Effect of K+ ions on the photoluminescence properties of Ca4.75(PO4)3Cl: 0.05Eu2+, 0.2Mn2+ phosphors

K+ ions were incorporated into Ca4.75(PO4)3Cl: 0.05Eu2+, 0.2Mn2+ Phosphors, which has a significant effect on the photoluminescence properties of phosphors. With increasing the K+ concentration (x value) in Ca4.75−xKx(PO4)3Cl: 0.05Eu2+, 0.2Mn2+ (x=0-0.15), the emission intensity of Eu2+ increases and reaches its maximum value at the x=0.1, and then decreases for the higher K+ concentrations, which can be explained by charge compensations and crystal lattice strain relaxing. The results show a potential for increasing the emission intensity of Ca4.75(PO4)3Cl: 0.05Eu2+, 0.2Mn2+ phosphors by properly doping K+ ions. •We synthesize K+-doped Ca5(PO4)3Cl : Eu2+, Mn2+ Phosphors.•K+ doping shows a positive effect on the emission intensity and thermal stability of Eu2+ in host.•We demonstrate the mechanism by charge compensations and crystal lattice strain relaxing.