TW202227592A - Method for preparing [alpha]-cordierite fluorescent powder body in which a precursor solution including an initial solution and an activator is prepared - Google Patents

Abstract

A method for preparing an [alpha]-cordierite fluorescent powder body, which includes (1) preparing a precursor solution including an initial solution and an activator, wherein the initial solution includes (a) a magnesium source selected from at least one of magnesium alkoxides and magnesium salts, (b) an aluminum source selected from at least one of aluminum alkoxide and aluminum salt, (c) a silicon source selected from silicon alkoxide, and (d) a solvent; the activator is respectively selected from manganese (II)-containing activators, chromium (III)-containing activators, titanium (IV)-containing activators, europium (III)-containing activators or cerium (III)-containing activators; (2) adding hydrochloric acid to the precursor solution and performing a hydrolysis reaction to obtain a transparent sol, the molar ratio of hydrochloric acid to the magnesium source ranges from 0.3 to 0.5; (3) subjecting the transparent sol to polycondensation reaction to obtain a transparent gel; and (4) drying the transparent gel and performing a first annealing treatment at a temperature of 1300 DEG C to obtain the [alpha]-cordierite fluorescent powder body.

Description

Preparation method of α-cordierite fluorescent powder

The invention relates to a preparation method of α-cordierite fluorescent powder, in particular to a method for preparing α-cordierite fluorescent powder, in particular to a sol-gel method and doped with manganese-containing activator, chromium-containing activator and titanium-containing activator respectively A preparation method for preparing α-cordierite (α-Mg ₂ Al ₄ Si ₅ O ₁₈ ) phosphors with green, red or blue light emission characteristics, as well as a europium-containing activator or a cerium-containing activator.

Phosphors are key materials for light-emitting diodes (LEDs) and displays. The mainstream technology of existing commercial white LEDs is composed of GaN-based blue LED chips and cerium (Ce)-doped yttrium aluminum garnet (Y ₃ Al ₅ O1 ₂ : Ce ³⁺ , namely YAG: Ce ³⁺ ) yellow phosphors. However, due to the lack of components of green light and red light, it has the disadvantage of low color rendering, which is not suitable for indoor and medical lighting. In contrast, tri-primary-color phosphors can be used not only in monochromatic light components, but also in white LEDs, and have the advantages of small color shift and better color rendering, so tri-primary-color phosphors have great potential for development.

The powder properties of the phosphor powder will affect its luminescent properties. If there is a segregated heterogeneous phase in the powder, the luminous intensity and stability of the phosphor powder will be reduced. In addition to high homogeneity and single phase, the powder also needs to have fine particle size characteristics, especially when the phosphor powder is nano-sized, these characteristics can effectively increase the packing density and reduce the amount of binder to improve its compactness. and luminous efficiency. When applied to display devices, in order to avoid image persistence, the phosphor powder also needs to have short afterglow characteristics (light decay time less than 10 ms).

The composition of the fluorescent material mainly includes a host lattice and an activator, and different activators have specific electron energy levels, which can be used to adjust the emission wavelength of the host. Among them, one of the key technologies yet to be overcome is to develop host materials with chemical stability, thermal stability and high luminous efficiency.

Cordierite (α-Mg ₂ Al ₄ Si ₅ O ₁₈ ) has three allotropes, including orthorhombic β-cordierite, hexagonal μ-cordierite and hexagonal α-cordierite Bluestone, of which μ-cordierite and β-cordierite are metastable phases, while α-cordierite is a high temperature stable phase, especially α-cordierite has high temperature stability and chemical stability, so it is highly valued. α-cordierite has high resistance, low expansion coefficient, low dielectric constant, thermal shock, thermal and chemical stability, and non-toxic properties, which can be used in catalyst carriers, heat exchange components, heat-resistant coatings, electronic packaging materials, printed circuit boards, etc.

Therefore, if α-cordierite fluorescent powder with homogeneous single phase, nano-particle size, and three primary colors can be developed, it can be applied not only to monochromatic light components, but also to full-color displays and improving the color rendering of white LEDs.

Existing cordierite:Mn ²⁺ phosphors are mainly prepared by solid state method. For example, Inorganic Chemistry, vol.53 (2014), p.11396−11403 discloses the preparation of α-cordierite that emits red light (wave peak 600 nm) by a solid-state method by heating at 1300 °C for 6 hours in a reducing atmosphere: Mn ²⁺ fluorescent powder. Another example is Dyes Pigments, vol.148 (2018), p.9-15 discloses the preparation of α-cordierite that emits red light (wave peak 680nm) by a solid-state method by heating at 1400 °C for 5 hours in an air furnace: Mn ⁴⁺ fluorite Light powder.

The existing cordierite: Cr ³⁺ phosphor powder is also prepared by solid state method. For example, Optical Materials, vol.60 (2016), p.188−195 discloses that a phosphor powder capable of emitting red light (wave peak 670 nm) was prepared by solid-state sintering at 1350 °C for 12 hours. After sintering, a large amount of μ- The red light emission of cordierite, MgAl ₂ O ₄ , α-Al ₂ O ₃ and SiO ₂ segregation phase is attributed to the main body of α-Al ₂ O ₃ or MgAl ₂ O ₄ .

So far, there is no literature or report about α-cordierite: Ti ⁴⁺ phosphors.

Existing cordierite:Eu ³⁺ phosphors are mainly prepared by solid state method. For example, Journal of Luminescence, vol.181 (2017), p.49-55 and Journal of Luminescence, vol.197 (2018), p.164-168 disclose the preparation by solid-state method by heating at 1400 °C for 8-10 hours in an air furnace β-cordierite: Eu ³⁺ phosphor powder which can emit red light (wave peak 614~616 nm). In addition, there are also prepared by sol-gel method, such as European Journal of Solid State and Inorganic Chemistry, vol.35 (1998), p.341-355 discloses metal magnesium, aluminum butoxide, silicon ethoxide and europium nitrate β-cordierite emitting red light (peaks 576 nm and 615 nm) was prepared by sol-gel method at 1300 °C for 10 hours using acetone as the precursor and acetylacetone as the chelating agent: Eu ³⁺ phosphor body. And Journal of Solid State Chemistry, vol.171 (2003), p.375-381 discloses that magnesium nitrate, aluminum nitrate, sodium silicate and europium nitrate are used as precursors, and high concentration of citric acid is used as a chelating agent. The α-cordierite:Eu ³⁺ fluorescent powder which can emit red light (wave peak 615 nm) was prepared by calcining at 1200℃ by the glue method, but the powder showed a large amount of μ-cordierite and MgAl ₂ O ₄ segregation phase at the same time;

In addition, the existing cordierite: Ce ³⁺ phosphors are mainly prepared by solid state method. For example, Optical Materials, vol.181 (2017), p.49–55 prepared α-cordierite: Ce ³⁺ fluorescein that emits blue light (wave peak 430nm) by heating at 1350°C for 4 hours in a reducing atmosphere by a solid-state method powder. And Journal of Materials Science: Materials in Electronics, vol.29 (2018), p.7965-7970 discloses the preparation of β-cordierite capable of emitting blue light (wave peak 439 nm) by heating at 1400 °C for 8 hours in an air furnace by a solid-state method : Ce ³⁺ phosphor powder.

The aforementioned solid-state method relies on long-term high-temperature heat treatment, which is a high-cost process with high energy consumption, and has the disadvantage of easily causing powder coarsening, segregation, and the formation of β-cordierite instead of α-cordierite. The aforementioned phosphor powders are used in thin-layer phosphor screens, and it is difficult to increase the packing density and the luminous performance is still insufficient.

In addition, the aforementioned sol-gel method needs to rely on toxic solvents (such as acetone acetone) or high-concentration citric acid as chelating agents, which is easy to cause the powder to produce segregation phase, coarse and hard agglomeration, and low luminous intensity. There is also the disadvantage of unstable reproducibility of α-cordierite.

Therefore, how to improve the existing preparation method of α-cordierite fluorescent powder to prepare α-cordierite fluorescent powder with homogeneity, fine particle size and three primary color emission characteristics has become the direction of current research.

Therefore, the purpose of the present invention is to provide a preparation method of α-cordierite fluorescent powder, which can form gelation naturally, does not need to add any chelating agent, can reduce segregation phase and increase α-cordierite Crystal stability, and the prepared α-cordierite fluorescent powder has high homogeneity, fine particle size, good crystallinity and three primary color emission characteristics, which can overcome the above shortcomings of the prior art.

Therefore, the preparation method of the α-cordierite fluorescent powder of the present invention includes the following steps: (1) preparing a precursor solution, the precursor solution includes a starting solution and an activator, and the starting solution includes (a) selected from magnesium A magnesium source selected from at least one of alkoxides and magnesium salts, (b) an aluminum source selected from at least one of aluminum alkoxides and aluminum salts, (c) a silicon source selected from silicon alkoxides, and (d) a solvent , the activator is selected from manganese (II) activator, chromium (III) activator, titanium (IV) activator, europium (III) activator or cerium (III) activator; (2 ) adding hydrochloric acid to the precursor solution and carrying out a hydrolysis reaction to obtain a transparent sol, wherein the molar ratio of the hydrochloric acid and the magnesium source ranges from 0.3 to 0.5; (3) making the transparent sol carry out a polycondensation reaction to obtain a transparent gel; and (4) drying the transparent gel and performing a first annealing treatment at a temperature of 1300° C. to obtain α-cordierite fluorescent powder, and experiments on the α-cordierite fluorescent powder The formula is α-Mg ₂ Al ₄ Si ₅ O ₁₈ : xM, M represents Mn ²⁺ , Cr ³⁺ , Ti ⁴⁺ , Eu ³⁺ or Ce ³⁺ , x=[M]/[Mg]=1~20 %.

The effect of the present invention is that: the preparation method of the present invention uses specific magnesium source, aluminum source and silicon source, without adding any chelating agent, the gelation can be formed naturally through the polycondensation reaction, and the tight and uniform distribution of the constituent molecules can be maintained, so Can improve the crystallinity of α-cordierite. Furthermore, hydrochloric acid (the molar ratio of hydrochloric acid and magnesium source is in the range of 0.3 to 0.5) is added as a dissolving aid in a specific amount, so that the dispersibility and homogeneity of the generated sol can be greatly improved, and a transparent sol and gel can be formed. glue, and the obtained α-cordierite has high reproducibility, high stability, no segregation phase and smaller average particle size. In addition, adding a specific type of the activator to carry out the hydrolysis reaction, and performing the first annealing treatment at a temperature of 1300 ° C, α-cordierite fluorescent powders with green, red or blue light emission characteristics can be obtained respectively. .

The content of the present invention will be described in detail below:

In this article, the term "manganese-activated α-cordierite phosphor powder" or "α-cordierite: Mn ²⁺ " refers to α-cordierite prepared by doping with manganese (II)-containing activator fluorescent powder. The term "chromium-activated α-cordierite fluorescent powder" or "α-cordierite: Cr ³⁺ " refers to the α-cordierite fluorescent powder obtained by doping with a chromium (III)-containing activator . The term "titanium-activated α-cordierite fluorescent powder" or "α-cordierite: Ti ⁴⁺ " refers to the α-cordierite fluorescent powder obtained by doping with a titanium (IV)-containing activator . The term "Europium-activated α-cordierite fluorescent powder" or "α-cordierite: Eu ³⁺ " refers to the α-cordierite fluorescent powder obtained by doping an activator containing europium (III) . The term "cerium-activated α-cordierite fluorescent powder" or "α-cordierite: Ce ³⁺ " refers to the α-cordierite fluorescent powder obtained by doping a cerium (III)-containing activator .

[ step (1)]

Step (1) of the preparation method of the present invention is to prepare a precursor solution, and the precursor solution includes a starting solution and an activator. The starting solution comprises (a) a magnesium source selected from at least one of magnesium alkoxides and magnesium salts, (b) an aluminum source selected from at least one of aluminum alkoxides and aluminum salts, (c) selected from Silicon source and (d) solvent in silicon alkoxide. The activator is selected from manganese(II)-containing activators, chromium(III)-containing activators, titanium(IV)-containing activators, europium(III)-containing activators or cerium(III)-containing activators.

Among them, the magnesium alkoxide or the magnesium salt may be used alone, or the magnesium alkoxide and the magnesium salt may be used in combination. The magnesium alkoxide is, for example, but not limited to, magnesium methoxide [Mg(OCH ₃ ) ₂ ] or magnesium ethoxide [Mg(OC ₂ H ₅ ) ₂ ], and the above magnesium alkoxides can be used alone or in combination. The magnesium salt is, for example, but not limited to, magnesium nitrate [Mg(NO ₃ ) ₂ ]. In a specific embodiment of the present invention, the magnesium source is magnesium methoxide.

The aluminum alkoxide or the aluminum salt may be used alone, or the aluminum alkoxide and the aluminum salt may be used in combination. The aluminum alkoxide is, for example, but not limited to, aluminum isopropoxide [Al(Oi-Pr) ₃ ], and the aluminum salt is, for example, but not limited to, aluminum chloride (AlCl ₃ ). In particular embodiments of the present invention, the aluminum source is aluminum chloride.

The silicon alkoxide, such as but not limited to tetramethoxysilane [Si(OCH ₃ ) ₄ ] or tetraethoxy silane [Si(OC ₂ H ₅ ) ₄ ], the above silicon alkoxide can be used alone or in combination use. In a specific embodiment of the present invention, the silicon source is tetraethoxysilane.

The solvent is, for example, but not limited to, an alcoholic solvent. The alcohol solvent is, for example, but not limited to methanol or ethanol, and the above alcohol solvent can be used alone or in combination. In a specific embodiment of the present invention, the solvent is ethanol.

The manganese(II)-containing activator is at least one selected from the group consisting of manganese(II) chloride and manganese(II) nitrate. In particular embodiments of the present invention, the manganese(II)-containing activator is manganese(II) chloride.

The chromium(III)-containing activator is at least one selected from the group consisting of chromium(III) chloride and chromium(III) nitrate. In particular embodiments of the present invention, the chromium(III)-containing activator is chromium(III) chloride.

The titanium(IV)-containing activator is at least one selected from the group consisting of titanium(IV) isopropoxide and titanium tetrachloride. In a specific embodiment of the present invention, the titanium(IV)-containing activator is titanium(IV) isopropoxide.

The europium(III)-containing activator is at least one selected from the group consisting of europium(III) chloride and europium(III) nitrate. In particular embodiments of the present invention, the europium(III)-containing activator is europium(III) chloride.

The cerium (III)-containing activator is at least one selected from the group consisting of cerium (III) chloride and cerium (III) nitrate. In particular embodiments of the present invention, the cerium (III)-containing activator is cerium (III) chloride.

Preferably, in the step (1), the magnesium source, the aluminum source, the silicon source and the solvent are mixed to form the starting solution, one of the activators is added, and the precursor solution is formed after stirring and reacting. More preferably, in this step (1), the stirring is performed in a temperature range of 25-30°C. More preferably, in this step (1), the time range of the stirring is 1 to 2 hours.

Preferably, the molar ratio of the manganese (II)-containing activator to the magnesium source ranges from 1 to 20%. More preferably, the molar ratio of the manganese (II)-containing activator to the magnesium source is in the range of 1 to 5%, and the prepared α-cordierite fluorescent powder has high green light emission intensity. Optimally, the molar ratio of the manganese (II)-containing activator to the magnesium source is in the range of 2%, and the prepared α-cordierite fluorescent powder has the highest green light emission intensity.

Preferably, the molar ratio of the chromium (III)-containing activator to the magnesium source ranges from 1 to 20%. More preferably, the molar ratio of the chromium (III)-containing activator to the magnesium source ranges from 1 to 5%. Preferably, the molar ratio of the chromium (III)-containing activator to the magnesium source is 2%, and the prepared α-cordierite fluorescent powder has the highest red light emission intensity.

Preferably, the molar ratio of the titanium (IV)-containing activator to the magnesium source ranges from 1 to 20%. More preferably, the molar ratio of the titanium (IV)-containing activator to the magnesium source ranges from 1 to 5%. Preferably, the molar ratio of the titanium (IV)-containing activator to the magnesium source is 2%, and the prepared α-cordierite fluorescent powder has the highest blue light emission intensity.

Preferably, the molar ratio of the europium (III)-containing activator to the magnesium source ranges from 1 to 20%. More preferably, the molar ratio of the europium (III)-containing activator to the magnesium source ranges from 1 to 10%. Preferably, the molar ratio of the europium (III)-containing activator to the magnesium source is 6%, and the prepared α-cordierite fluorescent powder has the highest red light emission intensity.

Preferably, the molar ratio of the cerium (III)-containing activator to the magnesium source ranges from 1 to 20%. More preferably, the molar ratio of the cerium (III)-containing activator to the magnesium source is in the range of 1-5%, and the prepared α-cordierite fluorescent powder has high blue light emission intensity. Preferably, the molar ratio of the cerium (III)-containing activator to the magnesium source is 2%, and the prepared α-cordierite fluorescent powder has the highest blue light emission intensity.

[ step (2)]

The step (2) of the preparation method of the present invention is to add hydrochloric acid to the precursor solution and perform a hydrolysis reaction to obtain a transparent sol.

Preferably, the molar ratio of the hydrochloric acid to the magnesium source ranges from 0.3 to 0.5. If the molar ratio of the hydrochloric acid to the magnesium source is less than 0.3 or greater than 0.5, the resulting sol or gel will have low apparent transparency. In a specific embodiment of the present invention, the molar ratio of the hydrochloric acid to the magnesium source is 0.4.

Preferably, in this step (2), the hydrolysis reaction is performed in an environment with a temperature range of 25 to 30° C. and a relative humidity of 50 to 85% for 1 to 2 hours. In a specific embodiment of the present invention, the hydrolysis reaction is carried out in an environment of 25° C. for 2 hours.

[ step (3)]

The step (3) of the preparation method of the present invention is to perform a polycondensation reaction on the transparent sol to obtain a transparent gel.

Preferably, in this step (3), the polycondensation reaction is carried out in an environment with a temperature range of 25-30° C. and a relative humidity range of 50-85%. In a specific embodiment of the present invention, the polycondensation reaction is carried out in an environment with a temperature of 25° C. and a relative humidity of 55%.

In a specific embodiment of the present invention, the polycondensation reaction is carried out for 35 hours to 37.5 hours.

[ step (4)]

Step (4) of the preparation method of the present invention includes drying the transparent gel, and then performing a first annealing treatment at a temperature of 1300° C. to obtain the α-cordierite fluorescent powder.

In a specific embodiment of the present invention, the transparent gel is dried and refined into colloidal powder at a temperature of 120°C.

Preferably, in the step (4), the first annealing treatment is performed in an air atmosphere of 1300° C. for 2-6 hours.

Preferably, the step (4) further includes performing a second annealing treatment in a nitrogen-hydrogen mixed atmosphere at 1100° C. for 2 hours after the first annealing treatment, which can increase the manganese-activated α-cordierite fluoride obtained. Green light emission intensity and color saturation of light powder (α-cordierite: Mn ²⁺ ), and blue light emission intensity and color of cerium-activated α-cordierite fluorescent powder (α-cordierite: Ce ³⁺ ) saturation. And when the molar ratio of the manganese (II)-containing activator or the cerium (III)-containing activator and the magnesium source is 2%, the prepared α-cordierite fluorescent powder has the highest radiation intensity.

In some specific embodiments of the present invention, after the manganese-activated α-cordierite fluorescent powder (α-cordierite: Mn ²⁺ ) is excited by blue light with a wavelength of 450 nm, the emitted light is x of the CIE chromaticity coordinate The green light with the coordinate value in the range of 0.238~0.261 and the y-coordinate value in the range of 0.661~0.701.

In some specific embodiments of the present invention, after the chromium-activated α-cordierite fluorescent powder (α-cordierite: Cr ³⁺ ) is excited by blue-violet light with a wavelength of 398 nm, the emitted light is CIE chromaticity coordinates The red light with the x-coordinate value in the range of 0.7315~0.7319 and the y-coordinate value in the range of 0.2681~0.2685.

In some specific embodiments of the present invention, after the titanium-activated α-cordierite fluorescent powder (α-cordierite: Ti ⁴⁺ ) is excited by ultraviolet light with a wavelength of 265 nm, the emitted light is CIE chromaticity coordinates The blue light whose x-coordinate value is in the range of 0.151~0.168 and the y-coordinate value is in the range of 0.238~0.247.

In some specific embodiments of the present invention, after the europium-activated α-cordierite fluorescent powder (α-cordierite: Eu ³⁺ ) is excited by near-ultraviolet light with a wavelength of 393 nm, the emitted light is CIE chromaticity The red light with the x-coordinate value of the coordinates in the range of 0.583~0.605 and the y-coordinate value in the range of 0.362~0.381.

In some specific embodiments of the present invention, after the cerium-activated α-cordierite fluorescent powder (α-cordierite: Ce ³⁺ ) is excited by ultraviolet light with a wavelength of 316 nm, the emitted light is CIE chromaticity coordinates The blue light whose x-coordinate value is in the range of 0.150~0.156 and the y-coordinate value is in the range of 0.106~0.142.

The present invention will be further described with respect to the following examples, but it should be understood that the following examples are only used for illustration and should not be construed as a limitation of the implementation of the present invention.

"Preparation of Preparation Examples and Comparative Preparation Examples"

The preparation methods of the following preparation examples and comparative preparation examples include the steps described below: Step (1): in an environment of 25° C., dissolve 0.2 moles of magnesium methoxide, 0.4 moles of aluminum chloride and 0.5 moles of tetraethoxysilane in ethanol (solvent) and stir for 1 hour to form precursor fluid. Step (2): adding hydrochloric acid to the precursor solution, and performing a hydrolysis reaction at 25° C. and an environment with a relative humidity ranging from 50% to 85% for 2 hours to obtain a sol. Step (3): The sol is subjected to a polycondensation reaction at 25° C. and a relative humidity of 55% to obtain a gel.

"Preparation of Examples and Comparative Examples"

The preparation methods of the following examples and comparative examples include the steps described below: Step (1): in the environment of 25 ° C, take 0.2 mol of magnesium methoxide, 0.4 mol of aluminum chloride and 0.5 mol of tetraethoxysilane, dissolve in ethanol (solvent) and mix, and then add activation The reagents were mixed and stirred for 1 hour to form a precursor solution. Step (2): adding hydrochloric acid to the precursor solution and performing a hydrolysis reaction at 25° C. and in an environment with a relative humidity ranging from 50% to 85% for 2 hours to obtain a sol. Step (3): The sol is subjected to a polycondensation reaction at 25° C. and a relative humidity of 55% to obtain a gel. Step (4): the gel is dried at 120° C. and refined into colloidal powder. Next, the colloidal powder is subjected to a first annealing treatment at 1300° C. The colloidal powder subjected to the first annealing treatment is subjected to a second annealing treatment in a nitrogen-hydrogen mixed atmosphere at 1100° C. for 2 hours, and then cooled to room temperature after annealing to obtain a powder product.

Wherein, the molar ratio of hydrochloric acid and magnesium source in the preparation method of each preparation example and comparative preparation example, and the molar ratio of hydrochloric acid and magnesium source, the type and consumption of activator in the preparation method of each embodiment and comparative example, and The conditions of the annealing treatment are summarized in the following summary table.

General table Molar ratio of hydrochloric acid to magnesium source activator First Annealing Treatment ( Air Atmosphere ) Second annealing treatment ( nitrogen-hydrogen mixed atmosphere ) type Dosage (%) Temperature ( ℃ ) time ( hours ) Temperature ( ℃ ) time ( hours ) Example 1 0.4 Manganese chloride 1 1300 2 ― ― Example 2 0.4 Manganese chloride 2 1300 2 ― ― Example 3 0.4 Manganese chloride 3 1300 2 ― ― Example 4 0.4 Manganese chloride 6 1300 2 ― ― Example 5 0.4 Manganese chloride 10 1300 2 ― ― Example 6 0.4 Manganese chloride 20 1300 2 ― ― Example 7 0.4 Manganese chloride 1 1300 2 1100 2 Example 8 0.4 Manganese chloride 2 1300 2 1100 2 Example 9 0.4 Manganese chloride 3 1300 2 1100 2 Example 10 0.4 Manganese chloride 4 1300 2 1100 2 Example 11 0.4 Manganese chloride 5 1300 2 1100 2 Example 12 0.4 Manganese chloride 6 1300 2 1100 2 Example 13 0.4 Manganese chloride 8 1300 2 1100 2 Example 14 0.4 Manganese chloride 10 1300 2 1100 2 Example 15 0.4 Manganese chloride 20 1300 2 1100 2 Example 16 0.4 Chromium chloride 1 1300 2 ― ― Example 17 0.4 Chromium chloride 2 1300 2 ― ― Example 18 0.4 Chromium chloride 2 1300 4 ― ― Example 19 0.4 Chromium chloride 2 1300 6 ― ― Example 20 0.4 Chromium chloride 3 1300 2 ― ― Example 21 0.4 Chromium chloride 4 1300 2 ― ― Example 22 0.4 Chromium chloride 5 1300 2 ― ― Example 23 0.4 Chromium chloride 6 1300 2 ― ― Example 24 0.4 Chromium chloride 8 1300 2 ― ― Example 25 0.4 Chromium chloride 10 1300 2 ― ― Example 26 0.4 Chromium chloride 20 1300 2 ― ― Example 27 0.4 Titanium isopropoxide 1 1300 2 ― ― Example 28 0.4 Titanium isopropoxide 2 1300 2 ― ― Example 29 0.4 Titanium isopropoxide 2 1300 4 ― ― Example 30 0.4 Titanium isopropoxide 2 1300 6 ― ― Example 31 0.4 Titanium isopropoxide 3 1300 2 ― ― Example 32 0.4 Titanium isopropoxide 4 1300 2 ― ― Example 33 0.4 Titanium isopropoxide 5 1300 2 ― ― Example 34 0.4 Titanium isopropoxide 6 1300 2 ― ― Example 35 0.4 Titanium isopropoxide 8 1300 2 ― ― Example 36 0.4 Titanium isopropoxide 10 1300 2 ― ― Example 37 0.4 Titanium isopropoxide 20 1300 2 ― ― Example 38 0.4 Europium chloride 1 1300 2 ― ― Example 39 0.4 Europium chloride 2 1300 2 ― ― Example 40 0.4 Europium chloride 3 1300 2 ― ― Example 41 0.4 Europium chloride 4 1300 2 ― ― Example 42 0.4 Europium chloride 5 1300 2 ― ― Example 43 0.4 Europium chloride 6 1300 2 ― ― Example 44 0.4 Europium chloride 6 1300 4 ― ― Example 45 0.4 Europium chloride 6 1300 6 ― ― Example 46 0.4 Europium chloride 8 1300 2 ― ― Example 47 0.4 Europium chloride 10 1300 2 ― ― Example 48 0.4 Europium chloride 20 1300 2 ― ― Example 49 0.4 Cerium chloride 1 1300 2 ― ― Example 50 0.4 Cerium chloride 2 1300 2 ― ― Example 51 0.4 Cerium chloride 6 1300 2 ― ― Example 52 0.4 Cerium chloride 10 1300 2 ― ― Example 53 0.4 Cerium chloride 20 1300 2 ― ― Example 54 0.4 Cerium chloride 1 1300 2 1100 2 Example 55 0.4 Cerium chloride 2 1300 2 1100 2 Example 56 0.4 Cerium chloride 3 1300 2 1100 2 Example 57 0.4 Cerium chloride 4 1300 2 1100 2 Example 58 0.4 Cerium chloride 5 1300 2 1100 2 Example 59 0.4 Cerium chloride 6 1300 2 1100 2 Example 60 0.4 Cerium chloride 8 1300 2 1100 2 Example 61 0.4 Cerium chloride 10 1300 2 1100 2 Example 62 0.4 Cerium chloride 20 1300 2 1100 2 Comparative Example 1 0.4 Manganese chloride 0 1300 2 ― ― Comparative Example 2 0.4 Chromium chloride 0 1300 2 ― ― Comparative Example 3 0.4 Titanium isopropoxide 0 1300 2 ― ― Comparative Example 4 0.4 Europium chloride 0 1300 2 ― ― Comparative Example 5 0.4 Cerium chloride 0 1300 2 ― ― Preparation Example 1 0.3 ― ― ― ― ― ― Preparation Example 2 0.5 ― ― ― ― ― ― Comparative Preparation Example 1 0 ― ― ― ― ― ― Comparative Preparation Example 2 0.1 ― ― ― ― ― ― Comparative Preparation Example 3 0.2 ― ― ― ― ― ― Comparative Preparation Example 4 0.7 ― ― ― ― ― ― Comparative Preparation Example 5 1.0 ― ― ― ― ― ― Note 1: Amount of activator (%) = mol of activator ÷ mol of magnesium methoxide × 100%. Note 2: "-" means no addition or no execution.

"Sol and Gel Appearance State ( molar hydrochloride /Mg Moles of source = 0~1.0) 》

Table 1 Molar ratio of hydrochloric acid to magnesium source (moles of hydrochloric acid / moles of magnesium source ) Sol Appearance Gel Appearance Comparative Preparation Example 1 0 turbid white opaque Comparative Preparation Example 2 0.1 turbid white opaque Comparative Preparation Example 3 0.2 turbid translucent Preparation Example 1 0.3 clear transparent Preparation Example 2 0.5 clear transparent Comparative Preparation Example 4 0.7 turbid translucent Comparative Preparation Example 5 1.0 turbid white opaque

Referring to Table 1, it can be seen that hydrochloric acid is added in the preparation method and the molar ratio of hydrochloric acid and magnesium source is in the range of 0.3 to 0.5 (preparation examples 1 and 2), and the obtained sol has a clear appearance and a transparent gel appearance. However, do not add hydrochloric acid in the preparation method (compare preparation example 1), the molar ratio of hydrochloric acid and magnesium source is less than 0.3 (compare preparation examples 2~3), and the molar ratio of hydrochloric acid and magnesium source is greater than 0.5 (compare preparation example 4~ 5) The appearance of the prepared sol is turbid and the appearance of the gel is translucent or white opaque.

As can be seen from the above, hydrochloric acid is added in the preparation method, and the molar ratio of hydrochloric acid to magnesium source is in the range of 0.3 to 0.5, the appearance of the prepared sol is clear and the appearance of the gel is transparent, which proves that in the preparation method of the present invention, by adding an appropriate amount of hydrochloric acid can promote The gel is disintegrated and hydrolyzed uniformly, and then a transparent sol and a transparent gel can be obtained subsequently. In addition, hydrochloric acid is added in the preparation method of the present invention and the molar ratio of the hydrochloric acid to the magnesium source is in the range of 0.3 to 0.5, so even if an activator is used in the preparation method of the present invention, the appearance of the sol and gel will not be affected, and the prepared The sol is clear in appearance and the gel is transparent in appearance.

" X- light diffraction (X-ray diffraction , XRD) analyze"

The powder product was subjected to X-ray diffraction analysis using an X-ray diffractometer (manufacturer: Bruker, model: D8 Advance), and the obtained X-ray diffraction patterns are shown in Figures 1-5. 1 is the X-ray diffraction diagram of the powder products of Examples 1, 2, 4-6 and Comparative Example 1, and FIG. 2 is the powders of Examples 16-17, 23, 25-26 and Comparative Example 2 The X-ray diffraction diagram of the bulk product, FIG. 3 is the X-ray diffraction diagram of the powder products of Examples 27~28, 34, 36~37 and Comparative Example 3, and FIG. 4 is the X-ray diffraction diagram of Examples 38~39, 43 , 47-48 and the X-ray diffraction diagrams of the powder products of Comparative Example 4, FIG. 5 is the X-ray diffraction diagrams of the powder products of Examples 49-53 and Comparative Example 5.

Referring to FIGS. 1 to 5, it can be seen that even if different types and concentrations of activators are doped, the powder products obtained by annealing at 1300°C are all single-phase α-cordierite (α-Mg ₂ Al ₄ Si ₅ O ₁₈ ; JCPDS Card no. 13-0293), no other phases exist, indicating that Mn ²⁺ ions, Cr ³⁺ ions, Ti ⁴⁺ ions, Eu ³⁺ ions or Ce ³⁺ ions in the activator can be dissolved in α -Mg ₂ Al ₄ Si ₅ O ₁₈ in the host lattice. It should be added that after the first annealing treatment is performed in an air atmosphere of 1300°C, and then the second annealing treatment is performed in a nitrogen-hydrogen mixed atmosphere at 1100°C, the same result can also be obtained, that is, the obtained powder product. All are single-phase α-cordierite.

It should be added that if the annealing temperature is lower than 1300°C, the powder obtained will be accompanied by some heterogeneous phases, such as μ-cordierite (μ-Mg ₂ Al ₄ Si ₅ O ₁₈ ), magnesium aluminum spinel ( MgAl ₂ O ₄ ), mullite (Al ₆ SiO ₂ O ₁₃ ) and forsterite (Mg ₂ SiO ₄ ). In addition, when the annealing temperature is 1300°C and the annealing time is 6 hours, the diffraction peak intensity of α-Mg ₂ Al ₄ Si ₅ O ₁₈ is higher than that of the powder obtained by annealing for 2 hours. The product is higher, indicating that the crystallinity of the powder product obtained by increasing the annealing time is higher.

The average grain size of α-Mg ₂ Al ₄ Si ₅ O ₁₈ in each of the Examples and Comparative Examples in Tables 2 to 6 below is calculated according to the Scherrer equation.

Table 2 Amount of manganese chloride (%) α -Mg ₂ Al ₄ Si ₅ O ₁₈ average grain size (nm) Comparative Example 1 0 53.5 Example 1 1 53.8 Example 2 2 54.2 Example 4 6 54.6 Example 5 10 54.8 Example 6 20 55.5 Note: The amount of manganese chloride (%) = moles of manganese chloride ÷ moles of magnesium methoxide × 100%.

table 3 Chromium chloride dosage (%) α -Mg ₂ Al ₄ Si ₅ O ₁₈ average grain size (nm) Example 16 1 51.5 Example 17 2 50.5 Example 23 6 49.7 Example 25 10 49.0 Example 26 20 46.5 Note: Amount of chromium chloride (%) = moles of chromium chloride ÷ moles of magnesium methoxide × 100%.

Table 4 Amount of titanium isopropoxide (%) α -Mg ₂ Al ₄ Si ₅ O ₁₈ average grain size (nm) Example 27 1 52.6 Example 28 2 52.0 Example 34 6 51.2 Example 36 10 50.7 Example 37 20 50.3 Note: The amount of titanium isopropoxide (%) = the mole of titanium isopropoxide ÷ the mole of magnesium methoxide × 100%.

table 5 Europium chloride consumption (%) α -Mg ₂ Al ₄ Si ₅ O ₁₈ average grain size (nm) Example 38 1 55.4 Example 39 2 56.9 Example 43 6 57.8 Example 47 10 58.8 Example 48 20 61.2 Note: The amount of europium chloride (%) = moles of europium chloride ÷ moles of magnesium methoxide × 100%.

Table 6 Amount of Cerium Chloride (%) α -Mg ₂ Al ₄ Si ₅ O ₁₈ average grain size (nm) Example 49 1 54.1 Example 50 2 54.6 Example 51 6 56.3 Example 52 10 56.9 Example 53 20 57.8 Note: The amount of cerium chloride (%) = molar of cerium chloride ÷ molar of magnesium methoxide × 100%.

The results in Tables 2 to 6 show that when the types of activators are manganese (II) chloride, europium (III) chloride and cerium (III) chloride, the grain size of α-Mg ₂ Al ₄ Si ₅ O ₁₈ It increases with the increase of the amount of activator. When the type of activator is chromium(III) chloride and titanium(IV) isopropoxide, the grain size of α-Mg ₂ Al ₄ Si ₅ O ₁₈ decreases with the increase of the amount of activator.

"Scanning Electron Microscope (Scanning Electron Microscope , SEM) analyze"

The appearance of the powder product was analyzed by a scanning electron microscope (manufacturer: JEOL, model: JSM-7600F), and the obtained SEM photos are shown in Figures 6-10. 6 is the SEM photograph of Example 2, FIG. 7 is the SEM photograph of Example 17, FIG. 8 is the SEM photograph of Example 28, FIG. 9 is the SEM photograph of Example 39, and FIG. 10 is the SEM photograph of Example 50 photo.

Referring to Figures 6 to 10, it can be seen that the powder products prepared in the above-mentioned embodiments are all granular, wherein, the average primary particle size of the powder products of Example 2 (Figure 6) is about 55 nm, and Example 17 ( The average primary particle size of the powder product in Figure 7) is about 51 nm, the average primary particle size of the powder product in Example 28 (Figure 8) is about 52 nm, and the powder in Example 39 (Figure 9) is about 52 nm in size. The average primary particle size of the product is about 58 nm, and the average primary particle size of Example 50 (FIG. 10) is about 56 nm, indicating that the preparation method of the present invention can obtain α-cordierite fluoride with nanoparticle size. Light powder, and the average particle size of the powder varies slightly with the type of doping activator. Among them, the powder prepared by doping chromium (III) activator and titanium (IV) activator The average particle size of the powder is relatively fine, and the average particle size of the powder prepared by doping with manganese (II) activator, europium (III) activator and cerium (III) activator is larger, which is the same as the aforementioned "X". The analysis results obtained by "Light Diffraction Analysis" are consistent.

"Ultraviolet Light - visible light (UV-Visible Spectroscopy) Spectral Analysis"

The powder product was analyzed by a UV-Vis spectrometer (manufacturer: Hitachi, model: U3010), and the results obtained are shown in Figures 11-16.

It can be seen from Figure 11 that the powder product of Comparative Example 1 (without activator) has obvious absorption at the wavelength of 280 nm, and the absorption peak is around 220 nm, indicating that 220-300 nm is the main intrinsic absorption. The powder products of Examples 2, 4 and 5 (doped with manganese (II) activator) have intrinsic absorption at the wavelength of 300 nm, and obvious absorption can be observed at 350-550 nm, which is a typical electron During the transition between the ⁴ D energy level and the ⁴ G energy level of Mn ²⁺ ions, the absorption boundary of the powder product showed a red shift with the increase of the amount of manganese(II)-containing activator.

It can be seen from Figure 12 that the powder products of Examples 17, 23 and 25 (doped with chromium (III) activator) have significant absorption peaks at 400 nm and 558 nm in addition to the intrinsic absorption of the main body, which are typical electrons in Cr ^{3 +} ion ⁴ A ₂ → ⁴ T ₁ and ⁴ A ₂ → ⁴ T ₂ energy level transitions.

It can be seen from Figure 13 that the powder products of Examples 28, 34 and 36 (doped with a titanium (IV) activator) start to have obvious absorption around 380 nm, and show significant absorption after 250 nm, and the 450-600 nm band No characteristic absorption of Ti ⁴⁺ ions was observed, indicating that the absorption at 250~380 nm originates from the charge transfer transition of Ti ⁴⁺ ions.

From Figure 14, it can be seen that the powder products of Examples 39, 43 and 47 (doped with a europium (III) activator) have the intrinsic absorption of the main body, and obvious absorption peaks at 393 nm and 465 nm can be observed, which are typical The transition of electrons in Eu ³⁺ ions ⁷ F ₀ → ⁵ L ₆ and ⁷ F ₀ → ⁵ D ₂ energy levels.

It can be seen from Figure 15 that the powder products of Examples 50 to 52 (doped with cerium (III) activator) have obvious absorption at 400 nm, except for the intrinsic absorption of the main body, and show a significant absorption peak at 310 nm, which is typical The transition of electrons in the 4f–5d energy level of the Ce ³⁺ ion.

In addition, the energy gap value can be estimated according to the Tauc relation (αhν) ² = A(hν−Eg), where α is the absorption coefficient, A is the transition constant, Eg is the energy gap value, and hν is the energy of the incident photon, with ( αhν) ² and hv can be plotted to show the Tauc curve, and the intercept of the Tauc curve on the ordinate is the energy gap value Eg.

FIG. 16 shows Examples 2, 4, 5 and Comparative Example 1 (doping with a manganese (II)-containing activator), that is, the Tauc curve corresponding to FIG. 11 , and the results are summarized in Table 7 below. In a similar way, the above examples in Figures 12 to 15 were plotted using (αhν) ² and hv, respectively, and the results are summarized in Table 8 below.

Table 7 type of activator Activator dosage (%) Absorption sideband (nm) Energy gap value Eg(eV) Comparative Example 1 Manganese chloride 0 242.2 5.12 Example 1 Manganese chloride 1 243.1 5.10 Example 2 Manganese chloride 2 244.1 5.08 Example 4 Manganese chloride 6 251.5 4.93 Example 5 Manganese chloride 10 255.1 4.86 Example 6 Manganese chloride 20 255.7 4.85

Table 8 type of activator Activator dosage (%) Absorption sideband (nm) Energy gap value Eg(eV) Example 16 Chromium chloride 1 253.1 4.90 Example 17 Chromium chloride 2 254.1 4.88 Example 23 Chromium chloride 6 257.3 4.82 Example 25 Chromium chloride 10 258.9 4.79 Example 26 Chromium chloride 20 261.1 4.75 Example 27 Titanium isopropoxide 1 259.5 4.78 Example 28 Titanium isopropoxide 2 267.7 4.72 Example 34 Titanium isopropoxide 6 265.0 4.68 Example 36 Titanium isopropoxide 10 265.5 4.67 Example 37 Titanium isopropoxide 20 266.7 4.65 Example 38 Europium chloride 1 256.8 4.86 Example 39 Europium chloride 2 256.2 4.84 Example 43 Europium chloride 6 257.8 4.81 Example 47 Europium chloride 10 259.4 4.78 Example 48 Europium chloride 20 261.1 4.75 Example 49 Cerium chloride 1 252.5 4.91 Example 50 Cerium chloride 2 254.6 4.87 Example 51 Cerium chloride 6 255.7 4.85 Example 52 Cerium chloride 10 257.3 4.82 Example 53 Cerium chloride 20 258.3 4.80

It can be seen from Tables 7 and 8 that with the increase of the dosage of the activator, the absorption sidebands of the powder products all show a red shift, and the energy gap value decreases slightly.

"Fluorescence Spectrometer (Fluorescence spectroscopy) analyze"

The powder product was analyzed by a fluorescence spectrometer (manufacturer: Hitachi, model: F-7000), and the obtained results are shown in Figures 17-24.

< Analysis method 1: Photoluminescence analysis>

Measure embodiment 2 (activator is the manganese chloride of consumption 2%, in the air atmosphere of 1300 ℃ of annealing 2 hours) with fluorescence spectrometer, and embodiment 8 (activator is the manganese chloride of consumption 2%, in After annealing in an air atmosphere at 1300°C for 2 hours, and then annealing in a nitrogen-hydrogen mixed atmosphere at 1100°C for 2 hours), the excitation spectrum of photoluminescence in the wavelength range of 200~650 nm (Fig. 17) ) and emission spectra (Figure 18). The powder product obtained in Example 17 (the activator was 2% chromium chloride, annealed in an air atmosphere of 1300 ° C for 2 hours) was measured by a fluorescence spectrometer in the photoinduced wavelength range of 200-800 nm. Excitation and emission spectra of luminescence (Figure 19). Using a fluorescence spectrometer to measure the light in the wavelength range of 200-700 nm for the powder product obtained in Example 28 (activator is titanium isopropoxide with an amount of 2%, annealed in an air atmosphere of 1300 ° C for 2 hours) The excitation and emission spectra of the luminescence (Figure 20). The powder product obtained in Example 39 (the activator was 2% europium chloride in an amount of 2%, annealed in an air atmosphere of 1300 ° C for 2 hours) was measured by a fluorescence spectrometer in the photoinduced wavelength range of 200-650 nm. Excitation spectrum (FIG. 21) and emission spectrum (FIG. 22) of luminescence. Measured with a fluorescence spectrometer (the activator was 2% cerium chloride, annealed for 2 hours in an air atmosphere at 1300° C.), and Example 55 (the activator was 2% cerium chloride at 1300°C) After annealing in an air atmosphere at 1100°C for 2 hours, and then annealing in a nitrogen-hydrogen mixed atmosphere at 1100°C for 2 hours), the excitation spectrum of photoluminescence in the wavelength range of 200-650 nm (Fig. 23) and emission spectra (Figure 24).

It can be found from Figures 17 and 18 that the powder products of Examples 2 and 8 have significant excitation peaks at 360 nm, 384 nm, 426 nm and 450 nm, respectively, which are the ⁴ D and ⁴ G energies of typical electrons in Mn ²⁺ ions. Step transition, the peak 255 nm is the absorption of the main body, which is consistent with the results obtained in the aforementioned "ultraviolet light-visible light spectrum analysis", and the wavelength of the maximum excitation peak is 450 nm. Exciting the powder products of Examples 2 and 8 with excitation light with a wavelength of 450 nm (λ _ex = 450 nm) will both obtain a single emission peak with a wavelength of 514 or 520 nm, which originates from electrons at ⁴ of the Mn ²⁺ ions. It is caused by the transition of T ₁ → ⁶ A ₁ energy level, indicating that the manganese-activated α-cordierite fluorescent powder (α-cordierite: Mn ²⁺ ) prepared by the preparation method of the present invention can indeed emit a main emission peak. It is green light at 514~520 nm (λ _em = 514 nm or λ _em = 520 nm). In addition, compared with the powder product obtained by only performing the first annealing treatment in an air atmosphere in Example 2, Example 8 first performed the first annealing treatment in an air atmosphere, and then performed the first annealing treatment at 1100° C. in a nitrogen-hydrogen mixed atmosphere ( The powder product obtained by the second annealing treatment in a reducing atmosphere) has a higher luminescence intensity and will increase the crystallization field intensity of Mn ²⁺ ions, so the emission peak is red-shifted from 514 nm to 520 nm. It should be added that the powder products prepared by doping different amounts of manganese (II)-containing activators will obtain similar results, but the amount of manganese (II)-containing activators will affect the luminous intensity of the powder products. .

It can be found from Figure 19 that the powder product of Example 17 has obvious excitation peaks at wavelengths of 398 nm and 547 nm, which are the electrons in the Cr ³⁺ ions ⁴ A ₂ → ⁴ T ₁ and ⁴ A ₂ → ⁴ T ₂ , respectively. The transition of energy level is consistent with the results obtained in the aforementioned "ultraviolet light-visible light spectral analysis". After exciting the powder product of Example 17 with excitation light with a wavelength of 398 nm (λ _ex = 398 nm), a main emission peak with a wavelength of 696 nm (λ _em = 696 nm) will be obtained, which is the R line of Cr ³⁺ ions The characteristic wave shows that the chromium-activated α-cordierite fluorescent powder (α-cordierite: Cr ³⁺ ) obtained by the preparation method of the present invention can indeed emit red light with a main emission peak of 696 nm, and the half maximum wavelength (FWHM) is only 8nm, which means it has a narrow half-height width and good red light saturation. In addition, it can be found from Fig. 19 that there are weak emission peaks at the wavelengths of 676 nm and 710 nm, which are the characteristic waves of the R' line and the N line of the Cr ³⁺ ions respectively, indicating that the Cr ³⁺ ions are uniformly distributed, so R' The luminous intensity of the line and the N line is relatively weak. It should be added that the powder products prepared by doping different amounts of chromium (III)-containing activators will also obtain similar results, but the doping amount of chromium (III)-containing activators will affect the powder products. luminous intensity.

It can be found from Figure 20 that the powder product of Example 28 has an obvious excitation peak at a wavelength of 265 nm, mainly due to the absorption of Ti ⁴⁺ ions, which is consistent with the results obtained in the aforementioned "Ultraviolet-Visible Spectral Analysis". After exciting the powder product of Example 28 with excitation light with a wavelength of 265 nm (λ _ex = 265 nm), the emission wavelength range is between 350 and 650 nm, and the emission peak is 468 nm (λ _em = 468 nm), showing blue light. The emission characteristic, this broad emission band is consistent with the typical d ₀ complex ion luminescence characteristics, which is mainly caused by the transition of the luminescence center of the TiO ₆ complex. It is indicated that the titanium-activated α-cordierite fluorescent powder (α-cordierite: Ti ⁴⁺ ) obtained by the preparation method of the present invention can indeed emit blue light with a main emission peak of 468 nm. It should be added that the powder products prepared by doping different amounts of titanium (IV)-containing activator Ti will also obtain similar results, but the doping amount of titanium (IV)-containing activator will affect the powder. The luminescence intensity of the product.

It can be found from Figures 21 and 22 that the powder product of Example 39 has significant excitation peaks at 361 nm, 379 nm, 393 nm, 416 nm, 464 nm, 530 nm and 578 nm, which are typical electrons in Eu ³⁺ ions. The transition of the f–f energy level, and the intrinsic absorption of the excitation wave less than 300 nm is the main body, which is consistent with the results obtained in the aforementioned "ultraviolet-visible light spectral analysis". After exciting the powder product of Example 39 with excitation light with a wavelength of 393 nm (λ _ex = 393 nm), a main radiation wave with a peak of 616 nm (λ _em = 616 nm) is obtained, which is the electron in the Eu ³⁺ ion. The transition of ⁵ D ₀ → ⁷ F ₂ energy level, in addition, there are weak emission peaks around 579 nm and 590 nm, which are ⁵ D ₀ → ⁷ F ₀ and ⁵ D ₀ → ⁷ F ₁ of Eu ³⁺ ions, respectively energy level transition. It shows that the europium-activated α-cordierite fluorescent powder (α-cordierite: Eu ³⁺ ) obtained by the preparation method of the present invention can indeed emit red light with a main emission peak of 616 nm. It should be added that the powder products prepared by doping different amounts of europium (III)-containing activators will also obtain similar results, but the doping amount of europium (III)-containing activators will affect the powder products. luminous intensity.

From Figures 23 and 24, it can be found that after simulation with wavelengths of 392 nm and 420 nm, respectively, the powder products of Examples 50 and 55 have significant excitation peaks at 310 nm and 316 nm, which are typical electrons at 4f of Ce ³⁺ ions. The transition of -5d is consistent with the results obtained in the aforementioned "ultraviolet-visible light spectral analysis". The powder products of Examples 50 and 55 were excited by excitation light (λ _ex = 310 nm and λ _ex = 316 nm) with wavelengths of 310 and 316 nm, respectively, and single emission waves (λ ex = 310 nm and λ ex = 316 nm) with peaks at 392 nm and 420 nm were obtained. _em = 392 nm and λ _em = 420 nm), which originates from the transition of electrons at the 5d→2F _7/2 and 5d→2F _5/2 energy levels of Ce ³⁺ ions. The powder product obtained by the first annealing treatment in an air atmosphere, in Example 55, the first annealing treatment was carried out in an air atmosphere, and then the second annealing treatment was carried out at 1100° C. and a nitrogen-hydrogen mixed atmosphere (reducing atmosphere). The obtained powder product has higher luminous intensity, and will increase the crystallization field intensity of Ce ³⁺ ions, so the emission peak is red-shifted from 392 nm to 420 nm, indicating that the cerium-activated α-cordium obtained by the preparation method of the present invention The bluestone phosphor (α-cordierite: Ce ³⁺ ) can indeed emit blue light (λ _em = 420 nm) with a main emission peak at 420 nm. It should be added that the powder products prepared by doping different amounts of cerium (III)-containing activators will obtain similar results, but the doping amount of cerium (III)-containing activators will affect the powder products. light intensity.

< Analysis method 2: luminous intensity and decay time ( afterglow ) analyze>

The relative luminescence intensity (normalized emission intensity) and decay time (afterglow) of the powder product at the main emission peak (λ _em ) were measured by the fluorescence spectrometer. The results obtained are shown in Figures 25-28 and Tables 9-13.

Table 9 Amount of manganese chloride (%) Relative intensity (λ _em = 520 nm) Decay time (ms) (λ _em = 520 nm) First Annealing Treatment ( Air Atmosphere ) Second annealing treatment ( nitrogen-hydrogen mixed atmosphere ) Temperature ( ℃ ) time ( hours ) Temperature ( ℃ ) time ( hours ) Example 1 1 0.22 5.6 1300 2 ― ― 2 2 0.27 4.1 1300 2 ― ― 3 3 0.18 3.7 1300 2 ― ― 7 1 0.72 5.5 1300 2 1100 2 8 2 1.0 4.2 1300 2 1100 2 9 3 0.82 3.7 1300 2 1100 2 10 4 0.78 3.5 1300 2 1100 2 11 5 0.66 3.4 1300 2 1100 2 12 6 0.58 3.3 1300 2 1100 2 13 8 0.47 3.3 1300 2 1100 2 14 10 0.45 3.2 1300 2 1100 2 15 20 0.38 2.8 1300 2 1100 2

Table 10 Chromium chloride dosage (%) Relative intensity (λ _em = 520 nm) Decay time (ms) (λ _em = 696 nm) First Annealing Treatment ( Air Atmosphere ) Second annealing treatment ( nitrogen-hydrogen mixed atmosphere ) Temperature ( ℃ ) time ( hours ) Temperature ( ℃ ) time ( hours ) Example 16 1 0.66 4.2 1300 2 ― ― 17 2 0.88 4.0 1300 2 ― ― 18 2 0.93 4.0 1300 4 ― ― 19 2 1.0 3.9 1300 6 ― ― 20 3 0.77 3.6 1300 2 ― ― twenty one 4 0.72 2.8 1300 2 ― ― twenty two 5 0.67 2.2 1300 2 ― ― twenty three 6 0.55 1.9 1300 2 ― ― twenty four 8 0.46 1.5 1300 2 ― ― 25 10 0.38 1.2 1300 2 ― ― 26 20 0.32 1.1 1300 2 ― ―

Table 11 Amount of titanium isopropoxide (%) Relative intensity (λ _em = 520 nm) Decay time (ms) (λ _em = 468 nm) First Annealing Treatment ( Air Atmosphere ) Second annealing treatment ( nitrogen-hydrogen mixed atmosphere ) Temperature ( ℃ ) time ( hours ) Temperature ( ℃ ) time ( hours ) Example 27 1 0.72 0.88 1300 2 ― ― 28 2 0.89 0.86 1300 2 ― ― 29 2 0.92 0.85 1300 4 ― ― 30 2 1.0 0.86 1300 6 ― ― 31 3 0.86 0.82 1300 2 ― ― 32 4 0.77 0.81 1300 2 ― ― 33 5 0.55 0.79 1300 2 ― ― 34 6 0.48 0.78 1300 2 ― ― 35 8 0.34 0.77 1300 2 ― ― 36 10 0.31 0.76 1300 2 ― ― 37 20 0.25 0.75 1300 2 ― ―

Table 12 Europium chloride consumption (%) Relative intensity (λ _em = 520 nm) Decay time (ms) (λ _em = 616 nm) First Annealing Treatment ( Air Atmosphere ) Second annealing treatment ( nitrogen-hydrogen mixed atmosphere ) Temperature ( ℃ ) time ( hours ) Temperature ( ℃ ) time ( hours ) Example 38 1 0.56 2.2 1300 2 ― ― 39 2 0.68 2.1 1300 2 ― ― 40 3 0.82 2.0 1300 2 ― ― 41 4 0.74 1.9 1300 2 ― ― 42 5 0.83 1.8 1300 2 ― ― 43 6 0.90 1.7 1300 2 ― ― 44 6 0.95 1.7 1300 4 ― ― 45 6 1.0 1.6 1300 6 ― ― 46 8 0.76 1.6 1300 2 ― ― 47 10 0.58 1.6 1300 2 ― ― 48 20 0.39 1.5 1300 2 ― ―

Table 13 Cerium chloride dosage (mol%) Relative intensity (λ _em = 520 nm) Decay time (ms) (λ _em = 420 nm) First Annealing Treatment ( Air Atmosphere ) Second annealing treatment ( nitrogen-hydrogen mixed atmosphere ) Temperature ( ℃ ) time ( hours ) Temperature ( ℃ ) time ( hours ) Example 54 1 0.88 <0.1 1300 2 1100 2 55 2 1.0 <0.1 1300 2 1100 2 56 3 0.86 <0.1 1300 2 1100 2 57 4 0.75 <0.1 1300 2 1100 2 58 5 0.61 <0.1 1300 2 1100 2 59 6 0.52 <0.1 1300 2 1100 2 60 8 0.43 <0.1 1300 2 1100 2 61 10 0.36 <0.1 1300 2 1100 2 62 20 0.32 <0.1 1300 2 1100 2

From Figures 25 to 28 and Tables 9 to 13, it can be found that regardless of the amount of activator), the obtained powder products have the characteristics of short afterglow, and the ambient atmosphere of the annealing treatment has no effect on the decay time of the powder products. obvious impact. It is particularly worth mentioning that the powder products prepared by doping with manganese(II)-containing activator are compared with the powder products prepared by only performing the first annealing treatment in an air atmosphere (Example 1~3), the powder products (Examples 7~15) obtained by performing the first annealing treatment in an air atmosphere and then performing the second annealing treatment in a nitrogen-hydrogen mixed atmosphere (reducing atmosphere) will emit light. The intensity of green light (λ _em = 520 nm) was significantly increased, and the powder product prepared with a manganese(II)-containing activator amount (Mn ²⁺ /Mg) of 2% had the best luminous intensity. The powder products prepared by doping with cerium (III)-containing activator also have similar results, first annealing in air atmosphere and then second annealing in nitrogen-hydrogen mixed atmosphere (reducing atmosphere). The radiation of the obtained powder products (Examples 54~62) will significantly increase the intensity of blue light (λ _em = 420 nm), and the amount of cerium (III) activator (Ce ³⁺ /Mg) is 2%. The obtained powder product (Example 55) had the best luminous intensity. In addition, the powder product (Example 19) prepared with a chromium (III)-containing activator amount (Cr ³⁺ /Mg) of 2% and the first annealing treatment time of 6 hours had the best red light (Example 19). λ _em = 696 nm) luminescence intensity. The powder product (Example 30) prepared with a titanium (IV)-containing activator dosage (Ti ⁴⁺ /Mg) of 2% and a first annealing treatment time of 6 hours has the best blue light (λ _em = 468 nm) luminescence intensity. The powder product (Example 45) prepared with a Europium (III) activator dosage (Eu ³⁺ /Mg) of 6% and the first annealing treatment time of 6 hours has the best red light (λ _em = 616 nm) luminescence intensity.

" CIE Chromaticity diagram (CIE chromaticity diagram) analyze"

After the powder product to be tested is excited by a specific excitation light, the luminescence spectrum measured by a fluorescence spectrometer is calculated according to the standard three primary colors and three excitation values formulated by the International Commission on Illumination (CIE). The emission spectrum is converted into a chromaticity coordinate (X, Y) value, that is, the CIE 1931 chromaticity coordinate obtained after the powder product is excited by a specific excitation light is obtained. Among them, the CIE 1931 chromaticity coordinates of Examples 1, 2, 8, 12 and 14-15 obtained after being excited by excitation light with a wavelength of 450 nm are shown in Figure 29; The CIE 1931 chromaticity coordinates obtained after excitation with excitation light with a wavelength of 398 nm are shown in Figure 30; the CIE 1931 chromaticity coordinates obtained in Examples 27~28, 34, 36~37 after excitation with excitation light with a wavelength of 265 nm As shown in Figure 31; the CIE 1931 chromaticity coordinates of Examples 38-39, 43 and 47-48 after being excited by excitation light with a wavelength of 393 nm are shown in Figure 32; Examples 49, 54-55, 59 and Figure 33 shows the CIE 1931 chromaticity coordinates of 61~62 after being excited by excitation light with a wavelength of 316 nm. The CIE chromaticity coordinates (X, Y) values in Figures 29-33 are shown in Table 14 below, which can be used to identify the relative relationship between the luminous color purity of the powder product and other colors of visible light.

Table 14 Example Type and dosage of activator Second Annealing Treatment λ _ex = 450 nm emission color CIE chromaticity coordinates (x,y) 1 Manganese chloride 1 % ― green light 0.241, 0.661 2 Manganese chloride 2 % green light 0.238, 0.675 8 Manganese chloride 2 % Nitrogen-hydrogen mixed atmosphere 1100℃ for 2 hours green light 0.245, 0.701 12 Manganese chloride 6 % green light 0.248, 0.695 14 Manganese chloride 10 % green light 0.250, 0.683 15 Manganese chloride 20 % green light 0.261, 0.669 Example Type and dosage of activator Second Annealing Treatment λ _ex = 398 nm emission color CIE chromaticity coordinates (x,y) 16 Chromium chloride 1 % ― red light 0.7319, 0.2681 17 Chromium chloride 2 % red light 0.7317, 0.2683 twenty three Chromium chloride 6 % red light 0.7316, 0.2684 25 Chromium chloride 10 % red light 0.7315, 0.2685 26 Chromium chloride 20 % red light 0.7318, 0.2684 Example Type and dosage of activator Second Annealing Treatment λ _ex = 265 nm emission color CIE chromaticity coordinates (x,y) 27 Titanium isopropoxide 1 % ― Blu-ray 0.168, 0.242 28 Titanium isopropoxide 2 % Blu-ray 0.153,0.240 34 Titanium isopropoxide 6 % Blu-ray 0.151, 0.243 36 Titanium isopropoxide 10 % Blu-ray 0.152, 0.247 37 Titanium isopropoxide 20 % Blu-ray 0.166,0.238 Example Type and dosage of activator Second Annealing Treatment λ _ex = 393 nm emission color CIE chromaticity coordinates (x,y) 38 Europium chloride 1 % ― red light 0.583, 0.381 39 Europium chloride 2 % red light 0.596, 0.372 43 Europium chloride 6 % red light 0.598, 0.365 47 Europium chloride 10 % red light 0.605, 0.362 48 Europium chloride 20 % red light 0.586, 0.367 Example Type and dosage of activator Second Annealing Treatment λ _ex = 316 nm emission color CIE chromaticity coordinates (x,y) 49 Cerium chloride 1 % ― blue-violet light 0.156, 0.038 54 Cerium chloride 1 % Nitrogen-hydrogen mixed atmosphere 1100℃ for 2 hours Blu-ray 0.153, 0.106 55 Cerium chloride 2 % Blu-ray 0.150, 0.107 59 Cerium chloride 6 % Blu-ray 0.151, 0.112 61 Cerium chloride 10 % Blu-ray 0.152, 0.138 62 Cerium chloride 20 % Blu-ray 0.156, 0.142 Note: "-" indicates that only the first annealing treatment (air atmosphere, 1300°C, 2 hours) was performed, but the second annealing treatment was not performed.

It can be found from Figures 29 to 33 and Table 14 that the CIE chromaticity coordinates of Examples 1, 2, 8, 12 and 14 to 15 are all the CIE chromaticity coordinates with green light emission characteristics (x=0.238 to 0.261, y=0.661~0.701); the CIE chromaticity coordinates of Examples 16~17, 23 and 25~26 are all within the CIE chromaticity coordinates with red light emission characteristics (x=0.7315~0.7319, y=0.2681~ 0.2685) within the scope; the CIE chromaticity coordinate values of Examples 27~28, 34, 36~37 are all within the CIE chromaticity coordinate value (x=0.151~0.168, y=0.238~0.247) with blue light emission characteristics; The CIE chromaticity coordinates of Examples 38 to 39, 43 and 47 to 48 are all within the CIE chromaticity coordinates of red light emission characteristics (x=0.583 to 0.605, y=0.362 to 0.381); The CIE chromaticity coordinates (x=0.156, y=0.038) have blue-violet emission characteristics, and the CIE chromaticity coordinates of Examples 54~55, 59 and 61~62 are all CIE chromaticity coordinates with blue emission characteristics. (x=0.150~0.156, y=0.106~0.142).

To sum up, since the preparation method of the present invention uses specific magnesium sources, aluminum sources and silicon sources, it can naturally form gelation through polycondensation reaction, and can maintain the close and uniform distribution of the constituent molecules, so that the α-cordierite can be improved. In addition, a specific amount of hydrochloric acid (the molar ratio of hydrochloric acid to magnesium source is in the range of 0.3 to 0.5) is added as a dissolving aid in the process, so that the hydrolysis reaction can be promoted to greatly improve the dispersibility and homogeneity of the generated sol. Therefore, the obtained α-cordierite has high reproducibility, high stability, no segregation phase and smaller average particle size. Adding a specific type of the activator to carry out the hydrolysis reaction, and performing the first annealing treatment at a temperature of 1300°C, green light (α-cordierite: Mn ²⁺ ) and red light (α-cordierite) can be obtained respectively. : Cr ³⁺ , α-cordierite: Eu ³⁺ ) or blue light (α-cordierite: Ti ⁴⁺ , α-cordierite: Ce ³⁺ ) α-cordierite fluorescent powder with radiation characteristics. In addition, after the first annealing treatment, the second annealing treatment is performed in a nitrogen-hydrogen mixed atmosphere at 1100° C., which can improve the radiation intensity and stability of the α-cordierite phosphor powder. Therefore, the object of the present invention can be achieved indeed.

However, the above are only examples of the present invention, and should not limit the scope of the present invention. Any simple equivalent changes and modifications made according to the scope of the application for patent of the present invention and the content of the patent specification are still within the scope of the present invention. within the scope of the invention patent.

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: [Fig. 1] is Example 1, 2, 4~6 and Comparative Example 1 (activator is 0~20mol% manganese chloride, annealed in an air atmosphere of 1300 ° C for 2 hours) X-ray diffraction diagram of the powder product; (The activator is 0-20mol% chromium chloride, annealed in an air atmosphere at 1300°C for 2 hours) The X-ray diffraction pattern of the powder product; [Fig. 3] are examples 27-28, 34 , 36~37 and Comparative Example 3 (activator is titanium isopropoxide with an amount of 0~20%, annealed in an air atmosphere of 1300 ° C for 2 hours) The X-ray diffraction patterns of the powder products; [Fig. 4] It is the powder products obtained in Examples 38-39, 43, 47-48 and Comparative Example 4 (the activator is europium chloride with an amount of 0-20%, annealed in an air atmosphere of 1300 ° C for 2 hours). X-ray diffraction pattern; [Fig. 5] is the powder obtained from Examples 49~53 and Comparative Example 5 (the activator is cerium chloride with an amount of 0~20%, annealed in an air atmosphere of 1300 ° C for 2 hours). The X-ray diffraction pattern of the bulk product; [Fig. 6] is the SEM photo of the powder product obtained in Example 2 (the activator is manganese chloride with a dosage of 2%, annealed in an air atmosphere of 1300 ° C for 2 hours). ; [Fig. 7] is the SEM photograph of the powder product obtained in Example 17 (activator is 2% chromium chloride, annealed in an air atmosphere of 1300°C for 2 hours); [Fig. 8] is Example 28 (The activator is titanium isopropoxide with a dosage of 2%, and annealed in an air atmosphere of 1300 ° C for 2 hours) The SEM photo of the powder product; [Fig. 9] is Example 39 (the activator is with a dosage of 2%). SEM photo of the powder product prepared by europium chloride, annealed at 1300°C for 2 hours in air atmosphere; [Fig. 10] is Example 50 (activator is 2% cerium chloride, 1300°C air atmosphere) SEM photos of the powder products prepared by annealing for 2 hours in the middle; [Fig. 11] are Examples 2, 4, 5 and Comparative Example 1 (the activator is manganese chloride with an amount of 0-10%, and the air temperature is 1300°C). The ultraviolet-visible light spectrum of the powder product obtained by annealing in the atmosphere for 2 hours); [Fig. 12] is Example 17, 23 and 25 (the activator is chromium chloride with an amount of 2~10%, 1300 ℃) The UV-Vis spectrum of the powder product obtained by annealing in an air atmosphere for 2 hours; [Figure 13] is Example 28, 34 and 36 (the activator is titanium isopropoxide with an amount of 2~10%, 1300 ℃ The ultraviolet-visible light spectrum of the powder product obtained by annealing in the air atmosphere of 2 hours for 2 hours; [Fig. 14] is Example 39, 43 and 47 (the activator is europium chloride with a dosage of 2~10%, 1300 ℃ The UV-Vis spectrum of the powder product obtained by annealing in an air atmosphere of 2 hours; [Figure 15] is Example 5 0~52(The activator is 2~10% cerium chloride, and the ultraviolet-visible light spectrum of the powder product obtained by annealing in an air atmosphere of 1300 ° C for 2 hours; [Figure 16] is Example 2, 4, 5 and Comparative Example 1 (the activator is manganese chloride with an amount of 0~10%, annealed in an air atmosphere of 1300 ° C for 2 hours) (αhν) ² -hv curve diagram of the powder product; [Fig. 17] is Example 2 (activator is manganese chloride with a dosage of 2%, annealed for 2 hours in an air atmosphere of 1300 ° C), and Example 8 (the activator is manganese chloride with a dosage of 2 %, and an air atmosphere of 1300 ° C) After annealing in medium for 2 hours, and then annealing in a nitrogen-hydrogen mixed atmosphere at 1100°C for 2 hours), the excitation spectrum of the powder products obtained; [Fig. 18] is the emission of the powder products obtained in Examples 2 and 8. spectrum; [Fig. 19] is the excitation spectrum and emission spectrum of the powder product prepared in Example 17 (activator is 2% chromium chloride, annealed in an air atmosphere at 1300°C for 2 hours); [Fig. 20] It is the excitation spectrum and emission spectrum of the powder product obtained in Example 28 (activator is titanium isopropoxide with a dosage of 2%, annealed in an air atmosphere of 1300 ° C for 2 hours); [Figure 21] is Example 39 ( The excitation spectrum of the powder product prepared by using 2% europium chloride as the activator and annealing in an air atmosphere of 1300°C for 2 hours); [Fig. 22] is Example 39 (the activator is 2% chlorinated chloride). The emission spectrum of the powder product prepared by europium, annealed in an air atmosphere of 1300 ℃ for 2 hours); [Fig. 23] is Example 50 (the activator is 2% cerium chloride, annealed in an air atmosphere of 1300 ℃) 2 hours), and the powder product obtained in Example 55 (the activator is 2% cerium chloride, annealed in an air atmosphere at 1300°C for 2 hours, and annealed in a nitrogen-hydrogen mixed atmosphere at 1100°C for 2 hours) The excitation spectrum of ; [Figure 24] is the emission spectrum of the powder products prepared in Examples 50 and 55; [Figure 25] is the attenuation of the powder products prepared in Examples 1, 2, 4, 5 and 6 Graph; [Fig. 26] is the attenuation curve of the powder products prepared in Examples 16-17, 23 and 25-26; [Fig. 27] is the powder obtained in Examples 27-28 and 34-37 The attenuation curve of the bulk product; [Fig. 28] is the attenuation curve of the powder product prepared in Examples 38, 42, 47 and 48; [Fig. 29] is the attenuation curve of Examples 1, 2, 8, 12 and 14~ 15 CIE chromaticity diagram of the powder products prepared; [Fig. 30] is the CIE chromaticity diagram of the powder products prepared in Examples 16-17, 23 and 25-26; [Fig. 31] is an example The CIE chromaticity diagram of the powder products prepared from 27~28, 34, 36~37; [Figure 32] is the CIE chromaticity diagram of the powder products prepared in Examples 38~39, 43 and 47~48 ; and [FIG. 33] are Examples 49, 54~55, 59 and 61~6 2 The CIE chromaticity diagram of the powder product obtained.

Claims (10)

A method for preparing α-cordierite fluorescent powder, comprising the following steps: (1) preparing a precursor solution, the precursor solution comprising a starting solution and an activator, the starting solution comprising (a) selected from magnesium alkoxide and at least one magnesium source of magnesium salt, (b) aluminum source selected from at least one of aluminum alkoxide and aluminum salt, (c) silicon source selected from silicon alkoxide, and (d) solvent, the activation The agent is selected from manganese(II)-containing activators, chromium(III)-containing activators, titanium(IV)-containing activators, europium(III)-containing activators or cerium(III)-containing activators; (2) in the Add hydrochloric acid to the precursor solution and carry out a hydrolysis reaction to obtain a transparent sol, wherein the molar ratio of the hydrochloric acid to the magnesium source ranges from 0.3 to 0.5; (3) The transparent sol is subjected to a polycondensation reaction to obtain a transparent gel and (4) drying the transparent gel and performing a first annealing treatment at a temperature of 1300° C. to obtain α-cordierite fluorescent powder, and the experimental formula of the α-cordierite fluorescent powder is α -Mg ₂ Al ₄ Si ₅ O ₁₈ : xM, M represents Mn ²⁺ , Cr ³⁺ , Ti ⁴⁺ , Eu ³⁺ or Ce ³⁺ , x=[M]/[Mg]=1~20%. The preparation method of α-cordierite fluorescent powder as claimed in claim 1, wherein, in the step (1), the molar ratio of the activator to the magnesium source ranges from 1 to 20%, and the manganese-containing (II) the activator is at least one selected from the group consisting of manganese(II) chloride and manganese(II) nitrate, and the chromium(III)-containing activator is selected from chromium(III) chloride and At least one of the group consisting of chromium (III) nitrate, the titanium (IV)-containing activator is at least one selected from the group consisting of titanium (IV) isopropoxide and titanium tetrachloride, the The europium(III)-containing activator is at least one selected from the group consisting of europium(III) chloride and europium(III) nitrate, and the cerium(III)-containing activator is selected from cerium(III) chloride ) and at least one of the group consisting of cerium (III) nitrate. The method for preparing α-cordierite fluorescent powder according to claim 1, wherein, in the step (1), when the activator is selected from manganese (II)-containing activators, the manganese (II)-containing activator II) The molar ratio range of the activator to the magnesium source is 2%; when the activator is selected from a chromium(III)-containing activator, the molar ratio of the chromium(III)-containing activator to the magnesium source The range is 2%; when the activator is selected from the titanium (IV)-containing activator, the molar ratio of the titanium (IV)-containing activator to the magnesium source is in the range of 2%; when the activator is selected from When containing a europium (III) activator, the molar ratio of the europium (III) containing activator to the magnesium source is 6%; when the activating agent is selected from a cerium (III) containing activator, the containing The molar ratio of cerium(III) activator to the magnesium source was in the range of 2 %. The method for preparing α-cordierite fluorescent powder according to claim 1, wherein, in the step (4), the first annealing treatment is performed in an air atmosphere of 1300° C. for 2 to 6 hours. The method for preparing α-cordierite fluorescent powder according to claim 1, wherein in the step (4), it further comprises, after the first annealing treatment, performing a second annealing treatment in a nitrogen-hydrogen mixed atmosphere at 1100° C. Annealed for 2 hours. The method for preparing α-cordierite fluorescent powder according to claim 1, wherein in the step (1), the activator is selected from manganese (II)-containing activators, and in the step (4) The experimental formula of the obtained α-cordierite fluorescent powder is α-Mg ₂ Al ₄ Si ₅ O ₁₈ : xMn ²⁺ , and the main emission peak of the α-cordierite fluorescent powder is 514-520 nm , the decay time is less than 5.6 ms, and the green emission light with CIE chromaticity coordinates in the range of x=0.238~0.261 and y=0.661~0.701 is generated after excitation by the excitation light with a wavelength of 450 nm. The preparation method of α-cordierite fluorescent powder as claimed in claim 1, wherein, in the step (1), the activator is selected from chromium (III)-containing activators, and in the step (4) The experimental formula of the obtained α-cordierite fluorescent powder is α-Mg ₂ Al ₄ Si ₅ O ₁₈ : xCr ³⁺ , and the main emission peak of the α-cordierite fluorescent powder is 696 nm, half The high wavelength width is 8 nm and the decay time is less than 4.2 ms, and after being excited by the excitation light with a wavelength of 398 nm, it will produce red emission light with CIE chromaticity coordinates in the range of x=0.7315~0.7319 and y=0.2681~0.2685. The method for preparing α-cordierite fluorescent powder according to claim 1, wherein in the step (1), the activator is selected from titanium (IV)-containing activators, and in the step (4) The experimental formula of the obtained α-cordierite fluorescent powder is α-Mg ₂ Al ₄ Si ₅ O ₁₈ : xTi ⁴⁺ , and the main emission peak of the α-cordierite fluorescent powder is 468 nm, and the attenuation The time is less than 0.88 ms, and after being excited by excitation light with a wavelength of 265 nm, blue emission light with CIE chromaticity coordinates in the range of x=0.151~0.168 and y=0.238~0.247 is generated. The preparation method of α-cordierite fluorescent powder according to claim 1, wherein, in the step (1), the activator is selected from activators containing europium (III), and in the step (4) The experimental formula of the obtained α-cordierite fluorescent powder is α-Mg ₂ Al ₄ Si ₅ O ₁₈ : xEu ³⁺ , and the main emission peak of the α-cordierite fluorescent powder is 616 nm, and the attenuation The time is less than 2.2 ms, and the red emission light with CIE chromaticity coordinates in the range of x=0.583~0.605 and y=0.362~0.381 is generated after being excited by the excitation light with a wavelength of 393 nm. The preparation method of α-cordierite fluorescent powder according to claim 1, wherein in the step (1), the activator is selected from cerium (III)-containing activators, and in the step (4) The experimental formula of the obtained α-cordierite fluorescent powder is α-Mg ₂ Al ₄ Si ₅ O ₁₈ : xCe ³⁺ , and the main emission peak of the α-cordierite fluorescent powder is 420 nm, and the attenuation The time is less than 0.1 ms, and after being excited by the excitation light with a wavelength of 316 nm, blue emission light with CIE chromaticity coordinates in the range of x=0.150~0.156 and y=0.106~0.142 is generated.

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