Ba5Zn4(BO3)6: A Nonlinear-Optical Material with Reinforced Interlayer Connections and Large Second-Harmonic-Generation Response.

A nonlinear-optical crystal Ba5Zn4(BO3)6 (BZBO) is obtained that is constructed with [Zn4(BO3)4O6]∞ units bridged by planar BO3 groups along the a axis based on the flexibility of the BO3 and ZnO4 groups. The distance between adjacent [Zn4(BO3)4O6]∞ layers in BZBO is 5.07 Å, which is much shorter than those of KBe2BO3F2, Ba2Zn(BO3)2, and Na2CsBe6B5O15. The smaller interlayer spacing and stronger bond between neighboring layers of BZBO contribute to a better growth habit than those of the other three. Also, with the cooperation of two kinds of nonlinear-optical active groups, BO3 and ZnO4, BZBO exhibits a large second-harmonic-generation response of about 2.6 times that of KDP.