[Preparation and Luminescent Properties of Blue Emitting Phosphor of Sr₃ (PO₄)₂: Eu²⁺ for White LED].

A series of Sr₃ (PO₄)₂: Eu²⁺ blue phosphors were synthesized by high temperature solid state method under N₂-H₂ reducing atmosphere. The crystal structures, excitation and emission spectra were characterized by X-ray diffraction (XRD) and Photoluminescence (PL), respectively. The results show that the Sr₃ (PO₄)₂: Eu²⁺ phosphor can be efficiently excited by the wavelengths ranging from 310 to 390 nm, and the excitation peak wavelength locates at 359 nm. A wide emission spectrum (~150 nm, originating from the 4ƒ 5d¹-->4ƒ of the Eu²⁺) with a peaking wavelength of 438 nm was obtained. Through the Gaussian fitting, we found that the emission band formed by two luminescence centers(430 and 459 nm), which indicated that the Eu²⁺ occupied two different Sr²⁺ sites in the substrate of Sr₃(PO₄)₂. As the Eu²⁺ doping concentration is 7%, the maximum luminous intensity was obtained. With the increasing of the doping concentration of the Eu²⁺, the concentration quenching effect occurred, and the emission peak wavelength has a red shift. The PL intensity of the Sr₃ (PO₄)₂: Eu²⁺ phosphor is about 1.3 times than that of the blue emitting phosphor BaMgAl₁₀O₁₇: Eu²⁺ (BAM) which means that it is a promising candidate for the blue phosphor material for white LED.