Luminescent properties of Tb and Eu activated AxB1-xAlO3 (A = Y, Lu, Gd; B = Lu; x = 0, 0.5, 1) mixed oxides crystals prepared by micro-pulling-down method

Abstract

Within this work the single crystals of terbium- and europium-activated AxB1-xAlO3 (A = Y, Lu, Gd; B = Lu; x = 0, 0.5, 1) mixed perovskites were grown from the melt by micro-pulling-down method. The Eu3+ and Tb3+ doping ions were chosen intentionally, as they can create in the perovskite host the trapping centers for electrons and holes, respectively. Luminescent properties of the obtained crystals have been analyzed by cathodo- (CL) and thermo- (TL) luminescence measurements. The temperature and wavelength resolved TL spectra have been measured after the samples irradiation with beta particles of 90Sr/90Y source. We have found that the shape of CL and TL spectra of the studied perovskite crystals is strongly affected by the local surrounding of dopant, depending on the size of cations and cations-ligands distances in the perovskite hosts. It was confirmed that Eu-activated mixed perovskite crystals practically do not show a measureable TL in the UV-VIS range. In turn, the measured CL spectra showed a quite strong luminescence of Eu3+ ions in the red range. The measurements performed for Tb-doped samples showed a significant TL in the UV-VIS spectral range with the most prominent emission peak below 200 °C. The measured TL spectra showed a typical luminescence of Tb3+ ions in the green range. For Y–Lu substituted crystals the maximum of TL emission was shifted towards higher temperatures what is probably correlated with the band gap energy which is greater for LuAlO3 than for YAlO3.