Orange-red-emitting CaTi4(PO4)6:Eu3+ phosphor for white LEDs: synthesis and luminescence properties

CaTi 4 (PO 4 ) 6 : x Eu 3+ phosphors are successfully synthesized under air condition by high-temperature solid-state method. The crystal structure, morphology, energy spectrum, atomic percentage, elemental mapping, and luminescence properties are investigated, respectively. Monitored at 594 nm, the excitation spectral bands of CaTi 4 (PO 4 ) 6 :Eu 3+ phosphor in the range of 210–550 nm are assigned to the O 2− –Eu 3+ charge transfer band (CTB) and the 7 F 0  →  5 H 3 , 5 L 7 , 5 L 6 , 5 D 1 , 5 D 2 , 5 D 3 , and 5 D 4 transitions of Eu 3+ ion. With excitation at 394 nm, CaTi 4 (PO 4 ) 6 :Eu 3+ phosphor emits orange-red light with the chromaticity coordinates (0.548, 452), and the emission spectral bands in the region from 575 to 720 nm are attributed to the 5 D 0  →  7 F 1 , 7 F 2 , 7 F 3 , and 7 F 4 transitions of Eu 3+ ion. The optimal doping concentration of Eu 3+ ion is ~ 8 mol%. The lifetime of CaTi 4 (PO 4 ) 6 :Eu 3+ phosphors decreases from 1.87 to 0.97 ms with increasing Eu 3+ concentrations from 1 to 10 mol%. CaTi 4 (PO 4 ) 6 :Eu 3+ phosphor has a good thermal stability. The experimental results indicate that CaTi 4 (PO 4 ) 6 :Eu 3+ phosphor has an application prospect in white light-emitting diodes (LEDs) based on the near ultraviolet (~ 394 nm) LED chip.