Doping Effect of Bi~(3+) on the Properties of YAG:Ce~(3+),Mn~(2+) Phosphor Ceramics for Warm WLEDs

A series of Bi~(3+)-doped YAG:Ce~(3+), Mn~(2+) ceramics was synthesized successfully by gel-casting method and structurally characterized by XRD and SEM. The doping effect and related mechanism of Bi~(3+) upon the luminescent property were studied. It can be assigned to the energy transfer of multipolar interaction from Bi~(3+) to Ce~(3+), leading to the improvement of emission intensity about 58% for 0.0001 Bi~(3+) and 0.05 Mn~(2+) doping. In addition, the emission is significantly red-shifted with the peak at 590 nm for the Y2.9939 Ce0.006 Bi0.0001 Al4.96 Mn0.02 Si0.02 O12 ceramic specimen with in-line transmittance 81.6% at 1100 nm. The LED module assembled from Y2.9939 Ce0.006 Bi0.0001 Al4.96 Mn0.02 Si0.02 O12 ceramic owns correlated color temperature(CCT) of 3960 K and luminous efficiency(LE) of 92 lm/W, implying that doping Bi~(3+) shows a good sensitization effect in the YAG:Ce~(3+), Mn~(2+) ceramic system and further serving as an attracting phosphor candidates for warm WLEDs applications.