SYNTHESIS AND STRUCTURE OF A NEW QUINARY SULFIDE HALIDE - LACA2GES4CL3

A new quinary rare earth sulfide-halide compound has been synthesized and its structure determined by single crystal X-ray diffraction. LaCa 2GeS4Cl3 crystallizes in the noncentrosymmetric hexagonal space group C-6 upsilon(4)-P6(3)mc (No. 186) with Z = 2, a = 9.731(1) Angstrom, an d c = 6.337(1) Angstrom. Lanthanum and calcium are mixed on a pseudo-t rigonal prismatic site, coordinated to three sulfur atoms on one trian gular face and three chlorine atoms on the other. Isolated, slightly d istorted tetrahedra of GeS4 are oriented with a tetrahedral 3-fold axi s aligned along the crystallographic 3-fold rotation axis. Preliminary optical studies indicate that this material has a useful optical wind ow extending approximately from 0.5 to 10 mu m. Nonlinear optical acti vity of LaCa2GeS4Cl3 is demonstrated by the generation of green light when pumped with a 1.064 mu m Nd:YAG laser.