Silver ion-exchanged lithium tantalate Li1-xAgxTaO3: Identification of perovskite-related phases by electron diffraction

Abstract

Electron diffraction results are presented which allow the structural parameters of the perovskiterelated structure of AgTaO3 to be identified. The structure is essentially trigonal (a = 5.548 Å, c = 13.658 Å) with approximate spacegroup [image omitted] (or R3c), although there may be additional weak symmetry operations lowering the true symmetry to orthorhombic or monoclinic. Commensurate and incommensurate superstructure phenomena are interpreted in terms of coherent intergrowths of the perovskite-related phases, involving octahedral tilts about pseudocubic 〈111〉 axes, having symmetries [image omitted], Pnma, I4/mmm and Im3.