Sol-Gel Synthesis of Fluorescent Materials Based on Tricalcium Aluminate

Abstract

Calcium aluminate Ca3Al2O6 and phosphors based on it were obtained by sol-gel method. Complex studies were used to identify the dynamics of phase and structural transformations in the synthesis of Ca3Al2O6. We used thermal analysis, IR spectroscopy, X-ray phase analysis, scanning electron microscopy and micro-X-ray spectral analysis. Solid-phase interaction in the formation of Ca3Al2O6 includes the steps of obtaining carbonate and calcium oxide at 700 °C, aluminates of composition Ca5Al6O14 (800 °C) and CaAl2O4 (900 °C). Ca3Al2O6 is formed at 850 °C, single-phase cubic calcium aluminate is formed at 1000 °C. The degree of formation of the particles is increased with increasing synthesis temperature. Using the method of adsorption of Gammet indicators we determined that the base Brensted centers predominate on the surface of calcium aluminate. The number of these centers decreases with an increase in the annealing temperature and with the introduction of the activator. The luminescent properties of the phosphors of the composition Ca3-xEuxAl2O6 (x = 0.01–0.1) were investigated by the method of spectrofluorimetry. The highest intensity of luminescence was achieved at x = 0.05. With a further increase in the content of europium, there was a concentration quenching of the luminescence.