CN114316957B - Blue light excited red fluorescent material and preparation method and application thereof - Google Patents
Blue light excited red fluorescent material and preparation method and application thereof Download PDFInfo
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Abstract
The invention provides a blue light excited red fluorescent material, and a preparation method and application thereof, and belongs to the technical field of fluorescent materials. The invention uses CaO and H 2 O、Eu(NO 3 ) 3 As raw materials, a carbonization precipitation method is adopted to synthesize a precursor CaCO 3 :Eu 3+ Then calcined by a carbon powder reduction method and then N is added 2 Preparing CaO Eu by secondary calcination 2+,3+ And (4) red fluorescent powder. The invention utilizes Eu 3+ First occupying CaCO 3 Ca in (1) 2+ Can generate calcium vacancies due to charge imbalance, thereby making Eu the most useful 3+ Is easier to be reduced into Eu 2+ Make Eu to be 2+ The luminescence of the fluorescent material is enhanced, and the red fluorescence emission excited by blue light is realized. The obtained fluorescent material can be excited by blue light to obtain a red light wide emission band with the center positioned at 650-670 nm. Further, the invention dopes Cl ‑ The fluorescent material can have a red wide emission band and a blue wide emission band under near ultraviolet excitation.
Description
Technical Field
The invention relates to the technical field of fluorescent materials, in particular to a blue light excited red fluorescent material and a preparation method and application thereof.
Background
At present, the main realization of white light LED is that blue light chip excites yellow fluorescent powder (such as YAG: ce) 3+ ) However, since it lacks a red light component, it has disadvantages such as a low color rendering index and a high color temperature. If the red fluorescent powder can be introduced, the color rendering index and the color temperature of the white light LED can be effectively improved.
In recent years, eu has been adjusted 2+ The research on doped sulfide and nitride-based red fluorescent powder is more, but the sulfide fluorescent powder is sensitive to water and is easy to generate H 2 S, is not favorable for its lifeAnd can also damage the device; the preparation conditions of the nitride fluorescent powder are harsh, and the price is high, so that the application of the nitride fluorescent powder in a white light LED is limited.
Compared with sulfide and nitride, the oxide-based fluorescent powder has the advantages of low cost, simple preparation process, environmental friendliness and the like. But due to Eu 2+ And O 2- The covalent interaction between the Eu and the Eu is weak, and the Eu under blue light excitation is difficult to realize in oxide-based fluorescent powder 2+ And red emission.
Disclosure of Invention
In view of this, the present invention aims to provide a blue light excited red fluorescent material, and a preparation method and an application thereof.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of a blue light excited red fluorescent material, wherein the chemical formula of the blue light excited red fluorescent material is CaO: xEu 2+,3+ ,yCl - Wherein x is more than or equal to 0.001 and less than or equal to 0.05,0 and less than or equal to 0.5, and the valence of Eu is +2 and +3, the preparation method comprises the following steps:
(1) Mixing CaO with boiling water, aging to obtain Ca (OH) 2 Slurry;
mixing the Ca (OH) 2 Slurry with Eu (NO) 3 ) 3 Mixing, introducing CO 2 Gas is used for precipitation reaction to obtain Eu doped 3+ CaCO of 3 ；
(2) When y =0, doping the Eu with 3+ CaCO of 3 Placing in carbon powder environment, performing first calcination without contact with carbon powder, wherein incomplete combustion of carbon powder in the first calcination process generates reducing agent CO, and reducing Eu 3+ Obtaining a red fluorescent material precursor excited by blue light;
when y is more than 0 and less than or equal to 0.5, the Eu is doped 3+ CaCO of 3 Mixing with soluble chloride salt to obtain mixture, placing the mixture in carbon powder environment, and performingFirst calcining, in which carbon powder is incompletely combusted to generate reducing agent CO and Eu is reduced 3+ Obtaining a red fluorescent material precursor excited by blue light;
(3) In N 2 And under the atmosphere, carrying out secondary calcination on the red fluorescent material precursor excited by the blue light to obtain the red fluorescent material excited by the blue light.
Preferably, the Ca (OH) 2 Ca (OH) in the slurry 2 The mass percentage of the component (A) is 5-10%.
Preferably, said CO is contained 2 The gas being CO 2 And N 2 The mixed gas of (1), CO in the mixed gas 2 And N 2 The volume ratio is 1:2-3.
Preferably, the temperature of the precipitation reaction is 10 to 15 ℃.
Preferably, the temperature of the first calcination is 1000-1500 ℃, and the heat preservation time is 2-8 h; the atmosphere of the first calcination is air.
Preferably, the temperature of the second calcination is 800-1000 ℃, and the heat preservation time is 1-3 h.
The invention provides the blue light excited red fluorescent material prepared by the preparation method, and the chemical formula of the blue light excited red fluorescent material is CaO: xEu 2+,3+ ,yCl - Wherein x is more than or equal to 0.001 and less than or equal to 0.05,0 and less than or equal to 0.5, and the valence of Eu is +2 and + 3.
Preferably, the particle size of the blue light-excited red fluorescent material is 2 to 10 μm.
Preferably, when y =0, the excitation wavelength of the blue light excited red fluorescent material is 450 to 470nm, and the emission wavelength is 550 to 780nm;
when y is more than 0 and less than or equal to 0.5, the emission wavelength is 400-550 nm and 550-780 nm when the excitation wavelength of the red fluorescent material excited by the blue light is 300-400 nm;
when the excitation wavelength of the red fluorescent material excited by the blue light is 450-470 nm, the emission wavelength is 550-780 nm.
The invention provides application of the blue light excited red fluorescent material as a white light LED fluorescent material.
The invention provides a blue light excited red fluorescent material, which has a chemical formula of CaO: xEu 2+,3+ ,yCl - Wherein x is more than or equal to 0.001 and less than or equal to 0.05,0 and less than or equal to 0.5, and the Eu has the valence of +2 and + 3. The invention utilizes Eu 3+ First occupying CaCO 3 Ca in (1) 2+ Can generate calcium vacancies due to charge imbalance, thereby causing Eu to be in a state of equilibrium 3+ Is easier to be reduced into Eu 2+ Make Eu to be 2+ The red fluorescence emission excited by blue light is realized. The obtained fluorescent material can be excited by blue light to obtain a red light wide emission band with the center positioned at 650-670 nm. Further, the invention is characterized in that Cl is doped - The fluorescent material can have a red wide emission band and a blue wide emission band under near ultraviolet excitation. The invention provides a preparation method of the blue light excited red fluorescent material, which mixes CaO and boiling water, and ages to obtain Ca (OH) 2 Slurry; mixing the Ca (OH) 2 Slurry with Eu (NO) 3 ) 3 Mixing, introducing CO 2 Gas, carrying out a precipitation reaction during which Eu is present 3+ Para CaCO 3 Doping is carried out; then doped with Eu 3+ CaCO of 3 (or doped with Eu) 3+ CaCO of 3 And soluble chloride salt) in a carbon powder environment, and subjected to a first calcination. The invention takes carbon powder as a reducing agent, on one hand, the carbon powder generates CO in incomplete combustion and can be used for Eu 3+ Carrying out partial reduction, on the other hand, caCO 3 Decomposing to CO in the first calcination 2 ，CO 2 Reacting with carbon powder to generate CO, p-Eu 3+ Partial reduction is carried out to finally obtain Eu-doped 3+ 、Eu 2+ The blue light excited red fluorescent material precursor. Then the invention carries out secondary calcination to lead the residual CaCO in the red fluorescent material precursor excited by the blue light 3 All converted into CaO to obtain the red fluorescent material excited by blue light. The preparation method provided by the invention is simple to operate, the raw materials are easy to obtain, the method is suitable for industrial batch production, the obtained blue light excited red fluorescent material has high emission intensity, and the emission intensity is more than or equal to 300 ten thousand under the excitation of 466 nm. The results of the examples show that it is possible to obtain,the invention provides a red fluorescent material excited by blue light and commercial yellow fluorescent powder YAG Ce 3+ The 460nm blue light chip is assembled into an LED device, the color temperature of light emitted by the LED device in a white light region (x =0.4085, y = 0.3912) is 3435K, the color rendering index is 91.2, the light efficiency is 49.36Im/W, the LED device has the advantages of low color temperature and high color rendering index, and the problems of low color rendering index and high color temperature caused by the fact that the white light LED lacks a red light component can be well solved.
Drawings
FIG. 1 is an excitation spectrum and an emission spectrum of a red phosphor obtained in example 1 of the present invention.
FIG. 2 shows CaO: xEu 2+,3+ The relation curve diagram of the value of x (x is more than or equal to 0.001 and less than or equal to 0.05) in the red fluorescent powder and the luminous intensity of the fluorescent powder.
FIG. 3 is a comparison graph of the emission spectra of the red phosphor obtained in example 1 of the present invention and the red phosphor obtained by the high temperature solid phase method in the prior art.
FIG. 4 is an excitation spectrum and an emission spectrum of the red phosphor obtained in example 2 of the present invention.
Fig. 5 is a graph of an emission spectrum of an LED device in example 3 of the present invention.
Detailed Description
The invention provides a preparation method of a blue light excited red fluorescent material, wherein the chemical formula of the blue light excited red fluorescent material is CaO: xEu 2+,3+ ,yCl - Wherein x is more than or equal to 0.001 and less than or equal to 0.05,0 and less than or equal to 0.5, and the valence of Eu is +2 and + 3.
In the invention, the CaO is xEu 2+，3+ ,yCl - To be doped with Eu 2+ And Eu 3+ Or is doped with Eu 2+ 、Eu 3+ And Cl - CaO of (2).
In the present invention, x represents a molar ratio of Eu to CaO, 0.001. Ltoreq. X.ltoreq.0.05, preferably, x =0.01.
In the present invention, y represents a molar ratio of Cl to CaO, and 0. Ltoreq. Y.ltoreq.0.5, preferably, 0.1. Ltoreq. Y.ltoreq.0.3.
In the present invention, the preparation method comprises the steps of:
(1) Mixing CaO with boiling water, aging to obtain Ca (OH) 2 Slurry;
mixing the Ca (OH) 2 Slurry with Eu (NO) 3 ) 3 Mixing, introducing CO 2 Gas, performing precipitation reaction to obtain Eu-doped Eu 3+ CaCO of 3 ；
(2) When y =0, doping the Eu with 3+ CaCO of 3 Placing in carbon powder environment, performing first calcination without contact with carbon powder, wherein incomplete combustion of carbon powder in the first calcination process generates reducing agent CO, and reducing Eu 3+ Obtaining a red fluorescent material precursor excited by blue light;
when y is more than 0 and less than or equal to 0.5, the Eu is doped 3+ CaCO of 3 Mixing with soluble chlorine salt to obtain a mixture, placing the mixture in a carbon powder environment, and performing first calcination without contacting with carbon powder, wherein the carbon powder is incompletely combusted in the first calcination process to generate a reducing agent CO and reduce Eu 3+ Obtaining a red fluorescent material precursor excited by blue light;
(3) In N 2 And under the atmosphere, carrying out secondary calcination on the red fluorescent material precursor excited by the blue light to obtain the red fluorescent material excited by the blue light.
The invention mixes CaO with boiling water, and ages to obtain Ca (OH) 2 And (3) slurry. In the present invention, the mixing is preferably performed in the following manner: pouring boiling water into a container containing CaO.
In the present invention, the aging time is preferably 12 to 24 hours, more preferably 18 to 20 hours.
The invention uses the Ca (OH) 2 Slurry with Eu (NO) 3 ) 3 Mixing, introducing CO 2 Gas, performing precipitation reaction to obtain Eu-doped Eu 3+ CaCO of 3 。
In the present invention, the Eu (NO) 3 ) 3 Preferably Eu (NO) 3 ) 3 Solution of said Eu (NO) 3 ) 3 The concentration of the solution is preferably 0.5 to 1mol/L. For said Eu (NO) of the present invention 3 ) 3 The source of (A) is not particularly limited, and those conventionally commercially available in the art are usedEu(NO 3 ) 3 Or prepared by itself. When Eu (NO) is prepared by itself 3 ) 3 Preferably, the preparation method comprises the following steps:
eu is added 2 O 3 Heating and mixing with concentrated nitric acid to obtain Eu (NO) 3 ) 3 。
In the present invention, the heating and mixing are preferably performed under stirring. In the present invention, the temperature of the heating is preferably 80 ℃.
In the present invention, the molar amount of Eu in the soluble europium salt is preferably Ca (OH) 2 The molar amount of Ca in the slurry is 0.1 to 5%, more preferably 0.5 to 2%. In the present invention, the mixing is preferably performed by stirring, and the stirring time is preferably 0.5h.
In the present invention, the CO-containing component 2 The gas is preferably CO 2 And N 2 The mixed gas of (1), CO in the mixed gas 2 And N 2 The volume ratio is preferably 1:2 to 3, more preferably 1.
In the present invention, the precipitation reaction is preferably carried out in an ice-water bath. In the present invention, the temperature of the precipitation reaction is preferably 10 to 15 ℃, more preferably 12 to 14 ℃.
In the present invention, when the pH of the obtained precipitation reaction liquid is 7, the precipitation reaction is terminated and the precipitation reaction is stopped.
After the precipitation reaction is finished, the invention preferably performs post-treatment on the obtained precipitation reaction liquid, and the post-treatment preferably comprises:
carrying out solid-liquid separation on the precipitation reaction liquid, washing and drying the obtained solid to obtain Eu doped 3+ CaCO of 3 And (3) a solid.
In the present invention, the solid-liquid separation is preferably performed by filtration; the washing is preferably distilled water washing; in the present invention, the temperature of the drying is preferably 80 to 120 ℃, more preferably 100 ℃; the time is preferably 24 to 48 hours, more preferably 30 to 36 hours.
In the present invention, when y =0, the Eu-doped is 3+ CaCO of 3 In a carbon powder environment, withThe carbon powder is not contacted with the Eu, the first calcination is carried out, the carbon powder is not completely combusted in the first calcination process to generate a reducing agent CO, and the Eu is reduced 3+ And obtaining the red fluorescent material precursor excited by the blue light.
In the present invention, the Eu is doped 3+ CaCO of 3 The mode of placing the carbon powder in the carbon powder-containing environment without contacting with the carbon powder is preferably as follows:
will be doped with Eu 3+ CaCO of 3 Placing in a small crucible, and covering until the crucible is not completely covered; then Eu will be placed 3+ CaCO of 3 The small crucible is arranged in the large crucible, carbon powder is filled in the gap between the two crucibles, and the small crucible is not completely covered tightly after being covered.
In the present invention, the carbon powder is preferably activated carbon powder. In the present invention, the temperature of the first calcination is preferably 1000 to 1500 ℃, more preferably 1200 to 1400 ℃; the heat preservation time is preferably 2 to 8 hours, and more preferably 4 to 6 hours; the atmosphere for the first calcination is preferably air. In the present invention, the first calcination is preferably carried out in a muffle furnace. The invention takes carbon powder as a reducing agent, on one hand, the carbon powder generates CO in incomplete combustion and can be used for Eu 3+ Carrying out partial reduction, on the other hand, caCO 3 Decomposing to CO in the first calcination 2 ，CO 2 Reacting with carbon powder to generate CO, p-Eu 3+ Performing partial reduction to obtain Eu doped 3+ 、Eu 2+ The blue light excited red fluorescent material precursor.
In the invention, when y is more than 0 and less than or equal to 0.5, the Eu is doped 3+ CaCO of 3 Mixing with soluble chloride to obtain a mixture, placing the mixture in a carbon powder environment, and performing first calcination without contact with carbon powder, wherein the carbon powder is incompletely combusted in the first calcination process to generate a reducing agent CO and reduce Eu 3+ And obtaining the red fluorescent material precursor excited by the blue light.
In the present invention, the soluble chloride salt is preferably NH 4 Cl、CaCl 2 、BaCl 2 And NaCl. In the present invention, the soluble chloride salt is used as a flux and a charge compensation agent. In the present invention, theThe mixing is preferably by milling. In the present invention, the mixing time is preferably 0.5h.
In the invention, the mixture is placed in an environment containing carbon powder, and the mode of not contacting with the carbon powder is preferably as follows:
placing the mixture in a small crucible, and covering the small crucible with a cover, wherein the cover is not completely covered tightly; then, the small crucible with the mixture is placed in a large crucible, and the gap between the two crucibles is filled with carbon powder and covered, and the two crucibles are not completely covered.
In the present invention, the carbon powder is preferably activated carbon powder. In the present invention, the specific method of the first calcination is the same as above, and is not described herein again.
After the red fluorescent material precursor excited by the blue light is obtained, the red fluorescent material precursor excited by the blue light is subjected to secondary calcination to obtain the red fluorescent material excited by the blue light. In the present invention, the temperature of the second calcination is preferably 800 to 1000 ℃, more preferably 900 ℃; the heat preservation time is preferably 1 to 3 hours, and more preferably 2 hours; the atmosphere of the second calcination is N 2 . In the present invention, the second calcination is preferably carried out in a tube furnace. The invention uses the second calcination to calcine the residual CaCO in the red fluorescent material precursor excited by the blue light 3 All converted into CaO.
The invention provides a blue light excited red fluorescent material prepared by the preparation method. In the invention, the chemical formula of the blue light excited red fluorescent material is CaO: xEu 2+,3+ ,yCl - Wherein x is more than or equal to 0.001 and less than or equal to 0.05,0 and less than or equal to 0.5, and the valence of Eu is +2 and + 3.
In the invention, the CaO is xEu 2+，3+ ,yCl - To be doped with Eu 2+ And Eu 3+ Or is doped with Eu 2+ 、Eu 3+ And Cl - CaO of (2).
In the present invention, x represents a molar ratio of Eu to CaO, 0.001. Ltoreq. X.ltoreq.0.05, preferably, x =0.01.
In the present invention, y represents a molar ratio of Cl to CaO, and 0. Ltoreq. Y.ltoreq.0.5, preferably, 0.1. Ltoreq. Y.ltoreq.0.3.
In the present invention, the particle size of the blue-excited red fluorescent material is preferably 2 to 10 μm, and more preferably 4 to 8 μm.
In the invention, when y =0, the excitation wavelength of the blue light excited red fluorescent material is 450-470 nm, and the emission wavelength is 550-780 nm;
when y is more than 0 and less than or equal to 0.5, when the excitation wavelength of the red fluorescent material excited by the blue light is 300-400 nm, the emission wavelength is 400-550 nm and 550-780 nm;
when the excitation wavelength of the red fluorescent material excited by the blue light is 450-470 nm, the emission wavelength is 550-780 nm.
The invention provides application of the blue light excited red fluorescent material as a white light LED fluorescent material.
In the present invention, the application method preferably includes the steps of:
red fluorescent material excited by blue light, YAG: ce 3+ And mixing the LED packaging organic silica gel with a curing agent, coating the mixture on the surface of a blue light chip, and performing thermocuring to obtain the white light LED device.
In the invention, the YAG is Ce 3+ Is yellow phosphor powder with Y as component 3 Al 5 O 12 :Ce 3+ . In the invention, the blue light-excited red fluorescent material and YAG Ce 3+ The mass ratio of (A) is preferably 2 to 4:1, more preferably 3:1.
The invention has no special requirement on the specific types of the LED packaging organic silicon glue and the curing agent, and the LED packaging organic silicon glue and the curing agent which are well known to those skilled in the art can be used. In the invention, the LED packaging organic silica gel is commonly called A glue, and the curing agent is commonly called B glue.
In the invention, the mass ratio of the LED packaging organic silica gel to the curing agent to the blue light-excited red fluorescent material is preferably (4-6): (2-3): 1.
in the present invention, the thermal curing preferably includes primary curing and deep curing. In the present invention, the temperature of the primary curing is preferably 100 ℃, and the time is preferably 1h; the deep curing temperature is preferably 150 ℃ and the time is preferably 3h.
The blue light excited red fluorescent material provided by the present invention, the preparation method and the application thereof are described in detail with reference to the following examples, but they should not be construed as limiting the scope of the present invention.
Example 1
(1) 1mol/L Eu (NO) is prepared 3 ) 3 Solution(s)
0.05mol (17.59631 g) of Eu are weighed 2 O 3 Adding appropriate amount of concentrated HNO into a small beaker of 100ml 3 Placing the solution on a heating magnetic stirrer, heating at 80 ℃, stirring until the pH value of the solution is 3-4, cooling, and fixing the volume in a 100ml volumetric flask.
(2) Preparation of Ca (OH) 2 Slurry liquid
Weighing 0.05mol (2.804 g) of CaO in a 150ml conical flask, weighing 40ml of water in a 100ml small beaker, placing the beaker on a heating magnetic stirrer, heating to boil, quickly pouring the mixture into the conical flask containing the CaO while the mixture is boiling, plugging a cover, slightly shaking, sealing the conical flask by using a preservative film after the reaction is completed, and standing and aging for more than 10 hours.
(3) Preparation of CaO 0.01Eu 2+,3+
Measuring 1mL Eu (NO) 3 ) 3 The solution is added to Ca (OH) 2 The slurry was stirred for 0.5h. Transferring Ca (OH) 2 The slurry was transferred to a glass column which was placed in an ice water bath maintaining the reaction temperature at 15 ℃. Introducing CO 2 And N 2 The end point of the reaction was reached when the gas mixture (flow ratio 1:2) had a solution pH = 7. Finally filtering and collecting precipitate, washing with distilled water for three times, drying in an oven at 80 ℃ for 48h, and grinding to obtain CaCO 3 :0.01Eu 3+ And (3) fluorescent powder.
0.5g of CaCO prepared as described above was weighed 3 :0.01Eu 3+ The powder was placed in a smaller 5mL corundum crucible, capped, and then placed in another larger 30mL ceramic crucible, capped. The gap between the two crucibles is filled with activated carbon powder. The large crucible was placed in a muffle furnace and calcined at 1000 ℃ for 2h under atmospheric atmosphere. Cooling to room temperature, taking out the sampleGrinding into powder. Then in a tube furnace in N 2 Calcining at 800 deg.C for 2 hr under atmosphere to remove trace CaCO 3 Impurities. Cooling to room temperature, taking out the sample, and grinding to obtain pink CaO of 0.01Eu 2+,3+ And (3) powder.
FIG. 1 shows CaO in 0.01Eu as the ratio in example 1 of the present invention 2+,3+ Excitation and emission spectra. As can be seen from FIG. 1, the red phosphor prepared by the invention can be excited by blue light (450-470 nm), and obtains a red light wide emission band (550-780 nm) with the center positioned at 650-670 nm, and the emission intensity is high and stable.
Changing Eu (NO) 3 ) 3 The CaO and xEu under different values of x are obtained 2+,3+ 。
FIG. 2 shows CaO xEu 2+,3+ The relation curve diagram of the value of x (x is more than or equal to 0.001 and less than or equal to 0.05) in the red fluorescent powder and the luminous intensity of the fluorescent powder shows that when x is more than 0.01, obvious concentration quenching occurs, caO is Eu 2+,3+ The optimal Eu doping concentration of the red fluorescent powder is 0.01.
Comparative example 1
With CaCO 3 And Eu 2 O 3 Adopts high-temperature solid-phase reaction to synthesize CaO of 0.01Eu 2+,3+ The method comprises the following steps:
mixing CaCO 3 Powder and Eu 2 O 3 The powders were weighed according to the stoichiometric ratio, ground in an agate mortar for 0.5h, placed in a smaller 5mL corundum crucible, covered, then placed in another larger 30mL ceramic crucible, covered. The gap between the two crucibles is filled with activated carbon powder. The large crucible was placed in a muffle furnace and calcined at 1000 ℃ for 2h under atmospheric atmosphere. After cooling to room temperature, the sample was taken out and ground into a powder. Then in a tube furnace in N 2 Calcining at 800 ℃ for 2h under the atmosphere. Cooling to room temperature, taking out the sample, and grinding to obtain pink CaO of 0.01Eu 2+,3+ Powder, noted as S2.
With CaO and Eu 2 O 3 Adopts high-temperature solid-phase reaction to synthesize CaO of 0.01Eu 2+,3+ The method comprises the following steps:
CaO powder and Eu 2 O 3 Powder ofWeighed according to the stoichiometric ratio, ground in an agate mortar for 0.5h, placed in a small corundum crucible with a cover, covered, placed in another large ceramic crucible with a volume of 30mL, and covered. The gap between the two crucibles is filled with activated carbon powder. The large crucible was placed in a muffle furnace and calcined at 1000 ℃ for 2h under atmospheric atmosphere. After cooling to room temperature, the sample was taken out and ground into a powder. Then in a tube furnace in N 2 Calcining at 800 ℃ for 2h under the atmosphere. Cooling to room temperature, taking out the sample, and grinding to obtain pink CaO of 0.01Eu 2+,3+ Powder, noted as S3.
FIG. 3 is a graph showing a comparison of the emission spectra of the red phosphor obtained in example 1 of the present invention and the red phosphor obtained in comparative example 1 by the high temperature solid phase method, in which curve S1 represents CaO:0.01Eu in example 1 2+,3+ . Fig. 3 shows that the red phosphor prepared in example 1 of the present invention has higher emission intensity than the red phosphor prepared by the high temperature solid phase method in the prior art.
Example 2
Preparation of CaO 0.01Eu 2+,3+ ,0.1Cl -
0.5g of CaCO prepared in example 1 was weighed 3 :0.01Eu 3+ Powder, 0.0005mol of NH is added 4 Cl is used as a fluxing agent and a charge compensation agent, is uniformly mixed, is ground for 0.5h, is placed in a small corundum crucible with 5mL, is covered, is placed in another large ceramic crucible with 30mL, and is covered. The gap between the two crucibles is filled with activated carbon powder. The large crucible was placed in a muffle furnace and calcined at 1000 ℃ for 2h under atmospheric atmosphere. After cooling to room temperature, the sample was taken out and ground into a powder. Then in a tube furnace in N 2 Calcining at 800 deg.C for 2h under atmosphere to remove trace CaCO 3 Impurities. Cooling to room temperature, taking out the sample, and grinding to obtain pink CaO of 0.01Eu 2+,3+ ,0.1Cl - And (3) powder.
FIG. 4 shows CaO in 0.01Eu as a proportion in example 2 of the present invention 2+,3+ ,0.1Cl - Excitation and emission spectra. As can be seen from FIG. 4, the present invention is achieved by introducing Cl - So that the fluorescent material has both a red wide emission band (550-780 nm) and a blue wide emission bandEmission band (400-550 nm).
Example 3
0.01Eu as CaO of the red fluorescent powder prepared by the invention 2+,3+ YAG of commercial yellow phosphor powder Ce 3+ Uniformly mixing 2:1 and A, B glue (A glue is organic silica gel, B glue is a curing agent, A: B = 2:1) according to a certain mass ratio, coating the mixture on a 460nm blue chip, primarily baking the chip in a 100 ℃ baking oven for 1h, and then baking the chip for 3h at 150 ℃ until the chip is completely cured, and carrying out next device test after the LED device is packaged.
Fig. 5 is a graph of an emission spectrum of an LED device in example 3 of the present invention, and a driving current of a chip is 20mA. In the emission spectrum, the 460nm peak is contributed by a 460nm blue chip, and the peak in the range of 500-600 nm is YAG: ce 3+ The peak at 600-780 nm is formed by 0.01 Eu: caO 2+,3+ The contribution is made. The LED device emits light in a white light region (x =0.4085, y = 0.3912), the color temperature is 3435K, the luminous efficiency is 49.36Im/W, and the color rendering index is 91.2.
While only commercial yellow phosphor YAG: ce is currently used 3+ LED devices as fluorescent materials combined with blue light chips with low color rendering index (R) a <80 Higher color temperature (CCT)>6000K) And the requirement of the current high-quality LED illumination cannot be met.
As can be shown from the above tests, the CaO to Eu prepared by the invention 2+,3+ The red fluorescent powder can be effectively excited by blue light to realize red light emission, and the technical problem of the existing white light LED can be effectively solved.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (9)
1. The preparation method of the blue light excited red fluorescent material is characterized in that the chemical formula of the blue light excited red fluorescent material is CaO: xEu 2+,3+ ,yCl - Wherein x is more than or equal to 0.001 and less than or equal to 0.05,0 and less than or equal to 0.5, the Eu has a valence of +2 and+3 valency, the preparation process comprising the steps of:
(1) Mixing CaO with boiling water, aging to obtain Ca (OH) 2 Slurry;
mixing the Ca (OH) 2 Slurry with Eu (NO) 3 ) 3 Mixing, introducing CO 2 Gas, performing precipitation reaction to obtain Eu-doped Eu 3+ CaCO of 3 ；
(2) When y =0, doping the Eu with 3+ CaCO (C) 3 Placing in carbon powder environment, performing first calcination without contact with carbon powder, wherein incomplete combustion of carbon powder in the first calcination process generates reducing agent CO, and reducing Eu 3+ Obtaining a red fluorescent material precursor excited by blue light;
when y is more than 0 and less than or equal to 0.5, the Eu is doped 3+ CaCO of 3 Mixing with soluble chloride to obtain a mixture, placing the mixture in a carbon powder environment, and performing first calcination without contact with carbon powder, wherein the carbon powder is incompletely combusted in the first calcination process to generate a reducing agent CO and reduce Eu 3+ Obtaining a red fluorescent material precursor excited by blue light;
(3) In N 2 And carrying out secondary calcination on the red fluorescent material precursor excited by the blue light under the atmosphere to obtain the red fluorescent material excited by the blue light.
2. The method according to claim 1, wherein the Ca (OH) 2 Ca (OH) in the slurry 2 The mass percentage of the component (A) is 5-10%.
3. The method of claim 1, wherein the CO is present 2 The gas being CO 2 And N 2 The mixed gas of (1), CO in the mixed gas 2 And N 2 The volume ratio is 1:2-3.
4. The method according to claim 1, 2 or 3, wherein the temperature of the precipitation reaction is 10 to 15 ℃.
5. The preparation method according to claim 1, characterized in that the temperature of the first calcination is 1000-1500 ℃, and the holding time is 2-8 h; the atmosphere of the first calcination is air.
6. The preparation method according to claim 1, characterized in that the temperature of the second calcination is 800-1000 ℃ and the holding time is 1-3 h.
7. The blue light-excited red fluorescent material prepared by the preparation method of any one of claims 1 to 6, wherein the chemical formula of the blue light-excited red fluorescent material is CaO: xEu 2+,3+ ,yCl - Wherein x is more than or equal to 0.001 and less than or equal to 0.05,0 and less than or equal to 0.5, and the valence of Eu is +2 and + 3;
the particle size of the red fluorescent material excited by the blue light is 2-10 mu m.
8. The blue-excited red fluorescent material according to claim 7, wherein when y =0, the excitation wavelength of the blue-excited red fluorescent material is 450 to 470nm, and the emission wavelength is 550 to 780nm;
when y is more than 0 and less than or equal to 0.5, the emission wavelength is 400-550 nm and 550-780 nm when the excitation wavelength of the red fluorescent material excited by the blue light is 300-400 nm;
when the excitation wavelength of the red fluorescent material excited by the blue light is 450-470 nm, the emission wavelength is 550-780 nm.
9. Use of the blue-excited red fluorescent material according to any one of claims 7 to 8 as a white LED fluorescent material.
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