Hydrothermal Preparation And Luminescent Property Of Eu³⁺ Doped Alkaline-earth Metal Double Phosphate

White light-emitting diodes（W-LEDs） have drawn muchattention in the lighting market because it has good performance such asenvironmental friendliness, energy saving, high brightness andlong lifetime.Nowadays, a usualwhite LED technology is to combine red/green/blue（RGB） phosphors with NUVInGaN-based LEDs, or to combine a blue LED with red/greenphosphors to generate white light.Due to theoutstanding thermal stability, stabilization of ionic charge inthe lattice and strong absorption band in the（near） ultravioletregion, rare earth-doped phosphate optical materials havebeen paid much attention in recent years.In this study, the red-emitting Ca₉Eu_1-xLn_x（PO₄）₇（Ln=Y, La, Gd） phosphor has beensynthesized by the hydrothermal method and its synthesizing technology and the influencesof introducing Ln³⁺（Ln =Y, La, Gd） on the properties of Ca₉Eu_1-xLn_x（PO₄）₇has been studied systematically.The results show that threetypes of Eu³⁺ site in the host were observed via the GSAS structuralrefinement method. The pH valueplayed a key role in the formation of Ca₉Eu（PO4）7nano-phosphor morphologies.With increasing pH values in the initial reactionsolution, the morphologies of samples changed from rods to spheres and their aspect ratios decreased at the same time.The results show that fluorescent material performance is the best when the filling degree of 80 %, the initial pH value is 7, the synthesis time is 24 hours under 180 ℃and the annealing time is 2 hours under 800℃.