RbSbSO4Cl2: an excellent sulfate nonlinear optical material generated due to the synergistic effect of three asymmetric chromophores

Sulfates have been overlooked as nonlinear optical materials in the past few decades. Herein, a new sulfate nonlinear optical material, RbSbSO4Cl2, was prepared via a facile hydrothermal synthetic route. The title compound crystallizes in the polar non-centrosymmetric (NCS) space group P2(1)2(1)2(1) and exhibits an intricate three-dimensional network constructed by interconnecting RbO5Cl4, SbO3Cl2 distorted polyhedra and a SO4 tetrahedron. The powder second-harmonic generation (SHG) measurements display that RbSbSO4Cl2 exhibits a strong SHG response of about 2.7 times that of KH2PO4 (KDP) and is type I phase-matchable. Theoretical calculation analysis confirmed that the large SHG effect originated from the synergistic effect of three coexisting NCS chromophores: Sb3+ with SCALP effect, highly polarizable Rb+ cations and a SO4 distorted tetrahedron.