Synthesis, luminescent properties and energy transfer in Tb3+ and Eu3+ co-doped Li3Ba2Gd3 (MoO4)(8) phosphors for W-LED's

Abstract

For the first time, single phase monoclinic Li3Ba2Gd3 (MoO4)8: 0.08 Tb3+,yEu3+ (0, 0.005, 0.02, 0.04, 0.06, 0.08 and 0.10 mol) nano phosphors were prepared by the simple mechanochemically assisted direct solid state reaction method at room temperature. Their crystal structures, luminescence properties, energy transfer mechanism and life time were studied in detail. At the excitation wavelength of 378 nm, the emission spectra of Li3Ba2Gd3 (MoO4)8: 0.08 Tb3+,yEu3+ (0, 0.005, 0.02, 0.04, 0.06, 0.08 and 0.10 mol) phosphors exhibit the characteristic emissions of Tb3+ and Eu3+ ions at around 545, 594 and 615 nm due to energy transfer from Tb3+ ions to Eu3+ ions. It is confirmed from the results that electric dipole–dipole interaction phenomena is the main cause for having energy transfer from Tb3+ to Eu3+ ions in Li3Ba2Gd3 (MoO4)8 host. The CIE coordinates of the prepared nano phosphors illustrate that by changing the ratio of Eu3+ ions the white light emission can be realized from Li3Ba2Gd3 (MoO4)8 phosphor and it coexist very close to an ideal white chromaticity coordinates (0.33, 0.33). All properties show that Li3Ba2Gd3 (MoO4)8: 0.08 Tb3+, 0.005 Eu3+ nano phosphor is a promising material for single-phase phosphor based white light emitting diodes.