A blue phosphor Ca 2 PO 4 Cl:Eu 2+ (CAP:Eu 2+ ) was synthesized by solid state reaction. The Ca 2 PO 4 Cl:Eu 2+ exhibited high quantum efficiency and excellent thermal stability. The luminescent intensity of Ca 2 PO 4 Cl:Eu 2+ was found to be 128 under excitation at 380 nm, 149 under 400 nm, and 247 under 420 nm as high as that of BaMgAl 10 O 17 :Eu 2+ . The optimal doping concentration was observed to 11 mol. of CAP:Eu 2+ . The energy transfer between Eu 2+ ions in CAP were occurred via electric multipolar interaction, and the critical transfer distance was estimated to be 1.26 nm. A mixture of blue-emitting Ca 2 PO 4 Cl:Eu 2+ , green-emitting (Ba,Sr) 2 SiO 4 :Eu 2+ and red-emitting CaAlSiN 3 :Eu 2+ phosphors were selected in conjunction with 400 nm chip to fabricate white LED devices. The average color-rendering index R a and correlated color temperature (T c ) of the white LEDs were found to be 93.4 and 4590 K, respectively. The results indicated that it was a promising candidate as a blue-emitting phosphor for the near-UV white light-emitting diodes.
- rare earths