Interfacial defect structure at Sb2Te3 precipitates in the thermoelectric compound AgSbTe2

We analyze a line defect at the interface between tetradymite-structured Sb2Te3 and rocksalt-structured AgSbTe2 using high-resolution electron microscopy. By determining the step-height and Burgers vector of this defect, we show how motion of the defect, through a diffusive glide mechanism, can transform material from the rocksalt structure to the tetradymite structure. We discuss the atomic flux requirements for this defect motion. This analysis helps to explain the growth mechanism of tetradymite precipitates within rocksalt-structured chalcogenides.