Synthesis, crystal structure, and optical properties of the noncentrosymmetric sulfide Ce8Sb2S15

The new polar sulfide Ce8Sb2S15 contains discrete [SbS3]3- trigonal pyramids, which are packed in a noncentrosymmetric pseudolayer motif perpendicular to the c direction. The optical gap of Ce8Sb2S15 is about 1.99 eV, which originate from a symmetry and spin-allowed, intra-site Ce-4 f to Ce-5d electronic transition. Moreover, a weak SHG response was detected in the IR region.347