Optimization of photoluminescence of Y2O3:Eu and Gd2O3:Eu phosphors synthesized by thermolysis of 2,4-pentanedione complexes

Abstract

Spherical shaped nanoparticles of series Y2-xEuxO3 (x = 0.06, 0.10, 0.20, and 2) and Gd2-xEuxO3 (x = 0.06, 0.10) were prepared by thermolysis of 2,4-pentanedione complexes of Y, Gd, and Eu. The bixbyite phase of Gd2-xEuxO3 samples was formed at 500 degrees C, whereas the thermal decomposition of Y and Eu complexes' mixtures occurred at higher temperatures. Linearity in the concentration dependence on lattice parameter confirmed the formation of solid solutions. The distribution of Eu3+ in Gd2-xEuxO3 was changed with thermal annealing: in the as-prepared sample (x = 0.10) the distribution was preferential at C-3i sites while in the annealed samples, Eu3+ were distributed at both C-2 and C-3i sites. Rietveld refinement of site occupancies as well as emission spectra showed a random distribution of cations in Y2-xEuxO3. The photoluminescence (PL) measurements of the sample showed red emission with the main peak at 614 nm (D-5(0)-F-7(2)). The PL intensity increased with increasing concentration of Eu3+ in both series. Infrared excitation was required to obtain good Raman spectra. The linear dependence of the main Raman peak wavenumber offers a non-destructive method for monitoring the substitution level and its homogeneity at the micron scale.