Interfacial disconnections at Sb_2Te_3 precipitates in PbTe: Mechanisms of strain accommodation and phase transformation at a tetradymite/rocksalt telluride interface

Abstract

Understanding the structure and formation mechanisms of interfaces between different telluride phases is important to the development of thermoelectric nanocomposites. Here, we investigate the interfacial structure of tetradymite precipitates in a rocksalt telluride matrix, focusing in particular on precipitates of Sb_2Te_3 in PbTe. Using high-resolution transmission electron microscopy, we investigate the structure and arrangement of interfacial disconnections—i.e. interfacial steps possessing dislocation character—observed in this system. Our analyses provide insight concerning the roles of these defects in accommodating the large interfacial misfit (6.7%) in this system and in mediating the transformation from the rocksalt to the tetradymite structure. Our observations also suggest how such interfacial disconnections could arise through the dissociation of crystal lattice dislocations that accommodate the misfit on initially flat segments of the interface.

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