Structural interpretation of the infrared spectrum of a Sb0.05As0.45Se0.50 glassy semiconductor

The infrared (IR) absorption spectrum for glassy Sb0.05As0.45Se0.50 was measured in the wave number region 500-90 cm(-1) at room temperature and in a continuously purged sample compartment, following the polyethylene pellet method. Main structural units in the glassy are considered to be AsSe3 and SbSe3 pyramids, Se-8 rings and Se-n chains. By using X-ray diffraction data it was found a structural model with the assumption of tricoordinated As, tricoordinated Sb and dicoordinated Se [C. Corredor, J. Vazquez, R.A. Ligero, P. Villares, R. Jimenez-Garay, Materials Letters 36, 1998, 271; I. Quiroga, J. Vazquez,P. Villares, R. Jimenez-Garay, :Materials Letters 17, 1993, 333.] which confirms the information obtained by means of far-infrared transmission (I;IT). From the "Valence Force Field" (VFF) we can determine the vibrational frequencies, wi, of possible structural units of alloy in this study by using the expressions derived by Herzberg. The results for this alloy are the following: 85, 110 and 230 cm(-1), for AsSe3, and 112, 215 and 315 cm(-1), for SbSe3. The comparison between the frequencies obtained in the far-IR spectrum and the values calculated of the normal frequencies let us assign bands to structural units. (C) 2000 Elsevier Science B.V. All rights reserved.