Electronic structure and photoluminescence property of a novel white emission phosphor Na_3MgZr(PO_4)_3:Dy~(3+) for warm white light emitting diodes

To explore suitable single-phase white emission phosphors for warm white light emitting diodes, a series of novel phosphors Na₃MgZr(PO₄)₃:xDy³⁺ (0≤ x≤ 0.03) is prepared, and their phase purities as well as photoluminescence properties are discussed in depth via x-ray diffraction structure refinement and photoluminescence spectrum measurement. The electronic structure properties of the Na₃MgZr(PO₄)₃ host are calculated. The results reveal that Na₃MgZr(PO₄)₃ possesses a direct band gap with a band gap value of 4.917 eV. The obtained Na₃MgZr(PO₄)₃:Dy³⁺ phosphors are all well crystallized in trigonal structure with space group R3c, which has strong absorption around 365 nm and can generate warm white light emissions peaking at 487, 576, and 673 nm upon ultraviolet excitation, which are attributed to the transitions from ⁴F_9/2 to ⁶H_15/2, ⁶H_13/2, and ⁶H_11/2 of Dy³⁺ ions, respectively. The optimal doping content, critical distance, decay time, and Commission International de L'Eclairage (CIE) chromaticity coordinates are investigated in Dy³⁺ ion-doped Na₃MgZr(PO₄)₃. The thermal quenching analysis shows that Na₃MgZr(PO₄)₃:Dy³⁺ has a good thermal stability, and the thermal activation energy is calculated. The performances of Na₃MgZr(PO₄)₃:Dy³⁺ make it a potential single-phase white emission phosphor for warm white light emitting diode.