Spectral, energy resolution properties and green-yellow LEDs applications of transparent Ce3+:Lu3Al5O12 ceramics

Transparent Ce3+:Lu3Al5O12 ceramics were successfully fabricated by combining tape-casting method and direct-forming method with solid-state sintering. The in-line optical transmittance and absorption spectra of as-sintered and air-annealed Ce:LuAG ceramics were comparely studied. XPS spectra indicated Ce3+ and Ce4+ ions co-existed in the prepared ceramics. Energy levels splitting of Ce3+ in LuAG hosts were investigated based on broad-band emission from 500 nm to 700 nm resulting from the electron transitions from 5d(1) excited levels (D-2) to 4f ground state of Ce3+ (F-2(5/2), F-2(7/2)). The fluorescence lifetimes at 540 nm were 50-60 ns and energy resolution of 12% was achieved at Na-22 (511 keV). When collaborated with InGaN-GaN LED chips, a maximum CRI of 55.8 with LE as high as 223.4 lm/W were demonstrated, indicating that Ce:LuAG ceramics had a promising potential for white light-emitting diodes. (C) 2016 Elsevier Ltd. All rights reserved.