Effect of the cation-to-silicon ratio on structural transformation and optical performance in [NaSr3Cl3][SiS4] and [NaSr4SCl][Si3S9]

Abstract

Two novel salt-inclusion chalcogenides, [NaSr₃Cl₃][SiS₄] and [NaSr₄SCl][Si₃S₉], were synthesized. The structural transition from centrosymmetric [NaSr₃Cl₃][SiS₄] (P2₁/m) to non-centrosymmetric [NaSr₄SCl][Si₃S₉] (P6₃) was investigated, and a performance comparison was conducted. [NaSr₄SCl][Si₃S₉] exhibits a wide band gap of 4.43 eV and a moderate second-harmonic generation response of ∼0.8 × AgGaS₂ at 2090 nm.