Pb3(SeO3)Br4: a new nonlinear optical material with enhanced SHG response designed via an ion-substitution strategy

Using an ion-substitution strategy, herein, a new polar material, Pb3(SeO3)Br4, with a greatly enhanced SHG response has been successfully designed and synthesized through a hydrothermal reaction. Pb3(SeO3)Br4 crystallizes in the NCS space group P212121 and consists of a three-dimensional framework formed by interconnecting one-dimensional chains, with a good thermal stability up to 230 °C. This compound exhibits a phase-matchable SHG response as strong as that of KH2PO4 (KDP) and a relatively wide mid-infrared (mid-IR) transparent window. Moreover, the optical band gap of Pb3(SeO3)Br4 reaches about 3.35 eV, thus leading to a high laser damage threshold (LDT) of 67 MW cm−2, which is over 12 times that of AgGaS2 (<5 MW cm−2) measured under the same condition. All these findings suggest that Pb3(SeO3)Br4 would be a candidate for an NLO material in the mid-IR region.