[GaF(H 2 O)][IO 3 F]: a promising NLO material obtained by anisotropic polycation substitution.

A novel salt-inclusion fluoroiodate [GaF(H ₂ O)][IO ₃ F] derived from CsIO ₂ F ₂ was ingeniously obtained through anisotropic polycation substitution. Because the catenulate [GaF(H ₂ O)] ²⁺ framework serves as a template for the favorable assembly of the polar [IO ₃ F] ^2- groups and contributes to the nonlinear coefficient, [GaF(H ₂ O)][IO ₃ F] exhibits a greatly improved second-harmonic generation (SHG) effect of 10 times that of KH ₂ PO ₄ (KDP) and a considerable band gap of 4.34 eV compared to the parent compound CsIO ₂ F ₂ (3 × KDP, 4.5 eV). Particularly, to the best of our knowledge, [GaF(H ₂ O)][IO ₃ F] has the largest laser-induced damage threshold (LDT) of 140 × AgGgS ₂ of the reported iodates. All these results signify that [GaF(H ₂ O)][IO ₃ F] 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.
Competing Interests: The authors declare no competing financial interest.
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