Interdiffusion of Bi and Sb in Superlattices Built from Blocks of Bi 2 Te 3 , Sb 2 Te 3 and TiTe 2

The reaction kinetics of [(Ti-Te)]x[(Sb-Te)]y, [(Bi-Te)]x[(Sb-Te)]y, [(Ti-Te)]w[(Bi-Te)]x and [(Ti-Te)]w[(Bi-Te)]x[(Ti-Te)]y[(Sb-Te)]z precursors as a function of annealing temperature and time was probed using x-ray diffraction techniques to define the parameters required to form superlattice structures. [(TiTe2)1.36]x[Sb2Te3]y and [(TiTe2)1.36]x[Bi2Te3]y superlattices were observed to form while [(Bi-Te)]x[(Sb-Te)]y precursors yielded only Bi2−xSbxTe3 alloys. This behavior was correlated with the miscibility/immiscibility of the constituents of the targeted superlattices. For the three component system, Bi and Sb were observed to interdiffuse through the Ti-Te layer over the range of Ti-Te thicknesses explored, resulting in formation of (BixSb1−x)2Te3 alloys within the superlattice structure. When the Bi2Te3 and Sb2Te3 thicknesses were equal, symmetric [{(TiTe2)}1.36]w[(Bi0.5Sb0.5)2Te3]y superlattices were formed.