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.