Fine yellow GdSr2AlO5:Ce3+ phosphor for white LEDs prepared by high energy ball milling process

Abstract

Gd1−xSr2AlO5:xCe3+ (GSA:Ce3+) yellow phosphors were prepared by a high-energy ball milling method. The X-ray diffraction pattern of GSA:Ce3+ phosphors revealed a complex tetragonal structure corresponding to the GdSr2AlO5 and GdSrAlO4 phases. The photoluminescence (PL) excitation spectra showed a dominant excitation wavelength at 438nm due to the 4f–5d transition of Ce3+ ions in the GSA host lattice. The photoluminescence (PL) spectra with 438nm excitation displayed yellow emission corresponding to the 5d–4f transition of Ce3+ ions. Doping a GdSr2AlO5 host lattice with Ce3+ ions at 2mol% concentration or higher (corresponding to x=0.02 in the Gd1−xSr2AlO5:xCe3+ formula) led to a quenching of the PL intensity. The emission peak of the resulting GSA:Ce3+ phosphor shifted to the red region due to an increase in the crystal splitting for the Ce3+ ions. A white light-emitting diode (WLED) fabricated by combining a blue 460nm LED chip with the GSA:Ce3+ phosphor exhibited the CIE chromaticity coordinates of (0.347, 0.311).