A Mn 4+ Activated deep red light emitting phosphor for plant growth and preparation method and application thereof

Abstract

The present invention discloses a Mn 4+ The invention relates to an activated deep red light emitting phosphor for plant growth and its preparation method and application, belonging to the technical field of solid luminescent materials. The chemical formula of the phosphor is La 2‑2x‑z A 2x Mg(Al 1 / 2‑x‑z W z ,Ta 1 / 2+x )O6:yMn 4+ , where A is one or more combinations of Ca, Sr, and Ba; the value range of x is 0 ≤ x ≤ 1 / 2; the value range of y is 0 < y ≤ 0.3; the value range of z is 0 ≤ z ≤ 1 / 2; and x + z ≤ 1 / 2. The synthesized phosphor of the present invention can effectively convert ultraviolet light and some visible light in sunlight into far-red light. It has high quantum efficiency, good water stability, and good overlap of its emission spectrum with the absorption band of plant phytochromes. When used in light-conversion thin films to supplement light for stem-leaf plants and fruit-bearing plants, it can effectively enhance photosynthesis efficiency, shorten the growth cycle, and improve plant yield and fruit quality. It has good application prospects in the field of plant cultivation.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid luminescent materials, and specifically relates to a Mn 4+ Activated deep red light emitting phosphor for plant growth, preparation method and application thereof. Background Art

[0002] Light is one of the key factors affecting plant growth and plays a vital regulatory role in plant growth, development and morphological formation. Light is the main source of energy for plant growth, but plants do not absorb light across the entire wavelength range but selectively. The wavelength of sunlight incident vertically on the ground is 280-3000nm, and only about 5% of the solar radiation spectrum has a significant effect on photosynthesis. The basic light requirements for plant growth and development are distributed in the blue light (400-500nm), red light (600-690nm) and far-red light (720-740nm) regions. These three regions are mainly responsible for phototropic processes, photosynthesis, photoperiodic response and photomorphogenesis. Studies have shown that the absorption spectrum of chlorophyll a / b in plants is mainly concentrated in the blue light band of 400-460nm, while the photosensitive pigment P r / P fr The absorption peak of light is located in the red / far-red band of 600-750nm, while light in other bands is rarely absorbed and has a low contribution to photosynthesis. In plant cultivation, if the sunlight energy that is not effectively utilized by plants (ultraviolet light and the vast majority of yellow-green light that is reflected and cannot be absorbed) can be converted into blue light and red / far-red light that can be effectively utilized by photosynthesis, the photosynthesis of plants can be enhanced, the growth cycle of plants can be shortened, and the yield and quality of plants can be improved.

[0003] There are three main methods for supplemental lighting for plants: 1. Traditional light sources such as incandescent, fluorescent, and high-pressure sodium lamps; 2. LED plant lights; and 3. Light-conversion films for plant growth. Traditional plant light sources have drawbacks such as high energy consumption, low light efficiency, short lifespan, non-adjustable spectra, and mismatch with plant absorption spectra. Newer LED supplemental lighting systems have some potential for application, but their poor spectral continuity, device module assembly, and energy consumption during plant lighting indirectly increase cultivation costs, requiring further development and improvement. Light-conversion films for plant growth have become another option for supplemental lighting. They convert ultraviolet and some visible light from sunlight into blue and red light, effectively improving plant light quality, increasing the overall utilization of light energy, and promoting plant growth.

[0004] At present, the main red phosphors used for plant growth are: Eu 2+ Activated alkaline earth metal sulfides (such as (Sr,Ca)S:Eu 2 + ), sulfide phosphors have poor chemical stability and are easy to deliquesce to produce harmful gases such as H2S, which is not friendly to the surrounding environment; while Eu 2+ Activated nitrides (such as Sr2Si5N8:Eu 2+ ,CaAlSiN3:Eu 2+ ) The synthesis conditions of red phosphor are harsh, requiring high-purity nitride raw materials, and are achieved under high temperature and high pressure (1600°C, above 10 atmospheres) and protective atmosphere. It is difficult to obtain a single phase, the preparation cost is high, and the water stability / humidity resistance is poor; Eu 3+ 、Sm 3+ and Pr 3+ The narrow-band red phosphor activated by trivalent rare earth ions represented by Cr has a characteristic ff transition as a forbidden transition. The phosphor is mainly excited by ultraviolet light and has weak absorption in the blue light region. The emission spectrum has a poor match with the plant absorption spectrum. 3+ The activated near-infrared phosphor has low absorption efficiency and Cr 3+ The valence state is unstable, and some Cr 3+ Easily reduced to Cr 4+ , the luminous efficiency needs to be further improved, the probability of non-radiative transition is high at high temperature, and the thermal stability is poor. In summary, several types of red phosphors have many problems, which limit their application in plant growth.

[0005] Therefore, there is an urgent need to develop a red phosphor material that can be effectively excited by near-ultraviolet light or visible light, has a good match between the emission spectrum and the plant absorption spectrum, and has high luminous efficiency and excellent physical and chemical stability. Summary of the Invention

[0006] The purpose of the present invention is to provide a Mn 4+ Activated deep red light emitting phosphor for plant growth, preparation method and application thereof. The luminescent material has high luminous efficiency and good water stability, can effectively absorb near-ultraviolet or blue-green light and convert it into deep red light, thereby promoting plant growth.

[0007] The Mn provided by the present invention 4+ The activated deep red light emitting phosphor for plant growth has a double perovskite structure, a monoclinic crystal system, and a space group of P21 / n. It has a broadband excitation in the range of 200-550nm and emits red and deep red light in the range of 600-750nm, which is similar to the plant photosensitive pigment P r and P fr The absorption spectra overlap well.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A Mn 4+ Activated deep red light emitting plant growth phosphor, its chemical formula is La 2-2x-z A 2x Mg(Al 1 / 2-x- z W z ,Ta 1 / 2+x )O6:yMn 4+ , wherein A is one or more combinations of Ca, Sr, and Ba, the value range of x is 0≤x≤1 / 2; the value range of y is 0<y≤0.3; preferably y=0.005-0.15; the value range of z is 0≤z≤1 / 2, preferably z=0.25; and x+z≤1 / 2.

[0010] The phosphor can be excited by near-ultraviolet and blue light at the same time, with an excitation spectrum covering 200-600nm and an emission main peak located between 600-800nm.

[0011] The Mn 4+ The method for preparing an activated deep red light emitting phosphor comprises the following steps:

[0012] 1) According to the chemical formula La 2-2x-z A 2x Mg(Al 1 / 2-x-z W z ,Ta 1 / 2+x )O6:yMn 4+ According to the stoichiometric ratio of each element in the mixture, the raw materials and flux are accurately weighed, and they are fully ground and mixed to obtain a mixture;

[0013] 2) The mixture obtained in step 1 is placed in an alumina crucible, sintered in two steps of pre-sintering and calcining, cooled to room temperature with the furnace, and the product is ground into powder to prepare a double perovskite structure deep red light emitting phosphor for plant growth.

[0014] Preferably, in step 1), the raw material is one or more of oxides, hydroxides, fluorides, chlorides, carbonates, nitrates, phosphates, ammonium salts, acetates or oxalates of lanthanum, calcium, strontium, barium, magnesium, aluminum, tungsten, tantalum and manganese.

[0015] Preferably, in step 1), the flux is at least one of NH4Cl, Li2CO3, and H3BO3, and the amount of the flux added is 1 to 10 wt%.

[0016] Preferably, in step 1), the grinding time is 10-60 min.

[0017] Preferably, in step 2), the sintering atmosphere is air, and the heating rate is 5°C / min.

[0018] Preferably, in step 2), the pre-sintering temperature is 850-900° C., and the holding time is 3-6 hours. The calcining temperature is 1450-1600° C., and the holding time is 6-8 hours.

[0019] Furthermore, the present invention also provides the use of the deep red light emitting phosphor in a light conversion film for promoting plant growth.

[0020] The light conversion film for plant growth is prepared by mixing deep red light emitting phosphor and polymer in a certain proportion.

[0021] Preferably, the polymer is at least one of epoxy resin (AB glue), polydimethylsiloxane (PDMS), polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polyvinyl acetate (PVAc), polyvinyl alcohol (PVA), ethylene-vinyl acetate (EVA), polycarbonate (PC), polystyrene (PS), polyethylene terephthalate (PET), and polymethacrylate (PMMA), and the mixing ratio of the phosphor to the polymer is 1:2-100.

[0022] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0023] 1. Mn provided by the present invention 4+ The activated double perovskite structure phosphor has an emission spectrum covering the range of 600-800nm ​​under near-ultraviolet or visible light excitation, with the strongest emission peak at 706nm, which is similar to the plant photosensitive pigment P r / P fr The absorption spectra of the two materials overlap well, effectively increasing the photosynthesis rate of plants. Furthermore, they exhibit excellent quantum efficiency and water stability, allowing them to maintain their original luminous intensity over long periods of time in the humid environments required for plant growth, demonstrating promising application prospects in plant lighting.

[0024] 2. The light conversion film provided by the present invention can use sunlight to supplement the light of stem, leaf, and fruit plants, which can effectively reduce energy consumption during plant cultivation, enhance plant photosynthesis efficiency, shorten the growth cycle, increase yield and fruit quality, and help improve economic benefits.

[0025] 3. Mn provided by the present invention 4+ The invention relates to a preparation method of an activated deep red light emitting phosphor, which has the advantages of simple process, no need for protective atmosphere, easy synthesis, environmentally friendly production process and conducive to mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1is a comparison chart of the X-ray diffraction patterns of the phosphors synthesized in Examples 1-8 and a standard data card;

[0027] Figure 2 1 is the excitation spectrum and emission spectrum of the phosphor synthesized in Example 2;

[0028] Figure 3 The emission spectrum of the phosphor obtained in Example 3 is the same as that of the photosensitive pigment P r and P fr and a comparison of the absorption spectra of chlorophyll a / b;

[0029] Figure 4 The water stability test results of the phosphor synthesized in Example 4 under 85°C / 85%H conditions are shown;

[0030] Figure 5 This is a graph of the quantum efficiency of the phosphor synthesized in Example 5;

[0031] Figure 6 is the solar reflection spectrum of the PP film in Example 12;

[0032] Figure 7 is the solar light reflection spectrum of the PDMS film in Example 13;

[0033] Figure 8 The experimental graph of the light conversion film promoting the growth of lettuce in Example 12, as well as the standard error graph and significance analysis of the dry and fresh weights;

[0034] Figure 9 This is an experimental diagram of the light conversion film in Example 12 promoting the growth of cherry tomatoes, as well as a standard error diagram and significance analysis of dry and fresh weights. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It is apparent that the embodiments described are only a portion of the embodiments of the present invention, rather than all of them. All other embodiments obtained by persons of ordinary skill in the art without creative effort are intended to fall within the scope of protection of the present invention.

[0036] Example 1

[0037] This embodiment provides a La2Mg(Al 0.5 Ta 0.5 )O6:0.005Mn 4+The phosphor powder is prepared by the following steps: 0.6516 g of La2O3, 0.0806 g of MgO, 0.0510 g of Al2O3, 0.2209 g of Ta2O5 and 0.0011 g of MnCO3 are weighed according to the stoichiometric ratio of each element, all the raw materials are thoroughly ground and mixed with 0.03 g of NH4Cl, and then placed in an alumina crucible, and then placed in a high-temperature furnace, heated to 850°C at a heating rate of 5°C / min in an air atmosphere, pre-fired for 6 hours, and then heated to 1550°C at the same heating rate and calcined for 8 hours, and then cooled to room temperature in the furnace, and then ground to obtain La2Mg(Al2O3). 0.5 Ta 0.5 )O6:0.005Mn 4+ Phosphor.

[0038] Example 2

[0039] This embodiment provides a La 1.75 Ba 0.25 Mg(Al 0.375 Ta 0.625 )O6:0.005Mn 4+ The phosphor powder preparation method comprises the following steps: weighing 0.5702g of La2O3, 0.0987g of BaCO3, 0.0806g of MgO, 0.0382g of Al2O3, 0.2762g of Ta2O5 and 0.0011g of MnCO3 according to the stoichiometric ratio of each element, grinding and mixing all the raw materials with 0.03g of NH4Cl, placing them in an alumina crucible, and then placing them in a high-temperature furnace, heating them to 850°C at a heating rate of 5°C / min in an air atmosphere, pre-calcining them for 6h, then heating them to 1550°C at the same heating rate and calcining them for 8h, cooling them to room temperature in the furnace, and grinding them to obtain La2O3. 1.75 Ba 0.25 Mg(Al 0.375 Ta 0.625 )O6:0.005Mn 4+ Phosphor.

[0040] Example 3

[0041] This embodiment provides a La 1.5 Ba 0.5 Mg(Al 0.25 Ta 0.75 )O6:0.005Mn 4+The phosphor powder is prepared by the following steps: 0.4887 g of La2O3, 0.1973 g of BaCO3, 0.0806 g of MgO, 0.0255 g of Al2O3, 0.3314 g of Ta2O5 and 0.0011 g of MnCO3 are weighed according to the stoichiometric ratio of each element, all the raw materials and 0.03 g of NH4Cl are fully ground and mixed, and then placed in an alumina crucible, and then placed in a high-temperature furnace, heated to 850°C at a heating rate of 5°C / min in an air atmosphere, pre-fired for 6 hours, and then heated to 1550°C at the same heating rate and calcined for 8 hours, and then cooled to room temperature in the furnace, and then ground to obtain La2O3. 1.5 Ba 0.5 Mg(Al 0.25 Ta 0.75 )O6:0.005Mn 4+ Phosphor.

[0042] Example 4

[0043] This embodiment provides a La 1.5 Ba 0.5 Mg(W 0.25 Ta 0.75 )O6:0.005Mn 4+ The phosphor powder is prepared by the following steps: 0.4887g of La2O3, 0.1973g of BaCO3, 0.0806g of MgO, 0.1249g of H2WO4, 0.3314g of Ta2O5 and 0.0011g of MnCO3 are weighed according to the stoichiometric ratio of each element, all the raw materials and 0.03g of NH4Cl are fully ground and mixed, and then placed in an alumina crucible, and then placed in a high-temperature furnace, heated to 850°C at a heating rate of 5°C / min in an air atmosphere, pre-fired for 6h, and then heated to 1550°C at the same heating rate and calcined for 8h, and then cooled to room temperature in the furnace, and then ground to obtain La2O3. 1.5 Ba 0.5 Mg(W 0.25 Ta 0.75 )O6:0.005Mn 4+ Phosphor.

[0044] Example 5

[0045] This embodiment provides a La 1.25 Ba 0.5 Mg(W 0.25 Ta 0.75 )O6:0.005Mn 4+The phosphor powder preparation method comprises the following steps: 0.4073g of La2O3, 0.1973g of BaCO3, 0.0806g of MgO, 0.1249g of H2WO4, 0.3314g of Ta2O5 and 0.0011g of MnCO3 are weighed according to the stoichiometric ratio of each element, all the raw materials and 0.03g of NH4Cl are fully ground and mixed, and then placed in an alumina crucible, and then placed in a high-temperature furnace, heated to 850°C at a heating rate of 5°C / min in an air atmosphere, pre-fired for 6h, and then heated to 1550°C at the same heating rate and calcined for 8h, and then cooled to room temperature in the furnace, and then ground to obtain La2O3. 1.25 Ba 0.5 Mg(W 0.25 Ta 0.75 )O6:0.005Mn 4+ Phosphor.

[0046] Example 6

[0047] This embodiment provides a La 1.25 Sr 0.5 Mg(W 0.25 Ta 0.75 )O6:0.005Mn 4+ The phosphor powder preparation method comprises the following steps: 0.4073g of La2O3, 0.1476g of SrCO3, 0.0806g of MgO, 0.1249g of H2WO4, 0.3314g of Ta2O5 and 0.0011g of MnCO3 are weighed according to the stoichiometric ratio of each element, all the raw materials and 0.03g of NH4Cl are fully ground and mixed, and then placed in an alumina crucible, and then placed in a high-temperature furnace, heated to 850°C at a heating rate of 5°C / min in an air atmosphere, pre-calcined for 6h, and then heated to 1550°C at the same heating rate and calcined for 8h, and then cooled to room temperature in the furnace, and then ground to obtain La2O3. 1.25 Sr 0.5 Mg(W 0.25 Ta 0.75 )O6:0.005Mn 4+ Phosphor.

[0048] Example 7

[0049] This embodiment provides a La 1.25 Ca 0.5 Mg(W 0.25 Ta 0.75 )O6:0.005Mn 4+The phosphor powder preparation method comprises the following steps: 0.4073g of La2O3, 0.1001g of CaCO3, 0.0806g of MgO, 0.1249g of H2WO4, 0.3314g of Ta2O5 and 0.0011g of MnCO3 are weighed according to the stoichiometric ratio of each element, all the raw materials and 0.03g of NH4Cl are fully ground and mixed, and then placed in an alumina crucible, and then placed in a high-temperature furnace, heated to 850°C at a heating rate of 5°C / min in an air atmosphere, pre-calcined for 6h, and then heated to 1550°C at the same heating rate and calcined for 8h, and then cooled to room temperature in the furnace, and then ground to obtain La2O3. 1.25 Ca 0.5 Mg(W 0.25 Ta 0.75 )O6:0.005Mn 4+ Phosphor.

[0050] Example 8

[0051] This embodiment provides a La 1.75 Mg(Al 0.25 W 0.25 Ta 0.5 )O6:0.005Mn 4+ The phosphor is prepared by the following steps: 0.5702 g of La2O3, 0.0806 g of MgO, 0.0255 g of Al2O3, 0.1249 g of H2WO4, 0.2209 g of Ta2O5 and 0.0011 g of MnCO3 are weighed according to the stoichiometric ratio of each element, all the raw materials and 0.03 g of NH4Cl are fully ground and mixed, and then placed in an alumina crucible, and then placed in a high-temperature furnace, heated to 850°C at a heating rate of 5°C / min in an air atmosphere, pre-calcined for 6 hours, and then heated to 1550°C at the same heating rate and calcined for 8 hours, and then cooled to room temperature in the furnace, and then ground to obtain La2O3. 1.75 Mg(Al 0.25 W 0.25 Ta 0.5 )O6:0.005Mn 4+ Phosphor.

[0052] Example 9

[0053] Ethylene vinyl acetate was added to a toluene solution and dissolved under constant heating and stirring at 35°C until the entire solution became viscous, thereby obtaining an ethylene vinyl acetate solution. The phosphor of Example 3 was mixed with ethylene vinyl acetate at a mass ratio of 1:100 (1 wt%), and the mixture was spin-coated at a speed of 10,000 rpm to form a film. The film was then demolded to obtain a light-conversion film on an EVA substrate.

[0054] Example 10

[0055] The phosphor in Example 3 was mixed with epoxy resin (the mixing ratio of AB glue was 3:1) at a mass ratio of 1:20 (5 wt%), degassed using a vacuum degassing machine, poured into a mold, and placed in a drying oven at 60°C for 2 h. The mold was demolded to obtain a light-conversion film based on an epoxy resin matrix.

[0056] Example 11

[0057] Polyvinyl alcohol was added to deionized water and dissolved under constant heating and stirring at 95°C until the entire solution became viscous, thereby obtaining a polyvinyl alcohol solution. The phosphor of Example 3 was mixed with polyvinyl alcohol in a mass ratio of 1:10 (10 wt%), degassed using a vacuum degassing machine, poured into a mold, cast into a film, allowed to air-dry and solidify, and demolded to obtain a polyvinyl alcohol (PVA)-based light-conversion film.

[0058] Example 12

[0059] The phosphor in Example 4 was mixed with polypropylene in a mass ratio of 3:20 (15 wt%), put into an internal mixer for refining and mixing, crushed, pressed and formed by a film press, and demolded to obtain a light conversion film with a polypropylene (PP) matrix.

[0060] Example 13

[0061] The phosphor of Example 3 was mixed with a polysiloxane composition (in which polydimethylsiloxane and octamethylcyclotetrasiloxane were mixed in a mass ratio of 9:1) in a mass ratio of 1:5 (20 wt%), degassed using a vacuum degassing machine, poured into a mold, and placed in a drying oven at 80°C for 10 hours. The mold was demolded to obtain a light-conversion film based on a polysiloxane PDMS matrix.

[0062] Figure 1 The X-ray diffraction patterns of the phosphors synthesized in Examples 1 to 8 are compared with the standard data card. As shown in the figure, all the main diffraction peaks can correspond one-to-one with the standard data card, which indicates that a single phase was successfully synthesized.

[0063] Figure 2 The excitation and emission spectra of the phosphor synthesized in Example 2 are shown. As can be seen from the figure, at a monitoring wavelength of 706 nm, the excitation spectrum of this phosphor covers the range of 200-600 nm, effectively being excited by near-ultraviolet and some visible light. Under excitation at 455 nm, its emission spectrum exhibits deep red emission between 600 and 800 nm, with the optimal emission peak located near 706 nm.

[0064] Figure 3 The emission spectrum of the phosphor synthesized in Example 3 is similar to that of the photosensitive pigment P r and P frAnd the absorption spectrum comparison of chlorophyll a / b. It can be seen that its emission spectrum has obvious overlap with the absorption bands of chlorophyll and phytochrome in plant photosynthesis.

[0065] Figure 4 The water stability test results of the phosphor synthesized in Example 4 under 85°C / 85% H are shown. After 1000 hours of the "double 85" test, the phosphor can still maintain 98.9% of its initial integrated luminescence intensity, indicating its excellent water stability.

[0066] Figure 5 This is a diagram of the quantum efficiency of the phosphor synthesized in Example 5. Under 370nm excitation, the sample has an IQE of 85.2%, an Abs of 73.0%, and an EQE of 62.1%, demonstrating ultra-high internal and external quantum efficiencies.

[0067] Figure 6 and Figure 7 The following are the solar reflectance spectra of the polypropylene (PP)-based light-conversion film prepared in Example 12 and the polysiloxane (PDMS)-based light-conversion film prepared in Example 13. As can be seen, the light-conversion effect is significant, effectively converting ultraviolet light and a portion of visible light in sunlight into deep red light. The polysiloxane (PDMS)-based light-conversion film achieves a red-to-blue ratio of up to 3.96.

[0068] Figure 8 The experimental diagram of the polypropylene (PP)-based light-conversion film in Example 12 promoting the growth of lettuce, the standard error diagram of the dry and fresh weight, and the significance analysis are shown. After data comparison and analysis, in the lettuce growth experiment, both the fresh weight and dry weight of the experimental group (T) with a polypropylene (PP)-based light-conversion film laid around the lettuce were significantly improved compared with the blank group (CK). In the lettuce growth experiment, the fresh weight of a single plant increased by 79.22% compared with CK, and the dry weight increased by 61.41%.

[0069] Figure 9 Figure 12 shows the experimental results of the polypropylene (PP)-based light-conversion film promoting the growth of mini tomatoes, along with a standard error plot and significance analysis for both dry and fresh weight. Calculation and analysis of each data set revealed significant increases in both dry and fresh weight in the experimental group (T) compared to the control group (CK). In the mini-tomato growth experiment, the fresh weight per plant in the T group increased by 34.57% compared to the CK group, and the dry weight increased by 23.21%.

[0070] The above embodiments are only used to clearly illustrate the technical solutions of the present invention and are not intended to limit the implementation methods of the present invention. For those skilled in the art to which the present invention belongs, any modifications, equivalent substitutions, combinations, simplifications, and improvements made on the basis of and within the principles of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A Mn 4+ Activated deep red light emitting plant growth phosphor, characterized in that, Its chemical formula is La 2-2x-z A 2x Mg(Al 1 / 2-x-z W z ,Ta 1 / 2+x )O6:yMn 4+ , wherein A is one or more combinations of Ca, Sr, and Ba, the value range of x is 0≤x<1 / 2; the value range of y is 0<y≤0.3; the value range of z is 0≤z≤1 / 2; x+z≤1 / 2.

2. A Mn according to claim 1 4+ Activated deep red light emitting plant growth phosphor, characterized in that, The phosphor can be excited by near-ultraviolet and blue light at the same time, the excitation spectrum covers 200-600 nm, and the main emission peak is located between 600-800 nm.

3. A Mn according to any one of claims 1 to 2 4+ The method for preparing activated deep red light emitting phosphor for plant growth is characterized in that: The following steps are involved: S1, according to the chemical formula La 2-2x-z A 2x Mg(Al 1 / 2-x-z W z ,Ta 1 / 2+x )O6:yMn 4+ According to the stoichiometric ratio of each element in the mixture, accurately weigh the lanthanum-containing compound, the calcium-containing compound, the strontium-containing compound, the barium-containing compound, the magnesium-containing compound, the aluminum-containing compound, the tungsten-containing compound, the tantalum-containing compound and the manganese-containing compound, and fully grind and mix the weighed raw materials with the flux to obtain a mixture; S2. Place the mixture obtained in step 1 in an alumina crucible, heat it to 850-900°C at a heating rate of 5°C / min in an air atmosphere, pre-sinter for 3-6 hours, then heat it to 1450-1600°C and calcine for 6-8 hours, cool it to room temperature with the furnace, grind the product into powder, and prepare a deep red light-emitting phosphor for plant growth.

4. A Mn according to claim 3 4+ The method for preparing activated deep red light emitting phosphor for plant growth is characterized in that: In the step S1, The lanthanum-containing compound is one or more of La2O3, lanthanum-containing hydroxide, lanthanum-containing nitrate or lanthanum-containing carbonate; The calcium-containing compound is one or more of CaCO3, calcium-containing hydroxide, calcium-containing fluoride or calcium-containing oxide; The strontium-containing compound is one or more of SrCO3, strontium-containing nitrate, strontium-containing chloride or strontium-containing fluoride; The barium-containing compound is one or more of BaCO3, barium-containing chloride, barium-containing phosphate or barium-containing nitrate; The magnesium-containing compound is one or more of MgO, magnesium-containing hydroxide or magnesium-containing carbonate; The aluminum-containing compound is one or more of Al2O3, aluminum-containing phosphate or aluminum-containing hydroxide; The tungsten-containing compound is one or more of H2WO4, tungsten-containing oxides or tungsten-containing ammonium salts; The tantalum-containing compound is one or both of Ta2O5 and tantalum-containing hydroxide; The manganese-containing compound is one or more of MnCO3, manganese-containing acetate, manganese-containing oxalate, manganese-containing hydroxide or manganese-containing oxide; The flux is one or more of NH4Cl, Li2CO3, and H3BO3, and the amount of the flux added is 1-10 wt%.

5. The Mn according to claim 1 4+ Application of activated deep red light emitting phosphor for plant growth, characterized in that, The fluorescent powder is mixed with a polymer to prepare a light conversion film, which is used to supplement light for plants under sunlight and improve photosynthesis efficiency.

6. Mn according to claim 5 4+ Application of activated deep red light emitting phosphor for plant growth, characterized in that, The polymer is one or more of epoxy resin, polydimethylsiloxane, polypropylene, polyethylene, polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, ethylene vinyl acetate, polycarbonate, polystyrene, polyethylene terephthalate and polymethacrylate, and the phosphor mass proportion in the light conversion film is 1%-50%.

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