Preparation method of green fluorescent powder of white LED lamp for plant supplementary lighting

Abstract

The invention belongs to the technical field of inorganic synthesis of luminescent materials, and discloses a preparation method of white LED (light-emitting diode) lamp green fluorescent powder for plant supplementary lighting, which comprises the following steps: accurately weighing raw materials MgO, Al2O3 and MnCO3 according to the chemical formula ratio of Mg1-xAl2O4: xMn, adding a fluxing agent H3BO4, putting into an agate mortar, grinding, and uniformly mixing; pouring the mixed powder into a corundum crucible, sintering in microwave heating equipment, naturally cooling to room temperature, and grinding by an agate mortar to finally obtain the Mg1-xAl2O4: xMn green fluorescent powder, the Mg1-xAl2O4: xMn fluorescent powder is synthesized by utilizing a microwave heating technology, and microwave sintering depends on an efficient absorption and conversion mechanism of the dielectric property of the material to microwave energy, so that fossil energy consumption is avoided, the preparation period can be shortened, the development concepts of environmental protection, energy conservation and carbon reduction are met, and the Mg1-xAl2O4: xMn fluorescent powder can be used for a green powder part in a white light LED plant illuminating lamp.

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic synthesis of luminescent materials, and in particular relates to a method for preparing green fluorescent powder of a white LED lamp for plant supplementary lighting. Background Art

[0002] Light is indispensable in the growth process of plants. Appropriate supplementary light can promote plant development, increase yield and improve crop quality. However, traditional supplementary lighting methods (such as incandescent lamps, fluorescent lamps, etc.) face challenges in application and promotion due to their high energy consumption, high cost and short life. In recent years, LED light sources have rapidly emerged in the field of plant supplementary lighting due to their low energy consumption, long life and environmental protection characteristics. Among them, the performance of phosphors has a decisive influence on the lighting quality of plant supplementary lighting LED lamps.

[0003] LED light sources usually use a composite structure of InGaN-based chips and blue and red phosphors. In fact, the addition of green phosphors can coordinate with red and blue light to regulate the growth and development of plants. The reason is that the plants in the red and blue LED composite light appear purple-gray, making it difficult to diagnose symptoms of diseases and disorders. This problem can be effectively solved by supplementing green light. Because the green light effect is complementary to the red and blue light effects, and green light will increase the chlorophyll content and photosynthesis efficiency of plants. Studies have shown that the dd electron transition of the transition metal Mn is a spin-forbidden transition, and Mn 2+ It has strong green light emission characteristics in the MgAl2O4 matrix, so it can be used as one of the ideal luminescence centers of plant supplementary lighting phosphors.

[0004] However, the mainstream preparation method of LED phosphors, including MgAl2O4:Mn phosphors, is still traditional high-temperature sintering, which consumes a lot of natural resources and energy, and is accompanied by carbon dioxide emissions, making the greenhouse effect currently facing the global climate even more serious. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for preparing green fluorescent powder of white LED lamps for plant supplementary lighting, which conforms to the development concept of green environmental protection, energy saving and carbon reduction, and can be used for the green powder part of white light LED plant lighting.

[0006] The technical solution adopted by the present invention is: a green fluorescent powder of a white LED lamp for plant supplementary lighting, whose physical structure is: Mg 1-x Al2O4:xMn, 0≤x≤0.1; under the excitation of near-ultraviolet blue light, the emission peak band of the green phosphor is located at 526nm.

[0007] The method for preparing the green fluorescent powder of the white LED lamp for plant supplementary lighting of the present invention comprises the following steps: Step 1: According to Mg 1-x Al2O4:xMn chemical formula ratio Accurately weigh the raw materials MgO, A12O3, MnCO3, add flux H3BO4, put the raw materials and flux powder into an agate mortar and grind for 25-35 minutes to mix evenly; Step 2: Pour the powder ground and mixed in step 1 into a corundum crucible, place 3 silicon carbide rods around the crucible as auxiliary heating bodies, and then put it into a microwave heating device, adjust the input power to heat the raw material powder at a rate of 10-15°C / min; then heat it to 800°C-1400°C at a rate of 20-40°C / min, sinter it for 30 minutes, and then cool it naturally to room temperature; Step 3: Grind with an agate mortar to obtain Mg 1-x Al2O4:xMn green phosphor.

[0008] Furthermore, the Mg 1-x In the Al2O4:xMn green phosphor, the molar ratio x of MnCO3 and MgO raw materials is between 0-10%.

[0009] Furthermore, the amount of the raw materials added is calculated by molar ratio, (MgO+MnCO3):A12O3=1:1, MgO:MnCO3=(1-x):x.

[0010] Furthermore, the added amount of the H3BO4 flux is 5% of the total mass of the raw materials MgO, A12O3, and MnCO3.

[0011] Furthermore, the microwave heating frequency is 2450±50 MHz, and the microwave heating power is 0.05-2 KW / min.

[0012] The present invention adopts a solid phase synthesis method to mix the raw material powders evenly to obtain a composite powder. Then, the auxiliary heating device and the microwave absorption effect of A12O3 itself under high temperature conditions are used for synergistic microwave heating. During microwave heating, A12O3 and the microwave field have a coupling effect, and a large amount of microwave plasma is generated under high temperature conditions, forming microwave hot spots and generating heat, so that the atomic interface diffusion rate between MgO, A12O3, and MnCO3 increases, thereby achieving Mg 1-x Rapid preparation of Al2O4:xMn phosphors.

[0013] Among them, the main function of placing three silicon carbide rods around the crucible in step 2 of the present invention is: using silicon carbide rods to assist heating under low temperature conditions to quickly raise the temperature to above the critical value Tc, and then relying on the absorption and conversion of microwave energy by the dielectric properties of A12O3 itself to achieve phase reaction between the raw materials.

[0014] The present invention uses microwave high temperature solid phase synthesis method to prepare Mg1-x Al2O4:xMn green phosphor has good phase purity, high luminous intensity, and stable chemical properties, meeting the application requirements of white light LED phosphors for plant supplementary lighting.

[0015] The present invention innovates the heating method and uses microwave heating technology to synthesize Mg 1-x Al2O4:xMn phosphor, microwave sintering relies on the material's own dielectric properties to efficiently absorb and convert microwave energy, that is, directly convert the incident microwave electromagnetic field energy into thermal energy inside the material. This process does not rely on the combustion of fossil fuels or external resistive heating elements, which not only avoids the consumption of fossil energy, but also shortens the preparation cycle, which meets the development needs of energy conservation and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 X-ray diffraction spectra of the phosphors of Examples 1-4 of the present invention.

[0017] Figure 2 1 and 2 are the excitation and emission spectra of the phosphors of Examples 1 and 2 of the present invention. DETAILED DESCRIPTION

[0018] The scheme of the present invention is further described by the following examples. In the following examples, the microwave heating frequency is 2450±50MHz, the microwave heating power is 0.05-2KW / min, and the raw material addition amount is calculated by molar ratio, (MgO+MnCO3):A12O3=1:1, MgO:MnCO3=(1-x):x.

[0019] Embodiment 1:

[0020] The preparation method of the green fluorescent powder of the white LED lamp for plant supplementary lighting is as follows: According to Mg 0.98 Al2O4:0.02Mn chemical formula ratio, accurately weigh about 6g of raw materials, the masses of each raw material are: MgO1.5876g, A12O34.0788g, MnCO30.092g, add 5% of the total mass of MgO, A12O3, MnCO3 flux H3BO4, H3BO4 is 0.2879g, grind in an agate mortar for 30min, grind and mix evenly, pour into a corundum crucible, place 3 silicon carbide rods around the crucible as auxiliary heating bodies, and then put it into a microwave heating equipment, adjust the input power to make the raw material powder heat up to 600℃ at a rate of 10℃ / min; then heat up to 1400℃ at a rate of 20℃ / min and high-temperature roast for 30min, then naturally cool to room temperature, and grind in an agate mortar to obtain Mg 0.98 Al2O4:0.02Mn green phosphor.

[0021] Embodiment 2:

[0022] The preparation method of the green fluorescent powder of the white LED lamp for plant supplementary lighting is as follows: According to Mg 0.9 Al2O4:0.1Mn chemical formula ratio, accurately weigh 6g of raw materials, the masses of each raw material are: MgO1.458g, A12O34.082g, MnCO30.46g, add 5% of the total mass of MgO, A12O3, MnCO3 flux H3BO4, H3BO4 is 0.3g, grind in an agate mortar for 30min, grind and mix evenly, pour into a corundum crucible, place 3 silicon carbide rods around the crucible as auxiliary heating bodies, and then put it into a microwave heating equipment, adjust the input power to make the raw material powder heat up to 600℃ at a rate of 15℃ / min; then heat up to 1400℃ at a rate of 40℃ / min and high temperature roast for 30min, then naturally cool to room temperature, and grind in an agate mortar to obtain Mg 0.9 Al2O4:0.1Mn green phosphor.

[0023] Embodiment 3:

[0024] The preparation method of the green fluorescent powder of the white LED lamp for plant supplementary lighting is as follows: According to Mg 0.9 Al2O4:0.1Mn chemical formula ratio, accurately weigh 6g of raw materials, the masses of each raw material are: MgO1.458g, A12O34.082g, MnCO30.46g, add 5% of the total mass of MgO, A12O3, MnCO3 flux H3BO4, H3BO4 is 0.3g, grind in an agate mortar for 30min, grind and mix evenly, pour into a corundum crucible, place 3 silicon carbide rods around the crucible as auxiliary heating bodies, and then put it into a microwave heating equipment, adjust the input power to make the raw material powder heat up to 600℃ at a rate of 12℃ / min; then heat up to 800℃ at a rate of 25℃ / min and high temperature roast for 30min, then naturally cool to room temperature, and grind in an agate mortar to obtain Mg 0.9 Al2O4:0.1Mn green phosphor.

[0025] Embodiment 4:

[0026] The preparation method of the green fluorescent powder of the white LED lamp for plant supplementary lighting is as follows: According to Mg 0.9Al2O4:0.1Mn chemical formula ratio, accurately weigh 6g of raw materials, the masses of each raw material are: MgO1.458g, A12O34.082g, MnCO30.46g, add 5% of the total mass of MgO, A12O3, MnCO3 flux H3BO4, H3BO4 is 0.3g, grind in an agate mortar for 30min, grind and mix evenly, pour into a corundum crucible, place 3 silicon carbide rods around the crucible as auxiliary heating bodies, and then put it into a microwave heating equipment, adjust the input power to make the raw material powder heat up to 600℃ at a rate of 15℃ / min; then heat up to 1100℃ at a rate of 30℃ / min and high temperature roast for 30min, then naturally cool to room temperature, and grind in an agate mortar to obtain Mg 0.9 Al2O4:0.1Mn green phosphor.

[0027] Although the above embodiments describe specific implementation methods of the present invention, those skilled in the art should understand that these are only examples, and various changes or modifications can be made to the implementation methods without departing from the principles and essence of the present invention, and all belong to the protection scope of the present invention.

Claims

1. A method for preparing green fluorescent powder of white LED lamp for plant supplementary lighting, characterized in that: The following steps are involved: Step 1: According to Mg 1-x Al2O4:xMn chemical formula ratio Accurately weigh the raw materials MgO, A12O3, MnCO3, add flux H3BO4, put the raw materials and flux powder into an agate mortar and grind for 25-35 minutes to mix evenly; Step 2: Pour the powder ground and mixed in step 1 into a corundum crucible, place 3 silicon carbide rods around the crucible as auxiliary heating bodies, and then put it into a microwave heating device, adjust the input power to heat the raw material powder to 600°C at a rate of 10-15°C / min, and then heat it to 800°C-1400°C at a rate of 20-40°C / min, sinter for 30 minutes, and then naturally cool to room temperature; Step 3: Grind with an agate mortar to obtain Mg 1-x Al2O4:xMn green phosphor, 0≤x≤0.

1.

2. The method for preparing green fluorescent powder of white LED lamp for plant supplementary lighting according to claim 1, characterized in that: Mg 1-x In the Al2O4:xMn green phosphor, the molar ratio x of MnCO3 and MgO raw materials is between 0-10%.

3. The method for preparing green fluorescent powder of white LED lamp for plant supplementary lighting according to claim 1, characterized in that: The amount of raw materials added is calculated by molar ratio, (MgO+MnCO3):A12O3=1:1, MgO:MnCO3=(1-x):x.

4. The method for preparing green fluorescent powder of white LED lamp for plant supplementary lighting according to claim 1, characterized in that: The amount of H3BO4 flux added is 5% of the total mass of the raw materials MgO, A12O3, and MnCO3.

5. The method for preparing green fluorescent powder of white LED lamp for plant supplementary lighting according to claim 1, characterized in that: The microwave heating frequency is 2450±50MHz, and the microwave heating power is 0.05-2KW / min.

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