Mn 4+ -activated Sc-based hexafluoride red phosphor K 5 Sc 3 F 14 : Synthesis, luminescence, and its applications in blue-pump WLEDs.

Due to the advantages of low phonon energy, structural diversity, excellent thermal stability and optical properties, fluoride compounds have sparked considerable research attention. On this foundation, a novel red-emitting phosphor, K ₅ Sc ₃ F ₁₄ :Mn ⁴⁺ (abbreviated as KSF:Mn ⁴⁺ ), was successfully designed and synthesized via a conventional co-precipitation process. The phosphor was comprehensively analyzed in terms of its phase, structure, morphology, elemental composition, and optical performance. Under blue light (473 nm) excitation, seven discernible emission peaks appear at 599, 609, 613, 622, 630, 634, and 647 nm, which can be attributed to the ² E _g to ⁴ A _2g transition of the Mn ⁴⁺ ions. Furthermore, the optimal molar ratio of K ₅ Sc ₃ F ₁₄ :K ₂ MnF ₆ and crystal-field parameters (CFPs) are amply discussed. Ultimately, a warm WLED lamp with a high CRI (Ra = 87.5) and a low CCT (3289 K) was successfully created through the combination of a synthesized KSF:Mn ⁴⁺ phosphor and a well-known YAG:Ce ³⁺ phosphor, demonstrating that the developed phosphor is an appealing red component for high-performance warm white illumination.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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