The discovery of new nonlinear optical (NLO) materials for IR light sources generation is essential for the development of critical technologies on tunable lasers, including laser guidance and telecommunications areas, etc. As for diamond-like semiconductors (DLSs), their inherently noncentrosymmetric (NCS) structures can be exploited in the pursuit of excellent properties and satisfy the prerequisites for frequency conversion application.
Current benchmark IR NLO materials including the chalcopyrite-type AgGaS2, AgGaSe2, and ZnGeP2 are the members of DLSs. Therefore, the exploration of new IR NLO materials with optimal key performances (concurrently large NLO coefficient and impressive laser damage threshold (LDT) has become imperative.
A research team led by Prof. PAN Shilie at the Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences chose the d10 elements-containing metal sulfides as research system and synthesized a new mercury-based quaternary DLS, Li4HgGe2S7 via solid-state reaction in vacuum-sealed silica tubes. This study was published as back cover in Chem. Commun.
Single-crystal X-ray diffraction (XRD) analysis shows that Li4HgGe2S7 crystallizes in the monoclinic Cc space group. Based on the analysis of its structure, researchers found that Li4HgGe2S7 could be viewed as the first example of exhibiting the unusual 10−membered LiS4 rings for known quaternary DLSs.
Overall properties investigations show that Li4HgGe2S7 satisfies the essential requirements as excellent IR NLO material and achieves a delicate balance of concurrently large NLO coefficient and impressive LDT, which are comparable to those of famous IR NLO materials (HgGa2S4 and BaGa4Se7). Moreover, theoretical calculation results verify well with the experimental values and reveal the origin mechanism of the second harmonic generation (SHG) effect.
The study provided a good way to design new promising IR NLO materials in the research system of d10 elements-containing DLSs. It was supported by the Western Light Foundation of CAS and the National Natural Science Foundation of China.
Figure:The Magazine Back Cover(Image by XTIPC)
Xinjiang Technical Institute of Physics & Chemistry,CAS