Analysis of the crystal structure of alloys of the [(Ge, Sn, Pb)(Te, Se)]m[(Bi, Sb)2(Te, Se)3]n (m, n = 0, 1, 2,...) family within the theory of closely packed spheres

Abstract

The processes of the formation of complex crystal structures–layered crystals of [(Ge, Sn, Pb)(Te, Se)]_m[(Bi, Sb)₂(Te,Se)₃]_n (m, n = 0, 1, 2,…) ternary alloys with different symmetries (space groups R\(\overline 3 \)m, P\(\overline 3 \)m₁, and P2₁/m)—are investigated within the theory of closely packed spheres (CPS theory). The structures of layered binary alloys of the Bi₂Te₃ (R\(\overline 3 \)m) and PbTe (F_m\(\overline 3 \)m and R3m) types are found to be related and formed based on the s3 triplet with cubic symmetry (Fm\(\overline 3 \)m), which is constructed by chalcogen (Se or Te) atoms.