Structural characterization and temperature-dependent behavior of layered tungstates

Abstract

Layered tungstates are an intriguing class of perovskite-like structures with a range of relevant properties, e.g. (photo-)catalytic activity and ion conduction. In this thesis, the Aurivillius-type bismuth tungstate Bi2WO6 and the Ruddlesden-Popper-type hydrotungstate H2W2O7 are structurally characterized in terms of phase transitions, distortion and disorder. The scattering characteristics posed major challenges for the accurate structural description of both compounds. In case of the bismuth tungstate, the oxygen coordination could not be described precisely although observable trends indicate additional stages in the already known rich thermomorphism. In case of the hydrotungstate, structure solution attempts on synthesized samples did not lead to unambiguous results due to present disorder but could be related to those recently published by a different group. Overall, the gained insights offer many leads for further studies in the layered tungstate system.