Studies of the property of ionic conductivity of solid solutions of Ca sub 1 minus x Th sub x F sub 2+2x and Ca sub 1 minus x U sub x F sub 2+2x

Journal Article · Sat Jun 01 04:00:00 EDT 1991 · Journal of Solid State Chemistry; (United States)

DOI:https://doi.org/10.1016/0022-4596(91)90339-J· OSTI ID:6114145

El Omari, M; Reau, J M; Senegas, J ^[1]; Lavel, J P; Frit, B ^[2]

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1. Univ. de Bordeaux I, Talence (France)
2. Univ. de Limoges (France)

A comparative study of the ionic conductivity properties of the solid solutions Ca{sub 1-x}Th{sub x}F{sub 2+2x} (0 {le} x {le} 0.18) and Ca{sub 1-x}U{sub x}F{sub 2+2x} (0 {le} x {le} 0.19) has been undertaken and correlations between the electrical properties and the short-range order within these phases have been established. The model of the processes of clustering proposed for the anion excess CaF{sub 2}-type solid solutions M{sub 1-x}{sup 2+}M{prime}{sub x}{sup 2+{alpha}}F{sub 2+{alpha}x} ({alpha} = 1,2,3) has been applied to the solid solutions Ca{sub 1-x}M{double prime}{sub x}F{sub 2+2x}(M{double prime} = Th, U). The formation of the 1 : 0 : 3 clusters is confirmed when x increases in the composition domain (0.01 {approx lt} x {le} x{sub L}) (x{sub L} : upper limit of substitution rate). Two sublattices of vacancies are located inside the 1 : 0 : 3 clusters (y{sub 1}) and in the immediate neighborhood (y{sub 2}); these are related respectively to the F{double prime} and F{prime}{double prime} interstitial fluoride anions. The Ca{sub 1-x}U{sub x}F{sub 2+2x} phase, involving the smallest tetravalent cation, has a larger number of vacancies y{sub 2} and weaker space constraints for the same substitution rate. It results in better electrical properties for that solid solution than for Ca{sub 1-x}Th{sub x}F{sub 2+2x}. The solid solutions Ca{sub 1-x}M{double prime}{sub x}F{sub 2+2x} (M{double prime} = Th, U) are characterized by the same process of clustering as the solid solutions Ca{sub 1-x}Ln{sub x}F{sub 2+x} (Ln = La, Nd, Gd) involving rare earth substitutional cations of large size.

• OSTI ID: 6114145
• Journal Information: Journal of Solid State Chemistry; (United States), Journal Name: Journal of Solid State Chemistry; (United States) Vol. 92:2; ISSN JSSCB; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400702 -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
ACTINIDE COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ANIONS
CALCIUM COMPOUNDS
CALCIUM FLUORIDES
CALCIUM HALIDES
CATIONS
CHARGED PARTICLES
CHEMICAL PREPARATION
COMPARATIVE EVALUATIONS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DISPERSIONS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
EVALUATION
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
INTERSTITIALS
ION PAIRS
IONIC CONDUCTIVITY
IONS
MATHEMATICAL MODELS
MIXTURES
PHYSICAL PROPERTIES
POINT DEFECTS
SOLID SOLUTIONS
SOLUTIONS
SYNTHESIS
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
THORIUM COMPOUNDS
THORIUM FLUORIDES
URANIUM COMPOUNDS
URANIUM FLUORIDES
VACANCIES