Sol-gel synthesis of composite powders in the TiO2-TeO2-SeO2 system

The aim of this paper is to study the gel formation tendency in the TiO2-TeO2-SeO2 system. Telluric acid (H6TeO6), selenous acid (H2SeO3) and titanium butoxide were used as precursors dissolved in ethylene glycol. Transparent monolithic and bright yellow colored gels are situated between 40-100 mol% TiO2, up to 20 mol% SeO2 and 65 mol% TeO2. The phase transformations of the as-prepared gels heat-treated up to 700 degrees C are investigated by XRD. The chemical states of C, Ti, Se and Te are characterized by means of XPS. Organic and OH groups participate in the amorphous organic-inorganic structure up to 250-300 degrees C. The structure of the inorganic amorphous phases above 300 degrees C consists of SeO3, TiO6 and TeOn structural units. The UV-Vis spectra of the binary and three-component gels exhibited a redshift of the cutoff in comparison with those of Ti butoxide gel due to the presence of selenium and tellurium units.