Luminescence of Eu$^{3+}$ ions in a matrix of a fluorinated yttrium–aluminum composition

We studied the optical spectra of fluorinated yttrium–aluminum compositions activated by Eu$^{3+}$ ions. The compositions were synthesized by thermal decomposition at 800$^\circ$C of fluorine-containing complexes of yttrium, europium, and aluminum nitrate, isolated as sols from ethyl acetate (EA). The main phases of the compositions are (Y$_{1-x}$Eu$_{x}$)OF и (Y$_{1-x}$Eu$_{x}$)AlO$_{3}$. Photoluminescence is associated with $^{5}$D$_{1,2}$ $\to$ $^{7}$F$_{0,1,2}$ and $^{5}$D$_{0}$ $\to$ $^{7}$F$_{0,1,2,3,4}$ electronic transitions of 4$f$ electrons of Eu$^{3+}$ ions replacing yttrium ions in oxide and oxyfluoride. The dependences of luminescence on the composition and synthesis conditions of the compositions, the wavelength of the excitation radiation, and other factors are found.