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Achieving the desired color temperature and color rendering index in light sources is challenging because of the deficiency of certain color components, notably cyan in the illumination spectra. In this investigation, we successfully synthesized orthogonal Ca5Ga6O14: Bi3+ (CGO: Bi3+) phosphors with space group Cmc21, featuring two distinct Ca(1) and Ca(2) sites. Under the excitation of 335 nm, a broad cyan emission with a 495 nm peak was observed. Gaussian peak fitting revealed two sub-peaks at 445 and 500 nm, originating from the emission of Bi3+ occupying Ca(1) and Ca(2) sites, respectively. As Bi3+ doping concentration increased, the luminescence experienced a red shift, attributed to the cooperative impact of crystal field splitting and electron cloud rearrangement. Through the substitution of Sr2+ ions, we achieved a 2.15 times enhancement in emission intensity and an increase in lifetime from 0.451 to 0.551 μs. This substitution also led to a consistent increase in the relative emission percentage of Bi(1) from 46.5% to 73.1%, while that of Bi(2) decreased from 70.5% to 44.9%. It is likely a result of some Bi3+ ions originally situated in the Ca(2) site migrating to the Ca(1) site. Finally, the introduction of Na+ ions for charge compensation resulted in a 20.18% increase in the luminescence intensity and an enhanced quantum efficiency of 84.21%. This CGO: Bi3+ phosphor holds promise as a potential cyan phosphor for white light sources. [ABSTRACT FROM AUTHOR]

Whitlockite β-Ca3(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 β-Ca3(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: 0.04Eu2+ 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: 0.04Eu2+ 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: 0.04Eu2+ 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. [ABSTRACT FROM AUTHOR]