A broadband emitting Sr8MgGa(PO4)7:Eu2+ phosphor for application in white light-emitting diodes with excellent color rendering index

Whitlockite beta-Ca-3(PO4)(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 Sr8MgGa(PO4)(7):Eu2+ (SMGP) phosphor, deriving from beta-Ca-3(PO4)(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 Ga3+/Lu3+, controllable emission color from green to yellow can be achieved in the Sr8MgGa1-xLux(PO4)(7):Eu2+ solid solution phosphors. Finally, a white light-emitting diodes (LED) lamp was prepared by coating the mixtures of SMGP: 0.04Eu(2+) phosphors and BaMgAl10O17:Eu2+ 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: Eu2+ materials as a broadband emitting phosphor for application in solid state lighting.

Automated summary

The study focuses on the preparation of broadband emitting Sr8MgGa(PO4)(7):Eu2+ (SMGP) phosphor through solid state reaction, achieving wide emission from cyan to deep red, though with poor thermal stability; controllable emission color can be achieved through adjusting the composition of the solid solution phosphors; the optimized white LED lamp prepared showed good color rendering and correlated color temperature.