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A novel red-emitting K_2(Ge,Si)F_6:Mn~(4+) phosphor with uniform morphology was synthesized by co-precipitation method. The pure K_2GeF_6 phase with P63 mc space group other than P3m1 space group was affirmed just by incorporation of Si in K_2GeF_6 at room temperature according to XRD characterization. SEM images showed lamellar and octahedron grain morphology for K_2GeF_6:Mn~(4+) and K_2(Ge,Si)F_6:Mn~(4+) phosphors, respectively. It was also found that the photoluminescence excitation(PLE) and photoluminescence(PL) showed slight displacement in K_2GeF_6:Mn~(4+) and K_2(Ge,Si)F_6:Mn~(4+) system. And the zero-phonon line(ZPL) of the PL spectrum of K_2GeF_6:Mn~(4+) with Si showed a strong peak. Meanwhile crystalline field surrounding Mn~(4+) changes could affect the decay time in this fluoride system. The color gamut of the LED devices based on K_2(Ge,Si)F_6:Mn~(4+) and K_2GeF_6:Mn~(4+) 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 K_2(Ge,Si)F_6:Mn~(4+) phosphor are desirable for potential applications as a red phosphor for improving lighting and display quality of conventional white LEDs.
A pure red-emitting K_2 (Ge, Si) F_6: Mn ~ (4 +) phosphor with uniform morphology was synthesized by co-precipitation method. The pure K_2GeF_6 phase with P63 mc space group other than P3m1 space group was affirmed just by incorporation of Si in K_2GeF_6 at room temperature according to XRD characterization. respectively. SEM images showed lamellar and octahedron grain morphology for K_2GeF_6: Mn ~ (4+) and K_2 (Ge, Si) F_6: Mn ~ (4+) phosphors, respectively. also found that the photoluminescence excitation (PLE) and photoluminescence (PL) showed slight displacement in K_2GeF_6: Mn ~ (4+) and K_2 (Ge, Si) F_6: Mn ~ (4+) system. And the zero-phonon line ZPL) of the PL spectrum of K_2GeF_6: Mn ~ (4+) with Si showed a strong peak. When crystalline field surrounding Mn ~ (4+) changes could affect the decay time in this fluoride system. The color gamut of the LED devices based on K_2 (Ge, Si) F_6: Mn ~ (4+) and K_2GeF_6: Mn ~ (4+) reached up to 94.58% NTSC (National Television Standards Committee) and 94.386% NTSC, respectively, tha All these original characteristics in K_2 (Ge, Si) F_6: Mn ~ (4 +) phosphor are desirable for potential applications as a red phosphor for improving lighting and display quality of conventional white LEDs.