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. LaCa2GeS4Cl3 crystallizes in the noncentrosymmetric hexagonal space group -P63mc (No. 186) with Z = 2, a = 9.731(1) Å, and c = 6.337(1) Å. Lanthanum and calcium are mixed on a pseudo-trigonal prismatic site, coordinated to three sulfur atoms on one triangular face and three chlorine atoms on the other. Isolated, slightly distorted tetrahedra of GeS4 are oriented with a tetrahedral 3-fold axis aligned along the crystallographic 3-fold rotation axis. Preliminary optical studies indicate that this material has a useful optical window extending approximately from 0.5 to 10 μm. Nonlinear optical activity of LaCa2GeS4Cl3 is demonstrated by the generation of green light when pumped with a 1.064 μm Nd:YAG laser