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Neutron diffraction study of the anion-excess fluorite-related Ca/sub 1-x/Th/sub x/F/sub 2+2x/ solid solution

Journal Article · · J. Solid State Chem.; (United States)
The defect structure of Ca/sub 1-x/Th/sub x/F/sub 2+2x/ solid solution (0 less than or equal to x less than or equal to 0.18) has been examined by powder neutron diffraction. Two kinds of interstitials whose respective numbers increase linearly with increasing dopant concentration, can be distinguished: one labeled F'' (x approx. =0.41) is a true interstitial anion, the other noted F'' (x approx. =0.30) can be considered as a relaxed normal F anion. Two models of defect clusters, compatible with the observed distribution of F anions between normal and interstitial sites, and containing, respectively, one and two Th/sup 4 +/ cations, are proposed. In both clusters, Th/sup 4 +/ is 10-fold coordinated. Such clusters, which seem characteristic of large-size dopant cations, are suggested as possible defect-models for the Pb/sub 1-x/Th/sub x/F/sub 2+2x/solid solution.43 references, 6 figures, 3 tables.
Research Organization:
Laboratoire de Chimie Minerale Structurale, Limoges, France
OSTI ID:
5895148
Journal Information:
J. Solid State Chem.; (United States), Journal Name: J. Solid State Chem.; (United States) Vol. 61:3; ISSN JSSCB
Country of Publication:
United States
Language:
English