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

Novel SHG effective inorganic open-framework chalcohalides, Ba(3)AGa(5)Se(10)Cl(2) (A = Cs, Rb and K), have been synthesized by high temperature solid state reactions. These compounds crystallize in the tetragonal space group I (4) over bar (No.82) with a = b = 8.7348(6) - 8.6341(7) angstrom, c = 15.697(3) - 15.644(2) angstrom, V = 1197.6(3) - 466.2(2) angstrom(3) on going from Cs to K. The polar framework of (3)infinity[Ga5Se10](5-) is constructed by nonpolar GaSe45- tetrahedron (T1) and polar supertetrahedral cluster Ga4Se108- (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 mu m (about 100 times that of the benchmark AgGaS2 in the particle size of 30-46 mu m) 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.