Crystal Structure and Luminescence Properties of a Thermally Stable Single-Phase White Emitting Phosphor CaSr2(PO4)2: Dy3+, Li+

Abstract

Single-phase CaSr2(PO4)2:Dy3+,Li+ phosphors were prepared using the high-temperature solid-state method in the air. To characterize the luminescence properties of the synthesized phosphors, Powder X-ray diffraction patterns (XRD), scanning electron microscopy images (SEM), photoluminescence spectra, and concentration-dependent emission spectra were measured to characterize the luminescence properties of the synthesized phosphors. The results showed that the CaSr2(PO4)2:Dy3+,Li+ phosphors exhibited white luminescence, and the emission spectra of the phosphors consisted of two sharp peaks at ≈486 and ≈578 nm (the most intense one). The optimum concentration of Dy3+ doping was determined to 0.06 mol.%. On the basis of the Dexter's theory, the mechanism of energy transfer between the Dy3+ ions was determined to dipole–dipole interactions. The results of the temperature-dependent luminescence confirmed that the as-prepared phosphors are proved to be promising UV-convertible material capable of white light emitting in UV-LEDs due to its excellent thermal stability and luminescence properties. Luminescence intensity and decay time of the CaSr2(PO4)2:Dy3+,Li+ phosphors were improved remarkably with the addition of charge compensators (Li+ ions), which would promote their applications in white light-emitting diodes based on the near-UV chip.