Preparation method and application of uniformly-coated special-shaped core-shell structure applied to infrared band
By preparing a uniform core-shell structure on the irregular structure, the problem of uniform coverage of the VO2 shell protection outside the irregular morphology is solved, and efficient thermal regulation and anti-aging performance in the infrared band are achieved, which is suitable for building and car window glass.
Patent Information
- Application Number
- CN202510862846.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-25
- Publication Date
- 2025-09-23
AI Technical Summary
In the existing technology, the shell protection of VO2 is mainly carried out around spherical particles, and it is difficult to achieve uniform core-shell coating outside the irregular morphology and there are problems in the study of its infrared performance.
A special-shaped structure is used as the core, and a core-shell structure is prepared through ultrasonic dispersion, stirring and mixing steps at room temperature. A material with anti-aging properties is used as the shell layer, combined with an improved process to form a uniform coating structure.
The special-shaped core-shell structure achieves efficient thermal regulation in the infrared band, provides anti-aging performance, is suitable for building and car window glass, and extends service life.
Smart Images
Figure CN120682791A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a preparation method of a special-shaped core-shell structure and application thereof. Background Art
[0002] The space environment in which spacecraft in orbit are extremely harsh, subject to high-temperature solar radiation and the radiation of deep space. These dramatic temperature fluctuations pose significant challenges to thermal control systems. With the increasing variability of heat flux outside the spacecraft, the rapid increase in the power density of internal equipment dissipation, and the further improvement of temperature control precision, higher requirements are being placed on thermal control technologies based on radiative heat exchange surfaces. Traditional thermal control coatings, due to their fixed thermal radiation properties, cannot adjust their own thermal radiation characteristics based on changes in internal and external heat fluxes, making it impossible to achieve adaptive control of equipment temperature. However, the infrared radiation characteristics of variable emissivity intelligent thermal control coatings can dynamically change according to the operating temperature, thereby achieving temperature control effects of low-temperature insulation and high-temperature heat dissipation, significantly improving thermal control efficiency and becoming a critical component of spacecraft thermal control systems. VO2 is a typical thermochromic material. It exhibits high infrared transmittance in a semiconductor state at low temperatures and high infrared reflectance in a metallic state at high temperatures. Leveraging these properties, VO2 can be coated onto protected structures or devices. At high temperatures, it effectively dissipates heat, lowering the temperature of the protected object and reducing internal cooling energy consumption. At low temperatures, it effectively insulates the object, maintaining its temperature and reducing heating energy consumption, thereby achieving energy savings. However, its practical application still faces numerous challenges. Most notably, VO2's poor antioxidant capacity and weather resistance significantly limit its practical applications. Common approaches address this issue by surface modification or coating VO2 nanoparticles with a highly infrared-transmitting shell. Current literature on VO2 shell protection primarily focuses on spherical particles, but the ability to achieve uniform core-shell coatings on even irregularly shaped particles and the associated infrared performance remain challenges. Summary of the Invention
[0003] The present invention aims to solve the problem that the existing shell protection is mainly carried out around spherical particles, and there are still problems in how to perform uniform core-shell coating on irregular morphologies and its infrared performance research, and further provide a preparation method and application of uniformly coated irregular core-shell structures for use in the infrared band.
[0004] A method for preparing a uniformly coated heteromorphic core-shell structure for use in the infrared band is carried out according to the following steps:
[0005] 1. Ultrasonic dispersion of the heteromorphic cores in deionized water, and then adding a surfactant and stirring at room temperature to obtain a core precursor solution;
[0006] 2. Add the shell precursor to deionized water under stirring at room temperature to obtain a shell precursor solution / suspension;
[0007] 3. Mixing and dispersing the core precursor solution and the shell precursor solution / suspension at room temperature with stirring to obtain a mixture;
[0008] Fourth, the mixture is reacted, and then centrifugally washed, dried and ground to obtain a uniformly coated heteromorphic core-shell structure suitable for use in the infrared band.
[0009] The invention discloses an application of a uniformly coated heteromorphic core-shell structure in the infrared band, which is used for infrared band regulation.
[0010] The beneficial effects of the present invention are:
[0011] The present invention uses a shaped structure with a larger scattering cross-section as the functional phase. Compared to the commonly used spherical structure, the shaped structure has a larger scattering cross-section and greater theoretical infrared control capability. Therefore, by adjusting the distribution of the functional phase in the coating and controlling the overlapping structure of the functional phase in the coating, it is possible to switch between positive and negative differential emissivity performance. However, compared to the common spherical structure, the preparation of a shaped uniform core-shell structure is more difficult.
[0012] The present invention selects a material with anti-aging properties as the shell material and a special-shaped structure as the core, taking advantage of its large scattering cross-section to form a larger surface area of the shell. Combined with process improvements, a clear core-shell structure is achieved. The prepared uniformly coated special-shaped core-shell structure for use in the infrared band has a low-temperature emissivity of 0.26-0.31 at 0°C and a high-temperature emissivity of 0.44-0.71 at 70°C in the 8μm-14μm band. The emissivity test from 0°C to 70°C shows an emissivity change of 0.15-0.40. Under the conditions of a damp heat aging accelerated test at a temperature of 60°C and a humidity of 90%, after 30 days in the 8μm-14μm band, the low-temperature emissivity at 0°C is 0.28-0.30, the high-temperature emissivity at 70°C is 0.46-0.69, and the emissivity test from 0°C to 70°C shows an emissivity change of 0.16-0.39.
[0013] The method of the present invention has a short process, low energy consumption, large thermal control capability, loose preparation conditions, and is easy for large-scale production. It is suitable for building window glass and vehicle window glass, provides anti-aging performance, and extends service life. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1TEM comparison images of powders: (a) rod-shaped VO2 micro-nano powder described in step 1 of Example 1, (b) overall morphology of the heteromorphic core-shell structure VO2(M)@HfO2 powder prepared in Example 1, (c) high-magnification morphology of the heteromorphic core-shell structure VO2(M)@HfO2 powder prepared in Example 1;
[0015] Figure 2 Optical images of powders corroded in a strong acid (pH = 0) environment for 10 min, 20 min, and 30 min, respectively: (a) HfO2 powder, (b) rod-shaped VO2 micro-nano powder described in step 1 of Example 3, (c) heteromorphic core-shell structure VO2(M)@HfO2 powder prepared in Example 3, (d) heteromorphic core-shell structure VO2(M)@HfO2 powder prepared in a comparative experiment;
[0016] Figure 3 XRD patterns of the heteromorphic core-shell structured VO2(M)@HfO2 powders prepared in Examples 1 to 3;
[0017] Figure 4 Fourier transform infrared spectra of the heteromorphic core-shell structure VO2(M)@HfO2 powder prepared in Example 2 at low and high temperatures. DETAILED DESCRIPTION
[0018] Specific embodiment 1: This embodiment is a method for preparing a uniformly coated heteromorphic core-shell structure for use in the infrared band, which is carried out in the following steps:
[0019] 1. Ultrasonic dispersion of the heteromorphic core in deionized water, then adding a surfactant and stirring at room temperature to obtain a core precursor solution;
[0020] 2. Add the shell precursor to deionized water under stirring at room temperature to obtain a shell precursor solution / suspension;
[0021] 3. Mixing and dispersing the core precursor solution and the shell precursor solution / suspension at room temperature with stirring to obtain a mixture;
[0022] Fourth, the mixture is reacted, and then centrifugally washed, dried and ground to obtain a uniformly coated heteromorphic core-shell structure suitable for use in the infrared band.
[0023] This embodiment can generate a shell layer of uniform thickness on the surface of the special-shaped structure, and has little effect on the infrared control performance of the core material.
[0024] The beneficial effects of this embodiment are:
[0025] This embodiment uses a shaped structure with a larger scattering cross-section as the functional phase. Compared to the commonly used spherical structure, the shaped structure has a larger scattering cross-section and greater theoretical infrared control capability. Therefore, by adjusting the distribution of the functional phase in the coating and controlling the overlapping structure of the functional phase in the coating, it is possible to achieve switching between positive and negative differential emissivity performance. However, compared to the common spherical structure, the preparation of a uniform shaped core-shell structure is more difficult.
[0026] This embodiment uses a material with anti-aging properties as the shell material and a special-shaped structure as the core. Taking advantage of its large scattering cross-section, the shell has a larger surface area. Combined with process improvements, a distinct core-shell structure is achieved. The prepared uniformly coated special-shaped core-shell structure for infrared applications has a low-temperature emissivity of 0.26-0.31 at 0°C and a high-temperature emissivity of 0.44-0.71 at 70°C in the 8μm-14μm band. Emissivity tests from 0°C to 70°C show an emissivity change of 0.15-0.40. Under accelerated heat aging test conditions at 60°C and 90% humidity, after 30 days in the 8μm-14μm band, the low-temperature emissivity at 0°C is 0.28-0.30, the high-temperature emissivity at 70°C is 0.46-0.69, and the emissivity change from 0°C to 70°C is 0.16-0.39.
[0027] The method of this embodiment has a short process, low energy consumption, large thermal control capability, loose preparation conditions, and is easy to mass-produce. It is suitable for building window glass and vehicle window glass, provides anti-aging performance, and extends service life.
[0028] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the mass ratio of the heteromorphic core described in step 1 to the volume of deionized water is 1 g: (62.5-125) mL; the mass ratio of the heteromorphic core described in step 1 to the surfactant described in step 1 is (3.2-12.8):1; and the surfactant described in step 1 is polyvinylpyrrolidone-K30, CTAB, polyvinylpyrrolidone-K60, or sorbitan fatty acid ester. Other aspects are the same as specific embodiment 1.
[0029] Specific embodiment 3: This embodiment differs from either specific embodiment 1 or 2 in that, in step 1, the irregular cores are ultrasonically dispersed in deionized water at a power of 40 W to 150 W for 30 to 120 minutes. A surfactant is then added and stirred for 30 to 120 minutes at room temperature and a stirring speed of 400 to 1500 rpm to obtain a core precursor solution. Other steps are the same as those of specific embodiment 1 or 2.
[0030] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the special-shaped core described in step 1 is a rod-shaped VO2 micro-nano powder, which is specifically prepared according to the following steps:
[0031] Vanadium pentoxide powder and oxalic acid dihydrate powder are sequentially added to deionized water, and mixed for 8 h to 12 h at room temperature and a stirring speed of 400 r / min to 1500 r / min to obtain a mixture. The mixture is hydrothermally reacted at a temperature of 200°C to 240°C for 1 h to 6 h. After cooling to room temperature, the mixture is alternately centrifuged and washed 3 to 5 times with deionized water and ethanol, and then dried at a temperature of 60°C to 80°C for 8 h to 12 h. After grinding, a dark black powder, namely VO2(B), is obtained. The dark black powder is heat-treated for 10 min to 2 h at an argon flow rate of 100 sccm to 400 sccm and a temperature of 500°C to 600°C, and finally cooled to room temperature to obtain rod-shaped VO2 micro-nano powder, namely VO2(M).
[0032] The mass ratio of the vanadium pentoxide powder to the oxalic acid dihydrate powder is 1:(2-5); the volume ratio of the vanadium pentoxide powder to deionized water is 1 g:(40-50) mL. Other aspects are the same as those of the first to third embodiments.
[0033] Specific Embodiment 5: This embodiment differs from Specific Embodiments 1 to 4 in that the volume ratio of the shell precursor mass to deionized water in step 2 is 1 g: (5-10) mL; and the shell precursor in step 2 is hafnium tetrachloride, TEOS, or calcium chloride. Other aspects are the same as Specific Embodiments 1 to 5.
[0034] Specific embodiment 6: This embodiment differs from Specific embodiments 1 to 5 in that in step 2, the shell precursor is added to deionized water and stirred and dispersed for 1 to 12 hours at room temperature and a stirring speed of 400 to 1500 r / min. Other aspects are the same as Specific embodiments 1 to 5.
[0035] Specific embodiment 7: This embodiment differs from Specific embodiments 1 to 6 in that the mass ratio of the heteromorphic cores in the core precursor solution in step 3 to the shell precursor in step 2 is (1-5):1; and in step 3, the core precursor solution and the shell precursor solution / suspension are mixed and dispersed at room temperature and a stirring speed of 400-1200 rpm for 6-24 hours. Other aspects are the same as Specific embodiments 1 to 6.
[0036] Specific embodiment 8: This embodiment differs from Specific embodiments 1 to 7 in that: the reaction in step 4 is hydrothermally carried out at a temperature of 100°C to 160°C for 12 to 24 hours; the centrifugal washing in step 4 is performed by alternating centrifugal washing with deionized water and ethanol three to five times; and the drying in step 4 is performed at a temperature of 60°C to 80°C for 8 to 24 hours. Other aspects are the same as Specific embodiments 1 to 7.
[0037] Specific embodiment 9: This embodiment differs from any one of specific embodiments 1 to 8 in that the shell layer of the uniformly coated heteromorphic core-shell structure for infrared applications prepared in step 4 is made of hafnium oxide, silicon oxide, or calcium fluoride, and has a thickness of 5 nm to 50 nm. Other aspects are the same as specific embodiments 1 to 8.
[0038] Specific embodiment ten: This embodiment is an application of a uniformly coated heteromorphic core-shell structure in the infrared band, which is used for infrared band regulation.
[0039] The following examples are used to verify the beneficial effects of the present invention:
[0040] Example 1:
[0041] A method for preparing a uniformly coated heteromorphic core-shell structure for use in the infrared band is carried out according to the following steps:
[0042] First, the rod-shaped VO2 nanopowder was ultrasonically dispersed in deionized water at a power of 100 W for 30 minutes. Then, polyvinylpyrrolidone-K30 was added and stirred for 60 minutes at room temperature and a stirring speed of 600 r / min to obtain a precursor solution.
[0043] The mass ratio of the rod-shaped VO2 nanopowder to the volume of deionized water is 1g:62.5mL; the mass ratio of the rod-shaped VO2 nanopowder to polyvinylpyrrolidone-K30 is 6:1;
[0044] 2. Add hafnium tetrachloride to deionized water at room temperature and a stirring speed of 800 r / min, and stir and disperse for 4 hours to obtain a hafnium oxychloride suspension;
[0045] The mass ratio of hafnium tetrachloride to deionized water is 1 g:5 mL;
[0046] 3. Mixing and dispersing the precursor solution and the hafnium oxychloride suspension at room temperature and a stirring speed of 600 r / min for 6 hours to obtain a mixture;
[0047] The mass ratio of the VO2 nanopowder in the precursor solution to the hafnium tetrachloride in step 2 is 1.5:1;
[0048] 4. The mixture was subjected to a hydrothermal reaction at a temperature of 140°C for 24 hours. After hydrothermal reaction, it was centrifugally washed, dried and ground to obtain a heterogeneous core-shell structured VO2(M)@HfO2 powder.
[0049] The rod-shaped VO2 nanopowder described in step 1 is specifically prepared according to the following steps:
[0050] Vanadium pentoxide powder and oxalic acid dihydrate powder were sequentially added to deionized water, and mixed at room temperature and a stirring speed of 600 r / min for 8 hours to obtain a mixture. The mixture was hydrothermally reacted at a temperature of 240°C for 1 hour. After cooling to room temperature, the mixture was washed five times by alternating centrifugation with deionized water and ethanol, and then dried at a temperature of 60°C for 8 hours. After grinding, a dark black powder, namely VO2(B), was obtained. The dark black powder was heat-treated at an argon flow rate of 200 sccm and a temperature of 500°C for 2 hours, and finally cooled to room temperature to obtain a rod-shaped VO2 micro-nano powder, namely VO2(M).
[0051] The mass ratio of the vanadium pentoxide powder to the oxalic acid dihydrate powder is 1:2; the volume ratio of the vanadium pentoxide powder to deionized water is 1 g:40 mL.
[0052] The centrifugal washing in step 4 is specifically washing the sample by alternating centrifugation with deionized water and ethanol for 5 times; the drying in step 4 is specifically drying the sample at a temperature of 60° C. for 8 hours.
[0053] The average thickness of the shell layer in the heteromorphic core-shell structured VO2(M)@HfO2 powder prepared in step 4 of this embodiment is 14 nm.
[0054] Example 2: This example differs from Example 1 in that: during the preparation of the rod-shaped VO2 nanopowder in step 1, the mixture is hydrothermally reacted at 220°C for 6 hours; during the preparation of the rod-shaped VO2 nanopowder in step 1, the dark black powder is heat-treated at 500°C at an argon flow rate of 200 sccm for 1 hour; the mass ratio of the rod-shaped VO2 nanopowder to polyvinylpyrrolidone-K30 in step 1 is 4:1; the mass ratio of the VO2 nanopowder in the precursor solution in step 3 to the hafnium tetrachloride in step 2 is 1:1; and in step 4, the mixture is hydrothermally reacted at 160°C for 24 hours. Other procedures are the same as in Example 1.
[0055] The average thickness of the shell layer in the heteromorphic core-shell structured VO2(M)@HfO2 powder prepared in step 4 of this embodiment is 21 nm.
[0056] Example 3: This example differs from Example 1 in that, during the preparation of the rod-shaped VO2 nanopowder in Step 1, the mixture was hydrothermally reacted at 240°C for 3 hours; during the preparation of the rod-shaped VO2 nanopowder in Step 1, the dark black powder was heat-treated at 500°C for 1 hour at an argon flow rate of 200 sccm; and the mass ratio of the VO2 nanopowder in the precursor solution in Step 3 to the hafnium tetrachloride prepared in Step 2 was 0.75:1. Other procedures were the same as in Example 1.
[0057] The average thickness of the shell layer in the heteromorphic core-shell structured VO2(M)@HfO2 powder prepared in step 4 of this embodiment is 33 nm.
[0058] Comparative experiment: This comparative experiment differs from Example 3 in that the polyvinylpyrrolidone-K30 in step 1 is replaced with PVA. Other aspects are the same as Example 3.
[0059] The average thickness of the shell layer in the heteromorphic core-shell structured VO2(M)@HfO2 powder prepared in step 4 of this comparative experiment is 10 nm.
[0060] Figure 1 TEM comparison pictures of powders, (a) rod-shaped VO2 micro-nano powder described in step 1 of Example 1, (b) overall morphology of the heteromorphic core-shell structure VO2(M)@HfO2 powder prepared in Example 1, (c) high-magnification morphology of the heteromorphic core-shell structure VO2(M)@HfO2 powder prepared in Example 1; it can be seen from the figure that the prepared powder material has an obvious core-shell structure, the average thickness of the shell is 14nm, and the aspect ratio is about 100.
[0061] HfO2 powder, the rod-shaped VO2 micro-nano powder described in step 1 of Example 3, the heteromorphic core-shell structure VO2(M)@HfO2 powder prepared in Example 3, and the heteromorphic core-shell structure VO2(M)@HfO2 powder prepared in the comparative experiment were corroded in a strong acid (pH = 0) environment for 10 minutes, 20 minutes, and 30 minutes, respectively, to verify the corrosion resistance; the HfO2 powder was specifically prepared by repeating the processes of steps 2 and 4 of Example 3; Figure 2These are optical images of powders corroded in a strong acid (pH = 0) environment for 10 min, 20 min and 30 min, respectively, (a) HfO2 powder, (b) rod-shaped VO2 micro-nano powder described in step 1 of Example 3, (c) heteromorphic core-shell structure VO2(M)@HfO2 powder prepared in Example 3, (d) heteromorphic core-shell structure VO2(M)@HfO2 powder prepared in a comparative experiment; it can be seen from the figure that in a strong acid environment, HfO2 powder has good resistance to acid corrosion, the rod-shaped VO2 micro-nano powder is rapidly dissolved under acidic conditions, and the heteromorphic core-shell structure VO2(M)@HfO2 powder prepared in Example 3 has certain corrosion resistance under extreme acidic conditions; the material (d) using the same parameters but changing the surfactant to PVA is slightly better than pure VO2 in a strong acid environment, but it also clearly presents a transparent solution state after 30 minutes, proving that it is corroded by acid.
[0062] Figure 3 XRD patterns of the heteromorphic core-shell structured VO2(M)@HfO2 powders prepared in Examples 1 to 3. As can be seen from the figure, all diffraction peaks of the three groups of samples are related to the monoclinic phase of VO2(M) (JCPDS: 43-1051), and almost no impurity peaks are detected. The prepared powders are VO2(M)@HfO2. As the proportion of HfO2 increases, the crystallinity of the samples decreases.
[0063] Figure 4 The following are the Fourier transform infrared spectra of the heterogeneous core-shell structure VO2(M)@HfO2 powder prepared in Example 2 at low and high temperatures. As can be seen from the figure, the heterogeneous core-shell structure VO2(M)@HfO2 powder prepared in this example has an emissivity of 0.26 at 0°C and 0.51 at 70°C in the 8μm-14μm band. The emissivity test from 0°C to 70°C showed an emissivity change of 0.25. Under accelerated heat aging conditions at 60°C and 90% humidity, after 30 days in the 8μm-14μm band, the emissivity at 0°C was 0.28 and the emissivity at 70°C was 0.52. The emissivity test from 0°C to 70°C showed an emissivity change of 0.24.
[0064] The heterogeneous core-shell VO2(M)@HfO2 powder prepared in Example 1 exhibited an emissivity of 0.29 at a low temperature of 20°C and 0.44 at a high temperature of 70°C in the 8μm-14μm wavelength range. Emissivity testing from 0°C to 70°C revealed an emissivity change of 0.15. In an accelerated damp-heat aging test at 60°C and 90% humidity, after 30 days, the emissivity in the 8μm-14μm wavelength range was 0.30 at a low temperature of 0°C and 0.46 at a high temperature of 70°C. Emissivity testing from 0°C to 70°C revealed an emissivity change of 0.16.
[0065] The heterogeneous core-shell VO2(M)@HfO2 powder prepared in Example 3 exhibited an emissivity of 0.31 at 0°C and 0.71 at 70°C in the 8μm-14μm wavelength band. Emissivity testing from 0°C to 70°C revealed an emissivity change of 0.40. In an accelerated damp-heat aging test at 60°C and 90% humidity, after 30 days, the emissivity in the 8μm-14μm wavelength band was 0.30 at 0°C and 0.69 at 70°C. Emissivity testing from 0°C to 70°C revealed an emissivity change of 0.39.
Claims
1. A method for preparing a uniformly coated heteromorphic core-shell structure for use in the infrared band, characterized in that It is carried out in the following steps:
1. Ultrasonic dispersion of the heteromorphic core in deionized water, then adding a surfactant and stirring at room temperature to obtain a core precursor solution; 2. Add the shell precursor to deionized water under stirring at room temperature to obtain a shell precursor solution / suspension; 3. Mixing and dispersing the core precursor solution and the shell precursor solution / suspension at room temperature with stirring to obtain a mixture; Fourth, the mixture is reacted, and then centrifugally washed, dried and ground to obtain a uniformly coated heteromorphic core-shell structure suitable for use in the infrared band.
2. The method for preparing a uniformly coated heteromorphic core-shell structure for use in the infrared band according to claim 1, characterized in that The mass ratio of the heteromorphic core described in step 1 to the volume ratio of deionized water is 1g: (62.5~125)mL; the mass ratio of the heteromorphic core described in step 1 to the surfactant is (3.2~12.8):1; the surfactant described in step 1 is polyvinylpyrrolidone-K30, CTAB, polyvinylpyrrolidone-K60 or dehydrated sorbitan fatty acid ester.
3. The method for preparing a uniformly coated heteromorphic core-shell structure for use in the infrared band according to claim 1, characterized in that In step 1, the shaped core is ultrasonically dispersed in deionized water for 30 min to 120 min at a power of 40 W to 150 W, and then a surfactant is added and stirred for 30 min to 120 min at room temperature and a stirring speed of 400 r / min to 1500 r / min to obtain a core precursor solution.
4. The method for preparing a uniformly coated heteromorphic core-shell structure for use in the infrared band according to claim 1, characterized in that The special-shaped core described in step 1 is a rod-shaped VO2 micro-nano powder, which is specifically prepared according to the following steps: Vanadium pentoxide powder and oxalic acid dihydrate powder are sequentially added to deionized water, and mixed for 8 h to 12 h at room temperature and a stirring speed of 400 r / min to 1500 r / min to obtain a mixture. The mixture is hydrothermally reacted at a temperature of 200°C to 240°C for 1 h to 6 h. After cooling to room temperature, the mixture is alternately centrifuged and washed 3 to 5 times with deionized water and ethanol, and then dried at a temperature of 60°C to 80°C for 8 h to 12 h. After grinding, a dark black powder, namely VO2(B), is obtained. The dark black powder is heat-treated for 10 min to 2 h at an argon flow rate of 100 sccm to 400 sccm and a temperature of 500°C to 600°C, and finally cooled to room temperature to obtain rod-shaped VO2 micro-nano powder, namely VO2(M). The mass ratio of the vanadium pentoxide powder to the oxalic acid dihydrate powder is 1:(2-5); the volume ratio of the vanadium pentoxide powder to deionized water is 1g:(40-50)mL.
5. The method for preparing a uniformly coated heteromorphic core-shell structure for use in the infrared band according to claim 1, characterized in that The volume ratio of the shell precursor described in step 2 to deionized water is 1 g: (5-10) mL; the shell precursor described in step 2 is hafnium tetrachloride, TEOS or calcium chloride.
6. The method for preparing a uniformly coated heteromorphic core-shell structure for use in the infrared band according to claim 1, characterized in that In step 2, the shell precursor is added to deionized water at room temperature and a stirring speed of 400 r / min to 1500 r / min, and stirred and dispersed for 1 h to 12 h.
7. The method for preparing a uniformly coated heteromorphic core-shell structure for use in the infrared band according to claim 1, characterized in that The mass ratio of the heteromorphic core in the core precursor solution described in step 3 to the shell precursor in step 2 is (1~5):1; in step 3, the core precursor solution and the shell precursor solution / suspension are mixed and dispersed at room temperature and a stirring speed of 400r / min~1200r / min for 6h~24h.
8. The method for preparing a uniformly coated heteromorphic core-shell structure for use in the infrared band according to claim 1, characterized in that The reaction described in step 4 is specifically a hydrothermal reaction at a temperature of 100°C to 160°C for 12h to 24h; the centrifugal washing described in step 4 is specifically a centrifugal washing using deionized water and ethanol alternately for 3 to 5 times; the drying described in step 4 is specifically a drying at a temperature of 60°C to 80°C for 8h to 24h.
9. The method for preparing a uniformly coated heteromorphic core-shell structure for use in the infrared band according to claim 1, characterized in that The shell layer of the uniformly coated heteromorphic core-shell structure for use in the infrared band prepared in step 4 is hafnium oxide, silicon oxide or calcium fluoride, and has a thickness of 5nm~50nm.
10. Application of a uniformly coated heteromorphic core-shell structure prepared as claimed in claim 1 for use in infrared bands, characterized in that It is used for infrared band control.