Luminescence Enhancement of Red‐Emitting Sr₉MnK(PO₄)₇ Phosphor via Energy Transfer and Charge Compensation

Abstract

It is an urgent need to explore high‐efficiency and high‐purity red‐emitting phosphors in white light‐emitting diodes (LEDs) application. Herein, the synthesis and luminescence properties of Mn‐based Sr9MnK(PO4)7 phosphor are reported. X‐ray diffraction (XRD) measurement and Rietveld structural refinement confirm that Sr9MnK(PO4)7 is crystallized in the trigonal Sr9Fe1.5(PO4)7 type structure with the space group of R 3 ¯ m (166). Eu2+‐doped Sr9MnK(PO4)7 phosphor exhibits a broad excitation spectrum peaked at 394 nm and emits bright reddish‐orange light centered at 610 nm. Moreover, the introduction of the Ce3+ ion substantially enhances the intensity of Mn2+ emission. Here, Ce3+ acts as a charge compensator rather than a sensitizer, as confirmed by spectral analysis and various chemical techniques. On the base of the energy transfer between Eu2+ and Mn2+ coupled with charge compensation, a high‐brightness red‐emitting Sr9MnK(PO4)7:Eu2+,Ce3+ phosphor is obtained.

Co-Doping Effect of Mn2+ and Eu3+ on Luminescence in Strontiowhitlockite Phosphors

“…It appears that Mn 2+ ions in the octahedra site played a critical role in the structure stabilization, similar to the Mg 2+ ions in strontiowhitlockite. A similar structure formation was found in some related works, for example for Sr 9 MnK(PO 4 ) 7 :Eu 2+ ,Ce 3+ [33] or Sr 8 MgCe(PO 4 ) 7 :Eu 2+ ,Mn 2+ [34] on Sr-based phosphors.…”