EXAFS analysis and reinvestigation of the structure of a defect-fluorite-type compound, Y{sub 3}TaO{sub 7}
Journal Article
·
· Journal of Solid State Chemistry
- Tokyo Inst. of Technology, Yokohama (Japan); and others
The compositional and positional disorder of constituent atoms in Y{sub 3}TaO{sub 7} crystals with the defect-fluorite-type structure have been elucidated through analysis of the extended X-ray absorption fine structure (EXAFS) and reinvestigation of the crystal structure with single crystal X-ray diffraction data. EXAFS analysis based on the single shell model gave mean Y-O and Ta-O bond distances of 2.29 and 1.98 {angstrom}, respectively. X-ray diffraction study revealed that the structure is essentially of the fluorite type, though Y atoms are displaced along (111) by 0.219(5) {angstrom} from the position of Ca in fluorite, and half of the oxygen atoms are also displaced along (001) by 0.54(4) {angstrom} from the position of F. The Ta atom is surrounded by at most eight oxygen atoms with Ta-O bond distance of 2.01(2) {angstrom}, while the Y atom is surrounded by at most seven oxygen atoms with mean Y-O bond distance of 2.277(7) {angstrom}. The mean bond distances and the coordination numbers of metal atoms obtained by X-ray diffraction are generally consistent with those obtained by EXAFS analysis. Most oxygen vacancies in Y{sub 3}TaO{sub 7} appear to concentrate around Y atoms. The local structure around Y atoms in Y{sub 3}TaO{sub 7} is similar to that in Y{sub 2}O{sub 3}. Crystal data for Y{sub 3}TaO{sub 7} are as follows; cubic, Fm3m, a = 5.2553(3) {angstrom} at 24{degrees}C, Z =1, and D{sub x} = 6.41 g/cm{sup 3}.
- OSTI ID:
- 552728
- Journal Information:
- Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 114; ISSN 0022-4596; ISSN JSSCBI
- Country of Publication:
- United States
- Language:
- English
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