The Influence of Europium Impurity on the Recombination Luminescence in Y₂O₃

In this work the researched results of the spectral characteristics of the luminescence and the thermostimulated luminescence curves of Y₂O₃ and Y₂O₃:Eu ceramic materials at the X-ray excitation in the 85-295 K range were generalized. Considering the features of Y₂O₃ crystal structure and the possibility of the formation of the short-lived and stable hole and electron centers of V- and F-type by the ionizing radiation X-ray luminescence spectrum of ceramics at 85 K is fitted into the elementary Gaussian shape bands with the maxima near 3.40, 3.06, 2.67, 2.33, 2.09, and 1.91 eV. The main 3.40 and 3.06 eV bands of the luminescence are caused by the self-trapped excitons of (YO₆)⁹¯ complex, when the cation is localized in the field of the trigonal (C_{3i}) and monoclinic (C₂) symmetries. The emission at 2.67 eV and the weak bands in the 1.65-2.61 eV region are considered as the radiation of excitons localized on the anion vacancies and the electron centers of F-type (F⁺, F and F¯). The thermoluminescence of Y₂O₃ in the 186 and 204 K main peaks range is connected with the thermal destruction of the self-trapped states of O¯ ions that located in the field of the trigonal and monoclinic symmetries. The activator bands caused by ⁵D→ ⁷F_{j} electronic transitions in Eu³⁺ are only observed in the X-ray and thermostimulated luminescence spectra of Y₂O₃:Eu ceramics. It was assumed that both at the X-rays irradiation and an optical excitation in the band of the charge transfer of Y₂O₃:Eu sample the energy goes to Eu³⁺ through (Eu²⁺O¯) complexes (states) of the charge transfer.