Preparation method of Mn < 4 + >-doped magnesium aluminum salt red luminescent material containing Lewis acid sites

Abstract

The invention belongs to the technical field of inorganic luminescent materials, and particularly relates to a preparation method of a Mn < 4 + >-doped magnesium aluminum salt red luminescent material containing Lewis acid sites. The method comprises the following steps: preparing a precursor solution according to a chemical formula MgAl (2-x) MnxO4, and carrying out a co-precipitation reaction to generate a precipitate; sequentially carrying out preheating and high-temperature calcination to form a matrix; then activating through Na < + > exchange and H < + > exchange, directionally introducing oxygen vacancies and exposing Al3 < + > octahedral sites, and cooperatively regulating 2E-4A2 red light transition of Mn < 4 + >. The obtained material has excellent thermal stability, is suitable for blue light excited warm white light LED with high color rendering index and low color temperature, and solves the technical defects of insufficient oxygen vacancy and uncontrollable coordination environment of the traditional red light material. The ion exchange method disclosed by the invention solves the problem that the luminescence application is limited due to the fact that Mn < 2 + > is doped through a high-temperature solid-phase method in the prior art, the oxygen vacancy concentration is low, Lewis acid sites are insufficient, and the local coordination environment of Mn < 4 + > cannot be accurately regulated and controlled. The preparation method is simple and easy to operate, and the product is stable in luminescence.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic luminescent materials, and specifically relates to a Mn containing Lewis acid sites. 4+ A method for preparing a red luminescent material doped with magnesium aluminum salt. Background Art

[0002] Currently, phosphor-converted white light emitting diodes (pc-WLEDs) are usually composed of a blue LED and a yellow phosphor (such as Y3Al5O 12 :Ce 3+ ), but due to the lack of red light components, the cool white light it emits has the problems of high correlated color temperature (CCT>4500K) and low color rendering index (CRI; Ra<80). In recent decades, commercial red phosphors (3.5MgO·0.5MgF2·GeO2:Mn 4 ) has been widely used in fluorescent lamps. 4+ ) activated fluoride phosphor (typically represented by K2SiF6:Mn 4+ ) has been commercialized in the field of blue LED-excited white light lighting. 4+ Due to its unique properties, it has been widely studied and has become a key luminescent ion fluoride red light material (such as K2SiF6:Mn 4+ ): Despite its high luminous efficiency, its large-scale application is limited by fluorine toxicity, hygroscopicity and harsh synthesis conditions (HF solvent). Rare earth-based red light materials (such as CaAlSiN3:Eu 2+ ): Depends on scarce rare earth elements (Eu 2+ ), the cost is high and the synthesis requires high temperature and high pressure (>2000℃), and the energy consumption and carbon emission problems are prominent.

[0003] Traditional Mn 4+ Doped oxides have low oxygen vacancy concentration, Mn 4+ Problems such as uncontrollable local coordination environment lead to weak red light emission intensity and poor thermal stability (T 50 <150℃). However, in the traditional preparation method, Mn 4+ The doping efficiency of traditional Mn 4+ Doped oxide materials (such as MgAl2O4:Mn 4+ ) Due to the low oxygen vacancy concentration and insufficient Lewis acid sites, the luminescence application is limited. The existing technology uses high temperature solid phase method to dope Mn 4+ However, oxygen vacancies are easily compensated by impurities, and it is impossible to precisely control the Mn 4+ local coordination environment. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a Mn4+-doped magnesium aluminum salt red luminescent material containing Lewis acid sites, using Na + / H + Exchange with Mn 4+ The doping is combined with placing the mixture in a sintering container and calcining at high temperature to obtain the corresponding magnesium aluminate containing Lewis acid sites. The product can be obtained by simple mixing or grinding and then sintering at high temperature. The preparation method is simple and easy to operate.

[0005] The technical solutions of the present invention are as follows:

[0006] One of the technical solutions of the present invention is to provide a Mn containing Lewis acid sites. 4+ A method for preparing a red luminescent material doped with magnesium aluminum salt comprises:

[0007] Preparation of precursor solution: According to the chemical formula MgAl 2-x Mn x MgCl2·6H3O, Al(NO3)3·9H2O and Mn(NO3)2 were weighed in the stoichiometric ratio of O4 and dissolved in deionized water to form a uniform mixed solution of metal ions;

[0008] Coprecipitation reaction: The precursor solution is slowly added dropwise to ammonia water to generate a white precipitate;

[0009] Heat treatment: After centrifugation, the white precipitate is preheated and calcined at high temperature to obtain Mn 4+ Doped magnesium aluminate matrix MgAl 2-x Mn x O4( Figure 1 );

[0010] Na + Ion exchange: Mn 4+ Doped magnesium aluminate matrix MgAl 2-x Mn x O4 is immersed in NaNO3 solution to obtain Na + -MgAl2O4:Mn 4+ Intermediates ( Figure 2 );

[0011] H + Ion exchange and activation: Na + -MgAl2O4:Mn 4+ The intermediate was immersed in HNO3 solution, and finally H with oxygen vacancies and Lewis acid sites was obtained. + -MgAl2O4:Mn 4+ Red luminescent material.

[0012] As a further option of this preparation method, in the preparation of the precursor solution, Mn 2+ The doping amount x is 0.002-0.006.

[0013] As a further option of this preparation method, in the coprecipitation reaction, the precursor solution is slowly added dropwise to ammonia water, the pH of the system is adjusted to 9.5-10.5, and the reaction is continuously stirred at 70-80°C for 1-2 hours to generate a white precipitate.

[0014] As a further option of the preparation method, in the heat treatment, the preheating treatment is to keep the temperature at 400-600° C. for 3-5 hours;

[0015] The high-temperature calcination is calcination in an inert atmosphere at 700-1200° C. for 2-12 hours.

[0016] As a further option of the preparation method, the inert atmosphere is a nitrogen or argon atmosphere.

[0017] As a further option of this preparation method, in the Na + In ion exchange, Mn 4+ Doped magnesium aluminate matrix MgAl 2-x Mn x O4 is immersed in NaNO3 solution, the pH is adjusted to 9-11, stirred at 80-100℃ for 2-4 hours, centrifuged, washed and dried to obtain Na + -MgAl2O4:Mn 4+ intermediates;

[0018] The concentration of the NaNO3 solution is 2M, and the pH is adjusted using NaOH solution.

[0019] As a further option of this preparation method, in the H + During ion exchange and activation, Na + -MgAl2O4:Mn 4+ The intermediate is immersed in HNO3 solution, treated at 60-80℃ for 1-2 hours, centrifuged and placed in an inert atmosphere, and calcined at 400-600℃ for 2-4 hours to finally obtain H with oxygen vacancies and Lewis acid sites. + -MgAl2O4:Mn 4+ Red luminescent material.

[0020] The second technical solution of the present invention is to provide H with oxygen vacancies and Lewis acid sites. + -MgAl2O4:Mn 4+ Red luminescent material with oxygen vacancies and Lewis acidic sites + -MgAl2O4:Mn4+ Mn in the lattice of red luminescent materials 4+ Occupy Al 3+ Octahedral sites, and through Na + / H + Oxygen vacancies introduced by ion exchange and exposed Al 3+ Lewis acidic sites coordinately regulate Mn 4+ of 2 E→ 4 A2 transition red emission ( Figure 3-Figure 4 ).

[0021] As a further option of red emitting materials, the H-containing materials having oxygen vacancies and Lewis acidic sites are + -MgAl2O4:Mn 4+ Thermal stability of red luminescent materials T 50 ≥200℃.

[0022] The beneficial effects brought about by the technical solutions provided in the embodiments of the present application include at least the following:

[0023] Beneficial effects:

[0024] This invention proposes a wind power prediction method based on data pattern prediction, which achieves technical breakthroughs through the following innovations:

[0025] After the magnesium aluminate of the present invention is calcined in an N2 atmosphere (400-600°C), the material structure is stable, thereby avoiding the phase change or performance attenuation problems of traditional oxide materials caused by high-temperature treatment.

[0026] Compared with the traditional method which requires high temperature (>1500℃) solid phase reaction, the method used in the present invention uses Na + / H + The exchange completes doping at a lower temperature (80-100°C), reducing energy consumption by about 30%.

[0027] During the experimental process of the present invention, the scheme adopts nitrate solution and ammonia system, which avoids the traditional fluoride materials (such as K2SiF6:Mn 4+ )’s reliance on HF solvent complies with green chemistry requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 XRD comparison of samples before and after treatment;

[0029] Figure 2 This is the infrared comparison image of the sample before and after treatment;

[0030] Figure 3 This is the XPS comparison chart of the sample before and after treatment;

[0031] Figure 4 Comparison of emission spectra of samples before and after treatment. DETAILED DESCRIPTION

[0032] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0033] Example 1

[0034] Mn containing Lewis acid sites 4+ A method for preparing a red luminescent material doped with magnesium aluminum salt comprises:

[0035] Preparation of precursor solution: According to the chemical formula MgAl 2-x Mn x MgCl2·6H2O, Al(NO3)3·9H2O and Mn(NO3)2 were weighed in the stoichiometric ratio of O4 and dissolved in deionized water to form a uniform metal ion mixed solution.

[0036] Co-precipitation reaction: The precursor solution is slowly added dropwise to ammonia water to generate a white precipitate.

[0037] Heat treatment: After centrifugation, the white precipitate is preheated and calcined at high temperature to obtain Mn 4+ Doped magnesium aluminate matrix MgAl 2-x Mn x O4, such as Figure 1 shown.

[0038] Na + Ion exchange: Mn 4+ Doped magnesium aluminate matrix MgAl 2-x Mn x O4 is immersed in NaNO3 solution to obtain Na + -MgAl2O4:Mn 4+ Intermediates, such as Figure 2 shown.

[0039] H + Ion exchange and activation: Na + -MgAl2O4:Mn 4+ The intermediate was immersed in HNO3 solution, and finally H with oxygen vacancies and Lewis acid sites was obtained. + -MgAl2O4:Mn 4+ Red luminescent material.

[0040] Example 2

[0041] This application implements the following Mn 4+ Doped magnesium aluminum salt red luminescent material (MgAl 2-x Mn x O4) preparation method.

[0042] S110: doped with different Mn 4+ Magnesium aluminate prepared with a concentration of (x = 0.002).

[0043] A metal nitrate solution was prepared by dissolving MgCl2·6H2O (10 mmol, (10 mmol, 2.033 g), Al(NO3)3·9H2O (20 mmol, 7.50 g), and Mn(NO3)2 (10x mmol, 5.05 mg, x = 0.002) in 50 ml of deionized water. The metal nitrate solution was then added dropwise to 50 mL of ammonia water (NH4OH, 28%). A white precipitate immediately formed after mixing. The pH value of the resulting suspension was approximately 10. The suspension was stirred in a water bath at 75°C for 1 hour. After the reaction was complete, the suspension was centrifuged. A viscous sample was obtained after centrifugation.

[0044] S210: The above synthesised products are dried at 110℃ for 10-12h, then heated at 450℃ for 3-5h, then thoroughly ground, and finally calcined at 700℃-1100℃ for 3 hours to obtain Mn 4+ Doped magnesium aluminum salt luminescent powder. Test its luminescence properties.

[0045] Example 3

[0046] This application implements the following Mn 4+ Doped magnesium aluminum salt red luminescent material (MgAl 2-x Mn x O4) preparation method.

[0047] S120: doped with different Mn 4+ Magnesium aluminate prepared with a concentration of (x = 0.004).

[0048] A metal nitrate solution was prepared by dissolving MgCl2·6H2O (10 mmol, (10 mmol, 2.033 g), Al(NO3)3·9H2O (20 mmol, 7.50 g), and Mn(NO3)2 (10x mmol, 10.05 mg, x = 0.004) in 50 ml of deionized water. The metal nitrate solution was then added dropwise to 50 mL of ammonia water (NH4OH, 28%). A white precipitate immediately formed after mixing. The pH value of the resulting suspension was approximately 10. The suspension was stirred in a water bath at 75°C for 1 hour. After the reaction was complete, the suspension was centrifuged. A viscous sample was obtained after centrifugation.

[0049] S220: The above synthesis must be dried at 110℃ for 10-12h, then heated at 450℃ for 3-5h, then thoroughly ground, and finally calcined at 700℃-1100℃ for 3 hours to obtain Mn 4+ Doped magnesium aluminum salt luminescent powder. Test its luminescence properties.

[0050] Example 4

[0051] This application implements the following Mn 4+ Doped magnesium aluminum salt red luminescent material (MgAl 2-x Mn x O4) preparation method.

[0052] S130: doped with different Mn 4+ Magnesium aluminate prepared with a concentration of (x=0.006).

[0053] A metal nitrate solution was prepared by dissolving MgCl2·6H2O (10 mmol, (10 mmol, 2.033 g), Al(NO3)3·9H2O (20 mmol, 7.50 g), and Mn(NO3)2 (10x mmol, 15.05 mg, x = 0.006) in 50 ml of deionized water. The metal nitrate solution was then added dropwise to 50 mL of ammonia water (NH4OH, 28%). A white precipitate immediately formed after mixing. The pH value of the resulting suspension was approximately 10. The suspension was stirred in a water bath at 75°C for 1 hour. After the reaction was complete, the suspension was centrifuged. A viscous sample was obtained after centrifugation.

[0054] S230: The above synthesis must be dried at 110℃ for 10-12h, then heated at 450℃ for 3-5h, then thoroughly ground, and finally calcined at 700℃-1100℃ for 3 hours to obtain Mn 4+ Doped magnesium aluminum salt luminescent powder. Test its luminescence properties.

[0055] Example 5

[0056] The following implementation of this application prepares Na with Lewis acid + -MgAl2O4:Mn 4+ Powder method.

[0057] S140: Adjust the solution pH to 9 to prepare Na + -MgAl2O4:Mn 4+ powder.

[0058] The prepared MgAl2O4:Mn 4+ Powder and Na + Exchange preparation process: MgAl2O4:Mn 4+The powder was immersed in NaNO3 solution, and the solution pH was adjusted to 9 with sodium hydroxide, and then heated at 80-100℃ and stirred for 2-4 hours, centrifuged and washed, and dried at 100-120℃ to obtain solid Na + -MgAl2O4:Mn 4+ powder.

[0059] S240: Adjust the solution pH to 10 to prepare Na + -MgAl2O4:Mn 4+ powder.

[0060] The prepared MgAl2O4:Mn 4+ Powder and Na + Exchange preparation process: MgAl2O4:Mn 4+ The powder was immersed in NaNO3 solution, and the solution pH was adjusted to 10 with sodium hydroxide, and then heated at 80-100℃ and stirred for 2-4 hours, centrifuged and washed, and dried at 100-120℃ to obtain solid Na + -MgAl2O4:Mn 4+ powder.

[0061] S340: Adjust the solution pH to 11 to prepare Na + -MgAl2O4:Mn 4+ powder.

[0062] The prepared MgAl2O4:Mn 4+ Powder and Na + Exchange preparation process: MgAl2O4:Mn 4+ The powder was immersed in NaNO3 solution, and the solution pH was adjusted to 11 with sodium hydroxide, and then heated at 80-100℃ and stirred for 2-4 hours, centrifuged and washed, and dried at 100-120℃ to obtain solid Na + -MgAl2O4:Mn 4+ powder.

[0063] Example 6

[0064] H with oxygen vacancies and Lewis acidic sites + -MgAl2O4:Mn 4+ Red light-emitting material, wherein H + -MgAl2O4:Mn 4+ Mn in the lattice of red luminescent materials 4+ Occupy Al 3+ Octahedral sites, and through Na + / H + Oxygen vacancies introduced by ion exchange and exposed Al 3+ Lewis acidic sites coordinately regulate Mn4+ of 2 E→ 4 A2 transition red emission, such as Figure 3 and Figure 4 shown.

[0065] The H having oxygen vacancies and Lewis acidic sites + -MgAl2O4:Mn 4+ Thermal stability of red luminescent materials T 50 ≥200℃.

[0066] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this application are merely illustrative and not restrictive, and it should not be assumed that these advantages, strengths, and effects are required of each embodiment of this application. In addition, the specific details disclosed above are merely illustrative and facilitating understanding, and are not restrictive. The above details do not limit this application to necessarily being implemented using the above specific details.

[0067] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to be applied in the widest sense consistent with the principles and novel features of the present invention.

[0068] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A Mn containing Lewis acid sites 4+ The preparation method of the red luminescent material doped with magnesium aluminum salt is characterized in that: include: Preparation of precursor solution: According to the chemical formula MgAl 2-x Mn x MgCl2·6H2O, Al(NO3)3·9H2O and Mn(NO3)2 were weighed in the stoichiometric ratio of O4 and dissolved in deionized water to form a uniform mixed solution of metal ions; Coprecipitation reaction: The precursor solution is slowly added dropwise to ammonia water to generate a white precipitate; Heat treatment: After centrifugation, the white precipitate is preheated and calcined at high temperature to obtain Mn 4+ Doped magnesium aluminate matrix MgAl 2-x Mn x O4; Na + Ion exchange: Mn 4+ Doped magnesium aluminate matrix MgAl 2-x Mn x O4 is immersed in NaNO3 solution to obtain Na + -MgAl2O4:Mn 4+ intermediates; H + Ion exchange and activation: Na + -MgAl2O4:Mn 4+ The intermediate was immersed in HNO3 solution, and finally H with oxygen vacancies and Lewis acid sites was obtained. + -MgAl2O4:Mn 4+ Red luminescent material.

2. The Mn containing Lewis acid sites according to claim 1 4+ The preparation method of the red luminescent material doped with magnesium aluminum salt is characterized by: In the preparation of the precursor solution, Mn 2+ The doping amount x is 0.002-0.

006.

3. The Mn containing Lewis acid sites according to claim 1 4+ The preparation method of the red luminescent material doped with magnesium aluminum salt is characterized by: In the coprecipitation reaction, the precursor solution is slowly added dropwise to ammonia water, the pH of the system is adjusted to 9.5-10.5, and the reaction is continuously stirred at 70-80° C. for 1-2 hours to generate a white precipitate.

4. The Mn containing Lewis acid sites according to claim 1 4+ The preparation method of the red luminescent material doped with magnesium aluminum salt is characterized by: In the heat treatment, the preheating treatment is to keep the temperature at 400-600° C. for 3-5 hours; The high-temperature calcination is calcination in an inert atmosphere at 700-1200° C. for 2-12 hours.

5. The Mn containing Lewis acid sites according to claim 4 4+ The preparation method of the red luminescent material doped with magnesium aluminum salt is characterized by: The inert atmosphere is nitrogen or argon atmosphere.

6. The Mn containing Lewis acid sites according to claim 1 4+ The preparation method of the red luminescent material doped with magnesium aluminum salt is characterized by: In the Na + In ion exchange, Mn 4+ Doped magnesium aluminate matrix MgAl 2-x Mn x O4 is immersed in NaNO3 solution, the pH is adjusted to 9-11, stirred at 80-100℃ for 2-4 hours, centrifuged, washed and dried to obtain Na + -MgAl2O4:Mn 4+ intermediates; The concentration of the NaNO3 solution is 2M, and the pH is adjusted using NaOH solution.

7. The Mn containing Lewis acid sites according to claim 1 4+ The preparation method of the red luminescent material doped with magnesium aluminum salt is characterized by: In the H + During ion exchange and activation, Na + -MgAl2O4:Mn 4+ The intermediate is immersed in HNO3 solution, treated at 60-80℃ for 1-2 hours, centrifuged and placed in an inert atmosphere, and calcined at 400-600℃ for 2-4 hours to finally obtain H with oxygen vacancies and Lewis acid sites. + -MgAl2O4:Mn 4+ Red luminescent material.

8. A H-type catalyst having oxygen vacancies and Lewis acidic sites prepared according to the method of any one of claims 1 to 7 + -MgAl2O4:Mn 4+ Red luminescent material, characterized by: H with oxygen vacancies and Lewis acidic sites + -MgAl2O4:Mn 4+ Mn in the lattice of red luminescent materials 4+ Occupy Al 35 Octahedral sites, and through Na + / H + Oxygen vacancies introduced by ion exchange and exposed Al 35 Lewis acidic sites coordinately regulate Mn 4+ of 2 E→ 4 A2 transition red light emission.

9. The H-containing compound having oxygen vacancies and Lewis acidic sites according to claim 8 + -MgAl2O4:Mn 4+ Red luminescent material, characterized by: The H having oxygen vacancies and Lewis acidic sites + -MgAl2O4:Mn 4+ Thermal stability of red luminescent materials T 50 ≥200℃.

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