Novel red-emitting Na2Mg(PO4)F:Eu3+ phosphors with abnormally high intensity of 5D0-7F4 transition

Novel single-phase red-emitting Na₂Mg(PO₄)F:Eu³⁺ phosphors are successfully synthesized in this work. The phase structure, surface morphology, and particle size are obtained. The photoluminescence excitation (PLE) spectrum, photoluminescence emission (PL) spectra, thermal quenching, and lifetime are also measured. The PLE spectrum exhibits a strong excitation peak at 395 nm, which matches the near-ultraviolet InGaN chip. The PL spectrum possesses a series of peaks associated with ⁵D₀→⁷F_J (J = 0–4) transition of Eu³⁺. The abnormal high emission peak located at 700 nm is due to the ⁵D₀→⁷F₄ transition, which is different from most Eu³⁺-doped phosphors. The optimum doping concentration (x) is 10% mol, and the quenching temperature (T_0.5) is over 470 K. The lifetimes of the prepared phosphors are in the range of milliseconds. The Commission International de I’Eclairage (CIE, 1931) coordinates were measured to be (0.621, 0.377). The white light-emitting diodes (w-LEDs) are also fabricated by the prepared phosphors and commercial phosphors. The above results indicate that the Na₂Mg(PO₄)F:Eu³⁺ fluorophosphate phosphors can be applied for w-LEDs.