Red fluorescent powder for plant growth and preparation method thereof

Abstract

The application discloses a red fluorescent powder for plant growth, which has a chemical general formula of Ba2LuNb 1‑0.8x Mn x O6,0

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic materials, in particular to a red fluorescent powder for plant growth and a preparation method thereof BACKGROUND

[0002] People are increasingly meticulous about controlling the growth environment and lighting conditions of plants in order to achieve higher growth efficiency and yield. Plant photosynthesis mainly relies on blue-green light and red light in sunlight, and these two wavelengths of light are most effective for plant photosynthesis. However, the actual planting conditions often cannot always provide sufficient and suitable light.

[0003] Fluorescent materials can absorb light of a specific wavelength and convert it into a specific light wavelength required by plants, especially red light, which is particularly crucial for plant growth in the dark or low-light environment. Among fluorescent materials, red fluorescent powder can emit a spectrum that matches the red light required for plant photosynthesis, effectively promoting plant photosynthesis and improving growth speed and yield.

[0004] Currently reported red fluorescent powders are mainly activated by Cr 3+ ion-activated oxides and Sm 3+ ion-activated oxides. The emission peak of such fluorescent powders is relatively sharp and is not suitable for the wide spectrum required for plant growth. In addition, such fluorescent powders are usually obtained by high-temperature solid-phase method, which has high energy consumption, and during the preparation process, foreign phases are often introduced, resulting in uneven and severely aggregated fluorescent powder particles, which causes low luminous efficiency. SUMMARY

[0005] In view of the above technical defects of the prior art, the present application aims to provide a red fluorescent powder for plant growth and a preparation method thereof, with the aim of improving the emission bandwidth of the material in the range of 600-750 nm.

[0006] The technical solution of the present application is as follows:

[0007] A red fluorescent powder for plant growth, with a chemical formula of Ba2LuNb 1-0.8x Mn x O6, 0 < x ≤ 0.2.

[0008] Another technical solution of the present application is as follows:

[0009] A preparation method of a red fluorescent powder for plant growth, comprising the following steps:

[0010] According to the fluorescent powder chemical formula Ba2LuNb 1-0.8x Mn xThe stoichiometric ratio of each element required in 0.6, 0

[0011] The barium carbonate, the lutetium oxide, the niobium pentoxide and the manganese carbonate powder are dissolved in nitric acid to form a mixture;

[0012] The water of the mixture is heated to evaporate, and then heated to 400-500 DEG C for sintering;

[0013] After the sintered product is cooled to room temperature, ball milling is carried out, and the temperature during the ball milling is 600-800 DEG C, and then the product is cooled to room temperature to obtain the red fluorescent powder for plant growth.

[0014] Further, the sintering is carried out at 400-500 DEG C, and the temperature is raised to 400-500 DEG C at a temperature raising speed of 5-10 DEG C / min.

[0015] Further, the sintering is carried out at 400-500 DEG C for 2-4 h.

[0016] Further, the ball-to-material ratio during the ball milling is 15:1-30:1.

[0017] Further, the ball milling speed during the ball milling is 200-500 r / min.

[0018] Further, the ball milling time during the ball milling is 1-3 h.

[0019] The Mn 4+ is doped into the center position of the [NbO6] octahedron, and the 3d electron group state in the octahedral crystal field can be split into three degenerate states T 2g and two degenerate states E g The red emission is derived from the spin-forbidden transition of the electron 2 E g → 4 A 2g , and the gap between the two energy levels after the orbital splitting helps the Mn 4+ to be stabilized in the tetravalent state, and the finally obtained Mn 4+ ion doped niobate fluorescent powder has the characteristics of high stability, good luminescent performance and low cost.

[0020] Compared with the prior art, the present application has the following advantages:

[0021] 1. The fluorescent powder takes Mn 4+ as the luminescent center, presents a very strong wide peak excitation in the range of 250-550 nm, and the emission peak range is between 600-750 nm, which can be well matched with the ultraviolet and blue LED chips, and is suitable for the wavelength range required by the plant growth illumination.

[0022] 2. The raw material mixture is dissolved in dilute nitric acid, which allows the elements to achieve uniform mixing at the atomic level. This promotes the reaction of the raw materials, significantly reduces the reaction temperature during ball milling, improves crystallinity, thereby enhancing the optical properties of the phosphor, and the obtained phosphor has a uniform particle size distribution with approximately spherical grains.

[0023] 3. Compared to rare earth element Eu, manganese carbonate (Mn) has a lower cost. 4+ Doped niobate phosphors have a superior cost advantage. Attached Figure Description

[0024] Figure 1 This is a SEM image of the red fluorescent powder for plant growth prepared in Example 1.

[0025] Figure 2 The excitation spectrum of the red phosphor for plant growth prepared in Example 2 is shown.

[0026] Figure 3 The emission spectrum of the red phosphor for plant growth prepared in Example 3 is shown. Detailed Implementation

[0027] The present invention will be further described below with reference to embodiments, but these are not intended to limit the scope of the invention.

[0028] Example 1

[0029] 39.4 g of barium carbonate, 19.9 g of lutetium oxide, 12.768 g of niobium pentoxide, and 0.575 g of manganese carbonate powder were weighed and dissolved in 2M dilute nitric acid. The product, after evaporating the aqueous solution, was heated to 400°C at a rate of 8°C / min and pre-calcined for 3 hours. After pre-calcination, the product was cooled to room temperature and then placed in a high-purity zirconia jar and ball-milled in a high-temperature ball mill using zirconia balls for 2 hours. The ball-milling temperature was 700°C, the ball-to-material ratio was 30:1, and the ball-milling speed was 300 r / min. After ball milling, the product was cooled to room temperature to obtain the red fluorescent powder Ba2LuNb for plant growth. 0.96 Mn 0.05 O6, from Figure 1 The SEM images show that the phosphor particles are uniformly dispersed without agglomeration, and the crystals are approximately spherical.

[0030] Example 2

[0031] 39.4 g of barium carbonate, 19.9 g of lutetium oxide, 12.236 g of niobium pentoxide, and 1.15 g of manganese carbonate powder were weighed and dissolved in 3M dilute nitric acid. The product, after evaporating the aqueous solution, was heated to 500°C at a rate of 10°C / min and pre-calcined for 2 hours. After pre-calcination, the product was cooled to room temperature and then placed in a high-purity zirconia jar and ball-milled in a high-temperature ball mill using zirconia balls for 1 hour. The ball-milling temperature was 800°C, the ball-to-material ratio was 20:1, and the ball-milling speed was 400 r / min. After ball milling, the product was cooled to room temperature to obtain the red fluorescent powder Ba2LuNb for plant growth. 0.92 Mn 0.1 O6 was used to perform fluorescence spectroscopy on the obtained phosphor. The excitation spectrum was measured at a monitoring wavelength of 684 nm. The test results are as follows: Figure 2 It can be seen that: phosphors are mainly composed of Mn 4+ As the light-emitting center, it exhibits a strong broad peak excitation in the 250–550 nm range, which can be well matched with ultraviolet and blue LED chips.

[0032] Example 3

[0033] 39.4 g of barium carbonate, 19.9 g of lutetium oxide, 11.704 g of niobium pentoxide, and 1.725 g of manganese carbonate powder were weighed and dissolved in 4M dilute nitric acid. The product, after evaporating the aqueous solution, was heated to 450°C at a rate of 9°C / min and pre-calcined for 2 hours. After pre-calcination, the product was cooled to room temperature and then placed in a high-purity zirconia jar and ball-milled for 3 hours using zirconia balls in a high-temperature ball mill. The ball milling temperature was 600°C, the ball-to-material ratio was 15:1, and the ball milling speed was 500 r / min. After ball milling, the product was cooled to room temperature to obtain the red fluorescent powder Ba2LuNb for plant growth. 0.88 Mn 0.15 O6 was used to perform fluorescence spectroscopy on the obtained phosphor. The emission spectrum was measured with 352 nm as the excitation wavelength. The test results are as follows: Figure 3 It can be seen that the phosphor exhibits broadband emission in the range of 600-750nm, which is suitable for the wavelength range of light required for plant growth.

[0034] Comparative Example 1

[0035] 39.4 g of barium carbonate, 19.9 g of lutetium oxide, 12.768 g of niobium pentoxide, and 0.575 g of manganese carbonate powder were weighed and dissolved in 2M dilute nitric acid. After heating and evaporating the aqueous solution, the product was heated to 300°C at a heating rate of 8°C / min and pre-calcined for 2 hours. After pre-calcination, the product was cooled to room temperature and then placed in a high-purity zirconia jar and ball-milled in a high-temperature ball mill using zirconia balls for 2 hours. The ball-milling temperature was 700°C, the ball-to-material ratio was 30:1, and the ball-milling speed was 300 r / min. After ball milling, the product was cooled to room temperature to obtain phosphor. The results showed that the obtained phosphor had a significantly smaller grain size and a significantly lower luminescence intensity compared to that of Example 1.

[0036] Comparative Example 2

[0037] 39.4 g of barium carbonate, 19.9 g of lutetium oxide, 12.236 g of niobium pentoxide, and 1.15 g of manganese carbonate powder were weighed and dissolved in 3M dilute nitric acid. The product, after being heated to dryness of the aqueous solution, was heated to 500°C at a heating rate of 10°C / min and pre-calcined for 2 hours. After pre-calcination, the product was cooled to room temperature and then placed in a high-purity zirconia jar and ball-milled in a high-temperature ball mill using zirconia balls for 1 hour. The ball-milling temperature was 500°C, the ball-to-material ratio was 20:1, and the ball-milling speed was 400 r / min. After ball milling, the product was cooled to room temperature to obtain phosphor. The results showed that the obtained phosphor contained impurity peaks and could not obtain a pure phase. Compared with Example 2, its luminescence performance was also significantly reduced.

Claims

1. A method for preparing a red fluorescent powder for plant growth, characterized by, According to the general formula of the fluorescent powder Ba2LuNb 1-0.8x Mn x The stoichiometric ratio of each element required in the formula of Ba2LuNbO6, 0 < x < 0.2 is weighed with barium carbonate, lutetium oxide, niobium pentoxide and manganese carbonate powder. The barium carbonate, lutetium oxide, niobium pentoxide and manganese carbonate powder are dissolved in nitric acid to form a mixture; The water of the mixture is evaporated by heating, and then the mixture is heated to 400-500°C for firing; The fired product is cooled to room temperature, and then ball-milled at a ball-to-material ratio of 15:1-30:1 and a temperature of 600-800°C, and then cooled to room temperature to obtain the red fluorescent powder for plant growth.

2. The method for preparing red fluorescent powder for plant growth according to claim 1, characterized in that, The temperature is raised to 400-500°C at a temperature raising rate of 5-10°C / min.

3. The method for preparing red fluorescent powder for plant growth according to claim 2, characterized in that, The firing is performed at 400-500°C for 2-4h.

4. The method for preparing red fluorescent powder for plant growth according to claim 1, characterized in that, The ball-milling speed is 200-500r / min.

5. The method for preparing red fluorescent powder for plant growth according to claim 1, characterized in that, The ball-milling time is 1-3h.

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