To search for a new nonlinear optical (NLO) material to be used in the mid-IR region with excellent comprehensive performance including high laser damage threshold (LDT), K₂SbF₂Cl₃ has been synthesized by the hydrothermal method, and its potential as such a new material is evaluated for the first time. Its powder shows phase-matchable second harmonic generation (SHG) response of approximately 4 times as strong as that of KH₂PO₄ (KDP). Its optical band gap is 4.01 eV, which is much wider than the band gaps of the currently commercialised IR NLO crystals. This means that K₂SbF₂Cl₃ will exhibit a much higher LDT. Its powder also exhibits excellent transparency in the range of 0.31–14 μm and good thermal stability. The relationship between the composition, crystal structure and properties is discussed. These results indicate that K₂SbF₂Cl₃ is a promising candidate for IR NLO materials.

J. Mater. Chem. C, 2015