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

Abstract

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 P2₁2₁2₁ 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.