K6Li3Sc2B15O30: A new nonlinear optical crystal with a short absorption edge

Abstract

A new non-centrosymmetric rare-earth borate K₆Li₃Sc₂B₁₅O₃₀ has been synthesized by solid-state reaction technique, and a transparent crystal with dimensions of 28 × 28 × 8 mm³ was successfully obtained with a K₂O–Li₂O–B₂O₃–LiF flux by the top-seeded solution growth method. Single crystal X-ray diffraction results show that it crystallizes in the space group R32 (No. 155). In the structure of K₆Li₃Sc₂B₁₅O₃₀, B₅O₁₀ groups are bridged by discrete ScO₆ octahedra, giving rise to columns packed side-by-side in a rhombic motif along the c-axis to form a three-dimensional framework with one-dimensional tunnels along the a- and b-axes. K₆Li₃Sc₂B₁₅O₃₀ is nonhygroscopic, and melts incongruently at 838 °C. The transmittance spectrum of K₆Li₃Sc₂B₁₅O₃₀ exhibits a short UV absorption edge at 190 nm. Second harmonic generation (SHG) tests on powder samples reveal that K₆Li₃Sc₂B₁₅O₃₀ possesses an SHG effect close to that of KDP.