Luminescence properties of Y3+ stabilized Gd3Al5O12:Tb3+/Ce3+ phosphors with yellow light-emitting for warm white LEDs

The new system of [(Gd0.9Y0.1)0.9-xTb0.1Cex]AG phosphors have been successfully obtained by using a modified co-precipitation method which include the precursor synthesis and post treatment at 1300 °C. The crystal structure stabilization, morphology, PL/PLE spectra, fluorescence decay analysis and thermal property have been studied in detail. The metastable GdAG:Tb3+/Ce3+ samples could be effectively stabilized via smaller 10 at% Y3+ doping, which can develop a new phosphor of [(Gd0.9Y0.1)0.9-xTb0.1Cex]AG for exploring the field of the opto-functionality. The presence of Gd3+ and Tb3+ excitation bands in the PLE spectra monitoring the Ce3+ yellow emission directly provides an evidence of Gd3+→Ce3+ and Tb3+→Ce3+ energy transfer. The [(Gd0.9Y0.1)0.9-xTb0.1Cex]AG phosphors with good dispersion show various luminescence properties monitoring at 275 nm, 331 nm and 452 nm excitation, respectively. The optimized (Gd0.9Y0.1)0.89Tb0.1Ce0.01]AG phosphor has a red-shifted emission and the applicable emission intensity because of the energy transfer of Gd3+→Ce3+ and Tb3+→Ce3+, thus being more suitable for the application of warm-white lighting than YAG:Tb3+/Ce3+ and LuAG:Tb3+/Ce3+. The Stokes shift have been calculated through the Gaussian fitted curves of emission spectra, indicating that the doping of Ce3+ does not obviously change the splitting degree of 5d orbit. The quenching concentration was determined to be 1.0 at%, and the quenching mechanism was determined to be the exchange reaction between Ce3+. The temperature-dependent analysis has been performed and the results indicated that the [(Gd0.9Y0.1)0.89Tb0.1Ce0.01]AG phosphors possesses good thermal stability. The fluorescence decay analysis shows that the lifetimes of Tb3+ and Ce3+ emission decrease with the Ce3+ content increasing. The [(Gd0.9Y0.1)0.89Tb0.1Ce0.01]AG phosphors developed in this work are expected to be widely used in the lighting and optical display areas.