Synthesis, crystal structures, and electronic properties of one dimensional Ba9Sn3(Te1−xSex)15 (x = 0–1)

Abstract

In this work, the Ba₉Sn₃Te₁₅ compound has been synthesized for the first time under high pressure and high temperature conditions. Single-crystal X-ray diffraction analysis shows that Ba₉Sn₃Te₁₅ crystallizes into a hexagonal structure with a space group of Pc2 (188) and lattice parameters of a = b = 10.2403(1) Å, and c = 20.7720(2) Å. The crystal structure contains trimeric one-dimensional chains with face-sharing SnTe₆ octahedrons stacked along the c-axis. These chains are arranged in a triangular lattice in the ab plane. The energy dispersive X-ray spectroscopy measurement for a single crystal of Ba₉Sn₃Te₁₅ shows approximately 6% vacancies on the Sn sites. The anion Te can be substituted by Se to form Ba₉Sn₃(Te_1−xSe_x)₁₅ with x = 0–1. The resistivity and Seebeck coefficient measurements were performed. Ba₉Sn₃Te₁₅ behaves similar to a semiconductor with a band gap of approximately 24 meV. When Se is doped, the resistivity increases and the band gap is enhanced to 508 meV for x = 1. The Seebeck coefficient ranges from 31 μV K⁻¹ to 90.7 μV K⁻¹. Ab initio calculations were also performed to study the density of states and band structures for Ba₉Sn₃Te₁₅ and Ba₉Sn₃Se₁₅.