Growth, Properties, and Theoretical Analysis of KBa2(PO3)5 Single Crystal

In this study, we used a high-temperature solution to grow KBa2(PO3)5 (KBP), which is a potential deep-ultraviolet (UV) nonlinear optical crystal. It is a congruent melting compound that solidifies in a non-centrosymmetric crystal system that is monoclinic with the Pc space group. KBP exhibits a powder second-harmonic response at 1064 nm incident radiation, with an efficiency of 0.9 × KDP. KBP exhibits a wide transparency range, as the cutoff absorption edge in the UV region is as short as 167 nm. In addition, we performed Raman and IR spectroscopies on the reported material, which confirmed the existence of 1D [PO3]∞ chains in KBP. We also performed first-principles calculations to elucidate that KBP's nonlinear optical activity stemmed from the 1D [PO3]∞ chains, and that the optical properties stemmed from the P–O groups.