A novel dazzling Eu ³⁺ ‐doped whitlockite‐type phosphate red‐emitting phosphor for white light‐emitting diodes

Abstract

Abstract A series of novel red‐emitting Ca 8 ZnLa 1− x Eu x (PO 4 ) 7 phosphors were successfully synthesized using the high‐temperature solid‐state reaction method. The crystal structure, photoluminescence spectra, thermal stability, and quantum efficiency of the phosphors were investigated as a function of Eu 3+ concentration. Detailed analysis of their structural properties revealed that all the phosphors could be assigned as whitlockite‐type β‐Ca 3 (PO 4 ) 2 structures. Both the PL emission spectra and decay curves suggest that emission intensity is largely dependent on Eu 3+ concentration, with no quenching as the Eu 3+ concentration approaches 100%. A dominant red emission band centered at 611 nm indicates that Eu 3+ occupies a low symmetry sites within the Ca 8 ZnLa(PO 4 ) 7 host lattice, which was confirm by Judd‐Ofelt theory. Ca 8 ZnLa 1− x Eu x (PO 4 ) 7 phosphors exhibited good color coordinates (0.6516, 0.3480), high color purity (~96.3%), and high quantum efficiency (~78%). Temperature‐dependent emission spectra showed that the phosphors possessed good thermal stability. A white light‐emitting diode ( LED ) device were fabricated by integrating a mixture of obtained phosphors, commercial green‐emitting and blue‐emitting phosphors into a near‐ultraviolet LED chip. The fabricated white LED device emits glaring white light with high color rendering index (83.9) and proper correlated color temperature (5570 K). These results demonstrate that the Ca 8 ZnLa 1− x Eu x (PO 4 ) 7 phosphors are a promising candidate for solid‐state lighting.