A novel pure red phosphor Ca8MgLu(PO4)7:Eu3+ for near ultraviolet white light-emitting diodes

A novel red-emitting phosphor Ca8MgLu(PO4)7:Eu3+ was synthesized by a high-temperature solid-state reaction method. Its crystal structure, photoluminescence emission and excitation spectra, and decay time were investigated in detail. X-ray diffraction (XRD) results indicate that Ca8MgLu(PO4)7 crystallizes in single-phase component with a whitlockite-like structure and the space group R3c of β-Ca3(PO4)2. The emission spectrum shows a dominant peak at 612 nm due to the dipole 5D0→7F2 transition of Eu3+, and the luminescence intensity keeps increasing with increasing the content of Eu3+ to 100%. The excitation spectrum is coupled well with the emission of near ultraviolet (NUV) LED (380–410 nm). The CIE coordinates of Ca8MgLu(PO4)7:Eu3+ phosphor is (0.654, 0.346), being close to the standard value of National Television Standard Committee (NTSC) for red phosphor, (0.670, 0.330). The internal quantum efficiency of the phosphor is 69% under the excitation of 394 nm. The results show that Ca8MgLu(PO4)7:Eu3+ is a very appropriate red-emitting phosphor with a high ratio of red and orange for NUV-based white LEDs.