High‐Performance Sulfate Optical Materials Exhibiting Giant Second Harmonic Generation and Large Birefringence
Xuehua Dong, Ling Huang, Hongmei Zeng, Zhien Lin, Kang Min Ok, Guohong Zou
Abstract
Abstract Discovering novel sulfate optical materials with strong second‐harmonic generation (SHG) and large birefringence is confronted by a great challenge attributed to the intrinsically weak polarizability and optical anisotropy of tetrahedral SO 4 groups. Herein, two superior‐performing sulfate optical materials, namely, noncentrosymmetric Hg 3 O 2 SO 4 and centrosymmetric CsHgClSO 4 ⋅ H 2 O, have been successfully synthesized through the introduction of a highly polarizable d 10 metal cation, Hg 2+ . The unique component layers in the reported compounds, [Hg 3 O 2 SO 4 ] ∞ layers in Hg 3 O 2 SO 4 and [HgClSO 4 (H 2 O)] layers in CsHgClSO 4 ⋅ H 2 O, induce enlarged birefringence in each sulfate. Remarkably, Hg 3 O 2 SO 4 exhibits a very large SHG response (14 times that of KH 2 PO 4 ), which is the strongest efficiency among all the reported nonlinear optical sulfates. Detailed theoretical calculations confirm that the employment of highly polarizable Hg 2+ is an effective strategy to design superior optical materials with large birefringence and strong SHG response.