Pb5Ga6ZnS15: a noncentrosymmetric framework with chains of T2-supertetrahedra

Abstract

A novel noncentrosysmmetric sulfide, Pb₅Ga₆ZnS₁₅ (1), was synthesized for the first time. Its crystal structure revealed the presence of [GaS₂]⁻_∞ (chain 1, chains of [GaS₄]⁵⁻ tetrahedra) and [Ga₄S₉]⁶⁻_∞ (chain 2, chains of T2-supertetrahedra) connected by isolated [ZnS₄]⁶⁻ tetrahedra. Structure correlation with the network constructed solely using chain 1 (Pb₄Ga₄GeQ₁₂-type) is discussed. Pb₅Ga₆ZnS₁₅ was calculated to have a suitable static briefringence (Δn) of 0.1137, and a large nonlinear optical susceptibility d₃₁ of 58.32 pm V⁻¹ at a wavelength of 2.05 μm (0.6 eV), much higher than that of the benchmark AgGaS₂ (18.14 pm V⁻¹).