Structural Modulation from Cu₃PS₄ to Cu₅Zn_0.5P₂S₈: Single-Site Aliovalent-Substitution-Driven...

Diamond-like (DL) chalcophosphates, which possess the merits of impressive second-harmonic-generation (SHG) responses, strong laser-induced damage thresholds, and low melting points, are highly desirable for IR nonlinear-optical (NLO) applications. Herein, a new quaternary DL chalcophosphate, Cu₅Zn_0.5P₂S₈, is successfully discovered, taking known Cu₃PS₄ as the template via a single-site aliovalent-substitution strategy. It crystallizes in the orthorhombic system with noncentrosymmetric space group Pmn2₁, and the 3D DL structure is built by corner-shared [(Cu/Zn)S₄], [CuS₄], and [PS₄] tetrahedra. Compared with its parent Cu₃PS₄, Cu₅Zn_0.5P₂S₈ exhibits a good phase-matching capability and a sharply enhanced SHG effect (10Cu₃PS₄) benefiting from partial Zn substitution. Moreover, the structure-performance relationships have been illustrated by means of theoretical investigations. Such an aliovalent-substitution strategy based on known DL semiconductors might be widely applied for the discovery of high-performance IR NLO crystals.