Na4SnS4 and Na4SnSe4 exhibiting multifunctional physicochemical performances as potential infrared nonlinear optical crystals and sodium ion conductors

Abstract

In this study, Na₄SnS₄ and Na₄SnSe₄ compounds were successfully synthesized and their physicochemical performances were systematically investigated via experimental and theoretical methods. Research results show that they display excellent properties as potential infrared nonlinear optical (IR NLO) crystals and sodium ion conductors, including large NLO effects (0.7 vs. 1.8 × benchmark AgGaS₂), high laser-damage resistance (9.0 vs. 3.5 × AgGaS₂), moderate ion conductivities and small activation energies. Moreover, their structure–performance relationship was also studied via first principles calculations.