Synthesis and photoluminescence properties of octahedral K₂（Ge,Si）F₆:Mn⁴⁺ red phosphor for white LED

金玉明，刘荣辉，陈观通，刘元红，马小乐，邵冷冷，王磊

National Engineering Research Center for Rare Earth Materials,General Research Institute for Nonferrous Metals,and Grirem Advanced Materials Co.,Ltd.

摘 要：A novel red-emitting K₂（Ge,Si）F₆:Mn⁴⁺ phosphor with uniform morphology was synthesized by co-precipitation method. The pure K₂GeF₆ phase with P63 mc space group other than P3m1 space group was affirmed just by incorporation of Si in K₂GeF₆ at room temperature according to XRD characterization. SEM images showed lamellar and octahedron grain morphology for K₂GeF₆:Mn⁴⁺ and K₂（Ge,Si）F₆:Mn⁴⁺ phosphors, respectively. It was also found that the photoluminescence excitation（PLE） and photoluminescence（PL） showed slight displacement in K₂GeF₆:Mn⁴⁺ and K₂（Ge,Si）F₆:Mn⁴⁺ system. And the zero-phonon line（ZPL） of the PL spectrum of K₂GeF₆:Mn⁴⁺ with Si showed a strong peak. Meanwhile crystalline field surrounding Mn⁴⁺ changes could affect the decay time in this fluoride system. The color gamut of the LED devices based on K₂（Ge,Si）F₆:Mn⁴⁺ and K₂GeF₆:Mn⁴⁺ reached up to 94.58% NTSC（National Television Standards Committee） and 94.386% NTSC, respectively, that was much higher than that based on nitride red phosphors. All these original characteristics in K₂（Ge,Si）F₆:Mn⁴⁺ phosphor are desirable for potential applications as a red phosphor for improving lighting and display quality of conventional white LEDs.

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