Luminescence of europium(III) ions in a fluorinated yttrium-aluminum oxide matrix

GYLNQT

Abstract

The subject of many scientific works is oxides of yttrium and aluminum, as well as complex yttrium-aluminum oxide compositions. In many ways, the interest shown in them is determined by the need of modern optoelectronic technology for materials with improved optical, physicochemical and mechanical properties. In the vast majority of works, the attention of researchers is concentrated on individual oxide phases, as well as garnet and perovskite phases. Research on compositions of complex phase composition is limited, despite the potential for their use as compact luminescent sensors of electromagnetic radiation and in a number of other applications. We synthesized luminescent powders of complex phase composition based on yttrium and aluminum oxides at the atomic ratio Y³⁺ : Al³⁺ = 3 : 5 by thermal destruction of europium(III) activated gel systems prepared on the basis of ethyl acetate. The main components of the powders, depending on the composition of the initial mixtures and synthesis conditions, are oxides of yttrium, europium, complex oxides of yttrium and aluminum, as well as yttrium oxyfluorides of various compositions. Eu³⁺ ions form activator centers in the structure of oxide and oxyfluoride phases.  The luminescence of powders is associated with the return of 4f-electrons of Eu³⁺ ions from the metastable ⁵D₀ to the ground electronic state. Excitation of luminescence occurs as a result of the transition of electrons from the ground ⁷F₀ to excited electronic states, the transfer of energy from the vibrational motion of the oxoanion matrix to excited energy levels, and the transition of 2p-electrons of oxygen ions to vacant 4f-orbitals of Eu³⁺ ions. Changes in the multiplicity and intensity of bands and their individual components in the spectra are associated with the inclusion of fluorine atoms in the composition of europium activator centers and the influence of Al³⁺ ions on their symmetry in fluorinated yttrium-aluminum oxide phases. The distortion of the unit cell parameters confirms the deep interaction of phases, which affects the symmetry and luminescence of activator centers, which begin to form as a result of the strong coordination interaction of salts in the initial solution and further in the gel-like system based on ethyl acetate.