Synthesis, characterization and theoretical investigation of a new chalcohalide, Ba4GaS4F3

Abstract

A new fluorine-containing chalcohalide, Ba₄GaS₄F₃, has been synthesized by conventional high-temperature solid-state reaction. The compound crystallizes in the centrosymmetric space group I4₁/a with a = b = 16.628 (5) Å, c = 17.139 (10) Å, Z = 16. Experimental and theoretical results confirm that Ba₄GaS₄F₃ is a direct band gap compound with an experimental band gap of about 3.13 eV, and the band gap is mainly determined by the Ba-5p, F-2p and S-3p orbitals. What's more, different from the many newly discovered chalcohalides in the Ba₃AM₄Q (A = Ga, In; M = S, Se; Q = Cl, Br, I) family, Ba₄GaS₄F₃ is the first reported compound in the Ba₄AM₄D₃ (A = Ga, In; M = chalcogen; D = halogen) family. The results enrich the structural diversity of metal chalcohalides.