Study of thermogenic color shift of high-temperature material of aluminium titanate

We studied the peculiarities of the color change of heat-resistant material based on aluminum titanate obtained by high temperature heat treatment and quenching in liquid nitrogen equimolar mixtures jointly precipitated hydroxides of aluminium and titanium or mechanical grinding of the respective oxides. The composition of the original mixture of oxides of aluminum and titanium was controled by chemical analysis. The phase composition of the synthesized samples was determined by x-ray powder diffraction. Quantitative determination of Ti3+ ions in the titanate aluminium and kinetic parameters of oxidation-restoration were performed by the EPR method. In the aluminum titanate obtained by quenching in liquid nitrogen annealed at 1550-1300 °C of equimolar mixture Al2O3 and TiO2, titanium ions are partially restored to the trivalent paramagnetic state, stabilized by the nearest oxygen vacancies, with concentration no more than 0.1% of the total content of titanium. When the firing temperature is in the range 1550-1450 °C oxides of aluminum and titanium are fully transformered in pseudobrookite titanate aluminum, and the activation energy of its partial dissociation with occurrence of Ti3+ is 4.9 ± 0.4 eV. The presence of small amounts of Ti3+ in the lattice of tempered aluminum titanate results grey-violet, bluish color. The color centers remain stable in the atmosphere up to 1100 °C, the process of oxidation of titanium is characterized by activation energy of 1.1 ± 0.3 eV.