Blue fluorescent powder, preparation method thereof, LED lamp and application of LED lamp in plant growth lighting

Abstract

The application provides a blue fluorescent powder, a preparation method of the blue fluorescent powder, an LED lamp and application of the LED lamp in plant growth lighting. 8‑8x (SiO4)6O2:8xCe 3+ By replacing Ba ions or Gd ions by doping Ce ions, the blue fluorescence can be effectively generated without obviously changing the lattice shape, the fluorescence intensity and the wavelength range of the blue fluorescence effectively cover the absorption range of chlorophyll A and chlorophyll B in the blue light band, and the photosynthesis efficiency of plants is greatly improved.

Description

Technical field

[0001] The present invention belongs to the field of fluorescent powder, and in particular relates to a blue fluorescent powder and a preparation method thereof, an LED lamp and an application thereof in plant growth lighting. [Background Technology]

[0002] The essence of crop growth is the synthesis of organic matter through light reactions, and the total amount of organic matter synthesized by light reactions must be greater than the total amount of organic matter consumed by dark reactions. In order to achieve rapid growth of crops, supplementary lighting for crops at night is currently an important means of crop cultivation.

[0003] On the other hand, it is well known that plants exposed to light for a long time may be damaged, which may inhibit the growth of the plants. At present, there is a lack of a suitable light source that can ensure the normal growth of plants even if the plants are illuminated for a long time. [Summary of the invention]

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a blue phosphor and a preparation method thereof, an LED lamp and an application thereof in plant growth lighting.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A blue phosphor with the chemical formula Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ .

[0007] In the present invention, x=0.07.

[0008] A method for preparing blue phosphor, comprising: mixing BaCO3, Gd2O3, SiO2 and CeO2 to form a blue phosphor. 8-8x (SiO4)6O2:8xCe 3+ The mixture is sintered in a reducing atmosphere and then cooled to form Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ .

[0009] The sintering temperature of the present invention is 1450°C.

[0010] A blue phosphor with the chemical formula Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ .

[0011] In the present invention, y=0.05.

[0012] A method for preparing blue phosphor, comprising: mixing BaCO3, Gd2O3, SiO2 and CeO2 in a Ba2-2y Gd8(SiO4)6O2:2yCe 3+ The mixture is sintered in a reducing atmosphere and then cooled to form Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ .

[0013] An LED lamp includes a NUV chip and blue phosphor.

[0014] The invention discloses an application of an LED lamp in plant growth lighting.

[0015] The current of the NUV chip of the present invention is 160mA-170mA.

[0016] The beneficial effects of the present invention are:

[0017] The present invention takes the hexagonal system formed by Ba2Gd8(SiO4)6O2 as the basis, and 8-8x (SiO4)6O2:8xCe 3+ Or Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ Under the conditions of the general chemical formula, by replacing Ba ions or Gd ions with Ce ions, blue fluorescence can be effectively produced without significantly changing the lattice shape. The fluorescence intensity and wavelength range of this blue fluorescence effectively cover the absorption range of chlorogreen A and chlorogreen B in the blue light band, greatly improving the photosynthesis efficiency of plants.

[0018] When plants are supplemented with LED lights made from the above-mentioned blue fluorescent powder, the effect of improving their photosynthesis efficiency is significantly stronger than the adverse effects of long-term light exposure on the plants, and can effectively increase the growth rate of the plants.

[0019] In addition, within the tolerance current range of the NUV chip, there is a good positive correlation between the luminous intensity of the LED lamp and the power-on current of the NUV chip, which gives the LED lamp a larger adjustable range of luminous intensity.

[0020] Other features and advantages of the present invention will be disclosed in detail in the following specific embodiments and drawings.

Brief Description of the Drawings

[0021] Figure 1 This is the lattice diagram of Ba2Gd8(SiO4)6O2;

[0022] Figure 2 Ba2Gd in Examples 1-6 of the present invention 8-8x (SiO4)6O2:8xCe 3+ XRD pattern of

[0023] Figure 3 Ba in Examples 7-12 of the present invention 2-2y Gd8(SiO4)6O2:2yCe 3+ XRD pattern of

[0024] Figure 4 Ba2Gd in Examples 1-6 of the present invention 8-8x (SiO4)6O2:8xCe 3+ PL and PLE spectra of

[0025] Figure 5 Ba in Examples 7-12 of the present invention 2-2y Gd8(SiO4)6O2:2yCe 3+ PL and PLE spectra;

[0026] Figure 6 1 is a comparison chart of the fluorescence intensity of the blue phosphors in Example 4 and Example 10 of the present invention;

[0027] Figure 7 chromaticity diagram of the blue phosphor in Example 4 and Example 10 of the present invention;

[0028] Figure 8 Ba2Gd in Example 4 of the present invention 8-8x (SiO4)6O2:8xCe 3+ Emission spectra at different temperatures;

[0029] Figure 9 Ba in Example 10 of the present invention 2-2y Gd8(SiO4)6O2:2yCe 3+ Emission spectra at different temperatures;

[0030] Figure 10 This is a temperature test diagram of the LED lamp at different currents in Example 13 of the present invention;

[0031] Figure 11 This is a temperature test diagram of the LED lamp at different currents in Example 14 of the present invention;

[0032] Figure 12 This is a graph showing the emission spectra of the LED lamp at different currents in Example 13 of the present invention;

[0033] Figure 13 This is a graph showing the emission spectra of the LED lamp at different currents in Example 14 of the present invention;

[0034] Figure 14 This is a comparison diagram of the emission spectrum of the LED lamp and the absorption spectrum of the pigment in Example 13 of the present invention;

[0035] Figure 15 This is a comparison chart of the emission spectrum of the LED lamp and the absorption spectrum of the pigment in Example 14 of the present invention;

[0036] Figure 16 These are photos of the growth of Pothos sinensis under different light conditions over 7 days;

[0037] Figure 17 The weight change curve of green radish under different light conditions within 19 days:

[0038] Figure 18 The linear fitting curve of the weight change of Scindapsus radish under different light conditions within 19 days. [Specific implementation method]

[0039] The following is an explanation and description of the technical solutions of the embodiments of the present invention in conjunction with the drawings of the embodiments of the present invention. However, the following embodiments are only preferred embodiments of the present invention and are not exhaustive. Based on the embodiments in the implementation manner, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0040] In the following description, terms such as "inside", "outside", "up", "down", "left", "right", etc. that indicate directions or positional relationships are only used to facilitate the description of the embodiments and simplify the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, they should not be understood as limiting the present invention.

[0041] See also Figure 1 , Ba2Gd8(SiO4)6O2 is a hexagonal crystal system. Si 4+ With 4 O 2- Coordinate to form [SiO4] polyhedron, Ba 2+ and Gd 3+ There are two low-symmetry cationic sites, namely C s Point-symmetric 9-coordinated 4f sites and C s The idea of ​​the present invention is to use Ce 3+ Right 2+ or Gd 3+ Replacement is carried out to produce appropriate transition energy levels, thereby emitting appropriate fluorescence in the blue light band, which greatly promotes plant growth.

[0042] Example 1:

[0043] This embodiment provides a blue phosphor with the chemical formula of Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ .

[0044] The preparation method of blue phosphor is as follows: BaCO3, Gd2O3, SiO2 and CeO2 are mixed into Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ The mixture was sintered at 1450℃ in a reducing atmosphere and then cooled to form Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ .

[0045] In this embodiment, x=0.01.

[0046] Example 2:

[0047] The difference between this embodiment and embodiment 1 is that x=0.03.

[0048] Example 3:

[0049] The difference between this embodiment and embodiment 1 is that x=0.05.

[0050] Example 4:

[0051] The difference between this embodiment and embodiment 1 is that x=0.07.

[0052] Example 5:

[0053] The difference between this embodiment and embodiment 1 is that x=0.09.

[0054] Example 6:

[0055] The difference between this embodiment and embodiment 1 is that x=0.11.

[0056] Example 7:

[0057] This embodiment provides a blue phosphor, the chemical formula of which is Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ .

[0058] The preparation method of blue phosphor is as follows: BaCO3, Gd2O3, SiO2 and CeO2 are mixed in a Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ The mixture is sintered at 1450℃ in a reducing atmosphere and then cooled to form Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ .

[0059] In this embodiment, y=0.005.

[0060] Example 8:

[0061] The difference between this embodiment and embodiment 7 is that y=0.01.

[0062] Example 9:

[0063] The difference between this embodiment and embodiment 7 is that y=0.03.

[0064] Example 10:

[0065] The difference between this embodiment and embodiment 7 is that y=0.05.

[0066] Example 11:

[0067] The difference between this embodiment and embodiment 7 is that y=0.07.

[0068] Example 12:

[0069] The difference between this embodiment and embodiment 7 is that y=0.09.

[0070] See also Figure 2 and Figure 3 , JCPDS#28-1220 is the XRD pattern of Ba2Gd8(SiO4)6O2, where x is in the range of 0-0.11, Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ The XRD of Ba2Gd8(SiO4)6O2 has no obvious impurity peaks, and y is in the range of 0-0.09. 2-2y Gd8(SiO4)6O2:2yCe 3+ The XRD of Ba2Gd8(SiO4)6O2 also did not produce obvious impurity peaks, indicating that the Ce 3+ Right 2+ or Gd 3+ The substitution will not significantly destroy the hexagonal crystal structure.

[0071] See also Figure 4 ,Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ The emission wavelength is 432 nm and the excitation wavelength is 369 nm.

[0072] See also Figure 5 , Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ The emission wavelength is 428 nm and the excitation wavelength is 351 nm.

[0073] Combine Figure 4 、 Figure 5 and Figure 7 , it can be proved that Ba2Gd 8-8x(SiO4)6O2:8xCe 3+ and Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ When excited by ultraviolet light, it emits blue light. The reason is that Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ and Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ It has a special energy level structure. The generation of this energy level structure is on the one hand Ce 3+ On the other hand, Ce 3+ Doped Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ and Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ Still maintains the hexagonal crystal system.

[0074] Ba2Gd in Examples 1-6 8-8x (SiO4)6O2:8xCe 3+ The normalized fluorescence intensities are shown in Table 1.

[0075] Table 1

[0076] x 0.01 0.03 0.05 0.07 0.09 0.11 Normalized fluorescence intensity (%) 100 217.3 286.8 333.2 261.4 221.9

[0077] In Example 4, when x=0.07, Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ The fluorescence intensity reaches the maximum value.

[0078] Ba in Examples 7-12 2-2y Gd8(SiO4)6O2:2yCe 3+ The normalized fluorescence intensities are shown in Table 2.

[0079] Table 2

[0080] y 0.005 0.01 0.03 0.05 0.07 0.09 Normalized fluorescence intensity (%) 100 107.3 174.0 238.2 235.1 190.6

[0081] In Example 10, when x=0.05, Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ The fluorescence intensity reaches the maximum value.

[0082] See also Figure 6 , Ba2Gd in Example 4 8-8x (SiO4)6O2:8xCe 3+ The fluorescence intensity of Ba is significantly greater than that of Ba in Example 10. 2-2y Gd8(SiO4)6O2:2yCe3+ This is mainly due to two reasons. First, Gd 3+ and Ce 3+ The valence of Ba is the same, and 2+ With Ce 3+ The valence of Ce is different, which leads to 3+ In the Ba 2+ When the substitution is carried out, defects are generated, which form luminescence quenching centers, reducing the luminescence intensity to a certain extent. Secondly, Ba 2+ The ionic radius and Ce 3+ The ionic radius of Gd 3+ and Ce 3+ The ionic radius of Ce is similar, so 3+ In the Ba 2+ When replaced, compared to Ce 3++ Replace Gd 3+ In the case of Ce, the crystal structure has a more obvious impact. Combining the two reasons, it can be found that Ce 3+ Replace Gd 3+ The formed Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ , compared with Ce 3+ Replace Ba 2+ The formed Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ In terms of their luminescence mechanisms, there are considerable differences.

[0083] Among them 2+ When the coordination number is 7, the ionic radius is Ba 2+ When the coordination number is 9, the ionic radius is Gd 3+ When the coordination number is 7, the ionic radius is Gd 3+ When the coordination number is 9, the ionic radius is Ce 3+ When the coordination number is 7, the ionic radius is Ce 3+ When the coordination number is 9, the ionic radius is

[0084]

[0085] In order to illuminate plants for a long time, a lot of heat will be generated during the lighting process, so the thermal effect will affect the Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ and Ba 2-2y Gd8(SiO4)6O2:2yCe 3+The influence of luminescence stability cannot be ignored.

[0086] For this purpose, the Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ The relationship between the fluorescence intensity and temperature is shown in Table 3 and Figure 8 shown.

[0087] Table 3

[0088]

[0089] In Example 10, Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ The relationship between the fluorescence intensity and temperature is shown in Table 4 and Figure 9 shown.

[0090] Table 4

[0091]

[0092]

[0093] Contrary to the fluorescence intensity comparison results, Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ The thermal stability of the fluorescence intensity is relatively stable compared with Ba2Gd in Example 4. 8-8x (SiO4)6O2:8xCe 3+ The fluorescence intensity and thermal stability are better.

[0094] Comparative Example 10 2-2y Gd8(SiO4)6O2:2yCe 3+ and Ba2Gd in Example 4 8-8x (SiO4)6O2:8xCe 3+ The fluorescence intensity ratios of the two at different temperatures are shown in Table 5. 2-2y Gd8(SiO4)6O2:2yCe 3+ Fluorescence intensity of Ba2Gd in Example 4 8-8x (SiO4)6O2:8xCe 3+ The fluorescence intensity.

[0095] Table 5

[0096]

[0097] It is not difficult to see that as the temperature rises, Ba 2-2y Gd8(SiO4)6O2:2yCe 3+and Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ The fluorescence intensity difference between the two groups gradually narrowed, but overall 2-2y Gd8(SiO4)6O2:2yCe 3+ The fluorescence intensity of Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ In other words, the fluorescence intensity of Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ More suitable for plant lighting.

[0098] To prove that 2-2y Gd8(SiO4)6O2:2yCe 3+ and Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ It can be used as an auxiliary light source during plant growth, and additional embodiments 13 and 14 are provided.

[0099] Example 13:

[0100] This embodiment provides an LED lamp, including a NUV chip and a Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ of blue phosphor.

[0101] Example 14:

[0102] This embodiment provides an LED lamp, including a NUV chip and a chemical formula of Ba in embodiment 10. 2-2y Gd8(SiO4)6O2:2yCe 3+ of blue phosphor.

[0103] See also Figure 10 and Figure 11 As the current through the NUV chip increases, the temperature of the LED lamps in Example 13 and Example 14 both begin to increase. However, at the same current, the temperature rise rate of the LED lamp in Example 13 is significantly slower than that of the LED lamp in Example 14. This difference indirectly reduces the sensitivity of the LED lamp to Ba2Gd 8-8x (SiO4)6O2:8xCe 3+ Requirements for thermal stability of luminous intensity.

[0104] See also Figure 12 and Figure 13Although the luminous intensity of the blue phosphor in the LED lamps of Examples 13 and 14 decreases as the current increases, the NUV chip's increased power effectively offsets this adverse effect, significantly improving the LED lamp's luminous intensity. Of particular note, every 20mA increase in current significantly increases the LED lamp's luminous intensity. This indicates that as long as the current exceeds 160mA, the LED lamp's luminous intensity still has significant room for improvement. This demonstrates that, at the rated current of the NUV chip, the LED lamps of Examples 13 and 14 have a wider adjustable luminous power range.

[0105] The photosynthesis of plants mainly depends on Chlorophyll A (chlorophyll a), Chlorophyll B (chlorophyll b), R 、P FR These four pigments mainly absorb blue and red light. Figure 14 and Figure 15 The emission spectra of the LED lamps in Examples 13 and 14 effectively cover the blue wavelength band of the aforementioned pigment. On the other hand, when the current is 160 mA, the emission spectrum of the LED lamps already nearly fully covers the blue wavelength band of the aforementioned pigment. Therefore, further increasing the current would not only increase power consumption but would likely fail to further promote plant growth. Therefore, the operating current of the LED lamps in Examples 13 and 14 is preferably limited to the range of 160 mA-170 mA.

[0106] Combined with the above analysis, it can at least be proved that the LED lamp in Example 13 is more suitable for use as a plant growth lamp than the LED lamp in Example 14.

[0107] Based on this, this embodiment uses the LED lamp in Example 13 to conduct a 7-day growth test experiment on the green radish.

[0108] See also Figure 16 The photos of the first row of green radish are growth photos from the first day to the seventh day in a completely dark environment, and are only exposed to light when taking pictures; the photos of the second row of green radish are exposed to light conditions from the first day to the seventh day, using natural light during the day and keeping it dark at night; the photos of the third row of green radish are exposed to light conditions from the first day to the seventh day, using natural light during the day and using the LED light in Example 13 at night.

[0109] The weight changes of the three rows of green radish in 19 days are shown in Figure 17 and Table 6.

[0110] Table 6

[0111]

[0112] After 19 days in total darkness, the weight of the green radish decreased by 1.233 g. After 19 days of exposure to natural light during the day and darkness at night, the weight of the green radish increased by approximately 0.475 g. After 19 days of exposure to natural light during the day and the LED light of Example 13 at night, the weight of the green radish increased by as much as 0.794 g.

[0113] Combine Figure 18 It is not difficult to find that the dark reaction rate of the green radish is roughly constant under the conditions of full darkness within 19 days. At the same time, the weight growth rate of the green radish is also roughly unchanged under the conditions of daylight and night darkness within 19 days. This shows that under these conditions, the light reaction rate of the green radish not only covers the material consumption of its dark reaction, but also its light reaction rate is constant. Further, the weight growth rate of the green radish under the conditions of daylight and night LED lighting within 19 days is higher than the growth rate of the green radish under the conditions of daylight and night darkness, and the growth rate is always relatively constant. This shows that the use of the LED lamp in Example 13 to supplement the light of the green radish at night not only ensures that the growth rate of the green radish is accelerated, but also the effect of improving the growth rate is relatively constant. Even after long-term irradiation, there is no obvious adverse effect on the metabolism of the green radish. One of the important reasons is that the emission spectrum of the LED lamp has a strong adaptability to the absorption spectrum of the photosynthetic pigment.

[0114] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art will understand that the present invention includes, but is not limited to, the contents described in the drawings and the above specific embodiments. Any modifications that do not deviate from the functional and structural principles of the present invention are intended to be included within the scope of the claims.

Claims

1. A blue phosphor, characterized in that: The chemical formula is Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ , y=0.

05.

2. A method for preparing the blue phosphor according to claim 1, characterized in that: BaCO3, Gd2O3, SiO2 and CeO2 were prepared by Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ The mixture is formed by mixing the two materials in a ratio of y = 0.05, sintering in a reducing atmosphere and then cooling to form Ba 2-2y Gd8(SiO4)6O2:2yCe 3+ .

3. An LED lamp, characterized in that: The invention comprises a NUV chip and the blue phosphor as claimed in claim 1.

4. Use of the LED lamp according to claim 3 in plant growth lighting.

5. The application of the LED lamp in plant growth lighting according to claim 4, characterized in that: The NUV chip's current is 160mA-170mA.

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