Synthesis, structure, and third-harmonic generation measurements of a mixed alkali metal iodate, KLi2(IO3)3

Abstract

Pure polycrystalline samples and single crystals of a mixed alkali metal iodate, KLi2(IO3)3 were synthesized through standard solid state and hydrothermal reactions, respectively, by using Li2CO3, K2CO3, and I2O5 as reagents. Single-crystal X-ray diffraction analysis suggests that KLi2(IO3)3 exhibits a corrugated layered structure consisting of IO3 distorted trigonal pyramids, LiO4 tetrahedra, and K+ cations. Within the layer, both five-membered rings (5-MRs) and six-membered rings (6-MRs) exist. UV–vis diffuse reflectance spectral data suggest that KLi2(IO3)3 has a wide optical band gap of ca. 4.25 ​eV. Infrared spectrum of the title compound clearly confirms the existence of IO3 groups in the backbone. The framework of the iodate is thermally stable to ca. 450 ​°C. Third-harmonic generation measurements using 1500 ​nm radiation indicate that the third-order nonlinear optical susceptibility of KLi2(IO3)3 is ca. 3 times that of α-SiO2. The laser-induced damage threshold of KLi2(IO3)3 is comparable to that of α-SiO2. Calculated local dipole moment values of IO3 polyhedra are also reported to better understand the asymmetric coordination environment.