Second-Order Nonlinear-Optical-Active Selenide Borate YSeBO₂: Featuring a [YSeBO₂] Planar Belt

Chalcogenide borates were very rarely investigated in the past. As the second selenide borate, YSeBO₂ obtained by a high-temperature solid-state reaction crystallizes in the noncentrosymmetric orthorhombic space group Cmc2₁ with a novel structure type. Its structure consists of two basic building units, [BO₃]^3- planar triangles and [YO₃Se₄]^11- pentagonal bipyramids, and features the [YSeBO₂] planar belt. Second-harmonic-generation measurement shows its phase-matchable activity. YSeBO₂ has an optical energy gap of 3.45 eV. Density functional theory calculation is also performed, addressing the electronic structure and nonlinear-optical property.