Influence de la nature des ions et sur l'évolution structurale des weberites A₂B₂O₇: les weberites Cd _2−xSr_xSb₂O₇

Abstract

A new series of solid solution Cd2−xSrxSb2O7 (0 ≤ x ≤ 2) of the weberite type has been prepared and characterized. Examination of the weberite structure has revealed the existence of three critical metal–oxygen distances. The proposed ordering of the A ions permits the structural features of these compounds to be explained.

Complex ceramic structures. I. Weberites

“…To date, fluorine-based weberites such as Na 2 B 2+ B 3+ F 7 and Ag 2 B 2+ B 3+ F 7 have attracted most of the attention owing to their interesting magnetic properties (Cosier et al, 1970;Dance et al, 1974;Frenzen et al, 1992;Laligant et al, 1989;Pankhurst et al, 1991;Thompson et al, 1992;Tressaud et al, 1974;Heger, 1973). Investigations on A 2 B 2 O 7 weberites have mainly focused on crystallography because of the close relationship between the weberite and the pyrochlore structures (Cordfunke & Ijdo, 1988;Groen & Ijdo, 1988;Klein et al, 2006;Reading et al, 2002;Astafev et al, 1985;Bonazzi & Bindi, 2007;Desgardin et al, 1976;Grey et al, 2001Grey et al, , 2003Grey & Roth, 2000;Ivanov & Zavodnik, 1990). Both of the structures form three-dimensional BX 6 networks and HTB-like layers.…”

Pyrochlores. XI. High-pressure studies of the antimonates A2Sb2O7 (A = Ca, Sr, Cd) and preparation of the weberite Sr2Bi2O7

“…It contains no provision to account for the existence of the trigonal distortion observed in PbzSb207(P) (which is probably due to the lone pair on PbZ+), for the effect of nonstoichiometry on the symmetry of the crystal structure, or for ordering in solid solutions AZ,A',SbzO7, such as described in ref. 11. How--30f the antirnonates included in Fig.…”