화학공학소재연구정보센터
Materials Chemistry and Physics, Vol.139, No.1, 87-91, 2013
Enhancement of red emission intensity of Ca9Y(VO4)(7):Eu3+ phosphor via Bi co-doping for the application to white LEDs
The present investigation aims at the luminescence properties of CagY(VO4)(7):Eu3+, Bi3+ red phosphor materials. The red emission at 613 nm originating from 5D(0)-F-7(2) transition of Eu3+ in Ca9Y(VO4)(7) is enhanced strongly with Bi3+-V5+ couple as the sensitizer, under excitation either into the L-5(6) state or the D-5(2) state. The energy transfer from Bi3+-V5+ to Eu3+ is discussed. For a fixed Eu3+ concentration, there is an optimal Bi3+ concentration with 15 mol%, at which the maximum luminescence intensity of Eu3+ is achieved. The red emission of Ca9Y(VO4)(7):0.8Eu(3+), 0.15Bi(3+) (under 395 nm and 465 nm excitations) is stronger than that of commercial Y2O3:Eu3+ phosphor (under 395 nm and 467 nm excitations). Based on the ratios of the red emission at 613 nm to orange one at 592 nm, it is considered that the symmetry of Eu3+ site decreases with doping of Bi3+, leading to more opposite parity components. Lifetime and diffuse reflection spectra measurements indicate that the red emission enhancement is due to the enhanced transition probabilities from the ground state to L-5(6) and D-5(2) states of Eu3+ in the distorted crystal field. Therefore the present material is a promising red-emitting phosphor for white-light diodes with near-ultraviolet/blue GaN-based chips. (C) 2013 Elsevier B.V. All rights reserved.