨军军; 付静波; 左铁镛

    2004-01-01

    Six alloys with different compositions of Al-0.1%Sc, Al-0.3%Sc, Al-0.3%Zr, Al-0.1% Sc-0. 1%Zr,Al-0.3%Sc-0.1%Zr and Al-0.3%Sc-0.3%Zr were prepared by casting in a wedge shaped copper mould. The hardness test, microstructure observation, and DSC thermal analysis were applied to fully investigate the solidification behavior of the wedge tip (whose cooling rate is 1 000 K/s) and the top surface (cooling rate 100 K/s) of each casting. The results show that the cast structures in the hypoeutectic region of Al-Sc alloys are slightly affected by cooling rates during the solidification. In the case of hypereutectic alloy of Al-0.3%Sc-0.3%Zr , the cast grains were remarkably refined under the condition of a 100 K/s cooling rate, however, under a 1 000 K/s cooling rate condition,solute atoms contribute nothing to the grain-refinement, due to the eutectic concentration becomes higher. The hardness can be improved to a greater degree by Sc single addition, compared to single Zr addition, but it can be improved even greater when Sc added together with Zr. It is sensitive to cooling rate, the higher the cooling rate, the greater the hardness. By combining the results of TEM