CN117821057A - Borate blue luminous fluorescent powder suitable for near ultraviolet excitation, preparation method thereof and warm white light LED device - Google Patents
Borate blue luminous fluorescent powder suitable for near ultraviolet excitation, preparation method thereof and warm white light LED device Download PDFInfo
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- 239000000843 powder Substances 0.000 title claims abstract description 147
- 230000005284 excitation Effects 0.000 title claims abstract description 51
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 title claims abstract description 35
- 238000002360 preparation method Methods 0.000 title abstract description 13
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000012535 impurity Substances 0.000 claims abstract description 12
- 239000000126 substance Substances 0.000 claims abstract description 11
- 238000000034 method Methods 0.000 claims abstract description 10
- 238000001354 calcination Methods 0.000 claims description 38
- 238000000227 grinding Methods 0.000 claims description 30
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 24
- 238000001816 cooling Methods 0.000 claims description 21
- 239000002994 raw material Substances 0.000 claims description 16
- 238000002156 mixing Methods 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 11
- 238000003825 pressing Methods 0.000 claims description 11
- 238000002791 soaking Methods 0.000 claims description 11
- 150000001875 compounds Chemical class 0.000 claims description 9
- 238000005406 washing Methods 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 7
- 229910052796 boron Inorganic materials 0.000 claims description 6
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 claims description 6
- 229910004283 SiO 4 Inorganic materials 0.000 claims description 4
- 239000004065 semiconductor Substances 0.000 claims description 4
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 3
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 3
- 239000004327 boric acid Substances 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 3
- 229910000000 metal hydroxide Inorganic materials 0.000 claims description 3
- 229910044991 metal oxide Inorganic materials 0.000 claims description 3
- 150000004706 metal oxides Chemical class 0.000 claims description 3
- 238000010521 absorption reaction Methods 0.000 abstract description 9
- 238000009877 rendering Methods 0.000 abstract description 5
- 230000008569 process Effects 0.000 abstract description 3
- 230000007613 environmental effect Effects 0.000 abstract description 2
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- 239000000463 material Substances 0.000 abstract description 2
- 230000015572 biosynthetic process Effects 0.000 abstract 1
- 238000003786 synthesis reaction Methods 0.000 abstract 1
- 229910052593 corundum Inorganic materials 0.000 description 16
- 239000010431 corundum Substances 0.000 description 16
- 238000010306 acid treatment Methods 0.000 description 11
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 8
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- 238000010438 heat treatment Methods 0.000 description 7
- 238000000295 emission spectrum Methods 0.000 description 5
- 238000000695 excitation spectrum Methods 0.000 description 5
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- 108010043121 Green Fluorescent Proteins Proteins 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 239000003086 colorant Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000001194 electroluminescence spectrum Methods 0.000 description 2
- 239000011812 mixed powder Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
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Abstract
The invention relates to the field of luminescent materials, and discloses borate blue luminescent fluorescent powder suitable for near ultraviolet excitation, a preparation method thereof and a warm white light LED device, wherein the fluorescent powder has a chemical formula of LiNa 2 Sr 8‑x B 12 O 24 F 6 Cl:xEu 2+ (0 < x +.0.03); the fluorescent powder has strong absorption in the wave band of 350-400 nm, can be effectively excited by near ultraviolet light, and emits high-color purity blue light with dominant wavelength of 470 nm. After the fluorescent powder is soaked in low-concentration hydrochloric acid to remove impurities, the luminous intensity and the quantum efficiency of the fluorescent powder are obviously improved. The fluorescent powder keeps high-intensity emission in a high-temperature environment, and shows excellent thermal stability; the fluorescent powder has the advantages of low synthesis temperature, simple process, low cost and environmental friendliness, and is suitable for industrial production. The excellent comprehensive performance can enable the fluorescent powder to be mixed with other color fluorescent powder, and the fluorescent powder is driven by a near ultraviolet chipAnd obtaining the warm white light LED device with high color rendering index and moderate color temperature.
Description
Technical Field
The invention belongs to the technical field of luminescent materials, and particularly relates to borate blue luminescent fluorescent powder suitable for near ultraviolet excitation, a preparation method thereof and a warm white light LED device.
Background
Advanced lighting and backlighting devices are becoming increasingly popular worldwide. Phosphor converted light emitting diodes (pc-LEDs) are of great interest because of their low power consumption, long lifetime and low manufacturing costs. In indoor lighting applications, warm White Light Emitting Diodes (WLEDs) are considered to be more competitive future light sources than incandescent and compact fluorescent lamps, which have many unparalleled advantages such as high efficiency, energy conservation, long life, and environmental reliability.
Currently, the dominant approach for commercial white LEDs is by incorporating a yellow phosphor (YAG: ce 3+ ) When the white light is coated on an InGaN blue light chip, a part of blue light emitted by the blue light chip and yellow light emitted by yellow fluorescent powder excited by the blue light chip obtain white light, but due to the lack of green light and red light components in a white light spectrum obtained by the scheme, the color rendering index of the white light spectrum is lower (Ra < 80), the correlated color temperature is higher (CCT > 7000), and the pursuit of people on high-quality LEDs cannot be met. To solve the problems of blue light chip and yellow fluorescent powder (YAG: ce) 3+ ) The problems caused by the combination of white light are solved, researchers start to use near ultraviolet chips to combine red, green and blue three-primary color fluorescent powder to obtain white light, and the proposal requires that the red, green and blue three-color fluorescent powder has strong absorption in the ultraviolet region and high-efficiency luminescence in the visible light region. Therefore, how to realize the white light LED by exciting the mixed fluorescent powder of the three primary colors of red, green and blue through near ultraviolet light has become a hot spot for research at home and abroad. The development of blue suitable for near ultraviolet excitation is the key of the strategy of combining red, green and blue three-primary-color fluorescent powder with near ultraviolet chip to obtain white light. Therefore, development of blue-emitting phosphors excellent in combination properties has become one of the key points in obtaining a high-efficiency LED device.
Disclosure of Invention
In order to solve the problems in the prior art, the invention aims to provide borate blue luminescent fluorescent powder suitable for near ultraviolet excitation, a preparation method thereof and a warm white light LED device. The fluorescent powder has strong absorption in the near ultraviolet region and excellent thermal stability, and can meet the requirement of blue emission with high color purity excited by the near ultraviolet light.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a borate blue luminous fluorescent powder suitable for near ultraviolet excitation has the following chemical formula:
LiNa 2 Sr 8-x B 12 O 24 F 6 Cl:xEu 2+ wherein x is Eu 2+ Substituted Sr 2+ The range of the molar ratio of x is as follows: and 0 < x is less than or equal to 0.03.
The preparation method of the borate blue luminous fluorescent powder suitable for near ultraviolet excitation comprises the following steps:
uniformly mixing raw material powder of borate blue luminous fluorescent powder suitable for near ultraviolet excitation to obtain a raw material mixture;
presintering the raw material mixture at 200-500 ℃ for 2-6 hours, cooling to room temperature after presintering, grinding into powder and uniformly mixing to obtain an intermediate;
pressing the intermediate into a sheet-like shaped body;
the sheet-shaped formed body is subjected to primary calcination, natural cooling and grinding are carried out after the primary calcination is finished, the ground powder is subjected to secondary calcination, and natural cooling and grinding are carried out after the secondary calcination is finished; the calcination conditions of the primary calcination and the secondary calcination are the same, the temperature during the calcination is 650-750 ℃, the time is 4-8 h, and the atmosphere is a reducing atmosphere;
and (3) soaking the powder obtained by secondary calcination and grinding in hydrochloric acid solution to remove impurities, and separating, washing and drying after the soaking and the impurity removal are finished to obtain the borate blue luminescent fluorescent powder suitable for near ultraviolet excitation.
Preferably, the borate blue light-emitting fluorescent powder is prepared from a compound containing Li, na, sr, B, F, cl and Eu elements.
Preferably, the compound comprises a metal oxide, hydroxide or carbonate, and the boron-containing compound is boric acid or diboron trioxide.
Preferably, when the intermediate is pressed into a sheet-like molded body, the intermediate is pressed into a disc at a pressing pressure of 14 to 18Mpa.
Preferably, the reducing atmosphere adopts H with the volume fraction of 5-10 percent 2 And 95-90% N 2 Is a mixed gas of (a) and (b).
Preferably, the concentration of the hydrochloric acid solution is 0.005-0.03 mol/L.
Preferably, when the powder obtained by secondary calcination and grinding is soaked in hydrochloric acid solution to remove impurities, 3-6 g of the powder obtained by secondary calcination and grinding is added to 10-20 mL.
The invention also provides a warm white light LED device, which comprises a near ultraviolet light LED chip and blue, green and red three primary color fluorescent powder arranged on the near ultraviolet light LED chip; wherein, the blue fluorescent powder adopts borate blue luminous fluorescent powder which is suitable for near ultraviolet excitation.
Preferably, the near ultraviolet LED chip adopts a GaN semiconductor chip with the emission wavelength of 395nm, and the red fluorescent powder adopts CaAlSiN 3 :Eu 2+ Green phosphor powder (Sr, ba) 2 SiO 4 :Eu 2+ 。
The invention has the following beneficial effects:
the borate blue luminous fluorescent powder suitable for near ultraviolet excitation has wider excitation spectrum range, stronger absorption in the range of 250-410 nm, and the strongest absorption peak is 350-400 nm, and can be effectively excited by the near ultraviolet; the borate blue luminous fluorescent powder is suitable for being excited by near ultraviolet light, emits blue light with higher intensity under the excitation of the near ultraviolet light, has an emission spectrum range of 390-550 nm and an emission dominant wavelength of 470nm, and is suitable for the near ultraviolet light conversion blue fluorescent powder; the borate blue luminous fluorescent powder excited by near ultraviolet light has excellent thermal stability (the emission intensity at 150 ℃ is up to 89% of the room temperature emission intensity), and is suitable for the actual work of a white light LED device;
in the preparation method, the heat treatment processes of presintering and twice calcining are determined according to the composition of raw materials, the preparation temperature is lower, the energy can be effectively saved, the process is simple and environment-friendly, the purity of a product phase is high, and the industrial production is easy; the invention provides a impurity removal strategy of soaking the powder obtained by secondary calcination and grinding in low-concentration hydrochloric acid, so that the luminous intensity of the final fluorescent powder is obviously improved (the luminous intensity is enhanced by 39% after acid treatment), and the quantum efficiency of the fluorescent powder after acid treatment is obviously enhanced and can reach 90% at most.
The warm white light LED device adopts the blue luminous fluorescent powder, and the blue luminous fluorescent powder can be used for exciting white light in near ultraviolet under the warm white light LED device, so that the warm white light LED device provided by the invention can obtain a series of high-efficiency warm white light under the excitation of near ultraviolet light with different currents.
Drawings
FIG. 1 is an X-ray diffraction chart of the phosphor powder prepared in example 1 of the present invention;
FIG. 2 shows the excitation (. Lambda.) of the phosphor prepared in example 1 of the present invention em =470 nm) and emission (λ ex =370 nm) spectral plot;
FIG. 3 is a graph showing the change of the emission intensity of the phosphor prepared in example 1 according to the excitation wavelength;
FIG. 4 is a graph showing the quantum efficiency of the phosphor prepared in example 1 according to the excitation wavelength;
FIG. 5 is a graph showing the change in emission intensity with temperature (lambda.) of the phosphor prepared in example 1 of the present invention ex ＝370nm)；
FIG. 6 is an electroluminescence spectrum of a white light LED device manufactured in embodiment 1 of the present invention;
FIG. 7 shows the excitation (. Lambda.) of the phosphor prepared in example 2 of the present invention em =470 nm) and emission (λ ex =370 nm) spectral plot;
FIG. 8 shows the excitation (. Lambda.) of the phosphor prepared in example 3 of the present invention em =470 nm) and emission (λ ex =370 nm) spectral plot;
FIG. 9 shows the excitation (. Lambda.) of the phosphor prepared in example 4 of the present invention em =470 nm) and emission (λ ex =370 nm).
Detailed Description
The invention will be described in detail below with reference to examples and figures, which are only illustrative of the invention, to which possible embodiments of the invention are not limited.
The invention relates to borate blue luminous fluorescent powder suitable for near ultraviolet excitation, which has the following chemical formula:
LiNa 2 Sr 8-x B 12 O 24 F 6 Cl:xEu 2+ wherein x is Eu 2+ Substituted Sr 2+ The range of the molar ratio of x is as follows: and 0 < x is less than or equal to 0.03.
The preparation method of the borate blue luminous fluorescent powder suitable for near ultraviolet excitation comprises the following steps:
step (1): accurately weighing the general formula LiNa according to the stoichiometric ratio 2 Sr 8-x B 12 O 24 F 6 Cl:xEu 2+ The compound containing Li, na, sr, B, F, cl, eu elements is used as a raw material, and the raw material is ground and mixed uniformly to obtain a raw material mixture; wherein the compound adopts metal oxide, hydroxide or carbonate, and the boron-containing compound adopts boric acid or diboron trioxide;
step (2): putting the raw material mixture obtained in the step (1) into a corundum crucible, placing the corundum crucible into a box-type furnace, presintering for 2-6 hours at 200-500 ℃, cooling to room temperature, grinding and uniformly mixing to obtain an intermediate;
step (3): grinding the intermediate obtained in the step (2) into powder, pressing the powder into a wafer under a pressing machine, wherein the pressure adopted when pressing the wafer is 14-18 MPa; then placing the obtained wafer in a tube furnace protected by reducing atmosphere, calcining for 4-8 hours at 650-750 ℃, naturally cooling and grinding into powder; calcining again under the same condition, naturally cooling and grinding into powder; wherein the reducing atmosphere adopts H with the volume fraction of 5-10 percent 2 And 95-90% N 2 Is a mixed gas of (a) and (b);
step (4): and (3) weighing 3-6 g of the powder obtained in the step (3), placing the powder into a beaker containing 10-20 mL of low-concentration hydrochloric acid with the concentration of 0.005-0.03 mol/L, soaking the powder for 12-72 h, centrifugally washing the powder, and drying the powder at the temperature of 60-75 ℃ to obtain the borate blue luminescent fluorescent powder suitable for near ultraviolet excitation. Wherein, during centrifugal washing, the size of the centrifuge tube is 50mL. When the soaking solution and the powder are separated, the centrifugal speed is 10000r/min, and the centrifugal time is 8-10 min;
the borate blue luminous fluorescent powder suitable for near ultraviolet excitation is applied to a warm white light LED device, and the warm white light LED device comprises a near ultraviolet LED chip and red, green and blue fluorescent powder layers arranged on the near ultraviolet chip. Wherein, the blue fluorescent powder adopts borate blue luminous fluorescent powder which is suitable for near ultraviolet excitation.
In the above scheme of the invention. The near ultraviolet LED chip adopts a GaN semiconductor chip with the emission wavelength of 395 nm; typically, without limitation, the red phosphor is CaAlSiN 3 :Eu 2+ The green fluorescent powder is (Sr, ba) 2 SiO 4 :Eu 2+ 。
Example 1
The preparation method of the borate blue luminous fluorescent powder suitable for near ultraviolet excitation comprises the following steps:
according to the chemical formula LiNa 2 Sr 7.995 B 12 O 24 F 6 Cl:0.005Eu 2+ The stoichiometric ratio of each element is accurately weighed: 2.5mmol Li 2 CO 3 、5mmol NaCl、5mmol NaHCO 3 、24.975mmol SrCO 3 、15mmol SrF 2 、60mmol H 3 BO 3 、0.0125mmol Eu 2 O 3 . Grinding and mixing the raw materials uniformly, then placing the mixture into a corundum crucible, presintering the corundum crucible in a box-type furnace, heating to 200 ℃, preserving heat for 6 hours, naturally cooling to room temperature, discharging, grinding into powder, and pressing the powder into a wafer under a tabletting machine (the pressure is set to be 16 MPa). After the wafer is put into a corundum crucible with a cover, 10% H is put into 2 -90％ N 2 And (3) heating to 650 ℃ in a high-temperature tube furnace with mixed atmosphere in volume ratio, and calcining for 8 hours. Naturally cooling to room temperature, discharging, fully grinding, tabletting again, calcining under the same calcining condition, cooling, and grinding into powder. Weighing 4g of synthesized powder, placing the powder into a beaker containing 15mL of 0.01mol/L hydrochloric acid, soaking the powder for 48 hours, centrifugally washing the powder, and drying the powder to obtain the blue luminescent fluorescent powder excited by the near ultraviolet light.
FIG. 1 is an X-ray diffraction chart of the above-mentioned phosphor of the present example, and the prepared phosphor observes diffraction peaks of a small amount of impurities, indicating the presence of a certain amount of impurities in the prepared phosphor. After the acid treatment with a low concentration, a significant disappearance of the diffraction peaks of the impurities was observed, in comparison with LiNa 2 Sr 8 B 12 O 24 F 6 The standard card of Cl is well matched, which shows that the treated fluorescent powder has higher phase purity. The acid treatment strategy has a good effect on impurity removal. FIG. 2 shows the excitation (. Lambda.) of the above-mentioned phosphor em =470 nm) and emission (λ ex As can be seen from fig. 2, the excitation spectrum of the phosphor prepared in this example ranges from 250 nm to 400nm, and the strongest absorption peak is 370nm, which can be effectively excited by near uv light. The wavelength range of the emission spectrum is 390-550 nm, and the emission dominant wavelength is 470nm, which indicates that the fluorescent powder is suitable for near ultraviolet excitation to convert blue fluorescent powder. At the same time, a significant increase in the luminous intensity of the phosphor after the acid treatment was observed. FIG. 3 is a graph showing the change of the emission intensity of the fluorescent powder with the excitation wavelength, and the emission intensity of the fluorescent powder obtained after the acid treatment at different excitation wavelengths is greatly improved compared with that before the treatment, wherein the emission intensity of the fluorescent powder after the acid treatment at the excitation wavelength of 370nm is improved by 39% compared with that before the treatment. The acid treatment strategy has good influence on the luminous intensity of the fluorescent powder. FIG. 4 is a graph showing the change of the quantum efficiency of the above-mentioned fluorescent powder with the excitation wavelength, and the quantum efficiency of the fluorescent powder obtained after the acid treatment at different excitation wavelengths is obviously improved compared with that before the treatment, wherein the quantum efficiency of the fluorescent powder after the acid treatment at the excitation wavelength of 370nm is as high as 90%, which shows that the quantum efficiency of the fluorescent powder is well influenced by the acid treatment strategy. FIG. 5 is a graph showing the variation of the emission intensity of the fluorescent powder, wherein the emission intensity is as high as 89% of the emission intensity at room temperature at 150 ℃. This shows that the blue fluorescent powder prepared by the invention has excellent thermal stability and is suitable for practical working application of white light LEDs.
The present embodiment provides a warm white LED device. The warm white light LED device comprises the blue light fluorescent powder provided by the invention, red light and green light commercial fluorescent powder capable of being excited by near ultraviolet light, a packaging substrate and a near ultraviolet LED chip. Wherein the blue phosphor is the blue phosphor of example 1, typically without limitation, and the red phosphor is CaAlSiN 3 :Eu 2+ The green fluorescent powder is (Sr, ba) 2 SiO 4 :Eu 2+ . By hairGaN semiconductor LED chip with wavelength of 395 nm; mixing the three primary colors fluorescent powder uniformly, mixing the mixed powder with packaging materials such as epoxy resin or silica gel, coating the mixed powder on an LED chip, and welding a circuit to obtain the white light LED luminescent device.
Table 1 shows the light efficiency data of the white LED packaged in this embodiment at different currents:
TABLE 1
| Current (mA) | Correlated color temperature (K) | CIE-x | CIE-y | Color rendering index |
| 20 | 3946 | 0.3895 | 0.4015 | 89.8 |
| 40 | 3958 | 0.3887 | 0.4009 | 90.4 |
| 60 | 3973 | 0.3877 | 0.3995 | 90.6 |
| 80 | 3948 | 0.3906 | 0.4058 | 89.6 |
| 100 | 3964 | 0.3888 | 0.4023 | 90.2 |
| 120 | 3972 | 0.3880 | 0.4003 | 90.5 |
As can be seen from table 1, the assembled LED device has stable color output and correlated color temperature at different driving currents, and can maintain a stable color rendering index.
The EL spectrum of the white LED device obtained in example 1 is shown in fig. 6, in which the light emission intensity in the red light region is strong. The light efficiency data for the prepared LEDs under different currents are also given in table 1. The prepared LED device shows high color rendering index and moderate color temperature, and can meet the requirements of people on high-quality LEDs.
Example 2
The preparation method of the borate blue luminous fluorescent powder suitable for near ultraviolet excitation comprises the following steps:
according to the chemical formula LiNa 2 Sr 7.99 B 12 O 24 F 6 Cl:0.01Eu 2+ The chemical stoichiometric ratio of each element is accurately weighed: 2.5mmol Li 2 CO 3 、5mmol NaCl、5mmol NaHCO 3 、24.95mmol SrCO 3 、15mmol SrF 2 、60mmol H 3 BO 3 、0.025mmol Eu 2 O 3 . Grinding and mixing the raw materials uniformly, then placing the mixture into a corundum crucible, presintering the corundum crucible in a box-type furnace, heating to 500 ℃, preserving heat for 2 hours, naturally cooling to room temperature, discharging, grinding into powder, and pressing the powder into a wafer under a tabletting machine (the pressure is set to be 14 MPa). After the wafer is put into a corundum crucible with a cover, the wafer is put into 5%H 2 -95％N 2 And (3) heating to 750 ℃ in a high-temperature tube furnace with mixed atmosphere in volume ratio, and calcining for 4 hours. Naturally cooling to room temperature, discharging, tabletting again, calcining again under the same calcining condition, cooling, and grinding into powder. 3g of synthesized powder is weighed and placed in a beaker containing 18mL of 0.005mol/L hydrochloric acid, after soaking for 72 hours, centrifugal washing is carried out, and after drying, the blue luminescent fluorescent powder excited by the near ultraviolet light is obtained.
As shown in FIG. 7, the fluorescent powder sample of the embodiment has an excitation spectrum wavelength ranging from 250 to 400nm and a strongest absorption peak at 370nm, and can be effectively excited by near ultraviolet light. The emission spectrum wavelength range is 390-550 nm, and the emission dominant wavelength is 470nm, which indicates that the fluorescent powder is suitable for blue fluorescent powder converted by near ultraviolet excitation.
Example 3
The preparation method of the borate blue luminous fluorescent powder suitable for near ultraviolet excitation comprises the following steps:
according to the chemical formula LiNa 2 Sr 7.985 B 12 O 24 F 6 Cl:0.015Eu 2+ The chemical stoichiometric ratio of each element is accurately weighed: 2.5mmol Li 2 CO 3 、5mmol NaCl、5mmol NaHCO 3 、24.925mmol SrCO 3 、15mmol SrF 2 、60mmol H 3 BO 3 、0.0375mmol Eu 2 O 3 . Grinding and mixing the raw materials uniformly, then placing the mixture into a corundum crucible, presintering the corundum crucible in a box-type furnace, heating to 500 ℃, preserving heat for 6 hours, naturally cooling to room temperature, discharging, grinding into powder, and pressing the powder into a wafer under a tabletting machine (the pressure is set to be 16 MPa). After the wafer is put into a corundum crucible with a corundum boat, the wafer is put into10％H 2 -90％N 2 In a high-temperature tube furnace with mixed atmosphere, the temperature is raised to 700 ℃ for calcination, and the heat preservation time is 6h. Naturally cooling to room temperature, discharging, tabletting again, calcining again under the same calcining condition, cooling, and grinding into powder. Weighing 4g of synthesized powder, placing the powder into a beaker containing 15mL of 0.02mol/L hydrochloric acid, soaking the powder for 24 hours, centrifugally washing the powder, and drying the powder to obtain the blue luminescent fluorescent powder excited by the near ultraviolet light.
As shown in FIG. 8, the fluorescent powder sample of the embodiment has an excitation spectrum wavelength ranging from 250 to 400nm and a strongest absorption peak at 370nm, and can be effectively excited by near ultraviolet light. The emission spectrum wavelength range is 390-550 nm, and the emission dominant wavelength is 470nm, which indicates that the fluorescent powder is suitable for blue fluorescent powder converted by near ultraviolet excitation.
Example 4
The preparation method of the borate blue luminous fluorescent powder suitable for near ultraviolet excitation comprises the following steps:
according to the chemical formula LiNa 2 Sr 7.97 B 12 O 24 F 6 Cl:0.03Eu 2+ The chemical stoichiometric ratio of each element is accurately weighed: 2.5mmol Li 2 CO 3 、5mmol NaCl、5mmol NaHCO 3 、24.85mmol SrCO 3 、15mmol SrF 2 、60mmol H 3 BO 3 、0.005mmol Eu 2 O 3 . Grinding and mixing the raw materials uniformly, then placing the mixture into a corundum crucible, presintering the corundum crucible in a box-type furnace, heating to 400 ℃, preserving heat for 4 hours, naturally cooling to room temperature, discharging, grinding into powder, and pressing the powder into a wafer under a tabletting machine (the pressure is set to be 18 MPa). After the wafer is put into a corundum crucible with a corundum boat, the wafer is put into 7%H 2 -93％N 2 In a high-temperature tube furnace with mixed atmosphere, the temperature is raised to 700 ℃ for calcination, and the heat preservation time is 4 hours. Naturally cooling to room temperature, discharging, tabletting again, calcining under the same calcining condition, cooling, and grinding into powder. Weighing 6g of synthesized powder, placing the powder into a beaker containing 20mL of 0.03mol/L hydrochloric acid, soaking the powder for 12 hours, centrifugally washing the powder, and drying the powder to obtain the blue luminescent fluorescent powder excited by the near ultraviolet light.
As shown in fig. 9, the excitation spectrum of the fluorescent powder sample of the embodiment has a wavelength range of 250-400 nm, and the strongest absorption peak is 370nm, which can be effectively excited by near ultraviolet light. The emission spectrum wavelength range is 390-550 nm, and the emission dominant wavelength is 470nm, which indicates that the fluorescent powder is suitable for blue fluorescent powder converted by near ultraviolet excitation.
The above examples are illustrative of the invention and are not intended to be limiting; it is understood that modifications and improvements may be made by those skilled in the art based on the technical solution of the present invention, but the modifications and improvements made do not depart from the essential scope of the embodiments of the present invention, and all fall within the protection scope of the technical solution of the present invention.
Claims (10)
1. The borate blue luminous fluorescent powder suitable for near ultraviolet excitation is characterized by comprising the following chemical formula:
LiNa 2 Sr 8-x B 12 O 24 F 6 Cl:xEu 2+ wherein x is Eu 2+ Substituted Sr 2+ The range of the molar ratio of x is as follows: and 0 < x is less than or equal to 0.03.
2. The method for preparing borate blue luminous fluorescent powder suitable for near ultraviolet excitation as claimed in claim 1, which is characterized by comprising the following steps:
uniformly mixing raw material powder of borate blue luminous fluorescent powder suitable for near ultraviolet excitation to obtain a raw material mixture;
presintering the raw material mixture at 200-500 ℃ for 2-6 hours, cooling to room temperature after presintering, grinding into powder and uniformly mixing to obtain an intermediate;
pressing the intermediate into a sheet-like shaped body;
the sheet-shaped formed body is subjected to primary calcination, natural cooling and grinding are carried out after the primary calcination is finished, the ground powder is subjected to secondary calcination, and natural cooling and grinding are carried out after the secondary calcination is finished; the calcination conditions of the primary calcination and the secondary calcination are the same, the temperature during the calcination is 650-750 ℃, the time is 4-8 h, and the atmosphere is a reducing atmosphere;
and (3) soaking the powder obtained by secondary calcination and grinding in hydrochloric acid solution to remove impurities, and separating, washing and drying after the soaking and the impurity removal are finished to obtain the borate blue luminescent fluorescent powder suitable for near ultraviolet excitation.
3. The method for preparing borate blue luminous fluorescent powder suitable for near ultraviolet excitation as claimed in claim 2, wherein the borate blue luminous fluorescent powder adopts a compound containing Li, na, sr, B, F, cl and Eu elements as raw materials.
4. A method for preparing a borate blue light emitting phosphor suitable for near ultraviolet excitation as claimed in claim 3, wherein the compound comprises metal oxide, hydroxide or carbonate, and the boron-containing compound is boric acid or diboron trioxide.
5. The method for preparing blue borate fluorescent powder suitable for near ultraviolet excitation according to claim 2, wherein the intermediate is pressed into a disc when pressed into a sheet-shaped forming body, and the pressing pressure is 14-18 Mpa.
6. The method for preparing borate blue luminous fluorescent powder suitable for near ultraviolet excitation as claimed in claim 2, wherein the reducing atmosphere adopts H with the volume fraction of 5% -10% 2 And 95-90% N 2 Is a mixed gas of (a) and (b).
7. The method for preparing borate blue luminous fluorescent powder suitable for near ultraviolet excitation as claimed in claim 2, wherein the concentration of the hydrochloric acid solution is 0.005-0.03 mol/L.
8. The method for preparing the borate blue luminous fluorescent powder suitable for near ultraviolet excitation according to claim 7, wherein when the powder obtained by secondary calcination and grinding is soaked in hydrochloric acid solution for impurity removal, 3-6 g of the powder obtained by secondary calcination and grinding is added into 10-20 mL.
9. The warm white light LED device is characterized by comprising a near ultraviolet light LED chip and blue, green and red three primary color fluorescent powder arranged on the near ultraviolet light LED chip; wherein the blue fluorescent powder adopts borate blue luminous fluorescent powder which is suitable for near ultraviolet excitation as claimed in claim 1.
10. The warm white LED device of claim 9, wherein the near uv LED chip is a GaN semiconductor chip with an emission wavelength of 395nm, and the red phosphor is CaAlSiN 3 :Eu 2+ Green phosphor powder (Sr, ba) 2 SiO 4 :Eu 2+ 。
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