K2CdGe3S8: A New Infrared Nonlinear Optical Sulfide

Abstract

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 P212121. 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 ~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 (Δn) is 0.039 at the wavelength of 1064 nm, which satisfies the Δn criteria for a promising infrared NLO material.

Alkali halide flux synthesis, crystal structure, and photoelectric response of quaternary thiosilicates K3Ga3Si7S20 and K2ZnSi3S8

“…The 2–1–3–8 system compounds have a similar two-dimensional layered structure, however, they crystallize in either a non-centrosymmetric ( e.g. , for K 2 CdGe 3 S 8 , K 2 ZnGe 3 S 8 , K 2 MnGe 3 S 8 ) 1,3,18,27,57 or a centrosymmetric ( e.g. , for α-K 2 ZnSn 3 S 8 , Rb 2 ZnSi 3 S 8 and Cs 2 ZnSi 3 S 8 ) 41,58 space group.…”