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

Abstract

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. KeywordsSr8MgGa(PO4)7:Eu2+ • Broadband emitting phosphors • Excellent color rendering index • Whitlockite β-Ca 3 (PO 4 ) 2 -type materials • Multi-luminescent centers • White light-emitting diodes * Jiangcong Zhou

Adjustable ultraviolet and white light dual emission phosphor Y2Sr(Ga1−yAly)4SiO12:xPr3+ for health lighting

“…The decay curves are monitored for the Pr 3+ emission. All curves are fitted well to the biexponential decay model based on the following formula: 44 I t = I 0 + A 1 exp(− t / τ 1 ) + A 2 exp(− t / τ 2 ),where I t and I 0 are the emission intensities, A 1 and A 2 are the fitting constants, t is the time, and τ 1 and τ 2 are the lifetimes of the exponential component. The average decay time value τ is acquired as: τ = ( A 1 τ 1 2 + A 2 τ 2 2 )/( A 1 τ 1 + A 2 τ 2 ).The corresponding average lifetimes are calculated to be 1.85 μs (320 nm), 21.75 μs (486 nm) and 13.75 μs (618 nm), respectively.…”

“…The decay curves are monitored for the Pr 3+ emission. All curves are fitted well to the biexponential decay model based on the following formula:44…”