Noncentrosymmetric Inorganic Open-Framework Chalcohalides with Strong Middle IR SHG and Red Emission: Ba3AGa5Se10Cl2 (A = Cs, Rb, K)

Abstract

Novel SHG effective inorganic open-framework chalcohalides, Ba₃AGa₅Se₁₀Cl₂ (A = Cs, Rb and K), have been synthesized by high temperature solid state reactions. These compounds crystallize in the tetragonal space group I4̅ (No.82) with a = b = 8.7348(6) – 8.6341(7) Å, c = 15.697(3) – 15.644(2) Å, V = 1197.6(3) – 1166.2(2) ų on going from Cs to K. The polar framework of ³_∞[Ga₅Se₁₀]^5– is constructed by nonpolar GaSe₄^5– tetrahedron (T1) and polar supertetrahedral cluster Ga₄Se₁₀^8– (T2) in a zinc-blende topological structure with Ba/A cations and Cl anions residing in the tunnels. Remarkably, Ba₃CsGa₅Se₁₀Cl₂ exhibits the strongest intensity at 2.05 μm (about 100 times that of the benchmark AgGaS₂ in the particle size of 30–46 μm) among chalcogenides, halides, and chalcohalides. Furthermore, these compounds are also the first open-framework compounds with red photoluminescent emissions. The Vienna ab initio theoretical studies analyze electronic structures and linear and nonlinear optical properties.