Synthesis and characterization of a new quaternary lanthanum oxythioantimonite: La6Sb4O12S3

A new lanthanum antimony chalcogenide compound has been synthesized by the combination of ZnO–Sb2S3–La2O3 at 1150 °C and characterized by single-crystal X-ray diffraction. The compound La6Sb4O12S3 crystallizes in the tetragonal space group I41/amd with <F>a=10.860(3)</F> Å, <F>c=15.316(5)</F> Å, and <F>Z=4</F>. The structure comprises a three-dimensional network of lanthanum oxysulfide polyhedra connected by antimony(III) oxide psi-tetrahedra. The structure forms around channels that are filled with a disordered sulfide anion that appears to be loosely held in the solid. Diffuse reflectance measurements showed that this compound has an optical band gap of 2.2 eV. Solid state Raman spectroscopy of this compound showed the vibrations expected for the [SbIIIO3]3- unit. According to thermal analysis data, this material decomposes at temperatures over 1050 °C. [Copyright &y& Elsevier]