Synthesis and luminescent properties of rare earth (Sm3+ and Eu3+) Doped Gd2Ti2O7 pyrochlore nanopowders

Abstract

This work describes the synthesis and photoluminescent properties of rare earth (Sm3+ and Eu3+) doped Gd2Ti2O7 pyrochlore nanopowders. Pure-phase rare earth-doped Gd2Ti2O7 nanoparticles of approximately 20-50 nm in diameter, as evidenced from X-ray diffraction and electron microscopy analysis, are produced via the mixed metal-citric acid complex method. A temperature of 880 degrees C is identified for the formation of the crystalline pyrochlore phase, based on a differential thermal analysis of Gd2Ti2O7 precursor gels. From photoluminescence excitation and emission spectra, measured at 10 K and room temperature, the energy levels of Sm3+ and Eu3+ ions in Gd2Ti2O7 nanoparticles are obtained. The dependence of luminescence emission intensity and emission decays on rare earth concentration are measured and discussed. The strongest Sm3+ orange-reddish emission is observed for samples containing 2.5 at.% of Sm3+ ions, while in the case of Eu3+, the most intense emission is found for 15 at.% Eu3+ doping. The (4)G(5/2) level lifetime decreases with an increase in Sm3+ concentration, from about 5 ms (for 0.1-0.2 at.% of Sm3+) to 2.4 ms (for 2.5 at.% of Sm3+). With an increase in Eu3+ concentration in the Gd2Ti2O7 nanoparticles, the Eu3+ D-5(0) level lifetime decreases from similar to 5.9 ms (for 0.5 at.% of Sm3+) to 3.1 ms (for 15 at.% of Sm3+). (C) 2014 Elsevier B.V. All rights reserved.