Synthesis and luminescent properties investigation of novel red emission phosphors Ca7Zn2(PO4)6: Re3+ (Re =Eu, Sm and Pr)

Abstract

A series of new red emission phosphors Ca7Zn2(PO4)6: Re3+ (Re3+ = Eu3+, Sm3+, Pr3+) are synthesized by solid state reaction. The crystal structure and microstructure are systematically investigated by X-ray diffraction Rietveld structure refinement, scanning electron microscopy and energy dispersive spectrometer. The photoluminescence properties of Ca7Zn2(PO4)6: Re3+ (Re3+ = Eu3+, Sm3+, Pr3+) are studied in detail. The results show that Eu3+, Sm3+ or Pr3+ single doped Ca7Zn2(PO4)6 could emit red emissions with dominate peaks at 612 nm, 602 nm and 612 nm, respectively, which are attributed to the characteristic transitions (5D0-7F2, 4G5/2-6H7/2 and 3P0-3H6) of Eu3+, Sm3+ and Pr3+. The concentration dependent emission spectra of Ca7Zn2(PO4)6: Sm3+ are studied as well. A charge compensator Li2CO3 is added in Sm3+ doped Ca7Zn2(PO4)6 and the emission intensity is compared with the commercial red phosphor Y2O3:Eu3+. The room temperature fluorescence lifetimes of Ca7Zn2(PO4)6: Re3+ (Re3+ = Eu3+, Sm3+, Pr3+) are measured and the average lifetimes are evaluated. Finally, the Commission Internationale de L'Eclairage chromaticity coordinates and their color purity are calculated.