Small-particle-size narrow-band green fluorescent powder, preparation method and application thereof

Abstract

The application belongs to the technical field of green fluorescent powder, and provides small-particle-size narrow-band green fluorescent powder, a preparation method and application thereof.The preparation method comprises the following steps: mixing MgO, MnCO3, an HNO3 solution, Al(NO3)3.9H2O and water;dropping the metal ion mixed solution into an NH4HCO3 solution; and sequentially performing precipitation, ultrasonic treatment, aging, centrifugation and drying on the mixed solution to obtain fluffy precursor powder; mixing AlN powder and the fluffy precursor powder, and then sequentially performing calcination and grinding to obtain the small-particle-size narrow-band green fluorescent powder.The small-particle-size narrow-band green fluorescent powder is prepared by the co-precipitation-high-temperature solid-phase method, the synthesis condition is simple, the prepared fluorescent powder has high crystallinity, high luminous intensity, high luminous efficiency, stable physical and chemical properties, small particle size and narrow half-peak width, and can be applied to Micro / Mini-LED devices.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of green phosphor, and particularly relates to a small-particle-size narrow-band green phosphor and a preparation method and application thereof. BACKGROUND

[0002] With the development of economic society, consumers begin to seek a more abundant material life while ensuring their own needs. In terms of display technology, Micro / Mini-LED backlight display devices have the advantages of high luminous efficiency, high color saturation, high contrast, self-luminous, low energy consumption, long service life and the like, and therefore are widely concerned by the academic and industrial circles. Therefore, at present, people are committed to developing narrow-band emitting red and green phosphors.

[0003] The currently commercially available red phosphor K2SiF6:Mn 4+ has begun to be used for the development of Micro / Mini-LED display devices due to its excellent luminescent performance, but K2SiF6:Mn 4+ has the problems of narrow full width at half maximum (FWHM) and low quantum efficiency. In addition, the preparation process needs to use toxic chemicals such as HF, which limits its development to a certain extent. The commercially available green phosphor β-SiAlON:Eu 2+ has a harsh preparation condition and a relatively wide FWHM, which limits its application in Micro / Mini-LED backlight display. The method for preparing inorganic solid luminescent materials in the prior art is mainly high-temperature solid-phase method. Although the high-temperature solid-phase method is easy to operate and suitable for large-scale production, the sample prepared by the high-temperature solid-phase method has uneven distribution of doped ions, and the obtained single luminescent particles are generally 10-20 microns, which cannot match the Micro / Mini-LED chip.

[0004] Therefore, it is of great significance to research a preparation method for simply and efficiently producing a narrow-band green phosphor for Micro / Mini-LED. SUMMARY

[0005] The present application aims at providing a small-particle-size narrow-band green phosphor and a preparation method and application thereof to overcome the deficiencies of the prior art.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions.

[0007] The present application provides a preparation method of a small-particle-size narrow-band green phosphor, comprising the following steps:

[0008] 1) mixing MgO, MnCO3, an HNO3 solution, Al(NO3)3·9H2O and water to obtain a metal ion mixed solution;

[0009] 2) drop the mixed solution of metal ions into the NH4HCO3 solution, sequentially carry out precipitation, ultrasonic, aging, centrifugation and drying on the mixed solution to obtain fluffy powder of the precursor;

[0010] 3) sequentially carry out calcination and grinding on the mixture of the AlN powder and the fluffy powder of the precursor to obtain small-particle-size narrow-band green fluorescent powder.

[0011] Preferably, the molar ratio of Al(NO3)3·9H2O, MgO, MnCO3 and AlN is 2.3-x-y:x:y:0.52-0.57, wherein 0.01≤x≤0.10 and 0.01≤y≤0.15.

[0012] Preferably, the molar volume ratio of MgO, the HNO3 solution and water is 0.01-0.1 mol:0.4-0.6 L:8-12 L; and the molar ratio of MgO and NH4HCO3 is 0.01-0.1:11.5-13.5.

[0013] Preferably, the mass fraction of the HNO3 solution in step 1) is 62-68%, and the concentration of the NH4HCO3 solution in step 2) is 1-2 mol / L.

[0014] Preferably, the temperature of the mixing in step 1) is 25-35℃, and the rotating speed of the mixing is 400-500 r / min.

[0015] Preferably, in the process of the precipitation in step 2), the pH value of the mixed solution is 8-10; the ultrasonic time is 20-40 min, and the aging time is 1-3 h.

[0016] Preferably, the rotating speed of the centrifugation in step 2) is 5500-6500 r / min, and the centrifugation time is 2-4 min; the drying temperature is 50-70℃, and the drying time is 20-24 h.

[0017] Preferably, the calcination temperature in step 3) is 1650-1800℃, the calcination time is 2-4 h, the calcination is carried out under a nitrogen atmosphere, and the pressure of the nitrogen is 0.2-0.6 MPa.

[0018] The application further provides the small-particle-size narrow-band green fluorescent powder prepared by the preparation method.

[0019] The application further provides the application of the small-particle-size narrow-band green fluorescent powder in Micro / Mini-LED devices.

[0020] The application has the following beneficial effects:

[0021] 1) The present application prepares small particle size narrow-band green fluorescent powder by co-precipitation-high temperature solid phase method, the synthesis condition is simple, the prepared fluorescent powder has high crystallinity, high luminous intensity, high luminous efficiency, stable physical and chemical properties, small particle size and narrow half peak width, and can be applied to Micro / Mini-LED devices.

[0022] 2) The small particle size narrow-band green fluorescent powder of the present application is a near-ultraviolet and blue light excited sub-micron scale fluorescent powder gamma-AlON:xMn,yMg, wherein 0.01<=x<=0.10, 0.01<=y<=0.15. The average particle size of the small particle size narrow-band green fluorescent powder is 1.21 microns, 90% of the particle size is distributed in 0.6-1.8 microns, the green fluorescent powder emission peak is located at 519 nm, and the half peak width is 49 nm, which can be well matched with a blue light chip. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 XRD patterns and standard patterns of the narrow-band green fluorescent powder prepared for Example 1 and Comparative Example 1;

[0024] Figure 2 Excitation spectra of the narrow-band green fluorescent powder prepared for Example 1 and Comparative Example 1;

[0025] Figure 3 Emission spectra of the narrow-band green fluorescent powder prepared for Example 1 and Comparative Example 1;

[0026] Figure 4 SEM image of the narrow-band green fluorescent powder prepared for Example 1;

[0027] Figure 5 Particle size distribution graph of the narrow-band green fluorescent powder prepared for Example 1;

[0028] Figure 6 Comparison graph of the emission spectra of the narrow-band green fluorescent powder prepared for Example 1 and Comparative Example 1 with temperature change. DETAILED DESCRIPTION

[0029] The present application provides a preparation method of small particle size narrow-band green fluorescent powder, comprising the following steps:

[0030] 1) Mixing MgO, MnCO3, HNO3 solution, Al(NO3)3·9H2O and water to obtain a metal ion mixed solution;

[0031] 2) Adding the metal ion mixed solution dropwise into the NH4HCO3 solution, and sequentially performing precipitation, ultrasonic, aging, centrifugation and drying on the mixed solution to obtain fluffy precursor powder;

[0032] 3) After mixing the AlN powder and the precursor fluffy powder, calcination and grinding are sequentially performed to obtain the small-particle-size narrow-band green fluorescent powder.

[0033] In the present application, the molar ratio of Al(NO3)3·9H2O, MgO, MnCO3 and AlN is preferably 2.3-x-y:x:y:0.52-0.57, wherein 0.01≤x≤0.10, 0.01≤y≤0.15, further preferably 0.03≤x≤0.08, 0.03≤y≤0.12, more preferably 0.05≤x≤0.07, 0.05≤y≤0.10; and the molar ratio of Al(NO3)3·9H2O, MgO, MnCO3 and AlN is further preferably 2.3-x-y:x:y:0.55.

[0034] In the present application, the molar volume ratio of MgO, HNO3 solution and water is preferably 0.01-0.1 mol:0.4-0.6 L:8-12 L, further preferably 0.03-0.08 mol:0.45-0.55 L:9-11 L, more preferably 0.05-0.07 mol:0.5 L:10 L; and the molar ratio of MgO and NH4HCO3 is preferably 0.01-0.1:11.5-13.5, further preferably 0.03-0.08:12-13, more preferably 0.05-0.07:12.5.

[0035] In the present application, the water is preferably deionized water.

[0036] In the present application, the mass fraction of the HNO3 solution in step 1) is preferably 62-68%, further preferably 64-67%, more preferably 65-66%; and the concentration of the NH4HCO3 solution in step 2) is preferably 1-2 mol / L, further preferably 1.25-1.75 mol / L, more preferably 1.4-1.5 mol / L.

[0037] In the present application, the NH4HCO3 solution is preferably obtained by mixing NH4HCO3 and deionized water, and the mixing temperature is preferably 25-35℃, further preferably 27-32℃, more preferably 29-30℃, and the mixing rate is preferably 400-500 r / min, further preferably 420-480 r / min, more preferably 440-450 r / min.

[0038] In the present application, the mixing temperature in step 1) is preferably 25-35℃, further preferably 27-32℃, more preferably 29-30℃, and the mixing speed is preferably 400-500 r / min, further preferably 420-480 r / min, more preferably 440-450 r / min.

[0039] In the precipitation process of step 2), the pH value of the mixed solution is preferably 8-10, further preferably 8.5-9.5, and more preferably 9; preferably, the pH value of the mixed solution is adjusted by using ammonia water.

[0040] In the present application, the ultrasonic time of step 2) is preferably 20-40 min, further preferably 25-35 min, and more preferably 30 min; the aging time is preferably 1-3 h, further preferably 1.5-2.5 h, and more preferably 2 h.

[0041] In the present application, the centrifugal speed of step 2) is preferably 5500-6500 r / min, further preferably 5800-6200 r / min, and more preferably 5900-6000 r / min, and the centrifugal time is preferably 2-4 min, further preferably 2.5-3.5 min, and more preferably 3 min.

[0042] In the present application, after centrifugation, the supernatant is removed, and the precipitate is washed with anhydrous ethanol and then dried.

[0043] In the present application, the drying temperature of step 2) is preferably 50-70℃, further preferably 55-65℃, and more preferably 58-60℃; the drying time is preferably 20-24 h, further preferably 21-23 h, and more preferably 22 h.

[0044] In the present application, the precursor fluffy powder is brown.

[0045] In the present application, the calcination temperature of step 3) is preferably 1650-1800℃, further preferably 1680-1760℃, and more preferably 1700-1750℃; the calcination time is preferably 2-4 h, further preferably 2.5-3.5 h, and more preferably 3 h; the calcination is preferably carried out in a nitrogen atmosphere, and the nitrogen pressure is preferably 0.2-0.6 MPa, further preferably 0.3-0.5 MPa, and more preferably 0.5 MPa.

[0046] The present application also provides a small-particle-size narrow-band green fluorescent powder prepared by the preparation method, and the chemical formula of the small-particle-size narrow-band green fluorescent powder is γ-AlON:xMn,yMg, wherein 0.01≤x≤0.10 and 0.01≤y≤0.15.

[0047] In the present application, the average particle size of the small-particle-size narrow-band green fluorescent powder is preferably 1.21 μm, and the 90% particle size of the small-particle-size narrow-band green fluorescent powder is preferably 0.6-1.8 μm, further preferably 0.9-1.5 μm.

[0048] The small-particle-size narrow-band green fluorescent powder provided by the application is a micron-sized nitride oxide fluorescent powder, which can be excited by near-ultraviolet light and blue light and has a maximum emission peak in the wavelength range of 510-550 nm; the small-particle-size narrow-band green fluorescent powder has good dispersibility and can ensure good brightness.

[0049] The application also provides application of the small-particle-size narrow-band green fluorescent powder in a Micro / Mini-LED device.

[0050] The technical solutions provided by the application will be described in detail below in combination with embodiments, but they should not be understood as limitations on the protection scope of the application.

[0051] Example 1

[0052] 0.0345g MnCO3 and 0.04g MgO were dissolved in 5mL of a 65% mass fraction HNO3 solution to obtain a first mixed solution; the first mixed solution, 8.1375g Al(NO3)3·9H2O and 100mL of deionized water were mixed under the condition that the temperature was 25℃ and the rotation speed was 500r / min to obtain a metal ion mixed solution. 10g NH4HCO3 and deionized water were mixed under the condition that the temperature was 25℃ and the rotation speed was 500r / min to obtain a 1.25mol / L NH4HCO3 solution.

[0053] After the metal ion mixed solution was added dropwise to the NH4HCO3 solution, 25% ammonia water was used to adjust the pH value of the system to 9, and then ultrasonic treatment (power: 120W) was sequentially performed for 30min, aging was performed for 1h, centrifugation was performed in a centrifuge with a rotation speed of 6000r / min for 3min, then the supernatant was discarded, the precipitate was washed twice with anhydrous ethanol, and then drying was performed in an oven at a temperature of 60℃ for 22h to obtain fluffy precursor powder. After the fluffy precursor powder was mixed with 0.2255g AlN powder and transferred to a boron nitride crucible, calcination was performed at 1700℃ and under a nitrogen pressure of 0.5MPa for 3h, and then cooling and grinding were performed to obtain γ-AlON:0.03Mn 2+ , 0.10Mg 2+ narrow-band green fluorescent powder.

[0054] Example 2

[0055] 0.0345g MnCO3 and 8.1375g Al(NO3)3·9H2O in Example 1 were changed to 0.0575g MnCO3 and 8.0625g Al(NO3)3·9H2O, and other conditions were the same as in Example 1 to obtain γ-AlON:0.05Mn 2+ , 0.10Mg 2+ narrow-band green fluorescent powder.

[0056] Example 3

[0057] Example 1 was changed to 0.0805 g MnCO3 and 7.9875 g Al(NO3)3·9H2O, and other conditions were the same as Example 1 to obtain γ-AlON: 0.07Mn 2+ , 0.10Mg 2+ Narrow-band green fluorescent powder.

[0058] Example 4

[0059] 0.092 g MnCO3 and 0.02 g MgO were dissolved in 4.5 mL of a 64% mass fraction HNO3 solution to obtain a first mixed solution; the first mixed solution, 8.1375 g Al(NO3)3·9H2O and 90 mL of deionized water were mixed under the condition of a temperature of 30°C and a rotation speed of 420 r / min to obtain a metal ion mixed solution. 10.5 g of NH4HCO3 and deionized water were mixed under the condition of a temperature of 30°C and a rotation speed of 420 r / min to obtain a 1.5 mol / L NH4HCO3 solution.

[0060] After the metal ion mixed solution was added dropwise to the NH4HCO3 solution, 25% ammonia water was used to adjust the pH value of the system to 8.5, and then ultrasonic treatment (power of 120 W) was sequentially performed for 25 min, aging was performed for 2 h, centrifugation was performed in a centrifuge at a rotation speed of 5500 r / min for 2 min, then the supernatant was discarded, the precipitate was washed twice with anhydrous ethanol, and then drying was performed in an oven at a temperature of 55°C for 23 h to obtain fluffy precursor powder. After 0.2255 g of AlN powder was mixed with the fluffy precursor powder and then transferred to a boron nitride crucible, calcination was performed at 1650°C and under a nitrogen pressure of 0.4 MPa for 4 h, and then cooling and grinding were performed to obtain γ-AlON: 0.08Mn 2+ , 0.05Mg 2+ Narrow-band green fluorescent powder.

[0061] Example 5

[0062] 0.1495 g MnCO3 and 0.008 g MgO were dissolved in 5.5 mL of a 67% mass fraction HNO3 solution to obtain a first mixed solution; the first mixed solution, 8.0625 g Al(NO3)3·9H2O and 110 mL of deionized water were mixed under the condition of a temperature of 32°C and a rotation speed of 450 r / min to obtain a metal ion mixed solution. 9.5 g of NH4HCO3 and deionized water were mixed under the condition of a temperature of 32°C and a rotation speed of 450 r / min to obtain a 1.4 mol / L NH4HCO3 solution.

[0063] After the metal ion mixed solution was added to the NH4HCO3 solution, the pH value of the system was adjusted to 9.5 using ammonia water with a mass concentration of 25%, and then sequentially ultrasonic treatment (power of 120 W) was performed for 35 min, aging for 1 h, centrifugation in a centrifuge with a rotation speed of 6500 r / min for 4 min, and then the supernatant was discarded, the precipitate was washed twice with anhydrous ethanol, and then dried in an oven at a temperature of 65℃ for 20 h to obtain fluffy precursor powder. After 0.2255 g of AlN powder was mixed with the fluffy precursor powder and transferred to a boron nitride crucible, calcination was performed at 1750℃ under a nitrogen pressure of 0.6 MPa for 2 h, and then cooling and grinding were performed to obtain γ-AlON: 0.13Mn 2+ , 0.02Mg 2+ narrow-band green fluorescent powder.

[0064] Comparative Example 1

[0065] After 0.0805 g of MnCO3, 0.2255 g of AlN, 1.1118 g of Al2O3, and 0.04 g of MgO powder were uniformly mixed and transferred to a boron nitride crucible, calcination was performed at 1800℃ under a nitrogen pressure of 0.5 MPa for 4 h, and then cooling and grinding were performed to obtain γ-AlON: 0.07Mn 2+ , 0.10Mg 2+ narrow-band green fluorescent powder.

[0066] The XRD patterns of the narrow-band green fluorescent powders prepared in Example 1 and Comparative Example 1 and standard patterns are shown in Figure 1 . As can be seen from Figure 1 , all the diffraction peaks correspond to the standard data card one by one, and no impurity peaks are observed. The results show that single-phase samples are successfully prepared by the two methods.

[0067] The excitation spectrum of the narrow-band green fluorescent powder prepared in Example 1 and Comparative Example 1 is shown in Figure 2 , and the emission spectrum of the narrow-band green fluorescent powder prepared in Example 1 and Comparative Example 1 is shown in Figure 3 . As can be seen from the figures, under the excitation of 445 nm, the emission spectrum of the fluorescent powder is 480-580 nm, indicating that the fluorescent powder prepared in Example 1 emits green light. The half-width of the emission spectrum is 49 nm, indicating that the fluorescent powder exhibits narrow-band green emission. Under the same excitation wavelength, the emission peak of the green fluorescent powder of Example 1 is at 519 nm, and the luminescent intensity of the sample obtained in Example 1 is 80% of that of the comparative sample, and the luminescent intensity does not decrease significantly with the decrease of the particle size, and can be effectively excited by a near-ultraviolet chip and a blue chip.

[0068] The SEM image of the narrow-band green fluorescent powder prepared in Example 1 is shown inFigure 4 The particle size distribution of the narrow-band green phosphor prepared in Example 1 is shown in FIG. 2. Figure 5 As shown in FIG. 2, the narrow-band green phosphor prepared in Example 1 has a particle size distribution of 0.6-1.8 μm. Figure 4 It can be seen that the narrow-band green phosphor prepared in Example 1 has an irregular particle morphology and is uniformly dispersed without large-scale agglomeration. Figure 5 It can be seen that the narrow-band green phosphor prepared in Example 1 has a particle size distribution of 0.6-1.8 μm.

[0069] The comparison of the emission spectra of the narrow-band green phosphor prepared in Example 1 and Comparative Example 1 with temperature change is shown in FIG. 3. Figure 6 The luminescent intensity of the phosphor of Example 1 at 150°C is equivalent to that of the phosphor of Comparative Example 1, and at 150°C, the emission intensity is maintained at 80.2% (Example 1) and 80.6% (Comparative Example 1) of that at room temperature, respectively, which has excellent thermal quenching performance.

[0070] The XRD structure refinement of the samples using a general structure analysis system (GSAS) shows that the average atomic displacement parameter Uiso,i of the narrow-band green phosphor prepared in Example 1 and Comparative Example 1 at N sites is 0.00168 and 0.00174, respectively, and Example 1 exhibits a more excellent Debye temperature, indicating that the small-particle-size sample obtained in Example 1 has better structural rigidity, which ensures that the small-particle-size sample can maintain excellent thermal quenching performance. Figure 6 The excellent thermal quenching performance of the small-particle-size narrow-band green phosphor sample prepared in Example 1 is shown, which meets the application requirements of Micro / Mini-LED.

[0071] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a small-particle-size narrow-band green phosphor, characterized in that, It includes the following steps: 1) Mix MgO, MnCO3, HNO3 solution, Al(NO3)3·9H2O and water to obtain a mixed solution of metal ions; 2) The mixed solution of metal ions was added dropwise to the NH4HCO3 solution. The mixture was subjected to precipitation, sonication, aging, centrifugation and drying in sequence to obtain a fluffy precursor powder. 3) After mixing AlN powder and precursor fluffy powder, they are calcined and ground sequentially to obtain small-particle-size narrow-band green phosphor. Step 3) The calcination temperature is 1650~1800℃, the calcination time is 2~4h, and the calcination is carried out in a nitrogen atmosphere with a nitrogen pressure of 0.2~0.6MPa; The chemical formula of the small-particle-size narrow-band green phosphor is γ-AlON:xMn,yMg, where 0.01≤x≤0.10 and 0.01≤y≤0.

15.

2. The preparation method according to claim 1, characterized in that, The molar ratio of Al(NO3)3·9H2O, MgO, MnCO3 and AlN is 2.3-xy:x:y:0.52~0.57, where 0.01≤x≤0.10 and 0.01≤y≤0.

15.

3. The preparation method according to claim 1 or 2, characterized in that, The molar volume ratio of MgO, HNO3 solution and water is 0.01~0.1 mol : 0.4~0.6 L : 8~12 L; the molar ratio of MgO and NH4HCO3 is 0.01~0.1 : 11.5~13.

5.

4. The preparation method according to claim 3, characterized in that, The mass fraction of the HNO3 solution in step 1) is 62-68%, and the concentration of the NH4HCO3 solution in step 2) is 1-2 mol / L.

5. The preparation method according to claim 3, characterized in that, Step 1) The mixing temperature is 25~35℃ and the mixing speed is 400~500r / min.

6. The preparation method according to claim 4 or 5, characterized in that, In step 2), during the precipitation process, the pH value of the mixture is 8-10; the ultrasonic time is 20-40 min; and the aging time is 1-3 h.

7. The preparation method according to claim 6, characterized in that, Step 2) The centrifugation speed is 5500~6500 r / min, and the centrifugation time is 2~4 min; the drying temperature is 50~70℃, and the drying time is 20~24 h.

8. The small-particle-size narrow-band green phosphor prepared by the preparation method according to any one of claims 1 to 7, characterized in that, The chemical formula of the small-particle-size narrow-band green phosphor is γ-AlON:xMn,yMg, where 0.01≤x≤0.10 and 0.01≤y≤0.

15.

9. The application of the small-particle-size narrow-band green phosphor according to claim 8 in Micro / Mini-LED devices.

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