Luminescent properties of Sr₅(PO₄)₃ Cl: Eu²⁺, Mn²⁺ as a potential phosphor for UV-LED-based white LEDs

Eu²⁺ and Mn²⁺ co-activated Sr₅(PO ₄)₃Cl phosphors with blue and orange color double emission bands, under a broad-band excitation wavelength range of 340-400 nm, were synthesized by the solid-state reaction. It was found that the processing parameters, including the fluxes, annealing time and activators concentrations, affect the emission intensity and other luminescent properties. Energy transfer between Eu²⁺ and Mn²⁺ was discovered and the transfer efficiency was also estimated based on relative intensities of Eu²⁺ and Mn²⁺ emission. Thus the relative strength of blue and orange emission intensities could be tuned by varying the relative concentration of Eu²⁺ and Mn²⁺. Since the photoluminescence excitation spectra of the newly developed Sr₅(PO₄) ₃Cl:Eu²⁺, Mn²⁺ phosphors exhibit a strong absorption in the range of 340-400 nm, they are promising for producing UV-LED-based white LEDs.