Realizing an impressive red-emitting Ca9MnNa(PO4)7 phosphor through dual function based on disturbing structural confinement and energy transfer

In the field of white LEDs, the research and development of red phosphor has been confronting a challenge. In this paper, a novel red-emitting Ca9MnNa(PO4)7 (CMNPO) phosphor attributed to the 4T1(4G)–6A1(6S) transition of Mn2+ ions has been prepared by a high-temperature solid-state reaction. We utilize a chemical cosubstitution strategy to optimize the luminescent properties and realize an impressive red emission in CMNPO phosphor. The introduction of Zn2+/Mg2+ into CMNPO breaks the intrinsic structural confinement on Mn2+, which improves the red-emitting from Mn2+ in the narrow confines. The novelty for this work lies in realizing an efficient red phosphor by doping the trace amounts of Eu2+. Replacing partial Mn2+ with a trace amount of Eu2+, the CMNPO phosphor emits a dazzling red light and the quantum yield reach up to 82%. The intensity dependence of such a red emission on the trace amounts of Eu2+ doping is quantitatively analyzed. The substitution of Eu2+ ions plays a dual role in improving the luminescent properties, not only disturbing the structural confinement on Mn2+ but also transferring energy to Mn2+ efficiently. By employing it as red phosphor, we fabricate various high-performance white LEDs with low correlated color temperature (4642 K - 4956 K), high-color-rendering index (80.5 - 83.4). These findings show potential promise of CMNPO phosphor as a red phosphor in warm white LEDs, and open up new avenues for the exploration of novel red-emitting phosphors.