Phase relations and crystal chemistry of solid solution, Sr/sub y/U/sub 1-y/O/sub 2+x/
Solid solutions, Sr/sub y/Y/sub 1-y/O/sub 2+x/, were prepared by heating the mixtures of ..beta..-SrUO/sub 4/, UO/sub 2/, and U/sub 3/O/sub 8/ in either helium or vacuum. When heated in helium at 1300 or 1400/sup 0/C, a single-phase cubic fluorite (face centered cubic, FCC) phase was obtained up to strontium concentration (y of Sr/sub y/U/sub 1-y/O/sub 2+x/) ca. 0.3, although it splits into two fluorite phases around y = 0.03, 0.05, and 0.08 during the relatively slow cooling process. Due to larger x values of Sr/sub y/U/sub 1-y/O/sub 2+x/, for the samples heated at 1200/sup 0/C, a single rhombohedral phase was formed in the range 0.06 less than or equal to y less than or equal to 0.10. The x value and uranium valency in the solids showed steep change at y = 0.03, 0.06, and 0.09, which is presumably related to the stepwise ordering strontium atoms to form the rhombohedral phase. A statistical thermodynamical calculation was made concerning this transition. When heated in vacuum, only the FCC phase was formed below y = 0.15. For this phase, the lattice parameter change was expressed as linear functions of x and y by least-squares fittings. The coefficient of y of these equations was found to be on a straight line irrespective of the valency of the foreign cation if the net change in crystal radius was taken as the variable.
- Research Organization:
- Japan Atomic Energy Research Institute, Ibaraki-ken
- OSTI ID:
- 7249096
- Journal Information:
- J. Solid State Chem.; (United States), Journal Name: J. Solid State Chem.; (United States) Vol. 73:2; ISSN JSSCB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ACTINIDE COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
CHALCOGENIDES
CHEMICAL PREPARATION
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
CUBIC LATTICES
DATA
DISPERSIONS
EXPERIMENTAL DATA
FCC LATTICES
INFORMATION
MATHEMATICAL MODELS
MIXTURES
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
PHASE TRANSFORMATIONS
SOLID SOLUTIONS
SOLUTIONS
STATISTICAL MODELS
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
SYNTHESIS
THERMODYNAMICS
URANIUM COMPOUNDS
URANIUM OXIDES