K₃Y₃(BO₃)₄: 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, K₃Y₃(BO₃)₄, through the heterovalence substitution of YAl₃(BO₃)₄. K₃Y₃(BO₃)₄ (KYBO) crystallizes in the NCS and polar space group of P6₃mc, with the structure formed by the interconnectioned BO₃ triangles and YO₈ 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_cutoff < 190 nm), indicating its potential as a new UV or deep-UV NLO crystal.