Rational Design of the Nonlinear Optical Response in a Tin Iodate Fluoride Sn(IO<sub>3</sub>)<sub>2</sub>F<sub>2</sub>
Min Luo, Fei Liang, Xia Hao, Donghong Lin, Bingxuan Li, Zheshuai Lin, Ning Ye
Abstract
A new tin iodate fluoride, Sn(IO3)2F2, was meticulously designed based on Sn(IO3)4 with an intriguing chemical tailoring transformation from the centrosymmetric to noncentrosymmetric structure. Sn(IO3)2F2 crystallizes in polar space group P21 and features an one-dimensional chain constructed by IO3 and SnO4F2. It has an enlarged band gap (4.08 eV) compared to the Sn(IO3)4 (3.96 eV) because of the introduction of strong electronegative F–. Also, powder second-harmonic generation (SHG) measurements revealed that Sn(IO3)2F2 is a phase-matchable nonlinear crystal with a strong SHG response about 3 times that of KH2PO4. Theoretical investigations elaborated that its large nonlinearity originates from the synergistic effect of lone pairs on IO3 and flexible dipole moments of SnO4F2 polyhedra.