A double perovskite luminescent material for LED lighting and information encryption and a preparation method thereof

Abstract

The application provides a double perovskite luminescent material which can be used for LED lighting and information encryption, and has a chemical formula of [Rb 1‑x (NH4) x ]2SnCl6:yBi 3+ , wherein 0

Description

Technical Field

[0001] The present invention belongs to the technical field of luminescent materials, and particularly relates to a double perovskite luminescent material that can be used for LED lighting and information encryption, and also relates to a preparation method of the above double perovskite luminescent material. Background Art

[0002] In the fields of LED lighting and information encryption, metal halide perovskite materials have great application potential because of their simple preparation and easy realization of efficient and tunable light emission. In recent years, Cs2SnCl6:Bi reported in the literature 3+ phosphors have attracted great attention due to their excellent luminescent properties such as high fluorescence quantum yield and wide emission band.

[0003] However, although the above materials can achieve very ideal blue light emission, Bi 3+ doping in such 216-structured perovskites cannot achieve tuning of the emission spectrum, and this defect restricts the application of such materials in LED lighting and information encryption. On the other hand, in the preparation process of the reported single crystal / microcrystal materials, growing single crystals requires a large amount of time, which will greatly increase the energy consumption and time cost in the production process.

[0004] Based on this, how to achieve tunable emission spectrum of Bi 3+ doped 216-structured perovskites to meet the application requirements of perovskite luminescent materials in the fields of LED lighting and information encryption, while shortening the time required for the preparation process of perovskite luminescent materials, reducing energy consumption, simplifying the operation steps, and enabling it to better meet the requirements of industrial production, is a technical problem that needs to be solved urgently. Summary of the Invention

[0005] One of the purposes of the present invention is to provide a double perovskite luminescent material that can be used for LED lighting and information encryption and has a tunable emission spectrum.

[0006] Another purpose of the present invention is to provide a preparation method of a double perovskite luminescent material that can be used for LED lighting and information encryption, has simple operation steps and short reaction time.

[0007] The technical solution adopted by the present invention to achieve the first purpose is: to provide a double perovskite luminescent material that can be used for LED lighting and information encryption; the chemical formula of the double perovskite luminescent material is: [Rb 1-x (NH4) x 2SnCl6: yBi 3+ ; wherein, x is the molar fraction of NH4 + , 0 < x < 1; y is the molar fraction of Bi 3+ , and ≤ 1.

[0008] The double perovskite luminescent material provided by the present invention has two emission peaks and can emit blue light or yellow light under ultraviolet light excitation in different wavelength ranges. Specifically, when excited by ultraviolet light with a wavelength of 320-370 nm, the double perovskite luminescent material emits blue light; when excited by ultraviolet light with a wavelength of 380-430 nm, the double perovskite luminescent material emits yellow light.

[0009] In some preferred embodiments, the double perovskite luminescent material is excited by ultraviolet light with a wavelength of 350 nm, and the wavelength range of the light emitted by the double perovskite luminescent material is 420-530 nm, the main emission wavelength is 460 nm, and the color coordinates are (x = 0.175, y = 0.170).

[0010] In some preferred embodiments, the double perovskite luminescent material is excited by ultraviolet light with a wavelength of 390 nm, and the wavelength range of the light emitted by the double perovskite luminescent material is 520-630 nm, the main emission wavelength is 560 nm, and the color coordinates are (x = 0.389, y = 0.413). [[ID=Z]]

[0011] Furthermore, by adjusting the values of x and y in the above chemical formula and the proportion of doped ions, the tuning of the emission light intensity under different excitation conditions can be achieved.

[0012] Preferably, 0.1 ≤ x ≤ 0.8, 0.0 Z ≤ y ≤ 0.2. Under this condition, when excited by ultraviolet light with a wavelength of 320-370 nm, the blue light emitted by the double perovskite luminescent material has a relatively high intensity. More preferably, 0.1 ≤ x ≤ 0.8, 0.02 ≤ y ≤ 0.1.

[0013] The technical solution adopted to achieve the second object of the present invention is: to provide a preparation method of a double perovskite luminescent material that can be used for LED lighting and information encryption, including the following steps:

[0014] S1. Prepare raw materials according to the molar ratio of each element in [Rb 1-x (NH4) x 2SnCl6: yBi 3+ ; where x is the molar fraction of NH4 + , 0 < x < 1; y is the molar fraction of Bi 3+ , 0 < y ≤ 1;

[0015] S2. Add the rubidium source and inorganic ammonium to the hydrochloric acid solution, mix well and heat to clarity to obtain the first product;

[0016] S3. Add the tin source and bismuth source to the hydrochloric acid solution, mix well and heat to clarity to obtain the second product;

[0017] S4. Under stirring conditions, the second product is added to the first product and reacted under certain temperature conditions. After centrifugation, the solid and liquid are separated. The solid product is dried and ground to obtain a double perovskite luminescent material that can be used for LED lighting and information encryption.

[0018] Further, in step S2, the rubidium source is selected from one or more combinations of rubidium oxides, carbonates, or chlorides; the inorganic ammonium is selected from ammonium chloride and / or ammonium bifluoride. Preferably, the rubidium source is rubidium chloride, and the inorganic ammonium is ammonium chloride.

[0019] Further, in step S3, the tin source is selected from tin tetrachloride; the bismuth source is selected from bismuth chloride and / or bismuth oxide.

[0020] Further, in steps S2 and S3, the mass fraction of the hydrochloric acid solution is 36%–38% (12 mol / L). The molar volume ratio of the tin source to the total amount of hydrochloric acid used in steps S2 and S3 is 1:(5–10) mol / L.

[0021] Preferably, in steps S2 and S3, the mixing is carried out under stirring conditions, with a stirring speed of 500–1500 rpm and a heating temperature of 75–85°C. These heating and stirring conditions can accelerate the dissolution rate of the raw materials and facilitate a rapid reaction.

[0022] Further, in step S4, the stirring speed is 500-1500 rpm, the reaction temperature is 75-85°C, and the reaction time is 5-20 min.

[0023] Preferably, in step S4, the centrifugation speed is 1000-5000 rpm, the drying temperature is 50-80°C, and the time is 8-24 h, in order to remove residual solvent from the product.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) The double perovskite luminescent material provided by this invention, applicable to LED lighting and information encryption, has two emission peaks and can emit blue or yellow light under ultraviolet light excitation in different wavelength ranges. It can be excited by ultraviolet light in the wavelength range of 320–370 nm, emitting light between 420–530 nm, and by ultraviolet light in the wavelength range of 380–430 nm, emitting light between 520–630 nm, exhibiting good tunability of the emission spectrum. Furthermore, by adjusting the proportion of different dopant ions in the chemical formula of the double perovskite luminescent material, the intensity of the emitted light can also be tuned. This double perovskite luminescent material is suitable for ultraviolet LED chip excitation and information encryption, and has broad prospects for promotion and application.

[0026] (2) The method for preparing a double perovskite luminescent material suitable for LED lighting and information encryption provided by the present invention employs a solution method to rapidly prepare [Rb] materials suitable for LED lighting and information encryption. 1-x (NH4) x ]2SnCl6:yBi 3+ Luminescent materials. This preparation method uses a rapid reaction in solution, which can control the total preparation time to 0.5 to 1 hour. Compared with the growth of single crystals, it saves a lot of time and energy, and can significantly reduce the cost of luminescent material preparation, making it suitable for mass production and application. Attached Figure Description

[0027] Figure 1 (a) is the [Rb] prepared according to the present invention. 0.9 (NH4) 0.1 ]2SnCl6:yBi 3+ (a) Emission spectrum of the luminescent material under ultraviolet light excitation at 350 nm wavelength; (b) [Rb] prepared in this invention. 0.9 (NH4) 0.1 ]2SnCl6:yBi 3+ (c) Excitation spectrum obtained by monitoring the luminescent material at a wavelength of 460 nm; 0.9 (NH4) 0.1 ]2SnCl6:yBi 3+ (d) Emission spectrum of the luminescent material under ultraviolet light excitation at 390 nm wavelength; 0.9 (NH4) 0.1 ]2SnCl6:yBi 3+ The excitation spectrum of the luminescent material was obtained by monitoring a wavelength of 560 nm (y = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0).

[0028] Figure 2 (a) is the [Rb] prepared according to the present invention. 0.8 (NH4) 0.2 ]2SnCl6:yBi 3+ (a) Emission spectrum of the luminescent material under ultraviolet light excitation at 350 nm wavelength; (b) [Rb] prepared in this invention. 0.8 (NH4) 0.2 ]2SnCl6:yBi 3+ (c) Excitation spectrum obtained by monitoring the luminescent material at a wavelength of 460 nm; 0.8 (NH4) 0.2 ]2SnCl6:yBi 3+(d) Emission spectrum of the luminescent material under ultraviolet light excitation at 390 nm wavelength; 0.8 (NH4) 0.2 ]2SnCl6:yBi 3+ The excitation spectrum of the luminescent material was obtained by monitoring a wavelength of 560 nm (y = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0).

[0029] Figure 3 (a) is the [Rb] prepared according to the present invention. 0.6 (NH4) 0.4 ]2SnCl6:yBi 3+ (a) Emission spectrum of the luminescent material under ultraviolet light excitation at 350 nm wavelength; (b) [Rb] prepared in this invention. 0.6 (NH4) 0.4 ]2SnCl6:yBi 3+ (c) Excitation spectrum obtained by monitoring the luminescent material at a wavelength of 460 nm; 0.6 (NH4) 0.4 ]2SnCl6:yBi 3+ (d) Emission spectrum of the luminescent material under ultraviolet light excitation at 390 nm wavelength; 0.6 (NH4) 0.4 ]2SnCl6:yBi 3+ The excitation spectrum of the luminescent material was obtained by monitoring a wavelength of 560 nm (y = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0).

[0030] Figure 4 (a) is the [Rb] prepared according to the present invention. 0.4 (NH4) 0.6 ]2SnCl6:yBi 3+ (a) Emission spectrum of the luminescent material under ultraviolet light excitation at 350 nm wavelength; (b) [Rb] prepared in this invention. 0.4 (NH4) 0.6 ]2SnCl6:yBi 3+ (c) Excitation spectrum obtained by monitoring the luminescent material at a wavelength of 460 nm; 0.4 (NH4) 0.6 ]2SnCl6:yBi 3+ (d) Emission spectrum of the luminescent material under ultraviolet light excitation at 390 nm wavelength; 0.4 (NH4) 0.6 ]2SnCl6:yBi 3+The excitation spectrum obtained by monitoring the luminescent material at a wavelength of 560 nm (y = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0).

[0031] Figure 5 .(a) The emission spectrum of the [Rb 0.2 (NH4) 0.8 2SnCl6:yBi 3+ luminescent material prepared by the present invention under ultraviolet light excitation at a wavelength of 350 nm; (b) The excitation spectrum obtained by monitoring the [Rb 0.2 (NH4)[[ID=1:3]] 0.8 2SnCl6:yBi 3+ luminescent material at a wavelength of 46 nm; (c) The emission spectrum of the [Rb 0.2 (NH4) 0.8 2SnCl6:yBi 3+ luminescent material prepared by the present invention under ultraviolet light excitation at a wavelength of 390 nm; (d) The excitation spectrum obtained by monitoring the [Rb 0.2 (NH4) 0.8 2SnCl6:yBi 3+ luminescent material at a wavelength of 560 nm (y = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0). Detailed implementation manners

[0032] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0033] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0034] The present invention provides a preparation method of a double perovskite luminescent material that can be used for LED lighting and information encryption, including the following steps:

[0035] Step 1: Prepare raw materials according to the molar ratio of each element in [Rb 1-x (NH4) x 2SnCl6:yBi 3+ ; where x is the molar fraction of NH4 + , 0 < x < 1; y is the molar fraction of Bi 3+ , 0 < y ≤ 1;

[0036] Step 2: Add the rubidium source and inorganic ammonium to a 12 mol / L hydrochloric acid solution, and mix until clear under the conditions of stirring speed of 800-3000 rpm and heating temperature of 75-85℃ to obtain the first product; wherein, the rubidium source is selected from one or more combinations of rubidium oxides, carbonates or chlorides; the inorganic ammonium is selected from ammonium chloride and / or ammonium bifluoride;

[0037] Step 3: Add the tin source and bismuth source to a 12 mol / L hydrochloric acid solution, and control the molar volume ratio of the tin source to the total amount of hydrochloric acid solution used in steps 2 and 3 to be 1:(5-10) mol / L. Mix until clear under the conditions of stirring speed of 500-1500 rpm and heating temperature of 75-85℃ to obtain the second product; wherein, the tin source is selected from tin tetrachloride, and the bismuth source is selected from bismuth chloride and / or bismuth oxide.

[0038] Step 4: Under stirring, add the second product to the first product and react at 75-85℃ for 5-20 minutes. Centrifuge to separate the solid and liquid products at 1000-5000 rpm. Dry the solid product at 50-80℃ for 8-24 hours to remove residual solvent. Then grind the product to obtain a double perovskite luminescent material that can be used for LED lighting and information encryption.

[0039] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0040] Example 1

[0041] [Rb 0.9 (NH4) 0.1 ]2SnCl6:0.1Bi 3+ Preparation of phosphors.

[0042] The preparation method is as follows: Weigh 1.8 mmol of rubidium chloride (RbCl) and 0.2 mmol of ammonium hydrogen fluoride (NH4HF2) into a 10 ml centrifuge tube containing 5 ml of hydrochloric acid (concentration 12 mol / L). Stir at 1000 rpm and heat at 80°C until the solution becomes clear to obtain the first product. Weigh 1 mmol of tin tetrachloride (SnCl4) and 0.1 mmol of bismuth chloride (BiCl3) into a 10 ml centrifuge tube containing 5 ml of hydrochloric acid (concentration 12 mol / L). Stir at 1000 rpm and heat at 80°C until the solution becomes clear to obtain the second product. Add the second product to the first product, stir vigorously, and heat for 10 min. After cooling, centrifuge to remove the supernatant. Place the centrifuge tube and the precipitate together in an oven and dry at 80°C for 12 h. Grind the dried material to obtain the target luminescent material.

[0043] Example 2

[0044] [Rb 0.9 (NH4) 0.1 ]2SnCl6:0.6Bi 3+ Preparation of phosphors.

[0045] The preparation method is as follows: Weigh 1.8 mmol of rubidium chloride (RbCl) and 0.2 mmol of ammonium hydrogen fluoride (NH4HF2) into a 10 ml centrifuge tube containing 5 ml of hydrochloric acid (concentration 12 mol / L). Stir at 1000 rpm and heat at 80°C until the solution becomes clear to obtain the first product. Weigh 1 mmol of tin tetrachloride (SnCl4) and 0.6 mmol of bismuth chloride (BiCl3) into a 10 ml centrifuge tube containing 5 ml of hydrochloric acid (concentration 12 mol / L). Stir at 1000 rpm and heat at 80°C until the solution becomes clear to obtain the second product. Add the second product to the first product, stir vigorously, and heat for 10 min. After cooling, centrifuge to remove the supernatant. Place the centrifuge tube and the precipitate together in an oven and dry at 80°C for 12 h. Grind the dried material to obtain the target luminescent material.

[0046] Example 3

[0047] [Rb 0.9 (NH4) 0.1 ]2SnCl6:1.0Bi 3+ Preparation of phosphors.

[0048] The preparation method is as follows: Weigh 1.8 mmol of rubidium chloride (RbCl) and 0.2 mmol of ammonium hydrogen fluoride (NH4HF2) into a 10 ml centrifuge tube containing 5 ml of hydrochloric acid (concentration 12 mol / L). Stir at 1000 rpm and heat at 80°C until the solution becomes clear to obtain the first product. Weigh 1 mmol of tin tetrachloride (SnCl4) and 1.0 mmol of bismuth chloride (BiCl3) into a 10 ml centrifuge tube containing 5 ml of hydrochloric acid (concentration 12 mol / L). Stir at 1000 rpm and heat at 80°C until the solution becomes clear to obtain the second product. Add the second product to the first product, stir vigorously, and heat for 10 min. After cooling, centrifuge to remove the supernatant. Place the centrifuge tube and the precipitate together in an oven and dry at 80°C for 12 h. Grind the dried material to obtain the target luminescent material.

[0049] Example 4

[0050] [Rb 0.9 (NH4) 0.1 ]2SnCl6:0.6Bi 3+ Preparation of phosphors.

[0051] The preparation method is as follows:

[0052] Weigh 1.8 mmol of rubidium chloride (RbCl) and 0.2 mmol of ammonium chloride (NH4Cl) into a 10 ml centrifuge tube containing 5 ml of hydrochloric acid (12 mol / L). Stir at 1000 rpm and heat at 80°C until the solution becomes clear to obtain the first product. Weigh 1 mmol of tin tetrachloride (SnCl4) and 0.6 mmol of bismuth chloride (BiCl3) into a 10 ml centrifuge tube containing 5 ml of hydrochloric acid (12 mol / L). Stir at 1000 rpm and heat at 80°C until the solution becomes clear to obtain the second product. Add the second product to the first product, stir vigorously, and heat for 10 min. After cooling, centrifuge to remove the supernatant. Place the centrifuge tube and precipitate together in an oven and dry at 50°C for 24 h. Grind the dried material to obtain the target luminescent material.

[0053] Example 5:

[0054] [Rb 0.6 (NH4) 0.4 ]2SnCl6:0.6Bi 3+ Preparation of phosphors.

[0055] The preparation method is as follows:

[0056] Weigh 1.2 mmol of rubidium chloride (RbCl) and 0.8 mmol of ammonium hydrogen fluoride (NH4HF2) into a 10 ml centrifuge tube containing 5 ml of hydrochloric acid (12 mol / L). Stir at 1000 rpm and heat at 80°C until the solution becomes clear to obtain the first product. Weigh 1 mmol of tin tetrachloride (SnCl4) and 0.3 mmol of bismuth carbonate (Bi2(CO3)3) into a 10 ml centrifuge tube containing 5 ml of hydrochloric acid (12 mol / L). Stir at 1000 rpm and heat at 80°C until the solution becomes clear to obtain the second product. Add the second product to the first product, stir vigorously, and heat for 10 min. After cooling, centrifuge to remove the supernatant. Place the centrifuge tube and precipitate together in an oven and dry at 80°C for 12 h. Grind the dried material to obtain the target luminescent material.

[0057] Example 6:

[0058] [Rb 0.4 (NH4) 0.6 ]2SnCl6:0.6Bi 3+ Preparation of phosphors.

[0059] The preparation method is as follows:

[0060] Weigh 0.8 mmol of rubidium chloride (RbCl) and 1.2 mmol of ammonium chloride (NH4Cl) into a 10 ml centrifuge tube containing 5 ml of hydrochloric acid (12 mol / L). Stir at 1000 rpm and heat at 80°C until the solution becomes clear to obtain the first product. Weigh 1 mmol of tin tetrachloride (SnCl4) and 0.3 mmol of bismuth trioxide (Bi2O3) into a 10 ml centrifuge tube containing 5 ml of hydrochloric acid (12 mol / L). Stir at 1000 rpm and heat at 80°C until the solution becomes clear to obtain the second product. Add the second product to the first product, stir vigorously, and heat for 10 min. After cooling, centrifuge to remove the supernatant. Place the centrifuge tube and precipitate together in an oven and dry at 50°C for 24 h. Grind the dried material to obtain the target luminescent material.

[0061] Example 7:

[0062] [Rb 0.2 (NH4) 0.8 ]2SnCl8:0.6Bi 3+ Preparation of phosphors.

[0063] The preparation method is as follows:

[0064] Weigh 0.4 mmol of rubidium chloride (RbCl) and 1.6 mmol of ammonium hydrogen fluoride (NH4HF2) into a 10 ml centrifuge tube containing 5 ml of hydrochloric acid (12 mol / L). Stir at 1000 rpm and heat at 80°C until the solution becomes clear to obtain the first product. Weigh 1 mmol of tin tetrachloride (SnCl4) and 0.6 mmol of bismuth chloride (BiCl3) into a 10 ml centrifuge tube containing 5 ml of hydrochloric acid (12 mol / L). Stir at 1000 rpm and heat at 80°C until the solution becomes clear to obtain the second product. Add the second product to the first product, stir vigorously, and heat for 10 min. After cooling, centrifuge to remove the supernatant. Place the centrifuge tube and precipitate together in an oven and dry at 50°C for 24 h. Grind the dried material to obtain the target luminescent material.

[0065] Application examples

[0066] Figure 1-5 This invention demonstrates the preparation of a double perovskite luminescent material [Rb]. 1-x (NH4) x ]2SnCl6:yBi 3+ The luminescence under ultraviolet light excitation conditions of different wavelengths. Figure 1-5It can be seen that the luminescent material prepared in the embodiments of the present invention emits wavelengths between 420nm and 530nm under ultraviolet light excitation of 320-370nm, with a dominant emission wavelength of 460nm, and its chromaticity coordinates are measured as (x = 0.175, y = 0.170), which are located in the blue light region; under ultraviolet light excitation of 380-430nm, the emission wavelength is between 520nm and 630nm, with a dominant emission wavelength of 560nm, and its chromaticity coordinates are measured as (x = 0.389, y = 0.413), which are located in the yellow light region.

[0067] Furthermore, through comparison Figure 1-5 The luminescence intensity under different x and y values ​​shows that, for different x values, when y = 0.1, the emitted blue light has a high intensity; while the intensity of emitted yellow light is affected by both x and y values. Under different x values, the y value required to obtain high-intensity yellow light is also different. The yellow light obtained under the following conditions has a high intensity: x = 0.1 and y = 0.5; x = 0.2 and y = 0.7; x = 0.4 and y = 1.0; x = 0.6 and y = 0.8; x = 0.8 and y = 0.5.

[0068] In summary, the material prepared by the method provided by this invention can be excited by a wide range of ultraviolet light and has tunable spectral properties, making it a novel luminescent material suitable for ultraviolet-excited LED lighting and information encryption.

[0069] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. The application of a double perovskite luminescent material in LED lighting and information encryption, characterized in that, When excited by ultraviolet light with a wavelength of 320~370nm, the double perovskite luminescent material emits blue light; when excited by ultraviolet light with a wavelength of 380~430nm, the double perovskite luminescent material emits yellow light. The chemical formula of the double perovskite luminescent material is: [Rb 1-x (NH4) x 2SnCl6: yBi 3+ ; where x is the mole fraction of NH4 + , 0 < x < 1; y is the mole fraction of Bi 3+ , 0 < y < 1; The preparation method of the dual perovskite luminescent material includes the following steps: S1, according to [Rb] 1-x (NH4) x ]2SnCl6:yBi 3+ Prepare raw materials by determining the molar ratio of each element; S2. Add the rubidium source and inorganic ammonium to the hydrochloric acid solution, mix well and heat until clear to obtain the first product; S3. Add the tin source and bismuth source to the hydrochloric acid solution, mix well and heat until clear to obtain the second product; S4. Under stirring conditions, the second product is added to the first product and reacted under certain temperature conditions. After centrifugation, the solid and liquid are separated. The solid product is dried and ground to obtain a double perovskite luminescent material that can be used for LED lighting and information encryption.

2. The application according to claim 1, characterized in that, 0.1≤x≤0.8, 0.01≤y≤0.

2.

3. The application according to claim 2, characterized in that, 0.1≤x≤0.8, 0.02≤y≤0.

1.

4. The application according to claim 1, characterized in that, In step S2, the rubidium source is selected from one or more combinations of rubidium oxides, carbonates or chlorides; the inorganic ammonium is selected from ammonium chloride and / or ammonium bifluoride.

5. The application according to claim 1, characterized in that, In step S3, the tin source is selected from tin tetrachloride; the bismuth source is selected from bismuth chloride and / or bismuth oxide.

6. The application according to claim 1, characterized in that, In steps S2 and S3, the mass fraction of the hydrochloric acid solution is 36% to 38%.

7. The application according to claim 1, characterized in that, In step S4, the reaction temperature is 75~85℃ and the reaction time is 5~20min.

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