K2CdGe3S8: A New Infrared Nonlinear Optical Sulfide

A quaternary metal chalcogenide, namely K2CdGe3S8 (I), is obtained through a high-temperature solid-state approach. Compound I crystallizes with the non-centrosymmetric space group P2(1)2(1)2(1). It features a 2D layer structure with [CdGe3S8] layers consisting of tetrahedral GeS4 and CdS4 units, and counter K+ embedded between the layers. The compound exhibits a powder second-harmonic generation (SHG) response of similar to 0.1 times that of KH2PO4 (KDP) with phase-matchable character at the laser wavelength of 1064 nm. Remarkably, it has a wide band gap (3.20 eV), which corresponds to a favorable high laser-induced damage threshold of 6.7 times that of AgGaS2. In addition, the calculated birefringence (Delta n) is 0.039 at the wavelength of 1064 nm, which satisfies the Delta n criteria for a promising infrared NLO material.

Automated summary

A quaternary metal chalcogenide, K2CdGe3S8 (I), was synthesized through high-temperature solid-state approach. Compound I possesses a 2D layer structure with tetrahedral GeS4 and CdS4 units forming [CdGe3S8] layers, with K+ ions embedded in between. It shows a powder second-harmonic generation (SHG) response similar to 0.1 times that of KH2PO4 (KDP) at the laser wavelength of 1064 nm, indicating phase-matchable character. It has a wide band gap (3.20 eV), corresponding to a high laser-induced damage threshold 6.7 times that of AgGaS2, and a calculated birefringence (Delta n) of 0.039 at 1064 nm, meeting the criteria for a potential infrared NLO material.