BaYOBO3: A deep-ultraviolet rare-earth oxy-borate with a large second harmonic generation response

Deep-ultraviolet (UV) nonlinear optical (NLO) crystals with excellent performances are of great importance in laser science and technology. However, to design and synthesize an ideal deep-UV NLO material with a balance between second harmonic generation (SHG) response and UV cut-off edge is still a huge challenge. Herein, a new oxy-borate BaYOBO3 (BaYBO) was designed and synthesized by substituting Be2+ with Y3+ from Sr2Be2B2O7. The BaYBO features a stable three-dimensional framework and satisfies the property balance between a large SHG response (~2.6×KH2PO4 (KDP)) and a short UV cut-off edge (<190 nm) as a promising deep-UV NLO candidate. The study of structure-property relationship indicates that the large SHG response of BaYBO is mainly attributed to the coplanar arrangement and large number density of BO3 triangles. These results demonstrate that substituting Be2+ with Y3+ cations is also a feasible strategy for developing new deep-UV NLO crystals.