Local Structure and Defect Chemistry of [(SnSe)1.15]m(TaSe2) Ferecrystals - a New Type of Layered Intergrowth Compound

C. Grossea,b, R. Atkinsa, H. Kirmseb, A. Mogilatenkob,c, W. Neumanna,b, and D.C. Johnsona

Published in:

J. Alloys Compd., vol. 579, pp. 507-515 (2013).

© 2013 Elsevier B.V. All rights reserved. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the Elsevier B.V.

Abstract:

The atomic structure of the family of ferecrystals [(SnSe)1.15]m(TaSe2) (m = 1, 3, and 6) was investigated by means of transmission electron microscopy. The tantalum in the TaSe2 layers was observed to have trigonal prismatic coordination similar to that found in the 2H polytype of bulk TaSe2. The structure of the SnSe constituent was found to be similar to that of orthorhombic α-SnSe. In the compounds with m = 1 and m = 3, regions with a local ordering of the layers along a commensurate axis, similar to the ordering in conventional misfit layer compounds, were observed. However, on a longer range the ferecrystals were found to exhibit a turbostratically disordered structure. Stacking defects were occasionally found in the samples in which a layer is interrupted and the surrounding layers are bent around these defects, while maintaining abrupt interfaces instead of interdiffusing. Volume defects were found in one sample of [(SnSe)1.15]1(TaSe2)1 in which a SnSe layer locally substitutes a part of a TaSe2 layer without interrupting the surrounding layers.

a Department of Chemistry, University of Oregon, Eugene, OR 97401-3753, USA
b Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
c Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, 12489 Berlin, Germany

Keywords:

ferecrystals; misfit layer intergrowth compounds; atomic scale structure; turbostratic disorder; high-resolution transmission electron microscopy.