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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.

We have investigated the coprecipitation of tellurium(IV), tungsten(VI), and lanthanum(III) hydroxides through the addition of aqueous ammonia to a mixture of tellurium dioxide, lanthanum oxide, and tungstic acid solutions in hydrochloric acid. The effects of initial solution composition and precipitation pH on the composition of the precipitate have been assessed. It has been shown that the composition of the precipitate is essentially identical to that of the starting solution if the relative contents of lanthanum and tungsten in the mixture are within 20 mol % and precipitation is ceased at pH 7.

We have investigated the coprecipitation of tellurium(IV) and tungsten(VI) compounds through the addition of aqueous ammonia to a mixture of a tellurium dioxide solution in hydrochloric acid and tungstic acid. We have revealed general trends in the distribution of macrocomponents between the precipitate and solution and demonstrated the feasibility of proportional tellurium(IV) and tungsten(VI) precipitation in the pH range from 2 to 7.