Locations of the energy levels of lanthanide ions in Gd2O3 single crystals

Large-sized, high optical quality Gd2O3 single crystals were grown from a solution at T = 1145 degrees C using Czochralski method. XRD analysis showed that the crystal structure is characterized by a single cubic (bixbyite) phase (c-phase). The absorption spectra and luminescence properties of Gd2O3 doped with Eu3+ and Tb3+ impurity ions were studied. The absorption spectrum of Gd2O3:Eu in the short wavelength region is mainly due to charge transfer transitions from O2-to Eu3+ (240-290 nm), which overlap with the Urbach tail of the host-absorption. Additionally, electronic transitions in Eu3+ (320-540 nm) and Gd3+ (245-315 nm) lanthanide ions contribute to the absorption spectrum. Intraconfigurational radiative f - f transitions in impurity ions are clearly observed upon both UV-and X-ray excitations. However, 6PJ & RARR; 8S7/2 radiative transitions in Gd3+ ions are completely unobservable. Based on the obtained spectroscopic data, the energy positions of the ground state of all di-and trivalent lanthanide ions, as well as the energies of intraconfigurational f - f and interconfigurational f - d electronic transitions in Gd2O3 crystals with a cubic structure, are calculated. The proposed electronic energy diagram is used to discuss efficient energy transfer between lanthanide ions.