CN109957400B - Mn (manganese)4+Preparation method of ion activated fluoride fluorescent powder - Google Patents

Abstract

The invention provides Mn⁴⁺The preparation method of the ion activated fluoride fluorescent powder does not need to form A₂MF₆The saturated solution greatly reduces the consumption requirement of raw materials, and the preparation process can synthesize a target product at room temperature and is convenient to synthesize. And the addition of the precipitant facilitates the preparation, simplifies the synthesis steps and ensures that the prepared fluorescent powder has better optical performance. The fluoride phosphor can be well excited by ultraviolet light to blue light, particularly blue light, and has strong red light emission with an emission peak in the wavelength range of 600-650 nm. The method has the advantages of simple preparation process, short time consumption, high yield of luminescent quantum of the prepared material, and suitability for industrial large-scale preparation.

Description

Mn (manganese)4+Preparation method of ion activated fluoride fluorescent powder

Technical Field

The invention belongs to the technical field of luminescent materials, and particularly relates to Mn⁴⁺A method for preparing ion activated fluoride fluorescent powder.

Background

In recent decades, White Light-Emitting diodes (WLEDs) have attracted much attention because of their advantages of energy saving, environmental protection, long life, and the like, and have gradually replaced traditional incandescent lamps and fluorescent lamps. Currently, the most common method for preparing WLED on the market is to combine a blue GaN chip with yellow YAG Ce³⁺The yellow phosphor absorbs part of the blue light emitted by the GaN chip and emits yellow light, and the yellow light and the unabsorbed blue light are mixed to form white light. Due to the deficiency of the red component in the emission spectrum of yellow-light phosphors, the WLED prepared by the method is a cold white device, the Correlated Color Temperature (CCT) of which is usually greater than 4500K, and the Color Rendering Index (CRI) of which is lower, usually less than 80, resulting in its being limited by many important applications, such as indoor lighting. In order to make up for the defects, appropriate red fluorescent powder needs to be added into the white light LED device, so that the red light emission of the device is enhanced, the cold white light device is changed into a warm white light device, and the color rendering index of the device is improved.

Mn⁴⁺The ion activated fluoride red phosphor material is an ideal red phosphor material. A number of studies have been carried out on this, the patent WO 2007/100824 disclosing Mn⁴⁺Activated A₂MF₆(A is K, Na, Rb, etc.; M is Ti, Si, Sn, Ge, etc.) red-light phosphor; the preparation method comprises the steps of dissolving the raw materials in high-concentration hydrofluoric acid, and heating and volatilizing the raw materials to be dry, wherein a large amount of toxic hydrogen fluoride gas is volatilized in the preparation process, and the preparation process is difficult to control and is not suitable for industrial production; patent CN 102732249 a discloses a preparation method of mixing a first solution containing a fluoride of tetravalent metal M and a second solution containing an alkali metal a or a compound of a solid form a, and reacting to form a precipitate, thereby obtaining a product.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a_xMF_y:Mn⁴⁺Method for preparing fluoride phosphor without forming A_xMF_yThe saturated solution greatly reduces the consumption requirement of raw materials, the preparation process can synthesize the target product at room temperature, the preparation process is simple, the time consumption is short, the luminous quantum yield of the prepared fluorescent powder is high, and the method is suitable for industrial large-scale preparation.

The invention is realized by the following technical scheme:

a_xMF_y:Mn⁴⁺The preparation method of the fluoride fluorescent powder comprises the following steps:

(1) will contain Mn⁴⁺Dissolving the compound (A) and a compound containing alkali metals A and M, or a simple substance or a compound containing M and a compound containing alkali metal A, or a compound containing alkali metals A and M and a compound containing alkali metal A in a solvent to obtain a mixed solution;

(2) adding a precipitating agent into the mixed solution obtained in the step (1) to obtain a precipitate, and preparing to obtain A_xMF_y:Mn⁴⁺A fluoride phosphor wherein x is [ MF ]_y]The absolute value of the charge of the ions, M is selected from one or a combination of more of Si, Ti, Ge, Sn, Zr, Nb, Ta, Y, Ga and Al, the alkali metal A is selected from one or a combination of more of Li, Na, K, Rb and Cs, and Y is 4, 5, 6 or 7.

According to the invention, the method further comprises the steps of:

(3) centrifuging, washing and drying the precipitate obtained in the step (2) to obtain a solid product A_xMF_y:Mn⁴⁺A fluoride phosphor.

Preferably, y is 4 or 6 and x is [ MF ]_y]The absolute value of the charge of the ion.

Preferably, the M is selected from one or a combination of more of Si, Ti, Ge, Sn, Zr, Nb and Ta, or the M is selected from one or a combination of more of Y, Ga and Al; si and/or Ti are also preferred, or Al is also preferred.

Preferably, the alkali metal a is selected from Na and/or K.

According to the invention, said Mn is contained⁴⁺Is selected from K₂MnF₆，Na₂MnF₆，Li₂MnF₆， Rb₂MnF₆Or Cs₂MnF₆Preferably K₂MnF₆，Na₂MnF₆Also preferred is the above compound in crystalline form.

According to the invention, the compounds containing alkali metals A and M are selected from K₂SiF₆And/or K₂TiF₆(ii) a Said compound containing MThe simple substance of (A) is selected from one or a combination of more of Si, Ti, Ge, Sn, Zr, Nb, Ta, Y, Ga and Al; the M-containing compound is selected from SiO₂，TiO₂，GeO₂，SnO₂，ZrO₂， Nb₂O₅，Ta₂O₅，Y₂O₃，Ga₂O₃，Al₂O₃One or a combination of several of them; the compound containing alkali metal A is selected from LiF, NaF and NaHF₂，KF，KHF₂One or more of RbF and CsF.

According to the invention, in the step (1), the solvent is selected from a hydrofluoric acid solution, preferably, the hydrofluoric acid solution has a mass percentage of 20-50 wt%.

According to the invention, in step (1), the Mn is⁴⁺And M is 0.1 to 30%, preferably 1 to 20%, more preferably 2 to 10%.

According to the invention, in step (1), the Mn is⁴⁺The molar ratio of A to A is 0.1 to 15%, preferably 0.5 to 10%, more preferably 1 to 5%.

According to the invention, in the step (2), the precipitant is selected from one or more of methanol, acetone and absolute ethyl alcohol, and is preferably methanol.

According to the invention, in step (2), the volume ratio of the precipitant to the solvent is (0.20-2):1, preferably (0.20-1):1, and more preferably (0.20-0.5): 1.

According to the invention, in step (2), a precipitant is added at a rate; preferably, the precipitant is added at a rate of 0.02ml/s to 10ml/s, preferably 0.05ml/s to 3ml/s, more preferably 0.1ml/s to 0.5ml/s, and even more preferably 0.1ml/s to 0.3 ml/s. The precipitating agent is added at different rates to obtain A with different grain sizes and shapes_xMF_y:Mn⁴⁺A fluoride phosphor.

According to the present invention, in the step (3), the solid product obtained by centrifugation and washing may be further washed with an organic solvent such as absolute ethanol or acetone, preferably acetone, to remove residual acid solution on the surface, and then dried.

According to the invention, the temperature of the drying is 50 ℃ to 100 ℃, preferably 50 ℃ to 80 ℃.

According to the invention, the reaction can be carried out at from 10 to 40 ℃, for example at room temperature.

Preferably, A is_xMF_y:Mn⁴⁺Is selected from A₂MF₆:Mn⁴⁺，A₃MF₆:Mn⁴⁺Or AMF₄:Mn⁴⁺。

Preferably, A is₂MF₆:Mn⁴⁺Is selected from K₂TiF₆:Mn⁴⁺，K₂SiF₆:Mn⁴⁺，Na₂SiF₆:Mn⁴⁺， Na₂TiF₆:Mn⁴⁺，K₂GeF₆:Mn⁴⁺，Na₂SnF₆:Mn⁴⁺，Cs₂TiF₆:Mn⁴⁺Or Cs₂SiF₆:Mn⁴⁺Further preferably K₂TiF₆:Mn⁴⁺，K₂SiF₆:Mn⁴⁺Or Na₂SiF₆:Mn⁴⁺。

Preferably, A is₃MF₆:Mn⁴⁺Selected from Na₃AlF₆:Mn⁴⁺，K₃AlF₆:Mn⁴⁺，Li₃AlF₆:Mn⁴⁺， Rb₃AlF₆:Mn^{4 +}，Cs₃AlF₆:Mn⁴⁺，K₂NaAlF₆:Mn⁴⁺，K₂LiAlF₆:Mn⁴⁺Further, Na is preferable₃AlF₆:Mn⁴⁺、K₃AlF₆:Mn⁴⁺、K₂NaAlF₆:Mn⁴⁺。

Preferably, said AMF₄:Mn⁴⁺Selected from NaYF₄:Mn⁴⁺Or NaGaF₄:Mn⁴⁺。

Has the advantages that:

the invention provides Mn⁴⁺Activated A capable of being excited by violet and blue light_xMF_y:Mn⁴⁺Fluoride compoundsMethod for preparing phosphor without forming A_xMF_yThe saturated solution greatly reduces the consumption requirement of raw materials, and the preparation process can synthesize a target product at room temperature and is convenient to synthesize. And the addition of the precipitant facilitates the preparation and the operation, thereby simplifying the synthesis steps. The fluoride phosphor can be well excited by ultraviolet light to blue light, particularly blue light, and has strong red light emission with an emission peak in the wavelength range of 600-650 nm. The method has the advantages of simple preparation process, short time consumption, high yield of luminescent quantum of the prepared material, and suitability for industrial large-scale preparation.

Drawings

FIG. 1 shows K in example 2₂NaAlF₆:Mn⁴⁺X-ray powder diffraction pattern of the phosphor.

FIG. 2 shows K in example 2₂NaAlF₆:Mn⁴⁺Scanning electron micrographs of the phosphors.

FIG. 3 shows K in example 2₂NaAlF₆:Mn⁴⁺Excitation and emission spectra of the phosphor.

FIG. 4 shows K in example 3₂TiF₆:Mn⁴⁺X-ray powder diffraction pattern of the phosphor.

FIG. 5 shows K in example 3₂TiF₆:Mn⁴⁺Scanning electron micrographs of the phosphors.

FIG. 6 shows K in example 3₂TiF₆:Mn⁴⁺Excitation and emission spectra of the phosphor.

FIG. 7 shows K in example 4₂SiF₆:Mn⁴⁺Scanning electron micrographs of the phosphors.

FIG. 8 shows K in example 4₂SiF₆:Mn⁴⁺Excitation and emission spectra of the phosphor.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are only for illustrating the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that various changes or modifications can be made by those skilled in the art after reading the disclosure of the present invention, and such equivalents also fall within the scope of the invention.

Instruments and devices:

in the invention, the model of the testing instrument of the X-ray powder diffraction pattern is MiniFlex2, the manufacturer is Rigaku, and the radiation wavelength of the copper target is 0.154187 nm.

In the invention, the model of the test instrument of the scanning electron microscope image is JSM-6700F.

In the present invention, the instrument model for the excitation and emission spectrograms is FLS980 (edinburgh instrument).

Example 1: k₂MnF₆Preparation of

K was prepared according to the method described in Angew. chem-Ger. Edit.65,304-304(1953)₂MnF₆And (4) crystals.

0.45g of KMnO₄And 9g KHF₂Dissolving in 30mL of hydrofluoric acid (49%), stirring for 20 minutes, gradually dropping about 1.2mL of hydrogen peroxide (30 wt.%), gradually generating yellow precipitate in the solution, filtering the solution to obtain precipitate, washing with acetone, and drying at 60 ℃ for 2 hours to obtain K₂MnF₆。

Example 2: k₂NaAlF₆:Mn⁴⁺Preparation of fluoride phosphor

0.00741g of K prepared in example 1 were mixed₂MnF₆、0.8197g NaAlO₂、0.1182g KHF₂Dissolving in 10mL of hydrofluoric acid (49 wt.%) solution, stirring for 5 min to fully dissolve, then dripping 10mL of precipitant methanol at the speed of 0.2mL/s, continuing stirring for 5 min at room temperature after 10mL of methanol is completely dripped, stopping stirring, taking out precipitate, centrifuging, washing with acetone for 2 times, and drying at 60 ℃ in an air atmosphere to obtain a product K₂NaAlF₆:Mn⁴⁺A fluoride phosphor.

FIG. 1 is K₂NaAlF₆:Mn⁴⁺X-ray powder diffraction pattern of the fluoride phosphor, indicating that the synthesized product is tetragonal phase K₂NaAlF₆(ii) a FIG. 2 is K₂NaAlF₆:Mn⁴⁺The scanning electron microscope image of the fluoride fluorescent powder shows that the particle size of the powder is about 1 mu m; FIG. 3 is K₂NaAlF₆:Mn⁴⁺Excitation and emission spectra of the fluoride phosphor. It can be seen that K₂NaAlF₆:Mn⁴⁺The fluoride phosphor has strong absorption in the blue region and strong emission in the red region.

Furthermore, it will be understood by those skilled in the art that by varying K in the starting material₂MnF₆Under the condition of no change of other synthesis conditions, different Mn can be prepared⁴⁺Doping concentration of the sample.

Example 3: k₂TiF₆:Mn⁴⁺Preparation of fluoride phosphor

0.00741g of K prepared in example 1 were mixed₂MnF₆、0.2401g K₂TiF₆Dissolving in 10mL of hydrofluoric acid (49 wt.%) solution, stirring for 5 min to fully dissolve, then dripping 10mL of precipitant methanol at the speed of 0.2mL/s, continuing stirring for 5 min at room temperature after 10mL of methanol is completely dripped, stopping stirring, taking out precipitate, centrifuging, washing with acetone for 2 times, and drying at 60 ℃ in an air atmosphere to obtain a product K₂TiF₆:Mn⁴⁺Fluoride red-light fluorescent powder.

FIG. 4 is K₂TiF₆:Mn⁴⁺X-ray powder diffraction pattern of the fluoride phosphor showed that the synthesized product was hexagonal phase K₂TiF₆(ii) a FIG. 5 is K₂TiF₆:Mn⁴⁺Scanning electron microscope image of the fluoride fluorescent powder, wherein the particle size of the powder is about 10 μm; FIG. 6 is K₂TiF₆:Mn⁴⁺Excitation and emission spectra of the fluoride phosphor. It can be seen that K₂TiF₆:Mn⁴⁺The fluoride phosphor has strong absorption in the blue region and strong emission in the red region.

Furthermore, it will be understood by those skilled in the art that K may be added by varying the addition₂MnF₆Under the condition of no change of other synthesis conditions, different Mn can be prepared⁴⁺Doping concentration of the sample.

Example 4: k₂SiF₆:Mn⁴⁺Preparation of fluoride phosphor

0.00741g of K prepared in example 1 were mixed₂MnF₆、0.0601g SiO₂、0.1562g KHF₂Dissolving in 10mL of hydrofluoric acid (49 wt.%) solution, stirring for 5 min to fully dissolve, then dripping 10mL of precipitant methanol at the speed of 0.2mL/s, continuing stirring for 5 min at room temperature after 10mL of methanol is completely dripped, stopping stirring, taking out precipitate, centrifuging, washing with acetone for 2 times, and drying at 60 ℃ in an air atmosphere to obtain a product K₂SiF₆:Mn⁴⁺Fluoride red-light fluorescent powder.

FIG. 7 is K₂SiF₆:Mn⁴⁺Scanning electron micrographs of fluoride phosphors; FIG. 8 is K₂SiF₆:Mn⁴⁺Excitation and emission spectra of the fluoride phosphor. As can be seen from the figure, K₂SiF₆:Mn⁴⁺The fluoride phosphor has strong absorption in the blue region and strong emission in the red region.

Furthermore, it will be understood by those skilled in the art that K may be added by varying the addition₂MnF₆Under the condition of no change of other synthesis conditions, different Mn can be prepared⁴⁺Doping concentration of the sample.

Example 5: na (Na)₂SiF₆:Mn⁴⁺Preparation of fluoride phosphor

0.00741g of K prepared in example 1 were mixed₂MnF₆、0.0601g SiO₂、0.124g NaHF₂Dissolving in 10mL hydrofluoric acid (49 wt.%) solution, stirring for 5 min to dissolve it completely, dropping 10mL methanol as precipitant at 0.2mL/s rate, stirring at room temperature for 5 min, stopping stirring, taking out precipitate, centrifuging, washing with acetone for 2 times, and oven drying at 60 deg.C in air atmosphere to obtain Na product₂SiF₆:Mn⁴⁺Fluoride red-light fluorescent powder.

Moreover, those skilled in the art will appreciate thatBy changing the addition of Na₂MnF₆Under the condition of no change of other synthesis conditions, different Mn can be prepared⁴⁺Doping concentration of the sample.

Example 6: k₂GeF₆:Mn⁴⁺Preparation of fluoride phosphor

0.00741g of K prepared in example 1 were mixed₂MnF₆、0.0726g Ge、0.1562g KHF₂Dissolving in 10mL hydrofluoric acid (49 wt.%) solution, stirring for 5 min to dissolve it fully, then dropping 10mL precipitant methanol at 0.2mL/s rate, after 10mL methanol is completely dropped, stirring at room temperature for 5 min, stopping stirring, taking out precipitate, centrifuging, washing with acetone for 2 times, drying at 60 deg.C in air to obtain product K₂GeF₆:Mn⁴⁺Fluoride red-light fluorescent powder.

Furthermore, it will be understood by those skilled in the art that K may be added by varying the addition₂MnF₆Under the condition of no change of other synthesis conditions, different Mn can be prepared⁴⁺Doping concentration of the sample.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (18)

1. A_xMF_y:Mn⁴⁺The preparation method of the fluoride fluorescent powder comprises the following steps:

(1) will contain Mn⁴⁺Dissolving the compound (A) and a simple substance or compound containing M and a compound containing alkali metal A, or a compound containing alkali metals A and M and a compound containing alkali metal A in a solvent to obtain a mixed solution;

(2) adding a precipitating agent into the mixed solution obtained in the step (1) to obtain a precipitate A_xMF_y:Mn⁴⁺A fluoride phosphor wherein x is [ MF ]_y]Absolute value of charge of ion, M is selected from Si, Ti, Ge, SnOne or more of Zr, Nb, Ta, Y, Ga and Al, alkali metal A is selected from one or more of Li, Na, K, Rb and Cs, and Y is 4, 5, 6 or 7;

said Mn being contained⁴⁺Is selected from K₂MnF₆，Na₂MnF₆，Li₂MnF₆，Rb₂MnF₆Or Cs₂MnF₆；

The compound containing alkali metals A and M is selected from K₂SiF₆And/or K₂TiF₆；

The simple substance containing M is selected from one or a combination of more of Si, Ti, Ge, Sn, Zr, Nb, Ta, Y, Ga and Al;

the M-containing compound is selected from SiO₂，TiO₂，GeO₂，SnO₂，ZrO₂，Nb₂O₅，Ta₂O₅，Y₂O₃，Ga₂O₃，Al₂O₃One or a combination of several of them;

the compound containing alkali metal A is selected from LiF, NaF and NaHF₂，KF，KHF₂One or more of RbF and CsF.

2. The method according to claim 1, characterized in that the method further comprises the steps of:

(3) centrifuging, washing and drying the precipitate obtained in the step (2) to obtain a solid product A_xMF_y:Mn⁴⁺A fluoride phosphor.

3. The method of claim 1, wherein y is 4 or 6 and x is [ MF ]_y]The absolute value of the charge of the ion.

4. The method according to claim 1, wherein M is selected from one or more of Si, Ti, Ge, Sn, Zr, Nb and Ta, or is selected from one or more of Y, Ga and Al.

5. The method according to claim 4, wherein M is selected from Si and/or Ti or is Al.

6. The process according to claim 1, characterized in that the alkali metal A is selected from Na and/or K.

7. The method according to claim 1, wherein the Mn-containing compound is⁴⁺Is selected from K₂MnF₆Or Na₂MnF₆。

8. The process according to any one of claims 1 to 7, wherein in step (1), the solvent is selected from a hydrofluoric acid solution, the hydrofluoric acid solution being 20 to 50wt% by mass.

9. The method according to any one of claims 1 to 7, wherein in step (1), the Mn is⁴⁺And M is 0.1 to 30% by mole.

10. The method according to any one of claims 1 to 7, wherein in step (1), the Mn is⁴⁺The molar ratio of A to A is 0.1-15%.

11. The method according to any one of claims 1 to 7, wherein in the step (2), the precipitating agent is selected from one or more of methanol, acetone and absolute ethyl alcohol.

12. The method according to any one of claims 1 to 7, wherein in step (2), the volume ratio of the precipitant to the solvent is (0.20-2): 1.

13. The method according to any one of claims 1 to 7, wherein in step (2), the precipitant is added at a rate of 0.02ml/s to 10 ml/s.

14. The method as claimed in claim 2, wherein in the step (3), the solid product obtained by centrifugation and washing is further washed with absolute ethanol or acetone to remove residual acid solution on the surface, and then dried.

15. The method of claim 14, wherein the drying temperature is 50 ℃^oC-100^oC。

16. The method of any one of claims 1 to 7, wherein A is_xMF_y:Mn⁴⁺Is selected from A₂MF₆:Mn^{4 +}，A₃MF₆:Mn⁴⁺Or AMF₄:Mn⁴⁺。

17. The method of claim 16, wherein a is₂MF₆:Mn⁴⁺Is selected from K₂TiF₆:Mn⁴⁺，K₂SiF₆:Mn⁴⁺，Na₂SiF₆:Mn⁴⁺，Na₂TiF₆:Mn⁴⁺，K₂GeF₆:Mn⁴⁺，Na₂SnF₆:Mn⁴⁺，Cs₂TiF₆:Mn⁴⁺Or Cs₂SiF₆:Mn⁴⁺；

A is described₃MF₆:Mn⁴⁺Selected from Na₃AlF₆:Mn⁴⁺，K₃AlF₆:Mn⁴⁺，Li₃AlF₆:Mn⁴⁺，Rb₃AlF₆:Mn⁴⁺，Cs₃AlF₆:Mn^{4 +}，K₂NaAlF₆:Mn⁴⁺Or K₂LiAlF₆:Mn⁴⁺；

The AMF₄:Mn⁴⁺Selected from NaYF₄:Mn⁴⁺Or NaGaF₄:Mn⁴⁺。

18. The method of claim 17, wherein a is₂MF₆:Mn⁴⁺Is selected from K₂TiF₆:Mn⁴⁺，K₂SiF₆:Mn⁴⁺Or Na₂SiF₆:Mn⁴⁺；

A is described₃MF₆:Mn⁴⁺Selected from Na₃AlF₆:Mn⁴⁺、K₃AlF₆:Mn⁴⁺Or K₂NaAlF₆:Mn⁴⁺；

The AMF₄:Mn⁴⁺Selected from NaYF₄:Mn⁴⁺Or NaGaF₄:Mn⁴⁺。

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