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Berlin 2005 – scientific programme

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TT: Tiefe Temperaturen

TT 23: Posters Superconductivity, Solids at Low Temperature

TT 23.8: Poster

Monday, March 7, 2005, 14:00–18:00, Poster TU D

Synthesis and Characterization of new RexW1−xO3 Phases — •Ch. Helbig1, B. Rohrmoser1, K. Tröster1, D. Shorokhov1, G. Heymann2, G. Eickerling1, R. Herrmann1, E.-W. Scheidt1, and W. Scherer11CPM, Universität Augsburg, 86135 Augsburg, Germany — 2Department Chemie, LMU, 81377 München, Germany

In this presentation we outline new synthetic routes to the small class of vacancy perovskites M1−xMx′O3 (M, M′ = transition metal) which allows to control their physical properties by variation of the ratio of the metal cations. Employing highly topotactical Chimie Douce methods [1] or alternatively high pressure/high temperature routes [2] we were able to synthesize mixed WO3 and ReO3 phases and characterize them with respect to their crystal chemistry and physical properties. The chosen parent compounds strongly differ in their electronic and structural behavior.The d1-system ReO3 has metallic character and cubic symmetry (Pm3m), whereas the d0-system WO3 is an insulator and displays various structural phase transitions between 1170 K and 230 K. However, the structures of all these WO3 phases can be derived by group-subgroup relationships from the ReO3 structure [3]. For RexW1−xO3 (x=0.25) a metal to semiconductor transition was predicted in the literature [2]. In this contribution, however, we provide for the first time a systematic study of the electronic and magnetic properties of mixed WO3 and ReO3 phases. [1] See for example: M. Figlarz, Chemica Scripta 28, 3, (1988) [2] A. W. Sleight, J. L. Gillson, Sol. St. Comm. 4, 601, (1966) [3] O. Bock, U. Müller, Z. Anorg. Allg. Chem. 628, 987, (2000)

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