CN116064033A - Non-agglomerated nitride red fluorescent powder and preparation method thereof - Google Patents

Abstract

The invention discloses a red fluorescent powder without agglomerated nitride and a preparation method thereof, wherein Eu (NO) ₃ ) ₃ The Si powder and the AlN powder are taken as raw materials, and the precursor is prepared by precipitation, standing, cleaning and drying, and is prepared in N ₂ Sintering at 1300-1500 deg.c for 3-6 hr in atmosphere, cooling, crushing, adding Ca in certain amount into glove box ₃ N ₂ And NH ₄ Cl, fully grinding, uniformly mixing, placing into a multifunctional sintering furnace, and adding into N ₂ Sintering for 2 hours at 1700-1900 ℃ under the pressure of 0.9MPa in the atmosphere, cooling, crushing, repeatedly washing with hot nitric acid solution and deionized water respectively, and drying to obtain the final product. The fluorescent powder prepared by the invention emits red fluorescent powder with the peak wavelength of 650-660 nm, has good particle morphology development, clear and complete crystal face, good dispersibility, adjustable particle size, no agglomeration and higher quantum efficiency than commercial powder on the market.

Description

A kind of agglomerate-free nitride red phosphor and preparation method thereof

technical field

The invention relates to a fluorescent powder and a preparation method thereof, in particular to a non-agglomerated nitride red fluorescent powder and a preparation method thereof.

Background technique

In recent years, the development of solid-state lighting technology has improved people's lives, especially the invention of white LED, which provides a new light source for the lighting industry and drives the rapid development of a large number of related industries. White LED is composed of light-emitting diodes and phosphors that are effectively excited by the diodes, so the performance of phosphors directly affects the lighting effect. The white light LED is composed of gallium nitride LED chips emitting blue light and YAG:Ce ³⁺ yellow phosphor powder. Part of the blue light emitted by the gallium nitride LED chip is absorbed by the phosphor powder, which excites the phosphor powder to emit yellow light, and the remaining blue light and yellow light Combine to get white light. This combination is currently the most commonly used combination of white light LEDs on the market, but the biggest shortcoming of the white light produced by this combination is poor color rendering, which is mainly caused by the too weak luminosity of the phosphor in the red light region. Therefore, the main solution to improve the color rendering index of white LEDs is to add phosphors that can be excited by blue light to emit red light to the phosphors.

Nitride CaAlSiN ₃ :Eu ²⁺ phosphor has attracted the attention of scientists and major phosphor manufacturers due to its high thermal stability, chemical stability, and its ability to be efficiently excited by blue light and emit red wavelengths. Using the traditional one-step solid-phase method is currently the most commonly used method for preparing nitride CaAlSiN ₃ :Eu ²⁺ phosphors on the market, but the prepared phosphor particles are often seriously agglomerated (Guang Li., et al. Opt. Mater., 2015.40 .63., Xing Huifeng, et al. Modern Technology Ceramics. 2016.06-0425-09.1005. etc.), resulting in relatively low luminous intensity and quantum efficiency. The preparation of nitride CaAlSiN ₃ :Eu ²⁺ phosphor requires a high sintering temperature (>1500°C), so it has always been a difficult problem in this field to prepare non-agglomerated phosphor particles and improve the quantum efficiency. An increase of 1% will have a greater impact and significance on the field of white LED lighting.

Therefore, how to prepare CaAlSiN ₃ :Eu ²⁺ phosphors with good particle dispersion, perfect particle surface crystallization and high quantum efficiency is of great significance.

Contents of the invention

The object of the present invention is to provide a CaAlSiN ₃ :Eu ²⁺ fluorescent powder with simple process, low cost, easy industrial production, high quantum efficiency and no agglomeration and a preparation method thereof.

In order to achieve the above object, the present invention adopts following technical scheme:

One aspect of the present invention provides a method for preparing a red fluorescent powder without agglomeration of nitrides, the method comprising the following steps:

S1, weigh and mix Si powder, AlN powder and deionized water according to the stoichiometric ratio to prepare a suspension, and add NH ₄ HCO ₃ precipitant;

S2, slowly add the Eu(NO ₃ ) ₃ aqueous solution to the suspension prepared in S1, after 3-8 hours of static, pour off the supernatant, wash with deionized water several times, and dry at 100-120°C to obtain Precursor;

S3, sintering the precursor obtained in S2 at 1300-1500° C. for 3-6 hours under N ₂ atmosphere, after sintering and cooling, take out and crush, add Ca ₃ N ₂ calculated according to the stoichiometric ratio, grind and mix evenly;

S4, sintering the homogeneously mixed raw materials of S3 in _N2 atmosphere, under the pressure of 0.8-1.0 MPa, at 1700-1900° C. for 1.5-2.5 hours, and then cooling to room temperature to obtain the crude product;

S5, crushing the crude product, then repeatedly washing it several times with hot nitric acid solution and deionized water, and drying at 100-120° C. to obtain the final product.

In some embodiments of the present invention, the molar ratio of AlN powder to Si powder in step S1 of the method is 7:13˜1:1.

In some embodiments of the present invention, the molar ratio of Eu(NO ₃ ) ₃ to NH ₄ HCO ₃ in the method is 1:3˜1:5.

In some embodiments of the present invention, the molar ratio of Eu(NO ₃ ) ₃ to Ca ₃ N ₂ in the method is 1:33˜5:33.

The ratio of Eu(NO ₃ ) ₃ and AlN powder or Si powder in the method of the present invention can be adjusted according to the chemical formula of the target product.

The sintering place in step S3 of the method of the present invention can be a place in the art that can realize the parameters described in the present invention, for example, in a high-temperature tube furnace, adding Ca ₃ N ₂ can also be a conventional method in the art, such as Add in the glove box.

The sintering place in step S4 of the method of the present invention can be a place in the art that can realize the parameters described in the present invention, such as a multifunctional sintering furnace.

In some embodiments of the present invention, the hot nitric acid solution in step S5 is nitric acid with a concentration of 5%-10%, and the temperature is controlled at 50-70°C.

The inventor found that the method described in the present invention undergoes two-step sintering of S3 and S4, and by controlling the temperature and time of each step of sintering, CaAlSiN ₃ :Eu ²⁺ with good particle dispersion, no agglomeration and uniform particle size can be prepared Phosphor.

In some embodiments of the present invention, in the method of the present invention, a certain mass ratio of NH ₄ Cl can also be added simultaneously or successively with Ca ₃ N ₂ in step S3. The inventors found that adding a certain mass ratio of NH ₄ After Cl, the external quantum efficiency can be further improved, and phosphor particles with longer shape can be obtained, and the particle size can be adjusted.

In some embodiments of the present invention, adding a certain mass ratio of NH ₄ Cl refers to adding 1-10 wt% of the total mass of the phosphor obtained according to the stoichiometric ratio.

Another aspect of the present invention provides the non-agglomerated nitride red phosphor prepared by the method of the present invention.

The application of the agglomerate-free nitride red phosphor powder prepared by the method of the invention in the field of white light LED lighting.

Compared with prior art, the beneficial effect of the present invention is:

(1) The CaAlSiN ₃ :Eu ²⁺ phosphor powder obtained in the present invention emits red phosphor powder with a peak wavelength of 650-660nm, has good particle morphology development, good dispersibility, clear and complete crystal planes, no agglomeration, adjustable particle size, quantum Higher efficiency, compared with existing products, the external quantum efficiency is increased by more than 3%, which is of great significance to the field of white LED lighting;

(2) The method of the present invention undergoes two-step sintering of S3 and S4, and by controlling the temperature and time of each step of sintering, CaAlSiN ₃ :Eu ²⁺ fluorescent particles with good particle dispersion, no agglomeration and uniform particle size can be prepared pink.

(3) The preparation method provided by the present invention is simple, low in cost, and easy to industrialized production, so that the color rendering index of the white LED is further improved.

Description of drawings

FIG. 1 is a scanning electron micrograph of phosphor powder obtained according to the method described in Comparative Example 1.

FIG. 2 is a scanning electron micrograph of phosphor powder obtained according to the method described in Example 1. FIG.

FIG. 3 is a spectrum diagram of the phosphor powder obtained according to the method described in Example 1 and a comparison result with the product obtained in Comparative Example 1. FIG.

FIG. 4 is a scanning electron micrograph of phosphor powder obtained according to the method described in Example 2. FIG.

Detailed ways

The following examples facilitate a better understanding of the present invention, but do not limit the present invention. The experimental methods in the following examples are conventional methods unless otherwise specified. The test materials used in the following examples, unless otherwise specified, were purchased from conventional biochemical reagent stores.

Comparative example 1

Use the traditional one-step solid-phase method to prepare comparative samples, and weigh the corresponding raw materials according to the chemical formula Ca _0.98 AlSiN ₃ :0.02Eu ²⁺ respectively. The steps are as follows:

S1, in a glove box filled with nitrogen atmosphere, weigh 48.428 grams of Ca ₃ N ₂ , 41.000 grams of AlN powder, 140.28 grams of Si ₃ N ₄ and 7.038 grams of Eu ₂ O ₃ in a mortar, grind and mix evenly; S2, put the mixture obtained in S1 into a multi-functional sintering furnace, sinter at 1800°C for 2 hours under a pressure of 0.9 MPa in _N2 atmosphere, and then cool to room temperature; S3, crush the crude product, and then use 5% heat to Nitric acid solution and deionized water were repeatedly washed three times, and dried at 120°C for 1 hour to obtain the final product.

FIG. 1 is a scanning electron micrograph of phosphor powder obtained according to the method described in Comparative Example 1. As shown in Figure 1, the dispersibility of the particles is poor, the particles are bonded together, and the agglomeration is serious.

Example 1

Weigh the corresponding raw materials according to the chemical formula Ca _0.98 AlSiN ₃ :0.02Eu ²⁺ , and the steps are as follows:

S1, weighed 8.921 grams of Eu(NO ₃ ) ₃ 6H ₂ O, dissolved in deionized solution to prepare a rare earth salt solution; S2, weighed 28.086 grams of Si powder, 41.000 grams of AlN powder and 160 milliliters of deionized water to prepare a suspension solution, and added 3.56 g of NH ₄ HCO ₃ precipitant; S3, slowly added the rare earth brine solution prepared in S1 to obtain a mixed suspension, after static for 5 hours, poured off the supernatant, and repeated washing with deionized water for 3 The second time, dry at 120°C for 1 hour to obtain the precursor; S4, put the precursor obtained in S3 into a high-temperature tube furnace, and sinter at 1400°C for 4 hours under N ₂ atmosphere. Add 48.428 grams of Ca ₃ N ₂ to the glove box, grind it well, and mix it evenly; S5, put the mixed raw material into a multifunctional sintering furnace, and sinter it at 1800°C for 2h in N ₂ atmosphere under 0.9MPa pressure, and then cool to room temperature; S6, crushing the crude product, washing with 5% hot nitric acid solution and deionized water three times, and drying at 120°C for 1 hour to obtain the final product.

FIG. 2 is a scanning electron micrograph of phosphor powder obtained according to the method described in Example 1. FIG. As can be seen in Figure 2, compared with the results in Figure 1 obtained in Comparative Example 1, the particles in Figure 2 have no agglomeration, better dispersion, and more uniform particle size.

FIG. 3 is a comparison result of the phosphor spectrum obtained by the method described in Example 2 and the phosphor spectrum obtained by the method described in Comparative Example 1. FIG. As shown in FIG. 3 , the excitation spectrum and emission spectrum intensity of the phosphor powder obtained by the method described in Example 1 are higher than those obtained by the method described in Comparative Example 1.

Example 2

Weigh the corresponding raw materials according to the chemical formula Ca _0.98 AlSiN ₃ :0.02Eu ²⁺ , and the steps are as follows:

S1, weighed 8.921 grams of Eu(NO ₃ ) ₃ 6H ₂ O, dissolved in deionized to prepare a rare earth salt solution; S2, weighed 28.086 grams of Si powder, 41.000 grams of AlN powder and 160 milliliters of deionized water to prepare a suspension solution, and added 3.56 g of NH ₄ HCO ₃ precipitant; S3, slowly added the rare earth brine solution prepared in S1 to obtain a mixed suspension, after static for 5 hours, poured off the supernatant, and repeated washing with deionized water for 3 The second time, dry at 120°C for 1 hour to obtain the precursor; S4, put the precursor obtained in S3 into a high-temperature tube furnace, and sinter at 1400°C for 4 hours under N ₂ atmosphere. Add 48.428 grams of Ca ₃ N ₂ and 4.177 grams of NH ₄ Cl in the glove box, fully grind, and mix well; S5, put the well-mixed raw materials into a multifunctional sintering furnace, in N ₂ atmosphere, under 0.9MPa pressure, 1800 Sinter at ℃ for 2 hours, then cool to room temperature; S6, crush the crude product, wash with 5% hot nitric acid solution and deionized water three times, and dry at 120℃ for 1 hour to obtain the final product.

FIG. 4 is a scanning electron micrograph of phosphor powder obtained according to the method described in Example 2. FIG. It can be seen from Figure 4 that when an appropriate amount of NH ₄ Cl is added, the shape of the particles becomes longer compared to Figure 2 .

Example 3

Weigh the corresponding raw materials according to the chemical formula Ca _0.98 Al _0.85 Si _1.15 N ₃ :0.02Eu ²⁺ , the steps are as follows:

S1, weighed 8.921 grams of Eu(NO ₃ ) ₃ 6H ₂ O, dissolved in deionized to prepare a rare earth salt solution; S2, weighed 32.300 grams of Si powder, 34.850 grams of AlN powder and 160 ml of deionized water to prepare a suspension solution, and added 3.56 g of NH ₄ HCO ₃ precipitant; S3, slowly added the rare earth brine solution prepared in S1 to obtain a mixed suspension, after static for 5 hours, poured off the supernatant, and repeated washing with deionized water for 3 The second time, dry at 120°C for 1 hour to obtain the precursor; S4, put the precursor obtained in S3 into a high-temperature tube furnace, and sinter at 1400°C for 4 hours under N ₂ atmosphere. Add 48.428 grams of Ca ₃ N ₂ and 4.181 grams of NH ₄ Cl in the glove box, fully grind, and mix well; S5, put the well-mixed raw materials into a multifunctional sintering furnace, in N ₂ atmosphere, under 0.9MPa pressure, 1800 Sinter at ℃ for 2 hours, then cool to room temperature; S6, crush the crude product, wash with 5% hot nitric acid solution and deionized water three times, and dry at 120℃ for 1 hour to obtain the final product.

Table 1 is the comparison result of the optical performance parameters of the phosphor powder obtained according to Example 3 and Comparative Example 1 and the commercial powder on the market.

【Table 1】

The peak positions of the luminescence curves, CIE color coordinates and external quantum efficiency shown in Table 1 are the results measured by excitation with blue light of 450 nm by a fluorescence spectrometer.

Claims (9)

1. A method for preparing red fluorescent powder without agglomeration of nitrides, characterized in that, the method may further comprise the steps: S1, weigh and mix Si powder, AlN powder and deionized water according to the stoichiometric ratio to prepare a suspension, and add NH ₄ HCO ₃ precipitant; S2, slowly add the Eu(NO ₃ ) ₃ aqueous solution to the suspension prepared in S1, after 3-8 hours of static, pour off the supernatant, wash with deionized water several times, and dry at 100-120°C to obtain Precursor; S3, sintering the precursor obtained in S2 at 1300-1500° C. for 3-6 hours under N ₂ atmosphere, after sintering and cooling, take out and crush, add Ca ₃ N ₂ calculated according to the stoichiometric ratio, grind and mix evenly; S4, sintering the homogeneously mixed raw materials of S3 in _N2 atmosphere, under the pressure of 0.8-1.0 MPa, at 1700-1900° C. for 1.5-2.5 hours, and then cooling to room temperature to obtain the crude product; S5, crushing the crude product, then repeatedly washing it several times with hot nitric acid solution and deionized water, and drying at 100-120° C. to obtain the final product. 2. The method for preparing agglomerate-free nitride red phosphor powder according to claim 1, characterized in that the molar ratio of AlN powder to Si powder in step S1 is 7:13˜1:1. 3 . The method for preparing the agglomeration-free nitride red phosphor according to claim 1 , wherein the molar ratio of Eu(NO ₃ ) ₃ to NH ₄ HCO ₃ is 1:3˜1:5. 4 . The method for preparing agglomeration-free nitride red phosphor according to claim 1 , wherein the molar ratio of Eu(NO ₃ ) ₃ to Ca ₃ N ₂ is 1:33˜5:33. 5 . The method for preparing red phosphor powder without agglomeration of nitrides according to claim 1 , wherein the hot nitric acid solution in step S5 is nitric acid with a concentration of 5% to 10%, and the temperature is controlled at 50 to 70°C. 6 . The method for preparing agglomerate-free nitride red phosphor according to claim 1 , characterized in that, in step S3 , a certain mass ratio of NH ₄ Cl is added simultaneously or successively with Ca ₃ N ₂ . 7. The preparation method of the non-agglomerated nitride red phosphor powder according to claim 6, characterized in that adding a certain mass ratio of NH ₄ Cl refers to 1-10 wt% of the total mass of the phosphor powder obtained according to the stoichiometric ratio join in. 8. The non-agglomerated nitride red phosphor prepared by the method according to any one of claims 1-7. 9. The application of the non-agglomerated nitride red phosphor powder prepared by the method according to any one of claims 1 to 7 in the field of white light LED lighting.

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