Combined experimental and theoretical investigations of Ba3GaS4I: interesting structure transformation originated from the halogen substitution
Inorganic chalcohalides have emerged as promising functional materials for a range of applications. However, most of them are chlorides and bromides, while iodides are still rare. Herein, a new quaternary iodine-based chalcohalide Ba3GaS4I has been acquired by reaction of BaS, Ga, S and BaI2 at 1173 K. The single-crystal XRD analysis reveals that Ba3GaS4I belongs to a centrosymmetric structure (orthorhombic, space group Cmcm, a = 6.991(3) Å, b = 15.910(7) Å, c = 9.698(4) Å, V = 1078.6(7) Å3, and Z = 4) and consists of isolated [GaS4] tetrahedra with charge-balanced Ba2+ cations and I– anions. Ba3GaS4I can be regarded as the product of chemical substitution of Ba3GaS4X (X = Cl, Br), which adopt a different space group, Pnma. The influences of the halogen elements on the band-gap and birefringence have been discussed through first principle calculations and structure comparison.