A new non-centrosymmetric (NCS) polar sulfide PbGa2GeS6 has been synthesized by a self-fluxing method at a relatively low temperature of 550 °C with desirable properties for nonlinear optical (NLO) applications. Its structure is built by three types of infinite chains intersecting in three dimensions, where the NCS building units are tetragonal pyramids of PbS4 and tetrahedra of MS4 (M = Ga, Ga/Ge). Powder of PbGa2GeS6 exhibits phase-matchable (PM) second-order NLO activity with strong second harmonic generation (SHG) intensity of 0.5× AgGaS2 at the particle size of 150–210 μm, high laser-induced damage threshold (LIDT) of 5× AgGaS2, and a wide transmission range in infrared (IR) region (0.47–23 μm). First-principles calculations suggest that the macroscopic SHG response is originated from the cooperation of the lone pairs on Pb2+ and MS4 (M = Ga, Ga/Ge) tetrahedra. Considering its strong PM SHG response, high LIDT, wide IR transmission range, and relatively low synthesis temperature, PbGa2GeS6 should be a promising candidate for high-power IR NLO applications.

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Traditional infrared (IR) nonlinear optical (NLO) materials such as AgGaS 2 are crucial to key devices for solid-state lasers, however, low laser damage thresholds intrinsically hinder their practical application. Here, a robust strategy is proposed for unbiased highthroughput screening of more than 140 000 materials to explore novel IR NLO materials with high thermal conductivity and wide band gap which are crucial to intrinsic laser damage threshold. Via our strategy, 106 compounds with desired band gaps, NLO coefficients and thermal conductivity are screened out, including 8 nitrides, 68 chalcogenides, in which Sr 2 SnS 4 is synthesized to verify the reliability of our process. Remarkably, thermal conductivity of nitrides is much higher than that of chalcogenides, e.g., 5 × AgGaS 2 (5.13 W/m K) for ZrZnN 2 , indicating that nitrides could be a longneglected system for IR NLO materials. This strategy provides a powerful tool for searching NLO compounds with high thermal conductivity.