KBe2BO3F2 (KBBF) is the sole nonlinear optical (NLO) crystal that can practically generate deep-ultraviolet (UV) coherent light by a direct second-harmonic generation (SHG) process. However, the toxic BeO and crystal layer habit limit its application. With this background, a new beryllium-free borate, K5Mg2La3(BO3)6 (KMLBO), has been designed and synthesized through a high-temperature solution method. KMLBO crystallizes into the noncentrosymmetric space group P31m (No. 157) and features a three-dimensional framework structure consisting of alveolate [LaBO3]∞ layers further tightly bound via interlayer [BO3]3– groups. KMLBO not only exhibits desirable performances including deep-UV transparency, large SHG (∼3.1 × KH2PO4), and phase-matchability but also overcomes the crystal layer habit of KBBF, demonstrating that it is a potential deep-UV NLO crystal.
Qiang Wang,Wen Song,Yang Lan,Liling Cao,Ling Huang,Daojiang Gao,Jian Bi,Guohong Zou
KBe2BO3F2 (KBBF) with a perfect honeycomb hexagonal layered structure is the sole practical deep-ultraviolet (DUV) nonlinear optical material which could generate DUV coherent light through direct frequency doubling. However, the layered growth habit and the toxicity of Be severely hinder its extensive applications. Herein, a non-centrosymmetric fluoride carbonate, KLi2CO3F, was successfully developed via chemical co-substitution with KBBF as the prototype. KLi2CO3F preserves the structural merits of KBBF, containing neatly arranged infinite planar [Li2CO3F2]∞ layers. In particular, compared with the weak interlayer K–F electrostatic attraction in KBBF, KLi2CO3F presents a stronger interlayer binding energy induced by the shorter and stronger Li–F bonds, which effectively overcomes the layered tendency of crystal growth. Simultaneously, KLi2CO3F exhibits a large birefringence of approximately 0.102@546 nm and a short ultraviolet absorption edge down to 190 nm, indicating that it is a promising DUV birefringent material.
危险品化学品经营许可证（带存储）