Hydrothermal synthesis and luminescent properties of Ca3(PO4)2: Dy3+ white-emitting phosphors

The white-emitting Ca3(PO4)2: Dy3+ phosphors were prepared via hydrothermal synthesis. The phosphors were characterized by XRD, TEM, SEM, EDS, GSAS structural refinement and PL spectroscopy, respectively. Rietveld refinement demonstrated that the Ca3(PO4)2 crystal structure consisted of [PO4] tetrahedrons filled with Ca atoms. Dy3+ ions occupied high-symmetry sites due to the emission intensity of 4F9/2 → 6H15/2 was strongest. Moreover, the pH value and calcination temperature had important effects on the phosphor morphology and luminescent properties. The morphology of the samples changed from long-rod to short-rod and sphere and the size reduced as the pH value in the initial reaction solution increased. The samples with pH of 7 had the best luminescence properties, and the precursor before calcination corresponded to Ca4P2O9. With the calcination temperature of the precursor with pH of 7 increased, the phosphor morphology changed from nanorods to grains with diameters of about 1 μm, and the luminescence properties were improved continuously. The CIE coordinate of Ca3(PO4)2: Dy3+ phosphor was (0.283, 0.343). The Ca3(PO4)2: Dy3+ phosphor has better application prospects for white light-emitting diodes.