The new quaternary lanthanum copper oxysulfide La3CuO 2S3 has been synthesized by the reaction of La 2S3 and CuO at 1223K. This compound crystallizes in space group Pnma of the orthorhombic system with four formula units in a cell of dimensions at 153K of a=14.0318(7)Å, b=3.9342(2)Å, and c=12.5212(6)Å. The structure of La3CuO2S 3 consists of a three-dimensional framework of interconnected LaOnS8-n bicapped trigonal prisms and CuS4 tetrahedra. Optical absorption measurements on a La3CuO 2S3 single crystal led to derived band gaps of 2.01eV in both the  and  directions.
Bibliographical noteFunding Information:
This research was supported by NSF Grant DMR00-96676 (JAI) and a GlaxoSmithKline-sponsored ACS Division of Analytical Chemistry fellowship to CLH. Use was made of the MRL Central Facilities supported by the National Science Foundation at the Materials Research Center of Northwestern University under Grant No. DMR00-76097.