Synthesis and Photoluminescence Properties of Blue-Color Emitting Nanocrystalline Phosphors (Ba,Ca)₅(PO₄)₂SiO₄:Eu²⁺ for White Light-Emitting Devices

A series of (Ba,Ca)₅(PO₄)₂SiO₄:Eu²⁺ nanocrystalline phosphors were synthesized via a citrate sol-gel synthesis method. XRD, FE-SEM, and PL were exploited to characterize the crystal structure and luminescence properties of the prepared phosphors. The XRD results indicated that the pure Ba₅(PO₄)₂SiO₄ phase can be obtained at 900 ℃, and there is no crystal lattice perturbation induced by changing the doping the concentration ions Eu²⁺ and relative ratio of Ba²⁺ to Ca²⁺. Under the excitation of ultraviolet light, the (Ba,Ca)₅(PO₄)₂SiO₄:Eu²⁺ nanocrystalline phosphors consist of a broad band in the range of 400~550 nm due to the 4f⁶5d¹-4f⁷(8S7/2) charge transfer transitions of Eu²⁺ ions. The luminescence color of (Ba,Ca)₅(PO₄)₂SiO₄:Eu²⁺ nanocrystalline phosphors can be tuned from deep blue to blue by changing the relative ratio of Ba²⁺ to Ca²⁺. High quality blue light emission can be achieved in the phosphor (Ba_0.99Ca_0.01)₅(PO₄)₂SiO₄:Eu²⁺ by accurately adjusting the doping concentration of Eu²⁺ ions. The obtained blue phosphor (Ba,Ca)₅(PO₄)₂SiO₄:Eu²⁺ might be the promising candidates for UV-pumped white light-emitting devices and plant lighting.