KY(BO): A Potential UV Nonlinear-Optical Crystal Designed by a Chemical Substitution Strategy.

Nonlinear-optical (NLO) crystals capable of controlling and manipulating light to generate coherent radiation at challenging wavelengths are of significant interest. However, designing a new UV NLO crystal remains difficult due to the rigid requirements for structure and properties. Herein, we have successfully designed and synthesized a novel noncentrosymmetric (NCS) rare-earth borate UV NLO crystal, KY(BO), through the heterovalence substitution of YAl(BO). KY(BO) (KYBO) crystallizes in the NCS and polar space group of 6, with the structure formed by the interconnectioned BO triangles and YO polyhedra through corner-sharing and edge-sharing. The property measurements indicate that KYBO is second-harmonic-generation-active with a moderate response, ∼2 × KDP. Meanwhile, KYBO can exhibit a short UV cutoff edge (λ < 190 nm), indicating its potential as a new UV or deep-UV NLO crystal.