Shedding Light on the Structure and Characterization of K<sub>2</sub>ZnGe<sub>2</sub>O<sub>6</sub>: A Phase-Matchable Nonlinear Optical Crystal
Jinmiao Jiao, Fei Liang, Conggang Li, Tao Han, Wenli Zhao, Yuheng She, Ning Ye, Zhanggui Hu, Yicheng Wu
Abstract
Nonlinear optical (NLO) materials have recently aroused great interest owing to their capability of frequency conversion in solid-state lasers. Herein, we report an acentric zinc germanate K2ZnGe2O6 obtained successfully through spontaneous crystallization methods. It affords a novel three-dimensional (3D) framework comprised of [GeO4] and [ZnO4] motifs with K atoms located in the tunnels. K2ZnGe2O6 displays a moderate second-harmonic-generation (SHG) intensity (0.73 × KDP) with phase-matchable behavior. Optical characterization demonstrated that it has a UV cutoff edge located at 368 nm with a large energy band of 3.23 eV, accompanied by a wide transmission window, covering a 3–5 μm atmospheric window. Moreover, thermal properties implied that it possesses intriguing thermal stability of 987 °C and a congruent melting nature. Additionally, first-principles calculations unveiled that the NLO performance was primarily attributed to the collective effect of [GeO4] and [ZnO4] building units. These findings indicate that K2ZnGe2O6 is a potential NLO crystal.