LiNbTeO<sub>5</sub>: A High-Performance Multifunctional Crystal Material with a Very Large Second-Harmonic Generation Response and Piezoelectric Coefficient
Kaichuang Chen, Chensheng Lin, Guang Peng, Yu Chen, Haizhou Huang, Enze Chen, Yunxiao Min, Tao Yan, Min Luo, Ning Ye
Abstract
It is an urgent and challenging task to explore mid-infrared (mid-IR) nonlinear optical (NLO) crystals with excellent comprehensive performances. Herein, the first alkaline-metal niobium tellurite crystal LiNbTeO5 with outstanding mid-IR NLO and piezoelectric properties was synthesized by simple 1:1 fusion of LiNbO3 and TeO2. Its structure featured two types of second-order Jahn–Teller distortive units, namely, octahedral-coordination NbO6 and (TeO3)2– groups with stereoactive lone pairs as well as a rare LiO5 polyhedron. Its second-harmonic generation (SHG) effect was extremely strong (17 × KDP at 1064 nm and 2.3 × KTP at 2.09 μm), with one of the largest values among all reported Te-containing metal oxides. In addition, LiNbTeO5 exhibited other advantages over LiNbO3, including the widest IR transparent window (0.33–9.0 μm) among all reported Te-containing metal oxide NLO crystals, a higher laser damage threshold (LDT, 460 MW·cm–2), and a larger piezoelectric coefficient (d33 = 18 pC·N–1). Benefiting from its good growth habit and physicochemical properties, centimeter-sized crystals and high-quality devices were obtained. This work provided a promising NLO and piezoelectric multifunctional crystal, and the simple yet effective strategy was inspirational.