Effect of 130 keV pulsed electron irradiation on the efficiency of radiative transitions in Eu-doped glass-ceramics CaSiO₃

Polycrystalline glass-ceramic CaSiO₃ doped with Eu³⁺ ions was obtained by devitrification. The analysis of the photoluminescent characteristics of the obtained glass-ceramic is carried out. It was found that as a result of the devitrification of CaSiO₃, two phases are formed, identified as pseudowollastonite (β-CaSiO₃) as the dominant phase together with a small percentage of tridymite (SiO₂). The UV–Vis optical absorption of Eu^3+-doped CaSiO₃ was performed using a UV–Vis spectrophotometer. The main objective of this work was to study the effect of the pulsed corpuscular action of electrons accelerated in a field of 130 keV on energy transitions in the Eu³⁺ ion. It is found that, upon steady-state excitation of the photoluminescent signal in the PLE spectra of unirradiated samples at wavelengths below 300 nm, two broad excitation peaks are displayed, possibly associated with O − Eu and O − Si CT transitions. Above 300 nm the characteristic excitation band from ⁷F₀ ground state to ⁵H_j, ⁵D₄, ⁵G_j, ⁵L₆, ⁵D₃, and ⁵D₂ states of the Eu³⁺ ions are shown. It was found that, as a result of exposure to an electron beam in the photoluminescence spectra of europium, a redistribution of the relative intensities of the ⁵D₀ → ⁷F₂ and ⁵D₀ → ⁷F₁ transitions occurs. The calculation of the asymmetry ratio of these transitions showed values for an unirradiated sample R₂₁ = 2.06 and irradiated R₂₁ = 2.52, which indicates a decrease in the symmetry of the crystal field around Eu³⁺ ions after irradiation. Several reasons for the decrease in the relative intensity of the Eu³⁺ luminescence signal after electron irradiation, caused by the effect of electrization of the material, intrinsic defects of the matrix, and inhomogeneous phase composition, are discussed.