BONDING IN UNCONVENTIONAL SEMICONDUCTING CHALCOGENIDES .2. THEORETICAL INTERPRETATIONS FROM MOSSBAUER-SPECTROSCOPY, X-RAY ABSORPTION AND BAND-STRUCTURE CALCULATIONS

Theoretical interpretations from Mossbauer spectroscopy, X-ray absorption and band structure calculations have been performed in some unconventional semiconducting compounds Sb2S3, Sb2Se3, Sb2Te3, SbTeI, SbI3, TlSbS2 and Tl3SbS3. The XAS spectra at the L(I), L(III) edges of Sb and K edge of S have been analysed and compared with the partial densities of states (PDOS) of Sb and S in TlSbS2 and Tl3SbS3. The good agreement between the experimental data and the theoretical calculations has allowed the analysis of the 2p --> 5ssigma* transition peak at the SbL(III) edge. A systematic estimation of the area under this s structure has been carried out, A linear dependence between these measured areas and the corresponding Mossbauer Isomer Shift (MIS) is clearly demonstrated and shows the complementarity between XAS (for conduction bands) and Mossbauer spectroscopy (for valence band) to analyse the s(Sb) contribution to the electronic structure.