Effect of sintering temperature of Ce³⁺-doped Lu₃Al₅O₁₂ phosphors on light emission and properties of crystal structure for white-light-emitting diodes

The effect of the sintering temperature of Ce³⁺-doped Lu₃Al₅O₁₂ (Ce-LuAG) phosphors on the emission and properties of the crystal structure was studied. A cathodoluminescence peak at 317 nm, which was assigned to lattice defects, was exhibited in addition to emission peaks at 508 and 540 nm for the Ce-LuAG phosphors. The intensities of the 317 nm emission peak for the phosphors with mean particle diameters of 5.0 and 10.0 µm formed at a low sintering temperature of 1430 °C were higher than those for the phosphors with mean particle diameters of 18.0 and 20.5 µm formed at a high sintering temperature of 1550 °C. In contrast, the electroluminescence spectra for fabricated white-light-emitting diodes (LEDs) using the phosphors revealed that the intensity of the peak at 540 nm was strong for the mean particle diameters of 18.0 and 20.5 µm. The intensity of the 540 nm peak, which is attributed to the 4f→5d transition of the Ce³⁺ activator, showed a dependence on the sintering temperature. The relationship between the optical properties and the lattice defects is discussed.