Glass-forming region and optical properties of the TeO2 - ZnO - NiO system

The glass-forming region of the ternary TeO2 - ZnO - NiO system has been determined using a conventional melt-quenching method under controlled condition. The stable samples containing up to 35 mol% NiO were prepared by the rapid cooling technique while a low cooling rate was allowed to obtain glasses containing 15 mol% NiO. The formation of tellurium, zinc and nickel complex oxides (e.g. NiTe2O5, Zn3Te2O8) crystalline phases in a powder batches during the glass synthesis at different temperatures were studied. Investigations of the crystallization processes in glasses showed the formation of the same complex oxides phases as in the batch. The basic thermal properties of ternary glasses were determined by DSC and an increase of glass temperature with increase in the concentration of NiO in the glass matrix was shown. The optical absorbance spectrum of the glasses exhibited three broad bands with four maxima located at about 430, 720, 810 and 1320 nm corresponding to the d-d transitions of Ni2 + ion in octahedral coordination. The ligand field, splitting and Racah parameters were calculated and its dependence on the concentration of NiO was established.