Two non-centrosymmetric scandium borate nonlinear optical crystals containing the B5O10 anion group

Abstract

The spontaneous crystallization approach was used to synthesize two non-centrosymmetric scandium borate crystal materials, K3ScB6O12 (1) and K6NaSrSc2B15O30 (2), possessing the [B5O10]5− group. Both compounds exhibit wide band gaps of 5.75 and 5.92 eV, respectively. The second harmonic generation (SHG) effects of 1 and 2 are 1.3 and 0.7 times that of the commercial material KH2PO4 (KDP), respectively. According to the Kurtz-Perry approach, 2 demonstrates type-I phase-matchable. First-principles calculations on 2 are done to better understand the link between structure and performance. The calculated results reveal that the discrete arrangement of [B5O10]5− groups and the distorted ScO6 polyhedra in the structure are mainly responsible for the SHG response of 2. Furthermore, since 1 and 2 possess short ultraviolet (UV) cut-off edges, they may be applicable as nonlinear optical (NLO) materials in the UV region.