Infrared and Raman studies on Snx–Sb5–Se95−x chalcogenide glasses

Tin–antimony–selenium (Sn–Sb–Se)-based systems belong to the ternary chalcogenide compounds of IV–V–VI group. They have potential applications in infrared region due to their heavy elemental masses, continuous variation of band gap-energies and lattice constants as well as electrical properties, with compositions. Structures of melt quench-synthesized samples of Snx–Sb5–Se95−x system, where x = 0, 5, 10 and 12.5-mole% have been studied using Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. FTIR spectra illustrates that addition of Sn-mole% to the system causes a shift in IR-peak’s intensity and width from long to the short wavelength. This change implies the breaking of Se chains that appeared around 210–254 cm−1 and the occurrence of pyramidal SbSe3 around 147–210 cm−1 and asymmetrical tetrahedral SnSe4 mode around 117–145 cm−1 for Sn = 5 mole% up to 180 cm−1 in Sn = 12.5 mole% spectra. Raman spectra show that a pyramidal SbSe3 peak is cited at 190-cm−1. The intensity of this peak is shifted towards −183 cm−1 when Sn-mole% is added to the system. The results confirm the validity of using 4, 3 and 2 as co-ordination numbers of Sn, Sb and Se, respectively, in the amorphous region, which is contained by the average co-ordination number, μ ⩽ 2.4 and the fraction of Sn–Se bonds, fSn–Se < 44.3%.