A red and blue dual-color LED fluorescent powder for plant growth and preparation method thereof

Abstract

The present invention discloses a red and blue dual-color LED phosphor for plant growth and a preparation method thereof. The chemical composition of the phosphor is: Na2Zr 1‑x‑y (WO4)3:xNi 2+ ,yFe 2+ , where x is the doping concentration of Ni 2+ , x = 0.01 to 0.1, and y is the doping concentration of Fe 2+ , y = 0.01 to 0.1. When excited by ultraviolet light of 320 to 360 nm, the phosphor can emit high-intensity blue light of 400 to 500 nm and red light of 660 to 700 nm, corresponding to the absorption spectra of various pigments for the growth of plant roots, stems and leaves and photosynthesis, and can effectively promote the growth and development of plants. The raw materials of the phosphor are all non-rare earth materials, with low cost; the phosphor has small particle size, uniform particles and high luminous intensity; both the raw materials and the products are non-toxic and environmentally friendly, and it is a potential new luminescent material in the field of plant lighting LEDs.

Description

Technical Field

[0001] The invention belongs to the technical field of optoelectronic functional materials, and in particular relates to a red and blue dual-color LED fluorescent powder for plant growth and a preparation method thereof. Background Art

[0002] In the smart agriculture industry, plant lighting is an important branch field that uses artificial light sources to adjust lighting conditions to achieve the growth conditions required by plants. With the continuous progress of modern agriculture and the requirements for high-quality agricultural development, the demand for plant lighting in agricultural production has become more and more.

[0003] During plant growth and development, light can provide radiation energy for plant photosynthesis, and can also serve as a signal to effectively regulate the physiological processes of plants throughout their life cycle. In photosynthesis, photosynthetic pigments are important photoreceptors of plants, mainly including chlorophyll a, chlorophyll b and carotenoids. Chlorophyll a and chlorophyll b mainly absorb light in the wavelength range of 400~470nm blue light region and 600~700nm red light region. Carotenoids mainly absorb blue light in the wavelength range of 400~500nm.

[0004] In addition to photosynthesis, blue light plays an important role in plant growth, promoting the healthy growth and development of plants by affecting leaf development, root growth, chlorophyll synthesis, and plant morphology:

[0005] 1. Vegetative growth and leaf development: Blue light supports the vegetative growth of plants, affecting leaf development, root growth and overall plant size.

[0006] 2. Chlorophyll synthesis: Blue light promotes the synthesis of chlorophyll, which has a positive effect on the antioxidant capacity of plants.

[0007] 3. Plant morphology: Blue light inhibits stem elongation and helps the plant form a more compact structure.

[0008] Red light mainly has a positive effect on the flowering and fruiting of plants and prolongs the flowering period. It can promote the flowering and fruiting of plants, while prolonging the flowering period, allowing plants to photosynthesize and absorb nutrients for a longer time.

[0009] Therefore, blue light and red light play a huge role in plant growth. Through artificial plant lighting technology, plant growth lamps that emit red and blue light can be prepared, which can increase the growth rate of plants and improve the quality and quality of plants.

[0010] In terms of plant lighting sources, light-emitting diodes (LEDs), as the fourth generation of semiconductor light sources, have become a rising star in the plant lighting market and a current research hotspot with their advantages of high efficiency, energy saving, environmental protection, and long life. They are potential plant growth lamps that replace high-pressure sodium lamps with poor lighting sustainability and contain toxic metal mercury. The principle of LED light emission is to coat a semiconductor chip with phosphors, and use the light emitted by the chip to excite the phosphors to emit light, thereby obtaining light of a specific wavelength.

[0011] At present, there are many studies on red phosphors in the field of LED plant growth lamps, but few studies on red and blue dual-color luminescence. In the few studies, the luminescent ions used rare earth materials, which have high raw material costs; the luminescent center still tends to be red light, and the intensity of blue light is relatively low; the synthesis method is a solid-phase method, the sintering temperature is high, the phosphor is easy to agglomerate, the particles are large and uneven, and the luminous intensity is seriously affected.

[0012] For example, Chinese patent CN111575002A discloses a full-spectrum LED phosphor for plant supplementary lighting and a preparation method thereof. According to the chemical formula of the phosphor: Tb x M 3-x Ga5O 12 :yMn 4+ (M=Y, Gd, La, Lu, 0≤x≤3 ,0.1≤y≤5at%), the phosphor composition contains yttrium, gadolinium, lanthanum, lutetium and other rare earth ions, and the raw material cost is high; Chinese patent CN113072940A discloses a dual-emission phosphor for LED plant lighting and its preparation method, the chemical formula of the phosphor is K2Ca 1-x PO4F:xEu 2+ ,yA, using rare earth ion Eu 2+ As the luminescent ion, the solid phase method is used, the calcination temperature is high, 1100°C, and the red light intensity in the emission spectrum is relatively high; Chinese patent CN117844483A discloses a single-matrix dual-emission phosphor and its preparation method, the chemical formula is Ca 18-x-y Eu x Mn y Na3Y(PO4) 14 , still using the rare earth ion Eu 2+ As a luminescent ion, it adopts the solid phase method, the calcination temperature is as high as 1300℃, and the red light intensity in the emission spectrum is relatively high.

[0013] Therefore, the development of a low-cost, simple preparation condition, red and blue light bands that meet the needs of plant growth, especially a two-color phosphor that can emit high-intensity blue light, is of great significance to the field of LED plant lighting. Summary of the invention

[0014] The object of the present invention is to provide a red and blue dual-color LED phosphor for plant growth, which can be excited by 320-360nm ultraviolet light, emit 400-500nm high-intensity blue light and 660-700nm red light, corresponding to the absorption spectrum of various pigments in plant photosynthesis, and can effectively promote the growth and development of plants; the present invention also provides a preparation method thereof.

[0015] The technical solution adopted by the present invention to solve the technical problem is:

[0016] The red and blue dual-color LED fluorescent powder for plant growth of the present invention has the chemical composition of: Na2Zr 1-x-y (WO4)3: xNi 2+ , yFe 2+ , where x is the doped Ni 2+ concentration, x = 0.01 ~ 0.1, preferably x = 0.03 ~ 0.08; y is the doped Fe 2+ Concentration, y=0.01~0.1, preferably y=0.03~0.08.

[0017] The method for preparing the red and blue dual-color LED phosphor for plant growth of the present invention is a liquid phase method + homogenization treatment, wherein a phosphor precursor is synthesized under liquid phase conditions, the precursor is homogenized, and an organic dispersant and a flux are added during sintering for homogenization, and the method comprises the following steps:

[0018] (1) Weigh Zr(NO3)4, Na2WO4 and a doping compound according to the stoichiometric ratio; prepare Zr(NO3)4 and the doping compound into a solution with deionized water to form a mother salt solution A; add a dispersant to the aqueous solution of Na2WO4 to form a solution B;

[0019] (2) Using the back-drip method, the mother salt solution A is added dropwise to the solution B to generate a precipitate for aging, and then filtered, washed, and dried to obtain a phosphor precursor;

[0020] (3) homogenizing the prepared phosphor precursor;

[0021] (4) In a reducing atmosphere, the phosphor precursor is added to an organic dispersant for pre-sintering, and after the pre-sintering is completed, a homogenization treatment is performed;

[0022] (5) In a reducing atmosphere, a flux is added to further sinter the pre-sintered phosphor precursor, and the pre-sintered phosphor precursor is cooled to obtain the red and blue dual-color LED phosphor.

[0023] in:

[0024] In step (1), the molar ratio of Zr(NO3)4 to Na2WO4 is 0.8-0.98:3, preferably 0.85-0.95:3.

[0025] In step (1), there are two doping compounds, one of Ni(NO3)2, NiSO4, NiCl2, Ni(CH3COO)2 and one of Fe(NO3)2, FeSO4, FeCl2, Fe(CH3COO)2.

[0026] In step (1), the molar ratio of the two doping compounds to Zr(NO3)4 is 0.01-0.1:0.01-0.1:0.8-0.98, preferably 0.03-0.08:0.03-0.08:0.85-0.95.

[0027] In step (1), the dispersant is one or more of sodium pyrosulfate, glycerol, ethanol, and n-butanol, and the molar ratio of Na2WO4 to the dispersant is 3:0.01-0.1, preferably 3:0.02-0.08.

[0028] In step (2), the dripping rate is 4-6 ml / min, preferably 3-5 ml / min; the aging time is 10-30 min, and the drying temperature is 80-100°C.

[0029] In steps (3) and (4), the homogenization treatment method is ultrasonic dispersion or centrifugal dispersion.

[0030] In step (4), the organic dispersant is one or more of ethanol, acetic acid, glycerol, n-heptane, petroleum ether, ethylenediaminetetraacetic acid or sodium dodecylbenzenesulfonate, and the molar ratio of the organic dispersant to the phosphor precursor is 0.01-0.1:1, preferably 0.03-0.08:1.

[0031] In steps (4) and (5), the reducing atmosphere is generated by the added carbon powder.

[0032] In step (4), the pre-sintering temperature is 200-300° C., and the pre-sintering time is 2-3 hours.

[0033] In step (5), the sintering temperature is 800-900° C. and the sintering time is 2-5 hours.

[0034] In step (5), the flux is one or more of boric acid, sodium borate, phosphoric acid, sodium chloride, ammonium chloride, and potassium chloride, and the molar ratio of the flux to the phosphor precursor is 0.01-0.1:1, preferably 0.03-0.07:1.

[0035] The beneficial effects of the present invention are as follows:

[0036] The present invention adopts a novel zirconate tungstate system to prepare a red and blue dual-color phosphor, and the doped luminescent ions used are Ni 2+ and Fe 2+ , are all non-rare earth ions, and the synthetic raw materials are cheap; the crystal structure of zirconate tungstate belongs to the tetragonal system, and there is a large range of cation substitution in its crystal structure. What kind of ions are replaced by the cations entering the matrix depends mainly on the ionic radius between the mutually replaced ions. 2+ , Fe 2+ With Zr 4+ have similar effective ionic radius (when CN=4, Ni 2+ The radius is 0.65nm, Fe 2+ The radius of Zr is 0.63nm. 4+ The radius is 0.59nm), and W 6+ The ionic radius of 6+ The radius is 0.42nm), so when Ni enters the lattice of zirconate tungstate, 2+ , Fe 2+ It is replaced by Zr 4+ The phosphor of the present invention is subjected to plasma emission spectroscopy (ICP) analysis. The ICP results show that the content of each metal ion in the phosphor satisfies the stoichiometric relationship of the chemical formula of the phosphor Na2Zr(WO4)3. The doping ion Ni 2+ and Fe 2+ Replaced by Zr 4+ location.

[0037] Compared with the traditional phosphors for plant growth, the present invention adopts a zirconate tungstate system with excellent high temperature stability, good chemical stability and high mechanical strength, and utilizes the doping of non-rare earth luminescent ions Ni 2+ and Fe 2+ Substituting Zr in the matrix 4+ , low raw material cost; the obtained phosphor can produce 400-500nm high-intensity blue light and 660-700nm red light, corresponding to the absorption spectrum of various pigments in plant root, stem and leaf growth and photosynthesis, and can effectively promote plant growth and development. The raw materials of the present invention are all non-rare earth materials, and both the raw materials and products are non-toxic and environmentally friendly, which is a potential new luminescent material in the field of plant lighting LED.

[0038] The preparation method of the present invention adopts a liquid phase method + homogenization treatment method. The liquid phase method is adopted to make the crystal ions evenly distributed, control the nucleus formation and crystal growth process, so as to obtain an ideal precursor with small and uniform particles; the homogenization method for preparing the precursor and the phosphor is innovative: adding a dispersant during the precursor synthesis process, ultrasonically or centrifugally homogenizing the precursor before and after pre-sintering, and adding an organic dispersant during the precursor calcination process. These methods can make the particles of the precursor and the phosphor evenly distributed, so that the powder calcination is more uniform and the luminous efficiency of the phosphor is better; adding a flux in the precursor calcination stage not only effectively reduces the sintering temperature, saves sintering time, and improves production efficiency and quality, but also improves the fusibility and adhesion of the precursor, so that the precursor particles can be better dispersed and sintered. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is the X-ray diffraction pattern of the red and blue dual-color phosphor prepared in Example 1;

[0040] Figure 2 The excitation spectrum of the red and blue dual-color phosphor prepared in Example 1;

[0041] Figure 3 is the emission spectrum of the red and blue dual-color phosphors prepared in Examples 1 to 3 and Comparative Example 1;

[0042] Figure 4 is a SEM image of the red and blue dual-color phosphors prepared in Examples 1 to 3 and Comparative Example 1, Figure 4 (a) is a SEM image of the phosphor prepared in Example 1. Figure 4 (b) is a SEM image of the phosphor prepared in Example 2. Figure 4 (c) is a SEM image of the phosphor prepared in Example 3. Figure 4 (d) is the SEM image of the phosphor prepared in Comparative Example 1. DETAILED DESCRIPTION

[0043] The present invention is further described below in conjunction with specific implementation modes, but the embodiments do not limit the present invention in any form.

[0044] Example 1

[0045] Na2Zr 0.9 (WO4)3: 0.05Ni 2+ , 0.05Fe 2+ The specific steps for preparing phosphor are as follows:

[0046] (1) According to the chemical formula Na2Zr 0.9 (WO4)3: 0.05Ni 2+ , 0.05Fe2+ The stoichiometric ratio is 0.09 mol Zr(NO3)4 and 0.3 mol Na2WO4 as the main reactants, and the doped compounds are 0.005 mol Ni(NO3)2 and 0.005 mol Fe(NO3)2.

[0047] Zr(NO3)4, Ni(NO3)2, and Fe(NO3)2 were prepared into a clear solution with deionized water to form a mother salt solution A, in which the total concentration of metal cations was 0.2 mol / L; Na2WO4 was prepared into a 1.2 mol / L aqueous solution, and sodium pyrosulfate was added thereto as a dispersant to form a solution B, in which the molar ratio of Na2WO4 to sodium pyrosulfate was 3:0.05;

[0048] (2) Using the back-drip method, the mother salt solution A is added dropwise to the solution B at a dropping speed of 5 ml / min. The resulting precipitate is aged for 20 min, then filtered, washed with water and anhydrous ethanol solution to remove various compounds attached to the precipitate, and then dried at 80°C to obtain a phosphor precursor;

[0049] (3) Place the prepared phosphor precursor into an ultrasonic disperser and homogenize for 10 minutes;

[0050] (4) The homogenized phosphor precursor was added to 0.005 mol of glycerol and pre-sintered at 250°C for 2 hours in a carbon powder reducing atmosphere. After cooling to room temperature, the phosphor precursor was placed in an ultrasonic disperser again and homogenized for 10 minutes.

[0051] (5) Then, in a carbon powder reducing atmosphere, 0.005 mol of boric acid as a flux was added, and the mixture was sintered at 900° C. for 3 hours. The mixture was cooled to obtain a red and blue dual-color LED phosphor.

[0052] Through ICP analysis of the phosphor, the molar ratio of Na, Zr, W, Ni, and Fe is 2.03:0.90:2.98:0.05:0.05, and the content of each metal element satisfies the chemical formula of the phosphor: Na2Zr 0.9 (WO4)3: 0.05Ni 2+ , 0.05Fe 2+ The measurement relationship of

[0053] The phosphor was analyzed by X-ray diffraction, and its XRD diffraction pattern is as follows: Figure 1 As shown, the diffraction peaks of the phosphor have a good match with the Na2Zr(WO4)3 standard card, which proves that a small amount of Ni 2+ and Fe 2+ After being doped into the matrix, the structure of the matrix did not change. 2+ and Fe2+ Successfully entered the lattice of Na2Zr(WO4)3 crystal;

[0054] Figure 2 It is the excitation spectrum of the phosphor at room temperature. The phosphor has strong absorption in the range of 320~360nm and can match the LED UV chip well.

[0055] The emission spectrum of the phosphor at room temperature is as follows Figure 3 As shown, under excitation in the 354nm band, the emission spectrum shows strong dual emission characteristics of blue light and red light, where the wavelength range of blue light is 400~500nm, the wavelength range of red light is 660~700nm, and the main emission peaks are located at 428nm and 693nm, respectively.

[0056] The SEM image of the phosphor is shown in Figure 4 As shown in the figure, it can be seen that the prepared powder adopts the liquid phase method + homogenization treatment method, and the synthesized powder presents a good near-spherical morphology, a particle size of 2~6μm, and a uniform distribution of powder particles.

[0057] Example 2

[0058] Na2Zr 0.92 (WO4)3: 0.04Ni 2+ , 0.04Fe 2+ The specific steps for preparing phosphor are as follows:

[0059] (1) According to the chemical formula Na2Zr 0.92 (WO4)3: 0.04Ni 2+ , 0.04Fe 2+ The stoichiometric ratio is as follows: the main reactants are 0.092 mol Zr(NO3)4 and 0.3 mol Na2WO4, and the doped compounds are 0.004 mol NiSO4 and 0.004 mol FeSO4.

[0060] Zr(NO3)4, NiSO4 and FeSO4 were prepared into a clear solution with deionized water to form a mother salt solution A, in which the total concentration of metal cations was 0.2 mol / L; Na2WO4 was prepared into a 1.2 mol / L aqueous solution, and glycerol was added thereto as a dispersant to form a solution B, in which the molar ratio of Na2WO4 to glycerol was 3:0.05;

[0061] (2) Using the back-drip method, the mother salt solution A was added dropwise to the solution B at a dropping speed of 5 ml / min. The resulting precipitate was aged for 30 min, then filtered, washed with water and anhydrous ethanol solution to remove various compounds attached to the precipitate, and then dried at 100°C to obtain a phosphor precursor;

[0062] (3) Place the prepared phosphor precursor into an ultrasonic disperser and homogenize for 10 minutes;

[0063] (4) The homogenized phosphor precursor was added to 0.005 mol petroleum ether and pre-sintered at 300 °C for 2 hours in a carbon powder reducing atmosphere. After cooling to room temperature, the phosphor precursor was placed in an ultrasonic disperser again and homogenized for 10 minutes.

[0064] (5) Then, in a carbon powder reducing atmosphere, 0.005 mol of flux sodium borate was added, sintered at 900° C. for 3 hours, and cooled to obtain a red and blue dual-color LED phosphor.

[0065] Through ICP analysis of the phosphor, the molar ratio of Na, Zr, W, Ni, and Fe is 2.01:0.92:3.03:0.04:0.04, and the content of each metal element satisfies the chemical formula of the phosphor: Na2Zr 0.92 (WO4)3: 0.04Ni 2+ , 0.04Fe 2+ The measurement relationship of

[0066] The phosphor was subjected to X-ray diffraction analysis, and its XRD diffraction pattern was exactly the same as that of Example 1. Figure 1 As shown, it is proved that a small amount of Ni 2+ and Fe 2+ When added into Na2Zr(WO4)3 matrix, the structure of the matrix did not change. 2+ and Fe 2+ Successfully entered the lattice of Na2Zr(WO4)3 crystal;

[0067] The excitation spectrum of the phosphor at room temperature is exactly the same as that of Example 1. Figure 2 As shown, the phosphor has strong absorption in the range of 320~360nm and can match the LED UV chip well.

[0068] The emission spectrum of the phosphor at room temperature is as follows Figure 3 As shown, under excitation in the 354nm band, the emission spectrum shows strong dual emission characteristics of blue light and red light, where the wavelength range of blue light is 400~500nm, the wavelength range of red light is 660~700nm, and the main emission peaks are located at 429nm and 692nm, respectively.

[0069] The SEM image of the phosphor is shown in Figure 4 As shown in the figure, it can be seen that the prepared powder adopts the liquid phase method + homogenization treatment method, and the synthesized powder presents a good near-spherical morphology, a particle size of 2~6μm, and a uniform distribution of powder particles.

[0070] Example 3

[0071] Na2Zr 0.88 (WO4)3: 0.06Ni 2+ , 0.06Fe 2+ The specific steps for preparing phosphor are as follows:

[0072] (1) According to the chemical formula Na2Zr 0.88 (WO4)3: 0.06Ni 2+ , 0.06Fe 2+ The stoichiometric ratio is as follows: the main reactants are 0.088 mol Zr(NO3)4 and 0.3 mol Na2WO4, and the doped compounds are 0.006 mol NiCl2 and 0.006 mol FeCl2.

[0073] Zr(NO3)4, NiCl2, and FeCl2 were prepared into a clear solution with deionized water to form a mother salt solution A, in which the total concentration of metal cations was 0.2 mol / L; Na2WO4 was prepared into a 1.2 mol / L aqueous solution, and ethanol was added thereto as a dispersant to form a solution B, in which the molar ratio of Na2WO4 to ethanol was 3:0.05;

[0074] (2) Using the back-drip method, the mother salt solution A is added dropwise to the solution B at a dropping speed of 4 ml / min. The resulting precipitate is aged for 30 min, then filtered, washed with water and anhydrous ethanol solution to remove various compounds attached to the precipitate, and then dried at 100°C to obtain a phosphor precursor;

[0075] (3) Place the prepared phosphor precursor into a centrifugal homogenizer and homogenize for 5 minutes;

[0076] (4) The homogenized phosphor precursor was added to 0.005 mol of n-heptane and pre-sintered at 300 °C for 3 hours in a carbon powder reducing atmosphere. After cooling to room temperature, the phosphor precursor was placed in a centrifugal homogenizer again and homogenized for 5 minutes.

[0077] (5) Then, in a carbon powder reducing atmosphere, 0.005 mol of flux ammonium chloride was added, sintering was performed at 850° C. for 4 hours, and cooling was performed to obtain a red and blue dual-color LED phosphor.

[0078] Through ICP analysis of the phosphor, the molar ratio of Na, Zr, W, Ni, and Fe is 2.03:0.88:2.99:0.06:0.06, and the content of each metal element satisfies the chemical formula of the phosphor: Na2Zr 0.88 (WO4)3: 0.06Ni 2+, 0.06Fe 2+ The measurement relationship of

[0079] The phosphor was subjected to X-ray diffraction analysis, and its XRD diffraction pattern was exactly the same as that of Example 1. Figure 1 As shown, it is proved that a small amount of Ni 2+ and Fe 2+ When added into Na2Zr(WO4)3 matrix, the structure of the matrix did not change. 2+ and Fe 2+ Successfully entered the lattice of Na2Zr(WO4)3 crystal;

[0080] The excitation spectrum of the phosphor at room temperature is exactly the same as that of Example 1. Figure 2 As shown, the phosphor has strong absorption in the range of 320~360nm and can match the LED UV chip well.

[0081] The emission spectrum of the phosphor at room temperature is as follows Figure 3 As shown, under excitation in the 354nm band, the emission spectrum shows strong dual emission characteristics of blue light and red light, where the wavelength range of blue light is 400~500nm, the wavelength range of red light is 660~700nm, and the main emission peaks are located at 430nm and 693nm, respectively.

[0082] The SEM image of the phosphor is shown in Figure 4 As shown in the figure, it can be seen that the prepared powder adopts the liquid phase method + homogenization treatment method, and the synthesized powder presents a good near-spherical morphology, a particle size of 2~6μm, and a uniform distribution of powder particles.

[0083] Comparative Example 1

[0084] Na2Zr 0.9 (WO4)3: 0.05Ni 2+ , 0.05Fe 2+ The specific steps for preparing phosphor are as follows:

[0085] (1) According to the chemical formula Na2Zr 0.9 (WO4)3: 0.05Ni 2+ , 0.05Fe 2+ The stoichiometric ratio is 0.09 mol Zr(NO3)4 and 0.3 mol Na2WO4 as the main reactants, and the doped compounds are 0.005 mol Ni(NO3)2 and 0.005 mol Fe(NO3)2.

[0086] Zr(NO3)4, Ni(NO3)2, and Fe(NO3)2 are prepared into a clear solution with deionized water to form a mother salt solution A, in which the total concentration of metal cations is 0.2 mol / L; Na2WO4 is prepared into a 1.2 mol / L aqueous solution to form a solution B;

[0087] (2) Using the back-drip method, the mother salt solution A is added dropwise to the solution B at a dropping speed of 5 ml / min. The resulting precipitate is aged for 20 min, then filtered, washed with water and anhydrous ethanol solution to remove various compounds attached to the precipitate, and then dried at 80°C to obtain a phosphor precursor;

[0088] (3) Pre-sintering the prepared phosphor precursor at 250°C for 2 hours in a carbon powder reducing atmosphere and cooling to room temperature;

[0089] (4) Then, the pre-sintered phosphor precursor is sintered at 900° C. for 3 hours in a carbon powder reducing atmosphere and cooled to obtain a red and blue dual-color LED phosphor.

[0090] Through ICP analysis of the phosphor, the molar ratio of Na, Zr, W, Ni, and Fe is 1.99:0.90:2.97:0.05:0.05, and the content of each metal element satisfies the chemical formula of the phosphor: Na2Zr 0.9 (WO4)3: 0.05Ni 2+ , 0.05Fe 2+ The measurement relationship of

[0091] The phosphor was subjected to X-ray diffraction analysis, and its XRD diffraction pattern was exactly the same as that of Example 1. Figure 1 As shown, it is proved that a small amount of Ni 2+ and Fe 2+ When added into Na2Zr(WO4)3 matrix, the structure of the matrix did not change. 2+ and Fe 2+ Successfully entered the lattice of Na2Zr(WO4)3 crystal;

[0092] The excitation spectrum of the phosphor at room temperature is exactly the same as that of Example 1. Figure 2 As shown, the phosphor has strong absorption in the range of 320~360nm and can match the LED UV chip well.

[0093] The emission spectrum of the phosphor at room temperature is as follows Figure 3As shown, under excitation in the 354nm band, the emission spectrum shows dual emission characteristics of blue light and red light, where the wavelength range of blue light is 400~500nm, the wavelength range of red light is 660~700nm, and the main emission peaks are located at 428nm and 693nm respectively, but the luminescence intensity is low.

[0094] The SEM image of the phosphor is shown in Figure 4 As shown in the figure, it can be seen that due to the lack of homogenization treatment, the addition of organic dispersants and fluxes, and the use of only the liquid phase method + sintering preparation method, the synthesized powder has an irregular morphology and serious particle agglomeration.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing red and blue dual-color LED phosphor for plant growth, characterized in that: The following steps are involved: (1) Weigh Zr(NO3)4, Na2WO4 and a doping compound according to the stoichiometric ratio; prepare Zr(NO3)4 and the doping compound into a solution with deionized water to form a mother salt solution A; add a dispersant to the aqueous solution of Na2WO4 to form a solution B; (2) Using the back-drip method, the mother salt solution A is added dropwise to the solution B to generate a precipitate for aging, and then filtered, washed, and dried to obtain a phosphor precursor; (3) homogenizing the prepared phosphor precursor; (4) In a reducing atmosphere, the phosphor precursor is pre-sintered by adding an organic dispersant, and then homogenized after the pre-sintering is completed; (5) In a reducing atmosphere, a flux is added to further sinter the pre-sintered phosphor precursor, and the pre-sintered phosphor precursor is cooled to obtain the red and blue dual-color LED phosphor. The chemical composition of red and blue dual-color LED phosphor is: Na2Zr 1-x-y (WO4)3: xNi 2+ , yFe 2+ , where x is the doped Ni 2+ concentration, x=0.01~0.1, y is the doped Fe 2+ concentration, y = 0.01~0.1; In step (1), the molar ratio of Zr(NO3)4 and Na2WO4 is 0.8~0.98:3; there are two doping compounds, one of Ni(NO3)2, NiSO4, NiCl2, Ni(CH3COO)2 and one of Fe(NO3)2, FeSO4, FeCl2, Fe(CH3COO)2, and the molar ratio of the two doping compounds to Zr(NO3)4 is 0.01~0.1:0.01~0.1:0.8~0.

98.

2. The method for preparing the red and blue dual-color LED phosphor for plant growth according to claim 1, characterized in that: In step (1), the dispersant is one or more of sodium pyrosulfate, glycerol, ethanol, and n-butanol, and the molar ratio of Na2WO4 to the dispersant is 3:0.01~0.

1.

3. The method for preparing the red and blue dual-color LED phosphor for plant growth according to claim 1, characterized in that: In step (2), the dripping rate is 4-6 ml / min, the aging time is 10-30 min, and the drying temperature is 80-100°C.

4. The method for preparing the red and blue dual-color LED phosphor for plant growth according to claim 1, characterized in that: In steps (3) and (4), the homogenization treatment method is ultrasonic dispersion or centrifugal dispersion.

5. The method for preparing the red and blue dual-color LED phosphor for plant growth according to claim 1, characterized in that: In step (4), the organic dispersant is one or more of ethanol, acetic acid, glycerol, n-heptane, petroleum ether, ethylenediaminetetraacetic acid or sodium dodecylbenzenesulfonate, and the molar ratio of the organic dispersant to the phosphor precursor is 0.01-0.1:

1.

6. The method for preparing the red and blue dual-color LED phosphor for plant growth according to claim 1, characterized in that: In steps (4) and (5), the reducing atmosphere is generated by the added carbon powder.

7. The method for preparing the red and blue dual-color LED phosphor for plant growth according to claim 1, characterized in that: In step (4), the pre-sintering temperature is 200-300° C., and the pre-sintering time is 2-3 hours.

8. The method for preparing the red and blue dual-color LED phosphor for plant growth according to claim 1, characterized in that: In step (5), the sintering temperature is 800-900° C., and the sintering time is 2-5 hours; the flux is one or more of boric acid, sodium borate, phosphoric acid, sodium chloride, ammonium chloride, and potassium chloride, and the molar ratio of the flux to the phosphor precursor is 0.01-0.1:1.

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