A rare earth-based stannate high-entropy radiation refrigeration ceramic material, a preparation method and application thereof

Abstract

This invention discloses a rare-earth-based stannate high-entropy radiative cooling ceramic material and its preparation method. The invention employs a solid-state synthesis method to prepare the rare-earth-based stannate high-entropy ceramic material. The preparation process is simple, and the synthesized rare-earth-based stannate high-entropy ceramic material has high purity and can be applied on a large scale. On the one hand, the rare-earth ions exhibit excellent optical properties due to their unique electronic layers, showing high reflectivity in the visible-near-infrared band. On the other hand, by applying the high-entropy "lattice distortion" effect and introducing rare-earth elements with larger size differences, the degree of lattice distortion is further increased, resulting in high emissivity in the mid-infrared band for the rare-earth-based stannate high-entropy ceramic material.

Description

Technical Field

[0001] This invention belongs to the field of radiation cooling material preparation technology, specifically relating to a rare earth-based stannate high-entropy radiation cooling ceramic material, its preparation method, and its application. Background Technology

[0002] Solar energy at 50×10 per year 15 While solar energy brings immense benefits to the Earth, issues such as the heat island effect, energy consumption, and public safety are becoming increasingly prominent. Traditional cooling methods, such as air conditioning and electric fans, consume large amounts of electricity and generate significant carbon dioxide emissions, which worsen the human living environment. In recent years, daytime radiative cooling technology has attracted widespread attention both domestically and internationally due to its high shading capacity, excellent weather resistance, high near-infrared reflectivity, and high emissivity in the mid-infrared atmospheric window. This passive cooling method can significantly improve the human living environment. Numerous reports have confirmed the enormous application potential of radiative cooling technology in solving environmental and economic problems. For the same building, applying a radiative cooling coating to the roof can reduce electricity operating costs by nearly 20%. Therefore, radiative cooling coatings are widely used in construction, outdoor tents, grain storage station exteriors, and cooling fabrics. Traditional radiative cooling materials are composed of metal oxides (e.g., titanium dioxide, zinc oxide, silicon dioxide, zirconium dioxide, etc.). However, these metal oxide materials have certain limitations, such as low reflectivity, low emissivity, or poor chemical stability, which greatly limit the application of radiation cooling technology. Therefore, there is an urgent need to find new materials for radiation cooling. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a rare-earth-based stannate high-entropy ceramic material, its preparation method, and its application. This invention prepares a rare-earth-based stannate high-entropy ceramic material with high near-infrared reflectivity and high-medium infrared emissivity by adding high-entropy solid-solution rare earth elements (RE).

[0004] Through extensive experimental research, the inventors unexpectedly discovered that rare earth elements, due to their excellent chemical stability, low toxicity, pleochroism, and unique optical and magnetic properties, can significantly optimize material performance when introduced. In the visible-near-infrared region, stannate ions readily undergo grouping, and rare earth metal ions, acting as electron acceptors, and stannate ions, acting as ligands, readily undergo electronic transitions upon absorbing sufficient energy, thereby altering the band gap and improving optical performance. Simultaneously, the concept of high entropy was introduced, and the characteristics of ceramic materials were modified by adjusting the rare earth element composition design. This resulted in pyrochlore-structured stannate exhibiting high emissivity in the mid-infrared atmospheric window band (8–13 μm), meeting the upgrade demands of the current market.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] This invention provides a rare earth-based stannate high-entropy ceramic material, the chemical formula of which is as follows: RE2Sn2O7, wherein RE is selected from five of the following: Y, La, Nd, Sm, Eu, Gd, Ho, Er, Yb, and Lu.

[0007] According to the present invention, the rare earth-based stannate high-entropy ceramic material has a pyrochlore structure. Preferably, in the rare earth-based stannate high-entropy ceramic material, each rare earth element is uniformly distributed.

[0008] According to the present invention, the rare earth-based stannate high-entropy ceramic material has an average reflectance of 90-105% in the near-infrared band, preferably 95-105%, with exemplary values ​​of 98.90%, 100.26%, and 104.06%.

[0009] According to the present invention, the average emissivity of the rare earth-based stannate high-entropy ceramic material in the infrared band (8-13 μm) of the atmospheric window is 90-100%, preferably 91-96%, and exemplary values ​​are 91.38%, 93.07%, and 95.41%.

[0010] According to the present invention, the rare earth-based stannate high-entropy ceramic material is exemplarily (Y 0.2 La 0.2 Nd 0.2 Eu 0.2 Gd 0.2 )2Sn2O7、(Y 0.2 La 0.2 Sm 0.2 Eu 0.2 Lu 0.2 )2Sn2O7 or (Y 0.2 La 0.2 Gd 0.2 Yb 0.2 Lu 0.2 )2Sn2O7.

[0011] According to the present invention, the rare earth-based stannate high-entropy ceramic material is prepared by solid-state synthesis from raw materials including RE source and Sn source.

[0012] The present invention also provides a method for preparing the above-mentioned rare earth stannate-based high entropy ceramic material, the method comprising the following steps: mixing RE source and Sn source, and preparing rare earth stannate-based high entropy ceramic material by solid-state synthesis.

[0013] According to the present invention, the RE source is selected from five of the following: yttrium oxide (Y2O3), lanthanum oxide (La2O3), neodymium oxide (Nd2O3), samarium oxide (Sm2O3), europium oxide (Eu2O3), gadolinium oxide (Gd2O3), holmium oxide (Ho2O3), erbium oxide (Er2O3), ytterbium oxide (Yb2O3), and lutetium oxide (Lu2O3).

[0014] According to the present invention, the Sn source is tin dioxide (SnO2).

[0015] According to the present invention, the molar ratio of RE source to Sn source is 1:(0.5-5), and an exemplary ratio is 1:2.

[0016] According to the present invention, the RE source and Sn source are mixed by ball milling. For example, the RE source and Sn source are ball-milled in a solvent mixture. For example, the solvent can be an alcohol (exemplarily ethanol). The present invention does not particularly limit the content of ethanol, as long as it is enough to submerge the zirconia balls and each raw material in the ball mill jar.

[0017] According to the present invention, the solid-state synthesis method includes calcining the mixture obtained by mixing. The calcination temperature is 1500-1650℃, exemplarily 1500℃, 1600℃, and 1650℃; the calcination time of the solid-state synthesis method is 2-15h, preferably 2-6h, exemplarily 2h, 3h, 4h, 5h, and 6h; the heating rate of the solid-state synthesis method is 5-10℃ / min, exemplarily 10℃ / min.

[0018] According to the present invention, the solid-state synthesis method can involve multiple calcinations, preferably two. The calcination temperatures can be the same or different, and can be independently set at 1500-1650℃, exemplarily 1500℃, 1600℃, and 1650℃. The calcination times can also be the same or different, and can be independently set at 2-15 hours, preferably 2-6 hours, exemplarily 2 hours, 3 hours, 4 hours, 5 hours, and 6 hours. The heating rate of the solid-state synthesis method is 5-10℃ / min, exemplarily 10℃ / min. The present invention employs a multiple calcination method, resulting in more uniform grains in the prepared ceramic material, thus reducing crystal defects in high-entropy ceramics and improving the mechanical strength and wear resistance of the ceramic material. Simultaneously, it can optimize the crystal structure of the ceramic material to improve its crystallinity and stability.

[0019] According to the present invention, before calcination, the prepared mixed powder is dried and pressed into shape; exemplaryly, a pressing block is used for pressing, the diameter of the pressing block is 10-20 mm, exemplary is 10 mm, 15 mm, 20 mm; the pressure of the pressing block is 5-10 MPa, exemplary is 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa or 10 MPa; the pressing time of the pressing block is 20-50 s, exemplary is 20 s, 30 s, 40 s, 50 s.

[0020] According to the present invention, the preparation method of the rare earth-based stannate high-entropy ceramic material specifically includes the following steps:

[0021] (1) Using ethanol as a medium, the RE source and Sn source were ball-milled and mixed.

[0022] (2) The slurry formed by ball milling is dried and sieved to prepare a mixed powder, and the mixed powder is pressed into a blank;

[0023] (3) After calcining the green body prepared in step (2), a rare earth-based stannate high-entropy ceramic material is obtained.

[0024] According to the present invention, the method further includes step (4): crushing the rare earth-based stannate high-entropy ceramic material obtained in step (3); and ball milling it again.

[0025] According to the present invention, the method further includes step (5): pressing the high-purity, impurity-free composite powder material obtained in step (4) into a mold, calcining and crushing the prepared blank to obtain rare earth-based stannate high-entropy ceramic material.

[0026] According to the present invention, in step (1) or step (4), the rotation speed of the ball mill is 300 to 500 rpm, for example 400 rpm or 450 rpm, and the ball milling time is 1 to 10 hours, for example 5 hours or 10 hours; preferably, the working mode of the ball mill is to pause for 1 minute after every 4 minutes of working.

[0027] According to the present invention, in step (2) or step (4), the drying time is 10-24 hours, the drying temperature is 60-80℃, and the mesh size of the sieve used for sieving is 200-400 mesh.

[0028] According to the present invention, in step (5), the powder is pressed into a blank using a pressing block. For example, the diameter of the pressing block is 10-20 mm, exemplarily 10 mm, 15 mm, or 20 mm; the pressure of the pressing block is 5-15 MPa, exemplarily 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, or 10 MPa; and the pressing time of the pressing block is 20-50 s, exemplarily 20 s, 30 s, 40 s, or 50 s.

[0029] As an exemplary embodiment of the present invention, the preparation method of the rare earth-based stannate high-entropy ceramic material specifically includes the following steps:

[0030] (1) Mix the RE source and Sn source and ball mill them with ethanol as the medium;

[0031] (2) The ball-milled slurry is dried, sieved, and pressed into tablets to obtain the preform;

[0032] (3) Calcine and heat-keep the blank obtained in step (2) to obtain a raw blank;

[0033] (4) After crushing the green body obtained in step (3), the powder is ball-milled with ethanol as the medium, and then dried, sieved and pressed into tablets to obtain the green body.

[0034] (5) The blank obtained in step (4) is calcined again, kept warm, and crushed to obtain the target product, rare earth-based stannate high-entropy ceramic material.

[0035] This invention also provides the application of the rare-earth-based stannate high-entropy ceramic material in building exterior walls, fabrics, and outdoor tents. Preferably, it is used as a radiation-cooling coating material in building exterior walls, fabrics, and outdoor tents.

[0036] The present invention also provides a coating containing the above-mentioned rare earth-based stannate high-entropy ceramic material or prepared from the above-mentioned rare earth-based stannate high-entropy ceramic material.

[0037] The beneficial effects of this invention are:

[0038] This invention employs a solid-state synthesis method to prepare rare-earth-based stannate high-entropy ceramic materials. The preparation process is simple, and the synthesized rare-earth-based stannate high-entropy ceramic materials exhibit high purity and are suitable for large-scale applications. On the one hand, the rare-earth ions, due to their unique electronic layers, exhibit excellent optical properties, displaying high near-infrared reflectivity in the visible-near-infrared band. On the other hand, by applying the high-entropy "lattice distortion effect" and introducing rare-earth elements of different radii, the lattice distortion effect is further enhanced, resulting in high emissivity in the mid-infrared band for the rare-earth-based stannate high-entropy ceramic materials. Attached Figure Description

[0039] Figure 1 The rare earth-based stannate high-entropy ceramic material (Y) prepared in Example 1 of this invention is shown. 0.2 La 0.2 Nd 0.2 Eu 0.2 Gd 0.2 XRD pattern of 2Sn2O7.

[0040] Figure 2In Figures (a) and (b), the rare earth-based stannate high-entropy ceramic material (Y) prepared in Example 1 of this invention is shown. 0.2 La 0.2 Nd 0.2 Eu 0.2 Gd 0.2 Near-infrared and mid-infrared spectra of 2Sn2O7.

[0041] Figure 3 The rare earth-based stannate high-entropy ceramic material (Y) prepared in Example 1 of this invention is shown. 0.2 La 0.2 Nd 0.2 Eu 0.2 Gd 0.2 EDS plot of 2Sn2O7.

[0042] Figure 4 The rare earth-based stannate high-entropy ceramic material (Y) was prepared in Example 2 of this invention. 0.2 La 0.2 Sm 0.2 Eu 0.2 Lu 0.2 XRD pattern of 2Sn2O7.

[0043] Figure 5 In Figures (a) and (b), the rare-earth-based stannate high-entropy ceramic material (Y) prepared in Example 2 of this invention is shown. 0.2 La 0.2 Sm 0.2 Eu 0.2 Lu 0.2 Near-infrared and mid-infrared spectra of 2Sn2O7.

[0044] Figure 6 The rare earth-based stannate high-entropy ceramic material (Y) was prepared in Example 2 of this invention. 0.2 La 0.2 Sm 0.2 Eu 0.2 Lu 0.2 EDS plot of 2Sn2O7.

[0045] Figure 7 The rare earth-based stannate high-entropy ceramic material (Y) prepared in Example 3 of this invention is shown. 0.2 La 0.2 Gd 0.2 Yb 0.2 Lu 0.2 XRD pattern of 2Sn2O7.

[0046] Figure 8 In Figures (a) and (b), the rare earth-based stannate high-entropy ceramic material (Y) prepared in Example 3 of this invention is shown. 0.2 La 0.2Gd 0.2 Yb 0.2 Lu 0.2 Near-infrared and mid-infrared spectra of 2Sn2O7.

[0047] Figure 9 The rare earth-based stannate high-entropy ceramic material (Y) prepared in Example 3 of this invention is shown. 0.2 La 0.2 Gd 0.2 Yb 0.2 Lu 0.2 EDS plot of 2Sn2O7.

[0048] Figure 10 This is a process flow diagram for preparing the rare earth-based stannate high-entropy ceramic powder material of the present invention. Detailed Implementation

[0049] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0050] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0051] Example 1: A method for preparing rare earth-based stannate high-entropy ceramic powder material, the method comprising the following steps:

[0052] (1) Weigh 0.001 mol of Y2O3, 0.001 mol of La2O3, 0.001 mol of Nd2O3, 0.001 mol of Eu2O3, 0.001 mol of Gd2O3 and 0.01 mol of SnO2 respectively and place them in a 500 mL zirconia ball mill jar. Add 30 mL of ethanol and perform high-energy ball milling. Control the ball mill speed at 450 rpm and ball mill for 5 h (with a 1-minute break after every 4 minutes of operation during the ball milling process).

[0053] (2) Place the mixture after ball milling in step (1) in an oven and dry it at 65°C for 24 hours. Then sieve it through a 400-mesh standard sieve and press the powder into blocks. Set the pressure of the block press to 10MPa, press for 20s, and the diameter of the tablet mold to 15mm.

[0054] (3) Then, the sample obtained in step (2) is placed in a muffle furnace for calcination at a temperature of 1600℃, a heating rate of 10℃ / min, and a holding time of 6h to obtain rare earth-based stannate high-entropy ceramic material (Y). 0.2 La 0.2 Nd0.2 Eu 0.2 Gd 0.2 )2Sn2O7 green body;

[0055] (4) The rare earth-based stannate high-entropy ceramic material green body obtained in step (3) is crushed; high-energy ball milling is performed again, and the ball mill speed is controlled at 400 rpm for 10 h (with a 1-minute break after every 4 minutes of ball milling).

[0056] (5) The product obtained in step (4) is dried at 65℃ for 24 hours. After drying, it is sieved through a 400-mesh standard sieve and then pressed into tablets again. The pressure of the briquetting machine is set to 15MPa, and the pressing time is 20s. The diameter of the tableting mold is 10mm. The sample is placed in a muffle furnace for sintering. The sintering temperature is controlled at 1650℃, the heating rate is 5℃ / min, and the temperature is held for 5 hours. After crushing, the rare earth-based stannate high-entropy ceramic material (Y) can be obtained. 0.2 La 0.2 Nd 0.2 Eu 0.2 Gd 0.2 )2Sn2O7.

[0057] The rare earth-based stannate high-entropy ceramic material (Y) obtained in step (5) of this embodiment 0.2 La 0.2 Nd 0.2 Eu 0.2 Gd 0.2 XRD pattern of 2Sn2O7 as follows Figure 1 As shown, Figure 1 The results show that the rare earth-based stannate high-entropy ceramic material prepared in this embodiment has a pyrochlore structure, no extra impurity peaks appear, and the product has a complete crystal form.

[0058] Figure 2 The rare earth-based stannate high-entropy ceramic material (Y) prepared in this embodiment is shown in the figure. 0.2 La 0.2 Nd 0.2 Eu 0.2 Gd 0.2 Near-infrared (NIIR) of 2Sn2O7 Figure 2 (a) and mid-infrared ( Figure 2 (b) Band spectrum, from which it can be seen that: (Y 0.2 La 0.2 Nd 0.2 Eu 0.2 Gd 0.2 The average reflectance of 2Sn2O7 in the near-infrared band is 100.26%, (Y 0.2 La 0.2 Nd 0.2 Eu 0.2 Gd 0.2The average emissivity of 2Sn2O7 in the mid-infrared band is 91.38%.

[0059] The rare earth-based stannate high-entropy ceramic material (Y) prepared in this embodiment is... 0.2 La 0.2 Nd 0.2 Eu 0.2 Gd 0.2 The EDS elemental distribution diagram of 2Sn2O7 is shown below. Figure 3 As shown in the figure, the five rare earth ions are evenly distributed on the ceramic body, achieving uniform doping of rare earth metals.

[0060] Example 2

[0061] A method for preparing a rare-earth-based stannate high-entropy ceramic powder material, differing from Example 1 in that Sm2O3 is used instead of Nd2O3 and Lu2O3 is used instead of Gd2O3, includes the following steps:

[0062] (1) Weigh 0.001 mol of Y2O3, 0.001 mol of La2O3, 0.001 mol of Sm2O3, 0.001 mol of Eu2O3, 0.001 mol of Lu2O3 and 0.01 mol of SnO2 respectively and place them in a 500 mL zirconia ball mill jar. Add 30 mL of ethanol and perform high-energy ball milling. Control the ball mill speed at 450 rpm and ball mill for 5 h (with a 1-minute break after every 4 minutes of operation during the ball milling process).

[0063] (2) Place the mixture after ball milling in step (1) in an oven and dry it at 65°C for 24 hours. Then sieve it through a 400-mesh standard sieve and press the powder into blocks. Set the pressure of the block press to 10MPa, press for 20s, and the diameter of the tablet mold to 15mm.

[0064] (3) Then, the sample obtained in step (2) is placed in a muffle furnace for calcination at a temperature of 1600℃, a heating rate of 10℃ / min, and a holding time of 6h to obtain rare earth-based stannate high-entropy ceramic material (Y). 0.2 La 0.2 Sm 0.2 Eu 0.2 Lu 0.2 )2Sn2O7 green body;

[0065] (4) The rare earth-based stannate high-entropy ceramic material green body obtained in step (3) is crushed; high-energy ball milling is performed again, and the ball mill speed is controlled at 400 rpm for 10 hours (with a 1-minute break after every 4 minutes of ball milling).

[0066] (5) The product obtained in step (4) is dried at 65℃ for 24 hours. After drying, it is sieved through a 400-mesh standard sieve and then pressed into tablets again. The pressure of the briquetting machine is set to 15MPa, and the pressing time is 20s. The diameter of the tableting mold is 10mm. The sample is placed in a muffle furnace for sintering. The sintering temperature is controlled at 1650℃, the heating rate is 5℃ / min, and the temperature is held for 5 hours. After crushing, the rare earth-based stannate high-entropy ceramic material (Y) can be obtained. 0.2 La 0.2 Sm 0.2 Eu 0.2 Lu 0.2 )2Sn2O7.

[0067] The rare earth-based stannate high-entropy ceramic material (Y) prepared in Example 2 0.2 La 0.2 Sm 0.2 Eu 0.2 Lu 0.2 XRD pattern of 2Sn2O7 as follows Figure 4 As shown. Figure 4 The results show that the rare earth-based stannate high-entropy ceramic material prepared in this embodiment has a pyrochlore structure, no extra impurity peaks appear, and the product has a complete crystal form.

[0068] Figure 5 The rare earth-based stannate high-entropy ceramic material (Y) prepared in Example 2 is shown. 0.2 La 0.2 Sm 0.2 Eu 0.2 Lu 0.2 Near-infrared spectrum of 2Sn2O7 Figure 5 a) and mid-infrared spectra ( Figure 5 (b) from Figure 2 It can be seen that (Y) 0.2 La 0.2 Sm 0.2 Eu 0.2 Lu 0.2 The average reflectance of 2Sn2O7 in the near-infrared band is 98.90%, and the average emissivity in the mid-infrared band (8-13μm) is 93.07%.

[0069] The rare earth-based stannate high-entropy ceramic material (Y) prepared in Example 2 0.2 La 0.2 Sm 0.2 Eu 0.2 Lu 0.2 The EDS elemental distribution diagram of 2Sn2O7 is shown below. Figure 6 As shown, from Figure 6 It can be seen that the five rare earth ions are evenly distributed on the ceramic body, achieving uniform doping of rare earth metals.

[0070] Example 3

[0071] A method for preparing a rare-earth-based stannate high-entropy ceramic powder material, differing from Example 1 in that Yb₂O₃ is used instead of Nd₂O₃ and Lu₂O₃ is used instead of Eu₂O₃, includes the following steps:

[0072] (1) Weigh 0.001 mol of Y2O3, 0.001 mol of La2O3, 0.001 mol of Gd2O3, 0.001 mol of Yb2O3, 0.001 mol of Lu2O3 and 0.01 mol of SnO2 respectively and place them in a 500 mL zirconia ball mill jar. Add 30 mL of ethanol and perform high-energy ball milling. Control the ball mill speed at 450 rpm and ball mill for 5 h (with a 1-minute break after every 4 minutes of operation during the ball milling process).

[0073] (2) Place the mixture after ball milling in step (1) in an oven and dry it at 65°C for 24 hours. Then sieve it through a 400-mesh standard sieve and press the powder into blocks. Set the pressure of the block press to 10MPa, press for 20s, and the diameter of the tablet mold to 15mm.

[0074] (3) Then, the sample obtained in step (2) is placed in a muffle furnace for calcination at a temperature of 1600℃, a heating rate of 10℃ / min, and a holding time of 6h to obtain rare earth-based stannate high-entropy ceramic material (Y). 0.2 La 0.2 Gd 0.2 Yb 0.2 Lu 0.2 )2Sn2O7 green body;

[0075] (4) The rare earth-based stannate high-entropy ceramic material green body obtained in step (3) is crushed; high-energy ball milling is performed again, and the ball mill speed is controlled at 400 rpm for 10 hours (with a 1-minute break after every 4 minutes of ball milling).

[0076] (5) The product obtained in step (4) is dried at 65℃ for 24 hours. After drying, it is sieved through a 400-mesh standard sieve and then pressed into tablets again. The pressure of the briquetting machine is set to 15MPa, and the pressing time is 20s. The diameter of the tableting mold is 10mm. The sample is placed in a muffle furnace for sintering. The sintering temperature is controlled at 1650℃, the heating rate is 5℃ / min, and the temperature is held for 5 hours. After crushing, the rare earth-based stannate high-entropy ceramic material (Y) can be obtained. 0.2 La 0.2 Gd 0.2 Yb 0.2 Lu 0.2 )2Sn2O7.

[0077] The rare earth-based stannate high-entropy ceramic material (Y) prepared in Example 3 0.2 La 0.2 Gd 0.2 Yb 0.2 Lu 0.2 XRD pattern of 2Sn2O7 as follows Figure 7 As shown. Figure 7 The results show that the rare earth-based stannate high-entropy ceramic material prepared in this embodiment has a pyrochlore structure, no extra impurity peaks appear, and the product has a complete crystal form.

[0078] Figure 8 The rare earth-based stannate high-entropy ceramic material (Y) prepared in Example 3 is an example of this. 0.2 La 0.2 Gd 0.2 Yb 0.2 Lu 0.2 Near-infrared spectrum of 2Sn2O7 Figure 8 a) and mid-infrared spectra ( Figure 8 (b) from Figure 8 It can be seen that (Y) 0.2 La 0.2 Gd 0.2 Yb 0.2 Lu 0.2 The average reflectance of 2Sn2O7 in the near-infrared band is 104.06%, and the average emissivity in the mid-infrared band (8-13μm) is 95.41%.

[0079] The rare earth-based stannate high-entropy ceramic material (Y) prepared in Example 3 0.2 La 0.2 Gd 0.2 Yb 0.2 Lu 0.2 The EDS elemental distribution diagram of 2Sn2O7 is shown below. Figure 9 As shown, from Figure 9 It can be seen that the five rare earth ions are evenly distributed on the ceramic body, achieving uniform doping of rare earth metals.

[0080] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rare-earth-based stannate high-entropy ceramic material, characterized in that, The ceramic material is (Y 0.2 La 0.2 Nd 0.2 Eu 0.2 Gd 0.2 )2Sn2O7, (Y 0.2 La 0.2 Sm 0.2 Eu 0.2 Lu 0.2 )2Sn2O7, or (Y 0.2 La 0.2 Gd 0.2 Yb 0.2 Lu 0.2 )2Sn2O7. The rare-earth-based stannate high-entropy ceramic material has an average reflectance of 90-105% in the near-infrared band; The rare earth-based stannate high-entropy ceramic material has an average emissivity of 90-100% in the infrared band of 8-13 μm in the atmospheric window.

2. The rare-earth-based stannate high-entropy ceramic material as described in claim 1, characterized in that, The rare earth-based stannate high-entropy ceramic material has a pyrochlore structure.

3. The rare-earth-based stannate high-entropy ceramic material as described in claim 1, characterized in that, The rare-earth-based stannate high-entropy ceramic material has an average reflectance of 95-105% in the near-infrared band. And / or, the rare earth-based stannate high-entropy ceramic material has an average emissivity of 91-96% in the infrared band of 8-13 μm in the atmospheric window.

4. The method for preparing the rare earth-based stannate high-entropy ceramic material according to any one of claims 1-3, characterized in that, The method includes the following steps: mixing RE source and Sn source, and preparing rare earth-based stannate high-entropy ceramic material by solid-state synthesis; Among them, the RE sources are five types: yttrium oxide (Y2O3), lanthanum oxide (La2O3), neodymium oxide (Nd2O3), europium oxide (Eu2O3), and gadolinium oxide (Gd2O3); Alternatively, the RE source could be one of five types: yttrium oxide (Y2O3), lanthanum oxide (La2O3), samarium oxide (Sm2O3), europium oxide (Eu2O3), and lutetium oxide (Lu2O3). Alternatively, the RE source may be one of five types: yttrium oxide (Y2O3), lanthanum oxide (La2O3), gadolinium oxide (Gd2O3), ytterbium oxide (Yb2O3), and lutetium oxide (Lu2O3).

5. The preparation method according to claim 4, characterized in that, The Sn source is tin dioxide (SnO2); And / or, the molar ratio of RE source to Sn source is 1:(0.5-5).

6. The preparation method according to claim 4, characterized in that, The calcination temperature of the solid-phase synthesis method is 1500-1650 ℃; the calcination time of the solid-phase synthesis method is 2-15 h.

7. The preparation method according to claim 6, characterized in that, The solid-phase synthesis method involves multiple calcinations, with the calcination temperatures being the same or different, and each calcination is independent of the others, ranging from 1500 to 1650 ℃; the calcination times are also the same or different, and each calcination is independent of the others, ranging from 2 to 15 hours.

8. The preparation method according to any one of claims 4-7, characterized in that, Includes the following steps: (1) Mix the RE source and Sn source and ball mill them with ethanol as the medium; (2) The ball-milled slurry is dried, sieved, and pressed into tablets to obtain the embryo; (3) Calcine and heat-keep the green body obtained in step (2) to obtain a raw green body; (4) After crushing the green body obtained in step (3), the powder is ball-milled with ethanol as the medium, and then dried, sieved and pressed into tablets to obtain the green body; (5) The blank obtained in step (4) is calcined again, kept warm, and crushed to obtain the target product, rare earth-based stannate high-entropy ceramic material.

9. The application of the rare earth-based stannate high-entropy ceramic material according to any one of claims 1-3 or the rare earth-based stannate high-entropy ceramic material prepared by the preparation method according to any one of claims 4-7 in building exterior walls, fabrics, and outdoor tents.

10. The application as described in claim 9, characterized in that, The rare earth-based stannate high-entropy ceramic material is used as a radiation cooling coating material in building exterior walls, fabrics, and outdoor tents.

11. A coating, characterized in that, The coating comprises the rare earth-based stannate high-entropy ceramic material according to any one of claims 1-3 or the rare earth-based stannate high-entropy ceramic material prepared by the preparation method according to any one of claims 4-7, or prepared by the rare earth-based stannate high-entropy ceramic material according to any one of claims 1-3 or the rare earth-based stannate high-entropy ceramic material prepared by the preparation method according to any one of claims 4-7.

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