[GaF(H2O)][IO3F]: a promising NLO material obtained by anisotropic polycation substitution

Abstract

A novel salt-inclusion fluoroiodate [GaF(H₂O)][IO₃F] derived from CsIO₂F₂ was ingeniously obtained through anisotropic polycation substitution. Because the catenulate [GaF(H₂O)]²⁺ framework serves as a template for the favorable assembly of the polar [IO₃F]²⁻ groups and contributes to the nonlinear coefficient, [GaF(H₂O)][IO₃F] exhibits a greatly improved second-harmonic generation (SHG) effect of 10 times that of KH₂PO₄ (KDP) and a considerable band gap of 4.34 eV compared to the parent compound CsIO₂F₂ (3 × KDP, 4.5 eV). Particularly, to the best of our knowledge, [GaF(H₂O)][IO₃F] has the largest laser-induced damage threshold (LDT) of 140 × AgGgS₂ of the reported iodates. All these results signify that [GaF(H₂O)][IO₃F] is a promising nonlinear optical (NLO) crystal. This work also proposes that anisotropic polycation substitution is an effective approach to optimize the SHG effect and develop excellent NLO materials.