It is demonstrated that the Ag 1؉x V 3 O 8 phase can derive from a sprouting phenomenon easily occurring in the Ag 2 V 4 O 11 vanadate. The oxygen departure rough formula Ag 2 V 4 O 11-y drives to the formation of the title phase for y ؍ 0.16. Single crystals were obtained and fully characterized by X-ray single-crystal techniques. Ag 1.2 V 3 O 8 crystallizes in the monoclinic system, space group P2 1 /m, a ؍ 7.382(5) A s , b ؍ 3.6029(6) A s , c ؍ 12.193(8) A s , ؍ 107.39(6)°, Z ؍ 2, and is isostructural with Li 1؉x V 3 O 8 . Structural relationships with Ag 2 V 4 O 11-y are detailed. It is shown that silver atoms, located between the [V 3 O 8 ] n layers formed by association of two octahedra and a trigonal bipyramid by edge and corner sharing, occupy two crystallographic sites. Electron density computations show that silver atoms move along the [010] direction, explaining the interesting electrochemical properties. Magnetic measurements establish the perfect correspondence between inserted Ag ؉ ions and the V 4؉ yield, giving the formula Ag 1؉y V 5؉ 3-y V 4; y O 8 .
1997 Academic Press
Crystallographic Study
XRD powder data were obtained using a Seifert XRD 3000TT diffractometer with monochromatized CuK radiation ( "1.5418 A s ). X-ray profiles were measured between 2 and 40° in a step-scan mode with a counting time of 10 s and an angular step of 0.01°in .