Gadolinium oxide single crystals: Optical properties and radiation resistance

Large-size high optical quality Gd2O3 single crystals were grown from solution at T = 1145 °C by Czochralski method. XRD analysis showed that the crystal structure is characterized by a single cubic phase (С-phase). Absorption spectra and luminescence properties of Gd2O3 doped with impurity Tb3+ ion were studied. The absorption spectrum is determined by electronic transitions in Gd3+ ion (spectral region of 245–315 nm) and interband electron transitions below 240 nm. Intraconfigurational radiative f-f transitions from 5D4 level in Tb3+ ion are clearly manifested upon both UV- and X-ray excitation. At the same time, 6PJ → 8S7/2 radiative transitions in Gd3+ ions are completely absent. This fact indicates high efficiency of nonradiative energy transfer from Gd3+ to Tb3+ ions. Thermo-luminescent spectroscopy shows the absence of charge carrier trapping centers, which proves the perfection of its crystal structure. The crystal under study shows high radiation resistance to high-energy (E = 10 MeV, D = 105 kGy) electron beam. However, the effects of irradiation appear only in the photoluminescence excitation spectra and thermally stimulated luminescence.