Wet-Resistant Fluoride Red Phosphor and Preparation and Application thereof, and White Light LED Device

Abstract

The present disclosure relates to the field of inorganic non-metallic optoelectronic functional materials, and discloses wet-resistant fluoride red phosphor and preparation and application thereof, and a white light LED device. The fluoride red phosphor is a core-shell structure: the core is Mn.sup.4+ doped fluoride red phosphor, and the chemical structural formula is A.sub.2B.sub.1-xF.sub.6:xMn.sup.4+, herein A is at least one of Li, Na, K, Rb, and Cs, B is at least one of Ti, Si, Ge, Zr, and Sn, and 0?x?0.4; and the shell is a cubic perovskite-type compound, and the chemical structural formula is CMgF.sub.3, herein C is at least one of Li, Na, K, Rb, and Cs. The present disclosure uses CMgF.sub.3 generated as a coating waterproof layer, to form the A.sub.2B.sub.1-xF.sub.6:xMn.sup.4+ core-shell structure of which the surface is coated by CMgF.sub.3, and a wet-resistant problem of the fluoride red phosphor is overcome.

Claims

1. Wet-resistant fluoride red phosphor, wherein the fluoride red phosphor is a core-shell structure: the core is Mn.sup.4+ doped fluoride red phosphor, and the chemical structural formula is A.sub.2B.sub.1-xF.sub.6:xMn.sup.4+, wherein A is at least one of Li, Na, K, Rb, and Cs, B is at least one of Ti, Si, Ge, Zr, and Sn, and 0?x?0.4; and the shell is a cubic perovskite-type compound, and the chemical structural formula is CMgF.sub.3, wherein C is at least one of Li, Na, K, Rb, and Cs.

2. The wet-resistant fluoride red phosphor according to claim 1, wherein the molar ratio of the shell to the core is 0.005-1.0.

3. The wet-resistant fluoride red phosphor according to claim 1, wherein A is at least one of Na and K, B is at least one of Ti and Si, and C is at least one of Na and K.

4. The wet-resistant fluoride red phosphor according to claim 1, wherein the molar ratio of the shell to the core is 0.2, 0.4, 0.6, 0.8, or 1.0.

5. The wet-resistant fluoride red phosphor according to claim 1, wherein the fluoride red phosphor is K.sub.2TiF.sub.6:0.08Mn.sup.4+@KMgF.sub.3, the molar ratio of the shell to the core is 0.2.

6. The wet-resistant fluoride red phosphor according to claim 1, wherein the fluoride red phosphor is K.sub.2SiF.sub.6:0.08Mn.sup.4+@ KMgF.sub.3, the molar ratio of the shell to the core is 0.2.

7. The wet-resistant fluoride red phosphor according to claim 1, wherein the fluoride red phosphor is K.sub.2TiF.sub.6:0.08Mn.sup.4+@NaMgF.sub.3, the molar ratio of the shell to the core is 0.2.

8. A preparation method for the wet-resistant fluoride red phosphor according to claim 1, comprising the following steps: S1: preparing CHF.sub.2 aqueous solution and Mg(NO.sub.3).sub.2 aqueous solution, wherein C is at least one of Li, Na, K, Rb, and Cs; S2: mixing the Mn.sup.4+ doped fluoride red phosphor with the CHF.sub.2 aqueous solution and stirring uniformly, to obtain mixed solution; S3: continuously stirring the mixed solution, dropwise adding the Mg(NO.sub.3).sub.2 aqueous solution into the mixed solution, and after dropwise adding, performing stirring, solid-liquid separating, washing, and drying sequentially, to obtain A.sub.2B.sub.1-xF.sub.6:xMn.sup.4+ core-shell structure fluoride red phosphor of which the surface is coated with CMgF.sub.3; and S4: soaking the A.sub.2B.sub.1-xF.sub.6:xMn.sup.4+ core-shell structure fluoride red phosphor of which the surface is coated with CMgF.sub.3 in water, and performing the solid-liquid separating, washing, and drying, to obtain the wet-resistant fluoride red phosphor.

9. The preparation method for the wet-resistant fluoride red phosphor according to claim 8, wherein, the molar concentration of the CHF.sub.2 aqueous solution is 0.001-10 mol/L; the molar concentration of the Mg(NO.sub.3).sub.2 aqueous solution is 0.001-10 mol/L; the usage amount ratio of the CHF.sub.2 aqueous solution, the Mg(NO.sub.3).sub.2 aqueous solution, and the Mn.sup.4+ doped fluoride red phosphor is (0.01-30) L: (0.01-10) L: 1 g; and the molar amount of the Mn.sup.4+ doped fluoride red phosphor is 0.001-0.40 mol.

10. The preparation method for the wet-resistant fluoride red phosphor according to claim 8, wherein in Step S2, the stirring rate is 50-1200 rpm, and the stirring time is 0-60 min.

11. The preparation method for the wet-resistant fluoride red phosphor according to claim 8, wherein in Step S3, the stirring rate of the continuously stirring is 50-1200 rpm; the stirring rate after the dropwise adding is 50-1200 rpm, and the stirring time is 0-60 min; and the dripping rate is 1-90 seconds/drop.

12. The preparation method for the wet-resistant fluoride red phosphor according to claim 8, wherein in Step S4, the soaking time is 1-60 h.

13. The preparation method for the wet-resistant fluoride red phosphor according to claim 8, wherein in Step S4, the soaking time is 12 h, 24 h, 48 h, or 60 h.

14. The preparation method for the wet-resistant fluoride red phosphor according to claim 8, wherein the preparation method comprising the following steps: S1: preparing KHF.sub.2 aqueous solution and the Mg(NO.sub.3).sub.2 aqueous solution; S2: mixing K.sub.2TiF.sub.6:xMn.sup.4+ with the KHF.sub.2 aqueous solution and stirring for 30 min, to obtain mixed solution; S3: continuously stirring the mixed solution, dropwise adding the Mg(NO.sub.3).sub.2 aqueous solution into the mixed solution, and after dropwise adding, performing stirring for 30 min, performing solid-liquid separating, washing, and performing drying at 70? C., to obtain K.sub.2TiF.sub.6:xMn.sup.4+@KMgF.sub.3; and S4: soaking the K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 in water for 24 h, and performing the solid-liquid separating, washing, and drying, to obtain the wet-resistant fluoride red phosphor.

15. An application of the wet-resistant fluoride red phosphor according to claim 1 used as a red component of a white light LED device serving as a display backlight source and a high color rendering and high contrast lighting source.

16. A white light LED device serving as a display backlight source and a high color rendering and high contrast lighting source, wherein the white light LED device comprises a red component, a green component, and a blue component; and the red component is the wet-resistant fluoride red phosphor according to claim 1.

17. The white light LED device according to claim 16, wherein the green component is a green phosphor with a peak emission wavelength of 520-560 nm and a half peak width of less than 35 nm; and the blue component is an InGaN blue-emitting chip.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0063] By describing exemplary implementation modes of the present disclosure in more detail in combination with drawings, the above and other purposes, features, and advantages of the present disclosure may become more apparent, herein in the exemplary implementation modes of the present disclosure, the same reference signs typically represent the same components.

[0064] FIG. 1 shows a schematic diagram of a preparation process (coating process and recrystallization process) of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor provided in Example 1 of the present disclosure (herein, KTF @KMgF.sub.3 is K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3).

[0065] FIG. 2 shows a photo of K.sub.2TiF.sub.6:Mn.sup.4+ core-shell structure fluoride red phosphor, of which the surface is coated by KMgF.sub.3, soaked in water for 24 h in Example 1 of the present disclosure.

[0066] FIG. 3 shows X-ray diffraction (XRD) patterns of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with different coating ratios in Examples 1-5 of the present disclosure. (Herein, 2 Theta (?) represents an XRD scanning angle, similarly hereinafter.)

[0067] FIG. 4 shows emission spectra of the K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with the different coating ratios after being soaked in water for 24 h in Examples 1-5 of the present disclosure.

[0068] FIG. 5 shows excitation spectra of the K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with the different coating ratios after being soaked in water for 24 h in Examples 1-5 of the present disclosure.

[0069] FIG. 6 shows XRD Patterns of the K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with different soaking times in Example 1, and 6-9 of the present disclosure.

[0070] FIGS. 7 (a), (c), (e), and (g) respectively shows a scanning electron microscope (SEM) image of K.sub.2TiF.sub.6:Mn.sup.4+ uncoated in Example 1, an SEM image of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 in Example 1, an SEM image of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 soaked in water for 24 h in Example 1, and an SEM image of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 soaked in water for 60 h in Example 1.

[0071] FIGS. 7 (b), (d), (f), and (h) respectively shows an energy dispersive spectrometer (EDS) elemental mapping of K.sub.2TiF.sub.6:Mn.sup.4+ uncoated in Example 1, an EDS elemental mapping of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 in Example 1, an EDS elemental mapping of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 soaked in water for 24 h in Example 1, and an EDS elemental mapping of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 soaked in water for 60 h in Example 1. Herein, Mn K?1 represents a characteristic X-ray signal released by excited electrons in an L layer outside an Mn element atomic nucleus transitioning to a K layer, resulting in energy loss, and represents a signal of the Mn element detected by an energy spectrometer; and Mg K?1_2 represents a characteristic X-ray signal released by excited electrons in an L layer outside an Mg element atomic nucleus transitioning to a K layer, resulting in energy loss, and represents a signal of the Mg element detected by the energy spectrometer.

[0072] FIG. 8 shows emission spectra of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with different soaking times in Examples 1, and 6-9.

[0073] FIG. 9 shows excitation spectra of the K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with the different soaking times in Examples 1, and 6-9.

[0074] FIG. 10 shows emission spectra of samples in Examples 10-17 for a first orthogonal experiment.

[0075] FIG. 11 shows emission spectra of samples in Examples 18-25 for the first orthogonal experiment.

[0076] FIG. 12 shows emission spectra of samples in Examples 10-17 for a second orthogonal experiment.

[0077] FIG. 13 shows emission spectra of samples in Examples 18-25 for the second orthogonal experiment.

[0078] FIG. 14 shows XRD Patterns of K.sub.2SiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with different coating ratios in Examples 26-30. (KSF @KMgF.sub.3 is K.sub.2SiF.sub.6:Mn.sup.4+@KMgF.sub.3.)

[0079] FIG. 15 (a)-(f) shows an SEM image of K.sub.2SiF.sub.6:Mn.sup.4+ uncoated in Example 26 ((a)-(b)), an SEM image of K.sub.2SiF.sub.6:Mn.sup.4+@ KMgF.sub.3 in Example 26 ((c)-(d)), and an SEM image of K.sub.2SiF.sub.6:Mn.sup.4+@ KMgF.sub.3 soaked in water for 24 h in Example 26 ((e)-(f)).

[0080] FIG. 16 shows emission spectra of K.sub.2SiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with different coating ratios after being soaked in water for 24 h in Examples 26-30.

[0081] FIG. 17 shows excitation spectra of the K.sub.2SiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with the different coating ratios after being soaked in water for 24 h in Examples 26-30.

[0082] FIG. 18 shows XRD Patterns of K.sub.2TiF.sub.6:Mn.sup.4+@NaMgF.sub.3 phosphor with different coating ratios in Examples 31-35.

[0083] FIG. 19 shows emission spectra of the K.sub.2TiF.sub.6:Mn.sup.4+@NaMgF.sub.3 phosphor with the different coating ratios after being soaked in water for 24 h in Examples 31-35.

[0084] FIG. 20 shows excitation spectra of the K.sub.2TiF.sub.6:Mn.sup.4+@NaMgF.sub.3 phosphor with the different coating ratios after being soaked in water for 24 h in Examples 31-35.

[0085] FIG. 21 (a) shows a spectra of a white light LED device packaged with K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 in Example 1.

[0086] FIG. 21 (b) shows a comparison diagram of a CIE color gamut diagram of the white light LED device in Example 36 and a standard color gamut of the National Television System Committee (the United States). (Herein, NTSC is the standard color gamut of the National Television System Committee.

[0087] FIG. 22 shows a thermal steady-state luminous flux attenuation curve of the white light LED device packaged with K.sub.2TiF.sub.6:Mn.sup.4+ (1), K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 but not soaked in water (2), and K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 after being soaked in water for 24 h (3).

[0088] FIG. 23 shows a thermal steady-state voltage attenuation curve of the white light LED device packaged with K.sub.2TiF.sub.6:Mn.sup.4+ (1), K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 but not soaked in water (2), and K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 after being soaked in water for 24 h (3).

[0089] FIG. 24 shows XRD Patterns of K.sub.2TiF.sub.6:Mn.sup.4+ core-shell structure fluoride red phosphor of which the surface is coated by KMgF.sub.3 in Example 1.

[0090] FIG. 25 shows XRD Patterns of K.sub.2TiF.sub.6:Mn.sup.4+@CaF.sub.2 and K.sub.2TiF.sub.6:Mn.sup.4.

[0091] FIG. 26 shows XRD Patterns of K.sub.2TiF.sub.6:Mn.sup.4+@SrF.sub.2 and K.sub.2TiF.sub.6:Mn.sup.4.

DETAILED DESCRIPTION OF THE INVENTION

[0092] Preferred embodiments of the present disclosure are described in more detail below. Although the preferred embodiments of the present disclosure are described below, it should be understood that the present disclosure may be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and fully convey the scope of the present disclosure to those skilled in the art.

[0093] In the following examples: [0094] Mn.sup.4+ doped fluoride red phosphor was prepared by a means of secondary crystallization assisted with ion exchange; [0095] KHF.sub.2 was purchased from Shanghai SanAiSi Reagent Co., Ltd., and the analytical purity AR is 99%; [0096] Mg(NO.sub.3).sub.2.Math.6H.sub.2O was purchased from Tianjin Damao Chemical Reagent Factory, and the analytical purity AR is 99%; and [0097] anhydrous ethanol was purchased from Sinopharm Group Chemical reagent Co., Ltd, and the analytical purity is 99.7%.

Example 1

[0098] This example provided wet-resistant fluoride red phosphor K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3, and the fluoride red phosphor was a core-shell structure; [0099] the core was K.sub.2TiF.sub.6:Mn.sup.4+, herein the doping concentration of Mn.sup.4+ was x=0.08; and [0100] the shell was KMgF.sub.3.

[0101] The molar ratio of the shell to the core (coating ratio) was 0.2.

[0102] A preparation method for the above wet-resistant fluoride red phosphor included the following steps: [0103] S1: 2 mol/L KHF.sub.2 aqueous solution and 1 mol/L Mg(NO.sub.3).sub.2 aqueous solution were prepared, herein C was at least one of Li, Na, K, Rb, and Cs; [0104] S2: the above K.sub.2TiF.sub.6:Mn.sup.4+ (the molar amount was 0.01 mol) was mixed with 20 mL of the KHF.sub.2 aqueous solution and it was stirred at 400 rpm for 30 min, to obtain mixed solution; [0105] S3: the mixed solution was continuously stirred (400 rpm), the Mg(NO.sub.3).sub.2 aqueous solution was dropwise added into the mixed solution (60 seconds/drop), and after dropwise adding, stirring (400 rpm) for 30 min, suction-filtering, washing with anhydrous ethanol to neutral, and drying (70? C.) were performed sequentially, to obtain K.sub.2TiF.sub.6:Mn.sup.4+ core-shell structure fluoride red phosphor of which the surface was coated with KMgF.sub.3; and [0106] S4: the K.sub.2TiF.sub.6:Mn.sup.4+ core-shell structure fluoride red phosphor of which the surface was coated with KMgF.sub.3 was soaked in water for 24 h (as shown in FIG. 2), and the suction-filtering, washing, and drying (70? C.) were performed, to obtain the wet-resistant fluoride red phosphor.

Examples 2-5

[0107] Wet-resistant fluoride red phosphor was respectively provided in Examples 2-5:

[0108] K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3.

[0109] The difference between Examples 2-5 and Example 1 was that the molar ratios (coating ratio) of shell KMgF.sub.3 to core K.sub.2TiF.sub.6:Mn.sup.4+ in Examples 2-5 were 0.4, 0.6, 0.8, and 1.0 respectively.

[0110] As shown in FIG. 3, XRD Patterns of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with the different coating ratios in Examples 1-5 were presented, and it might be seen that: [0111] the uncoated K.sub.2TiF.sub.6:Mn.sup.4+ corresponded well with the standard PDF #08-0488 of K.sub.2TiF.sub.6.

[0112] After being coated, as shown in a rectangular box in the figure, the characteristic peak of KMgF.sub.3 appeared at diffraction angles of 31.63? and 45.42?, which was consistent with the main peak of the standard PDF #18-1033 of KMgF.sub.3, corresponding to (110) and (200) crystal planes of KMgF.sub.3 respectively. When the molar ratio of K.sub.2TiF.sub.6:Mn.sup.4+ to Mg.sup.2+ was increased from 0.2 to 1.0, the relative peak intensity of the characteristic peak was gradually increased, it was indicated that the coating thickness was increased. However, the main peak of K.sub.2TiF.sub.6:Mn .sup.4+ was not shifted, it was indicated that the generation of KMgF.sub.3 did not affect the basic structure of K.sub.2TiF.sub.6.

[0113] As shown in FIGS. 4 and 5, emission spectra and excitation spectra of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with the different coating ratios after being soaked in water for 24 h in Examples 1-5 were presented, and it might be seen that: as the coating ratio was gradually increased, the luminescence intensity of K.sub.2TiF.sub.6:Mn.sup.4+@ xKMgF.sub.3 phosphor was gradually decreased.

[0114] As shown in Table 1, it was the relative peak intensity and relative integral intensity of the emission spectra in FIG. 4. According to Table 1, when the coating ratio was 0.2, the relative peak intensity was closest to the uncoated K.sub.2TiF.sub.6:Mn.sup.4+, and reaches 99.24%. When the coating ratio was increased to 1.0, the peak intensity was 90.7% of the initial phosphor. Therefore, the surface modification was performed by adopting the scheme provided by the present disclosure, the wet resistance of the phosphor might reach up to 99.24%, almost without reducing the initial luminescent performance of the phosphor.

TABLE-US-00001 TABLE 1 Coating ratio 0 0.2 0.4 0.6 0.8 1.0 Peak intensity 276.2 274.1 273.1 258.1 257.9 250.5 Integral intensity 3023.157 3033.092 3010.387 2862.833 2854.629 2784.897

Examples 6-9

[0115] Wet-resistant fluoride red phosphor was respectively provided in Examples 6-9:

[0116] K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3.

[0117] The difference between Examples 6-9 and Example 1 was that: in Step S4, the K.sub.2TiF.sub.6:Mn .sup.4+ core-shell structure fluoride red phosphor of which the surface was coated with KMgF.sub.3 was soaked in water for 12 h, 36 h, 48 h, and 60 h respectively.

[0118] As shown in FIG. 6, XRD Patterns of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with different soaking times in Examples 1 and 6-9 were presented, and it might be seen that: the relative peak intensity of the characteristic peak at the diffraction angles of 31.63? and 45.42? was not significantly decreased with the increase of the soaking time, it was indicated that the solubility of the KMgF.sub.3 shell layer was very low and was prone to recrystallization.

[0119] As shown in FIGS. 7 (a), (c), (e), and (g), an SEM image of uncoated K.sub.2TiF.sub.6:Mn.sup.4+ in Example 1, an SEM image of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 in Example 1, an SEM image of K.sub.2TiF.sub.6:Mn .sup.4+@KMgF.sub.3 soaked in water for 24 h in Example 1, and an SEM image of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 soaked in water for 60 h in Example 9 were presented respectively, and it might be seen that: [0120] the surface morphology of the uncoated K.sub.2TiF.sub.6:Mn.sup.4+ was regular and flat; [0121] the surface of the K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 that was coated but not soaked in water was irregular; and [0122] the surface of the K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 particles soaked in water for 24 h and 60 h gradually became regular and flat, corresponding to the changes in the surface morphology of the phosphor particles in FIG. 1.

[0123] As shown in FIGS. 7 (b), (d), (f), and (h), an EDS elemental mapping of uncoated K.sub.2TiF.sub.6:Mn .sup.4+ in Example 1, an EDS elemental mapping of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 in Example 1, an EDS elemental mapping of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 soaked in water for 24 h in Example 1, and an EDS elemental mapping of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 soaked in water for 60 h in Example 9 were presented respectively, and it might be seen that: [0124] when it was not coated, there was no a signal of Mg on the surface of the particles; and [0125] after being coated and soaked in water for a certain period of time, there was a signal of Mg presented. Corresponding to FIG. 1, KMgF.sub.3 was grown on the surface of the phosphor particles.

[0126] As shown in FIGS. 8 and 9, emission spectra and excitation spectra of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with different soaking times in Examples 1 and 6-9 were presented, and it might be seen that: as the soaking time was increased, the relative peak intensity and relative integral intensity of the emission spectra were gradually increased, reach the maximum after 24 h of soaking, and then gradually became stabilized without increasing or decreasing. This phenomenon corresponded to the SEM image results of the coated phosphor soaked in water for the different times shown in FIGS. 7 (a), (c), (e), and (g). The surface morphology of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor that was coated but not soaked in water was irregular, which might affect the luminescent performance of the phosphor.

[0127] As shown in Table 2, it was the relative peak intensity and relative integral intensity of the emission spectra in FIG. 8. From Table 2, it might be seen that when the soaking time was 0, its luminescence intensity was the lowest, and after being soaked in water for a certain period of time, the luminescence intensity was gradually increased. This was because the KMgF.sub.3 shell layer on the particle surface, which was difficult to dissolve in water, underwent recrystallization in water, and the surface tended to be regular and flat. Finally, the luminescence intensity of the phosphor was returned to the same level as K.sub.2TiF.sub.6:Mn.sup.4+ phosphor which was not coated but did not have the wet resistance.

TABLE-US-00002 TABLE 2 Time 0 h 12 h 24 h 36 h 48 h 60 h Peak intensity 270.7 281 295.5 297.2 296.4 295 Integral intensity 3009.354 3111.815 3343.793 3299.313 3297.482 3278.201

[0128] As shown in Table 3, the internal quantum efficiency, absorbance, and external quantum efficiency of K.sub.2TiF.sub.6:Mn.sup.4+ uncoated in Example 1, K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 in Example 1, and K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 soaked in water for 24 h in Example 1 were presented. Results showed that the external quantum efficiency of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 coated but not soaked in water was lower than that after being soaked for 24 h, and after being soaked for 24 h, the external quantum efficiency of K.sub.2TiF.sub.6:Mn.sup.4+@ KMgF.sub.3 was returned to 94.8% of the initial uncoated K.sub.2TiF.sub.6:Mn.sup.4+.

TABLE-US-00003 TABLE 3 Internal External quantum quantum Sample efficiency Absorbance efficiency K.sub.2TiF.sub.6:Mn.sup.4+ 86.46% 72.56% 62.73% K.sub.2TiF.sub.6:Mn.sup.4+ @KMgF.sub.3 83.71% 70.81% 59.27% K.sub.2TiF.sub.6:Mn.sup.4+ @KMgF.sub.3- 83.48% 71.22% 59.47% Soaking for 24 h

Examples 10-25

[0129] Wet-resistant fluoride red phosphor was respectively provided in Examples 10-25:

[0130] K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3.

[0131] The difference between Examples 10-25 and Example 1 was that: [0132] the concentration of KHF.sub.2 aqueous solution, the molar amount of K.sub.2TiF.sub.6:Mn.sup.4+ added, the concentration of Mg(NO.sub.3).sub.2 aqueous solution, the dripping rate of the Mg(NO.sub.3).sub.2 aqueous solution, and stirring rate were different, as shown in Table 5.

[0133] Examples 10-25 used Qualitek-4 orthogonal experimental analysis software to design a five-factor four-level orthogonal experiment, as shown in Table 4, the parameters of design range were presented.

TABLE-US-00004 TABLE 4 Factor Level 1 Level 2 Level 3 Level 4 KHF.sub.2 solution concentration 0.1 1 2 4 (mol/L) K.sub.2TiF.sub.6:Mn.sup.4+ molar amount (mol) 0.001 0.005 0.01 0.02 Mg(NO.sub.3).sub.2 solution concentration 0.1 1 2 4 (mol/L) Dripping rate (seconds/drop) 1 30 60 90 Stirring rate (rpm) 50 400 800 1200

[0134] In order to ensure the accuracy of experimental results, two experiments were performed. FIGS. 10 and 11 showed emission spectra of samples 10-17 and 18-25 in the first orthogonal experiment respectively; FIGS. 12 and 13 showed emission spectra of samples 10-17 and 18-25 in the second orthogonal experiment respectively; and the average integral intensity of the results of two orthogonal experiments were shown in Table 5.

[0135] As shown in Table 6, statistical analysis results of the average integral intensity using the Qualitek-4 orthogonal experimental analysis software were specifically as follows: [0136] the optimal solution concentration of KHF.sub.2 was 2 mol/L corresponding to level 3; [0137] the optimal molar amount of K.sub.2TiF.sub.6:Mn.sup.4+ phosphor added was 0.01 mol corresponding to level 3; [0138] the optimal solution concentration of magnesium nitrate was 1 mol/L corresponding to level 2; [0139] the optimal dripping rate was 60 s/drop corresponding to level 3; and [0140] the optimal stirring rate was 50 r/min corresponding to level 1, and the influencing factor of the stirring rate was relatively low in proportion, and the contribution rate was 2.8% (49.868/1780.729). The uniformity of the solution system during the reaction was considered, so the stirring rate of 400 r/min was used for subsequent experiments.

TABLE-US-00005 TABLE 5 KHF.sub.2 KTF molar Mg(NO.sub.3).sub.2 Dripping Stirring Average concentration amount concentration rate rate integral (mol/L) (mol) (mol/L) (s/drop) (rpm) intensity Example 10 0.1 0.001 0.1 1 50 439.867 Example 11 0.1 0.005 1 30 400 442.193 Example 12 0.1 0.01 2 60 800 1540.502 Example 13 0.1 0.02 4 90 1200 494.973 Example 14 1 0.001 1 60 1200 1634.5645 Example 15 1 0.005 0.1 90 800 1879.858 Example 16 1 0.01 4 1 400 2010.5015 Example 17 1 0.02 2 30 50 2204.42 Example 18 2 0.001 2 90 400 2216.7205 Example 19 2 0.005 4 60 50 2206.5955 Example 20 2 0.01 0.1 30 1200 3137.917 Example 21 2 0.02 1 1 800 3378.0465 Example 22 4 0.001 4 30 800 600.322 Example 23 4 0.005 2 1 1200 2210.838 Example 24 4 0.01 1 90 50 2856.107 Example 25 4 0.02 0.1 60 400 2776.64

TABLE-US-00006 TABLE 6 Level Contribution Factor description Level value KHF.sub.2 solution concentration (mol/L) 2 3 857.941 KTF molar amount (mol) 0.01 3 509.377 Mg(NO.sub.3).sub.2 solution concentration 1 2 200.848 (mol/L) Dripping rate (seconds/drop) 60 3 162.696 Stirring rate (rpm) 50 1 49.868

Example 26

[0141] Wet-resistant fluoride red phosphor K.sub.2SiF.sub.6:Mn.sup.4+@KMgF.sub.3 was provided in this example.

[0142] The fluoride red phosphor was a core-shell structure; [0143] the core was K.sub.2SiF.sub.6:Mn.sup.4+, herein the doping concentration of Mn.sup.4+ was x=0.08; and [0144] the shell was KMgF.sub.3.

[0145] The molar ratio (coating ratio) of the shell to the core was 0.2.

[0146] A preparation method for the wet-resistant fluoride red phosphor in this example was the same as that in Example 1.

Examples 27-30

[0147] Wet-resistant fluoride red phosphor was respectively provided in Examples 27-30:

[0148] K.sub.2SiF.sub.6:Mn.sup.4+@KMgF.sub.3.

[0149] The difference between Examples 27-30 and Example 26 was that the molar ratios (coating ratio) of the shell KMgF.sub.3 to core K.sub.2SiF.sub.6:Mn.sup.4+ in Examples 27-30 was 0.4, 0.6, 0.8, and 1.0 respectively.

[0150] As shown in FIG. 14, XRD Patterns of K.sub.2SiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with different coating ratios in Examples 26-30 were presented, and it might be seen that: [0151] the uncoated K.sub.2SiF.sub.6:Mn.sup.4+ corresponded well with the standard PDF #75-0694 of K.sub.2SiF.sub.6.

[0152] After being coated, as shown in a rectangular box in the figure, the characteristic peak of KMgF.sub.3 appeared at diffraction angles of 31.63? and 45.42?, which was consistent with the main peak of the standard PDF #18-1033 of KMgF.sub.3, corresponding to (110) and (200) crystal planes of KMgF.sub.3 respectively. When the molar ratio of K.sub.2SiF.sub.6:Mn.sup.4+ to Mg.sup.2+ was increased from 0.2 to 1.0, the relative peak intensity of the characteristic peak was gradually increased, it was indicated that the coating thickness was increased. However, the main peak of K.sub.2SiF.sub.6:Mn .sup.4+ was not shifted, it was indicated that the generation of KMgF.sub.3 did not affect the basic structure of K.sub.2SiF.sub.6.

[0153] As shown in FIG. 15 (a)-(f), an SEM image of K.sub.2SiF.sub.6:Mn.sup.4+ uncoated in Example 26 ((a)-(b)), an SEM image of K.sub.2SiF.sub.6:Mn.sup.4+@KMgF.sub.3 in Example 26 ((c)-(d)), and an SEM image of K.sub.2SiF.sub.6:Mn.sup.4+@KMgF.sub.3 soaked in water for 24 h in Example 26 ((e)-(f)) were presented respectively, and it might be seen that: [0154] in FIG. 15 (a)-(b), the surface of the uncoated K.sub.2SiF.sub.6:Mn.sup.4+ was relatively smooth, and the phosphor particles were uniformly square in shape; [0155] in FIG. 15 (c)-(d), the surface of K.sub.2SiF.sub.6:Mn.sup.4+@KMgF.sub.3 was coated with an uneven shell layer, the particle surface was rough, but it might still be seen that the matrix of the phosphor particles was square; and [0156] in FIG. 15 (e)-(f), the rough surface of K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 soaked in water for 24 h in Example 26 became relatively smooth.

[0157] As shown in FIGS. 16 and 17, emission spectra and excitation spectra of K.sub.2SiF.sub.6:Mn.sup.4+@KMgF.sub.3 phosphor with different coating ratios after being soaked in water for 24 h in Examples 26-30 were presented, and it might be seen that the decrease in luminescence intensity of the phosphor after being coated and soaked in water for 24 h was not significant compared to the untreated phosphor.

[0158] As shown in Table 7, they were the relative peak intensity and relative integral intensity of the emission spectra in FIG. 16. From Table 7, it might be seen that the results were consistent with the changes in luminescence intensity of K.sub.2TiF.sub.6:Mn.sup.4+ after being coated. As the coating ratio was increased, the luminescence intensity was gradually decreased. When x=0.2, wherein x was the molar ration of shell to core, the emission spectra integral intensity of K.sub.2SiF.sub.6:Mn.sup.4+@0.2KMgF.sub.3 after being soaked in water for 24 h was 96.15% of the initial K.sub.2SiF.sub.6:Mn.sup.4+. When x=1.0, namely the coating ratio was largest and the shell layer was thickest, the emission spectra integral intensity of K.sub.2SiF.sub.6:Mn.sup.4+@1.0KMgF.sub.3 after being soaked in water for 24 h was 87.38% of the initial K.sub.2SiF.sub.6:Mn.sup.4+.

TABLE-US-00007 TABLE 7 Coating ratio 0 0.2 0.4 0.6 0.8 1.0 Peak intensity 427.4 411.5 404.5 388.1 387.3 376 Integral intensity 4045.89 3890.19 3832.42 3668.92 3669.51 3535.22

Example 31

[0159] Wet-resistant fluoride red phosphor K.sub.2TiF.sub.6:Mn.sup.4+@NaMgF.sub.3 was provided in this example.

[0160] The fluoride red phosphor was a core-shell structure; [0161] the core was K.sub.2TiF.sub.6:Mn.sup.4+, which was the same as Example 1; and [0162] the shell was NaMgF.sub.3.

[0163] The molar ratio (coating ratio) of the shell to the core was 0.2.

[0164] The preparation method for the wet-resistant fluoride red phosphor in this example was the same as that in Example 1.

Examples 32-35

[0165] Wet-resistant fluoride red phosphor was respectively provided in Examples 32-35:

[0166] K.sub.2TiF.sub.6:Mn.sup.4+@NaMgF.sub.3.

[0167] The difference between Examples 32-35 and Example 31 was that the molar ratios (coating ratio) of the shell NaMgF.sub.3 to the core K.sub.2TiF.sub.6:Mn.sup.4+ in Examples 32-35 were 0.4, 0.6, 0.8, and 1.0 respectively.

[0168] As shown in FIG. 18, XRD Patterns of K.sub.2TiF.sub.6:Mn.sup.4+@NaMgF.sub.3 phosphor with different coating ratios in Examples 31-35 were presented, and it might be seen that: [0169] the diffraction results of K.sub.2TiF.sub.6:Mn.sup.4+@NaMgF.sub.3 corresponded accurately to the K.sub.2TiF.sub.6 standard PDF card, and the NaMgF.sub.3 characteristic peak appeared at the diffraction angle of 47.3?, which corresponded accurately to the strongest peak on its standard PDF card. It was indicated that the coating method successfully synthesizes NaMgF.sub.3 and forms a shell layer.

[0170] As shown in FIGS. 19 and 20, emission spectra and excitation spectra of K.sub.2TiF.sub.6:Mn.sup.4+@NaMgF.sub.3 phosphor with the different coating ratios after being soaked in water for 24 h in Examples 31-35 were presented, and it might be seen that as the coating ratio was increased, the luminescence intensity was gradually decreased. When x=0.2, the integral intensity was 74.3% of the initial K.sub.2TiF.sub.6:Mn.sup.4+, and the waterproof performance was slightly lower than that of the KMgF.sub.3 shell. When x=0.8, the peak intensity was 61.5% of the initial K.sub.2TiF.sub.6:Mn.sup.4+.

[0171] As shown in Table 8, it was the relative peak intensity and relative integral intensity of the emission spectra in FIG. 19.

TABLE-US-00008 TABLE 8 Coating ratio 0 0.2 0.4 0.6 0.8 Peak intensity 353.6 261.4 233.9 231.5 216.1 Integral intensity 3855.41 2864.35 2553.23 2537.74 2370.15

Example 36

[0172] A white light LED device serving as a display backlight source was provided in this example, and the white light LED device included a red component, a green component, and a blue component; [0173] the red component was the wet-resistant fluoride red phosphor in Example 1; [0174] the green component was the ?-SIALON:Eu.sup.2+ green phosphor; and [0175] the blue component was an InGaN blue-emitting chip.

[0176] As shown in FIG. 21 (a), it was a spectra of a white light LED device packaged with K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 in Example 1. As shown in FIG. 21 (b), it was a comparison diagram of a CIE color gamut diagram of the white light LED device in this example and a standard color gamut of the National Television System Committee. As shown in FIGS. 21 (a) and (b), the color gamut of the white light LED device in this example reaches 105.2% NTSC, and the luminous efficiency was 97.55 I m/W, so it was suitable as the display backlight source.

[0177] As shown in FIGS. 22 and 23, it was a thermal steady-state luminous flux attenuation curve and a thermal steady-state voltage attenuation curve of the white light LED device packaged with K.sub.2TiF.sub.6:Mn.sup.4+ (1), K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 but not soaked in water (2), and K.sub.2TiF.sub.6:Mn.sup.4+@KMgF.sub.3 after being soaked in water for 24 h (3), and it might be seen that: the stability of the device 3 was the best under double 85 test conditions (The temperature is 85 degrees Celsius and the humidity is 85 percent), after 360 seconds of testing, the luminous flux was attenuated to 90.55%, the device voltage was 99.13%, and compared to the device 1, the attenuation amplitude of the effect was significantly smaller.

[0178] As shown in Table 9, it was optoelectronic parameters of the devices 1, 2, and 3 under 120 mA current excitation.

TABLE-US-00009 TABLE 9 Luminous Color Luminous Number efficacy (Lm/W) gamut (NTSC) efficiency (%) 1 93.05 105.2% 47.6 2 89.46 105.2% 38.9 3 97.55 105.2% 46.8

Comparative Examples 1-2

[0179] In Comparative examples 1-2, alkaline earth metal nitrate solution, Ca.sup.2+ and Sr.sup.2+, in the same family as Mg was respectively used to replace the Mg(NO.sub.3).sub.2 aqueous solution and dropwise added into the mixed solution for coating treatment, and the other steps were the same as in Example 1. Results were shown in FIGS. 24-26: [0180] the coated phosphor showed distinct characteristic peaks of the shell layer substance at the corresponding diffraction angles.

[0181] It might be seen from FIG. 24 that the XRD Patterns of K.sub.2TiF.sub.6:Mn.sup.4+ core-shell structure fluoride red phosphor of which the surface was coated by KMgF.sub.3 in Example 1 showed the characteristic peak of KMgF.sub.3 at diffraction angles of 31.63? and 45.42?; [0182] it might be seen from FIG. 25 that the characteristic peak of CaF.sub.2 appeared at diffraction angles of 28.27? and 47.00?; and [0183] it might be seen from FIG. 26 that the characteristic peak of SrF.sub.2 appeared at diffraction angles of 26.57? and 44.12?.

[0184] It was indicated that by using the same coating process and using different alkaline earth metal nitrates as the titration solution, only the addition of Mg.sup.2+ nitrate solution might generate KMgF.sub.3.

[0185] Various embodiments of the present disclosure are already described above, and the above description is exemplary, not exhaustive, and is not limited to the embodiments disclosed. Many modifications and changes are apparent to those of ordinary skill in the art, without deviating from the scope and spirit of the embodiments described.