X‐Ray Study of Phase Transformations in Some Rare‐Earth Oxide Systems

1962 ◽  
Vol 36 (2) ◽  
pp. 298-301 ◽  
Author(s):  
R. L. Mozzi ◽  
O. J. Guentert
Keyword(s):  
Rare Earth ◽  
Phase Transformations ◽  
Rare Earth Oxide ◽  
Oxide Systems ◽  
X Ray

Structure and Chemistry across Interfaces at Nanoscale of a Ge Quantum Well Embedded within Rare Earth Oxide Layers

2011 ◽  
Vol 17 (5) ◽  
pp. 759-765 ◽  
Author(s):  
Tanmay Das ◽  
Somnath Bhattacharyya
Keyword(s):  
Rare Earth ◽  
Solid Phase ◽  
Rare Earth Oxide ◽  
Dark Field ◽  
X Ray ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Annular Dark Field ◽  
Electron Energy Loss ◽  
Field Imaging

AbstractStructure and chemistry across the rare earth oxide-Ge interfaces of a Gd2O3-Ge-Gd2O3 heterostructure grown on p-Si (111) substrate using encapsulated solid phase epitaxy method have been studied at nanoscale using various transmission electron microscopy methods. The structure across both the interfaces was investigated using reconstructed phase and amplitude at exit plane. Chemistry across the interfaces was explored using elemental mapping, high-angle annular dark-field imaging, electron energy loss spectroscopy, and energy dispersive X-ray spectrometry. Results demonstrate the structural and chemical abruptness of both the interfaces, which is most essential to maintain the desired quantum barrier structure.

Structural analysis of excess-anion C-type rare earth oxide: a case study with Gd1−xCexO1.5+x/2(x= 0.20 and 0.40)

2003 ◽  
Vol 36 (4) ◽  
pp. 1082-1084 ◽  
Author(s):  
V. Grover ◽  
S. N. Achary ◽  
A. K. Tyagi
Keyword(s):  
Rare Earth ◽  
Structural Analysis ◽  
Metal Ion ◽  
Rare Earth Oxide ◽  
Charge Balance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Lattice Space

Structural analysis of anion-rich C-type Gd2O3was carried by the Rietveld refinement of the powder X-ray diffraction data for compositions Gd0.8Ce0.2O1.60and Gd0.6Ce0.4O1.70. Both compounds have a body-centred cubic lattice (space groupIa\bar{3}, No. 206,Z= 32) with unit-cell parameters of 10.8488 (1) and 10.8542 (1) Å, respectively. Both of these compounds are iso-structural with the C-type rare earth oxides, with excess anions as required for charge balance. The structural analysis reveals that there are two different kinds of metal ion site, namely 8b(M1) and 24d(M2), and two different kinds of anion sites, namely 48e(O1) and 16c(O2). The excess anions occupy the 16c(xxx) sites. The two metal ions each form an approximately eightfold-coordination polyhedron with O1 and O2. The details of these two compositions are explained and compared with both the CeO2structure and the Gd2O3structure,i.e.the end member.

scholarly journals Subsolidus Phase Relationships in Si3N4-AlN-Rare-Earth Oxide Systems

1986 ◽  
Vol 69 (10) ◽  
pp. C-241-C-242 ◽  
Author(s):  
Zehn-Kun Huang ◽  
Tseng-Ying Tien ◽  
Tung-Sheng Yen
Keyword(s):  
Rare Earth ◽  
Rare Earth Oxide ◽  
Oxide Systems ◽  
Subsolidus Phase ◽  
Phase Relationships

Synthesis and Characterization of Zirconium Oxide Systems with Yttrium Rich Rare Earth Concentrate Additives

2014 ◽  
Vol 798-799 ◽  
pp. 174-181
Author(s):  
Paola Cristina Cajas ◽  
R. Muñoz ◽  
A.C. Rodríguez ◽  
J.E. Rodríguez-Páez ◽  
C.R.M. da Silva
Keyword(s):  
Rare Earth ◽  
Ionic Conductivity ◽  
Zirconium Oxide ◽  
Complex Impedance ◽  
Rare Earth Oxide ◽  
Precipitation Method ◽  
Oxide Systems ◽  
Electric Behavior ◽  
Controlled Precipitation

In this work, the yttrium rich rare earth concentrate (Re2(CO3)3) was used as additive aiming stabilization of cubic an tetragonal phases at commercial zirconium oxide with 3% mol of yttrium oxide. The use of high purity rare earth oxide as additive is being commercially used and this work aims to demonstrate the potential use of lower cost additives to produce solid electrolyte for oxygen sensors and fuel cell applications. The powders for the additive production were synthesized by the controlled precipitation method. After synthesis, the powders were de-agglomerated using mechanical grinding and mixed to commercial zirconia to produce the compositions ZrO2:3% Mol Y2O3:ƞ % Mol Re2O3 (ƞ=3,4,5,6), followed by uniaxial press and sintering at 1500 0C in two hours. The obtained sintered densities were above 96% of theoretical. X-Ray diffractometric analysis and Rietweld refinement demonstrated the stabilization of cubic and tetragonal phases for all samples with yttrium rich rare earth concentrate additives. Finally the electric behavior of the evaluated samples was carried out with complex impedance spectroscopy, showing conductivity improvement for samples with the chosen additive. At 500 0C the sample A-9% had a conductivity of 1,11E-3Ω-1.cm-1, well above of the sample without additive with conductivity 5,88E-4Ω1.cm-1, indicative that use of yttrium rich rare earth concentrate as additive increases considerably the ionic conductivity of comercial zirconium oxide. Key words: rare earth concentrate, controlled precipitation, ionic conductivity

Evaluation of the Effect of Heavy Rare Earth Elements on Electrical Resistivity of Zirconia-Yttria Ceramics

2005 ◽  
Vol 498-499 ◽  
pp. 305-310 ◽  
Author(s):  
Dolores Ribeiro Ricci Lazar ◽  
Valter Ussui ◽  
E.N.S. Muccillo ◽  
Ana Helena A. Bressiani ◽  
José Octavio A. Pascoal
Keyword(s):  
Electrical Resistivity ◽  
Rare Earth ◽  
Rare Earths ◽  
Chemical Elements ◽  
Resistivity Measurement ◽  
Density Measurement ◽  
Rare Earth Oxide ◽  
Electrical Resistivity Measurement ◽  
Heavy Rare Earth ◽  
Oxide Systems

The use of yttria concentrates was investigated in this study for synthesis and processing of zirconia based ceramics applied as solid electrolyte materials. Terbium, dysprosium, holmium, erbium and ytterbium are the chemical elements, classified as heavy rare earths, that can be found in those concentrates due to their association with yttrium ores. The ceramic characteristics were compared to zirconia-yttria and zirconia-yttria-heavy rare earth oxide systems, containing 3 and 9 mol% of dopant. Powders were prepared by the coprecipitation route and ceramic processing conditions were established to attain relative densities up to 95%. The characterization of assintered pellets was performed by apparent density measurement by Archimedes method, X-ray diffraction, scanning electron microscopy and electrical resistivity measurement by impedance spectroscopy. It was observed that the presence of heavy rare earths in a concentrate containing 85 wt% of yttria has no significant influence on the total ionic resistivity of zirconia based ceramics.

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