Ce and Tb doped CaGd(AlO)(BO) phosphors: synthesis, tunable photoluminescence, thermal stability, and potential application in white LEDs.

Novel blue-green-emitting CaGd(AlO)(BO):Ce,Tb phosphors were successfully synthesized traditional high temperature solid reaction method. X-ray diffraction, luminescence spectroscopy, fluorescence decay time and fluorescent thermal stability tests have been used to characterize the as-prepared samples. The energy transfer from Ce to Tb ions in the CaGd(AlO)(BO) host has been demonstrated to be by dipole-dipole interaction, and the energy transfer efficiency reached as high as 83.6% for CaGd(AlO)(BO):0.01Ce,0.6Tb. The critical distance was calculated to be 9.44 Å according to the concentration quenching method. The emission colour of the obtained phosphors can be tuned appropriately from deep blue (0.169, 0.067) to green (0.347, 0.494) through increasing the doping concentrations of Tb. Moreover, the CaGd(AlO)(BO):0.01Ce,0.6Tb phosphor possessed excellent thermal stability at high temperature, and the emission intensity at 423 K was about 87% of that at 303 K. Finally, the fabricated prototype LED device with a BaMgAlO:Eu blue phosphor, CaAlSiN:Eu red phosphor, CaGd(AlO)(BO):0.01Ce,0.6Tb green phosphor and 365 nm-emitting InGaN chip exhibited bright warm white light. The current study shows that CaGd(AlO)(BO):0.01Ce,0.6Tb can be used as a potential green phosphor for white LEDs.