Structural characterization and optical absorption spectrum of Cu3In5Te9 ordered defect semiconducting compound

The crystal structure of the ordered defect compound Cu3In5Te9, which has recently emerged as an excellent candidate for thermoelectric applications, was refined by the Rietveld method using X-ray powder diffraction data. It was established that this material crystallizes in the tetragonal ordered defect chalcopyrite or thiogallate structure with space group I (4) over bar (No. 82). From the analysis of the optical absorption spectrum near the fundamental absorption edge it was also found that the energy gap is direct allowed and the band gap energy is about 0.952 eV at room temperature.