The structures of intergrowth tungsten bronzes of Ba, Sn, Pb, and Sb

Abstract

The structures of intergrowth tungsten bronzes ( ITB) of compositions Ba 0.04WO 3, Sn 0.04WO 3, Pb 0.04WO 3, Sn 0.18WO 3, and Sb 0.25WO 3 have been deduced from high-resolution electron microscope images. Both the Pb 0.04, Sn 0.04, and Ba 0.04, ITB phases consist of single rows of hexagonal tunnels occupied by Pb, Sn, or Ba atoms intergrown in a WO 3-like matrix. The Sb 0.25, ITB phase is composed of similar rows of Sb-containing single hexagonal tunnels, the centers of which are separated by a WO 3-like matrix only two octahedra in thickness. The structure of the Sn 0.18, ITB phase consists of double rows of hexagonal tunnels containing Sn atoms joined by a single strip of WO 3-like octahedra. The structures are compared with the structures of other known ITB phases and the nonstoichiometric behavior of these phases is discussed.