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

• Published in: Journal of materials science 2020-08, Vol.55 (23), p.9962-9971
• Main Authors: Bolunduţ, Liviu, Păşcuţă, Petru, Culea, Eugen, Boşca, Maria, Pop, Lidia, Ştefan, Răzvan
• Format: Article
• Language: English
• Subjects: Ceramic materials; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Cobalt; Cobalt oxides; Crystallography and Scattering Methods; Diffraction; Energy gap; Fourier transforms; Glass ceramics; Infrared spectroscopy; Materials Science; Metallizing; Polymer Sciences; Refractivity; Solid Mechanics; Spectrum analysis; Tellurium dioxide; X-ray diffraction; X-rays
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-020-04749-6

New glass–ceramics of the x Co 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 TeO 3 , TeO 4 , LiO 4 , CoO 6 and ZrO 4 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 Co 2+ and Co 3+ 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 Co 2+ ions in both their high- and low-spin states, S  = 3/2 and S  = 1/2.