Low temperature synthesis and optical properties of the R2O3:Eu3+ nanophosphors (R3+: Y, Gd and Lu) using TMA complexes as precursors

Abstract

The R2O3:Eu3+ (R3+: Y, Gd and Lu) nanophosphors were synthesized with a low temperature thermolysis method using rare earth 1,3,5-benzenetricarboxylate (TMA) complexes as precursors. The R(TMA):Eu3+ (1mole %) complexes were synthesized using the co-precipitation method which complexes were then annealed at temperatures from 500 to 1000°C for 1h, yielding the cubic C-type R2O3:Eu3+ materials. The XPD patterns revealed no impurities in C-R2O3 obtained at any temperature. The Scherrer’s equation based on powder diffraction data confirmed an increase in crystallite size from 6 to 52nm with increasing annealing temperature from 500 to 1000°C for Y2O3, respectively, agreeing with the SEM and TEM data. Similar results were obtained for the other R2O3:Eu3+. The excitation spectra show a broad oxide to europium charge transfer absorption band at 260nm, i.e. O2−(2p)→Eu3+(4f6) LMCT, as well as the narrow lines assigned to the 4f–4f transitions of the Eu3+ ion. The characterization of the photoluminescence properties of the phosphors was also based on the analysis of the emission spectra and luminescence decay curves. The experimental intensity parameters (Ωλ), lifetimes (τ), as well as radiative (Arad) and non-radiative (Anrad) decay rates were calculated and discussed.