Li3Gd3Te2O12:Eu3+- an intense red phosphor for solid state lighting applications

Li3Gd3−3xEu3xTe2O12 (x=0.05−1.0) phases with garnet structure were synthesized by high temperature solid state reaction and the photoluminescence properties were investigated. The appearance of bands due to intra 4f transitions of Gd3+ in the excitation spectra recorded by monitoring the 612nm emission line of the activator indicates Gd3+→Eu3+ energy transfer in this host lattice. Under 395nm excitation, the electric dipole transition is predominant in the emission spectrum of Eu3+ and is in agreement with the C2 point group (noncentrosymmetric) of the EuO8 polyhedron. The critical concentration of the Eu3+ activator in this series was found to be 0.6 (x=0.2) above which, concentration quenching occurs. The emission intensity of the phosphor composition, Li3Gd2.4Eu0.6Te2O12 is ~4 times that of the commercial sample of Y2O3:Eu3+ phosphor.