Joanna Trojan-Piegza

Structural and spectroscopic characterization of Lu2O3:Eu nanocrystalline spherical particles

Spherical particles of Lu2O3:x% Eu, with x varying from 0% to 10% with respect to Lu, were prepared by precipitating hydroxides with urea at 80 °C and subsequently decomposing these hydroxides to oxides at 650 °C. TEM pictures revealed that the spherical particles were very uniform in size and their diameters were about 130 nm. Each of the particles consisted of crystallites about 20 nm in diameter. Luminescence and excitation spectra contained all the characteristic features of the Eu3+ ion. The most intense line in the emission was located around 611 nm. Energy transfer was observed from the Eu3+ ions occupying the S6(C3i) centrosymmetric site to the Eu3+ located in the non-centrosymmetric position of C2 symmetry. The decay kinetics were slightly non-exponential, especially for the lowest dopant concentrations. At liquid nitrogen temperature the average decay time for the 0.2% powder was shorter by about 40% compared to the 3–10% materials. At room temperature the average decay time varies only slightly. Rise times were observed for all concentrations at room temperature but only for higher concentrations at liquid nitrogen temperature. This effect is in contrast to that of nanoparticles of Lu2O3:Eu prepared using different synthesis procedures.