A preparation method for improving the luminescence moisture stability of cerium-doped Sr3AlO4F phosphor, and its products and applications

Abstract

The present invention discloses a method for improving Sr3AlO4F:Ce 3+ The preparation method of phosphor with luminescence stability under humidity conditions comprises: (1) preparing a phosphor according to Sr3AlO4F:0.5%Ce 3+ The compound raw materials of each element are weighed in a stoichiometric ratio, and then mixed with AlN and NH4F, and then subjected to tableting after grinding and drying; (2) the tableted product is subjected to high-temperature sintering treatment, cooled to room temperature, and then ground into powder. The present invention discloses a method for improving the Sr3AlO4F:Ce 3+ A method for preparing phosphor with moisture stability. The emission spectrum peak of the prepared phosphor is stable at 496nm, and it has excellent luminescence performance and moisture stability. The light-emitting diode prepared by mixing the phosphor with commercial phosphor can solve the "cyan gap" and achieve full-spectrum lighting.

Description

Technical Field

[0001] The present invention relates to the technical field of luminescent materials, in particular to a method for improving Sr3AlO4F:Ce 3+ Preparation method, products and applications of phosphor luminescence moisture stability. Background Art

[0002] Phosphor-converted white light-emitting diodes (pc-WLEDs) offer advantages such as energy efficiency, durability, and low pollution, and have become widely used in our daily lives. However, common pc-WLEDs currently suffer from a "cyan gap," making it difficult to achieve full-spectrum WLED lighting similar to daylight. Furthermore, the blue light used to excite LED chips can affect our health and even disrupt our circadian rhythm. Therefore, the development of new phosphors with high photoluminescence (PL) quantum efficiency, moisture stability, and tunable luminescence properties is crucial for WLED applications.

[0003] Fluoride oxide phosphors have the advantages of low sintering temperature and high quantum efficiency, and have attracted widespread attention. They have been widely used in many cutting-edge fields, such as thermal sensors, solar cell spectrum converter materials, fingerprint detection, solid-state lighting, etc. 3+ Phosphors are gaining increasing attention due to their high quantum efficiency and unique cyan-light emission, and have potential applications in white LED lighting. However, they suffer from a serious problem of poor moisture stability, which limits their application to theoretical rather than practical applications.

[0004] Im et al. (Efficient and Color-Tunable Oxyfluoride Solid Solution Phosphors for Solid-State White Lighting) combined Sr3AlO4F and Sr3SiO5 and synthesized Sr3AlO4F by a high temperature solid phase method. 2.975 Ce 0.025 Al 1-x Si x O 4+x F 1-x Phosphors utilize the strong moisture stability of the Sr3SiO5 matrix to improve the moisture stability of the mixture, but this does not fundamentally improve the moisture stability of Sr3AlO4F. Moreover, as the Sr3SiO5 doping ratio increases, the emission color gradually changes from cyan to yellow-green, which does not solve the "cyan gap" problem. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention discloses a method for improving the3+ A method for preparing phosphor with moisture stability. The emission spectrum peak of the prepared phosphor is stable at 496nm, and it has excellent luminescence performance and moisture stability. The light-emitting diode prepared by mixing the phosphor with commercial phosphor can solve the "cyan gap" and achieve full-spectrum lighting.

[0006] The specific technical solutions are as follows:

[0007] A method to improve Sr3AlO4F:Ce 3+ A method for preparing a phosphor with luminescence moisture stability comprises the following steps:

[0008] (1) Press Sr3AlO4F:0.5%Ce 3+ The compound raw materials of each element are weighed in a stoichiometric ratio, and then mixed with AlN and NH4F, and then pressed into tablets after grinding and drying;

[0009] (2) The tabletted product is subjected to high-temperature sintering treatment, cooled to room temperature, and then ground into powder.

[0010] In step (1):

[0011] AlN and Sr3AlO4F:0.5%Ce 3+ The molar ratio is 0.05 to 0.9.

[0012] The experiment found that adding AlN can significantly improve the Sr3AlO4F:Ce 3+ The moisture stability of the phosphor; and when the molar ratio of the added AlN is as high as 0.9, the emission spectrum peak is still 496nm, and the luminescent color is cyan; but when the AlN content is too high or too low, the luminous intensity of the phosphor decreases, and the moisture stability also decreases, but it is still higher than that of Sr3AlO4F:Ce without AlN. 3+ Moisture stability of phosphor substrates.

[0013] Preferably, AlN and Sr3AlO4F:0.5%Ce 3+ The molar ratio of is 0.05 to 0.3; experiments have found that under this molar ratio, the prepared phosphor not only has high luminous intensity but also has excellent moisture stability.

[0014] More preferably, AlN and Sr3AlO4F:0.5%Ce 3+ The molar ratio of is 0.1. Experiments have found that under this molar ratio, the luminous intensity and moisture stability of the prepared phosphor are both optimal.

[0015] Take Sr3AlO4F:0.5%Ce 3+ The doping amount of NH4F is 0.5 to 5.5 wt% based on the total mass of AlN.

[0016] It has been found through experiments that the addition of the specific flux NH4F in the present invention can ensure that N 3- The doping effect of AlN can achieve the above-mentioned excellent luminescence performance and moisture stability. If no flux is added, or the flux added is other common types in the field, such as MgO, even if the AlN is used at the optimal ratio, the luminescence intensity and moisture stability will be significantly degraded.

[0017] Preferably, Sr3AlO4F:0.5%Ce 3+ Based on the total mass of AlN, the doping amount of NH4F is 0.5 to 2.5 wt%, more preferably 0.5 to 1.5 wt%, and more preferably 1.5 wt%.

[0018] The preparation method of the present invention also involves a key process step: tableting after grinding and drying in step (1) before high-temperature sintering in step (2). Experiments have found that failure to perform tableting, or using excessive or insufficient pressure during tableting, can significantly degrade luminous intensity and moisture stability.

[0019] Preferably, the tableting process has a pressure of 8 to 15 MPa and a holding time of 5 to 15 min; more preferably, the pressure is 10 MPa and the holding time is 10 min.

[0020] In step (2):

[0021] The high-temperature sintering treatment is carried out in a reducing atmosphere at a temperature of 1100-1200° C. for 5-15 hours.

[0022] The reducing atmosphere is selected from a hydrogen atmosphere, or a mixed atmosphere of a hydrogen atmosphere and an inert atmosphere.

[0023] Preferred:

[0024] The high-temperature sintering treatment is carried out in a reducing atmosphere at a sintering temperature of 1150° C. for 10 hours.

[0025] The reducing atmosphere is selected from a mixed atmosphere of 10 mol % hydrogen atmosphere and 90 mol % nitrogen atmosphere.

[0026] The present invention also discloses N-doped 3- Sr3AlO4F:Ce 3+ The phosphor has high luminous intensity, up to 3283477a.u.; excellent luminous stability against moisture. After being placed in a humid environment for 120 hours, the luminous intensity retention rate of the phosphor is high, up to 99%.

[0027] The present invention also discloses a light emitting device, comprising a light source and phosphor;

[0028] The phosphor is prepared by the above method. 3- Sr3AlO4F:Ce 3+ Phosphors also include commercial phosphors.

[0029] After testing, the N-doped 3- Sr3AlO4F:Ce 3+ The light-emitting devices prepared by blending the phosphor with commercial phosphor, such as light-emitting diodes, not only have the advantage of high color rendering index, but also can achieve full-spectrum lighting.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention discloses a method for improving Sr3AlO4F:Ce 3+ The preparation method of phosphor luminescence moisture stability is successfully improved by doping AlN and special flux NH4F in the raw material stage; and combining with a special tableting process before high temperature sintering. 3+ The phosphor's luminescence stability under humidity conditions: The phosphor produced by this invention has an emission spectrum peak that is stable at 496nm and exhibits excellent luminescence performance and humidity stability. Light-emitting diodes produced by mixing it with commercial phosphors can resolve the "cyan gap" and achieve full-spectrum lighting. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the emission spectrum of the phosphor prepared in Example 1;

[0033] Figure 2 The XRD pattern of the phosphor prepared in Example 1;

[0034] Figure 3 A histogram showing the luminous intensity of the phosphor prepared in Example 1 changing with time;

[0035] Figure 4 This is the emission spectrum of the WLED prepared in Example 1;

[0036] Figure 5 This is the emission spectrum of the phosphor prepared in Comparative Example 1;

[0037] Figure 6 This is the XRD pattern of the phosphor prepared in Comparative Example 1;

[0038] Figure 7 A histogram showing the luminous intensity of the phosphor prepared in Comparative Example 1 changing with time;

[0039] Figure 8 This is the emission spectrum of the phosphor prepared in Comparative Example 2;

[0040] Figure 9 A histogram showing the luminous intensity of the phosphor prepared in Comparative Example 2 changing with time;

[0041] Figure 10 This is the emission spectrum of the phosphor prepared in Comparative Example 3;

[0042] Figure 11 A histogram showing the luminous intensity of the phosphor prepared in Comparative Example 3 changing with time;

[0043] Figure 12 This is the emission spectrum of the phosphor prepared in Comparative Example 4;

[0044] Figure 13 A histogram showing the luminous intensity of the phosphor prepared in Comparative Example 4 changing with time;

[0045] Figure 14 This is the emission spectrum of the phosphor prepared in Comparative Example 5;

[0046] Figure 15 A histogram showing the luminous intensity of the phosphor prepared in Comparative Example 5 changing with time;

[0047] Figure 16 This is the emission spectrum of the phosphor prepared in Comparative Example 6;

[0048] Figure 17 The emission spectra of the phosphors prepared in Examples 1 to 6 and Comparative Example 1 are shown respectively;

[0049] Figure 18 The figure is a bar graph showing the luminous intensity of the phosphors prepared in Examples 1 to 6 and Comparative Example 1 as a function of time;

[0050] Figure 19 These are the emission spectra of the phosphors prepared in Examples 1 and 7 to 11, respectively. DETAILED DESCRIPTION

[0051] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0052] Example 1

[0053] Press Sr3AlO4F:0.5%Ce 3+The compound raw materials of each element were weighed in the stoichiometric ratio, 0.7368g of SrCO3, 0.0918g of Al2O3, 0.1256g of SrF2, 0.0017g of CeO2, 0.0082g of AlN (AlN and Sr3AlO4F: 0.5% Ce 3+ The prepared sample was placed in an agate mortar, and the sample was kept at 1150°C in a tube furnace under a reducing atmosphere of 90 mol% N2-10 mol% H2 for 10 h. After cooling naturally to room temperature, the sample was taken out and ground into powder. The phosphor prepared in this embodiment is recorded as Sr3AlO 3.9 N 0.1 F:0.5%Ce 3+ .

[0054] The fluorescent powder prepared in this example was characterized and analyzed using a fluorescence spectrometer. Under the excitation of 410 nm wavelength, the emission spectrum was obtained as shown in FIG. Figure 1 As shown in the figure, it is found that the emission spectrum peak is at 496nm, the luminescent color is cyan, and the luminescent intensity is 3283477a.u.

[0055] The phosphor material prepared in this embodiment was analyzed using an X-ray diffractometer to obtain its X-ray diffraction pattern, as shown in FIG. Figure 2 As shown, the obtained sample has a physical phase that is relatively consistent with the standard card, indicating that the physical phase of the obtained phosphor luminescent material is pure.

[0056] Stability test:

[0057] The phosphor prepared in this example was placed directly in humid air with an average humidity of 66% (the emission spectrum of the phosphor was tested before, and its luminous intensity was 3283477 a.u., which was regarded as 100%). The luminous intensity was measured every 24 hours. After 120 hours, the luminous intensity retention rate was 99%. The specific change trend is as follows: Figure 3 shown.

[0058] Application Examples

[0059] The phosphor prepared in Example 1 and commercial phosphor were used as raw materials to prepare light-emitting diodes. The specific preparation method is as follows:

[0060] According to CaAlSiN3:Eu 2+ :Sr3AlO 3.9 N 0.1 F:0.5%Ce3+ :BAM:Eu 2+ =3:35:10 mass ratio Weigh 0.03g of CaAlSiN3:Eu 2+ , 0.35g of Sr3AlO 3.9 N 0.1 F:0.5%Ce 3+ and 0.10 g of BAM:Eu 2+ After being evenly mixed with 0.5 g of UV curable resin, the mixture was coated on a 405 nm UV LDE chip and cured by UV light to produce a light emitting diode (WLED), which was designated as WLED1.

[0061] After testing, the specific parameters were measured as follows Figure 4 As shown, the color rendering index of WLED1 is Ra=91.1, the color temperature CCT=3366K, and the color coordinates CIE are (0.3497, 0.3573).

[0062] From the figure, it can be found that the light-emitting diode made by adding the phosphor prepared in this embodiment has a high color rendering index and a luminous performance close to that of white light.

[0063] Comparative Example 1

[0064] The preparation process is basically the same as that of Example 1, except that AlN is not added.

[0065] The fluorescent powder prepared in this comparative example was characterized and analyzed using a fluorescence spectrometer, and an emission spectrum was obtained under excitation at a wavelength of 410 nm. Figure 5 As shown, the emission spectrum peak is at 496nm and the luminescence intensity is relatively strong.

[0066] The phosphor prepared in this comparative example was analyzed using an X-ray diffractometer to obtain its X-ray diffraction pattern, as shown in FIG. Figure 6 As shown, the obtained sample has a physical phase that is consistent with the standard card, indicating that the obtained phosphor is a pure phase.

[0067] The stability of the product prepared in this comparative example was tested using the same method as in Example 1 (the emission spectrum of the phosphor was tested before, and its luminous intensity was 1638406 a.u., which was regarded as 100%). The luminous intensity was measured every 24 hours, and the luminous intensity retention rate was 35% after 120 hours. The specific change trend is as follows: Figure 7 shown.

[0068] contrast Figure 3 and Figure 7 From the luminous intensity retention rate, it can be seen that the moisture stability of the phosphor prepared in this embodiment is much higher than that of the comparative example 1.

[0069] Comparative Example 2

[0070] The preparation process is basically the same as that of Example 1, except that the flux NH4F is not added. The luminescent material obtained in this comparative example is characterized and analyzed using a fluorescence spectrometer. Under the excitation of a wavelength of 410 nm, an emission spectrum is obtained, as shown in FIG. Figure 8 As shown, the emission spectrum peak is at 497nm and the luminous intensity is 95794a.u.

[0071] The stability was tested in the same manner as in Example 1. Figure 9 As shown, the luminous intensity retention rate is 40% after 120 hours.

[0072] Comparative Example 3

[0073] The preparation process is basically the same as that of Example 1, except that the added flux is replaced by MgO of the same mass.

[0074] The luminescent material obtained by the experiment was characterized and analyzed using a fluorescence spectrometer, and the emission spectrum was obtained under the excitation of 410nm wavelength, as shown in FIG. Figure 10 As shown, the emission spectrum peak is at 497nm and the luminous intensity is 1098524a.u.

[0075] The stability was tested in the same manner as in Example 1. Figure 11 As shown, the luminous intensity retention rate is 43% after 120 hours.

[0076] Comparative Example 4

[0077] The preparation process is basically the same as that of Example 1, except that no tableting process is performed. That is, all raw materials are ground and dried for 1 hour and then directly placed in an alumina crucible for high-temperature sintering.

[0078] The luminescent material obtained in this comparative example was characterized and analyzed using a fluorescence spectrometer, and an emission spectrum was obtained under excitation at a wavelength of 410 nm. Figure 12 As shown, the emission spectrum peak is at 497nm and the luminous intensity is 1265649a.u.

[0079] The stability was tested in the same manner as in Example 1. Figure 13 As shown, the luminous intensity retention rate is 46% after 120 hours.

[0080] Comparative Example 5

[0081] The preparation process is basically the same as that of Example 1, except that the pressure used in the tableting process is replaced with 5 MPa and the pressure is maintained for 10 minutes.

[0082] The luminescent material obtained in this comparative example was characterized and analyzed using a fluorescence spectrometer, and an emission spectrum was obtained under excitation at a wavelength of 410 nm. Figure 14 As shown, the emission spectrum peak is at 497nm and the luminous intensity is 1648101a.u.

[0083] The stability was tested in the same manner as in Example 1. Figure 15 As shown, the luminous intensity retention rate is 68% after 120 hours.

[0084] Comparative Example 6

[0085] The preparation process is basically the same as that of Example 1, except that the pressure used in the tableting process is replaced with 20 MPa and the pressure is maintained for 10 minutes.

[0086] The luminescent material obtained in this embodiment was characterized and analyzed using a fluorescence spectrometer, and an emission spectrum was obtained under excitation at a wavelength of 410 nm. Figure 16 As shown, the emission spectrum peak is at 497nm, the luminous intensity is only 234a.u., and no subsequent stability test was performed.

[0087] Examples 2 to 6

[0088] The preparation process is basically the same as that of Example 1, except that the molar amount of AlN is replaced. Specifically, AlN is mixed with Sr3AlO4F:0.5%Ce. 3+ The molar ratios were changed to 0.05, 0.3, 0.5, 0.7, and 0.9, respectively.

[0089] The phosphors obtained in Examples 2 to 6 were characterized and analyzed using a fluorescence spectrometer. Under excitation at a wavelength of 410 nm, emission spectra were obtained with AlN ratios of 0 (Comparative Example 1), 0.05 (Example 2), 0.1 (Example 1), 0.3 (Example 3), 0.5 (Example 4), 0.7 (Example 5), and 0.9 (Example 6). Figure 17 The specific luminous intensity data are listed in Table 1 below.

[0090] observe Figure 17 It can be found that, by adopting the preparation process of the present invention, even if N 3- When the doping concentration is increased to 0.9:1, the luminescent color of the prepared phosphor is still cyan.

[0091] Table 1

[0092] serial number Luminous intensity (au) Example 1 3283477 Comparative Example 1 1638406 Example 2 2124839 Example 3 2063219 Example 4 1520908 Example 5 1265649 Example 6 1036951

[0093] Observing the luminous intensity of the phosphors prepared with different AlN ratios in Table 1, it can be found that when AlN and Sr3AlO4F:0.5%Ce 3+When the molar ratio of AlN and Sr3AlO4F:0.5%Ce is 0.05-0.3, the prepared phosphor has a higher luminous intensity; 3+ When the molar ratio is 0.1, the luminescence intensity of the phosphor is the highest.

[0094] The stability of the phosphors prepared in Examples 2 to 6 was tested in the same manner as in Example 1, and the stability of the phosphors prepared in Example 1 and Comparative Example 1 was used for comparison. Figure 18 As shown in the figure, it is found that when AlN and Sr3AlO4F:0.5%Ce 3+ When the molar ratio of AlN to Sr3AlO4F:0.5%Ce is 0.1-0.3, the luminous intensity retention rate of the prepared phosphor is also higher. 3+ When the molar ratio is 0.1, the luminescence intensity retention rate of the phosphor is the highest.

[0095] Examples 7 to 11

[0096] The preparation process is basically the same as that of Example 1, except that the doping amount of NH4F added is replaced with 0.5wt%, 2.5wt%, 3.5wt%, 4.5wt% and 5.5wt% respectively.

[0097] The luminescent materials obtained in Examples 7 to 11 were characterized and analyzed using a fluorescence spectrometer. Under excitation at a wavelength of 410 nm, emission spectra of different NH4F contents were obtained. Figure 19 shown and in Figure 19 The emission spectrum of the NH4F doping amount is 1.5wt%, and the specific luminescence intensity data are listed in Table 2 below.

[0098] Table 2

[0099] serial number Luminous intensity (au) Example 1 3283477 Example 7 2117296 Example 8 1978204 Example 9 1494641 Example 10 1149339 Example 11 1058286

[0100] By comparing the luminescence intensity data in Table 2, it can be found that when the doping amount of NH4F is 0.5-2.5wt%, the prepared phosphor has a higher luminescence intensity; and when the doping amount of NH4F is 1.5wt%, the luminescence intensity of the phosphor is the highest.

[0101] The applicant declares that the present invention illustrates the detailed method of the present invention through the above embodiments, but the present invention is not limited to the above detailed method.

Claims

1. A method to improve Sr3AlO4F:Ce 3+ The method for preparing the moisture-stable luminescence of phosphor is characterized in that: The steps include: (1) Press Sr3AlO4F:0.5%Ce 3+ The compound raw materials of each element are weighed in a stoichiometric ratio, and then mixed with AlN and NH4F, and then pressed into tablets after grinding and drying; The compound raw material is selected from SrCO3, Al2O3, SrF2 and CeO2; AlN and Sr3AlO4F:0.5%Ce 3+ The molar ratio is 0.05~0.9; Take Sr3AlO4F:0.5%Ce 3+ The doping amount of NH4F is 0.5~5.5wt% based on the total mass of AlN; The tableting process has a pressure of 8-15 MPa and a holding time of 5-15 min; (2) The tabletted product is subjected to high-temperature sintering treatment, cooled to room temperature, and then ground into powder.

2. The method for improving Sr3AlO4F:Ce according to claim 1 3+ The method for preparing the moisture-stable luminescence of phosphor is characterized in that: In step (2): The high-temperature sintering treatment is carried out in a reducing atmosphere at a temperature of 1100-1200° C. for 5-15 hours. The reducing atmosphere is selected from a hydrogen atmosphere, or a mixed atmosphere of a hydrogen atmosphere and an inert atmosphere.

3. The method for improving Sr3AlO4F:Ce according to any one of claims 1 to 2 3+ A method for preparing a phosphor with luminescence moisture stability, characterized by: AlN and Sr3AlO4F:0.5%Ce 3+ The molar ratio is 0.05~0.3 Take Sr3AlO4F:0.5%Ce 3+ The doping amount of NH4F is 0.5~2.5wt% based on the total mass of AlN.

4. The method for improving Sr3AlO4F:Ce according to claim 3 3+ A method for preparing a phosphor with luminescence moisture stability, characterized by: AlN and Sr3AlO4F:0.5%Ce 3+ The molar ratio is 0.1; Take Sr3AlO4F:0.5%Ce 3+ The doping amount of NH4F is 1.5 wt% based on the total mass of AlN.

5. The method for improving Sr3AlO4F:Ce according to claim 3 3+ A method for preparing a phosphor with luminescence moisture stability, characterized by: The tableting process was performed with a pressure of 10 MPa and a holding time of 10 min.

6. The method for improving Sr3AlO4F:Ce according to claim 3 3+ A method for preparing a phosphor with luminescence moisture stability, characterized by: The high-temperature sintering treatment is carried out in a reducing atmosphere at a sintering temperature of 1150° C. for 10 hours. The reducing atmosphere is selected from a mixed atmosphere of 10 mol % hydrogen atmosphere and 90 mol % nitrogen atmosphere.

7. A N-doped cellulose prepared by the method according to any one of claims 1 to 6 3- Sr3AlO4F:Ce 3+ Phosphor.

8. A light-emitting device comprising a light source and phosphor, characterized in that: The phosphor comprises the N-doped 3- Sr3AlO4F:Ce 3+ Phosphor.

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