The direct observation of dislocations in bismuth telluride

Abstract

The Crystallography of Bismuth Telluride. Bismuth telluride has a rather complex rhombohedral crystal structure (1). The crystals are built up of layers of (111) orientation, each layer containing three planes of tellurium atoms and two of bismuth so arranged that at the boundary between layers two planes of tellurium atoms occur together. The projection of the structures on a (112) plane is shown in Fig. 1 a. The bonding in the layers is covalent, but that between adjacent tellurium layers is very weak. Therefore (111) cleavage occurs readily; furthermore (111) slip may be expected. The arrangement of atoms in the (111) planes is close-packed and the slip vector is b as shown in Fig. 1 b where I | b | =4.37 Å.