Near ultraviolet excited silicate matrix blue fluorescent powder for plant illumination and preparation method thereof

Abstract

The invention relates to near ultraviolet excited silicate matrix blue fluorescent powder for plant illumination and a preparation method of the near ultraviolet excited silicate matrix blue fluorescent powder. The chemical formula of the blue fluorescent powder is Ba < 1.3-x > Ca < 0.7 > SiO4: xEu < 2 + >, the preparation method comprises the following steps: adding Ba (NO3) 2, Ca (NO3) 2.4 H2O and Eu (NO3) 3.6 H2O into deionized water to prepare a solution A; adding an ethyl silicate solution mixed with ethanol into a mixed solution of deionized water, ethanol and ammonia water to obtain a suspension B; adding ammonium bicarbonate into the suspension B, and then adding the solution A to obtain a suspension C; and carrying out a reaction on the suspension C at 200-250 DEG C for 4-16 h, carrying out suction filtration, drying to obtain a precursor, adding a fluxing agent, uniformly mixing, carrying out heat treatment at 1100-1300 DEG C in a reducing atmosphere for 2-10 h, cooling and grinding to obtain a final product. The fluorescent powder is the fluorescent powder with the shortest emission wavelength of a silicate matrix at present, and can reach a 450nm blue light wave band.

Description

Technical Field

[0001] This invention relates to phosphors and their preparation methods, particularly to a near-ultraviolet light-excited silicate matrix blue phosphor and its preparation method. Background Technology

[0002] In recent years, blue LED chips have been used to excite YAG:Ce 3+ Yellow phosphors are currently the most widely used commercial solution for achieving white LEDs. This solution is simple to combine, has a mature process, and low manufacturing cost. However, because it only uses one phosphor color, it can only cover the yellow light portion, resulting in a low color rendering index (CRI), which cannot meet the requirements of high-quality lighting applications such as everyday lighting. Moreover, the white light solution with a higher CRI obtained by exciting multiple phosphors with a blue chip still lacks the near-ultraviolet and deep blue light components in the 380-450 nm range compared to sunlight. This limits the application of white LED light sources excited by blue chips in some fields.

[0003] Photosynthesis plays a vital role in energy conversion and maintaining the carbon-oxygen balance in the atmosphere. Chlorophyll is an essential pigment for plants to complete photosynthesis, with both chlorophyll a and chlorophyll having strong absorption peaks in the blue light band. Studies have shown that ultraviolet light can effectively inhibit excessive plant growth and increase nutrient content, thereby improving plant yield. Currently, the mainstream Eu... 2+ Phosphors doped with silicate matrices are synthesized using a high-temperature solid-state method and emit blue or green light after ultraviolet excitation. Therefore, the commercially available approach of exciting various phosphors with blue light chips cannot meet the requirements of plant lighting. Developing phosphors that emit blue light upon near-ultraviolet excitation is of significant research importance for plant lighting and for the preparation of full-spectrum LEDs that are closer to the solar spectrum. Summary of the Invention

[0004] The purpose of this invention is to provide a Ba2O3 light source for near-ultraviolet-excited white LEDs and plant lighting that is simple to manufacture, low in cost, and easy to industrialize. 1.3 Ca 0.7 SiO4:Eu 2+ Blue phosphor and its preparation method.

[0005] The objective of this invention is achieved through the following technical solution: a near-ultraviolet light-excited silicate blue phosphor with the chemical formula Ba. 1.3-x Ca 0.7 SiO4:xEu 2+ , where x is 0.005-0.05, preferably 0.02 or 0.04.

[0006] The silicate blue phosphor of the present invention has an average particle size of 7~8μm and emits 450nm blue light after being excited by ultraviolet light.

[0007] This invention also provides a method for preparing the silicate blue phosphor of this invention, comprising the following steps:

[0008] (1) Select NH4Cl or BaCl2 as fluxing raw material and ball mill it into fine powder;

[0009] (2) Weigh out the required Ba(NO3)2, Ca(NO3)2·4H2O and Eu(NO3)3·6H2O according to the stoichiometric ratio and dissolve them in deionized water to form solution A;

[0010] (3) Weigh out ethyl silicate according to the stoichiometric ratio and dissolve it in anhydrous ethanol to form solution B;

[0011] (4) Mix a certain proportion of deionized water, ethanol and ammonia to prepare a mother liquor;

[0012] (5) Slowly add solution B from step (3) to the mother liquor from step (4) to obtain SiO2 suspension, and then add a certain amount of ammonium bicarbonate as a precipitant to form solution C;

[0013] (6) Slowly add solution A from step (2) to solution C from step (5) to obtain a mixed suspension D;

[0014] (7) The suspension D obtained in step (6) is loaded into a high-pressure reactor, placed in an oven and heated at 200~250℃ for 4-16 hours. After removal, it is filtered and dried to obtain the precursor.

[0015] (8) The precursor obtained in step (7) and the flux described in step (1) are mixed in a ratio of 0.5-8% by mass of the precursor and the flux. The mixture is then heat-treated at 1100-1300℃ for 2-10 hours in a reducing atmosphere. After cooling to room temperature, a blocky crude product is obtained. The final product is obtained by ball milling.

[0016] In further step (4), the volume ratio of deionized water, ethanol and ammonia is 1:1:1.5 to 1:1:3.

[0017] In further step (5), the amount of ammonium bicarbonate added is 1.2-1.5 times the sum of the molar amounts of Ca and Ba.

[0018] Further step (7) involves placing the food in an oven and heating it at 230°C for 16 hours.

[0019] The further reducing atmosphere in step (8) is a mixture of H2 and N2 in a volume ratio of 1:4.

[0020] The present invention also provides an LED lamp comprising the silicate blue phosphor described herein.

[0021] The present invention also provides the application of LED lamps comprising the silicate blue phosphor described herein in plant growth lighting.

[0022] The beneficial effects of this invention are: the near-ultraviolet excited Ba obtained by this invention 1.3 Ca 0.7 SiO4:Eu 2+ This blue phosphor exhibits high luminous efficiency, uniform particle size, and clear crystal surface. Furthermore, it is the first time that this chemical formula has been found to emit blue light, specifically 450nm blue light upon ultraviolet excitation. Its spectral combination has significant practical value in the field of plant lighting. The preparation method provided by this invention is simple, low-cost, and easy for industrial production, producing phosphors with uniform particle size distribution. Attached Figure Description

[0023] Figure 1 This is a scanning electron microscope image of the phosphor obtained according to the method described in Example 1.

[0024] Figure 2 This is a particle size distribution diagram of the phosphor obtained according to the method described in Example 1.

[0025] Figure 3 The excitation and emission spectra of the phosphor obtained according to the method described in Example 2 are compared with those of the phosphors obtained according to the methods described in Comparative Examples 1 and 2.

[0026] Figure 4 The image shows an XRD comparison of the phosphor obtained according to the method described in Example 2 with the phosphor obtained according to the methods described in Comparative Examples 1 and 2. Detailed Implementation

[0027] The following examples are provided to better understand the present invention, but are not intended to limit the invention. Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the experimental materials used in the following examples were purchased from conventional biochemical reagent stores.

[0028] Example 1:

[0029] According to the chemical formula Ba 1.28 Ca 0.7 SiO4: 0.02Eu 2+ Weigh the raw materials separately, and follow these steps:

[0030] BaCl2 was used as a flux and ground into a fine powder. 0.2 g of this powder was weighed and placed in an agate mortar for later use. 2.840 g of Ba(NO3)2, 1.382 g of Ca(NO3)2·4H2O, and 0.037 g of Eu(NO3)3·6H2O were dissolved in 50 mL of deionized water to form solution A. 1.741 g of ethyl silicate was dissolved in 30 mL of anhydrous ethanol to form solution B. 20 mL of deionized water, 20 mL of anhydrous ethanol, and 30 mL of ammonia were mixed to prepare a mother liquor. Solution B was slowly added dropwise to the mother liquor to obtain... A SiO2 suspension was prepared by adding 10 mg of ammonium bicarbonate as a precipitant to form solution C. Solution A was then added dropwise to C to obtain a mixed suspension D. Suspension D was placed in a high-pressure reactor and heated in an oven at 230°C for 16 hours. After removal, it was filtered and dried to obtain a precursor. The precursor was mixed evenly with the previously prepared BaCl2 in a mortar, then placed in a corundum crucible and placed in a furnace. Under a reducing atmosphere of H2 and N2 mixed in a volume ratio of 1:4, it was heat-treated at 1200°C for 8 hours. After cooling, a blocky crude product was obtained. The crude product was ground to obtain BaCl2. 1.28 Ca 0.7 SiO4: 0.02Eu 2+ Sample. The scanning electron microscope image of the sample is shown below. Figure 1 The particle size distribution diagram shown is obtained by scanning tunneling microscope (S4800, Hitachi, Japan) at 5000x magnification. Figure 2 As shown (obtained by a laser particle size analyzer (Zetasizer Nano, Malvern Panaco, Netherlands)).

[0031] Example 2:

[0032] According to the chemical formula Ba 1.26 Ca 0.7 SiO4:0.04Eu 2+ Weigh the raw materials separately, and follow these steps:

[0033] Using NH4Cl as a flux, it was ground into a fine powder, and 0.12 g was weighed and placed in an agate mortar for later use. 3.786 g of Ba(NO3)2, 1.842 g of Ca(NO3)2·4H2O, and 0.05 g of Eu(NO3)3·6H2O were weighed and dissolved in 50 mL of deionized water to form solution A. 2.322 g of ethyl silicate was weighed and dissolved in 30 mL of anhydrous ethanol to form solution B. 20 mL of deionized water, 20 mL of anhydrous ethanol, and 30 mL of ammonia were mixed to prepare a mother liquor. Solution B was slowly added dropwise to the mother liquor to obtain... A SiO2 suspension was prepared by adding 10 mg of ammonium bicarbonate as a precipitant to form solution C. Solution A was then added dropwise to C to obtain a mixed suspension D. Suspension D was placed in a high-pressure reactor and heated in an oven at 230°C for 16 hours. After removal, it was filtered and dried to obtain a precursor. The precursor was mixed evenly with the previously prepared BaCl2 in a mortar, then placed in a corundum crucible and placed in a furnace. Under a reducing atmosphere of H2 and N2 mixed in a volume ratio of 1:4, it was heat-treated at 1200°C for 8 hours. After cooling, a blocky crude product was obtained. The crude product was ground to obtain BaCl2. 1.28 Ca 0.7 SiO4: 0.02Eu 2+ Sample. The XRD pattern of the phosphor in Example 2 is shown below. Figure 4 As shown (obtained by X-ray diffraction (Smartlab9, Rigaku, Japan) test).

[0034] Comparison Group Example 1:

[0035] Samples were prepared using traditional solid-phase methods, according to the chemical formula Ba. 1.28 Ca 0.7 SiO4: 0.02Eu 2+ Weigh the raw materials separately, and follow these steps:

[0036] BaCl2 was used as a flux and ground into a fine powder. 0.206 g of this powder was weighed and placed in an agate mortar. Then, 3.368 g of barium carbonate, 0.934 g of calcium carbonate, 0.801 g of silicon dioxide, and 0.047 g of europium oxide were added and ground thoroughly until homogeneous. The powder was then placed in a corundum crucible and heat-treated at 1200°C for 8 hours in a reducing atmosphere of H2 and N2 mixed in a 1:4 volume ratio. After cooling, a bulk crude product was obtained. This crude product was then ground to obtain BaCl2 obtained by the solid-phase method. 1.28 Ca 0.7 SiO4: 0.02Eu 2+ sample.

[0037] Control group implementation 2:

[0038] Samples were prepared using the coprecipitation method, according to the chemical formula Ba. 1.28 Ca 0.7SiO4: 0.02Eu 2+ Weigh the raw materials separately, and follow these steps:

[0039] Using NH4Cl as a flux, grind it into a fine powder, and weigh 0.12 g of it into an agate mortar for later use. Weigh 3.786 g of Ba(NO3)2, 1.842 g of Ca(NO3)2·4H2O, and 0.05 g of Eu(NO3)3·6H2O and dissolve them in 50 mL of deionized water to form solution A. Weigh 2.322 g of ethyl silicate and dissolve it in 30 mL of anhydrous ethanol to form solution B. Mix 20 mL of deionized water, 20 mL of anhydrous ethanol, and 30 mL of ammonia water to prepare a mother liquor. Slowly add solution B dropwise to the mother liquor. In the process, a SiO2 suspension was obtained, and 10 mg of ammonium bicarbonate was added as a precipitant to form solution C. Solution A was then added dropwise to C to obtain a mixed suspension D. The mixed suspension D was allowed to stand for a period of time, the supernatant was discarded, and the mixture was filtered and dried to obtain the precursor. The precursor was mixed evenly with the previously prepared NH4Cl in a mortar, then placed in a corundum crucible and placed in a furnace. Under a reducing atmosphere of H2 and N2 mixed in a volume ratio of 1:4, the mixture was heat-treated at 1200℃ for 8 hours. After cooling, a blocky crude product was obtained. The crude product was ground to obtain Ba co-precipitated by the method. 1.28 Ca 0.7 SiO4: 0.02Eu 2+ sample.

[0040] The XRD patterns of the phosphors obtained in Comparative Groups 1 and 2 and the phosphor obtained in Example 2 are shown below. Figure 4 As shown (obtained by X-ray diffraction (Smartlab9, Rigaku, Japan) test).

[0041] Example 4: Phosphor Performance Testing

[0042] The particle size range of the phosphors in Examples 1 and 2 was tested using a laser particle size analyzer (Zetasizer Nano, Malvern Panaco, Netherlands). The CIE color coordinates, peak wavelength, external quantum efficiency, and full width at half maximum (FWHM) of the phosphors in Examples 1 and 2 were obtained using a fluorescence spectrometer (EX-1000, Hangzhou Yuanfang). The results are shown in Table 1.

[0043] Table 1 shows the performance parameters of the phosphors obtained in Examples 1-2 of the present invention.

[0044] Table 1

[0045]

[0046] The various properties shown in Table 1, including CIE color coordinates, peak wavelength, external quantum efficiency, and full width at half maximum (FWHM), were measured by exciting the phosphor with near-ultraviolet light at 390 nm using a fluorescence spectrometer.

[0047] The phosphor obtained by the method described in Example 2 was tested using a fluorescence spectrometer (EX-1000, Hangzhou Yuanfang) and compared with the phosphors obtained by the methods described in Examples 1 and 2 of the control group under 390 nm excitation, along with their corresponding excitation spectra. The results are as follows: Figure 3 As shown, the results indicate that the phosphor prepared in Example 2 can emit blue light at 450 nm after being excited by ultraviolet light. This is the first time that a phosphor capable of emitting blue light has been discovered, and its spectral combination has important practical value in the field of plant lighting.

Claims

1. A near-ultraviolet light-excited silicate blue phosphor, characterized in that, The chemical formula is Ba 1.3-x Ca 0.7 SiO4:xEu 2 + , where x is 0.005-0.

05.

2. The silicate blue phosphor according to claim 1, characterized in that, x is 0.02 or 0.

04.

3. The silicate blue phosphor according to claim 1 or 2, characterized in that, The average particle size is 7~8μm, and it emits 450nm blue light after being excited by ultraviolet light.

4. The method for preparing the silicate blue phosphor according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Select NH4Cl or BaCl2 as fluxing material and ball mill it into fine powder; (2) Weigh out the required Ba(NO3)2, Ca(NO3)2·4H2O and Eu(NO3)3·6H2O according to the stoichiometric ratio and dissolve them in deionized water to form solution A; (3) Weigh out ethyl silicate according to the stoichiometric ratio and dissolve it in anhydrous ethanol to form solution B; (4) Mix a certain proportion of deionized water, ethanol and ammonia to prepare a mother liquor; (5) Slowly add solution B from step (3) to the mother liquor from step (4) to obtain SiO2 suspension, and then add a certain amount of ammonium bicarbonate as a precipitant to form solution C; (6) Slowly add solution A from step (2) to solution C from step (5) to obtain a mixed suspension D; (7) The suspension D obtained in step (6) is placed into a high pressure vessel, placed in an oven and heated at 200~250℃ for 4-16 hours. After taking it out, it is then filtered and dried to obtain the precursor. (8) The precursor obtained in step (7) and the flux described in step (1) are mixed in a ratio of 0.5-8% by mass of the precursor and the flux. The mixture is then heat-treated at 1100-1300℃ for 2-10 hours in a reducing atmosphere. After cooling to room temperature, a blocky crude product is obtained. The final product is obtained by ball milling.

5. The preparation method according to claim 4, characterized in that, The volume ratio of deionized water, ethanol and ammonia in step (4) is 1:1:1.5 to 1:1:

3.

6. The preparation method according to claim 4, characterized in that, In step (5), the amount of ammonium bicarbonate added is 1.2-1.5 times the sum of the molar amounts of Ca and Ba.

7. The preparation method according to claim 4, characterized in that, Step (7) Place it in an oven and heat at 230℃ for 16 hours.

8. The preparation method according to claim 4, characterized in that, The reducing atmosphere in step (8) is a mixture of H2 and N2 in a volume ratio of 1:

4.

9. An LED light, characterized in that, Includes the silicate blue phosphor according to any one of claims 1-3.

10. The application of the LED lamp according to claim 9 in plant growth lighting.

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