Single-Phased White-Light Phosphors Ca₉Gd(PO₄)₇:Eu²⁺,Mn²⁺ under Near-Ultraviolet Excitation

Abstract

Single-phased white-light-emitting phosphors Ca9Gd(PO4)7:Eu2+,Mn2+ were synthesized by solid state reactions. Tuning the Eu2+/Mn2+ ratio via the energy transfer varied the emission hue of Ca9Gd(PO4)7:0.007Eu2+,xMn2+ from blue-greenish (0.219, 0.371) to white-light (0.326, 0.328) and eventually to red (0.625, 0.307). The mechanism of transferring energy from a sensitizer Eu2+ to an activator Mn2+ in Ca9Gd(PO4)7:Eu2+,Mn2+ phosphors was demonstrated to be an electric dipole−quadrupole interaction. Combining a near-UV 380 nm chip and a white-emitting Ca9Gd(PO4)7:0.007Eu2+,0.02Mn2+ phosphor produced a white-light near-UV LED, demonstrating CIE chromaticity coordinates of (0.312, 0.327) and a color temperature of 6569 K.