The temperature influence on the optical and structural properties of the Ge₂Y_1.96Eu_0.047 crystalline phase

Full text: Nanoparticles of yttrium germanate materials containing europium were synthesized by the polymeric precursor method and treated at different temperatures (900, 100 and 1100 ° C). We evaluated their structure and optical properties as a function of annealing temperature. X-ray diffraction (XRD), infrared vibrational spectroscopy (FTIR), Raman spectroscopy, diffuse reflectance spectroscopy (DRS) and emission and excitation photoluminescence spectroscopy (PL, PLE) these techniques were used to study these materials until the moment. It was observed in the diffractograms that when increasing the treatment temperature of the samples the presence of some low intensity spurious peaks disappear and the peaks referring to the Bragg diffractions become more defined, this is an evidence of sample homogenization and single phase formation desired: Ge₂Y_1.96Eu_0.047. It was performed the refinement of the crystalline structure of these materials, obtaining a value of gof equal 1.5; the value close to the unit shows a good quality of refinement. Diffuse reflectance studies show an intense signal, ~ 87%, from ultraviolet to near infrared regions and the optical bandgap is superior to 4.5 eV. The Ge₂Y₂O₇ matrix doped with 1% Eu present high and interesting PL emission in the red and orange regions. The Judd Ofelt parameters of the samples were determined and evaluated. (author)