A broadband emitting Sr 8 MgGa(PO 4 ) 7 :Eu 2+ phosphor for application in white light-emitting diodes with excellent color rendering index

Whitlockite β -Ca 3 (PO 4 ) 2 -type materials have multiple crystallographic sites for occupying by rare earth ions to achieve a strong and broadband emitting covering the spectra from cyan to deep red and various abundant heterogeneous substitution ability to develop new luminescent materials. In this work, a broadband emitting Sr 8 MgGa(PO 4 ) 7 :Eu 2+ (SMGP) phosphor, deriving from β -Ca 3 (PO 4 ) 2 host by cations substitution, was prepared by solid state reaction at high temperature. Based on the Rietveld refinement results, SMGP host possesses a monoclinic system with a space group C2/m. The optimized doping concentration was determined to be 0.04. The SMGP: 0.04Eu 2+ sample exhibit strong absorption at the wavelength of 250–500 nm, and a broadband emission from 450 to 800 nm covering the spectra from cyan to deep red. However, the SMGP: 0.04Eu 2+ phosphors exhibit poor thermal stability with activation energy as 0.156 eV. By adjusting the composition of the trivalent ions Ga 3+ /Lu 3+ , controllable emission color from green to yellow can be achieved in the Sr 8 MgGa 1-x Lu x (PO 4 ) 7 :Eu 2+ solid solution phosphors. Finally, a white light-emitting diodes (LED) lamp was prepared by coating the mixtures of SMGP: 0.04Eu 2+ phosphors and BaMgAl 10 O 17 :Eu 2+ phosphors on the surface of 400 nm near-ultraviolet chip. The optimized white LED lamp exhibits a correlated color temperature of 2991 K and a good color rendering index of 90.2. These results demonstrate the commercialized prospect of SMGP: Eu 2+ materials as a broadband emitting phosphor for application in solid state lighting.