DOUBLE YTTRIUM THIOSILICATES AYSiS4 (A = Rb, Cs): SYNTHESIS, STRUCTURE, OPTICAL PROPERTIES

Abstract

Abstract: By the high-temperature synthesis new double yttrium thiosilicates AYSiS4, A = Rb, Cs are obtained. The compounds crystallize in the orthorhombic system (space group P212121) with the following parameters: a = 6.3381(4) Å, b = 6.5961(4) Å, c = 16.8868(12) Å for RbYSiS4 and a = 6.3303(4) Å, b = 6.6593(5) Å, c = 17.5795(13) Å for CsYSiS4. The compound with rubidium is rapidly hydrolyzed by water; the compound with cesium is stable in dry air. For CsYSiS4 the band gap estimated by diffuse reflectance is 3.8 eV. The photoluminescence spectrum has a broad band in the visible region with the maximum at λ = 492 nm (green region). The lifetimes are τ1 = 5.25 µs and τ2 = 0.26 µs with the quantum yield of <1%. [Figure not available: see fulltext.]