The effect of indium substitution on the structure and NLO properties of Ba6Cs2Ga10Se20Cl4

Abstract

The nonlinear optical (NLO) susceptibility and laser induced damage threshold (LIDT) of a material are two inversely correlated indicators of the NLO performance. Here two new NLO active indium substituted chalcohalides, Ba₆Cs₂In_xGa_10−xSe₂₀Cl₄ (x = 2, 1; x = 1, 2) possessing a T1–T2 supertetrahedron anionic framework structure, have been successfully synthesized by solid-state reactions. Unlike the transition metal, the indium substitutes gallium at both T1 and T2 sites according to a series of single crystal diffraction data. Property measurements on the polycrystalline samples reveal that such a substitution improves the crystallinity and LIDT without adversely affecting the SHG power if compared with the transition metal substitution. Consequently, the title compounds show an optimal NLO performance among the compounds of this type of structure obtained so far.

The collaboration between Fujian Institute of Research on the Structure of Matter (FJIRSM: Ling Chen) and Paul Scherrer Institute (PSI: Meitian Wang) started back in 1993 when they were master's degree students in the Chemistry Department, Beijing Normal University, and jointly worked on the project of rare earth metal iodides with low valence states focusing on solid-state syntheses, crystal structures and theoretical analyses (L. Chen, M. T. Wang, S. H. Wang, Synthesis and structure of new iodides Cs₄EuI₆ and Rb₄EuI₆, J. Alloys Comp. 1997, 256, 112–114.). Since then, the cooperation continued when they were scattered in Alberta University in Canada, and Iowa State University in USA. No matter where they were, their cooperation has never been interrupted. This work is their second joint publication.