beta AgVO3 crystal structure and relationships with Ag2V4O11 and delta AgxV2O5

The structure of beta AgVO3 has been determined on single crystal by X ray diffraction techniques. beta AgVO3 crystallizes in the monoclinic system, space group Cm, with a = 18.106(3) Angstrom, b = 3.5787(7) Angstrom, c = 8.043(3) Angstrom, and beta = 104.44(4)degrees. The acentric character of the structure is discussed on the basis of the atomic positions. The beta AgVO3 structure reveals a rather strong three dimensional network made of the vanadium atoms and three silver atoms with their associated oxygen surroundings, [Ag3V4O12](n-)(n). The fourth silver cation, which assumes the electrostatic balance, appears to be inserted in a monocapped trigonal prism allowing its mobility at highest temperatures, Structural relationships between this compound and other silver vanadium oxide bronzes such as Ag2V4O11 and delta AgxV2O5 involves crystallographic shear mechanisms. The existence of a new silver vanadium oxide bronze is discussed. (C) 1996 Academic Press, Inc.