Spectroscopic study of some new cobalt-doped tellurite glass-ceramics

摘要

New glass-ceramics of the xCo(2)O(3)(100 - x)80TeO(2)-19Li(2)O-1ZrO(2) system (where 0 <= x <= 20 mol) were prepared by melt-quenching technique and investigated by X-ray diffraction, FTIR, UV-Vis and EPR spectroscopies. The nature of the samples and the structural changes that take place with increasing the cobalt oxide content were followed by X-ray diffraction. FTIR spectroscopy shows that the network structure of the studied samples consists of TeO3, TeO4, LiO4, CoO6 and ZrO4 structural units and the proportion between these units depends on the cobalt content of samples. UV-Vis measurements performed in the 300-1800 nm spectral range show absorption peaks characteristics of transitions belonging to both Co2+ and Co3+ ions. Based on the UV-Vis data, the optical band gap energy, refractive index, dielectric constant and tendency of metallization of the studied system were determined. The compositional evolution of these parameters was discussed with respect to the cobalt ions content of samples. The EPR spectra show the presence of Co2+ ions in both their high- and low-spin states, S = 3/2 and S = 1/2.