A medium-high-entropy rare earth-based cesium tungsten bronze ceramic powder, thin film, smart window and preparation and application thereof

Abstract

This invention discloses a medium-high entropy rare earth-based cesium tungsten bronze ceramic powder, thin film, smart window, and its preparation and application. The chemical formula of the ceramic powder is Cs. 3x RE x WO3 and RE are selected from any two or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Td, Dy, Ho, Er, Tm, Yb, Lu, and Sc; the molar ratio of all rare earth ions in RE is equal, and x is 0.022~0.037. This invention solves the problem that existing cesium tungsten bronze is difficult to balance with infrared shielding and transmittance, and its performance is still insufficient after doping. The ceramic powder prepared by the hydrothermal method has good structural stability and excellent defect control ability. Its thin film and smart window have both high visible light transmittance (>70%) and infrared shielding rate (94.1% and 99.9% at 1500 nm, respectively) and good thermal control ability.

Description

Technical Field

[0001] This invention relates to a rare earth-based cesium tungsten bronze ceramic powder, specifically to a medium-high entropy rare earth-based cesium tungsten bronze ceramic powder, thin film, smart window, and its preparation and application. Background Technology

[0002] For glass coatings to achieve excellent heat insulation, the infrared shielding effect of the powder is a key factor affecting the performance of the heat-insulating coating, especially in southern regions where temperatures often exceed 35°C and there is strong solar radiation. Excessive building energy consumption also has a significant negative impact on the environment. Near-infrared light accounts for 52% of sunlight, and ordinary coatings cannot block the radiation energy of near-infrared light. Therefore, in order to achieve energy-saving effects for glass windows, there is an urgent need to develop a new type of coating with heat insulation function.

[0003] Common nanoparticles used in transparent heat-insulating coatings include ATO, ITO, lanthanide borides (LaB6), and vanadium dioxide (VO2). However, they also face some challenges. For these common transparent heat-insulating materials, ATO and ITO are expensive raw materials with high manufacturing costs, and they generally only shield infrared light above 1500nm. Lanthanide borides have complex manufacturing processes, often involving high-temperature hot pressing, making commercialization difficult. VO2, on the other hand, violates the principles of green chemistry, as the raw materials used in its preparation are harmful to human health. Therefore, there is an urgent need to develop nanoparticles for transparent heat-insulating coatings that offer wide-band shielding, simple manufacturing processes, low cost, and environmental friendliness. Although cesium tungsten bronze has superior near-infrared light shielding performance compared to ATO and ITO, how to simultaneously achieve high infrared shielding performance and high visible light transmittance remains a significant challenge.

[0004] In recent years, rare earth elements have become promising near-infrared responsive materials due to their excellent physicochemical properties. In the field of transparent thermal insulation, cesium tungsten bronze has attracted widespread attention due to its excellent near-infrared shielding capabilities in the 780-2500 nm wavelength range, resulting from the LSPR effect and small polaron transfer effect. The 4f electron subshell of lanthanides possesses a rich energy level structure, which can form complementary absorption bands with the free carrier absorbers in cesium tungsten bronze, enabling it to achieve broad-spectrum photothermal conversion. Solar radiation has the highest energy concentration between 780-2500 nm, and the multi-level transitions of rare earth ions fall precisely within this range. Therefore, rare earth doping can effectively block NIR thermal radiation. Existing document 1 (Chinese invention patent application with publication number CN117448980A) provides a nano-multimetal-doped tungsten bronze thermal storage fiber and its preparation method. The fiber is prepared from 10-60 parts by mass of a thermal storage slurry and 40-70 parts by mass of a polymer material. The thermal storage slurry is prepared from nano-multimetal-doped tungsten bronze, a dispersion medium, a dispersant, and a defoamer. This fiber uses simple raw materials, employing multi-ion-doped tungsten bronze, achieving excellent near-infrared absorption without introducing other materials. This avoids compatibility issues in compounding various compounds and gelation phenomena during subsequent milling due to different dispersant selections, improving the efficiency of thermal storage fiber preparation and saving production costs. However, document 1 only uses conventional multimetal-doped tungsten bronze, resulting in weak lattice distortion and LSPR effect, limited near-infrared absorption and photothermal performance, insufficient structural stability and defect control capabilities, and poor thermal insulation performance. Summary of the Invention

[0005] The purpose of this invention is to provide a medium-high entropy rare earth-based cesium tungsten bronze ceramic powder, thin film, smart window, and its preparation and application. It solves the problem that existing cesium tungsten bronzes are difficult to balance infrared shielding and light transmittance, and their performance is still insufficient after doping. The ceramic powder prepared by the hydrothermal method has good structural stability and excellent defect control ability. Its thin film and smart window have both high visible light transmittance and infrared shielding rate and good thermal control ability.

[0006] To achieve the above objectives, the present invention provides a medium-high entropy rare-earth-based cesium tungsten bronze ceramic powder for absorbing high infrared radiation, the chemical formula of which is Cs. 3x RE x WO3, wherein RE is selected from any one or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Td, Dy, Ho, Er, Tm, Yb, Lu and Sc; the molar ratio of all rare earth ions in RE is equal, and the value of x is 0.022~0.037.

[0007] The high-entropy rare-earth-based cesium tungsten bronze ceramic powder of this invention introduces multiple rare-earth elements (≥4 types) to form a high-entropy system, resulting in a highly disordered lattice. This thermodynamically stabilizes oxygen vacancy defects and inhibits their recombination. The combination of different rare earth elements broadens the absorption bandwidth and improves photothermal conversion efficiency. In terms of infrared absorption performance, it exhibits lattice distortion effect, high-entropy stabilization effect, enhanced defect control capability, and strong tunability of optical properties. Specifically, the lattice distortion effect is achieved by using multiple rare-earth ions (such as Nd...). 3+ 、Sm 3+ 、Tb 3+ and Dy 3+ (2) High-entropy stabilization effect: Multi-component configuration brings higher configuration entropy, reduces system free energy, improves crystal structure stability, and enhances the thermal stability and environmental durability of the material; (3) Enhanced defect control capability: High-entropy effect promotes W 5+ The formation of oxygen vacancy concentration and the increase of oxygen vacancy concentration optimize the free carrier concentration and improve the carrier mobility, thereby significantly enhancing the light absorption and photothermal conversion performance in the near-infrared region; (4) Strong optical performance tunability: By adjusting the types and proportions of rare earth elements, the absorption mechanism of LSPR and small polarons can be precisely controlled, thereby taking into account both high visible light transmittance and excellent near-infrared shielding performance, and realizing the synergistic optimization of visible light transmittance and near-infrared shielding performance.

[0008] Preferably, the RE is selected from any 2 to 4 elements from La, Ce, Pr, Nd, Sm, Eu, Gd, Td, Dy, Ho, Er, Tm, Yb, Lu and Sc, and the molar ratio of all rare earth ions is equal, and the value of x is 0.022 to 0.037.

[0009] Preferably, the RE is any two or more of Nd, Sm, Tb and Dy, and the molar ratio of all rare earth ions is equal, and the value of x is 0.022~0.037.

[0010] More preferably, the chemical formula is Cs 3a Tb a Dy a WO3, Cs 3m Nd m Tb m Dy m WO3 and Cs 3x Nd x Sm x Tb x Dy xWO3, where a is 0.037, m is 0.0275, and x is 0.022.

[0011] Regarding the rare earth ions, this invention selects Nd, Sm, Tb, and Dy because they exhibit different 4f electron configurations. 3+ and Sm 3+ With partially filled 4f orbitals, it provides abundant 4f-4f transition channels in the visible and near-infrared regions, contributing to native absorption; in contrast, Tb 3+ and Dy 3+ In a nearly filled or more than half-filled 4f configuration, stronger crystal field splitting and spin-orbit coupling effects are observed, thus broadening the absorption bandwidth. Furthermore, with the increase in the types of rare earth ions introduced, the configurational entropy of the system significantly increases, thereby thermodynamically stabilizing oxygen vacancy defects and suppressing their recombination, which is beneficial for controlling the band structure and enhancing the absorption capacity for near-infrared light. Therefore, compared with single rare earth doping, multi-component rare earth systems can significantly improve the near-infrared shielding performance of materials. The molar ratio of rare earth ions has a nonlinear effect on material performance. When the rare earth doping amount is low, the oxygen vacancy concentration generated in the system is limited, and the free carrier concentration is low, making it difficult to form effective localized surface plasmon resonance absorption. When the doping amount is moderate, the oxygen vacancy concentration and carrier concentration reach optimal matching, thus achieving excellent near-infrared absorption performance. However, when the doping amount is too high, excessive lattice distortion leads to enhanced carrier scattering, thereby reducing visible light transmittance and hindering the overall optimization of optical performance. Therefore, by rationally selecting various rare earth ions and optimizing their molar ratio, this invention achieves synergistic regulation of oxygen vacancy concentration, carrier concentration, and lattice structure, thereby significantly improving near-infrared shielding capability while ensuring high visible light transmittance.

[0012] This invention provides a method for preparing medium-high entropy rare earth-based cesium tungsten bronze ceramic powder as described above, the method comprising: (1) (NH4)6H2W 12 O 40 ·xH2O is added to an alcoholic solution containing tartaric acid, followed by an aqueous solution containing rare earth ions and cesium ions. The mixture is then thoroughly mixed, and an oleylamine solution is added. The mixture is then subjected to a hydrothermal reaction at 180 °C to 250 °C to generate the precursor. The molar ratio of rare earth ions to cesium ions in the aqueous solution containing rare earth ions and cesium ions is 1:3. (2) Wash and dry the precursor; (3) The dried precursor was sintered in an inert gas at 500 °C to 800 °C to obtain medium-high entropy rare earth-based cesium tungsten bronze ceramic powder.

[0013] Preferably, the (NH4)6H2W12 O 40 The ratio of the amount of tungsten in xH2O to the total amount of metal ions in the aqueous solution containing rare earth ions and cesium ions is (10~30):11.

[0014] Preferably, the (NH4)6H2W 12 O 40 The ratio of the amount of tungsten in xH2O to the total amount of metal ions in the aqueous solution containing rare earth ions and cesium ions is (15~25):11.

[0015] Preferably, the hydrothermal reaction time is 24-96 h; or / and, the washing is performed using cyclohexane; or / and, the drying temperature is 60 °C-80 °C; or / and, the inert atmosphere is selected from nitrogen and argon, or two or more; or / and, the sintering heating rate is 5 °C / min, the time is 0.5-3 h, and the furnace is cooled after sintering.

[0016] This invention provides an application of the medium-high entropy rare earth-based cesium tungsten bronze ceramic powder as described above in the field of thermal insulation.

[0017] Preferably, the application includes heat-insulating glass used in buildings, furniture, and automobiles.

[0018] Preferably, the application includes forming a medium-high entropy rare earth-based cesium tungsten bronze thin film from the aforementioned medium-high entropy rare earth-based cesium tungsten bronze ceramic powder, specifically comprising: The medium-high entropy rare earth-based cesium tungsten bronze powder was added to water and then to a polyvinyl alcohol solution to prepare a coating, which was then spin-coated into a thin film.

[0019] The process of fabricating a high-entropy rare-earth-based cesium tungsten bronze smart window from the aforementioned high-entropy rare-earth-based cesium tungsten bronze ceramic powder includes the following steps: Poly(N-isopropylacrylamide) (NIPAM) and N,N'-methylenebisacrylamide (MBA) are placed in distilled water and stirred until completely dissolved and evenly distributed. The mixture is then placed in an ice bath and allowed to stand. Tetramethylethylenediamine (TEMED) and potassium persulfate (KPS) are then added and allowed to stand to obtain PNIPAM gel.

[0020] By injecting PNIPAM hydrogel into a sealed double-layer quartz glass, and coating a medium-high entropy rare earth-based cesium tungsten bronze thin film on one side of the quartz glass, a medium-high entropy rare earth-based cesium tungsten bronze smart window can be prepared.

[0021] More preferably, the mass ratio of the medium-high entropy rare earth-based cesium tungsten bronze powder to water is 1:(1~5); or / and, the mass concentration of the polyvinyl alcohol solution is 5%~10%; or / and, the molar ratio of the poly(N-isopropylacrylamide) (NIPAM) to N,N'-methylenebisacrylamide (MBA) is 1:(40~50); or / and, the mass of the tetramethylethylenediamine is 10~30 μL, and the mass of the potassium persulfate is 0.010~0.030 g; or / and, the inner layer thickness of the double-layer quartz glass is 0.5~2 mm.

[0022] This invention discloses a medium-high entropy rare earth-based cesium tungsten bronze ceramic powder, thin film, smart window, and its preparation and application, which solves the problem that existing cesium tungsten bronzes are difficult to balance in terms of infrared shielding and light transmittance, and that their performance is still insufficient after doping. It has the following advantages: 1. The medium-high entropy rare-earth cesium tungsten bronze powder prepared by this invention exhibits good structural stability. XRD test results show that the high entropy effect enables multi-component ions to form a stable solid solution structure in the crystal lattice; entropy increase reduces the system's free energy, maintaining crystal structure stability even under high temperature or complex environments. This medium-high entropy rare-earth cesium tungsten bronze powder possesses excellent defect control capabilities. X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance spectroscopy (ESR) analyses show that entropy increase promotes W 6+ To W 5+ The transformation introduces an appropriate amount of oxygen vacancies, increases the free carrier concentration, and improves electron mobility, thereby enhancing the LSPR strength of the material.

[0023] 2. This invention employs a hydrothermal method to prepare high-infrared-absorbing, medium-high entropy rare-earth-based cesium tungsten bronze ceramic powder, which boasts advantages such as low-temperature synthesis, small particle size, and controllable nanoparticle morphology. The high-infrared-absorbing, medium-high entropy rare-earth-based cesium tungsten bronze thin film and smart window prepared by this invention possess both high visible light transmittance and infrared shielding efficiency. Both exhibit high visible light transmittance (>70%), meeting daily lighting requirements. Regarding near-infrared (1500 nm) shielding performance, the thin film achieves a near-infrared shielding efficiency of 94.1%, while the smart window reaches a high near-infrared shielding efficiency of 99.9%. Due to the excellent near-infrared absorption and photothermal conversion properties of high-entropy rare-earth cesium tungsten bronze, its thin film and smart window exhibit good thermal regulation capabilities: in outdoor heat insulation experiments, compared to blank glass, they can reduce temperatures by approximately 4 °C and 10 °C, respectively. Attached Figure Description

[0024] Figure 1 This is a process flow diagram of the method for preparing high-entropy rare-earth-based cesium tungsten bronze ceramic powder in Example 1 of the present invention.

[0025] Figure 2 Cs obtained in Example 1 of this invention 3x Nd x Smx Tb x Dy x XRD pattern of WO3 (x = 0.022) ceramic powder.

[0026] Figure 3 Cs obtained in Example 1 of this invention 3x Nd x Sm x Tb x Dy x SEM and EDS images of WO3 (x = 0.022) ceramic powder.

[0027] Figure 4 Cs obtained in Example 2 of this invention 3m Nd m Tb m Dy m XRD pattern of WO3 (m = 0.0275) ceramic powder.

[0028] Figure 5 Cs obtained in Example 2 of this invention 3m Nd m Tb m Dy m SEM and EDS images of WO3 (m = 0.0275) ceramic powder.

[0029] Figure 6 Cs obtained in Example 3 of this invention 3a Tb a Dy a XRD pattern of WO3 (a = 0.037) ceramic powder.

[0030] Figure 7 Cs obtained in Example 3 of this invention 3a Tb a Dy a SEM and EDS images of WO3 (a = 0.037) ceramic powder.

[0031] Figure 8 XPS images of the medium-high entropy rare earth-based cesium tungsten bronzes prepared in Examples 1-3 of this invention.

[0032] Figure 9 The electron paramagnetic resonance (ESR) spectra of the medium-high entropy rare earth-based cesium tungsten bronze prepared in Examples 1-3 of this invention are shown.

[0033] Figure 10 The infrared absorption rate diagrams are for the medium-high entropy rare earth-based cesium tungsten bronzes prepared in Examples 1-3 of this invention.

[0034] Figure 11The image shows the optical performance of the thin film and smart window obtained in Example 4 of this invention.

[0035] Figure 12 This diagram illustrates the development of the optical properties of this invention compared to existing thin films and smart windows.

[0036] Figure 13 The figure shows the results of an outdoor test of the temperature change of the thin film and smart window prepared in Example 4 of this invention under the same light. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1 A high-entropy rare-earth-based cesium tungsten bronze Cs 3x Nd x Sm x Tb x Dy x Preparation method of WO3 (x = 0.022) ceramic powder, such as Figure 1 The diagram shows the process flow chart of the method for preparing high-entropy rare-earth-based cesium tungsten bronze ceramic powder in Embodiment 1 of the present invention. The method includes the following steps: (1) Weigh 0.0500 mol of tartaric acid, prepare 50 mL of 1 mol / L tartaric acid ethanol solution, and add 0.0001 mol of (NH4)6H2W 12 O 40 Add xH2O to the above solution and stir well. Weigh out 0.000198 mol of Cs2CO3 and 0.000132 mol of Nd(NO3)3, Sm(NO3)3, Tb(NO3)3 and Dy(NO3)3 respectively, dissolve them in 10 mL of water and stir well. After mixing the two evenly, add 10 mL of oleylamine solution, pour into a polytetrafluoroethylene liner, and carry out a hydrothermal reaction. Control the reaction temperature at 250 °C and the reaction time at 96 h. The amount of Nd(NO3)3, Sm(NO3)3, Tb(NO3)3 and Dy(NO3)3 is 0.000033 mol each.

[0039] (2) The product obtained in step (1) was washed three times with cyclohexane and then placed in an oven and dried at 60 °C for 24 h. (3) The sample obtained in step (2) is placed in a tube furnace for calcination. Under a gas atmosphere of 10% H2 + 90% Ar, the calcination temperature is controlled at 500 °C, the heating rate is 5 °C / min, and the holding time is 2 h to obtain Cs. 3x Nd x Sm x Tb x Dy x WO3 (x = 0.022) ceramic powder, denoted as CWO-NSTD.

[0040] like Figure 2 As shown, the Cs obtained in Example 1 of this invention 3x Nd x Sm x Tb x Dy x XRD pattern of WO3 (x = 0.022) ceramic powder, scanned at 5° / min. The characteristic peaks of its XRD pattern are similar to those of Cs. 0.32 The WO3 standard card is consistent, indicating that high-entropy rare-earth cesium tungsten bronze has been successfully synthesized. The high-entropy effect enables multi-component ions to form a stable solid solution structure in the crystal lattice.

[0041] like Figure 3 As shown, the Cs obtained in Example 1 of this invention 3x Nd x Sm x Tb x Dy x SEM and EDS images of WO3 (x = 0.022) ceramic powder. The SEM image shows that the powder prepared by this method has a spherical structure and uniform particle size. The EDS image shows that various rare earth ions are uniformly distributed on the powder, achieving uniformity of rare earth elements.

[0042] Example 2 A high-entropy rare-earth-based cesium tungsten bronze Cs 3m Nd m Tb m Dy m A method for preparing WO3 (m = 0.0275) ceramic powder, comprising the following steps: (1) Weigh 0.0500 mol of tartaric acid, prepare 50 mL of 1 mol / L tartaric acid ethanol solution, and add 0.0001 mol of (NH4)6H2W 12 O 40Add xH2O to the above solution and stir well. Weigh out 0.0002475 mol of Cs2CO3 and 0.000165 mol of Nd(NO3)3, Tb(NO3)3 and Dy(NO3)3 respectively, dissolve them in 10 mL of water and stir well. After mixing the two evenly, add 10 mL of oleylamine solution, pour into a polytetrafluoroethylene liner, and carry out a hydrothermal reaction. Control the reaction temperature at 200°C and the reaction time at 72 h. The amount of Nd(NO3)3, Tb(NO3)3 and Dy(NO3)3 is 0.000055 mol each.

[0043] (2) The product obtained in step (1) was washed three times with cyclohexane and then placed in an oven and dried at 80 °C for 12 h. (3) The sample obtained in step (2) is placed in a tube furnace for calcination. Under a gas atmosphere of 10% H2 + 90% Ar, the calcination temperature is controlled at 700 °C, the heating rate is 5 °C / min, and the holding time is 3 h to obtain Cs. 3m Nd m Tb m Dy m WO3 (m = 0.0275) ceramic powder, denoted as CWO-NTD.

[0044] like Figure 4 As shown, the Cs obtained in Example 2 of this invention 3m Nd m Tb m Dy m XRD pattern of WO3 (m = 0.0275) ceramic powder, scanned at 5° / min. The characteristic peaks of its XRD pattern are similar to those of Cs. 0.32 The results are consistent with the WO3 standard card, indicating that high-entropy rare-earth cesium tungsten bronze has been successfully synthesized.

[0045] like Figure 5 As shown, the Cs obtained in Example 2 of this invention 3m Nd m Tb m Dy m SEM and EDS images of WO3 (m = 0.0275) ceramic powder. The SEM image shows that the powder prepared by this method has a spherical structure and uniform particle size. The EDS image shows that various rare earth ions are uniformly distributed on the powder, achieving uniformity of rare earth elements.

[0046] Example 3 A medium-entropy rare-earth-based cesium tungsten bronze (Cs) 3a Tb a Dy aA method for preparing WO3 (a = 0.037, denoted as CWO-TD) ceramic powder, comprising the following steps: (1) Weigh 0.0500 mol of tartaric acid, prepare 50 mL of 1 mol / L tartaric acid ethanol solution, and add 0.0001 mol of (NH4)6H2W 12 O 40 Add xH2O to the above solution and stir well. Weigh out 0.00033 mol of Cs2CO3 and 0.00022 mol of Tb(NO3)3 and Dy(NO3)3 respectively, dissolve them in 10 mL of water and stir well. After mixing the two evenly, add 10 mL of oleylamine solution, pour into a polytetrafluoroethylene liner, and carry out a hydrothermal reaction. Control the reaction temperature at 180°C and the reaction time at 24 h. The amount of Tb(NO3)3 and Dy(NO3)3 is 0.00011 mol each.

[0047] (2) The product obtained in step (1) was washed three times with cyclohexane and then placed in an oven and dried at 80 °C for 8 h. (3) The sample obtained in step (2) is placed in a tube furnace for calcination. Under a gas atmosphere of 10% H2 + 90% Ar, the calcination temperature is controlled at 800 °C, the heating rate is 5 °C / min, and the holding time is 3 h to obtain Cs. 3a Tb a Dy a WO3 (a = 0.037) ceramic powder, denoted as CWO-TD.

[0048] like Figure 6 As shown, the Cs obtained in Example 3 of this invention 3a Tb a Dy a XRD pattern of WO3 (a = 0.037) ceramic powder, scanned at 5° / min. The characteristic peaks of its XRD pattern are similar to those of Cs. 0.32 The results are consistent with the WO3 standard card, indicating that the medium-entropy rare-earth cesium tungsten bronze has been successfully synthesized.

[0049] like Figure 7 As shown, the Cs obtained in Example 3 of this invention 3a Tb a Dy a SEM and EDS images of WO3 (a = 0.037) ceramic powder. The SEM image shows that the powder prepared by this method has a spherical structure and uniform particle size. The EDS image shows that various rare earth ions are uniformly distributed on the powder, achieving uniformity of rare earth elements.

[0050] Example 4 A high-entropy rare-earth-based cesium tungsten bronze Cs3x Nd x Sm x Tb x Dy x A method for preparing WO3 (x = 0.022, denoted as CWO-NSTD) thin films, comprising the following steps: (1) The high-entropy rare earth-based cesium tungsten bronze CWO-NSTD prepared in Example 1 was added to water at a mass ratio of 1:5, and then thoroughly ground and ultrasonically dispersed to prepare a CWO-NSTD dispersion. (2) Add 1 g of dispersion to 5 mL of 5% polyvinyl alcohol solution, stir for 40 min, and coat it onto quartz glass (5 cm × 5 cm × 0.1 cm) by spin coating to obtain CWO-NSTD film; A high-entropy rare-earth-based cesium tungsten bronze Cs 3x Nd x Sm x Tb x Dy x A method for preparing a WO3 (x = 0.022, denoted as CWO-NSTD) smart window, comprising the following steps: (1) 0.1 mol NIPAM (poly(N-isopropylacrylamide)) and 0.002 mol MBA (N,N'-methylenebisacrylamide) were placed in 10 mL of distilled water at a molar ratio of 50:1. The mixture was stirred until it was completely dissolved and evenly distributed. The mixture was placed in an ice bath and allowed to stand for about 10 minutes. Then, 10 μL TEMED (tetramethylethylenediamine) and 0.010 g KPS (potassium persulfate) were added. The mixture was allowed to stand for a certain period of time. The specific time was not fixed. The mixture was allowed to stand until the system gelled, and then PNIPAM hydrogel was obtained. (2) Inject PNIPAM hydrogel into a sealed double-layer quartz glass with an inner layer thickness of 2 mm, and then coat a CWO-NSTD / PVA film (the above-mentioned CWO-NSTD film) on one side of the quartz glass to prepare the CWO-NSTD / PNIPAM smart window.

[0051] The optical performance of the thin film and smart window prepared in Example 4 of this invention, along with existing thin films and smart windows, was analyzed. Specifically, a UV-Vis-NIR spectrophotometer (Carry 5000, Agilent Technologies, USA) was used to test the optical performance of the thin film and smart window, with a test wavelength range of 300–2500 nm. Baseline calibration was performed using air as a blank before testing. During the testing process, the transmittance spectra of the thin film and smart window were measured at room temperature (25 °C).

[0052] like Figure 11The figure shows the optical performance of the film and smart window prepared in Example 4 of the present invention, where Blank is the blank control; PVA is polyvinyl alcohol; PNIPAM is poly(N-isopropylacrylamide); CWO-NSTD film is the CWO-NSTD film prepared in Example 4 of the present invention; and CWO-NSTD / PNIPAM is the CWO-NSTD / PNIPAM smart window prepared in Example 4 of the present invention.

[0053] like Figure 12 The diagram shows the development status of the optical properties of this invention compared to existing thin films and smart windows. [1-12] , where CWO-NSTD film is the CWO-NSTD film prepared in Example 4 of the present invention; CWO-NSTD / PNIPAM is the CWO-NSTD / PNIPAM smart window prepared in Example 4 of the present invention; References [1]: Wu M, Shi Y, Li R, et al. SpectrallySelective Smart Window with High Near-Infrared Light Shielding and Controllable Visible Light Transmittance [J]. ACS Appl Mater Interfaces, 2018, 10(46): 39819–39827; [2]: Zhang H, Liu J, Shi F, et al. Controlling the Growth of Hexagonal Cs x WO3Nanorods by Li +-Doping to Further Improve Its NearInfrared Shielding Performance [J]. Sol Energy Mater Sol Cells, 2022, 238;[3]Tan Y, Lyu J, Zhang D, et al. Rbxcsywo3 Based Superhydrophobic TransparentThermal Insulation Film for Energy Saving [J]. Colloids Surf A PhysicochemEng Asp, 2024, 692: 133994;[4]Li X-H, Liu C, Feng S-P, et al. Broadband LightManagement with Thermochromic Hydrogel Microparticles for Smart Windows [J].Joule, 2019, 3(1): 290–302;[5]Jiang T, Zhao X, Yin X, et al. DynamicallyAdaptive Window Design with Thermo-Responsive Hydrogel for Energy Efficiency[J]. Appl Energy, 2021, 287: 116573;[6]Zhang H, Liu J, Shi F, et al. A NovelBidirectional Fast Self-Responsive PVA-PNIPAM / Li m Cs n WO3Composite Hydrogel forSmart Window Applications [J]. Chem Eng J, 2022, 431: 133353;[7]Liu S, Li Y,Wang Y, et al. Near-Infrared-Activated Thermochromic Perovskite Smart Windows[J]. Adv Sci, 2022, 9(14): 2106090;[8]Wang B, Wang Q, Zhu Y, et al. A Photo- / Thermo-Dual-Responsible Csx WO3 / PNIPAM复合水凝胶用于节能窗户 [J]。《材料研究快报》,2019年,6(8): 085708;[9] Chao L, Sun C, Li J, 等。核壳结构纳米晶Cs的透明隔热性能 x WO3@TiO2[J]。《纳米材料》,2022年,12(16): 2806;

[10] Chao L, Li J, Bao L, 等。镧钨青铜在可见光和近红外区域光学性能的理论与实验研究 [J]。《陶瓷国际》,2023年,49(12): 21017–21025;

[11] Shen B, Wang Y, Lu L, 等。通过阴离子掺杂增强Cs的光谱调制 x WO3纳米晶用于节能玻璃 [J]。《太阳能材料与太阳能电池》,2022年,236: 111519;

[12] Huang X-J, Bao J, Han Y, 等。具有优异光学性能的钨青铜纳米晶用于节能玻璃的可控合成及演化机制 [J]。《材料化学C》,2018年,6(29): 7783–7789。由 Figure 12 可知,现有高近红外屏蔽率(约99%)的Li m Cs nWO3 / PNIPAM smart windows typically have relatively low visible light transmittance (approximately 66%). While FCWO films have higher visible light transmittance (approximately 80%), their near-infrared shielding efficiency (approximately 92.5%) remains limited. Figure 12 Comparative analysis Figure 11 It has been found that the smart window prepared in Example 4 of this invention simultaneously achieves high visible light transmittance and excellent near-infrared shielding efficiency, surpassing previously reported tungsten bronze-based and polymer composite smart window systems. Specifically, the CWO-NSTD film exhibits a visible light transmittance as high as 84.1%, and a near-infrared shielding efficiency of 94.1% at 1500 nm. Furthermore, the CWO-NSTD / PNIPAM smart window maintains a relatively high transmittance of 70.0% and achieves an enhanced near-infrared shielding efficiency of up to 99.9%. Figure 12 Compared to existing systems (which typically involve a trade-off between visible light transparency and near-infrared blocking), this invention achieves a significantly improved balance, highlighting the effectiveness of high-entropy design strategies.

[0054] like Figure 13 The figure shows the results of an outdoor test of the temperature change of the thin film prepared in Example 4 of this invention and the smart window under the same illumination. Figure 13 It is known that the highest temperature of blank glass is approximately 45 °C, the peak temperature of the CWO-NSTD film is 41 °C, and the peak temperature of the CWO-NSTD / PNIPAM smart window is the lowest at 35 °C. Compared with blank glass, these temperatures are reduced by approximately 4 °C and 10 °C, respectively. This demonstrates the dynamic control potential of the CWO-NSTD / PNIPAM smart window. The PNIPAM layer provides the basis for temperature-sensitive response, while the CWO-NSTD layer provides the core function of near-infrared shielding. The synergistic effect of the two enables a smart window that combines high visible light transmittance with high infrared shielding efficiency.

[0055] Specifically, a 3D printed PLA model (8 × 8 × 8 cm) was used. 3 Outdoor testing was conducted. Except for the top, all outer surfaces of the cavity model were wrapped with aluminum foil to reduce lateral thermal conductivity and ensure unidirectional controllable sunlight exposure. Under outdoor sunlight conditions, a thermocouple probe placed at the bottom of the cavity was used to continuously monitor the air temperature inside the cavity.

[0056] Example 5 Performance Test XPS, ESR, and infrared absorption rate tests were performed on the medium-high entropy rare earth-based cesium tungsten bronzes prepared in Examples 1-3 of this invention.

[0057] like Figure 8The figures show XPS images of the medium-high entropy rare-earth-based cesium tungsten bronzes prepared in Examples 1-3 of this invention, where (a) CWO-TD is the product obtained in Example 3; (b) CWO-NTD is the product obtained in Example 2; and (c) CWO-NSTD is the product obtained in Example 1. Figure 8 The X-ray photoelectron spectroscopy (XPS) test results show that the W in Examples 1-3 of this invention 5+ The contents were 25.3%, 24.60%, and 24.10%, respectively, indicating that the addition of rare earth elements and the high entropy effect effectively promoted W 6+ Partial restoration.

[0058] like Figure 9 The figures show the electron paramagnetic resonance (ESR) spectra of the medium-high entropy rare-earth-based cesium tungsten bronzes prepared in Examples 1-3 of this invention, where CWO-NSTD is the product obtained in Example 1; CWO-NTD is the product obtained in Example 2; and CWO-TD is the product obtained in Example 3. Figure 9 Electron paramagnetic resonance (ESR) spectroscopy results show that the powders prepared in Examples 1-3 of this invention exhibit a characteristic resonance signal centered at g ≈ 2.003, and the signal intensity is high, indicating that they have a high oxygen vacancy concentration. Introducing an appropriate amount of oxygen vacancy is beneficial to enhancing the LSPR intensity of the material and enhancing the infrared absorption capability of the material.

[0059] like Figure 10 The image shows the infrared absorption rates of the medium-high entropy rare-earth-based cesium tungsten bronzes prepared in Examples 1-3 of this invention, where CWO-NSTD is the product obtained in Example 1; CWO-NTD is the product obtained in Example 2; and CWO-TD is the product obtained in Example 3. Figure 10 The infrared absorption rate test results show that the powders prepared in Examples 1-3 of this invention exhibit high average near-infrared absorption performance, which are 97.94%, 96.93%, and 96.52%, respectively.

[0060] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A medium-to-high entropy rare-earth-based cesium tungsten bronze ceramic powder, characterized in that, The chemical formula of the ceramic powder is Cs. 3x RE x WO3, wherein RE is selected from any two or more of La, Ce, Pr, Nd, Sm, Eu, Gd, Td, Dy, Ho, Er, Tm, Yb, Lu and Sc; The rare earth ions in the RE have the same molar ratio, and the value of x is 0.022~0.

037.

2. The medium-high entropy rare earth-based cesium tungsten bronze ceramic powder according to claim 1, characterized in that, The RE is selected from any 2 to 4 elements from La, Ce, Pr, Nd, Sm, Eu, Gd, Td, Dy, Ho, Er, Tm, Yb, Lu and Sc, and the molar ratio of all rare earth ions is equal, and the value of x is 0.022 to 0.

037.

3. The medium-high entropy rare earth-based cesium tungsten bronze ceramic powder according to claim 2, characterized in that, The RE is any two or more of Nd, Sm, Tb and Dy, and the molar ratio of all rare earth ions is equal, with x ranging from 0.022 to 0.

037.

4. The medium-high entropy rare earth-based cesium tungsten bronze ceramic powder according to claim 3, characterized in that, The chemical formula is Cs 3a Tb a Dy a WO3, Cs 3m Nd m Tb m Dy m WO3 and Cs 3x Nd x Sm x Tb x Dy x WO3, where a is 0.037, m is 0.0275, and x is 0.

022.

5. A method for preparing medium-high entropy rare earth-based cesium tungsten bronze ceramic powder as described in any one of claims 1 to 4, characterized in that, The method includes: (1) (NH4)6H2W 12 O 40 ·xH2O is added to an alcoholic solution containing tartaric acid, followed by an aqueous solution containing rare earth ions and cesium ions. The mixture is then thoroughly mixed, and an oleylamine solution is added. The mixture is then subjected to a hydrothermal reaction at 180 °C to 250 °C to generate the precursor. The molar ratio of rare earth ions to cesium ions in the aqueous solution containing rare earth ions and cesium ions is 1:

3. (2) Wash and dry the precursor; (3) The dried precursor was sintered in an inert gas at 500 °C to 800 °C to obtain medium-high entropy rare earth-based cesium tungsten bronze ceramic powder.

6. The medium-high entropy rare earth-based cesium tungsten bronze ceramic powder according to claim 5, characterized in that, The (NH4)6H2W 12 O 40 The ratio of the amount of tungsten in xH2O to the total amount of metal ions in the aqueous solution containing rare earth ions and cesium ions is (10~30):

11.

7. The medium-high entropy rare earth-based cesium tungsten bronze ceramic powder according to claim 6, characterized in that, The (NH4)6H2W 12 O 40 The ratio of the amount of tungsten in xH2O to the total amount of metal ions in the aqueous solution containing rare earth ions and cesium ions is (15~25):

11.

8. The medium-high entropy rare earth-based cesium tungsten bronze ceramic powder according to claim 5, characterized in that, The hydrothermal reaction time is 24~96h; and / or the washing is performed with cyclohexane; and / or the drying temperature is 60 °C~80 °C; and / or the inert atmosphere is selected from nitrogen and argon, or two or more of them; and / or the sintering heating rate is 5° / min and the time is 0.5~3h, followed by furnace cooling after sintering.

9. The application of the medium-high entropy rare earth-based cesium tungsten bronze ceramic powder as described in any one of claims 1 to 4 in the field of thermal insulation.

10. The application according to claim 9, characterized in that, This application includes insulated glass used in buildings, furniture, and automobiles.

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