CN104944471A - Tungsten doped bronze powder having high infrared shielding property and synthesis method of doped tungsten bronze powder - Google Patents

Abstract

The invention discloses a synthetic method for preparing doped tungsten bronze powder with high infrared shielding performance by adopting a hydrothermal-thermal reduction method, and what is to be solved is how to improve the infrared shielding performance of single-phase tungsten bronze whose molecular formula is M _x WO ₃ The problem is that this method first synthesizes a molybdenum-containing tungstate compound by a hydrothermal method, and then obtains a molybdenum-doped tungsten bronze powder with a diameter of 10nm to 200nm by a hydrogen reduction method. The raw materials are tungstate, sulfate and molybdate, the doping element used is molybdenum, and the molar ratio of molybdenum/tungsten is 0.005-0.05.

Description

A doped tungsten bronze powder with high infrared shielding performance and its synthesis method

technical field

The invention relates to a tungsten bronze material, more particularly to a doped tungsten bronze powder with high infrared shielding performance and a synthesis method thereof.

Background technique

Tungsten bronze is a typical non-stoichiometric compound, its chemical formula can be written as M _x WO ₃ , M is usually an alkali metal, and the value of x is between 0 and 1. Tungsten bronze generally has metallic luster and special color. The variety of M and the change of x value can make it have the properties of conductor or semiconductor. In recent years, this compound with mixed valence tungsten ions has attracted the attention of some researchers as a new infrared shielding material.

For the infrared shielding performance of tungsten bronze, most of the research objects at this stage are mainly tungsten bronze with a single system of molecular formula M _x WO ₃ . With the deepening of research, tungsten bronze of various complex systems may gradually become the focus. Complex systems can be constructed by doping, or by preparing composite tungsten bronzes containing various M cations in the channels. Compared with single-system tungsten bronze, the complex system will bring about changes in the crystal structure and may produce more crystal defects. On the one hand, the defects will destroy the continuity of the particle surface and enhance the localization of the surface plasmon, and the surface plasmon resonance is one of the reasons for the infrared absorption of tungsten bronze. On the other hand, it is also possible to change the size and structure of the tungsten bronze channel from the inside, causing lattice distortion such as shear. The change of the pore structure may introduce more M cations, thereby increasing the free carrier concentration, and the free carrier concentration will affect the infrared shielding performance of tungsten bronze.

The hydrothermal reaction process refers to the general term for related chemical reactions in fluids such as water, aqueous solution or steam at a certain temperature and pressure. According to different reaction types, hydrothermal reaction can be divided into hydrothermal oxidation, hydrothermal reduction, hydrothermal precipitation, hydrothermal synthesis, hydrothermal hydrolysis, hydrothermal crystallization, etc.

Hydrogen reduction method is a method of reducing metal oxides with hydrogen at high temperature to produce metals. Compared with other methods (such as carbon reduction method, zinc reduction method, etc.), the product properties are easier to control and the purity is higher.

Contents of the invention

In order to improve the infrared shielding performance of the tungsten bronze whose molecular formula is M _x WO ₃ , the present invention adopts a hydrothermal-thermal reduction method to prepare doped tungsten bronze powder with a rod-like structure. The diameter of the doped tungsten bronze powder is 10nm-200nm, the doping element used is molybdenum, and the molar ratio of molybdenum/tungsten is 0.005-0.05. The prepared doped tungsten bronze powder includes sodium tungsten bronze powder and potassium tungsten bronze powder.

The present invention proposes a doped tungsten bronze powder with high infrared shielding performance and its synthesis method. The synthesis method includes two steps of hydrothermal reaction and hydrogen reduction reaction; it is characterized in that:

The first step: hydrothermal reaction

Step 11, preparing a mixed solution;

Weigh a certain amount of tungstate, sulfate and molybdate, dissolve in deionized water to obtain a mixed solution;

Dosage: The concentration of tungstate in the mixed solution is 0.05mol/L～0.2mol/L, and the concentration of sulfate is 0.05mol/L～0.5mol/L. Add molybdate according to molybdenum/tungsten molar ratio of 0.005～0.05;

Step 12, prepare molybdenum-containing tungstate compound;

First use 10vol.% dilute sulfuric acid to adjust the pH value of the mixed solution to 1.4-1.7, and then pour it into a stainless steel reaction kettle lined with polytetrafluoroethylene;

Then, put the reaction kettle into an electric drying oven and heat it at a rate of 2-5°C/min to a reaction temperature of 200°C-240°C. The temperature inside the reactor is 200°C-240°C and the pressure is 1-5MPa. , after reacting for 20h-40h, after the reactor is cooled, take out the precipitate;

Then wash the precipitate with deionized water and ethanol in sequence, and dry at 50°C to 80°C for 10h to 24h to obtain a molybdenum-containing tungstate compound;

Step 2: Molybdenum-doped tungsten bronze powder prepared by hydrogen reduction reaction

Put the molybdenum-containing compound into the tube furnace and heat it at a rate of 2-5°C/min to a reaction temperature of 450°C-550°C; during the heating process, nitrogen must be continuously fed;

When the reaction temperature reaches 450°C-550°C, continue to feed hydrogen, and carry out sufficient reduction for 0.5h-2h under the atmosphere condition of H ₂ /N ₂ , and the reaction is completed. At this time, it is still necessary to feed nitrogen to prevent oxidation of the product; After the furnace temperature was cooled to room temperature, the product was taken out to obtain molybdenum-doped tungsten bronze powder.

The present invention adopts the hydrothermal-thermal reduction method to prepare the doped tungsten bronze powder with a rod-like structure. The advantage lies in:

① The diameter of the prepared doped tungsten bronze powder with a rod-like structure is 10nm-200nm.

② The infrared shielding performance of the doped tungsten bronze powder with a rod-like structure is improved by 30% to 70%.

③During the hydrothermal-thermal reduction process, the high yield of doped tungsten bronze powder is beneficial by controlling the heating and cooling rate and the reduction reaction temperature.

④Compared with traditional gold nanoparticles, the cost of raw materials selected by the present invention is lower. In medical photothermal therapy, the doped tungsten bronze powder prepared by the invention can be used as a low-cost substitute product.

⑤Compared with traditional indium tin oxide, the cost of raw materials selected by the present invention is lower. In the application of insulating glass, the doped tungsten bronze powder prepared by the invention can be used as a low-cost substitute product.

Description of drawings

Fig. 1 is the XRD spectrogram of the molybdenum-containing sodium tungstate compound prepared in Example 1.

Fig. 2 is the SEM photo of the molybdenum-containing sodium tungstate compound obtained in Example 1.

Figure 3 is the XRD spectrum of the rod-shaped molybdenum-doped sodium tungsten bronze powder obtained in Example 1.

Fig. 4 is the SEM photograph of the rod-shaped molybdenum-doped sodium tungsten bronze powder obtained in Example 1.

Fig. 5 is the UV-vis-NIR absorption spectrum of the rod-shaped molybdenum-doped sodium tungsten bronze powder obtained in Example 1.

Fig. 6 is the FT-IR transmission spectrum of the rod-shaped molybdenum-doped sodium tungsten bronze powder obtained in Example 1.

Fig. 7 is the XRD spectrogram of the molybdenum-containing potassium tungstate compound prepared in Example 2.

Fig. 8 is the SEM photo of the molybdenum-containing potassium tungstate compound obtained in Example 2.

Fig. 9 is the XRD spectrum of the rod-shaped molybdenum-doped potassium tungsten bronze powder obtained in Example 2.

Fig. 10 is an SEM photo of the rod-shaped molybdenum-doped potassium tungsten bronze powder obtained in Example 2.

Fig. 11 is the UV-vis-NIR absorption spectrum of the rod-shaped molybdenum-doped potassium tungsten bronze powder obtained in Example 2.

Fig. 12 is the FT-IR transmission spectrum of the rod-shaped molybdenum-doped potassium tungsten bronze powder obtained in Example 2.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

The invention adopts a hydrothermal-thermal reduction method to prepare rod-shaped doped tungsten bronze powder with high infrared shielding performance, including the following preparation steps:

The first step: hydrothermal reaction

Step 11, preparing a mixed solution;

Weigh a certain amount of tungstate, sulfate and molybdate, dissolve in deionized water to obtain a mixed solution;

Dosage: The concentration of tungstate in the mixed solution is 0.05mol/L～0.2mol/L, the concentration of sulfate is 0.05mol/L～0.5mol/L; add molybdate according to the molar ratio of molybdenum/tungsten of 0.005～0.05;

Step 12, prepare molybdenum-containing tungstate compound;

First use 10vol.% dilute sulfuric acid to adjust the pH value of the mixed solution to 1.4-1.7, and then pour it into a stainless steel reaction kettle lined with polytetrafluoroethylene;

Then, put the reaction kettle into an electric drying oven and heat it to a reaction temperature of 200℃~240℃ at a heating rate of 2~5℃/min. The temperature inside the reaction kettle is 200℃~240℃ and the pressure is 1~5MPa. Next, after reacting for 20h-40h, after the reactor is cooled, take out the precipitate;

Then wash the precipitate with deionized water and ethanol in sequence, and dry at 50°C to 80°C for 10h to 24h to obtain a molybdenum-containing tungstate compound;

Step 2: Molybdenum-doped tungsten bronze powder prepared by hydrogen reduction reaction

Put the molybdenum-containing compound into the tube furnace, and heat it at a rate of 2-5°C/min to a reaction temperature of 450°C-550°C; during the heating process, nitrogen must be continuously fed to remove oxygen and water vapor in the furnace;

When the reaction temperature reaches 450°C-550°C, continue to feed hydrogen, and carry out sufficient reduction for 0.5h-2h under the atmosphere condition of H ₂ (5vol.%)/N ₂ . Prevent product oxidation. After the temperature in the furnace is cooled to room temperature, the product is taken out to obtain molybdenum-doped tungsten bronze powder.

In the hydrogen reduction process of the present invention, in order to make the reduction reaction sufficient, the valence of tungsten is closely related to the reaction temperature, and the reaction temperature must be strictly controlled to ensure that the product is tungsten bronze with mixed valence, and its structure conforms to its molecular formula M _x WO ₃ , 0<x<1.

In order to characterize the composition, morphology and infrared shielding performance of the doped tungsten bronze powder, the present invention adopts XRD, SEM, TEM, XPS, ICP, UV-vis-NIR, FT-IR and other means for analysis.

The rod-shaped doped tungsten bronze powder prepared by the method of the invention has simple preparation process, regular shape and uniform size of the product, and good infrared shielding performance. Before and after doping, the infrared shielding performance is significantly improved.

Example 1

The steps for preparing molybdenum-doped sodium tungsten bronze powder are:

The first step: hydrothermal reaction

Step 11, preparing a mixed solution;

Weigh 0.83g of sodium tungstate (mass percent purity of 99.99%), 0.36g of sodium sulfate (mass percent purity of 99.99%) and 0.003g of sodium molybdate (mass percent purity of 99.95%), dissolve in 25mL In ionized water, a mixed solution is obtained;

In the present invention, sodium tungstate is selected as the source of tungsten and sodium; sodium sulfate plays a role similar to that of a capping agent to help control the morphology of the product; sodium molybdate is used as a doping agent to provide a source of molybdenum.

Step 12, preparing molybdenum-containing sodium tungstate compound;

After adjusting the pH value of the mixed solution to 1.5 with 10vol.% dilute sulfuric acid, pour it into a stainless steel reactor with a polytetrafluoroethylene lining;

Then, put the reactor into an electric drying oven, heat it to 200°C at a heating rate of 5°C/min, and react for 30h under the pressure of the reactor at 1.6MPa; 30°C, take out the precipitate A;

In the present invention, under the condition of reaction temperature 200° C. and pressure 1.6 MPa, it is to make the reaction solution have higher reactivity.

Then, with deionized water centrifugal washing precipitate A 3 times, obtain precipitate B;

In the present invention, precipitate A is only cleaned with deionized water, instead of using traditional dehydrated alcohol after washing to clean again, because the selected raw materials do not contain organic matter, which reduces the washing process (multiple washings) Part of the product will be taken away), and the recovery rate of the product is improved.

Finally, the precipitate B was dried at 60°C for 24 hours to obtain a molybdenum-containing sodium tungstate compound. Referring to Figure 1, XRD phase analysis was performed on the prepared molybdenum-containing sodium tungstate compound, and the molecular formula was Na _0.17 WO _3.085 ·0.17H ₂ O. Referring to Fig. 2, the morphology analysis of the prepared molybdenum-containing sodium tungstate compound was carried out by SEM, and it was a rod-like structure with a diameter of 100-150 nm.

The second step: Molybdenum-doped sodium bronze powder prepared by hydrogen reduction reaction

Put the prepared molybdenum-containing sodium tungstate compound into a tube furnace, and heat it up to a reaction temperature of 500°C at a heating rate of 5°C/min. During the heating process, nitrogen must be continuously fed to remove oxygen and water vapor in the furnace. wait. When the reaction temperature is reached, continue to feed hydrogen, and carry out the reduction reaction for 1 h under the atmosphere condition of H ₂ (5vol.%)/N ₂ ;

Then, the temperature was lowered to 30° C. at a rate of 2° C./min to obtain a rod-shaped molybdenum-doped sodium tungsten bronze powder. Nitrogen gas still needs to be introduced during the cooling process to prevent oxidation of the product.

In the present invention, if the reduction reaction temperature is lower than 400°C, the reduction reaction will not be sufficient enough to completely form mixed valence sodium tungsten bronze. If the reduction reaction temperature is higher than 600°C, the product will be over-reduced to form tungsten suboxides (such as W ₁₈ O ₄₉ ). The products obtained under these two reduction reaction temperature conditions do not have good infrared shielding properties.

Fig. 3 is the XRD diffraction pattern of the product obtained in Example 1 (the instrument model used: Rigaku D/max 2200PC). As shown in the figure, it shows that the characteristic diffraction peaks of the product obtained in Example 1 all belong to sodium tungsten bronze. The molecular formula is Na _0.3 WO ₃ .

Figure 4 is a scanning electron microscope (SEM) photograph of the product obtained in Example 1 (the instrument model used: JSM-7500F). The figure shows that the product obtained in Example 1 has a rod-like morphology, regular shape, uniform size, and a diameter of 100 nm to 150 nm.

Fig. 5 is the UV-vis-NIR figure of the product obtained in Example 1 and the molybdenum-free product synthesized under the same conditions (the instrument model used: Shimadzu UV3600). In Figure 5, the solid line is undoped sodium tungsten bronze (sodium molybdate is not added to the raw material). The dotted line is doped sodium tungsten bronze. By comparison, it can be seen that the doped sodium tungsten bronze has a low absorption of visible light, but a high absorption of infrared light with a wavelength below 2300nm. After doping with molybdenum, the infrared shielding performance is significantly improved by about 20%.

Fig. 6 is the FT-IR figure (instrument model used: Bruker Tensor 27) of the product that embodiment 1 makes and the product that does not contain molybdenum synthesized under the same conditions. In Figure 6, the solid line is undoped sodium tungsten bronze (sodium molybdate is not added to the raw material). The dotted line is doped sodium tungsten bronze. Through comparison, it can be seen that the transmittance of the doped sodium tungsten bronze to infrared light with a wavelength of 2000nm to 5000nm is lower than that before doping, and the infrared shielding performance is improved by about 30%.

Example 2

The steps for preparing molybdenum-doped sodium tungsten bronze powder are:

The first step: hydrothermal reaction

Step 11, preparing a mixed solution;

Weigh 0.81g of sodium tungstate (mass percent purity of 99.99%), 0.35g of sodium sulfate (mass percent purity of 99.99%) and 0.006g of sodium molybdate (mass percent purity of 99.95%), dissolve in 25mL In ionized water, a mixed solution is obtained;

Step 12, preparing molybdenum-containing sodium tungstate compound;

After adjusting the pH value of the mixed solution to 1.7 with 10vol.% dilute sulfuric acid, pour it into a stainless steel reactor with a polytetrafluoroethylene lining;

Then, put the reactor into an electric drying oven, heat it to 200°C at a heating rate of 3°C/min, and react for 30h at a pressure of 1.6MPa in the reactor; 30°C, take out the precipitate A;

Then, with deionized water centrifugal washing precipitate A 3 times, obtain precipitate B;

Finally, dry the precipitate B at 80°C for 20 hours to obtain a molybdenum-containing sodium tungstate compound with a diameter of 100-150 nm.

The second step: Molybdenum-doped sodium bronze powder prepared by hydrogen reduction reaction

Put the prepared molybdenum-containing sodium tungstate compound into a tube furnace, and heat it up to a reaction temperature of 500°C at a heating rate of 5°C/min. During the heating process, nitrogen must be continuously fed to remove oxygen and water vapor in the furnace. wait. When the reaction temperature is reached, continue to feed hydrogen, and carry out the reduction reaction for 1 h under the atmosphere condition of H ₂ (5vol.%)/N ₂ ;

Then, the temperature was lowered to 30° C. at a rate of 5° C./min to obtain a rod-shaped molybdenum-doped sodium tungsten bronze powder. Nitrogen gas still needs to be introduced during the cooling process to prevent oxidation of the product.

The performance analysis of the molybdenum-doped sodium tungsten bronze powder obtained in Example 2 was carried out by XRD and SEM: the characteristic diffraction peaks of the product obtained in Example 2 belonged to sodium tungsten bronze through XRD analysis. Observation of the product obtained in Example 2 by SEM morphology has a rod-like morphology, regular shape, uniform size, and a diameter of 100 nm to 150 nm.

The product prepared in Example 2 has low absorption of visible light, but high absorption of infrared light with a wavelength below 2300nm. After doping with molybdenum, the infrared shielding performance is significantly improved, about 17%.

The transmittance of the product prepared in Example 2 to infrared light with a wavelength of 2000nm-5000nm is lower than that before doping, and the infrared shielding performance is improved by about 28%.

Example 3

The steps for preparing molybdenum-doped sodium tungsten bronze powder are:

The first step: hydrothermal reaction

Step 11, preparing a mixed solution;

Weigh 0.78g of sodium tungstate (mass percent purity of 99.99%), 0.32g of sodium sulfate (mass percent purity of 99.99%) and 0.03g of sodium molybdate (mass percent purity of 99.95%), dissolve in 25mL In ionized water, a mixed solution is obtained;

Step 12, preparing molybdenum-containing sodium tungstate compound;

After adjusting the pH value of the mixed solution to 1.5 with 10vol.% dilute sulfuric acid, pour it into a stainless steel reactor with a polytetrafluoroethylene lining;

Then, put the reactor into an electric drying oven, heat it to 240°C at a heating rate of 4°C/min, and react for 40h at a pressure of 1.6MPa in the reactor; 30°C, take out the precipitate A;

Then, with deionized water centrifugal washing precipitate A 3 times, obtain precipitate B;

Finally, dry the precipitate B at 60°C for 18 hours to obtain a molybdenum-containing sodium tungstate compound with a diameter of 100-150 nm.

The second step: Molybdenum-doped sodium bronze powder prepared by hydrogen reduction reaction

Put the prepared molybdenum-containing sodium tungstate compound into a tube furnace, and heat it to a reaction temperature of 450°C at a heating rate of 5°C/min. During the heating process, nitrogen must be continuously fed to remove oxygen and water vapor in the furnace. wait. When the reaction temperature is reached, continue to feed hydrogen, and carry out the reduction reaction for 1 h under the atmosphere condition of H ₂ (5vol.%)/N ₂ ;

Then, the temperature was lowered to 30° C. at a rate of 1° C./min to obtain a rod-shaped molybdenum-doped sodium tungsten bronze powder. Nitrogen gas still needs to be introduced during the cooling process to prevent oxidation of the product.

The performance analysis of the molybdenum-doped sodium tungsten bronze powder obtained in Example 3 was carried out by XRD and SEM: the characteristic diffraction peaks of the product obtained in Example 3 belonged to sodium tungsten bronze through XRD analysis. The product obtained in Example 3 has a rod-like appearance, regular shape, uniform size, and a diameter of 100 nm to 150 nm according to SEM morphology observation.

The product prepared in Example 3 has low absorption of visible light, but high absorption of infrared light with a wavelength below 2300nm. After doping with molybdenum, the infrared shielding performance is significantly improved, about 19%.

The transmittance of the product prepared in Example 3 to infrared light with a wavelength of 2000nm-5000nm is lower than that before doping, and the infrared shielding performance is improved by about 26%.

Example 4

The steps for preparing molybdenum-doped potassium tungsten bronze powder are:

The first step: hydrothermal reaction

Step 11, preparing a mixed solution;

Weigh 0.81g of potassium tungstate (mass percentage purity is 99.5%), 0.87g of potassium sulfate (mass percentage purity is 99.99%) and 0.008g of potassium molybdate (mass percentage purity is 99.9%), dissolve in 25mL In deionized water, a mixed solution was obtained.

Step 12, preparing molybdenum-containing potassium tungstate compound;

First use 10vol.% dilute sulfuric acid to adjust the pH value of the solution to 1.5, and then pour it into a stainless steel reactor with a polytetrafluoroethylene lining;

Then, put the reactor into an electric drying oven, heat it to 220°C at a heating rate of 3°C/min, and react for 20h at a pressure of 2.5MPa in the reactor; 30°C, take out the precipitate A;

Then, with deionized water centrifugal washing precipitate A 3 times, obtain precipitate B;

Finally, the precipitate B was dried at 60°C for 24 hours to obtain a molybdenum-containing potassium tungstate compound. Referring to Fig. 7, the obtained molybdenum-containing potassium tungstate compound was subjected to XRD phase analysis, and the molecular formula was K _0.33 WO _3.165 . Compared with the standard card, the intensity of the (002) diffraction peak is obviously increased, because the crystal grows preferentially along the (002) crystal plane. The intensity of the (400) diffraction peak decreased significantly, indicating that the potassium content in the resulting product was higher. Referring to Fig. 8, the prepared molybdenum-containing potassium tungstate compound was subjected to SEM morphology analysis, which was a rod-like structure with a diameter of 15-20nm.

The second step: Molybdenum-doped potassium bronze powder by hydrogen reduction reaction

Put the obtained molybdenum-containing potassium tungstate compound into a tube furnace, and heat it to a reaction temperature of 450°C at a heating rate of 3°C/min. During the heating process, nitrogen gas must be continuously fed to remove oxygen and water vapor in the furnace. wait. When the reaction temperature is reached, hydrogen gas is continuously introduced, and the reduction reaction is carried out for 1.5 h under the atmosphere condition of H ₂ (5vol.%)/N ₂ ;

Then, the temperature was lowered to 30° C. at a rate of 2° C./min to obtain a rod-shaped molybdenum-doped potassium tungsten bronze powder. Nitrogen gas still needs to be introduced during the cooling process to prevent oxidation of the product.

In the present invention, if the reduction reaction temperature is lower than 400° C., the reduction reaction will not be sufficient, and potassium tungsten bronze in mixed valence state cannot be completely formed. If the reduction reaction temperature is higher than 600°C, the product will be over-reduced to form tungsten suboxides (such as W ₁₈ O ₄₉ ). The products obtained under these two reduction reaction temperature conditions do not have good infrared shielding properties.

Fig. 9 is the XRD diffraction pattern of the product obtained in Example 2 (the instrument model used: Rigaku D/max 2200PC). Shown in the figure shows that the characteristic diffraction peaks of the product obtained in Example 2 all belong to potassium tungsten bronze. The molecular formula is K _0.33 WO ₃ .

Fig. 10 is a scanning electron microscope (SEM) photograph of the product obtained in Example 2 (the instrument model used: JSM-7500F). The figure shows that the product obtained in Example 2 has a rod-like morphology, regular shape, uniform size, and a diameter of 15 nm to 20 nm.

Fig. 11 is the UV-vis-NIR figure of the product prepared in Example 2 and the molybdenum-free product synthesized under the same conditions (the instrument model used: Shimadzu UV3600). In Fig. 11, the solid line is undoped potassium tungsten bronze (sodium molybdate is not added to the raw material). The dotted line is potassium-doped tungsten bronze. By comparison, it can be seen that the doped potassium tungsten bronze has a low absorption of visible light, but a high absorption of infrared light with a wavelength below 2300nm. After doping with molybdenum, the infrared absorption performance is significantly improved, about 15%.

Fig. 12 is the FT-IR figure (instrument model used: Bruker Tensor 27) of the product that embodiment 2 makes and the product that does not contain molybdenum synthesized under the same conditions. In Fig. 12, the solid line is undoped potassium tungsten bronze (sodium molybdate is not added to the raw material). The dotted line is potassium-doped tungsten bronze. Through comparison, it can be seen that the transmittance of the doped potassium tungsten bronze to infrared light with a wavelength of 2000nm to 5000nm is lower than that before doping, and the infrared shielding performance is improved by about 70%.

Example 5

The steps for preparing molybdenum-doped potassium tungsten bronze powder are:

The first step: hydrothermal reaction

Step 11, preparing a mixed solution;

Weigh 0.79g of potassium tungstate (mass percentage purity is 99.5%), 0.85g of potassium sulfate (mass percentage purity is 99.99%) and 0.025g of potassium molybdate (mass percentage purity is 99.9%), dissolve in 25mL In deionized water, a mixed solution was obtained.

Step 12, preparing molybdenum-containing potassium tungstate compound;

First use 10vol.% dilute sulfuric acid to adjust the pH value of the solution to 1.7, and then pour it into a stainless steel reaction kettle with a polytetrafluoroethylene lining;

Then, put the reactor into an electric drying oven, heat it to 200°C at a heating rate of 3°C/min, and react for 20h at a pressure of 2.5MPa in the reactor; 30°C, take out the precipitate A;

Then, with deionized water centrifugal washing precipitate A 3 times, obtain precipitate B;

Finally, dry the precipitate B at 80°C for 15 hours to obtain a molybdenum-containing potassium tungstate compound with a diameter of 15-20 nm.

The second step: Molybdenum-doped potassium bronze powder by hydrogen reduction reaction

Put the obtained molybdenum-containing potassium tungstate compound into a tube furnace, and heat it up to a reaction temperature of 500°C at a heating rate of 5°C/min. During the heating process, nitrogen must be continuously fed to remove oxygen and water vapor in the furnace. wait. When the reaction temperature is reached, hydrogen gas is continuously introduced, and the reduction reaction is carried out for 1.5 h under the atmosphere condition of H ₂ (5vol.%)/N ₂ ;

Then, the temperature was lowered to 30° C. at a rate of 1° C./min to obtain a rod-shaped molybdenum-doped potassium tungsten bronze powder. Nitrogen gas still needs to be introduced during the cooling process to prevent oxidation of the product.

The performance analysis of the molybdenum-doped potassium tungsten bronze powder obtained in Example 5 was carried out by XRD and SEM: the characteristic diffraction peaks of the product obtained in Example 5 belonged to potassium tungsten bronze through XRD analysis. The product obtained in Example 5 has a rod-like appearance, regular shape, uniform size, and a diameter of 15 nm to 20 nm, as observed by SEM morphology.

The product obtained in Example 5 has low absorption of visible light, but high absorption of infrared light with a wavelength below 2300nm. After doping with molybdenum, the infrared absorption performance is significantly improved, about 13%.

The transmittance of the product prepared in Example 5 to infrared light with a wavelength of 2000nm-5000nm is lower than that before doping, and the infrared shielding performance is improved by about 40%.

The present invention proposes a synthetic method for preparing doped tungsten bronze powder with high infrared shielding performance by using a hydrothermal-thermal reduction method. The technical problem to be solved is how to improve the infrared shielding performance of tungsten bronze whose molecular formula is M _x WO ₃ . In the method, a molybdenum-containing compound is firstly synthesized by a hydrothermal method, and then a molybdenum-doped tungsten bronze powder is obtained by a hydrogen reduction method, thereby obtaining a molybdenum-doped tungsten bronze powder with a diameter of 10nm to 200nm. The raw materials are tungstate, sulfate and molybdate, the doping element used is molybdenum, and the molar ratio of molybdenum/tungsten is 0.005-0.05.

Claims (9)

1. there is a Doped Tungsten bronze powder for high IR shielding properties, it is characterized in that: described Doped Tungsten bronze powder is sodium tungsten bronze powder or potassium tungsten bronze(s) powder.

2. a kind of Doped Tungsten bronze powder with high IR shielding properties according to claim 1, is characterized in that: the composition of described sodium tungsten bronze powder is Na _0.3wO ₃.

3. a kind of Doped Tungsten bronze powder with high IR shielding properties according to claim 1, is characterized in that: the composition of described potassium tungsten bronze(s) powder is K _0.33wO ₃.

4. have Doped Tungsten bronze powder and the synthetic method thereof of high IR shielding properties, described synthetic method includes hydro-thermal reaction and hydrogen reduction reaction two step; It is characterized in that:

The first step: hydro-thermal reaction

Step 11, prepares mixing solutions;

Take a certain amount of tungstate, vitriol and molybdate, be dissolved in deionized water, obtain mixing solutions;

Consumption: in mixing solutions, tungstate concentration is 0.05mol/L ~ 0.2mol/L, sulfate concentration is 0.05mol/L ~ 0.5mol/L.Molybdenum by 0.005 ~ 0.05/tungsten mol ratio adds molybdate;

Step 12, preparation is containing the tungstate compound of molybdenum;

After first regulating pH value to 1.4 ~ 1.7 of mixing solutions with the dilute sulphuric acid of 10vol.%, pour into and have in teflon-lined stainless steel cauldron;

Then, reactor is put into electrically heated drying cabinet, be heated to temperature of reaction 200 DEG C ~ 240 DEG C with the speed of 2 ~ 5 DEG C/min, reactor temperature in the kettle is 200 DEG C ~ 240 DEG C, pressure is under 1 ~ 5MPa condition, after reaction 20h ~ 40h, after the cooling of question response still, take out throw out;

Then use deionized water and ethanol washing and precipitating thing successively, and at 50 DEG C ~ 80 DEG C dry 10h ~ 24h, obtain the tungstate compound containing molybdenum;

Second step: the tungsten bronze(s) powder of hydrogen reducing reaction molybdenum doping processed

Compound containing molybdenum is put into tube furnace, is heated to temperature of reaction 450 DEG C ~ 550 DEG C with the temperature rise rate of 2 ~ 5 DEG C/min; Need in heat-processed to continue to pass into nitrogen;

When reaching temperature of reaction 450 DEG C ~ 550 DEG C, continue to pass into hydrogen, at H ₂/ N ₂atmospheric condition under fully reduce 0.5h ~ 2h, reaction terminates, and now still needs to pass into nitrogen, prevents product to be oxidized; Be cooled to after room temperature until in-furnace temperature, take out product, obtain the tungsten bronze(s) powder of molybdenum doping.

5. a kind of Doped Tungsten bronze powder and synthetic method thereof with high IR shielding properties according to claim 4, it is characterized in that: in step 12, the cooling temperature speed adopted in the process of cooling of described reactor is 0.3 ~ 2 DEG C/min.

6. a kind of Doped Tungsten bronze powder and synthetic method thereof with high IR shielding properties according to claim 4, it is characterized in that: in second step, the cooling temperature speed adopted in the process of cooling of described tube furnace is 0.3 ~ 2 DEG C/min.

7. a kind of Doped Tungsten bronze powder and synthetic method thereof with high IR shielding properties according to claim 4, is characterized in that: the diameter of obtained Doped Tungsten bronze powder is 10nm ~ 200nm.

8. a kind of Doped Tungsten bronze powder and synthetic method thereof with high IR shielding properties according to claim 4, is characterized in that: the infrared shielding performance of obtained Doped Tungsten bronze powder improves 30% ~ 70%.

9. according to claim 4 a kind of there is high IR shielding properties Doped Tungsten bronze powder and synthetic method, it is characterized in that: hydrothermal method being combined with hot reducing method, can to improve molecular formula be M _xwO ₃tungsten bronze(s) infrared shielding performance.