Microstructure and tensile properties of oxide dispersion strengthened Fe–14Cr–0.3Y{sub 2}O{sub 3} and Fe–14Cr–2W–0.3Ti–0.3Y{sub 2}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Auger, M.A., E-mail: mauger@fis.uc3m.es [Departamento de Física, Universidad Carlos III de Madrid, 28911 Leganés (Spain); Castro, V. de; Leguey, T.; Monge, M.A.; Muñoz, A.; Pareja, R. [Departamento de Física, Universidad Carlos III de Madrid, 28911 Leganés (Spain)

2013-11-15

Two ODS ferritic steels with nominal compositions (wt.%): Fe–14Cr–0.3Y{sub 2}O{sub 3} and Fe–14Cr–2W–0.3Ti–0.3Y{sub 2}O{sub 3} have been produced by mechanical alloying and consolidation by hot isostatic pressing. The microstructure and tensile properties of these materials after being forged and heat-treated at 1123 K have been investigated to clarify the interrelation between composition, microstructure and mechanical properties. The second-phase precipitates in these alloys have been analyzed by high-angle annular dark-field imaging in scanning TEM mode and electron diffraction. Fe–14Cr–2W–0.3Ti–0.3Y{sub 2}O{sub 3} exhibits a duplex microstructure consisting of large recrystallized grains, as large as 1.5 μm, and unrecovered regions containing submicron equiaxed grains. In addition, three types of secondary phase particles have been found: large M{sub 23}C{sub 6} particles containing W and Cr, (Cr + Ti) rich spherical particles with diameters between 50 and 500 nm, and fine (Y + Ti) oxide particles with sizes below 30 nm. In contrast, Fe14CrY shows a uniform structure of equiaxed grains, with sizes in the range 0.5–3 μm, containing a fine dispersion of Y oxide particles (<30 nm) homogeneously distributed inside the grains, as well as large carbide and oxide particles. Tensile tests performed over the temperature range 273–973 K have revealed that the alloy containing W and Ti has lower yield and tensile strengths than Fe–14Cr–0.3Y{sub 2}O{sub 3} at temperatures up to 773 K, but the opposite appears to occur beyond this temperature.

Growth of Yb3+-doped Y2O3 single crystal rods by the micro-pulling-down method

International Nuclear Information System (INIS)

Mun, J.H.; Novoselov, A.; Yoshikawa, A.; Boulon, G.; Fukuda, T.

2005-01-01

The rare-earth sesquioxides (RE 2 O 3 , RE = Lu, Y and Sc) are very promising host crystals for advanced laser diode (LD)-pumped Yb 3+ -doped solid-state lasers due to unusual combination, almost unique of favourable structural, thermal and spectroscopic properties which are described. In spite of these favourable properties, the bulk single crystal growth technology for the rare-earth sesquioxides has not been established yet. The extremely high melting temperature at around 2400 deg. C has prevented it. However, we shall show that yttrium oxide crystals (Yb x Y 1-x ) 2 O 3 , x = 0.0, 0.005, 0.05, 0.08 and 0.15 of cylindrical shape as laser rods with 4.2 mm in diameter and 15-20 mm in length have been grown from rhenium crucibles by the micro-pulling-down method. The crystal quality characterisation of undoped Y 2 O 3 crystal was determined using X-ray rocking curve (XRC) analysis. Yb were homogeneously distributed in Y 2 O 3 host crystal

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

International Nuclear Information System (INIS)

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

2016-01-01

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

Effect of alkaline earth oxides on the physical and spectroscopic properties of Dy3+- doped Li2O-B2O3 glasses for white emitting material application

Science.gov (United States)

Shamshad, L.; Rooh, G.; Kirdsiri, K.; Srisittipokakun, N.; Damdee, B.; Kim, H. J.; Kaewkhao, J.

2017-02-01

Li2O-MO-B2O3:0.5Dy2O3 glasses mixed with four different alkaline earth modifier oxides MgO, CaO, SrO and BaO were synthesized by melt quench technique. Their physical properties like density, molar volume and refractive index were measured at room temperature and the effect of alkaline earth modifier oxides were studied. Also, optical absorption and photoluminescence spectra of these glasses have been acquired at room temperature. The Judd-Ofelt theory was effectively used to characterize these spectra and spectral intensities (ƒcal), Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6) and certain radiative properties have been determined. Radiative life-times (τR), branching ratios (βcal), and emission cross-sections (σp) and optical gain parameters (σp × τR) were calculated from the Judd-Ofelt intensity parameters and the variation in these parameters with the variation of glass matrix are discussed. Yellow/Blue (Y/B) ratio and chromacity color coordinates (x,y) are calculated from the emission spectra which indicates the white light generation from all the investigated samples. The correlated color temperature (CCT) for the studied glasses is found to be 4418 K. The fluorescence decay time (τexp) of the 4F9/2 level of Dy3+ has been measured from the decay profiles and compared with calculated lifetimes (τcal). Among all the studied glass matrices, the glass containing BaO exhibits high value of branching ratio, large emission cross-section and high optical gain parameter for 6F9/2 → 6H13 at 575 nm. The results indicates the suitability of all the studied glasses for laser action and white light generation.

Electric and magnetic properties of oxidic titanium bronzes of rare earths Lnsub(2/3+x)TiOsub(3+-y) with perovskite structure

Energy Technology Data Exchange (ETDEWEB)

Bazuev, G V; Makarova, O V; Shvejkin, G P [AN SSSR, Sverdlovsk. Inst. Khimii

1983-01-01

A study was made on electric and magnetic properties of oxidic titanium bronzes of rare earths and their dependence on rare earth nature and the degree of rare earth sublattice filling was followed. Data on Lnsub(2/3)TiOsub(3-y) (Ln-Ce, Nd) anion-deficient perovskites are given as well. Investigated Cesub(2/3)TiOsub(2.985) and Ndsub(2/3)TiOsub(2.875) phases as well as defectless with respect to oxygen Lnsub(2/3)TiOsub(3) phases have rhombic structure of perovskite type with ordered position of Ln/sup 3 +/ cations and vacancies. Specific electric resistance and thermoelectromotive force factor were determined in vacuum at 290-1173 K for samples in the form of parallelepiped of 3x5x25 mm/sup 3/ size. Magnetic susceptibility chi was determined at 77-300 K by Faraday method using a device based on magnetic balance with electromagnetic compensation. Relative error during chi measuring didn't exceed +-2%. Collectivized behaviour of d-electrons of Ti/sup 3 +/ cations in oxidic titanium bronzes of rare earths: Lnsub(2/3+x)TiOsub(3+-y) (Ln-La, Ce, Nd; 0 < x < 1/3), conditioned by formation of narrow, partly filled ..pi..*-zone, was established on the basis of measuring specific electric resistance and magnetic susceptibility.

Creation of Y2Ti2O7 nanoprecipitates to strengthen the Fe-14Cr-3Al-2W steels by adding Ti hydride and Y2O3 nanoparticles

International Nuclear Information System (INIS)

Wang, Linbo; Bai, Zhonglian; Shen, Hailong; Wang, Chenxi; Liu, Tong

2017-01-01

In order to prohibit the formation of large Y-Al-O precipitates, Ti hydride nanoparticles (NPs) were prepared and used to replace Ti as raw particles to fabricate the oxide dispersion strengthened (ODS) Fe-14Cr-3Al-2W-0.35Y 2 O 3 steels by mechanical alloying (MA) and hot isostatic pressing (HIP). As the content of Ti hydride increases from 0.1 to 0.5 and 1.0 wt%, the oxide nanoprecipitates in the ODS steels changes from Y 3 Al 5 O 12 phase to Y 2 Ti 2 O 7 phase (semicoherent with the matrix), and the particle size is successfully reduced. The tensile strength of the ODS steel increases remarkably with increasing Ti hydride content. The sample with 1.0 wt% Ti hydride exhibits a high strength of 1049 MPa at 25 °C and 278 MPa at 700 °C. The creation of Y 2 Ti 2 O 7 nanoprecipitates by adding Ti hydride NPs opens a new way to control the structure and size of the oxide precipitates in the ODS steels. - Graphical abstract: The creation of Y 2 Ti 2 O 7 nanoprecipitates by adding Ti hydride nanoparticles remarkably increases the mechanical properties of the Al-containing ODS steels. - Highlights: •TiH 1.971 reacts with Y 2 O 3 to form Y 2 Ti 2 O 7 in the Al-containing ODS steel. •Addition of TiH 1.971 nanoparticles can prevent the formation of Y-Al-O phases. •Y 2 Ti 2 O 7 nanoparticles share semicoherent interface with the ferrite matrix. •The mean size of oxide dispersion is reduced to 11.2 ± 7.1 nm with 1.0 wt% TiH 1.971 . •The tensile strength of the ODS steel enlarges with increasing TiH 1.971 content.

The selectivity of catalysts composed of V/sub 2/O/sub 5/ supported on ZrO/sub 2/-Y/sub 2/O/sub 3/ mixed oxides for methanol oxidation

International Nuclear Information System (INIS)

VanOmmen, J.G.; Gellings, P.J.; Ross, J.R.H.

1988-01-01

V/sub 2/O/sub 5/ monolayer catalysts were prepared on ZrO/sub 2/ and ZrO/sub 2/ doped with Y/sub 2/O/sub 3/ by two methods. The coverages obtained are only half a monolayer and did not depend on the preparation method or type of support. The selectivity for oxidation of methanol over these V/sub 2/O/sub 5/ catalysts changes from a predominance of formaldehyde to a predominance of methyl formate when the support is doped with Y/sub 2/C/sub 3/, independent of the amount of Y/sub 2/O/sub 3/

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-05-15

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

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

Directory of Open Access Journals (Sweden)

Jianlan Cui

2015-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1980-11-01

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

Research and development of tungsten electrodes added with rare earth oxides

International Nuclear Information System (INIS)

Zuoren Nie; Ying Chen; Meiling Zhou; Tieyong Zuo

2001-01-01

The recent research and development of tungsten electrodes used in TIG and Plasma technologies are introduced, and the tungsten materials as well as the effects of rare earth oxides are specially discussed. in W-La 2 O 3 , W-CeO 2 , W-Y 2 O 3 and W-ThO 2 electrode materials, the W-2.2mass%La 2 O 3 electrode exhibited the best properties when the current is of little or middle volume, and when the electrodes are used in large current, the W-Y 2 O 3 electrode is the best. By a comparative study between the tungsten electrodes activated with single metal oxides, as above-mentioned, and those containing two or three rare earth oxides, namely La 2 O 3 , CeO 2 and Y 2 O 3 , it was indicated that the welding arc properties of the tungsten electrodes activated with combined rare earth oxides additions is superior than that of the electrodes containing single oxides as above mentioned. It was also shown that the operating properties of tungsten electrodes depend intensively on the rare earth oxides contained in the electrodes, and the actions of rare earth oxides during arcing are the most important factors to the electrodes' operating properties, temperature, work function as well as the arc stability. (author)

Electrical properties of the LaLi y Co1 - y O3 - δ (0 ≤ y ≤ 0.10) oxides

Science.gov (United States)

Vecherskii, S. I.; Konopel'ko, M. A.; Batalov, N. N.; Antonov, B. D.; Reznitskikh, O. G.; Yaroslavtseva, T. V.

2017-08-01

The effect of the Li ion concentration on the phase composition, the electrical conductivity, and the thermoelectric power of the LaLi y Co1- y O3-δ (0 ≤ y ≤ 0.1) oxides synthesized by cocrystallization has been studied. It is found that the region of the perovskite-like solid solution LaLi y Co1- y O3-δ is no higher than y = 0.037. In the temperature range 300-1020 K, lithium alloying leads to an increase in the electrical conductivity and a decrease in the positive thermoelectric power of the single-phase samples compared to LaCoO3-δ. The results are discussed using the density of states model proposed by Senarus Rodriguez and Goodenough for LaCoO3-δ and La1- x Sr x CoO3-δ and using the Mott theory of noncrystalline substances.

Generation of H2 and CO by solar thermochemical splitting of H2O and CO2 by employing metal oxides

International Nuclear Information System (INIS)

Rao, C.N.R.; Dey, Sunita

2016-01-01

Generation of H 2 and CO by splitting H 2 O and CO 2 respectively constitutes an important aspect of the present-day concerns with energy and environment. The solar thermochemical route making use of metal oxides is a viable means of accomplishing these reduction reactions. The method essentially involves reducing a metal oxide by heating and passing H 2 O or CO 2 over the nonstoichiometric oxide to cause reverse oxidation by abstracting oxygen from H 2 O or CO 2 . While ceria, perovskites and other oxides have been investigated for this purpose, recent studies have demonstrated the superior performance of perovskites of the type Ln 1−x A x Mn 1−y M y O 3 (Ln=rare earth, A=alkaline earth, M=various +2 and +3 metal ions), in the thermochemical generation of H 2 and CO. We present the important results obtained hitherto to point out how the alkaine earth and the Ln ions, specially the radius of the latter, determine the performance of the perovskites. The encouraging results obtained are exemplefied by Y 0.5 Sr 0.5 MnO 3 which releases 483 µmol/g of O 2 at 1673 K and produces 757 µmol/g of CO from CO 2 at 1173 K. The production of H 2 from H 2 O is also quite appreciable. Modification of the B site ion of the perovskite also affects the performance. In addition to perovskites, we present the generation of H 2 based on the Mn 3 O 4 /NaMnO 2 cycle briefly. - Graphical abstract: Ln 0.5 A 0.5 Mn 1−x M x O 3 (Ln=lanthanide; A=Ca, Sr; M=Al, Ga, Sc, Mg, Cr, Fe, Co) perovskites are employed for the two step thermochemical splitting of CO 2 and H 2 O for the generation of CO and H 2 . - Highlights: • Perovskite oxides based on Mn are ideal for the two-step thermochemical splitting of CO 2 and H 2 O. • In Ln 1−x A x MnO 3 perovskite (Ln=rare earth, A=alkaline earth) both Ln and A ions play major roles in the thermochemical process. • H 2 O splitting is also achieved by the use of the Mn 3 O 4 -sodium carbonate system. • Thermochemical splitting of CO 2 and H

Anti-bombing insensitivity life of molybdenum cathode doped with La{sub 2}O{sub 3} and Y{sub 2}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Wang Jinshu [School of Materials Science and Engineering, Beijing University of Technology, Beijing 100022 (China)]. E-mail: wangjsh@bjut.edu.cn; Wang Yiman [School of Materials Science and Engineering, Beijing University of Technology, Beijing 100022 (China); Zhou Meiling [School of Materials Science and Engineering, Beijing University of Technology, Beijing 100022 (China)

2006-03-15

Anti-bombing insensitivity of La{sub 2}O{sub 3}-Y{sub 2}O{sub 3}-Mo secondary emitter has been studied in this paper. The variation of maximum secondary emission coefficient {delta} {sub max} with time was measured. The cathode after life experiment was analyzed by means of HRM, SEM, EDS and XRD. The results showed that {delta} {sub max} of La{sub 2}O{sub 3}-Y{sub 2}O{sub 3}-Mo cathode operating at 1100 deg. C under continuous electron bombardment of 300 W/cm{sup 2} was still about 2.5 after 1000 h operation, indicating that this kind of cathode had good anti-bombing insensitivity. In the internal part of the cathode, RE{sub 2}O{sub 3} (rare earth oxide) and molybdenum grains distributed alternately and there existed a certain relationship between crystallographic orientation of RE{sub 2}O{sub 3} and that of molybdenum. It was found that a RE{sub 2}O{sub 3} layer was formed on the surface after operation. The high {delta} {sub max} of La{sub 2}O{sub 3}-Y{sub 2}O{sub 3}-Mo cathode was related to the RE{sub 2}O{sub 3} layer on the surface and the amount of nanosized La{sub 2}O{sub 3} particles on the Y{sub 2}O{sub 3} layer.

A systemic study of stepwise chlorination-chemical vapor transport characteristics of pure rare earth oxides from Sc2O3 to Lu2O3 mediated by alkaline chlorides as complex former

International Nuclear Information System (INIS)

Sun Yanhui; He Peng; Chen Huani

2007-01-01

A systematic study has been carried out for the stepwise chlorination-chemical vapor transport (SC-CVT) characteristics of pure rare earth oxides from Sc 2 O 3 to Lu 2 O 3 mediated by the vapor complexes KLnCl 4 and NaLnCl 4 (Ln = Sc, Y and La-Lu) used NaCl and KCl as complex former, respectively. The results showed that the SC-CVT characteristics are similarly for NaCl and KCl as complex former, the main deposition temperature of the rare earth chlorides LnCl 3 is in the increasing order ScCl 3 3 3 , and then with a systematically decreasing trend from the early lanthanide chlorides to the end one. The results also showed that the total transported amount of the produced chlorides is YCl 3 > ScCl 3 , and they are much higher than that of most lanthanoid chlorides. For lanthanoids, the total transported amount of chloride increases systematically from the early lanthanoid chlorides to the end one except for EuCl 3 and GdCl 3 mediated by KCl and NaCl as complex former, respectively, which showed the divergence effect of Gd in the total transport efficiency. But there are some differences in SC-CVT characteristics of pure rare earth oxide mediated by KCl and NaCl as complex former, that is the main deposition temperature region for the same rare earth element was lower for KCl than that for NaCl as complex former except for LaCl 3 , CeCl 3 , YbCl 3 and LuCl 3 , while the total transport amount of rare earth chloride for KCl as complex former is higher than that for NaCl except for LaCl 3 and EuCl 3 . More over, the discussion was carried out for Sc and Y on the one hand and the lanthanides contain 4f electron as another hand based on the 4f electron hybridization assumption. Further more, the transport characteristics of rare earth oxides with alkaline chlorides as complex former in this study were compared to that with AlCl 3 as complex former

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

International Nuclear Information System (INIS)

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

2015-01-01

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

Effect of RE (Nd3+, Sm3+) oxide on structural, optical properties of Na2O-Li2O-ZnO-B2O3 glass system

Science.gov (United States)

Hivrekar, Mahesh M.; Bhoyar, D. N.; Mande, V. K.; Dhole, V. V.; Solunke, M. B.; Jadhav, K. M.

2018-05-01

Zinc borate glass activated with rare earth oxide (Nd2O3, Sm2O3) of Na2O-Li2O-ZnO-B2O3 quaternary system has been prepared successfully by melt quenching method. The nucleation and growth of RE oxide were controlled temperature range 950-1000° C and rapid cooling at room temperature. The physical, structural and optical properties were characterized by using X-ray diffraction (XRD), SEM, Ultraviolet-visible spectroscopy (UV-Vis). XRD and SEM studies confirmed the amorphous nature, surface morphology of prepared zinc borate glass. The physical parameters like density, molar volume, molar mass of Nd3+, Sm3+ doped borate glass are summarized in the present article. The optical absorption spectra along with tauc's plot are presented. The optical energy band gap increases due to the addition of rare earth oxide confirming the role of network modifier.

Structural, magnetic and electronic properties of rare earth ternary oxides Li Ln(II) 2 Ln(III)O4

International Nuclear Information System (INIS)

Malki, M.

1987-06-01

Properties of a new class of rare earth ternary oxides Li Ln(II) 2 Ln(III)O 4 where Ln(II) is a divalent metal (Sr, Eu) and Ln(III) a trivalent rare earth (Eu, Gd, Dy, Er and Y). These orthorhombic compounds (type Li Eu 3 O 4 ) allow the study of many magnetic phenomena and their evolution in function of the nature of Ln(II) and Ln(III): diamagnetic ions Sr 2+ , Y 3+ ; isotrope magnetic ions: Eu 2+ , Gd 3+ and anisotrope magnetic ions Dy 3+ , Er 3+ . Magnetic and electric properties are obtained by classical techniques and from hyperfine interaction by Moessbauer spectroscopy. The possibility to use several Moessbauer resonance (nuclei Eu 151, Gd 155, Dy 161 and Er 166) completes informations obtained by the macroscopic study [fr

A Comparative Study of Er3+, Er3+-Eu3+, Er3+-Tb3+, and Er3+-Eu3+-Tb3+ Codoped Y2O3 Nanoparticles as Optical Heaters

Directory of Open Access Journals (Sweden)

G. A. Sobral

2015-01-01

Full Text Available Fluorescence intensity ratio (FIR technique, based on the thermal coupling of H11/22 and S3/24 energy levels of erbium ions, was used to study the optical heating behavior of rare earth doped yttrium oxide nanophosphors (Y2O3:Er3+, Y2O3:Er3+-Eu3+, Y2O3:Er3+-Tb3+, and Y2O3:Er3+-Eu3+-Tb3+ synthesized via PVA-assisted sol-gel route. The samples were optically heated by an 800 nm CW diode laser, while the upconverted green emissions were used to measure their temperatures in real time. The experimental results indicate that the studied nanoparticles are promising candidates to applications such as photothermal treatments and hyperthermia.

Phase Transformation Behavior of Oxide Particles Formed in Mechanically Alloyed Fe-5Y{sub 2}O{sub 3} Powder

Energy Technology Data Exchange (ETDEWEB)

Kim, Ga Eon; Choi, Jung-Sun; Noh, Sanghoon; Kang, Suk Hoon; Choi, Byoung Kwon; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Deajeon (Korea, Republic of); Kim, Young Do [Hanyang University, Seoul (Korea, Republic of)

2017-05-15

The phase transformation behavior of the oxides formed in mechanically alloyed Fe-5Y{sub 2}O{sub 3} powder is investigated. Non-stoichiometric Y-rich and Fe-rich oxides with sizes of less than 300 nm are observed in the mechanically alloyed powder. The diffusion and redistribution reactions of the elements in these oxides during heating of the powder above 800 ℃ were observed, and these reactions result in the formation of a Y{sub 3}Fe{sub 5}O{sub 12} phase after heating at 1050 ℃. Thus, it is considered that the Y{sub 2}O{sub 3} powder and some Fe powder are formed from the non-stoichiometric Y-rich and Fe-rich oxides after the mechanical alloying process, and a considerable energy accumulated during the mechanical alloying process leads to a phase transformation of the Y-rich and Fe-rich oxides to Y{sub α}Fe{sub β}O{sub γ}-type phase during heating.

Fabrication and characterization of Y2O3 dispersion strengthened copper alloys

International Nuclear Information System (INIS)

Carro, G.; Muñoz, A.; Monge, M.A.; Savoini, B.; Pareja, R.; Ballesteros, C.; Adeva, P.

2014-01-01

Three copper base materials were fabricated following different routes: cast Cu–1 wt.%Y (C-Cu1Y) produced by vacuum induction melting, and Cu–1 wt.%Y (PM-Cu1Y) and Cu–1 wt.%Y 2 O 3 (PM-Cu1Y 2 O 3 ) both processed by a powder metallurgy route and sintering by hot isostatic pressing. PM-Cu1Y alloy was prepared by cryomilling and PM-Cu1Y 2 O 3 by conventional milling at room temperature. The materials were characterized by X-ray diffraction, optical and electron microscopy and microhardness measurements. C-Cu1Y presents a characteristic eutectic microstructure while PM-Cu1Y 2 O 3 exhibits a composite like microstructure. Electron microscopy analyses of as-HIP PM-Cu1Y revealed irregular decoration of yttrium-rich oxides at the grain boundaries and an inhomogeneous dispersion of polygonal shaped yttrium-rich oxides dispersed in the Cu matrix. Tensile tests performed on PM-Cu–1Y on the temperature range of 293–773 K have showed a decrease of the yield strength at temperatures higher than 473 K, and monotonically decrease of the ultimate tensile strength and maximum plastic strain on increasing temperature

Creation of Y{sub 2}Ti{sub 2}O{sub 7} nanoprecipitates to strengthen the Fe-14Cr-3Al-2W steels by adding Ti hydride and Y{sub 2}O{sub 3} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wang, Linbo; Bai, Zhonglian; Shen, Hailong; Wang, Chenxi; Liu, Tong, E-mail: tongliu@buaa.edu.cn

2017-05-15

In order to prohibit the formation of large Y-Al-O precipitates, Ti hydride nanoparticles (NPs) were prepared and used to replace Ti as raw particles to fabricate the oxide dispersion strengthened (ODS) Fe-14Cr-3Al-2W-0.35Y{sub 2}O{sub 3} steels by mechanical alloying (MA) and hot isostatic pressing (HIP). As the content of Ti hydride increases from 0.1 to 0.5 and 1.0 wt%, the oxide nanoprecipitates in the ODS steels changes from Y{sub 3}Al{sub 5}O{sub 12} phase to Y{sub 2}Ti{sub 2}O{sub 7} phase (semicoherent with the matrix), and the particle size is successfully reduced. The tensile strength of the ODS steel increases remarkably with increasing Ti hydride content. The sample with 1.0 wt% Ti hydride exhibits a high strength of 1049 MPa at 25 °C and 278 MPa at 700 °C. The creation of Y{sub 2}Ti{sub 2}O{sub 7} nanoprecipitates by adding Ti hydride NPs opens a new way to control the structure and size of the oxide precipitates in the ODS steels. - Graphical abstract: The creation of Y{sub 2}Ti{sub 2}O{sub 7} nanoprecipitates by adding Ti hydride nanoparticles remarkably increases the mechanical properties of the Al-containing ODS steels. - Highlights: •TiH{sub 1.971} reacts with Y{sub 2}O{sub 3} to form Y{sub 2}Ti{sub 2}O{sub 7} in the Al-containing ODS steel. •Addition of TiH{sub 1.971} nanoparticles can prevent the formation of Y-Al-O phases. •Y{sub 2}Ti{sub 2}O{sub 7} nanoparticles share semicoherent interface with the ferrite matrix. •The mean size of oxide dispersion is reduced to 11.2 ± 7.1 nm with 1.0 wt% TiH{sub 1.971}. •The tensile strength of the ODS steel enlarges with increasing TiH{sub 1.971} content.

On the coexistence of copper-molybdenum bronzes: CuxMoO3 (0.2 yMoO3-z (0.1 2-O quasi-ternary system

International Nuclear Information System (INIS)

Warner, T.E.; Skou, E.M.

2010-01-01

Two copper-molybdenum bronzes: Cu y MoO 3-z (0.1 x MoO 3 (0.2 3 at 600 o C under argon in Pt crucibles. Powder XRD showed that the material with global composition '0.1Cu.MoO 3 ' comprises ∼Cu 0.15 MoO 3 and MoO 3 ; whilst '0.2Cu.MoO 3 ' comprises ∼Cu 0.15 MoO 3 and ∼Cu 0.23 MoO 3 . DTA performed on '0.2Cu.MoO 3 ' reveals a reversible solid state phase transition ∼520 o C under argon. Reacting equimolar amounts of Cu 2 O and MoO 2 at 600 o C in a Cu crucible under argon yields: Cu 6 Mo 5 O 18 , Cu and MoO 2 . A tentative subsolidus Cu-MoO 2 -O isothermal (∼25 o C) phase diagram under argon is drawn from these data. Oxidation states of Cu and Mo within this system are discussed.

HRTEM Study of Oxide Nanoparticles in 16Cr-4Al-2W-0.3Ti-0.3Y2O3 ODS Steel

Energy Technology Data Exchange (ETDEWEB)

Hsiung, L; Fluss, M; Wall, M; Kimura, A

2009-11-18

Crystal and interfacial structures of oxide nanoparticles in 16Cr-4Al-2W-0.3Ti-0.3Y{sub 2}O{sub 3} ODS ferritic steel have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. Oxide nanoparticles with a complex-oxide core and an amorphous shell were frequently observed. The crystal structure of complex-oxide core is identified to be mainly monoclinic Y{sub 4}Al{sub 2}O{sub 9} (YAM) oxide compound. Orientation relationships between the oxide and matrix are found to be dependent on the particle size. Large particles (> 20 nm) tend to be incoherent and have a spherical shape, whereas small particles (< 10 nm) tend to be coherent or semi-coherent and have a faceted interface. The observations of partially amorphous nanoparticles lead us to propose three-stage mechanisms to rationalize the formation of oxide nanoparticles containing core/shell structures in as-fabricated ODS steels.

Electronic structure of the CuO3 chains in RBa2Cu3O6+x (R=Y or a rare earth)

International Nuclear Information System (INIS)

Aligia, A.A.; Gagliano, E.R.; Vairus, P.

1995-01-01

We consider the appropriate generalization of the three-band Hubbard model to describe the CuO 3 chains of RBa 2 Cu 3 O 6+x (R=Y or a rare earth). The model is mapped numerically into a t-J model with t∼0.85 eV and J∼0.2 eV. Making the reasonable assumption that ∼5% of the O atoms between two Cu atoms are lacking, the model allows an explanation of the optical conductivity σ(ω) of the chains, the small change of the occupation of the chains when Y is substituted by Pr, and the charge corrugations observed by scanning-tunneling microscopy

Nanocrystalline Ce 1- xY xO 2- x/2 (0≤ x≤0.35) Oxides via Carbonate Precipitation: Synthesis and Characterization

Science.gov (United States)

Li, Ji-Guang; Ikegami, Takayasu; Wang, Yarong; Mori, Toshiyuki

2002-10-01

A novel carbonate (co)precipitation method, employing nitrates as the starting salts and ammonium carbonate as the precipitant, has been used to synthesize nanocrystalline CeO 2 and Ce 1- xY xO 2- x/2 ( x≤0.35) solid-solutions. The resultant powders are characterized by elemental analysis, differential thermal analysis/thermogravimetry (DTA/TG), X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) analysis, and high-resolution scanning electron microscopy (HRSEM). Due to the direct formation of carbonate solid-solutions during precipitation, Ce 1- xY xO 2- x/2 solid-solution oxides are formed directly during calcination at a very low temperature of ˜300°C for 2 h. The thus-produced oxide nanopowders are essentially non-agglomerated, as revealed by BET in conjunction with XRD analysis. The solubility of YO 1.5 in CeO 2 is determined via XRD to be somewhere in the range from 27 to 35 mol%, from which a Y 2O 3-related type-C phase appears in the final product. Y 3+-doping promotes the formation of spherical nanoparticles, retards thermal decomposition of the precursors, and suppresses significantly crystallite coarsening of the oxides during calcination. The activation energy for crystallite coarsening increases gradually from 68.7 kJ mol -1 for pure CeO 2 to 138.6 kJ mol -1 for CeO 2 doped with 35 mol% YO 1.5. The dopant effects on crystallite coarsening is elaborated from the view point of solid-state chemistry.

Phase formation in the (1-y)BiFeO{sub 3}-yBiScO{sub 3} system under ambient and high pressure

Energy Technology Data Exchange (ETDEWEB)

Salak, A.N., E-mail: salak@ua.pt [Department of Materials and Ceramic Engineering and CICECO – Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro (Portugal); Khalyavin, D.D., E-mail: dmitry.khalyavin@stfc.ac.uk [ISIS Facility, Rutherford Appleton Laboratory, Chilton, OX11 0QX Didcot (United Kingdom); Pushkarev, A.V.; Radyush, Yu.V.; Olekhnovich, N.M. [Scientific-Practical Materials Research Centre of NAS of Belarus, P. Brovka Street, 19, 220072 Minsk (Belarus); Shilin, A.D.; Rubanik, V.V. [Institute of Technical Acoustics of NAS of Belarus, Lyudnikov Avenue, 13, 210023 Vitebsk (Belarus)

2017-03-15

Formation and thermal stability of perovskite phases in the BiFe{sub 1-y}Sc{sub y}O{sub 3} system (0≤y≤0.70) were studied. When the iron-to-scandium substitution rate does not exceed about 15 at%, the single-phase perovskite ceramics with the rhombohedral R3c symmetry (as that of the parent compound, BiFeO{sub 3}) can be prepared from the stoichiometric mixture of the respective oxides at ambient pressure. Thermal treatment of the oxide mixtures with a higher content of scandium results in formation of two main phases, namely a BiFeO{sub 3}-like R3c phase and a cubic (I23) sillenite-type phase based on γ-Bi{sub 2}O{sub 3}. Single-phase perovskite ceramics of the BiFe{sub 1-y}Sc{sub y}O{sub 3} composition were synthesized under high pressure from the thermally treated oxide mixtures. When y is between 0 and 0.25 the high-pressure prepared phase is the rhombohedral R3c with the √2a{sub p}×√2a{sub p}×2√3a{sub p} superstructure (a{sub p} ~ 4 Å is the pseudocubic perovskite unit-cell parameter). The orthorhombic Pnma phase (√2a{sub p}×4a{sub p}×2√2a{sub p}) was obtained in the range of 0.30≤y≤0.60, while the monoclinic C2/c phase (√6a{sub p}×√2a{sub p}×√6a{sub p}) is formed when y=0.70. The normalized unit-cell volume drops at the crossover from the rhombohedral to the orthorhombic composition range. The perovskite BiFe{sub 1-y}Sc{sub y}O{sub 3} phases prepared under high pressure are metastable regardless of their symmetry. At ambient pressure, the phases with the compositions in the ranges of 0.20≤y≤0.25, 0.30≤y<0.50 and 0.50≤y≤0.70 start to decompose above 970, 920 and 870 K, respectively. - Graphical abstract: Formation of perovskite phases in the BiFe{sub 1-y}Sc{sub y}O{sub 3} system when y≥0.15 requires application of pressure of several GPa. The phases formed under high pressure: R3c (0.20≤y≤0.25), Pnma (0.30≤y≤0.60) and C2/c (y≥0.70) are metastable. - Highlights: • Maximal Fe-to-Sc substitution rate in BiFeO

Oxygen permeation flux through La1-ySryFeO3 limited by the carbon monoxide oxidation rate

NARCIS (Netherlands)

van Hassel, B.A.; van Hassel, B.A.; ten Elshof, Johan E.; Bouwmeester, Henricus J.M.

1995-01-01

The oxygen permeation flux through La1-ySryFeO3-δ (y = 0.1, 0.2) in a large oxygen partial pressure gradient (air/CO, CO2 mixture) was found to be limited by the carbon monoxide oxidation rate at the low oxygen partial pressure side of the membrane. The oxygen permeation flux through the membrane

Visible light water oxidation using a co-catalyst loaded anatase-structured Ti(1-(5x/4))Nb(x)O(2-y-δ)N(y) compound.

Science.gov (United States)

Breault, Tanya M; Brancho, James J; Guo, Ping; Bartlett, Bart M

2013-08-19

The photocatalytic activity of anatase-structured Ti(1-(5x/4))Nb(x)O(2-y-δ)N(y) (x = 0.25, y = 0.02; NbN-25) was examined for water oxidation under UV and visible light irradiation. The semiconductor was prepared by sol-gel processing followed by nitridation in flowing ammonia and exhibits an indirect optical gap of 2.2 eV. Ti(1-(5x/4))Nb(x)O(2-y-δ)N(y) was loaded with RuO2 by an impregnation technique, and optimized conditions reveal that 1 wt % RuO2 generates 16 μmol O2 from water with concomitant IO3(-) reduction after 3 h of illumination under simulated solar radiation at a flux of 600 mW/cm(2) illumination, which corresponds to 6-sun AM1.5G illumination (compared to no detectible O2 without the RuO2 cocatalyst). A series of cut-on filters shows that the catalyst-loaded semiconductor evolves O2 for λ ≤ 515 nm, and a gas-phase mass spectrometry isotope labeling experiment shows that irradiating an iodate solution in H2(18)O in the presence of 1 wt % RuO2 loaded on NbN-25 gives rise to catalytic water oxidation: both (36)O2 and (34)O2 are observed. It is unclear whether (16)O arises from IO3(-) or surface reconstruction on the photocatalyst, but ICP-AES analysis of the postirradiated solution shows no dissolved metal ions.

Ba{sub y}Sr{sub 1−y}TiO{sub 3} buffer layers for strain tuning of infinite-layer Sr{sub 1−x}La{sub x}CuO{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Sakuma, Keita, E-mail: sakuma.keita@d.mbox.nagoya-u.ac.jp; Ito, Masataka; He, Yilun; Hajiri, Tetsuya; Ueda, Kenji; Asano, Hidefumi

2016-08-01

We report on the precise tuning of lattice strain in an infinite-layer electron-doped high temperature superconductor Sr{sub 1−x}La{sub x}CuO{sub 2} (SLCO; a{sub SLCO} = 0.3949 nm for x = 0.1), which is a perovskite-related oxide, using perovskite BaTiO{sub 3}–SrTiO{sub 3} (BSTO; Ba{sub y}Sr{sub 1−y}TiO{sub 3}) buffer layers. The BSTO buffer layers formed on (001) (La{sub 0.18}Sr{sub 0.82})(Al{sub 0.59}Ta{sub 0.41})O{sub 3} substrates by magnetron sputtering were fully relaxed with high crystalline quality due to high oxygen partial pressure deposition and post annealing at 950 °C. The lattice constants of the BSTO buffer layers could be controlled in the range of 0.3926–0.3973 nm by changing the Ba content (y = 0.2–0.7). These BSTO buffer layers allow coherent growth of SLCO thin films, and a clear dependence of the superconducting transition temperature on the lattice strain was observed. The fabrication of these BSTO/superconductor heterostructures may provide novel devices composed of functional perovskite thin films, in addition to a general approach for the precise control of lattice strain in functional perovskite thin films. - Highlights: • Ba{sub y}Sr{sub 1−y}TiO{sub 3} buffer layers were developed for the strain tuning of perovskite-related oxides. • Strain effect in Sr{sub 1−x}La{sub x}CuO{sub 2} was investigated by using Ba{sub y}Sr{sub 1−y}TiO{sub 3} buffer layers. • Ba{sub y}Sr{sub 1−y}TiO{sub 3} buffer layers can be used to tune the strain in other perovskite oxides.

Control of Co content and SOFC cathode performance in Y1-ySr2+yCu3-xCoxO7+δ

Science.gov (United States)

Šimo, F.; Payne, J. L.; Demont, A.; Sayers, R.; Li, Ming; Collins, C. M.; Pitcher, M. J.; Claridge, J. B.; Rosseinsky, M. J.

2014-11-01

The electrochemical performance of the layered perovskite YSr2Cu3-xCoxO7+δ, a potential solid oxide fuel cell (SOFC) cathode, is improved by increasing the Co content from x = 1.00 to a maximum of x = 1.30. Single phase samples with x > 1.00 are obtained by tuning the Y/Sr ratio, yielding the composition Y1-ySr2+yCu3-xCoxO7+δ (where y ≤ 0.05). The high temperature structure of Y0.95Sr2.05Cu1.7Co1.3O7+δ at 740 °C is characterised by powder neutron diffraction and the potential of this Co-enriched material as a SOFC cathode is investigated by combining AC impedance spectroscopy, four-probe DC conductivity and powder XRD measurements to determine its electrochemical properties along with its thermal stability and compatibility with a range of commercially available electrolytes. The material is shown to be compatible with doped ceria electrolytes at 900 °C.

Cathodoluminescence of rare earth implanted Ga2O3 and GeO2 nanostructures.

Science.gov (United States)

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

2011-07-15

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

Cathodoluminescence of rare earth implanted Ga2O3 and GeO2 nanostructures

International Nuclear Information System (INIS)

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

2011-01-01

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

A divalent rare earth oxide semiconductor: Yttrium monoxide

Energy Technology Data Exchange (ETDEWEB)

Kaminaga, Kenichi; Sei, Ryosuke [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); Department of Chemistry, Tohoku University, Sendai 980-8578 (Japan); Hayashi, Kouichi [Department of Environmental and Materials Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Happo, Naohisa [School of Information Sciences, Hiroshima City University, Hiroshima 731-3194 (Japan); Tajiri, Hiroo [Japan Synchrotron Radiation Research Institute (JASRI)/SPring-8, Sayo 679-5198 (Japan); Oka, Daichi; Fukumura, Tomoteru, E-mail: tomoteru.fukumura.e4@tohoku.ac.jp [Department of Chemistry, Tohoku University, Sendai 980-8578 (Japan); Hasegawa, Tetsuya [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan)

2016-03-21

Rare earth oxides are usually widegap insulators like Y{sub 2}O{sub 3} with closed shell trivalent rare earth ions. In this study, solid phase rock salt structure yttrium monoxide, YO, with unusual valence of Y{sup 2+} (4d{sup 1}) was synthesized in a form of epitaxial thin film by pulsed laser deposition method. YO has been recognized as gaseous phase in previous studies. In contrast with Y{sub 2}O{sub 3}, YO was dark-brown colored and narrow gap semiconductor. The tunable electrical conductivity ranging from 10{sup −1} to 10{sup 3} Ω{sup −1 }cm{sup −1} was attributed to the presence of oxygen vacancies serving as electron donor. Weak antilocalization behavior observed in magnetoresistance indicated significant role of spin-orbit coupling as a manifestation of 4d electron carrier.

Rare-Earth Oxide Ion (Tm3+, Ho3+, and U3+) Doped Glasses and Fibres for 1.8 to 4 Micrometer Coherent and Broadband Sources

Science.gov (United States)

2006-07-24

oxide ( TeO2 ) , fluorine- containing silicate (SiOF2) and germanate (GeOF2) glass hosts for each dopant by characterising the spectroscopic properties...Earth Oxide Ion (Tm3+, Ho3+, And U3+) Doped Glasses And Fibres For 1.8 To 4 Micrometer Coherent And Broadband Sources 5c. PROGRAM ELEMENT NUMBER 5d...Rare-earth oxide ion (Tm3+, Ho3+, and U3+) doped glasses and fibres for 1.8 to 4 micrometer coherent and broadband sources Report prepared

Synthesis of Y2O3: Eu added the group 1 or 2 elements using complex-polymerization and its luminescent properties

International Nuclear Information System (INIS)

Park, Sang Mi; Jang, Ho G.; Kim, Chang Hae; Park, Joung Kyu; Park, Hee Dong

2001-01-01

Europium activated yttrium oxide (Y 2 O 3 :Eu) is extensively applied to red phosphor for Flat Panel Display because of its high efficiency and the thermal and chemical stability. Flat Panel Display screen which have a high resolution and high efficiency needs to the phosphors of ideally small size spherical particle. In this study, we prepared a Y 2 O 3 :Eu phosphor using polymeric precursor methods and investigated the codoping effect by introducing the group 1 or 2 elements to Y 2 O 3 :Eu phosphor in view of improvement of luminance efficiency

Influence of annealing temperature on structural and optical properties of SiO{sub 2}:RE{sub 2}O{sub 3} [RE = Y, Gd] powder

Energy Technology Data Exchange (ETDEWEB)

Ahlawat, Rachna, E-mail: rachnaahlawat2003@yahoo.com

2015-07-25

Highlights: • Sol–gel process is used to obtain spherical nanocrystallites of SiO{sub 2}:RE{sub 2}O{sub 3} [RE = Y, Gd] powder. • Effect of four steps annealing is studied on micro strain, nanocrystallite size and dislocation density. • Optical properties are examined by absorption spectra and PL. • SiO{sub 2}:RE{sub 2}O{sub 3} [RE = Y, Gd] binary oxides are promising materials for high temperature structural applications. - Abstract: SiO{sub 2}:RE{sub 2}O{sub 3} [RE = Y, Gd] powder were prepared by wet chemical technique and the prepared binary oxides annealed at 500 °C and 900 °C. The crystalline structure, phase transformation, and surface morphologies of as-prepared and annealed samples were investigated by XRD and TEM. The normal transmission was measured using FTIR spectroscopy. Optical properties have been studied with UV–Vis spectroscopy and PL study. XRD results shows that the as prepared samples of SiO{sub 2}:RE{sub 2}O{sub 3} [RE = Y, Gd] powder has mixed phases of RE(NO{sub 3}){sub 3} and Si(OH){sub 3}. However, cubic rare earth oxide phase alone is found for annealed samples. The strain values are calculated from W–H plot for annealed samples. TEM micrograph shows that the samples are composed of individual spherical nanocrystallites at 500 °C and aggregated nanocrystallites at 900 °C. From the UV–Vis spectra, it is found that the position of the absorption peak is shifted toward the higher wavelength side when annealing temperature is increased. In the PL spectra, the broad emission bands are observed between 570–600 nm and the presence of O–Si–O (silica) and metal oxide is confirmed by FTIR spectra.

Fabrication and characterization of Y{sub 2}O{sub 3} dispersion strengthened copper alloys

Energy Technology Data Exchange (ETDEWEB)

Carro, G.; Muñoz, A. [Departamento de Física, Universidad Carlos III de Madrid, 28911 Leganés (Spain); Monge, M.A., E-mail: mmonge@fis.uc3m.es [Departamento de Física, Universidad Carlos III de Madrid, 28911 Leganés (Spain); Savoini, B.; Pareja, R.; Ballesteros, C. [Departamento de Física, Universidad Carlos III de Madrid, 28911 Leganés (Spain); Adeva, P. [Centro Nacional de Investigaciones Metalúrgicas, CSIC, Av. Gregorio del Amo, 8, 28040 Madrid (Spain)

2014-12-15

Three copper base materials were fabricated following different routes: cast Cu–1 wt.%Y (C-Cu1Y) produced by vacuum induction melting, and Cu–1 wt.%Y (PM-Cu1Y) and Cu–1 wt.%Y{sub 2}O{sub 3} (PM-Cu1Y{sub 2}O{sub 3}) both processed by a powder metallurgy route and sintering by hot isostatic pressing. PM-Cu1Y alloy was prepared by cryomilling and PM-Cu1Y{sub 2}O{sub 3} by conventional milling at room temperature. The materials were characterized by X-ray diffraction, optical and electron microscopy and microhardness measurements. C-Cu1Y presents a characteristic eutectic microstructure while PM-Cu1Y{sub 2}O{sub 3} exhibits a composite like microstructure. Electron microscopy analyses of as-HIP PM-Cu1Y revealed irregular decoration of yttrium-rich oxides at the grain boundaries and an inhomogeneous dispersion of polygonal shaped yttrium-rich oxides dispersed in the Cu matrix. Tensile tests performed on PM-Cu–1Y on the temperature range of 293–773 K have showed a decrease of the yield strength at temperatures higher than 473 K, and monotonically decrease of the ultimate tensile strength and maximum plastic strain on increasing temperature.

Generation of H{sub 2} and CO by solar thermochemical splitting of H{sub 2}O and CO{sub 2} by employing metal oxides

Energy Technology Data Exchange (ETDEWEB)

Rao, C.N.R., E-mail: cnrrao@jncasr.ac.in; Dey, Sunita

2016-10-15

Generation of H{sub 2} and CO by splitting H{sub 2}O and CO{sub 2} respectively constitutes an important aspect of the present-day concerns with energy and environment. The solar thermochemical route making use of metal oxides is a viable means of accomplishing these reduction reactions. The method essentially involves reducing a metal oxide by heating and passing H{sub 2}O or CO{sub 2} over the nonstoichiometric oxide to cause reverse oxidation by abstracting oxygen from H{sub 2}O or CO{sub 2}. While ceria, perovskites and other oxides have been investigated for this purpose, recent studies have demonstrated the superior performance of perovskites of the type Ln{sub 1−x}A{sub x}Mn{sub 1−y}M{sub y}O{sub 3} (Ln=rare earth, A=alkaline earth, M=various +2 and +3 metal ions), in the thermochemical generation of H{sub 2} and CO. We present the important results obtained hitherto to point out how the alkaine earth and the Ln ions, specially the radius of the latter, determine the performance of the perovskites. The encouraging results obtained are exemplefied by Y{sub 0.5}Sr{sub 0.5}MnO{sub 3} which releases 483 µmol/g of O{sub 2} at 1673 K and produces 757 µmol/g of CO from CO{sub 2} at 1173 K. The production of H{sub 2} from H{sub 2}O is also quite appreciable. Modification of the B site ion of the perovskite also affects the performance. In addition to perovskites, we present the generation of H{sub 2} based on the Mn{sub 3}O{sub 4}/NaMnO{sub 2} cycle briefly. - Graphical abstract: Ln{sub 0.5}A{sub 0.5}Mn{sub 1−x}M{sub x}O{sub 3} (Ln=lanthanide; A=Ca, Sr; M=Al, Ga, Sc, Mg, Cr, Fe, Co) perovskites are employed for the two step thermochemical splitting of CO{sub 2} and H{sub 2}O for the generation of CO and H{sub 2}. - Highlights: • Perovskite oxides based on Mn are ideal for the two-step thermochemical splitting of CO{sub 2} and H{sub 2}O. • In Ln{sub 1−x}A{sub x}MnO{sub 3} perovskite (Ln=rare earth, A=alkaline earth) both Ln and A ions play major roles

Development of AL{sub 2}O{sub 3} - ZrO{sub 2} ceramic composite reinforced with rare earth oxides (Y{sub 2}O)3) for inert coating of storage and transport systems of crude petroleum; Desenvolvimento de composito ceramico Al{sub 2}O{sub 3} - ZrO{sub 2} reforcada com oxido de terra rara para sistema de armazenamento e transporte de petroleo cru

Energy Technology Data Exchange (ETDEWEB)

Silva, J.C.; Yadava, Y.P.; Sanguinetti Ferreira, R.A.; Albuquerque, L.T., E-mail: juliana.carvalhosilva@ufpe.br [Universidade Federal de Pernambuco (UFPE), Jaboatao de Guararapes, PE (Brazil). Centro de Tecnologia. Departamento de Engenharia Mecanica

2014-07-01

The advancement of the oil sector has generated the need for the use of materials resistant to aggressive environments to oil. Although ceramics have high melting point and high hardness is, on the other hand, more fragile and less tough, which can cause damage to the metal structure. The Al{sub 2}O{sub 3} based ceramics reinforced with rare earth oxide can improve tenaciousness and makes the ceramic material more resistant. This article aims to present the production of composite Al{sub 2}O{sub 3} - Y{sub 2}O{sub 3} stabilized ZrO{sub 2} by uniaxial pressing, following sintering (1200-1350 deg C). Structural and microstructural characterizations as XRD (X-Ray Diffraction) and SEM (Scanning Electron Microscopy) and mechanical tests as Vickers hardness, % absorption and % linear shrinkage were conducted to evaluate the feasibility of using the composite and ceramic coating for storage and transportation of oil tanks. The results indicate that the proportions of 5%, 10% and 30% ZrO{sub 2} make it suitable as a good composite suitable coating. (author)

Relationship between electrical and structural properties in Pr2/3+xTiO3±y

International Nuclear Information System (INIS)

Kirsanov, N.A.; Bazuev, G.V.

1987-01-01

Synthesis conditions results of X-ray diffraction investigations and electric properties of oxide titanium bronzes (OTB) of praseodymium Pr 2/3+x TiO 3±y in homogeneity region are presented. Change of crystal lattice symmetry in the region of existence of oxide titanium bronzes Pr 2/3+x TiO 3 ± y (O ≤ x ≤ 1/3) was revealed. Specific electrical resistance measurements enabled to conclude that d-electrons of Ti 3+ cations were characterized by collectivized behaviour, conditioned by formation of harrow, partially occupied π*-zone

Characterization and carbon monoxide oxidation activity of La1-ySryCr1-xRuxO3 perovskites

Directory of Open Access Journals (Sweden)

C. MARINOVA

2000-01-01

Full Text Available The oxidation of CO over La1-ySryCr1-xRuxO3 perovskite type oxides with y=0.3 and 0 £ x £ 0.100 have been studied. X-ray fluorescence analysis confirmed that content of elements in the bulk corresponds to the established nominal perovskite stoichiometry, indicating that no significant oxidation of ruthenium into volatile polyvalent oxides with their consequented escape from the sample occurred in air up to the temperature of 1000°C. According to X-ray diffraction analysis, all sampls achieved the perovskite hexagonal with the presence of some SrCrO4. X-ray photoelectron spectroscopy analysis of ruthenium samples shows higher Ru and Sr surface concentraitions than in the bulk. The binding energy for Ru3p is virtually the same in all samples and consistent with that of Ru4+ (463.6-464.3eV. Kinetic studies were performed in a differential recycle reactor with a recycling ratio 80. The results show that substitution of Ru4+ for Cr3+ in La1-ySryCrO3 leads to a significant increase in both the activity and the activation energy. The global CO oxidation rate, referred on the BET surface area, correlates with the surface Ru4+ atomic concentraiton. Hence, the activity reflect the surface enrichment in ruthenium. Moreover, an identical apparent activation energy E = 93 kJ/mol and the same specific rate per ruthenium surface ion were obtained for samples with a Ru content x ³ 0.05 suggest that exposed Ru4+ ions mainly participate in the reaction.

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

International Nuclear Information System (INIS)

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

2008-01-01

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

X-ray fluorescence analysis of terbium oxide for rare earth impurities

International Nuclear Information System (INIS)

Chandola, L.C.; Machado, I.J.; Mohile, A.N.

1975-01-01

A method for the determination of Sm 2 O 3 , Eu 2 O 3 , Gd 2 O 3 , Dy 2 O 3 , Ho 2 O 3 and Y 2 O 3 in terbium oxide is described. The sample is converted to terbium oxalate, mixed with boric acid binder in the ratio 2:1, pelleted at a pressure of 20 tons over a boric acid backing pellet and irradiated with x-rays from a tungsten tube operated by Philips PW 1140 generator. The secondary x-rays thus generated are analysed by a LiF (200) crystal in Philips PW 1220 x-ray fluorescence spectrometer using suitable detectors. The minimum determination limit (MDL) is 0.01% for all rare earth oxides determined except for Y 2 O 3 for which it is 0.005%. (author)

A divalent rare earth oxide semiconductor: Yttrium monoxide

Science.gov (United States)

Kaminaga, Kenichi; Sei, Ryosuke; Hayashi, Kouichi; Happo, Naohisa; Tajiri, Hiroo; Oka, Daichi; Fukumura, Tomoteru; Hasegawa, Tetsuya

Rare earth sesquioxides like Y2O3 are known as widegap insulators with the highly stable closed shell trivalent rare earth ions. On the other hand, rare earth monoxides such as YO have been recognized as gaseous phase, and only EuO and YbO were thermodynamically stable solid-phase rock salt monoxides. In this study, solid-phase rock salt yttrium monoxide, YO, was synthesized in a form of epitaxial thin film by pulsed laser deposition method. YO possesses unusual valence of Y2+ ([Kr] 4d1) . In contrast with Y2O3, YO was narrow gap semiconductor with dark-brown color. The electrical conductivity was tunable from 10-1 to 103 Ω-1 cm-1 by introducing oxygen vacancies as electron donor. Weak antilocalization behavior was observed indicating significant spin-orbit coupling owing to 4 d electron carrier. The absorption spectral shape implies the Mott-Hubbard insulator character of YO. Rare earth monoixdes will be new platform of functional oxides. This work was supported by JST-CREST, the Japan Society for the Promotion of Science (JSPS) with Grant-in-Aid for Scientific Research on Innovative Areas (Nos. 26105002 and 26105006), and Nanotechnology Platform (Project No.12024046) of MEXT, Japan.

Nano rare-earth oxides induced size-dependent vacuolization: an independent pathway from autophagy.

Science.gov (United States)

Zhang, Ying; Yu, Chenguang; Huang, Guanyi; Wang, Changli; Wen, Longping

2010-09-07

Four rare earth oxides have been shown to induce autophagy. Interestingly, we often noticed plentiful vacuolization, which was not always involved in this autophagic process. In this study, we investigated three other rare-earth elements, including Yttrium (Y), Ytterbium (Yb), and Lanthanum (La). Autophagic effect could be induced by all of them but only Y(2)O(3) and Yb(2)O(3) could cause massive vacuolization. Y(2)O(3) and Yb(2)O(3) treated by sonication or centrifugation to reduce particle size were used to test vacuolization level in HeLa cell lines. The results showed that rare earth oxides-induced vacuolization is size-dependent and differs from autophagic pathway. To further clarify the characteristics of this autophagic process, we used MEF Atg-5 (autophagy associated gene 5) knockout cell line, and the result showed that the autophagic process induced by rare earth oxides is Atg-5-dependent and the observed vacuolization was independent from autophagy. Similar results could also be observed in our tests on 3-methyladenine(3-MA), a well-known autophagy inhibitor. In conclusion, for the first time, we clarified the relationship between massive vacuolization and autophagic process induced by rare earth oxides and pointed out the size effect of rare earth oxides on the formation of vacuoles, which give clues to further investigation on the mechanisms underlying their biological effects.

Neutron irradiation damage in Al2O3 and Y2O3

International Nuclear Information System (INIS)

Clinard, F.W. Jr.; Bunch, J.M.; Ranken, W.A.

1975-01-01

Two ceramics under consideration for use in fusion reactors, Al 2 O 3 and Y 2 O 3 , were irradiated in the EBR-II fission reactor at 650, 875, and 1025 0 K to fluences between 2 and 6 x 10 21 n/cm 2 (E greater than 0.1 MeV). Samples evaluated include sapphire, Lucalox, alumina, Y 2 O 3 , and Y 2 O 3 -10 percent ZrO 2 (Yttralox). All Al 2 O 3 specimens swelled significantly (1 to 3 percent), with most of the growth observed in sapphire along the c-axis at the higher temperatures. Al 2 O 3 samples irradiated at 875 to 1025 0 K contained a high density of small aligned ''pores''. Irradiated Y 2 O 3 -based ceramics exhibited dimensional stability and a defect content consisting primarily of unresolved damage and/or dislocation loops. The behavior of these ceramics under irradiation is discussed, and the relevance of fission neutron damage studies to fusion reactor applications is considered. (auth)

Synthesis and cathodoluminescent properties of Y2SiO5:Tb3+ phosphors prepared from uniform precursor

International Nuclear Information System (INIS)

Fan Deyong; Yang Sen; Wang Jieqiong; Zheng Aqun; Song Xiaoping; Yu Demei

2012-01-01

The luminescent properties of phosphors are sensitive to the size of phosphor particles. The commercial Y 2 SiO 5 :Tb 3+ phosphors usually show relatively larger particle size (5–10 μm) due to the irregular morphology of rare earth oxide precursor and thus degrade the luminescent properties. In this paper, we report the Y 2 SiO 5 :Tb 3+ phosphors synthesized from the uniform Tb-doped Y 2 O 3 precursor by a homogeneous precipitation method. Compared with the commercial phosphors, the obtained Y 2 SiO 5 :Tb 3+ phosphors manifest the uniform morphology with much smaller particles distributing from 0.8 μm to 1.9 μm. Consequently, the cathodoluminescent intensity under low excitation voltage (1–5 kV) was increased, demonstrating a strong green emission with a dominant wavelength of 545 nm. Our results indicate an effective way to develop the high-quality phosphors for field emission display. - Highlights: ► The Y 2 SiO 5 :Tb 3+ phosphors are synthesized by a homogeneous precipitation method. ► They manifest the uniform morphology with much smaller particles than commercial one. ► The corresponding cathodoluminescent intensity of green emission is greatly enhanced. ► Our results indicate an effective way to develop the high-quality phosphors for FED.

Effect of H2O and Y(O on Oxidation Behavior of NiCoCrAl Coating Within Thermal Barrier Coating

Directory of Open Access Journals (Sweden)

WANG Yi-qun

2017-04-01

Full Text Available NiCoCrAl coatings containing Y and Y oxide were made using vacuum plasma deposition and high-velocity oxygen fuel respectively, high temperature oxidation dynamics and cross-section microstructures of NiCoCrAl+Y and NiCoCrAl+Y(O coatings in Ar-16.7%O2, Ar-3.3%H2O and Ar-0.2%H2-0.9%H2O at 1100℃ were investigated by differential thermal analysis (DTA and optical and electron microscope. The influencing mechanism of Y oxide on the oxidation of coatings at different atmosphere was compared by computation using First-Principles. The results show that Al2O3 layer on NiCoCrAl+Y coatings has more holes for internal oxidation on account of the element Y diffusion and enrichment on the interface. In addition, steam can promote the internal oxidation. While a thinner and uniform alumina form on NiCoCrAl+Y(O coatings because element Y is pinned by oxygen atoms during the preparation of coatings. Water vapor has less influence on protective alumina formation on the NiCoCrAl+Y(O coating. Therefore, oxidation behavior of NiCoCrAl coatings vary in composition and structure in different oxidizing atmosphere. Besides, Y and Y-enrichment oxides have key influences on the microstructure and the growth rate.

Diffusion barriers of Al2O3 to reduce the bondcoat-oxidation of MCrAlY alloys

International Nuclear Information System (INIS)

Schmitt-Thomas, K.G.; Dietl, U.

1992-01-01

Under operating conditions in gas turbines plasma sprayed MCrAlY bondcoats (M = Co and/or Ni) for thermal barrier coatings are exposed to a strong oxidation attack. One possibility to reduce bondcoat oxidation is the application of diffusion barriers. Onto the bondcoat, diffusion barriers of Al 2 O 3 are deposited by CVD, PVD and plasma pulse process. The oxidation behaviour of these coating systems were examined at a temperature of 1273 K for times up to 250 hours. The CVD and PVD Al 2 O 3 - coated specimens show compared to the uncoated specimens smaller oxidation rates. The porous Al 2 O 3 coatings, produced by plasma pulse process are not fit for oxidation protection of the bondcoat. There is hope for further improvement of the oxidation resistance by optimizing the CVD- and PVD-process parameters. (orig.) [de

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

International Nuclear Information System (INIS)

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

1979-01-01

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

As-Deposited (La1-xSrx)(Ga1-y-zMgyCoz)O3-(x+y+z)/2 Crystallized Thin Films Prepared by Pulsed Laser Deposition for Application to Solid Oxide Fuel Cell Electrolyte

Science.gov (United States)

Mitsugi, Fumiaki; Kanazawa, Seiji; Ohkubo, Toshikazu; Nomoto, Yukiharu; Ishihara, Tatsumi; Takita, Yusaku

2004-01-01

Doped lanthanum gallate (La1-xSrx)(Ga1-y-zMgyCoz)O3-(x+y+z)/2 (LSGMCO) perovskite oxide films were deposited on a quartz glass, LaAlO3 single-crystal substrate and porous anode electrode of a solid oxide fuel cell (SOFC) by pulsed laser deposition. It was necessary to increase the substrate temperature up to 800°C for a crystallization of the LSGMCO films. The film deposited on the LaAlO3 single-crystal substrate grew along the c-axis. The as-deposited LSGMCO thick film fabricated on the porous substrate at 800°C and at an oxygen pressure of 20Pa was formed from polycrystal columns and showed a high conductivity of 0.7S/cm at a measurement temperature of 800°C. The activation energies were 0.72 eV at 600-800°C and 1.05 eV at 400-600°C.

(La, Pr)0.8Sr0.2FeO3-δ-Sm 0.2Ce0.8O2-δ composite cathode for proton-conducting solid oxide fuel cells

KAUST Repository

Chen, Yonghong

2014-08-01

Mixed rare-earth (La, Pr)0.8Sr0.2FeO 3-δ-Sm0.2Ce0.8O2-δ (LPSF-SDC) composite cathode was investigated for proton-conducting solid oxide fuel cells based on protonic BaZr0.1Ce0.7Y 0.2O3-δ (BZCY) electrolyte. The powders of La 0.8-xPrxSr0.2FeO3-δ (x = 0, 0.2, 0.4, 0.6), Sm0.2Ce0.8O2-δ (SDC) and BaZr0.1Ce0.7Y0.2O3-δ (BZCY) were synthesized by a citric acid-nitrates self-propagating combustion method. The XRD results indicate that La0.8-xPrxSr 0.2FeO3-δ samples calcined at 950 °C exhibit perovskite structure and there are no interactions between LPSF0.2 and SDC at 1100 °C. The average thermal expansion coefficient (TEC) of LPSF0.2-SDC, BZCY and NiO-BZCY is 12.50 × 10-6 K-1, 13.51 × 10-6 K-1 and 13.47 × 10-6 K -1, respectively, which can provide good thermal compatibility between electrodes and electrolyte. An anode-supported single cell of NiO-BZCY|BZCY|LPSF0.2-SDC was successfully fabricated and operated from 700 °C to 550 °C with humidified hydrogen (∼3% H2O) as fuel and the static air as oxidant. A high maximum power density of 488 mW cm -2, an open-circuit potential of 0.95 V, and a low electrode polarization resistance of 0.071 Ω cm2 were achieved at 700 °C. Preliminary results demonstrate that LPSF0.2-SDC composite is a promising cathode material for proton-conducting solid oxide fuel cells. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Improved dielectric properties and grain boundary response in neodymium-doped Y_2_/_3Cu_3Ti_4O_1_2 ceramics

International Nuclear Information System (INIS)

Liang, Pengfei; Yang, Zupei; Chao, Xiaolian

2016-01-01

Rare earth element neodymium was adopted to refine grain and in turn increase the volume of grain boundary of Y_2_/_3Cu_3Ti_4O_1_2 ceramics, which could strongly increase the resistance of grain boundary. Proper amount of Nd substitution in Y_2_/_3_−_xNd_xCu_3Ti_4O_1_2 ceramics could significantly depress the low-frequency dielectric loss. When the doping level is 0.06 and 0.09, the samples exhibited a relatively low dielectric loss (below 0.050 between 0.3 and 50 kHz) and high dielectric constant above 11000 over a wide frequency range from 40 Hz to 100 kHz. Based on the ε′-T plots, dielectric relaxation intensity was substantially weakened by Nd doping so that the temperature stability of dielectric constant was improved obviously. The correlations between low-frequency dielectric loss and the resistance of grain boundary were revealed. After Nd doping, the activation energies for the conduction behavior in grain boundaries were significantly enhanced, and the activation energies for the dielectric relaxation process in grain boundaries were slightly influenced. - Highlights: • Significant decrease in dielectric loss of Y_2_/_3_−_xNd_xCu_3Ti_4O_1_2 ceramics was realized. • The enhanced grain boundary density is responsible for the lowered dielectric loss. • Nd doping could improve the temperature stability of dielectric constant. • Oxygen vacancies contribute to conduction and relaxation process of grain boundaries.

A high performance BaZr0.1Ce0.7Y0.2O3-δ-based solid oxide fuel cell with a cobalt-free Ba0.5Sr0.5FeO3-δ–Ce0.8Sm0.2O2-δ composite cathode

NARCIS (Netherlands)

Sun, Wenping; Shi, Zhen; Fang, S.; Yan, Litao; Zhu, Zhiwen; Liu, Wei

2010-01-01

A cobalt-free Ba0.5Sr0.5FeO3-δ–Ce0.8Sm0.2O2-δ (BSF–SDC) composite is employed as a cathode for an anode-supported proton-conducting solid oxide fuel cells (H-SOFCs) using BaZr0.1Ce0.7Y0.2O3-δ (BZCY) as the electrolyte. The chemical compatibility between BSF and SDC is evaluated. The XRD results show

Luminescence properties of Nd3+-doped Y2O3 nanoparticles in organic media

International Nuclear Information System (INIS)

Cui, Xiaoxia; Hou, Chaoqi; Lu, Jiabao; Gao, Chao; Wei, Wei; Peng, Bo

2011-01-01

Nd 3+ -doped yttrium oxide nanoparticles (Y 2 O 3 :Nd) with cubic phase were obtained successfully by a glycine-nitrate solution combustion method. The results of Fourier transform infrared spectra (FTIR) showed that the -OH groups residing on the nanoparticles surfaces were reduced effectively by modifying with capping agent. The modified Y 2 O 3 :Nd nanoparticles displayed good monodispersity and excellent luminescence in N,N-dimethylformamide (DMF) solvent. Some optical parameters were calculated by Judd-Ofelt analysis based on absorption and fluorescence spectra. A relative large stimulated emission cross section, 1.7 x 10 -20 cm 2 , of the 4 F 3/2 → 4 I 11/2 transition was calculated. Theses results show that the modified Y 2 O 3 :Nd nanoparticles display good luminescence behavior in organic media. (orig.)

Ho3+/Yb3+ co-doped TeO2-BaF2-Y2O3 glasses for ∼1.2 μm laser applications

Science.gov (United States)

Wang, Shunbin; Li, Chengzhi; Yao, Chuanfei; Jia, Shijie; Jia, Zhixu; Qin, Guanshi; Qin, Weiping

2017-02-01

Intense ∼1.2 μm fluorescence is observed in Ho3+/Yb3+ co-doped TeO2-BaF2-Y2O3 glasses under 915 nm laser diode excitation. The 1.2 μm emission can be ascribed to the transition 5I6→5I8 of Ho3+. With the introducing of BaF2, the content of OH in the glasses drops markedly, and the 1.2 μm emission intensity increases gradually as increasing the concentration percentage of BaF2. Furthermore, microstructured fibers based on the TeO2-BaF2-Y2O3 glasses are fabricated by using a rod-in-tube method, and a relative positive gain of ∼9.42 dB at 1175.3 nm is obtained in a 5 cm long fiber.

Crossover from disordered to core-shell structures of nano-oxide Y{sub 2}O{sub 3} dispersed particles in Fe

Energy Technology Data Exchange (ETDEWEB)

Higgins, M. P.; Wang, L. M.; Gao, F., E-mail: gaofeium@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Lu, C. Y. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, Liaoning 110819 (China); Lu, Z. [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, Liaoning 110819 (China); Shao, L. [Department of Nuclear Engineering, Texas A& M University, College Station, Texas 77843 (United States)

2016-07-18

Molecular dynamic simulations of Y{sub 2}O{sub 3} in bcc Fe and transmission electron microscopy (TEM) observations were used to understand the structure of Y{sub 2}O{sub 3} nano-clusters in an oxide dispersion strengthened steel matrix. The study showed that Y{sub 2}O{sub 3} nano-clusters below 2 nm were completely disordered. Y{sub 2}O{sub 3} nano-clusters above 2 nm, however, form a core-shell structure, with a shell thickness of 0.5–0.7 nm that is independent of nano-cluster size. Y{sub 2}O{sub 3} nano-clusters were surrounded by off-lattice Fe atoms, further increasing the stability of these nano-clusters. TEM was used to corroborate our simulation results and showed a crossover from a disordered nano-cluster to a core-shell structure.

Structural and photoluminescence studies of pure and Eu3+ doped Y2O3 oxide nanoparticles

International Nuclear Information System (INIS)

Packiyaraj, P.; Thangadurai, P.

2013-01-01

Pure and Eu 3+ doped Y 2 O 3 nanoparticles were synthesized by a hydrolysis assisted co-precipitation method. Structural characterization was carried out by X-ray diffraction. The as-prepared Eu:Y 2 O 3 was amorphous yttrium hydroxides in nature and become crystalline Y 2 O 3 once annealed at 600℃ and 900℃. The particle size (13-23 nm) was dependent on annealing temperatures and Eu 3+ ion concentration. Photoluminescence studies showed weak emission bands at 581, 587, 593, and 599 nm, corresponding to the 5 D 0 → 7 F 1 transitions, and sharp peaks with a maximum intensity occurring at 611 nm, due to the 5 D 0 → 7 F 2 transitions of Eu 3+ . (author)

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

International Nuclear Information System (INIS)

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

1987-01-01

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

Anomalous Interface and Surface Strontium Segregation in (La 1– y Sr y ) 2 CoO 4±δ /La 1– x Sr x CoO 3−δ Heterostructured Thin Films

KAUST Repository

Feng, Zhenxing

2014-03-20

Heterostructured oxides have shown unusual electrochemical properties including enhanced catalytic activity, ion transport, and stability. In particular, it has been shown recently that the activity of oxygen electrocatalysis on the Ruddlesden-Popper/perovskite (La1-ySr y)2CoO4±δ/La1-xSr xCoO3-δ heterostructure is remarkably enhanced relative to the Ruddlesden-Popper and perovskite constituents. Here we report the first atomic-scale structure and composition of (La1-ySr y)2CoO4±δ/La1-xSr xCoO3-δ grown on SrTiO3. We observe anomalous strontium segregation from the perovskite to the interface and the Ruddlesden-Popper phase using direct X-ray methods as well as with ab initio calculations. Such Sr segregation occurred during the film growth, and no significant changes were found upon subsequent annealing in O2. Our findings provide insights into the design of highly active catalysts for oxygen electrocatalysis. © 2014 American Chemical Society.

Anomalous Interface and Surface Strontium Segregation in (La 1– y Sr y ) 2 CoO 4±δ /La 1– x Sr x CoO 3−δ Heterostructured Thin Films

KAUST Repository

Feng, Zhenxing; Yacoby, Yizhak; Gadre, Milind J.; Lee, Yueh-Lin; Hong, Wesley T.; Zhou, Hua; Biegalski, Michael D.; Christen, Hans M.; Adler, Stuart B.; Morgan, Dane; Shao-Horn, Yang

2014-01-01

Heterostructured oxides have shown unusual electrochemical properties including enhanced catalytic activity, ion transport, and stability. In particular, it has been shown recently that the activity of oxygen electrocatalysis on the Ruddlesden-Popper/perovskite (La1-ySr y)2CoO4±δ/La1-xSr xCoO3-δ heterostructure is remarkably enhanced relative to the Ruddlesden-Popper and perovskite constituents. Here we report the first atomic-scale structure and composition of (La1-ySr y)2CoO4±δ/La1-xSr xCoO3-δ grown on SrTiO3. We observe anomalous strontium segregation from the perovskite to the interface and the Ruddlesden-Popper phase using direct X-ray methods as well as with ab initio calculations. Such Sr segregation occurred during the film growth, and no significant changes were found upon subsequent annealing in O2. Our findings provide insights into the design of highly active catalysts for oxygen electrocatalysis. © 2014 American Chemical Society.

Rare earth oxide doping in oxide cathodes

International Nuclear Information System (INIS)

Engelsen, Daniel den; Gaertner, Georg

2006-01-01

The effect on life performance and poisoning with O 2 by doping oxide cathodes with rare earth oxides and pseudo rare earth oxides, notably yttria, is qualitatively explained in terms of electrolysis of BaO during emission of electrons. Doped cathodes show less electrolysis and consume therefore less Ba during life: consequently, doped cathodes have a better life performance. However, the lower Ba-production makes doped cathodes more sensitive to oxygen poisoning. The experimentally found relation between conductivity and yttria concentration was the motive to propose a new model for the crystal imperfections in BaO. In this new imperfection model most Y 3+ -ions will combine with barium vacancies, therefore, the increase of the conductivity is modest and also the effect on the position of the Fermi level is modest. By assuming a combination of bulk and surface conductivity, the agreement between experiment and theory can be improved further

Formation of Y{sub x}Nd{sub 1-x}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} (0{<=}x{<=}0.9) superconductors from an undercooled melt via aero-acoustic levitation

Energy Technology Data Exchange (ETDEWEB)

Gustafson, D.E.; Hofmeister, W.H.; Bayuzick, R.J.; Nagashio, K.; Kuribayashi, K

2003-01-20

This paper presents the results of rapid solidification experiments performed on the copper oxide superconductors Y{sub x}Nd{sub 1-x}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} (0{<=}x{<=}0.9). Spherical rare earth (RE) 123 specimens were levitated in O{sub 2} using aero-acoustic levitation (AAL), melted with a laser, undercooled, and solidified. The peritectic transformation temperature for the reaction RE{sub 2}BaCuO{sub 5}+liquid{yields}REBa{sub 2}Cu{sub 3}O{sub 7-{delta}} corresponding to the maximum recalescence temperature during solidification was determined. RE123 was formed directly from the melt for Y-Nd binary alloy compositions with Nd concentration greater than 20% (Y concentration less than 80%). A minimum in the peritectic transformation temperature for the Nd/Y123 system corresponding to a composition Y{sub 0.3}Nd{sub 0.7}123 was determined at 66 deg. C below the peritectic of pure Nd123.

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

International Nuclear Information System (INIS)

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

2010-01-01

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

Influence of rare earth additions on the oxidation resistance of chromia forming alloys

International Nuclear Information System (INIS)

Pillis, Marina Fuser

1995-01-01

The addition of rare earths to alloys, either in elemental form or as surface coatings reduces the oxidation rate of chromia forming alloys. The rare earths either act as nucleation sites for surface oxides or get incorporates into the surface oxide and diffuse to oxide grain boundaries. If the latter occurs, a change in the defect structure close to the grain boundaries, probably takes place. In this manner, the rare earths inhibits the movement of chromium ions to the oxide/gas interface. The influence of rare earth additions to AISI 316, AISI 316L and Ni-20 Cr on their oxidation behavior has been studied., AISI 316+Ce, AISI 316+Y, Ni-20 Cr and Ni-20 Cr-2 Al-1 Ce were prepared by melting and AISI 316L, AISI 316L+Ce O 2 and AISI 316L+Y 2 O 3 by powder compaction. The effect of superficial deposits of rare earth oxides was also studied. The alloys were coated with rare earth oxides by high temperature conversion of the respective rare earth nitrates. Isothermal oxidation tests were carried out at 900-1100 deg C and the cyclic oxidation tests consisted of 6 cycles of 2 hours each at 900 deg C, followed by cooling to room temperature. All the tests were carried out in air. Oxidation behavior was evaluated gravimetrically. Scanning electron microscopy was used to study surface morphology. Energy dispersive analysis and X-ray diffraction techniques were used to identify oxide constituents. Overall, it has been observed that with the addition of rare earths, oxidation resistance increases by decreasing oxidation rates and increasing oxide adhesion. Addition of rare earths to AISI 316 prepared by melting resulted in rapid formation of a chromium rich oxide layered near the metal/oxide interface which reduced overall oxidation rate. The addition of Ce O 2 to AISI 316L was found to improve oxidation behavior after 10 hours at 1100 deg C and also inhibit the formation of volatile Cr O 3 . The isothermal oxidation behavior of rare earth oxide covered Ni-20 Cr at 900 deg C

Dependence of glass-forming ability on starting compositions in Y2O3–Al2O3–SiO2 system

Directory of Open Access Journals (Sweden)

Yixiang Chen

2011-09-01

Full Text Available The dependence of glass-forming ability on starting compositions in Y2O3–Al2O3–SiO2 (YAS system has been investigated by melting experiment. Transparent YAS glasses have been prepared under the condition of furnace cooling instead of quenching. It is found that, in the YAS ternary phase diagram, the compositions on the Y3Al5O12–SiO2 line and with 52-68 mol% SiO2 have a higher glass-forming ability to produce pure glass. For the compositions with too much or less SiO2 or with Y/Al = 5/3, 1/1, or 1/3, crystallization occurs with the formation of Y3Al5O12, Y2Si2O7, Al6Si2O13, or SiO2. The densities of the YAS glasses increase with decreasing SiO2 contents and increasing Y/Al ratios, and for the samples with Y/Al = 3/5 there is a good linear relationship between the density and SiO2 content.

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

International Nuclear Information System (INIS)

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

2006-01-01

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

Al{sub 2}O{sub 3} reinforced nanoparticle ZrO{sub 2} (3at%?Y{sub 2}O{sub 3}); Al{sub 2}O{sub 3} reforcado com nanoparticulas de ZrO{sub 2}(3%mol Y{sub 2}O{sub 3})

Energy Technology Data Exchange (ETDEWEB)

Cossu, C.M.F.A.; Alves, M.F.R.P.; Campos, L.Q.B.; Magnago, R.O.; Santos, C., E-mail: caio.cossu@usp.br [Universidade do Estado do Rio de Janeiro (UERJ), Resende, RJ (Brazil). Faculdade de Tecnologia; Simba, B.G. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Guaratingueta, SP (Brazil). Faculdade de Engenharia

2016-07-01

This work developed a composite Al{sub 2}O{sub 3}-based reinforced with nanoparticles of ZrO{sub 2} (Y{sub 2}O{sub 3}), to evaluate the effect of the content of ZrO{sub 2} nanoparticles (Y{sub 2}O{sub 3}) on the mechanical properties. Mixtures containing a matrix of Al{sub 2}O{sub 3} with fractions in weight of 3%, 5%, 10% and 15%, ZrO{sub 2} (Y{sub 2}O{sub 3}), and were mixed in mortar mill. Mixtures received 5% polymeric binder (PVA); and after adding the binder, the material was pressed uniaxially to 50MPa, and then sintered at a temperature of 1600 ° C - 2h. The sintered products were characterized by X-ray diffraction, scanning electron microscopy (SEM), relative density, hardness and fracture toughness. The results of X-ray diffraction showed that Al{sub 2}O{sub 3} and tetragonal ZrO{sub 2} as crystal phases found after sintering. Furthermore, the relative green density of 55% was predominant in the compact; and after sintering, varied depending on the ZrO{sub 2} content, reaching 97% in sintered compositions with 3% ZrO{sub 2} nanoparticles (Y{sub 2O}3). The hardness of the samples showed values of 1670HV and the maximum toughness of 3.2 MPa × m{sup 1/2}, directly influenced by the presence of nanoparticles ZrO{sub 2} uniformly dispersed in the matrix Al{sub 2}O{sub 3}, which results in at least two main mechanisms tenacifiers: transformation of tetragonal-monoclinic phase of zirconia, and compressive residual strain between the two phases present, Al{sub 2}O{sub 3} and tetragonal ZrO{sub 2}. (author)

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

Science.gov (United States)

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

2018-05-01

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

Superconducting transition temperature in the Y(1-x)M(x)Ba2Cu3O(y) system

Science.gov (United States)

Suzuki, Takeyuki; Yamazaki, Tsutomu; Sekine, Ryuuta; Koukitsu, Akinori; Seki, Hisashi

1989-04-01

Experimental results are presented for the inclusion of compositional additives, M, to the sintered high-temperature superconductor Y(1-x)M(x)Ba2Cu3O(y); M can be the oxides of Mg, Ce, Gd, Yb, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Zn, B, Al, Ga, In, Si, Ge, Sn, Pb, Sb, Bi, and Te, as well as Li, Na, K, Ca, Sr, and La carbonates. Temperature dependence of the electrical resistance was measured down to about 80 K. Attention is given to the influence of ionic radius and the valence of the M species.

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

Science.gov (United States)

Huang, Shengxuan; Wu, Xiang; Qin, Shan

2018-01-10

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

Nonlinear acoustic properties of the ternary (La sub 2 O sub 3) sub x (Sm sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) phosphate glasses

International Nuclear Information System (INIS)

Senin, H.B.; Sidek, H.A.A.; Saunders, G.A.

1994-01-01

From measurements of changes in transit time of 10 MHz of ultrasonic wave as a function of temperature and hydrostatic pressure, the linear and non-linear acoustic properties of the ternary (La sub 2 O sub 3) sub x (Sm sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses with compositions near to that corresponding to the metaphosphate have been determined. For each glass the second order elastic stiffness tensor components C sub ijs (SOEC) continue to increase down to 10K in a manner consistent with phonons interactions with two level systems. Measurements of the effects of hydrostatic pressure on the ultrasonic wave velocities have been used to determine the hydrostatic pressure derivatives (dC sub ij/dP) sub T,P=0 of the SOEC and (dB0 sup s)/dP) sub T,P=0 of the bulk modulus B0 sup s at room temperature (293K). For the ternary (La sub 2 O sub 3) sub x (Sm sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses, (dC sub 11/dP), (dC sub 44/dP), and (dBo/dP), are small but positives; these glasses stiffen under pressure. The elastic behaviour of these ternary glasses lies intermediate between those of (Sm sub 2 O sub 3)(P sub 2 O sub 5) sub (1-x) and (La sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses. Replacement of the Sm sup 3+ by La sup 3+ in the ternary phosphate glasses negates the acoustic mode softening. Possible sources of the different effects of La sub 3+ and Sm sub 3+ modifiers on the nonlinear acoustic properties of metaphosphate glasses are discussed

Effects of Y2O3 upon mechanical properties of laser coating

Institute of Scientific and Technical Information of China (English)

Chi Deng; Yong Wang; Yaping Zhang; Jiacheng Gao

2005-01-01

@@ Roles of Y2O3 in mechanical properties of the bioceramic coating by the laser cladding were reported in this paper. The bonding strength of interface between the laser coatings with/without Y2O3 and substrate Ti-6Al-4V (TC4), bending strength, compressive strength, tensile strength, and hardness in these coatings were contrastively tested, and the ceramic-metal interface was observed by scanning electronic microscopy (SEM). These results indicated that the rare earth was the important factor which influenced the mechanical properties of the coating. Y2O3 was adequately dispersed in the melting pool of the laser coating, crystal grain got smaller after the melted coating was cooled, the impurity existing in crystal interface was reduced by chemical reactions, and so the strength was evidently improved. On the other hand, the rare earth could also obviously increase the hole numbers in the coating and decrease the compressive strength. So the effects of the rare earth on the laser coating were intricate and all-purpose.

Direct laser writing of superconducting patterns of Y1Ba2Cu3O/sub 7-//sub δ/

International Nuclear Information System (INIS)

Gupta, A.; Koren, G.

1988-01-01

Direct argon ion laser writing of 40-μm-wide and 3-μm-thick superconducting lines of Y 1 Ba 2 Cu 3 O/sub 7-//sub δ/ on magnesium oxide (MgO) substrate is reported. A 514.5 nm laser beam of 300 mW was focused onto a thin sprayed film of the nitrate precursors (Y:Ba:Cu = 1:2:3) and scanned over it. The laser beam converted oxides along the irradiation path. The film was then ''developed'' by rinsing it in ethanol, which removed the unirradiated areas, but left the irradiated areas intact. This was followed by the standard oven annealing procedure in flowing oxygen. The resistivity of the laser-written lines as a function of temperature showed an onset and completion of the superconducting transition at 82 and 69 K, respectively. The corresponding values of the unpatterned, blanket film were 82 and 77 K, respectively

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

International Nuclear Information System (INIS)

De Crom, N.; Devillers, M.

2012-01-01

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

Red, yellow, blue and green emission from Eu3+, Dy3+ and Bi3+ doped Y2O3 nanophosphors

International Nuclear Information System (INIS)

Loitongbam, Romeo Singh; Rameshwor Singh, W.

2014-01-01

Rare earth elements (RE = Eu 3+ and Dy 3+ ) and Bi 3+ doped Y 2 O 3 nanoparticles were synthesized by urea hydrolysis method in ethylene glycol, which acts as reaction medium as well as capping agent, at a low temperature (140℃), followed by calcination of the obtained product. Scanning electron microscopy (SEM) images reveal that a highly uniform ovoid shaped Y 2 O 3 nanoparticles of around 100 nm size range were obtained in this method. The respective RE and Bi 3+ doped Y 2 O 3 precursor nanoparticles when heated at 600 and 750℃, retains the same shape as that of the as-synthesized Y 2 O 3 precursor samples. XRD pattern reveals the crystalline nature of the heated nanoparticles and indicate the absence of any impurity phase other than cubic Y 2 O 3

Fundamental absorption of Y2O3 and YAlO3

International Nuclear Information System (INIS)

Abramov, V.N.; Kuznetsov, A.I.

1978-01-01

Reflection spectra in the range of 4-14 eV were measured for Y 2 O 3 and YAlO 3 crystals. The spectra of the following optical characteristics were calculated with the aid of the Kramers-Kroning relation: absorption, refraction, dielectric constant, and effective number of electrons. Excitons with an energy of 6.0 eV and an oscillator strength of f approximately 0.1 were found in Y 2 O 3 , and the width of the forbidden zone was determined (approximately 6.1 eV). The scheme of genealogy and arrangement of the plane zones of Y 2 O 3 , in which a substantial role is attributed to interaction of 5s and 4d states of yttrium cations, is proposed and discussed at the qualitative level. The range of the beginning of fundamental absorption (hν > or approximately 7.5 eV) was determined for YAlO 3 . The composition dependence of the width of the forbidden zone of aluminated Ysub(x)Alsub(y)Osub(z) is plotted

Thermodynamic modeling of La2O3-SrO-Mn2O3-Cr2O3 for solid oxide fuel cell applications

DEFF Research Database (Denmark)

Povoden-Karadeniz, E.; Chen, Ming; Ivas, Toni

2012-01-01

The thermodynamic La–Sr–Mn–Cr–O oxide database is obtained as an extension of thermodynamic descriptions of oxide subsystems using the calculation of phase diagrams approach. Concepts of the thermodynamic modeling of solid oxide phases are discussed. Gibbs energy functions of SrCrO4, Sr2.67Cr2O8......, Sr2CrO4, and SrCr2O4 are presented, and thermodynamic model parameters of La–Sr–Mn–Chromite perovskite are given. Experimental solid solubilities and nonstoichiometries in La1xSrxCrO3d and LaMn1xCrxO3d are reproduced by the model. The presented oxide database can be used for applied computational...... thermodynamics of traditional lanthanum manganite cathode with Cr-impurities. It represents the fundament for extensions to higher orders, aiming on thermodynamic calculations in noble symmetric solid oxide fuel cells...

Nanostructured Y2O3

International Nuclear Information System (INIS)

Skandan, G.; Hahn, H.; Parker, J.C.

1991-01-01

It has been shown that a variety of nanostructured (n-) metal-oxide ceramics such as n-TiO 2 , n-ZrO 2 , n-Al 2 O 3 , n-ZnO and n-MgO can be produced using the inert gas condensation process. Amongst all the nanostructured oxides, the synthesis, microstructure, sintering, and mechanical properties of n-TiO 2 have been studied the most extensively. The gas condensation preparation of nanostructured metal-oxide ceramics involves evaporation of metal nanoparticles, collection and post- oxidation. The original synthesis studies of n-TiO 2 showed that in order to avoid formation of the many low oxidation state oxides in the Ti-O system, the post-oxidation had to be performed by rapidly exposing the Ti nanoparticles to pure oxygen gas. By doing so, the highest oxidation state and the most stable structure, rutile, was obtained. An undesired feature of this step is that the nanoparticles heat up to high temperatures for a brief period of time due to the exothermic nature of the oxidation. As a consequence, the particles with an average size of 12 nm tend to agglomerate into larger structures up to 50 nm. The agglomerated state of the powder is important since it determines the original density and pore size distribution after compaction, as well as the sintering characteristics and final microstructure of the bulk sample. As a consequence of the preparation procedure of n-TiO 2 and the resulting agglomeration, the pore size distribution of n-TiO 2 compacted at room temperature is very wide, with pore sizes ranging from 1 to 200 nm. Nevertheless, the n-TiO 2 sinters at temperatures several hundred degrees lower than conventional coarse grained ceramics. From the previous results on n- TiO 2 it is anticipated that better microstructures and properties can be achieved by reducing the agglomeration of nanostructured powders through a more controlled post- oxidation process

Tunable thermodynamic activity of La x Sr1-x Mn y Al1-y O3-δ (0 ≤ x ≤ 1, 0 ≤ y ≤ 1) perovskites for solar thermochemical fuel synthesis.

Science.gov (United States)

Ezbiri, M; Takacs, M; Theiler, D; Michalsky, R; Steinfeld, A

2017-02-28

Nonstoichiometric metal oxides with variable valence are attractive redox materials for thermochemical and electrochemical fuel processing. To guide the design of advanced redox materials for solar-driven splitting of CO 2 and/or H 2 O to produce CO and/or H 2 (syngas), we investigate the equilibrium thermodynamics of the La x Sr 1- x Mn y Al 1- y O 3- δ perovskite family (0 ≤ x ≤ 1, 0 ≤ y ≤ 1) and La 0.6 Ca 0.4 Mn 0.8 Al 0.2 O 3- δ , and compare them to those of CeO 2 as the baseline. Oxygen nonstoichiometry measurements from 1573 to 1773 K and from 0.206 to 180 mbar O 2 show a tunable reduction extent, increasing with increasing Sr content. Maximal nonstoichiometry of 0.32 is established with La 0.2 Sr 0.8 Mn 0.8 Al 0.2 O 3- δ at 1773 K and 2.37 mbar O 2 . As a trend, we find that oxygen capacities are most sensitive to the A-cation composition. Partial molar enthalpy, entropy and Gibbs free energy changes for oxide reduction are extracted from the experimental data using defect models for Mn 4+ /Mn 3+ and Mn 3+ /Mn 2+ redox couples. We find that perovskites exhibit typically decreasing enthalpy changes with increasing nonstoichiometries. This desirable characteristic is most pronounced by La 0.6 Sr 0.4 Mn 0.4 Al 0.6 O 3- δ , rendering it attractive for CO 2 and H 2 O splitting. Generally, perovskites show lower enthalpy and entropy changes than ceria, resulting in more favorable reduction but less favorable oxidation equilibria. The energy penalties due to larger temperature swings and excess oxidants are discussed in particular. Using electronic structure theory, we conclude with a practical methodology estimating thermodynamic activity to rationally design perovskites with variable stoichiometry and valence.

Simultaneous determination of dysprosium, holmium and erbium in high purity rare earth oxides by second order derivative spectrophotometry

International Nuclear Information System (INIS)

Anbu, M.; Prasada Rao, T.; Iyer, C. S. P.; Damodaran, A. D.

1996-01-01

High purity individual rare earth oxides are increasingly used as major components in lasers (Y 2 O 3 ), phosphors (YVO 3 , Eu 2 O 3 ), magnetic bubble memory films (Gd 2 O 3 ) and refractive-index lenses and fibre optics (La 2 O 3 ). The determination of individual lanthanides in high purity rare earth oxides is a more important and difficult task. This paper reports the utilization of higher order derivative spectrophotometry for the simultaneous determination of dysprosium, holmium and erbium in high purity rare earth oxides. The developed procedure is simple, reliable and allows the determination of 0.001 to 0.2% of dysprosium, holmium and erbium in several rare earth. (author). 9 refs, 2 figs, 2 tabs

The performance of Y2O3 as interface layer between La2O3 and p-type silicon substrate

Directory of Open Access Journals (Sweden)

Shulong Wang

2016-11-01

Full Text Available In this study, the performance of Y2O3 as interface layer between La2O3 and p-type silicon substrate is studied with the help of atomic layer deposition (ALD and magnetron sputtering technology. The surface morphology of the bilayer films with different structures are observed after rapid thermal annealing (RTA by atomic force microscopy (AFM. The results show that Y2O3/Al2O3/Si structure has a larger number of small spikes on the surface and its surface roughness is worse than Al2O3/Y2O3/Si structure. The reason is that the density of Si substrate surface is much higher than that of ALD growth Al2O3. With the help of high-frequency capacitance-voltage(C-V measurement and conductivity method, the density of interface traps can be calculated. After a high temperature annealing, the metal silicate will generate at the substrate interface and result in silicon dangling bond and interface trap charge, which has been improved by X-ray photoelectron spectroscopy (XPS and interface trap charge density calculation. The interface trapped charge density of La2O3/Al2O3/Si stacked gate structure is lower than that of La2O3/Y2O3/Si gate structure. If Y2O3 is used to replace Al2O3 as the interfacial layer, the accumulation capacitance will increase obviously, which means lower equivalent oxide thickness (EOT. Our results show that interface layer Y2O3 grown by magnetron sputtering can effectively ensure the interface traps near the substrate at relative small level while maintain a relative higher dielectric constant than Al2O3.

Study of Pt–Rh/CeO2–ZrO2–MxOy (M = Y, La)/Al2O3 three-way catalysts

International Nuclear Information System (INIS)

Jiaxiu, Guo; Zhonghua, Shi; Dongdong, Wu; Huaqiang, Yin; Maochu, Gong; Yaoqiang, Chen

2013-01-01

CeO 2 –ZrO 2 –M x O y (M = Y; La) mixed oxides, prepared by co-precipitation method and characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Raman spectra (RM) and oxygen pulse reaction, were comparatively investigated to elucidate the combinational effects of Y and/or La oxide promoters on the catalytic activity and anti-aging performance of monolithic cordierite honeycomb catalysts with low Pt and Rh content. The catalytic activities, water-gas shift (WGS) and steam reforming reaction (SR) were studied under a simulated gas mixture. The catalysts were also characterized by H 2 -temperature-programmed reduction (H 2 -TPR) and O 2 -temperature-programmed desorption (O 2 -TPD). The results showed that the prepared CeO 2 –ZrO 2 –M x O y oxides have a face-centered cubic fluorite structure and are nanosize. La 3+ ions can significantly improve thermal stability and efficiently retard CeO 2 –ZrO 2 crystal sintering and growth. Doped CeO 2 –ZrO 2 with Y 3+ and La 3+ has 105 and 60 m 2 /g surface area and 460 and 390 μmol/g OSC before and after aging. The T 50 of fresh Pt–Rh/CZYL/LA is 170 °C for CO, 222 °C for C 3 H 8 and 189 °C for NO, and shift to 205, 262 and 228 °C after hydrothermal aging, which are better than those of Pt–Rh/CZY/LA or Pt–Rh/CZL/LA. WGS and SR are relate to the OSC of oxygen storage materials and absorbed oxygen species on the catalyst surface and affect the three-way catalytic activities of catalysts. The reductive property of noble metals and the dissociatively adsorbed O 2 on the surface of catalysts are closely related to the catalytic activities.

Effect of rare-earth composition on microstructure and pinning properties of Zr-doped (Gd, Y)Ba{sub 2}Cu{sub 3}O{subx} superconducting tapes.

Energy Technology Data Exchange (ETDEWEB)

Selvamanickam, V.; Chen, Y.; Zhang, Y.; Guevara, A.; Shi, T.; Yao, Y.; Majkic, G.; Lei, C.; Galtsyan, E.; Miller, D. J. (Materials Science Division); (Univ. Houston); (SuperPower Inc.)

2012-01-01

The effect of changing Gd + Y content from 1.2 to 1.6 in the precursor of (Gd,Y)Ba{sub 2}Cu{sub 3}O{sub 7} superconducting thin film tapes made by metal organic chemical vapor deposition (MOCVD) at a constant Gd:Y ratio and a fixed Zr content of 7.5% has been studied. The influence of changing the Gd:Y ratio from Gd = 0 to Y= 0 in 0.2 mol steps at a constant Gd + Y content of 1.2 in the precursor has also been investigated at a fixed Zr content of 7.5%. The critical current of these films is found to vary significantly as a function of rare-earth content as well as a function of rare-earth type. Even for a fixed Zr content, it is found that the critical current in the orientation of magnetic field parallel to the a-b plane and that in the orientation of field perpendicular to the a-b plane can be systematically varied with changing Gd + Y content as well as with changing Gd:Y ratio. The nanoscale defect structures along the a-b plane and along the c-axis are found to be sensitive to these changes in rare-earth content and type.

Characteristics of Sr0.92Y0.08Ti1-yNiyO3-δ anode and Ni-infiltrated Sr0.92Y0.08TiO3-δ anode using CH4 fuel in solid oxide fuel cells

Science.gov (United States)

Park, Eun Kyoung; Lee, Soonil; Yun, Jeong Woo

2018-01-01

Strontium titanium oxide co-doped with yttrium and nickel (SrxY1-xTiyNi1-yO3-δ; hereafter, SYTN), was investigated as an alternative anode material for solid oxide fuel cells. To improve the ionic conductivity of the Sr0.92Y0.08TiO3-δ (SYT) anode, Ni2+ was substituted into the B-site (initially occupied by Ti4+), thereby forming oxygen vacancies. To analyze the effects of Ni-doping in the SYT anode, the electrochemical properties of the SYTN anode were compared with those of the Ni-infiltrated SYT(Ni@SYT) using H2 and CH4 as fuels. The electrochemical reactions at the SYTN anode in the presence of both H2 and CH4 were limited by relatively slow reactions, such as non-charged processes including oxygen surface exchange and solid surface diffusion. The high electrical conductivity and excellent catalytic activity of the Ni nanoparticles in the Ni@SYT anode led to improved cell performance. CH4 decomposition at the Ni@SYT anode occurred via thermal pyrolysis of CH4 rather than by steam methane reforming, resulting in carbon deposition. In comparison, the poor inherent catalytic activity for CH4 oxidation exhibited by the SYTN anode minimized carbon deposition on the anode surface.

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

Energy Technology Data Exchange (ETDEWEB)

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

2012-07-01

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

Study of directionally solidified eutectic Al2O3-ZrO2(3%Y2O3 doped with TiO2

Directory of Open Access Journals (Sweden)

Peña, J. I.

2007-06-01

Full Text Available An study of directionally grown samples of the eutectic composition in the Al2O3-ZrO2 (3 mol% Y2O3 system, with small TiO2 additions (1 wt%, is presented. The microstructural changes induced by this addition are analysed using SEM (EDX techniques. The mechanical changes, when TiO2 is added, are studied by measuring the flexural strength by three point bending. Also, the toughness is determined by Vickers indentation method. When slow growth rates (10 mm/h are used, interpenetratred and homogeneous microstructure is obtained, independently of the TiO2 doping. When growth rates are higher (300 and 1000 mm/h the structure changes and the phases are organized in form of colonies or cells, which have smaller size when TiO2 is present. This size reduction is accompanied with an increase of the toughness.Este trabajo presenta un estudio de muestras crecidas direccionalmente del sistema Al2O3-ZrO2 (3 mol% Y2O3 en su composición eutéctica con pequeñas adiciones de óxido de titanio (1% de TiO2 en peso. Se analizan los cambios microestructurales inducidos por esta adición mediante SEM (EDX y se estudian los cambios en su comportamiento mecánico medido por flexión en tres puntos, así como la tenacidad de fractura mediante indentación Vickers. Con velocidades lentas de solidificación (10 mm/h se obtiene en ambos casos una microestructura homogénea e interpenetrada, mientras que a velocidades mayores, 300 y 1000 mm/h, se forma una estructura en las que las fases se organizan en forma de colonias o células, siendo éstas de menor tamaño en las muestras dopadas. Esta disminución en el tamaño viene acompañada de un aumento de la tenacidad de fractura medida por indentación.

Oxidation of 1-butene over uranium oxide (UO3)-antimony oxide (Sb2O3) catalysts

NARCIS (Netherlands)

Simons, T.; Houtman, P.N.; Schuit, G.C.A.

1971-01-01

The oxidative dehydrogenation of butene to butadiene over U-Sb catalysts was investigated. The presence of two compds., (UO2)Sb3O7 and Sb3U3O14, reported by Grasselli and Callahan (1969), was confirmed with (UO2)Sb3O7 being the actual catalyst. The reaction is first order in butene and zero order in

Size Determination of Y2O3 Crystallites in MgO Composite Using Mie Scattering

Science.gov (United States)

2017-11-07

embedded in a magnesium oxide (MgO) polycrystalline matrix. The calculation takes into account the volume fraction of Y2O3 in MgO, the average...release; distribution is unlimited. v Acknowledgments We gratefully acknowledge the financial support from the US Army Research Laboratory (ARL... principle , and the percent of theoretical density (TD) was calculated based on a TD of the mixture being 3.616 g/cm3. Table 1 Sample preparation

Electric Properties of Pb(Sb1/2Nb1/2)O3 PbTiO3 PbZrO3 Ceramics

Science.gov (United States)

Kawamura, Yasushi; Ohuchi, Hiromu

1994-09-01

Solid-solution ceramics of ternary system xPb(Sb1/2Nb1/2)O3 yPbTiO3 zPbZrO3 were prepared by the solid-state reaction of powder materials. Ceramic, electric, dielectric and piezoelectric properties and crystal structures of the system were studied. Sintering of the system xPb(Sb1/2Nb1/2)O3 yPbTiO3 zPbZrO3 is much easier than that of each end composition, and well-sintered high-density ceramics were obtained for the compositions near the morphotropic transformation. Piezoelectric ceramics with high relative dielectric constants, high radial coupling coefficient and low resonant resistance were obtained for the composition near the morphotropic transformation. The composition Pb(Sb1/2Nb1/2)0.075Ti0.45Zr0.475O3 showed the highest dielectric constant (ɛr=1690), and the composition Pb(Sb1/2Nb1/2)0.05Ti0.45Zr0.5O3 showed the highest radial coupling coefficient (kp=64%).

Preparation of layered oxide Li(Co1/3Ni1/3Mn1/3)O2 via the sol-gel process

Institute of Scientific and Technical Information of China (English)

ZHANG Wen; LIU Hanxing; HU Chen; ZHU Xianjun; LI Yanxi

2008-01-01

To obtain homogenous layered oxide Li(Co1/3Ni1/3Ni1/3Mn1/3)O2 as a lithium insertion positive electrode material,the sol-gel process using citric acid as a chelating agent was applied.The material Li(Co1/3,Ni1/3Mn1/3)O2 was synthesized at different calcination temperatures.XRD experiment indicated that the hyered Li(Co1/3Ni1/3Mn1/3)O2material could he synthesized at a lower temperature of 800℃,and the oxidation state of Co,Ni,and Mn in the cathode confirmed by XPS were +3,+2,and +4,respectively.SEM observations showed that the synthesized material could form homogenous particle morphology with the particle size of about 200nm In spite of different calcination temperatures,the charge-discharge curves of all the samples for the initial cycle were similar,and the cathode synthesized at 900℃ showed a small irreversible capacity loss of 11.24% and a high discharge capacity of 212.2 mAh.g-1 in the voltage range of 2.9-4.6 V.

Directed laser processing of compacted powder mixtures Al2O3-TiO2-Y2O3

Directory of Open Access Journals (Sweden)

Vlasova M.

2013-01-01

Full Text Available The phase formation, microstructure and surface texture of laser treated ternary powder mixtures of Al2O3-TiO2-Y2O3 had been studied. Rapid high temperature heating and subsequent rapid cooling due to the directed movement of the laser beam forms concave ceramic tracks. Phase composition and microstructure of the tracks depends on the Al2O3 content and the TiO2/Y2O3 ratio of the initial mixtures. The main phases observed are Y3Al5O12, Y2Ti2O7, Al2O3 and Al2TiO5. Due to the temperature gradient in the heating zone, complex layered structures are formed. The tracks consist of three main layers: a thin surface layer, a layer of crystallization products of eutectic alloys, and a lower sintered layer. The thickness of the crystallization layer and the shrinkage of the irradiation zone depend on the amount of Y3Al5O12 and Al2O3 crystallized from the melt.

Room temperature chemically oxidized La2CuO4+y: Phase separation induced by thermal treatment

DEFF Research Database (Denmark)

Rial,C.; Moran, E.; Alario-Franco, M.A.

1997-01-01

The structure of roam temperature chemically oxidized La2CuO4+y [y = 0.103(4)] has been refined from powder neutron diffraction data using the space group Bmab. The modifications induced in the CuO2 and the LaO planes by the insertion of oxygen are consistent with the high T-c measured for this m......The structure of roam temperature chemically oxidized La2CuO4+y [y = 0.103(4)] has been refined from powder neutron diffraction data using the space group Bmab. The modifications induced in the CuO2 and the LaO planes by the insertion of oxygen are consistent with the high T-c measured...... a short treatment at 433 K, La2CuO4.103(4) undergoes a phase separation into two phases: phase 1, with estimated y(1) = 0.086(4) and T-cl = 30 K, and phase 2, with estimated y(2) = 0.12(1) and T-c2 = 17 K. By increasing the annealing times, phase 2 transforms to phase I and finally disappears. Therefore...

Compatibility of yttria (Y{sub 2}O{sub 3}) with liquid lithium

Energy Technology Data Exchange (ETDEWEB)

Mitsuyama, Takaaki; Yoneoka, Toshiaki; Terai, Takayuki; Tanaka, Satoru [Tokyo Univ. (Japan). Faculty of Engineering

1996-10-01

Compatibility of Y{sub 2}O{sub 3} sintered specimens with liquid lithium was tested at 773K. No configuration change was observed with a slight increase of thickness for 1419 hr. Lithium-yttrium complex oxide (LiYO{sub 2}) was formed on the surface, and the inner part changed to gray or black nonstoichiometric Y{sub 2}O{sub 3-X} with lower electrical resistibility. It is concluded that Y{sub 2}O{sub 3} has a possibility as a ceramic coating material for liquid blankets if it can be made into a dense coating on the surface of piping materials. (author)

Resolution of 1-n-butyl-3-methyl-3-phospholene 1-oxide with TADDOL derivatives and calcium salts of O,O'-Dibenzoyl-(2R,3R)- or O,O'-di-p-toluoyl-(2R,3R)-tartaric acid.

Science.gov (United States)

Bagi, Péter; Fekete, András; Kállay, Mihály; Hessz, Dóra; Kubinyi, Miklós; Holczbauer, Tamás; Czugler, Mátyás; Fogassy, Elemér; Keglevich, György

2014-03-01

The resolution methods applying (-)-(4R,5R)-4,5-bis(diphenylhydroxymethyl)-2,2-dimethyldioxolane ("TADDOL"), (-)-(2R,3R)-α,α,α',α'-tetraphenyl-1,4-dioxaspiro[4.5]decan-2,3-dimethanol ("spiro-TADDOL"), as well as the acidic and neutral Ca(2+) salts of (-)-O,O'-dibenzoyl- and (-)-O,O'-di-p-toluoyl-(2R,3R)-tartaric acid were extended for the preparation of 1-n-butyl-3-methyl-3-phospholene 1-oxide in optically active form. In one case, the intermediate diastereomeric complex could be identified by single-crystal X-ray analysis. The absolute P-configuration of the enantiomers of the phospholene oxide was also determined by comparing the experimentally obtained and calculated CD spectra. © 2014 Wiley Periodicals, Inc.

Hydrothermal-precipitation preparation of CdS@(Er3+:Y3Al5O12/ZrO2) coated composite and sonocatalytic degradation of caffeine.

Science.gov (United States)

Huang, Yingying; Wang, Guowei; Zhang, Hongbo; Li, Guanshu; Fang, Dawei; Wang, Jun; Song, Youtao

2017-07-01

Here, we reported a novel method to dispose caffeine by means of ultrasound irradiation combinated with CdS@(Er 3+ :Y 3 Al 5 O 12 /ZrO 2 ) coated composite as sonocatalyst. The CdS@(Er 3+ :Y 3 Al 5 O 12 /ZrO 2 ) was synthesized via hydrothermal-precipitation method and then characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX) and UV-vis diffuse reflectance spectra (DRS). After that, the sonocatalytic degradation of caffeine in aqueous solution was conducted adopting CdS@(Er 3+ :Y 3 Al 5 O 12 /ZrO 2 ) and CdS@ZrO 2 coated composites as sonocatalysts. In addition, some influencing factors such as CdS and ZrO 2 molar proportion, caffeine concentration, ultrasonic irradiation time, sonocatalyst dosage and addition of several inorganic oxidants on sonocatalytic degradation of caffeine were investigated by using UV-vis spectra and gas chromatograph. The experimental results showed that the presence of Er 3+ :Y 3 Al 5 O 12 could effectively improve the sonocatalytic degradation activity of CdS@ZrO 2 . To a certain extent some inorganic oxidants can also enhance sonocatalytic degradation of caffeine in the presence of CdS@(Er 3+ :Y 3 Al 5 O 12 /ZrO 2 ). The best sonocatalytic degradation ratio (94.00%) of caffeine could be obtained when the conditions of 5.00mg/L caffeine, 1.00g/L prepared CdS@(Er 3+ :Y 3 Al 5 O 12 /ZrO 2 ), 10.00mmol/LK 2 S 2 O 8 , 180min ultrasonic irradiation (40kHz frequency and 50W output power), 100mL total volume and 25-28°C temperature were adopted. It seems that the method of sonocatalytic degradation caused by CdS@(Er 3+ :Y 3 Al 5 O 12 /ZrO 2 ) displayspotentialadvantages in disposing caffeine. Copyright © 2017 Elsevier B.V. All rights reserved.

GITT studies on oxide cathode LiNi1/3Co1/3Mn1/3O2 synthesized ...

Indian Academy of Sciences (India)

2016-08-26

Aug 26, 2016 ... GITT studies on oxide cathode LiNi1/3Co1/3Mn1/3O2 synthesized by citric acid assisted high-energy ball milling ... The State Key Laboratory Base of Novel Functional Materials and Preparation Science; The Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, P. R. ...

Indentation studies on Y2O3-stabilized ZrO2

International Nuclear Information System (INIS)

Dransmann, G.W.; Steinbrech, R.W.; Pajares, A.; Guiberteau, F.; Dominguez-Rodriguez, A.; Heuer, A.H.

1994-01-01

Stable indentation cracks were grown in four-point bend tests to study the fracture toughness of two Y 2 O 3 -stabilized ZrO 2 ceramics containing 3 and 4 mol% Y 2 O 3 . By combining microscopic in situ stable crack growth observations at discrete stresses with crack profile measurements, the dependence of toughness on crack extension was determined from crack extension plots, which graphically separate the crack driving residual stress intensity and applied stress intensity factors. Both materials exhibit steeply rising R-curves, with a plateau toughness of 4.5 and 3.1 MPa·m 1/2 for the 3- and 4-mol% materials, respectively. The magnitude of the plateau toughness reflects the fraction of tetragonal grain contributing to transformation toughening

In situ screen-printed BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} electrolyte-based protonic ceramic membrane fuel cells with layered SmBaCo{sub 2}O{sub 5+x} cathode

Energy Technology Data Exchange (ETDEWEB)

Lin, Bin; Dong, Yingchao; Zhang, Shangquan; Hu, Mingjun; Zhou, Yang; Meng, Guangyao [Department of Materials Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026 (China); Yan, Ruiqiang [Department of Materials Engineering, Taizhou University, Linhai, Zhejiang 317000 (China)

2009-01-15

In order to develop a simple and cost-effective route to fabricate protonic ceramic membrane fuel cells (PCMFCs) with layered SmBaCo{sub 2}O{sub 5+x} (SBCO) cathode, a dense BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (BZCY) electrolyte was fabricated on a porous anode by in situ screen printing. The porous NiO-BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (NiO-BZCY) anode was directly prepared from metal oxide (NiO, BaCO{sub 3}, ZrO{sub 2}, CeO{sub 2} and Y{sub 2}O{sub 3}) by a simple gel-casting process. An ink of metal oxide (BaCO{sub 3}, ZrO{sub 2}, CeO{sub 2} and Y{sub 2}O{sub 3}) powders was then employed to deposit BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (BZCY) thin layer by an in situ reaction-sintering screen printing process on NiO-BZCY anode. The bi-layer with 25 {mu}m dense BZCY electrolyte was obtained by co-sintering at 1400 C for 5 h. With layered SBCO cathode synthesized by gel-casting on the bi-layer, single cells were assembled and tested with H{sub 2} as fuel and the static air as oxidant. A high open-circuit potential of 1.01 V, a maximum power density of 382 mW cm{sup -2}, and a low polarization resistance of the electrodes of 0.15 {omega} cm{sup 2} was achieved at 700 C. (author)

Dependence of glass-forming ability on starting compositions in Y2O3–Al2O3–SiO2 system

OpenAIRE

Yixiang Chen; Zengchao Yang; Bin He; Guanghua Liu; Jiangtao Li; Liang Wu

2011-01-01

The dependence of glass-forming ability on starting compositions in Y2O3–Al2O3–SiO2 (YAS) system has been investigated by melting experiment. Transparent YAS glasses have been prepared under the condition of furnace cooling instead of quenching. It is found that, in the YAS ternary phase diagram, the compositions on the Y3Al5O12–SiO2 line and with 52-68 mol% SiO2 have a higher glass-forming ability to produce pure glass. For the compositions with too much or less SiO2 or with Y/Al = 5/3, 1/1,...

Structural/surface characterization and catalytic evaluation of rare-earth (Y, Sm and La) doped ceria composite oxides for CH{sub 3}SH catalytic decomposition

Energy Technology Data Exchange (ETDEWEB)

He, Dedong; Chen, Dingkai; Hao, Husheng; Yu, Jie; Liu, Jiangping; Lu, Jichang; Liu, Feng [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500 (China); Wan, Gengping [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500 (China); Research Center for Analysis and Measurement, Hainan University, Haikou, 570228 (China); He, Sufang [Research Center for Analysis and Measurement, Kunming University of Science and Technology, Kunming, 650093 (China); Luo, Yongming, E-mail: environcatalysis222@yahoo.com [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500 (China)

2016-12-30

Highlights: • Ce{sub 0.75}RE{sub 0.25}O{sub 2-δ} (RE = Y, Sm and La) were synthesized by citrate complexation method. • Ce{sub 0.75}Y{sub 0.25}O{sub 2-δ} exhibited the best stability for the decomposition of CH{sub 3}SH. • Cation radius played a key role in determining structure and surface characteristics. • Catalytic behavior depended on synergistic role of oxygen vacancies and basic sites. • Ce{sub 2}S{sub 3} accumulation on the surface was responsible for the deactivation of catalyst. - Abstract: A series of rare earth (Y, Sm and La) doped ceria composite oxides and pure CeO{sub 2} were synthesized and evaluated by conducting CH{sub 3}SH catalytic decomposition test. Several characterization studies, including XRD, BET, Raman, H{sub 2}-TPR, XPS, FT-IR, CO{sub 2}-TPD and CH{sub 3}SH-TPD, were undertaken to correlate structural and surface properties of the obtained ceria-based catalysts with their catalytic performance for CH{sub 3}SH decomposition. More oxygen vacancies and increased basic sites exhibited in the rare earth doped ceria catalysts. Y doped ceria sample (Ce{sub 0.75}Y{sub 0.25}O{sub 2-δ}), with a moderate increase in basic sites, contained more oxygen vacancies. More structural defects and active sites could be provided, and a relatively small amount of sulfur would accumulate, which resulted in better catalytic performance. The developed catalyst presented good catalytic behavior with stability very similar to that of typical zeolite-based catalysts reported previously. However, La doped ceria catalyst (Ce{sub 0.75}La{sub 0.25}O{sub 2-δ}) with the highest alkalinity was not the most active one. More sulfur species would be adsorbed and a large amount of cerium sulfide species (Ce{sub 2}S{sub 3}) would accumulate, which caused deactivation of the catalysts. The combined effect of increased oxygen vacancies and alkalinity led to the catalytic stability of Ce{sub 0.75}Sm{sub 0.25}O{sub 2-δ} sample was comparable to that of pure CeO

Synthesis, characterization and luminescence study of Eu3+ doped Y2Sn2O7 nano-particles

International Nuclear Information System (INIS)

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

2011-01-01

In recent years, advanced materials derived from Pyrochlore-type oxides (A 2 B 2 O 7 ), have been of extensive scientific and technological interest. Chemical substitution of A or B sites of pyrochlore oxide by rare earth ions is a widely used approach to prepare thermally stable, lanthanide ion doped luminescent materials. The present study deals with the synthesis and characterization of Eu 3+ doped Y 2 Sn 2 O 7 : nanoparticles prepared by the hydrolysis of Y 3+ , Sn 4+ , and Eu 3+ in ethylene glycol medium followed by heating at 700 deg C for 4 hours. As prepared samples are amorphous in nature and 700 deg C heated sample showed well crystalline pyrochlore structure in XRD studies. Average particle size is calculated from the width of the X-ray diffraction peaks and found to t be around 5 nm. Luminescence measurements were carried out for as prepared and 700 deg C heated samples. The undoped as prepared sample showed a broad emission peak around 420 nm after excitation at 285 nm. While for 700 deg C undoped heated sample, the peak maxima was shifted to 435 nm. The emission spectrum for doped as prepared samples is characterized by both host emission around 420 nm along with the characteristic Eu 3+ emission peaks in the visible region. However, very poor Eu 3+ emission from heated sample was observed

Catalytic properties of oxygen adsorbed on NiO-Sm/sub 2/O/sub 3/ binary oxides

Energy Technology Data Exchange (ETDEWEB)

Tadasu, Y.; Niwa, H.; Matsuda, Y.

1978-02-01

Various rare earths were screened as promoters for a nickel oxidation catalyst, and samarium (Sm) was selected for further studies. The activity of a physical mixture of NiO/Sm/sub 2/O/sub 3/ and SiC for the oxidation of 500 ppm nitric oxide with 5% oxygen in nitrogen to nitrogen dioxide at 320/sup 0/C went through a maximum with increasing Sm/sub 2/O/sub 3/ content of the catalyst. The most active catalyst, which contained 3.75% Sm/sub 2/O/sub 3/, was 3.7 times as active as pure nickel oxide. Temperature-programed desorption of oxygen from the catalysts revealed three peaks, ..cap alpha.. at 220/sup 0/-230/sup 0/C ..beta.. at 370/sup 0/-380/sup 0/C, and ..gamma.. at 530/sup 0/-540/sup 0/C, for all catalysts except pure Sm/sub 2/O/sub 3/. The amount of adsorbed oxygen increased with increasing Sm/sub 2/O/sub 3/ content to 3.75%, and then decreased with further Sm/sub 2/O/sub 3/ increases. The catalytic activity was correlated to oxygen in the ..beta..-state. Graphs, spectra, and table.

Y{sub 2}BaCuO{sub 5} particle distribution in YBa{sub 2}Cu{sub 3}O{sub 7-y} grains of melt growth processed YBCO oxides; Y{sub 2}BaCuO{sub 5}-Partikelverteilung in YBa{sub 2}Cu{sub 3}O{sub 7-y}-Koernern durch das Melt-Growth-Verfahren verarbeiteter YBCO-Oxide

Energy Technology Data Exchange (ETDEWEB)

Kim, Chan-Joong; Park, Soon-Dong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of). Neutron Science Div.; Park, Hai-Woong [Korea Univ. of Technology and Education, Chungnam (Korea, Republic of). College of Energy, Materials and Chemical Engineering

2013-02-01

Y{sub 2}BaCuO{sub 5} (Y211) particle distribution within YBa{sub 2}Cu{sub 3}O{sub 7-y} (Y123) grains of YBCO samples melt growth (MG) processed was examined. To understand the processing variables on the Y211 distribution, a cooling rate (R{sub C}=1 K/h to R{sub C}=20 K/h) through a peritectic temperature (T{sub p} = 1010 C), a precursor powder size and composition were changed. Two different Y211 distributions (a linear x-like track and planar butterfly-like pattern) were observed, depending on the processing variables. The linear x-like Y211 tracks were observed in the Y123 samples prepared using a stoichiometric Y123 precursor, whereas the planar butterfly-like Y211 patterns were observed in the Y{sub 1.8}Ba{sub 2.4}Cu{sub 3.4}O{sub 7-d} (Y1.8) samples prepared using an Y211-excess composition precursor. The track and planar Y211 patterns were clearer at lower R{sub C} (slower growth rate of Y123 grains) and for the smaller Y211 particles. In contrast, the random Y211 distribution was dominant at the higher R{sub C} and for the larger Y211 particles. The Y211 distribution patterns in the Y123 grains were explained in terms of the interfacial energy difference among growing Y123 fronts. (orig.)

Transport and thermoelectric properties of n-type Ruddlesden-Popper phase (Sr1-xGdx)3(Ti1-yTay)2O7 oxides

International Nuclear Information System (INIS)

Sun, R R; Qin, X Y; Li, L L; Li, D; Zhang, J; Wang, Q Q

2012-01-01

The transport and thermoelectric properties of (Sr 1-x Gd x ) 3 (Ti 1-y Ta y ) 2 O 7 (x = 0.05, y = 0.05-0.15; x = 0.1, y = 0.05-0.1) compounds with Ruddlesden-Popper (RP) phase, prepared by a conventional solid-state reaction method plus spark plasma sintering (SPS), were investigated in the temperature range from 300 to 1000 K. The results indicate that the electrical resistivity ρ for all compounds increases with temperature, and has a relation ρ ∝ T M (i.e. the mobility μ ∝ T -M ) with M = 1.58-1.92 at T ≳ 650 K, indicating that the phonon scattering is predominant. Basically, the absolute value of the Seebeck coefficient |S| increases almost linearly with temperature above ∼400 K, showing degenerated semiconducting behaviour. Moreover, both ρ and |S| decrease with the increase in both Ta and Gd content, which can be attributed to an increase in the carrier concentration. The lattice thermal conductivity κ L of the compounds decreases monotonically with an increase in both Ta and Gd content due to mass-defect phonon scattering, and the lowest κ L (κ L = 3.3 W K -1 m -1 at room temperature and 2.0 W K -1 m -1 at 1000 K) is achieved in (Sr 0.9 Gd 0.1 ) 3 (Ti 0.9 Ta 0.1 ) 2 O 7 . Among all the compounds investigated here, the largest dimensionless figure of merit ZT = 0.08 (at 1000 K) is obtained in the compound (Sr 0.9 Gd 0.1 ) 3 (Ti 0.95 Ta 0.05 ) 2 O 7 .

Rapid rate sintering of nanocrystalline ZrO2-3 mol% Y2O3

International Nuclear Information System (INIS)

Chen, D.J.; Mayo, M.J.

1996-01-01

Conventional ramp-and-hold sintering with a wide range of heating rates was conducted on submicrometer and nanocrystalline ZrO 2 -3 mol% Y 2 O 3 powder compacts. Although rapid heating rates have been reported to produce high density/fine grain size products for many submicrometer and smaller starting powders, the application of this technique to ZrO 2 -3 mol% Y 2 O 3 produced mixed results. In the case of submicrometer ZrO 2 -3 mol% Y 2 O 3 , neither densification nor grain growth was affected by the heating rate used. In the case of nanocrystalline ZrO 2 -3 mol% Y 2 O 3 , fast heating rates severely retarded densification and had a minimal effect on grain growth. The large adverse effect of fast heating rates on the densification of the nanocrystalline powder was traced to a thermal gradient/differential densification effect. Microstructural evidence suggests that the rate of densification greatly exceeded the rate of heat transfer in this material; consequently, the sample interior was not able to densify before being geometrically constrained by a fully dense shell which formed at the sample exterior. This finding implies that rapid rate sintering will meet severe practical constraints in the manufacture of bulk nanocrystalline ZrO 2 -3 mol% Y 2 O 3 specimens

The structural changes of Y2O3 in ferritic ODS alloys during milling

International Nuclear Information System (INIS)

Hilger, I.; Tegel, M.; Gorley, M.J.; Grant, P.S.; Weißgärber, T.; Kieback, B.

2014-01-01

Oxide dispersion strengthened (ODS) ferritic steels are usually fabricated via mechanical alloying and subsequent consolidation via hot extrusion or hot isostatic pressing. During the individual process steps, a complex evolution of the nanoparticle structure is taking place. Powders with different Y 2 O 3 contents were milled and examined by means of X-ray diffraction (XRD) and atom probe tomography (APT). It has been observed that the Y 2 O 3 is fragmented and becomes partially amorphous upon milling due to the grain refinement of Y 2 O 3 during the milling process. There was no compelling evidence for Y 2 O 3 dissociation and dissolution into the steel matrix

Interaction of Ce{sub 1−x}Er{sub x}O{sub 2−y} nanoparticles with SiO{sub 2}-effect of temperature and atmosphere

Energy Technology Data Exchange (ETDEWEB)

Kepinski, L., E-mail: L.Kepinski@int.pan.wroc.pl; Krajczyk, L.; Mista, W.

2014-01-15

Morphology, microstructure and phase evolution of homogeneous, nanocrystalline Ce{sub 1−x}Er{sub x}O{sub 2−x/2} mixed oxide (x=0.3 and 0.5), prepared by microemulsion method, supported on amorphous SiO{sub 2} was studied in oxidizing and reducing atmosphere by XRD, TEM, SEM-EDS and N{sub 2} adsorption. The system is structurally and chemically stable in the oxidizing atmosphere up to 1000 °C, exhibiting only a small increase of the mean crystallite size of the oxide to ∼4 nm. At 1100 °C formation of Er silicate with unusual structure isomorphic with y-Y{sub 2}Si{sub 2}O{sub 7} (yttrialite), stabilized by Ce{sup 4+} ions was observed. In the reducing atmosphere the Ce{sub 1−x}Er{sub x}O{sub 2−x/2} reacted with SiO{sub 2} already at 900 °C, due to high affinity of the reduced Ce{sup 3+} to form a silicate phase. At higher temperature the silicate crystallized into the tetragonal, low temperature A-(Ce{sub 1−x}Er{sub x}){sub 2}Si{sub 2}O{sub 7} polymorph. Such systems, containing nanocrystalline silicate particles with Er{sup 3+} ions placed in well defined sites embedded in silica matrix, may be interesting as highly efficient active components of optical waveguides amplifiers integrated with Si microelectronics. The nanocrystalline Ce–Er–O/SiO{sub 2} system prepared by the impregnation of the silica with the aqueous solution of nitrates appeared to be chemically inhomogeneous and less stable in both oxidising and reducing atmosphere. - Graphical abstract: Structure evolution of Ce{sub 0.5}Er{sub 0.5}O{sub 1.75} in air and in H{sub 2}. Display Omitted - Highlights: • Homogeneous 3 nm Ce{sub 1−x}Er{sub x}O{sub 2−y} particles were prepared and uniformly dispersed on SiO{sub 2}. • Er diffusion to SiO{sub 2} determines the stability of the mixed oxide in air to ∼1000 °C. • Spreading of Ce{sub 1−x}Er{sub x}O{sub 2−y} onto SiO{sub 2} occurs in hydrogen at 900 °C. • Nanocrystalline A-(Ce,Er){sub 2}Si{sub 2}O{sub 7} silicate forms in H

Crystallization and characterization of Y2O3-SiO2 glasses

Science.gov (United States)

Drummond, Charles H., III; Lee, William E.; Sanders, W. A.; Kiser, J. D.

1991-01-01

Glasses in the yttria-silica system with 20 to 40 mol pct Y2O3 were subjected to recrystallization studies after melting at 1900 to 2100 C in W crucibles in 1 and 50 atm N2. The TEM and XRD results obtained indicate the presence of the delta, gamma, gamma prime, and beta-Y2Si2O7 crystalline phases, depending on melting and quenching conditions. Heat treatment in air at 1100 to 1600 C increased the amount of crystallization, and led to the formation of Y2SiO5, cristabalite, and polymorphs of Y2Si2O7. Also investigated were the effects of 5 and 10 wt pct zirconia additions.

Recycling of the rare earth oxides from spent rechargeable batteries using waste metallurgical slags

Directory of Open Access Journals (Sweden)

Tang K.

2013-01-01

Full Text Available A high temperature process for recycling spent nickel-metal hydride rechargeable batteries has been recently developed at SINTEF/NTNU. The spent battery modules were first frozen with liquid nitrogen for the de-activation and brittle fracture treatment. The broken steel scraps and plastics were then separated by the mechanical classification and magnetic separation. The remaining positive and negative electrodes, together with the polymer separator, were heated to 600-800oC in order to remove the organic components and further separate the Ni-based negative electrode. XRF analyses indicate that the heat-treated materials consist mainly of nickel, rare earth and cobalt oxides. The valuable rare earth oxides were further recovered by the high-temperature slagging treatment. The waste metallurgical slags, consist mainly of SiO2 and CaO, were used as the rare earth oxide absorbent. After the high temperature slagging treatment, over 98% of nickel and cobalt oxides were reduced to the metal phase; meanwhile almost all rare earth oxides remain in the molten slags. Furthermore, EPMA and XRF analyses of the slag samples indicate that the rare earth oxides selectively precipitate in the forms of solid xSiO2•yCaO•zRe2O3. The matrix of slag phase is Re2O3 deficient, typically being less than 5 wt%. This provides a sound basis to further develop the high-temperature process of concentrating the Re2O3 oxides in slags.

Effects of Y{sub 2}O{sub 3}/CeO{sub 2} co-doping on microwave dielectric properties of Ba(Co{sub 0.6}Zn{sub 38}){sub 1/3}Nb{sub 2/3}O{sub 3} ceramics

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yuqin; Zhou, Xiaohua, E-mail: 1250590698@qq.com; Yang, Xinshi; Sun, Chengli; Yang, Fan; Chen, Hetuo

2016-09-15

The effects of CeO{sub 2}/Y{sub 2}O{sub 3} co-doping on the microstructure and microwave dielectric properties of Ba(Co{sub 0.6}Zn{sub 0.38}){sub 1/3}Nb{sub 2/3}O{sub 3}-xA-xB (x = 0,1,2,3,4,6; A = 0.1204 wt%Y{sub 2}O{sub 3}; B = 0.1 wt%CeO{sub 2}) ceramics prepared by the conventional solid-state route technique were investigated. The X-ray diffraction (XRD) results presented that all the well sintered samples exhibited the main phase BaZn{sub 0.33}Nb{sub 0.67}O{sub 3}−Ba{sub 3}CoNb{sub 2}O{sub 9}. A certain amount of Ba{sub 8}CoNb{sub 6}O{sub 24} surface secondary phase and minority phase of Ba{sub 5}Nb{sub 4}O{sub 15} were also observed in all sintered ceramics. The 1:2 B-site cation ordering degree was found to influenced by the substitution of Y{sup 3+} and Ce{sup 4+} in the crystal lattice, especially for x = 0.02. Then the scanning electron microscopy (SEM) picture of the optimally well-sintered (1350 °C for 20 h) ceramic has shown a dense microstructure. Although the ε{sub r} almost kept unchanged, appropriate doping content would greatly improve the Q × f value. Meanwhile, the τ{sub f} value first declined and then increased with increasing x. At last, the excellent microwave dielectric properties of ε{sub r} = 36.09, Q × f = 72006 GHz, τ{sub f} = 3.35 ppm/ºC were obtained for the ceramic with x = 0.02 sintered in air at 1350 °C for 20 h. - Graphical abstract: Fig. SEM images of as-sintered Ba(Co{sub 0.6}Zn{sub 0.38}){sub 1/3}Nb{sub 2/3}O{sub 3}-xA-Xb (A = 0.1204 wt%Y{sub 2}O{sub 3}; B = 0.1 wt%CeO{sub 2)}ceramics: (a) x = 0,(b) x = 0.01,(c) x = 0.02,(d) x = 0.03, (e) x = 0.04,(f) x = 0.06. The images confirmed the presences of two phases on the surface of the ceramics, plate-shaped grains (Ba{sub 8}(C{sub O},Zn){sub 1}Nb{sub 6}O{sub 24}phase) and needle-shaped grains (Ba{sub 3}(Co{sub 0.6}Zn{sub 0.38}){sub 1}Nb{sub 2}O{sub 9} phase). As a small content of CeO{sub 2}/Y{sub 2}O{sub 3} (x = 0.01–0.04) was codoped into the BCZN ceramics, the

Remarkable changes in the photoluminescent properties of Y2Ce2O7:Eu(3+) red phosphors through modification of the cerium oxidation states and oxygen vacancy ordering.

Science.gov (United States)

Raj, Athira K V; Prabhakar Rao, P; Sreena, T S; Sameera, S; James, Vineetha; Renju, U A

2014-11-21

A new series of red phosphors based on Eu(3+)-doped yttrium cerate [Y1.9Ce2O7:0.1Eu(3+), Y2Ce1.9O7:0.1Eu(3+) and Y2Ce2-xO7:xEu(3+) (x = 0.05, 0.10, 0.15, 0.20, 0.25 and 0.50)] was prepared via a conventional solid-state method. The influence of the substitution of Eu(3+) at the aliovalent site on the photoluminescent properties was determined by powder X-ray diffraction, FT Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy with energy-dispersive spectroscopy, UV-visible absorption spectroscopy, photoluminescence spectroscopy and lifetime measurements. The substitution of Eu(3+) at the Ce(4+) site induces a structural transition from a defect fluorite to a C-type structure, which increases the oxygen vacancy ordering and the distortion of the Eu(3+) environment, and decreases the formation of Ce(3+) states. In contrast, phosphors with isovalent substitution at the Y(3+) site exhibit the biphasic nature of defect fluorite and a C-type structure, thereby increasing the number of Ce(3+) oxidation states. These modifications resulted in remarkable changes in the photoluminescent properties of Y2Ce1.9O7:0.1Eu(3+) red phosphors, with emission intensities 3.8 times greater than those of the Ce0.9O2:0.1Eu(3+) and Y1.9Ce2O7:0.1Eu(3+). The photoluminescent properties of Y2Ce2-xO7:xEu(3+) were studied at different Eu(3+) concentrations under excitation with blue light. These phosphors emit intense red light due to the (5)D0-(7)F2 transition under excitation at 466 nm and no concentration quenching is observed with up to 50 mol% Eu(3+). They show increased lifetimes in the range 0.62-0.72 ms at Eu(3+) concentrations. The cation ordering linked to the oxygen vacancy ordering led to the uniform distribution of Eu(3+) ions in the lattice, thus allowing higher doping concentrations without quenching and consequently increasing the lifetime of the (5)D0 states. Our results demonstrate that significant improvements in

Intergranular phase of the Si3 N4 hot pressed with Mg O/Y2 O3

International Nuclear Information System (INIS)

Costa, Celio A.; Todd, Judith A.

1997-01-01

Monolithic and composite Si 3 N 4 hot-pressed with 3% Mgo or 6% Y 2 O 3 were analyzed with X-ray diffraction and transmission electron microscopy. The results showed materials to be composed of β-Si 3 N 4 grains and an intergranular phase which was partially crystalline and partially amorphous. For the materials sintered with Mg O, the identification of the intergranular phase was not conclusive. For the materials sintered with Y 2 O 3 . It was observed that the amount of intergranular crystalline phase decreased as whiskers were added to the material and the intergranular crystalline part had a crystallographic structure similar to yttrium-silicon-oxide-nitride family. (author)

Amperometric L-cysteine sensor based on a carbon paste electrode modified with Y_2O_3 nanoparticles supported on nitrogen-doped reduced graphene oxide

International Nuclear Information System (INIS)

Yang, Suling; Li, Gang; Wang, Yuanyuan; Wang, Guifang; Qu, Lingbo

2016-01-01

We describe an electrochemical sensor for L-cysteine that is based on the use of Y_2O_3 nanoparticles (Y_2O_3-NPs) supported on nitrogen-doped reduced graphene oxide (N-rGO). The material was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and electrochemical methods. Deposited on a carbon paste electrode, the material displays a strongly oxidation peak for L-cysteine at pH 7.0 (compared to an unmodified electrode). The current, measured at a potential 0.7 V (vs. Ag/AgCl), increases linearly in the 1.3 to 720 μM L-cysteine concentration range, and the detection limit is 0.8 μM. The sensor was successfully applied to the determination L-cysteine in spiked syrup. (author)

[Mechanism and performance of styrene oxidation by O3/H2O2].

Science.gov (United States)

He, Jue-Cong; Huang, Qian-Ru; Ye, Qi-Hong; Luo, Yu-Wei; Zhang, Zai-Li; Fan, Qing-Juan; Wei, Zai-Shan

2013-10-01

It can produce a large number of free radicals in O3/H2O2, system, ozone and free radical coupling oxidation can improve the styrene removal efficiency. Styrene oxidation by O3/H2O2 was investigated. Ozone dosage, residence time, H2o2 volume fraction, spray density and molar ratio of O3/C8H8 on styrene removal were evaluated. The experimental results showed that styrene removal efficiency achieved 85.7%. The optimal residence time, H2O2, volume fraction, spray density and O3/C8H8 molar ratio were 20. 6 s, 10% , 1.72 m3.(m2.h)-1 and 0.46, respectively. The gas-phase degradation intermediate products were benzaldehyde(C6H5CHO) and benzoic acid (C6H5 COOH) , which were identified by means of gas chromatography-mass spectrometry(GC-MS). The degradation mechanism of styrene is presented.

Potential rare-earth modified CeO{sub 2} catalysts for soot oxidation. Part III. Effect of dopant loading and calcination temperature on catalytic activity with O{sub 2} and NO + O{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Krishna, K.; Bueno-Lopez, A.; Makkee, M.; Moulijn, J.A. [Catalysis Engineering, DelftChemTech, Delft University of Technology, Julianalaan 136, NL 2628 BL Delft (Netherlands)

2007-09-26

CeO{sub 2} and CeReO{sub xy} catalysts are prepared by the calcination at different temperatures (y = 500-1000 C) and having a different composition (Re = La{sup 3+} or Pr{sup 3+/4+}{sub ,} 0-90 wt.%). The catalysts are characterised by XRD, H{sub 2}-TPR, Raman, and BET surface area. The soot oxidation is studied with O{sub 2} and NO + O{sub 2} in the tight and loose contact conditions, respectively. CeO{sub 2} sinters between 800-900 C due to a grain growth, leading to an increased crystallite size and a decreased BET surface area. La{sup 3+} or Pr{sup 3+/4+} hinders the grain growth of CeO{sub 2} and, thereby, improving the surface catalytic properties. Using O{sub 2} as an oxidant, an improved soot oxidation is observed over CeLaO{sub xy} and CePrO{sub xy} in the whole dopant weight loading and calcination temperature range studied, compared with CeO{sub 2}. Using NO + O{sub 2}, the soot conversion decreased over CeLaO{sub xy} catalysts calcined below 800 C compared with the soot oxidation over CeO{sub 2y}. CePrO{sub xy}, on the other hand, showed a superior soot oxidation activity in the whole composition and calcination temperature range using NO + O{sub 2}. The improvement in the soot oxidation activity over the various catalysts with O{sub 2} can be explained based on an improvement in the external surface area. The superior soot oxidation activity of CePrO{sub xy} with NO + O{sub 2} is explained by the changes in the redox properties of the catalyst as well as surface area. CePrO{sub xy}, having 50 wt.% of dopant, is found to be the best catalyst due to synergism between cerium and praseodymium compared to pure components. NO into NO{sub 2} oxidation activity, that determines soot oxidation activity, is improved over all CePrO{sub x} catalysts. (author)

Single-Crystal Y2O3 Epitaxially on GaAs(001 and (111 Using Atomic Layer Deposition

Directory of Open Access Journals (Sweden)

Y. H. Lin

2015-10-01

Full Text Available Single-crystal atomic-layer-deposited (ALD Y\\(_{\\mathrm{2}}\\O\\(_{\\mathrm{3}}\\ films 2 nm thick were epitaxially grown on molecular beam epitaxy (MBE GaAs(001-4 \\(\\times\\ 6 and GaAs(111A-2 \\(\\times\\ 2 reconstructed surfaces. The in-plane epitaxy between the ALD-oxide films and GaAs was observed using \\textit{in-situ} reflection high-energy electron diffraction in our uniquely designed MBE/ALD multi-chamber system. More detailed studies on the crystallography of the hetero-structures were carried out using high-resolution synchrotron radiation X-ray diffraction. When deposited on GaAs(001, the Y\\(_{\\mathrm{2}}\\O\\(_{\\mathrm{3}}\\ films are of a cubic phase and have (110 as the film normal, with the orientation relationship being determined: Y\\(_{\\mathrm{2}}\\O\\(_{\\mathrm{3}}\\(\\(110\\[\\(001\\][\\(\\overline{1}10\\]//GaAs(\\(001\\[\\(110\\][\\(1\\overline{1}0\\]. On GaAs(\\(111\\A, the Y\\(_{\\mathrm{2}}\\O\\(_{\\mathrm{3}}\\ films are also of a cubic phase with (\\(111\\ as the film normal, having the orientation relationship of Y\\(_{\\mathrm{2}}\\O\\(_{\\mathrm{3}}\\(\\(111\\[\\(2\\overline{1}\\overline{1}\\] [\\(01\\overline{1}\\]//GaAs (\\(111\\ [\\(\\overline{2}11\\][\\(0\\overline{1}1\\]. The relevant orientation for the present/future integrated circuit platform is (\\(001\\. The ALD-Y\\(_{\\mathrm{2}}\\O\\(_{\\mathrm{3}}\\/GaAs(\\(001\\-4 \\(\\times\\ 6 has shown excellent electrical properties. These include small frequency dispersion in the capacitance-voltage CV curves at accumulation of ~7% and ~14% for the respective p- and n-type samples with the measured frequencies of 1 MHz to 100 Hz. The interfacial trap density (Dit is low of ~10\\(^{12}\\ cm\\(^{−2}\\eV\\(^{−1}\\ as extracted from measured quasi-static CVs. The frequency dispersion at accumulation and the D\\(_{it}\\ are the lowest ever achieved among all the ALD-oxides on GaAs(\\(001\\.

Emission characteristics of Y1Ba2Cu3O7-δ cathode

International Nuclear Information System (INIS)

Korenev, S.A.

1988-01-01

The results are presented of experimental investigation of the electron beam in diode with cathode on the base of Y 1 Ba 2 Cu 3 O 7-δ . After corresponding cathode training, the cathode made from Y 1 Ba 2 Cu 3 O 7-δ material may be practicable of stable current electron beam yeild. It is shown experimentally that the voltage of diode of about 100-300 kV there exists an evident possibility of forming the electron beams with the current density of 70 A-380 A/cm 2 . The motion velicity of cathode plasma in the direction of anode for this material of a cathode amounts to (1-3)x 10 6 cm/s

Microestructura de Al2O3/TZP codopado con Fe2O3 y TiO2 fabricado por reacción (RBAO

Directory of Open Access Journals (Sweden)

Jiménez, M.

2003-02-01

Full Text Available Reaction-bonded 80 vol% Al2O3/TZP (2 mol% Y2O3-stabilized tetragonal zirconia polycrystals composites co-doped with 1 vol% Fe2O3 and 1 vol% TiO2 have been produced, and then presureless sintered (1450 ºC, 60 min or sinter-forged (20 MPa, 1200 ºC, 60 min. The resulting microstructures have been characterized using scanning electron microscopy. Both types of materials are dense, with a fine and homogeneous dual microstructure consisting of Al2O3 and TZP grains without intermediate grain boundary phases. Sinter-forged composites exhibit a very narrow pore size distribution, essentially smaller than the grain size of the alumina and zirconia phases. Co-doping promotes the sintering of alumina at lower temperatures, while still retains a fine grain size due to the presence of the dispersed zirconia phase. First results on presureless sintered RBAO materials show a fracture strength higher than in conventionally sintered and sinter-forged composites.Se han fabricado compuestos de 80% vol. Al2O3/TZP (ZrO2 estabilizada con 2% mol Y2O3 codopados con 1% vol. Fe2O3 y 1% vol. TiO2 mediante la tecnología RBAO (“Reaction Bonding of Aluminum Oxide”, que se han sinterizado libremente (1450 ºC, 60 min y bajo carga uniaxial (20 MPa, 1200 ºC, 60 min. Se ha caracterizado la microestructura mediante microscopía electrónica de barrido. Ambos materiales son densos con una microestructura homogénea formada por granos de alúmina y de circona, sin fases en juntas de grano. En el caso de la sinterización bajo carga, la distribución del tamaño de los poros es muy estrecha, y esencialmente menor que las correspondientes a los granos de Al2O3 y TZP. El codopado promueve la sinterización de la alúmina, mientras que los granos dispersos de circona inhiben su crecimiento de grano. Los ensayos preliminares de flexión en cuatro puntos realizados sobre los materiales sinterizados sin carga indican una resistencia a la fractura superior a la que presentan los

Analysis of the conductivity of commercial easy sintering grade 3 mol% Y{sub 2}O{sub 3}-ZrO{sub 2} materials

Energy Technology Data Exchange (ETDEWEB)

Badwal, Sukhvinder P.S.; Ciacchi, Fabio T.; Giampietro, Kristine M. [CSIRO, Manufacturing and Infrastructure Technology, Private Bag 33, Clayton South 3169, Victoria (Australia)

2005-01-14

Fine grain zirconia-yttria materials are required for enhanced performance in solid oxide fuel cells and related devices and in applications requiring good thermo-mechanical properties. Materials with about 3 mol% Y{sub 2}O{sub 3}-ZrO{sub 2} composition are good electrolyte materials for solid oxide fuel cell, ceramic membrane oxygen separation and a number of related devices because of their superior mechanical properties and ease of fabrication into thin self-supporting structures in comparison with a material in the 8-10 mol% Y{sub 2}O{sub 3}-ZrO{sub 2} composition range. In this study, sintering behaviour, impedance studies, four-probe DC conductivity measurements and microstructure analysis has been performed on various easy sintering grade materials from two commercial powder suppliers. These materials achieve near theoretical density at sintering temperatures as low as 1350-1400C. For direct comparison of the conductivity and impedance behaviour in easy sintering grade materials, several other 3 mol% Y{sub 2}O{sub 3}-ZrO{sub 2} powders were also investigated. The total ionic conductivity at 850C in easy sintering grade materials is comparable with normal-grade commercial materials of similar composition despite a slightly higher grain boundary impedance at lower temperatures (below circa 450C). There were no obvious differences in the grain boundary thickness, calculated from the impedance data, of normal and easy sintering grade materials.

Impact of ultra-thin Al2O3-y layers on TiO2-x ReRAM switching characteristics

Science.gov (United States)

Trapatseli, Maria; Cortese, Simone; Serb, Alexander; Khiat, Ali; Prodromakis, Themistoklis

2017-05-01

Transition metal-oxide resistive random access memory devices have demonstrated excellent performance in switching speed, versatility of switching and low-power operation. However, this technology still faces challenges like poor cycling endurance, degradation due to high electroforming (EF) switching voltages and low yields. Approaches such as engineering of the active layer by doping or addition of thin oxide buffer layers have been often adopted to tackle these problems. Here, we have followed a strategy that combines the two; we have used ultra-thin Al2O3-y buffer layers incorporated between TiO2-x thin films taking into account both 3+/4+ oxidation states of Al/Ti cations. Our devices were tested by DC and pulsed voltage sweeping and in both cases demonstrated improved switching voltages. We believe that the Al2O3-y layers act as reservoirs of oxygen vacancies which are injected during EF, facilitate a filamentary switching mechanism and provide enhanced filament stability, as shown by the cycling endurance measurements.

Eu3+-doped (Y0.5La0.5)2O3: new nanophosphor with the bixbyite cubic structure

Science.gov (United States)

Đorđević, Vesna; Nikolić, Marko G.; Bartova, Barbora; Krsmanović, Radenka M.; Antić, Željka; Dramićanin, Miroslav D.

2013-01-01

New red sesquioxide phosphor, Eu3+-doped (Y0.5La0.5)2O3, was synthesized in the form of nanocrystalline powder with excellent structural ordering in cubic bixbyite-type, and with nanoparticle sizes ranging between 10 and 20 nm. Photoluminescence measurements show strong, Eu3+ characteristic, red emission ( x = 0.66 and y = 0.34 CIE color coordinates) with an average 5D0 emission lifetime of about 1.3 ms. Maximum splitting of the 7F1 manifold of the Eu3+ ion emission behaves in a way directly proportional to the crystal field strength parameter, and experimental results show perfect agreement with theoretical values for pure cubic sesquioxides. This could be used as an indicator of complete dissolution of Y2O3 and La2O3, showing that (Y0.5La0.5)2O3:Eu3+ behaves as a new bixbyite structure oxide, M2O3, where M acts as an ion having average ionic radius of constituting Y3+ and La3+. Emission properties of this new phosphor were documented with detailed assignments of Eu3+ energy levels at 10 K and at room temperature. Second order crystal field parameters were found to be B 20 = -66 cm-1 and B 22 = -665 cm-1 at 10 K and B 20 = -78 cm-1 and B 22 = -602 cm-1 at room temperature, while for the crystal field strength the value of 1495 cm-1 was calculated at 10 K and 1355 cm-1 at room temperature.

Formation of YxNd1-xBa2Cu3O7-δ (0≤x≤0.9) superconductors from an undercooled melt via aero-acoustic levitation

International Nuclear Information System (INIS)

Gustafson, D.E.; Hofmeister, W.H.; Bayuzick, R.J.; Nagashio, K.; Kuribayashi, K.

2003-01-01

This paper presents the results of rapid solidification experiments performed on the copper oxide superconductors Y x Nd 1-x Ba 2 Cu 3 O 7-δ (0≤x≤0.9). Spherical rare earth (RE) 123 specimens were levitated in O 2 using aero-acoustic levitation (AAL), melted with a laser, undercooled, and solidified. The peritectic transformation temperature for the reaction RE 2 BaCuO 5 +liquid→REBa 2 Cu 3 O 7-δ corresponding to the maximum recalescence temperature during solidification was determined. RE123 was formed directly from the melt for Y-Nd binary alloy compositions with Nd concentration greater than 20% (Y concentration less than 80%). A minimum in the peritectic transformation temperature for the Nd/Y123 system corresponding to a composition Y 0.3 Nd 0.7 123 was determined at 66 deg. C below the peritectic of pure Nd123

The influence of excess K2O on the electrical properties of (K,Na)1/2Bi1/2TiO3 ceramics

Science.gov (United States)

Li, Linhao; Li, Ming; Sinclair, Derek C.

2018-04-01

The solid solution (KxNa0.50-x)Bi0.50TiO3 (KNBT) between Na1/2Bi1/2TiO3 and K1/2Bi1/2TiO3 (KBT) has been extensively researched as a candidate lead-free piezoelectric material because of its relatively high Curie temperature and good piezoelectric properties, especially near the morphotropic phase boundary (MPB) at x ˜ 0.10 (20 mol. % KBT). Here, we show that low levels of excess K2O in the starting compositions, i.e., (Ky+0.03Na0.50-y)Bi0.50TiO3.015 (y-series), can significantly change the conduction mechanism and electrical properties compared to a nominally stoichiometric KNBT series (KxNa0.50-x)Bi0.50TiO3 (x-series). Impedance spectroscopy measurements reveal significantly higher bulk conductivity (σb) values for y ≥ 0.10 samples [activation energy (Ea) ≤ 0.95 eV] compared to the corresponding x-series samples which possess bandgap type electronic conduction (Ea ˜ 1.26-1.85 eV). The largest difference in electrical properties occurs close to the MPB composition (20 mol. % KBT) where y = 0.10 ceramics possess σb (at 300 °C) that is 4 orders of magnitude higher than that of x = 0.10 and the oxide-ion transport number in the former is ˜0.70-0.75 compared to processing. This demonstrates the electrical properties of KNBT to be sensitive to low levels of A-site nonstoichiometry and indicates that excess K2O in KNBT starting compositions to compensate for volatilisation can lead to undesirable high dielectric loss and leakage currents at elevated temperatures.

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

Science.gov (United States)

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

2008-11-01

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

Activity of RE/sub 2/O/sub 3/ in liquid La/sub 2/O/sub 3/-Al/sub 2/O/sub 3/-CaF/sub 2/ and Ce/sub 2/O/sub 3/-CaO-CaF/sub 2/ slags

International Nuclear Information System (INIS)

Changzhen, W.; Shuqing, Y.; Qieng, D.

1985-01-01

In the course of electro-slag refining, if the slag contains rare earth oxides, the amount of rare earth introduced to the steel depends on the composition of the slag and other conditions. The main aim of this investigation is to study the activity of RE/sub 2/O/sub 3/ in the electro-slags of various compositions. One is the La/sub 2/O/sub 3/-CaO-CaF/sub 2/ ternary slag system and the other is the Ce/sub 2/O/sub 3/-CaO-CaF/sub 2/ slag system. The iso-activity diagram for RE/sub 2/O/sub 3/ and the liquid boundary for slags system were estimated

Studies on effect of europium concentration on the photoemission of laser ablated Y2O3:Eu based nano-phosphors

International Nuclear Information System (INIS)

Nissamudeen, K.M.; Krishnan, Renju R.; Rajan, Geo; Gopchandran, K.G.

2007-01-01

Full text: Phosphors are essential materials in display applications. Oxide-based phosphors are likely to emerge as the potential choice for the FED red phosphor. Among those oxide-based phosphors, there has been significant research interest in the development of Y 2 O 3 :Eu thin films as one of the most promising oxide based red phosphor systems. Yttrium oxide mixed with europium exhibit strong UV and cathode-ray-excited luminescence that are useful in lamp and display applications. Dielectric Y 2 O 3 film has recently attracted much attention for its potential application as an electric insulation layer in electroluminescent devices and high-density dynamic random access memory gate dielectrics because of its high band gap (5.8 eV) and large dielectric constant (14 to 18). Another important application of Y 2 O 3 has been in luminescent displays as a host material for rare-earth ions, specifically europium, in order to get emission of red light. In the present study thin films were deposited under a vacuum of 10 -6 mbar on fused amorphous quartz substrates using a Q-switched Nd: YAG laser, 532 nm, pulse width 9 n sec, and repetition frequency of 10 Hz, with sintered Y 2 O 3 pellets having different europium concentration as target material. Attempts were made to understand the effect of europium concentration and annealing process on the photoemission properties of the films. A europium concentration of 8 wt% and an annealing temperature of 1173 K were found to be optimum conditions for maximum photoemission. The dependence of structure and morphology of the films on the photoemission intensity are described with XRD patterns and images obtained from AFM and SEM studies

Satellite line mapping in Eu3+–Ce3+ and Pr3+–Ce3+ codoped Y2SiO5

International Nuclear Information System (INIS)

Serrano, D.; Karlsson, J.; Zheng, L.; Dong, Y.; Ferrier, A.; Goldner, P.; Walther, A.; Rippe, L.; Kröll, S.

2016-01-01

In this work we perform a high-resolution spectroscopic investigation of Eu 3+ –Ce 3+ and Pr 3+ –Ce 3+ codoped Y 2 SiO 5 crystals. Satellite line spectra were recorded at low temperatures around the Eu 3+ : 7 F 0 → 5 D 0 and the Pr 3+ : 3 H 4 → 1 D 2 transitions. It is observed that the incorporation of Ce 3+ as a codopant notably changes the Eu 3+ and Pr 3+ satellite line patterns. Satellite lines measured in singly doped Eu 3+ :Y 2 SiO 5 were found at the same spectral positions in Eu 3+ –Ce 3+ codoped crystals. These coincident lines were concluded to be due to pairs of Eu 3+ ions. Extra satellite lines appeared in the codoped crystals, which were assigned to Ce 3+ related structures such as Ce 3+ –Eu 3+ pairs. The analysis of the Pr 3+ satellite line spectra presents further challenges. Satellite lines associated to Pr 3+ pairs show weaker intensity, presumably due to the efficient quenching of the Pr 3+1 D 2 emission through cross-relaxation paths ( 1 D 2 → 1 G 4 ; 3 H 4 → 3 F 4 ). The investigation of the Eu 3+ and Pr 3+ satellite line patterns in Y 2 SiO 5 is particularly interesting for their exploitation in rare-earth based quantum computation schemes. - Highlights: • We recorded Eu and Pr satellite lines in Y 2 SiO 5 with and without Ce as a codopant. • The presence of Ce leads to the appearance of extra satellite lines in the spectra. • The satellite lines are associated to minor crystal sites such as ion pairs. • Less than 100 ion pairs were detected per satellite line. • The exploitation of the satellite line structure is proposed for quantum computing.

Local and Nanoscale Structure and Speciation in the PuO2+x-y(OH)2y ·zH2O System

International Nuclear Information System (INIS)

Conradson, Steven D.; Begg, Bruce D.; Clark, David L.; Den Auwer, Christophe J.; Ding, Mei; Dorhout, Peter K.; Espinosa-Faller, Francisco J.; Gordon, Pamela L.; Haire, Richard G.; Hess, Nancy J.; Hess, Ryan F.; Keogh, D. Webster; Morales, Luis A.; Neu, Mary P.; Paviet-Hartmann, Patricia; Runde, Wolfgang; Tait, C DREW; Veirs, D. Kirk; Villella, Phillip M.

2004-01-01

Pu L3 X-ray absorption fine structure spectra from 24 samples of PuO 2+x (and two related Pu substituted oxides), prepared by a variety of methods, demonstrate that (1) although the Pu sublattice remains the ordered part of the Pu distribution, the nearest-neighbor O atoms even at x = 0 are found in a multisite distribution with Pu-O distances consistent with the stable incorporation of OH - (and possibly H 2 O and H + ) into the PuO 2 lattice; (2) the excess O from oxidation is found at Pu-O distances 2 + moieties that are aperiodically distributed through the lattice; and (4) the collective interactions between these defect sites most likely cause them to cluster so as give nanoscale heterogeneity in the form of domains that may have unusual reactivity, observed as sequential oxidation by H 2 O at ambient conditions. The most accurate description of PuO 2 is therefore actually PuO 2+x-y (OH) 2y · zH 2 O, with pure, ordered, homogeneous PuO 2 attained only when H 2 O is rigorously excluded and the O activity is relatively low

Phase relations in the ZrO2-Nd2O3-Y2O3 system. Experimental study and CALPHAD assessment

International Nuclear Information System (INIS)

Fabrichnaya, Olga; Savinykh, Galina; Schreiber, Gerhard; Seifert, Hans J.

2010-01-01

The thermodynamic parameters of the Nd 2 O 3 Y 2 O 3 system were re-assessed for better reproduction of experimental data. The thermodynamic parameters were combined from binary descriptions to calculate phase diagrams for the ternary system ZrO 2 -Nd 2 O 3 Y 2 O 3 . The calculated phase diagrams were used to select compositions for the experimental studies at 1250, 1400 and 1600 C. The samples were synthesised by co-precipitation and heat treated at 1250-1600 C, investigated by X-ray diffraction and scanning electron microscopy combined with energy dispersive X-ray spectroscopy. It was found that solubility of the Y 2 O 3 in the pyrochlore phase exceeds 10 mol.%. The experimental data obtained for phase equilibria were used to derive thermodynamic parameters for fluorite, Y 2 O 3 cubic phase C, monoclinic B and Nd 2 O 3 hexagonal A phases by CALPHAD method. The isothermal sections and liquidus surface were calculated for the ZrO 2 -Nd 2 O 3 Y 2 O 3 system. (orig.)

Atomistic simulations of displacement cascades in Y2O3 single crystal

International Nuclear Information System (INIS)

Dholakia, Manan; Chandra, Sharat; Valsakumar, M.C.; Mathi Jaya, S.

2014-01-01

Graphical abstract: (a) The averaged distortion index and the Y–O bond length of the Y 2 O 3 octahedra as a function of the simulation time for 5 keV PKA. (b) Shows the nearest neighbourhood of one of the Y ions as a function of simulation time, showing the destruction and the recovery of the YO 6 octahedron during the cascade corresponding to 5 keV Y PKA. - Highlights: • Qualitative difference in displacement cascades exists for Y and O PKA. • Nearest neighbour correlation between Y and O ions exists even at cascade peak. • Cascade core in Y 2 O 3 does not undergo melting. • Topological connectivity of YO 6 polyhedra plays important role in stability of Y 2 O 3 . - Abstract: We study the characteristics of displacement cascades in single crystal Y 2 O 3 using classical molecular dynamics. There are two possible ways to generate the cascades in yttria, using either the Y or the O atoms as the primary knock-on (PKA) atom. It is shown that there is a qualitative difference in the characteristics of the cascades obtained in these two cases. Even though the crystal is seen to be in a highly disordered state in the cascade volume, as seen from the plots of radial distribution function, the correlation between the Y and O atoms is not completely lost. This facilitates a quick recovery of the system during the annealing phase. Topological connectivity of the YO 6 polyhedral units plays an important role in imparting stability to the Y 2 O 3 crystal. These characteristics of the cascades can help explain the stability of the yttria nanoparticles when they are dispersed in oxide dispersion strengthened steels

Synthesis of Y2O3-ZrO2-SiO2 composite coatings on carbon fiber reinforced resin matrix composite by an electro-plasma process

Science.gov (United States)

Zhang, Yuping; Lin, Xiang; Chen, Weiwei; Cheng, Huanwu; Wang, Lu

2016-05-01

In the present paper the Y2O3-ZrO2-SiO2 composite coating was successfully synthesized on carbon fiber reinforced resin matrix composite by an electro-plasma process. The deposition process, microstructures and oxidation resistance of the coatings with different SiO2 concentrations were systematically investigated. A relatively dense microstructure was observed for the Y2O3-ZrO2-SiO2 composite coating with the SiO2 concentration above 5 g/L. The coating exhibited very good oxidation resistance at 1273 K with the mass loss rate as low as ∼30 wt.%, compared to 100 wt.% of the substrate. The formation of the ceramic composites was discussed in detail based on the electrochemical mechanism and the deposition dynamics in order to explain the effect of the plasma discharge. We believe that the electro-plasma process will find wide applications in preparing ceramics and coatings in industries.

Stress relaxation of La1/2Sr1/2MnO3 and La2/3Ca1/3MnO3 at solid oxide fuel cell interfaces

International Nuclear Information System (INIS)

Lussier, A.; Dvorak, J.; Stadler, S.; Holroyd, J.; Liberati, M.; Arenholz, E.; Ogale, S.B.; Wu, T.; Venkatesan, T.; Idzerda, Y.U.

2008-01-01

Interfacial stress is thought to have significant effects on electrical and oxygen transport properties in thin films of importance in solid oxide fuel cell applications. We investigate how in-plane biaxial stress modifies the electronic structure of La 2/3 Ca 1/3 MnO 3 and La 1/2 Sr 1/2 MnO 3 thin films prepared by pulsed laser deposition on three different substrates to vary the in-plane stress from tensile to compressive. The electronic structure was probed by X-ray absorption spectroscopy of the Mn L 2,3 -edge to characterize the interfacial disruption in this region in an element-specific, site-specific manner. The compressive or tensile interfacial strain modifies the relative concentrations of La and Sr in the interfacial region in order to achieve a better lattice match to the contact material. This atomic migration generates an interfacial region dominated by a compound with a single valency for the transition metal ion, resulting in a severe barrier to oxygen and electron transport through this region

Intermediate-to-low temperature protonic ceramic membrane fuel cells with Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}}-BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} composite cathode

Energy Technology Data Exchange (ETDEWEB)

Lin, Bin; Ding, Hanping; Dong, Yingchao; Wang, Songlin; Zhang, Xiaozhen; Fang, Daru; Meng, Guangyao [Department of Materials Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026 (China)

2009-01-01

The perovskite-type Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}}-BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (BSCF-BZCY) composite oxides were synthesized by a modified Pechini method and examined as a novel composite cathode for intermediate-to-low temperature protonic ceramic membrane fuel cells (ILT-PCMFCs). Thin proton-conducting BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (BZCY) electrolyte and NiO-BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (NiO-BZCY) anode functional layer were prepared over porous anode substrates composed of NiO-BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} by a one-step dry-pressing/co-firing process. A laboratory-sized quad-layer cell of NiO-BZCY/NiO-BZCY({proportional_to}50 {mu}m)/BZCY({proportional_to}20 {mu}m)/BSCF-BZCY({proportional_to}50 {mu}m) was operated from 550 to 700 C with humidified hydrogen ({proportional_to}3% H{sub 2}O) as fuel and the static air as oxidant. A high open-circuit potential of 1.009 V, a maximum power density of 418 mW cm{sup -2}, and a low polarization resistance of the electrodes of 0.10 {omega} cm{sup 2} was achieved at 700 C. These investigations have indicated that proton-conducting BZCY electrolyte with BSCF perovskite cathode is a promising material system for the next generation solid oxide fuel cells (SOFCs). (author)

Effects of Y2O3 on crystallization kinetics of SiO2-Al2O3-CaO-CaF2 oxy-fluoride glass-ceramic system

Directory of Open Access Journals (Sweden)

M. Soleymani Zarabad

Full Text Available Differential thermal analysis (DTA patterns of SiO2-Al2O3-CaO-CaF2 oxy-fluoride glass system with adding different amounts of Y2O3 from 0.5 (wt% to 1.5 (wt% have been studied under isochronal circumstances. It is concluded that, the crystallization of the glasses is a process controlled by Avrami nucleation, three dimensional diffusion controlled growth and anisotropic growth impingement mode. Afterwards, the effective activation energy Qp, growth exponent, nucleation activation energy QN, and growth activation energy QG, have been determined and were in the range of 283–321 kJ mol−1, 2.05–2.25, 190–249 kJ mol−1 and 325–349 kJ mol−1, respectively. Qp, QN, QG and np are increased with increase of Y2O3 amount, which is related to the network forming role of Y2O3 in these systems. Keywords: Oxy-fluoride glass-ceramics, Activation energy, Crystallization mechanism, Growth exponent

The oxidation behaviour of sprayed MCrAlY coatings

International Nuclear Information System (INIS)

Brandl, W.; Toma, D.; Krueger, J.

1996-01-01

Turbine blades are protected against high temperature oxidation by thermal barrier coating (TBC) systems, which consist of a ceramic top coating (ZrO 2 /Y 2 O 3 ) and a metal bond coating (MCrAlY, M = Ni, Co). At high temperatures and under oxidative conditions, between the MCrAlY and the ceramic top coating an oxide scale is formed, which protects the metal against further oxidation. The oxidation behaviour of the thermally sprayed MCrAlY is influenced by the coating process and the composition of the metal alloys. This work is concerned with the isothermal oxidation behaviour of vacuum plasma sprayed (VPS) MCrAlY coatings. The MCrAlY powders used have different aluminium contents: 8 and 12 wt.%. The MCrAlY specimens are oxidized at 1050 C in air as well as in helium with 1% O 2 and the oxidation kinetics are determined thermogravimetrically. The microstructure, morphology and thickness of the oxide scales formed are characterized by metallography, SEM, TEM and XRD. After short time oxidation (6 h) θ-Al 2 O 3 is the main constituent of the oxide scale. Exposure times of 500 h and more lead to oxide scales consisting of α-Al 2 O 3 . Moreover, after a long time oxidation, Cr 2 O 3 and CoO (CoO on the coatings with 8 wt.% Al) are formed. The oxidation rates of both MCrAlY coatings are the same. Beneath the oxide scale an Al-depleted zone is formed and this zone is considerably thicker within the coating with 8 wt.% Al, because the amount of β-NiAl phase in this coating is lower than that in the coating with 12 wt.% Al. The oxide scale formed in He-1% O 2 consists of α-Al 2 O 3 and Cr 2 O 3 on both MCrAlY coatings. (orig.)

Influence of rare earth oxides in the oxidation of chromia forming alloys

International Nuclear Information System (INIS)

Ramanathan, L.V.

1989-01-01

The influence of superficial application of rare earth oxides such as CeO sub(2), La sub(2)O sub(3), Nd sub(2)O sub(3), Sm sub(2)O sub(3), and Gd sub(2)O sub (3) to AISI 304 and 310 stainless steels, on their isothermal oxidation behavior at 900 sup(0) and 1000 sup(0)C, and cyclic oxidation behavior between 20 sup(0) and 1000 sup(0)C has been studied. The application of rare earth oxides (REO) has been found to increase the oxidation resistance at AISI 304. No significant improvements in oxidation resistance of AISI 310 were noted. The oxidation resistance of AISI 304 was highest in the presence of CeO sub(2) on its surface. The other REO in decreasing order of influence on oxidation resistance are La sub(2)O sub(3), Nd sub(2)O sub(3), Sm sub(2)O sub(3) and Gd sub(2)O sub(3). SEM investigations of the oxide scale morphology revealed that the improved resistance is probably due to the formation of a thin layer of fine grained compact Cr sub(2)O sub(3) and the higher adhesion of the scale to its increased plasticity. (author)

Extremely fine structured cathode for solid oxide fuel cells using Sr-doped LaMnO3 and Y2O3-stabilized ZrO2 nano-composite powder synthesized by spray pyrolysis

Science.gov (United States)

Shimada, Hiroyuki; Yamaguchi, Toshiaki; Sumi, Hirofumi; Nomura, Katsuhiro; Yamaguchi, Yuki; Fujishiro, Yoshinobu

2017-02-01

A solid oxide fuel cell (SOFC) for high power density operation was developed with a microstructure-controlled cathode using a nano-composite powder of Sr-doped LaMnO3 (LSM) and Y2O3-stabilized ZrO2 (YSZ) synthesized by spray pyrolysis. The individual LSM-YSZ nano-composite particles, formed by crystalline and amorphous nano-size LSM and YSZ particles, showed spherical morphology with uniform particle size. The use of this powder for cathode material led to an extremely fine microstructure, in which all the LSM and YSZ grains (approximately 100-200 nm) were highly dispersed and formed their own network structures. This microstructure was due to the two phase electrode structure control using the powder, namely, nano-order level in each particle and micro-order level between particles. An anode-supported SOFC with the LSM-YSZ cathode using humidified H2 as fuel and ambient air as oxidant exhibited high power densities, such as 1.29 W cm-2 under a voltage of 0.75 V and a maximum power density of 2.65 W cm-2 at 800 °C. Also, the SOFC could be stably operated for 250 h with no degradation, even at a high temperature of 800 °C.

Preparation of Er"3"+:Y_3Al_5O_1_2/KNbO_3 composite and application in innocent treatment of ketamine by using sonocatalytic decomposition method

International Nuclear Information System (INIS)

Zhang, Hongbo; Wei, Chunsheng; Huang, Yingying; Li, Guanshu; Wu, Qiong; Wang, Jun; Song, Youtao

2016-01-01

Highlights: • Upconversion luminescence agent Er:YAG can enhance sonocatalytic activity of KNbO_3. • Harmless of narcotic drugs was achieved through sonocatalytic destruction. • Possible sonocatalytic destruction mechanism on narcotic drugs was proposed. - Abstract: A novel sonocatalyst, Er"3"+:Y_3Al_5O_1_2/KNbO_3 composite, was synthesized, and then, characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). In order to evaluate the sonocatalytic activity of prepared Er"3"+:Y_3Al_5O_1_2/KNbO_3 composite, the sonocatalytic degradation of ketamine, a kind of narcotic drug, was studied. In addition, some influencing factors such as mass ratio, heat-treated temperature and heat-treated time on the sonocatalytic activity of prepared Er"3"+:Y_3Al_5O_1_2/KNbO_3 powders and ultrasonic irradiation time on the sonocatalytic degradation of ketamine were examined by using GC–MS machine. The experimental results showed that the Er"3"+:Y_3Al_5O_1_2/KNbO_3 composite is a good sonocatalyst in the field of ultrasonic chemistry and the sonocatalytic degradation was an effective method for the innocent treatment of ketamine.

Síntesis y Caracterización de Ag2Cu2O3, el primer óxido de cobre y plata

Directory of Open Access Journals (Sweden)

Gómez-Romero, P.

2000-06-01

Full Text Available Despite the crystal-chemical similarities between copper and silver ions, there is no known silver copper oxide, neither natural nor synthetic. In this work, we present the synthesis at room-temperature of the first silver copper oxide of formula Ag2Cu2O3 (tetragonal, a=5.8857(3Å, c=10.6868(7Å, space group I41/amd, Z=4. It should be noted that the thermal stability of this new oxide is enhanced with respect to Ag2O or even CuO. The structure consists of alternating chains of edge-sharing square planar Cu(II and zigzag chains of linearly coordinated Ag(I ions.A pesar de las similitudes cristaloquímicas entre los iones de cobre y los de plata, no existe ningún óxido mixto de cobre y plata ni natural ni sintético. En este trabajo se presenta la síntesis a bajas temperaturas del primer óxido mixto de cobre y plata, de fórmula Ag2Cu2O3 (tetragonal, a=5.8857(3Å, c=10.6868(7Å, grupo espacial I41/amd, Z=4. Este óxido posee una estabilidad térmica superior a los correspondientes óxidos de cobre y de plata. Contiene cadenas de iones Cu(II cuadrado-planos que alternan con cadenas en zig-zag de Ag(I con coordinación lineal.

Effect of Rare Earth Y on Properties of Nanosized 90W-7Ni-3Fe Composite Powder Fabricated by Spray Drying-Hydrogen Reduction

Directory of Open Access Journals (Sweden)

Y.-Z. Ma

2008-01-01

Full Text Available (W,Ni,Fe composite oxide powder synthesized by spray drying was reduced at 700∘C for 90 minutes in H2 atmosphere. The effect of rare earth Y on H2 reduction of (W,Ni,Fe composite oxide powder was studied. Phase composition, crystalline size, and particle morphology of the reduced powder have been measured by X-ray diffraction and scanning electron microscope (SEM. Fsss particle size and special surface area of the reduced powder were also measured and analyzed. The result showed that new phase Y(Ni0.75W0.25O3 appeared in the reduced powder and particle morphology was nearly spherical or polyhedron by Y additions. The higher the rare earth element content was, the bigger the influencing on particle morphology was. When the rare earth Y content was under 0.8%, with the increase of the rare earth element content, dBET, Fsss, and crystal sizes of the reduced powder decreased greatly.

Y-Ba-Cu-O superconducting film on oxidized silicon

International Nuclear Information System (INIS)

Gupta, R.P.; Khokle, W.S.; Dubey, R.C.; Singhal, S.; Nagpal, K.C.; Rao, G.S.T.; Jain, J.D.

1988-01-01

We report thick superconducting films of Y-Ba-Cu-O on oxidized silicon substrates. The critical temperatures for onset and zero resistance are 96 and 77 K, respectively. X-ray diffraction analysis predicts 1, 2, 3 composition and orthorhombic phase of the film

Compressive strain-dependent bending strength property of Al2O3-ZrO2 (1.5 mol% Y2O3) composites performance by HIP

International Nuclear Information System (INIS)

Reyes-Rojas, A.; Esparza-Ponce, H.; De la Torre, S.D.; Torres-Moye, E.

2009-01-01

Nanometric powders and sintered ceramics of Al 2 O 3 -ZrO 2 (1.5 mol% Y 2 O 3 ) prepared by hot isostatic pressing HIP have been studied. A detailed crystallographic study has been performed through X-ray diffraction, Williamson-Hall method, Rietveld method and high-resolution electron microscopy HREM analysis. The crystallographic structure data, such as domain size, lattice parameters, wt% phase, and micro-strain direction have been obtained using Rietveld refinement and Williamson-Hall methods. The results revealed that the compressive strain (ε) increased from 0.56 to 1.18 (10 -3 ) as the t-ZrO 2 content increased too. The HREM interface study conducted along the [0 0 0 1]Al 2 O 3 ||[0 0 1]ZrO 2 zone axis revealed a micro-strain lattice distortion accumulated at the grain boundary due to the ZrO 2 martensitic phase transformation on cooling, t-ZrO 2 grains coalescence and to the grain growth of α-Al 2 O 3 which cause elongated tetragonal crystals. Micro-strain lattice distortion is adjusted by the shear displacements of the planes (1 1 0) and (11-bar0) along [1-bar10] and [1-bar1-bar0] crystallographic directions, respectively; these planes are arrested by the (101-bar0) alumina plane. In this case, semi-coherent interfaces were observed along the grain boundary. It is verified that the bending strength increased in connection with the strain accumulation and amount of tetragonal structure

Adhesion of Y2O3-Al2O3-SiO2 coatings to typical aerospace substrates

International Nuclear Information System (INIS)

Marraco-Borderas, C.; Nistal, A.; Garcia, E.; Sainz, M.A.; Martin de la Escalera, F.; Essa, Y.; Miranzo, P.

2016-01-01

High performance lightweight materials are required in the aerospace industry. Silicon carbide, carbon fiber reinforced carbon and slicon carbide composites comply with those requirements but they suffer from oxidation at the high temperature of the service conditions. One of the more effective approaches to prevent this problem is the use of protecting ceramic coatings, where the good adhesion between substrates and coatings are paramount to guarantee the optimal protection performance. In the present work, the adhesion between those substrates and glass coatings of the Y2O3-Al2O3-SiO2 system processed by oxyacetylene flame spraying is analyzed. Increasing load scratch tests are employed for determining the failure type, maximum load and their relation with the elastic and mechanical properties of the coatings. The results points to the good adhesion of the coatings to silicon carbide and carbon fibre reinforced silicon carbide while the carbon fiber reinforced carbon is not a suitable material to be coated. (Author)

Thermochemical characteristics of La n+1Ni nO3n+1 oxides

International Nuclear Information System (INIS)

Bannikov, D.O.; Safronov, A.P.; Cherepanov, V.A.

2006-01-01

Lanthanum nickelates: La 2 NiO 4+δ , La 3 Ni 2 O 7-δ , La 4 Ni 3 O 10-δ and LaNiO 3-δ the members of Ruddlesden-Popper series La n+1 Ni n O 3n+1 were prepared using citrate route. Dissolution enthalpies of complex oxides as well as a number of subsidiary substances were measured by means of Calvet calorimeter in 1 M solution of hydrochloric acid at 25 deg. C. The dissolution scheme of complex oxides in hydrochloric acid was proposed and enthalpies of formation of the complex oxides from binary oxides were calculated considering oxygen nonstoichiometry of these substances. Enthalpies of step-by-step oxidation were evaluated. Partial enthalpy contribution of LaO layers was calculated endothermic equals to 30.9 J/mol while partial enthalpy contribution of perovskite LaNiO 3 layers was negative equals to -97.0 J/mol. Enthalpy of formation of any complex oxide of Ruddlesden-Popper series fits very well to the linear regression based on these values

Oxidation of primary amines to oximes with molecular oxygen using 1,1-diphenyl-2-picrylhydrazyl and WO3/Al2O3 as catalysts.

Science.gov (United States)

Suzuki, Ken; Watanabe, Tomonari; Murahashi, Shun-Ichi

2013-03-15

The oxidative transformation of primary amines to their corresponding oximes proceeds with high efficiency under molecular oxygen diluted with molecular nitrogen (O2/N2 = 7/93 v/v, 5 MPa) in the presence of the catalysts 1,1-diphenyl-2-picrylhydrazyl (DPPH) and tungusten oxide/alumina (WO3/Al2O3). The method is environmentally benign, because the reaction requires only molecular oxygen as the terminal oxidant and gives water as a side product. Various alicyclic amines and aliphatic amines can be converted to their corresponding oximes in excellent yields. It is noteworthy that the oxidative transformation of primary amines proceeds chemoselectively in the presence of other functional groups. The key step of the present oxidation is a fast electron transfer from the primary amine to DPPH followed by proton transfer to give the α-aminoalkyl radical intermediate, which undergoes reaction with molecular oxygen and hydrogen abstraction to give α-aminoalkyl hydroperoxide. Subsequent reaction of the peroxide with WO3/Al2O3 gives oximes. The aerobic oxidation of secondary amines gives the corresponding nitrones. Aerobic oxidative transformation of cyclohexylamines to cyclohexanone oximes is important as a method for industrial production of ε-caprolactam, a raw material for Nylon 6.

Mechanical properties of tungsten alloys with Y2O3 and titanium additions

International Nuclear Information System (INIS)

Aguirre, M.V.; Martin, A.; Pastor, J.Y.; LLorca, J.; Monge, M.A.; Pareja, R.

2011-01-01

In this research the mechanical behaviour of pure tungsten (W) and its alloys (2 wt.% Ti-0.47 wt.% Y 2 O 3 and 4 wt.% Ti-0.5 wt.% Y 2 O 3 ) is compared. These tungsten alloys, have been obtained by powder metallurgy. The yield strength, fracture toughness and elastic modulus have been studied in the temperature interval of 25 deg. C to 1000 deg. C. The results have shown that the addition of Ti substantially improves the bending strength and toughness of W, but it also dramatically increases the DBTT. On the other hand, the addition of 0.5% Y 2 O 3 , is enough to improve noticeably the oxidation behaviour at the higher temperatures. The grain size, fractography and microstructure are studied in these materials. Titanium is a good grain growth inhibitor and effective precursor of liquid phase in HIP. The simultaneous presence of Y 2 O 3 and Ti permits to obtain materials with low pores presence.

Detection of nanocrystallinity by X-ray absorption spectroscopy in thin film transition metal/rare-earth atom, elemental and complex oxides

International Nuclear Information System (INIS)

Edge, L.F.; Schlom, D.G.; Stemmer, S.; Lucovsky, G.; Luning, J.

2006-01-01

Nanocrystallinity has been detected in the X-ray absorption spectra of transition metal and rare-earth oxides by (i) removal of d-state degeneracies in the (a) Ti and Sc L 3 spectra of TiO 2 and LaScO 3 , respectively, and (b) O K 1 spectra of Zr(Hf)O 2 , Y 2 O 3 , LaScO 3 and LaAlO 3 , and by the (ii) detection of the O-atom vacancy in the O K 1 edge ZrO 2 -Y 2 O 3 alloys. Spectroscopic detection is more sensitive than X-ray diffraction with a limit of ∼2 nm as compared to >5 mm. Other example includes detection of ZrO 2 nanocrystallinity in phase-separated Zr(Hf) silicate alloys

Photoluminescent and Thermoluminescent Studies of Dy3+ and Eu3+ Doped Y2O3 Phosphors.

Science.gov (United States)

Verma, Tarkeshwari; Agrawal, Sadhana

2018-01-01

Eu 3+ doped and Dy 3+ codoped yttrium oxide (Y 2 O 3 ) phosphors have been prepared using solid-state reaction technique (SSR). The prepared phosphors were characterized by X-ray diffractometer (XRD), energy dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR) techniques. Photoluminescence (PL) and Thermoluminescence (TL) properties were studied in detail. PL emission spectra were recorded for prepared phosphors under excitation wavelength 254 nm, which show a high intense peak at 613 nm for Y 2 O 3 :Dy 3+ , Eu 3+ (1:1.5 mol %) phosphor. The correlated color temperature (CCT) and CIE analysis have been performed for the synthesized phosphors. TL glow curves were recorded for Eu 3+ doped and Dy 3+ codoped phosphors to study the heating rate effect and dose response. The kinetic parameters were calculated using peak shape method for UV and γ exposures through computerized glow curve deconvolution (CGCD) technique. The phosphors show second order kinetics and activation energies varying from 5.823 × 10 - 1 to 18.608 × 10 - 1  eV.

Pulsed laser deposition of YBCO coated conductor using Y2O3 as the seed and cap layer

International Nuclear Information System (INIS)

Barnes, P N; Nekkanti, R M; Haugan, T J; Campbell, T A; Yust, N A; Evans, J M

2004-01-01

Although a variety of buffer layers have been routinely reported, a standard architecture commonly used for the Y Ba 2 Cu 3 O 7-x (YBCO) coated conductor is Y BCO/CeO 2 /Y SZ/CeO 2 /substrate or Y BCO/CeO 2 /Y SZ/Y 2 O 3 /substrate where ceria is typically the cap layer. CeO 2 is generally used as only a seed (or cap layer) since cracking within the film occurs in thicker CeO 2 layers due to the stress of lattice mismatching. Y 2 O 3 has been proposed as a seed and as a cap layer but usually not for both in a given architecture, especially with all layers deposited in situ. Yttrium oxide films grown on nickel by electron beam evaporation processes were found to be dense and crack free with good epitaxy. In this report, pulsed laser deposition (PLD) of Y 2 O 3 is given where Y 2 O 3 serves as both the seed and cap layer in the YBCO architecture. A comparison to PLD CeO 2 is provided. Deposited layers of the YBCO coated conductor are also grown by laser ablation. Initial deposition resulted in specimens on textured Ni substrates with current densities of more than 1 MA cm -2 at 77 K, self-field

Effects of the addition of H{sub 2}O and NH{sub 4}OH in the electrical properties of thin films of Y{sub 2}O{sub 3} deposited by pyrolytic spray; Efectos de la adicion de H{sub 2}O y NH{sub 4}OH en las propiedades electricas de peliculas delgadas de Y{sub 2}O{sub 3} depositadas por rocio pirolitico

Energy Technology Data Exchange (ETDEWEB)

Herrera S, H.J.; Alarcon F, G.; Aguilar F, M. [CICATA-IPN, Legaria 694, Col. Irrigacion, 11500 Mexico D.F. (Mexico); Falcony, C. [CINVESTAV-IPN, 07000 Mexico D.F. (Mexico); Garcia H, M.; Guzman M, J. [IIM-UNAM, A.P. 70-360, 04510 Mexico D.F. (Mexico); Araiza I, J.J. [UAZ, 98060 Zacatecas (Mexico)

2005-07-01

In this work we studied the electrical properties of yttrium oxide thin films obtained by spray pyrolysis from Y(acac){sub 3} and N,N-DMF. The films were deposited on Si(100) substrates at temperatures of 400, 450, 500 and 550 C. The electrical characteristic of the films was improved when a mist of H{sub 2}O and/or NH{sub 4}0H was simultaneously added to the deposition system. Current and capacitance versus voltage measurements were obtained when the Y{sub 2}O{sub 3} films were integrated in MOS (Metal-Oxide-Semiconductor) structures. Y{sub 2}O{sub 3} films with a dielectric constant up to 15 were obtained. The films can stand electric fields up to 2 MV/cm. An interface state density in the range of 10{sup 10}-10{sup 11} cm{sup -2} eV{sup -1} was measured at midgap from the high and low frequency capacitance measurements. (Author)

Rare earth metals, rare earth hydrides, and rare earth oxides as thin films

International Nuclear Information System (INIS)

Gasgnier, M.

1980-01-01

The review deals with pure rare earth materials such as rare earth metals, rare earth hydrides, and rare earth oxides as thin films. Several preparation techniques, control methods, and nature of possible contaminations of thin films are described. These films can now be produced in an extremely well-known state concerning chemical composition, structure and texture. Structural, electric, magnetic, and optical properties of thin films are studied and discussed in comparison with the bulk state. The greatest contamination of metallic rare earth thin films is caused by reaction with hydrogen or with water vapour. The compound with an f.c.c. structure is the dihydride LnH 2 (Ln = lanthanides). The oxygen contamination takes place after annealing at higher temperatures. Then there appears a compound with a b.c.c. structure which is the C-type sesquioxide C-Ln 2 O 3 . At room atmosphere dihydride light rare earth thin films are converted to hydroxide Ln(OH) 3 . For heavy rare earth thin films the oxinitride LnNsub(x)Osub(y) is observed. The LnO-type compound was never seen. The present review tries to set the stage anew for the investigations to be undertaken in the future especially through the new generations of electron microscopes

Determination of oxygen in ternary uranium oxides by a gravimetric alkaline earth addition method

International Nuclear Information System (INIS)

Fujino, T.; Tagawa, H.

1979-01-01

The applicability of a gravimetric method based on alkaline earth metal addition for the determination of oxygen in ternary uranium oxides of the tupe M-U-O (M=La, Ce and Th) is described. The oxide sample is mixed with MgO or Basub(2.8)UOsub(5.8) and heated in air under suitable conditions. Because uranium is completely oxidized to the hexavalent state during the reaction, oxygen can be determined from the weight change. Oxygen in Lasub(y)Usub(1-y)Osub(2+x) is determined up to y = 0.8 with a standard deviation for x of +- 0.006 with MgO. For Thsub(y)Usub(1-y)Osub(2+x) the value of x is determined with Basub(2.8)UOsub(5.8) with a standard deviation of +- 0.01 at y = 0.8. For Cesub(y)Usub(1-y)Osub(2+x), the method can be applied only for low cerium concentrations where y = 0-0.2; the value for x with Basub(2.8)UOsub(5.8) at y = 0.2 showed a standard deviation of +- 0.002. (Auth.)

Novel oxide buffer approach for GaN integration on Si(111) platform through Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3} bi-layer

Energy Technology Data Exchange (ETDEWEB)

Tarnawska, Lidia

2012-12-19

Motivation: Preparation of GaN virtual substrates on large-scale Si wafers is intensively pursued as a cost-effective approach for high power/high frequency electronics (HEMT's etc.) and optoelectronic applications (LED, LASER). However, the growth of high quality GaN layers on Si is hampered by several difficulties mainly related to a large lattice mismatch (-17%) and a huge difference in the thermal expansion coefficient (56%). As a consequence, GaN epitaxial layers grown on Si substrates show a high number of defects (threading dislocations etc.), which severely deteriorate the overall quality of the GaN films. Additionally, due to the different thermal expansion coefficients of the substrate and the film, um-thick GaN layers crack during post-growth cooling. To solve these integration problems, different semiconducting (e.g. AlN, GaAs, ZnO, HfN) and insulating (e.g. Al{sub 2}O{sub 3}, MgO, LiGaO{sub 2}) buffer layers, separating the Si substrate from the GaN film, are applied. Goal: In this thesis, a novel buffer approach for the integration of GaN on Si is proposed and investigated. The new approach employs Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3} bilayer templates as a step-graded buffer to reduce the lattice mismatch between GaN and the Si(111) substrate. According to the bulk crystal lattices, since the Y{sub 2}O{sub 3} has an in-plane lattice misfit of -2% to Si, Sc{sub 2}O{sub 3} -7% to Y{sub 2}O{sub 3}, the lattice misfit between GaN and the substrate can be theoretically reduced by about 50% from -17% (GaN/Si) to -8% (GaN/Sc{sub 2}O{sub 3}). Experimental: The GaN/Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3}/Si(111) heterostructures are prepared in a multichamber molecular beam epitaxy system on 4 inch Si(111) wafers. In order to obtain complete information on the structural quality of the oxide buffer as well as the GaN layer, synchrotron- and laboratory-based X-ray diffraction, transmission electron microscopy and photoluminescence measurements are performed. The

Solid electrolytes based on {1 − (x + y}ZrO2-(xMgO-(yCaO ternary system: Preparation, characterization, ionic conductivity, and dielectric properties

Directory of Open Access Journals (Sweden)

Nazli Zeeshan

2018-01-01

Full Text Available Different composition of composite material of zirconium dioxide co-doped with magnesium oxide [MgO(x] and calcium oxide [CaO(y] according to the general molecular formula {1 − (x + y}ZrO2-(xMgO-(yCaO were prepared by co-precipitation method and characterized by different techniques, such as XRD, FTIR, TG-DTA, and SEM. Co-doping was conducted to enhance the ionic conductivity, as mixed system show higher conductivity than the single doped one. Arrhenius plots of the conductance revealed that the co-doped composition “6Mg3Ca” has a higher conductivity with a minimum activation energy of 0.003 eV in temperature range of 50–190 °C. With increasing temperature, dielectric constant value increased; however, with increasing frequency it shows opposite trend. Co-doped composition C2 exhibit higher conductivity compared to C3, owing to the concentration of Mg content (0–6%; the conductivity decreases thereafter. Zirconium oxide was firstly used for medical purpose in orthopaedics, but currently different type of zirconia-ceramic materials has been successfully introduced into the clinic to fix the dental prostheses.

Luminescence properties of Y2O3:Bi3+, Yb3+ co-doped phosphor for application in solar cells

Science.gov (United States)

Lee, E.; Kroon, R. E.; Terblans, J. J.; Swart, H. C.

2018-04-01

Bismuth (Bi3+) and ytterbium (Yb3+) co-doped yttrium oxide (Y2O3) phosphor powder was successfully synthesised using the co-precipitation technique. The X-ray diffraction (XRD) patterns confirmed that a single phase cubic structure with a Ia-3 space group was formed. The visible emission confirmed the two symmetry sites, C2 and S6, found in the Y2O3 host material and revealed that Bi3+ ions preferred the S6 site as seen the stronger emission intensity. The near-infrared (NIR) emission of Yb3+ increased significantly by the presence of the Bi3+ ions when compared to the singly doped Y2O3:Yb3+ phosphor with the same Yb3+ concentration. An increase in the NIR emission intensity was also observed by simply increasing the Yb3+ concentration in the Y2O3:Bi3+, Yb3+ phosphor material where the intensity increased up to x = 5.0 mol% of Yb3+ before decreasing due to concentration quenching.

Method of forming an oxide superconducting thin film having an R1A2C3 crystalline phase over an R2A1C1 crystalline phase

International Nuclear Information System (INIS)

Lelental, M.; Romanofsky, H.J.

1992-01-01

This patent describes a process which comprises forming a mixed rare earth alkaline earth copper oxide layer on a substrate and converting the mixed rare earth alkaline earth copper oxide layer to an electrically conductive layer. It comprises crystalline R 1 A 2 C 3 oxide phase by heating in the presence of oxygen, wherein rare earth and R is in each instance chosen from among yttrium, lanthanum, samarium, europium, gadolinium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium and alkaline earth and A is in each instance chosen from among calcium, strontium and barium, characterized in that a crystalline R 2 A 1 C 1 oxide phase is first formed as a layer on the substrate and the crystalline R 1 A 2 C 3 oxide phase is formed over the crystalline R 2 A 1 C 1 oxide phase by coating a mixed rare earth alkaline earth copper oxide on the crystalline R 2 A 1 C 1 oxide phase and heating the mixed rare earth alkaline earth copper oxide to a temperature of at least 1000 degrees C

Mechanical properties of Y2O3-doped W-Ti alloys

International Nuclear Information System (INIS)

Aguirre, M.V.; Martin, A.; Pastor, J.Y.; LLorca, J.; Monge, M.A.; Pareja, R.

2010-01-01

W and W alloys are currently considered promising candidates for plasma facing components in future fusion reactors but most of the information on their mechanical properties at elevated temperature was obtained in the 1960s and 1970s. In this investigation, the strength and toughness of novel Y 2 O 3 -doped W-Ti alloys manufactured by powder metallurgy were measured from 25 o C up to 1000 o C in laboratory air and the corresponding deformation and failure micromechanisms were ascertained from analyses of the fracture surfaces. Although the materials were fairly brittle at ambient temperature, the strength and toughness increased with temperature and Ti content up to 600 o C. Beyond this temperature, oxidation impaired the mechanical properties but the presence of Y 2 O 3 enhanced the strength and toughness retention up to 800 o C.