Synthesis and Photoluminescence of Fluorinated Yttria–Alumina Composites

Composites have been prepared via thermal decomposition of gel-like mixtures containing yttrium, aluminum, and europium(III) salts and ethyl acetate as a basic component. Luminescence of the composites is due to Eu3+ 5D0,1 → 7Fj electronic transitions. The luminescence is excited in intrinsic absorption bands of the Eu3+ ions and as a result of resonance vibrational energy transfer from the host to their excited state levels and transitions of O2– 2p electrons to the europium 4f orbital. The luminescence and luminescence excitation spectra demonstrate changes in the peak position of individual bands, redistribution of their intensity, and changes in their Stark structure. The observed changes are related to the different fractions of fluorine atoms in the composition of activator centers, their concentration, and the Y3+ : Al3+ atomic ratio in the synthesis products, obtained at a temperature of 800°C and synthesis times from 4 to 12 h and differing in phase composition and structure.