Structural and optical properties of Vernier phase lutetium oxyfluorides doped with lanthanide ions: interesting candidates as scintillators and X-ray phosphors

Undoped, Ce3+, Pr3+ and Eu3+ doped lutetium oxyfluoride submicrometre powders have been preparedby a simple coprecipitation procedure in water. The synthesized samples are Vernier single phases witha stoichiometry assigned to Lu10O9F12, as demonstrated by X-ray powder diffraction. The structuraldisorder of the host matrix significantly affects the optical emission spectra of the lanthanide dopedsamples as well as their vibrational spectra. The observed bandwidths of the FTIR spectrum andRaman scattering of the undoped sample are consistent with a very disordered nature of the host. Froman analysis of the emission spectra of the Eu3+ doped sample it was found that different sitesaccommodating the lanthanide ions are present in the crystal structure. The Pr3+ and Ce3+ dopedoxyfluoride samples show radioluminescence emission both in the UV and visible regions. The UVemission is due to lanthanide 4d–5f transitions, differently from the behavior observed for Ce3+ and Pr3+doped Lu2O3, showing no UV emission. Considering the high mass density (close to 9 g cmÀ3), and thesuitable location of rare earth ion electronic levels in the material band gap, as demonstrated by theobservation of radiative emissions for all activators, the materials under investigation can be consideredinteresting candidates for scintillator or phosphor materials in the UV and visible regions.