Rational design of a promising oxychalcogenide infrared nonlinear optical crystal.

Oxychalcogenides with the performance-advantages of both chalcogenides and oxides are emerging materials class for infrared (IR) nonlinear optical (NLO) crystals that can expand the wavelength of solid-state lasers to IR regions and are of importance in industrial and civil applications. But rationally designing a high-performance oxychalcogenide NLO crystal remains a great challenge. Herein, we chose the melilite-type Sr 2 ZnSi 2 O 7 as the structure template. Through part isovalent substitution of S 2- for O 2- anions, the first hetero-anionic thiostannate Sr 2 ZnSn 2 OS 6 with wide IR transmission has been synthesized. More importantly, compared to the maternal oxide, Sr 2 ZnSi 2 O 7 , the second harmonic generation (SHG) response of Sr 2 ZnSn 2 OS 6 is enhanced by two orders of magnitude. In addition, Sr 2 ZnSn 2 OS 6 can exhibit a large band-gap and high laser damage threshold. These advantages make Sr 2 ZnSn 2 OS 6 a promising IR NLO crystal. Our research will provide insights into the rational design of new IR NLO crystals.