Zirconate ceramic with electromagnetic wave regulation characteristics and preparation method thereof

Abstract

This invention relates to a zirconate ceramic with electromagnetic wave modulation properties. The zirconate ceramic has the general chemical formula A₂Zr₂O₇, where the A-site is composed of three or four metallic elements, including La, selected from La, Pr, Co, Cu, Fe, Ni, and Cr; and the molar percentage of each element at the A-site is between 20% and 50%. The zirconate ceramic has a single pyrochlore structure with space group Fd⁻³m; its average light absorptivity in the 0.3–2.5 μm wavelength range is greater than 0.92, and its average infrared emissivity in the 0.78–25 μm wavelength range is greater than 0.90. This invention also discloses a method for preparing this zirconate ceramic. By introducing transition metal elements at the A-site, this invention provides the possibility of optimizing electromagnetic wave modulation performance. The obtained zirconate ceramic has crucial application value in fields such as solar thermal utilization, aerospace thermal protection, industrial high-temperature energy saving, infrared stealth, and radiative cooling.

Description

Technical Field

[0001] This invention relates to the field of functional ceramics technology, and in particular to a zirconate ceramic with electromagnetic wave modulation characteristics and its preparation method. Background Technology

[0002] Electromagnetic wave modulating materials, through their specific absorption, emission, and reflection properties, can efficiently manage and convert energy forms such as light and heat, possessing crucial application value in fields such as solar thermal utilization, aerospace thermal protection, industrial high-temperature energy saving, infrared stealth, and radiative cooling. The 0.3–2.5 μm band covers the visible light (0.3–0.78 μm) and near-infrared (0.78–2.5 μm) regions where solar radiation energy is most concentrated; high absorption in this band is a prerequisite for efficient photothermal conversion. Conversely, the 0.78–25 μm band covers the main region of thermal radiation from objects; high emission in this band is key to efficient radiative heat dissipation or infrared stealth. Therefore, developing a material that possesses excellent performance in both of these broad spectral bands is crucial for achieving effective thermal management technology.

[0003] Currently, the most studied electromagnetic wave modulation materials mainly include spinel, perovskite, and silicon carbide. CN113443654B discloses a rare-earth-doped spinel material with electromagnetic wave modulation function, which has a solar absorptivity ≥0.87 in the 0.3~2.5μm band and a normal infrared emissivity ≥0.92 in the 2~22μm band, and exhibits certain crystal structure stability at 1000℃. However, spinel oxides are prone to elemental segregation and structural evolution at higher temperatures, leading to performance degradation (Mater. Today Phys. 2024. 42:101363), which limits its application in high-temperature fields. CN113248258B discloses a silicon carbide-based multiphase ceramic material with high spectral selectivity, which has high solar spectral selectivity and oxidation resistance, but its main focus is on the solar radiation band, and its modulation ability in the broad spectrum, especially the mid- and far-infrared bands, is insufficient, limiting its application areas.

[0004] Zirconate ceramics (A₂Zr₂O₇) have attracted widespread attention due to their excellent high-temperature phase stability, lower thermal conductivity, and high oxygen vacancy concentration. Their typical crystal structures are defective fluorite and pyrochlore structures. The pyrochlore structure can be considered a fluorite-derived structure lacking 1 / 8 of its anion lattice sites, and its A-site ions possess high designability. Therefore, by introducing various rare earth or transition metal elements into the A-site for composite formation and controlling their elemental types and molar ratios, lattice distortion and oxygen vacancy concentration can be effectively adjusted, providing new opportunities for achieving broadband, high-performance electromagnetic wave modulation. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a zirconate ceramic with good performance and electromagnetic wave modulation characteristics.

[0006] Another technical problem to be solved by the present invention is to provide a method for preparing the zirconate ceramic with electromagnetic wave modulation characteristics.

[0007] To address the aforementioned problems, the present invention provides a zirconate ceramic with electromagnetic wave modulation characteristics, characterized in that: the general chemical formula of the zirconate ceramic is A2Zr2O7, wherein the A-site is composed of three or four metallic elements, including La, selected from La, Pr, Co, Cu, Fe, Ni, and Cr; and the molar percentage of each element in the A-site is between 20% and 50%; the zirconate ceramic has a single pyrochlore structure with space group Fd-3m; its average light absorptivity in the 0.3~2.5μm band is greater than 0.92, and its average infrared emissivity in the 0.78~25μm band is greater than 0.90.

[0008] The zirconate ceramic exhibits a performance degradation rate of less than 5% after being heat-stabilized at 1300℃ for 500 hours.

[0009] The method for preparing a zirconate ceramic with electromagnetic wave modulation characteristics as described above includes the following steps:

[0010] (1) Weigh the raw materials ZrO2 and AO according to the stoichiometric ratio. x AO x Composed of three or four oxides, including La2O3, AO x Selected from La2O3 and Pr6O 11 , Co3O4, CuO, Fe2O3, NiO, Cr2O3;

[0011] (2) After mixing the raw materials, put them into a planetary ball mill for wet ball milling, and after drying and sieving, a uniformly mixed precursor powder is obtained.

[0012] (3) The precursor powder is calcined at high temperature in air, and after cooling and grinding, zirconate powder material is obtained.

[0013] (4) After sieving the zirconate powder material, it is first pressed into sheets, and then calcined at high temperature and cooled to obtain zirconate ceramics.

[0014] The conditions for wet ball milling in step (2) are as follows: the ball milling medium is zirconia balls, the ball milling solvent is anhydrous ethanol, the ball milling speed is 200~400 r / min, the ball milling time is 8~12 hours, and the mass ratio of balls, material and solvent is (0.8~1.2):1:(1~2).

[0015] The drying conditions in step (2) refer to using a constant temperature oven, with a drying temperature of 80~100℃ and a drying time of 12~24 hours.

[0016] The conditions for high-temperature calcination in step (3) refer to using a high-temperature box furnace, with a calcination temperature of 1000~1200℃, a heating rate of 2~5℃ / min, and a calcination time of 6~8 hours.

[0017] The conditions for tableting in step (4) refer to using a powder tableting machine, with a pressure of 5~10MPa and a tableting time of 5~10min.

[0018] The conditions for high-temperature secondary calcination in step (4) are as follows: a high-temperature box furnace is used, the calcination temperature is 1200~1300℃, the programmed temperature rise is: rise to 800℃ at a heating rate of 5~10℃ / min, then rise to the target temperature at a heating rate of 2~5℃ / min, and the calcination time is 6~8 hours.

[0019] In steps (3) and (4), the cooling method is continuous cooling or isothermal cooling, and the cooling medium is air.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The zirconate system selected in this invention possesses advantages such as strong chemical inertness, high temperature resistance, and good thermal shock resistance. By introducing three or four specific elements (including La) at the A-site of A₂Zr₂O₇ and controlling the non-equimolar ratio, the formation and stability of a single pyrochlore phase (space group Fd-3m) are ensured. Compared with traditional ceramics, A₂Zr₂O₇ allows for the design of different cation-doped combinations at the A-site, offering greater design flexibility. Simultaneously, due to the differences in ionic radius and electronegativity between A-site elements (such as rare earth elements La and Pr and transition metals Co, Fe, Ni, etc.), lattice distortion occurs, allowing for the control of oxygen vacancy concentration (exceeding the inherent 1 / 8 vacancy of the pyrochlore structure) and cation vacancies, providing the possibility for optimizing electromagnetic wave modulation performance.

[0022] 2. This invention, through unique composition and structural design, endows the material with unique electromagnetic wave modulation characteristics. It efficiently manages and converts energy forms such as light and heat across a wide wavelength range through specific absorption, emission, and reflection. Due to the interaction between the d-orbital electrons of transition metal elements (such as Co, Fe, Cr, etc.) introduced at the A-site and the f-orbital electrons of rare earth elements (such as La, Pr), abundant electronic transitions (inter-band and intra-band transitions) are generated, significantly narrowing the band gap and widening the range of electronic transition energy levels, thus achieving an absorption rate >0.92 in the 0.3~2.5μm band. Simultaneously, the resulting lattice distortion and oxygen vacancies enhance the lattice asymmetry, and lattice vibration modes (phonons) are more effectively converted into photons for radiation, resulting in extremely high emissivity (>0.90) across the entire mid- and far-infrared band.

[0023] 3. The zirconate ceramics in this invention exhibit excellent high-temperature reliability. The stable pyrochlore structure makes it less prone to phase transformation or decomposition at high temperatures, ensuring long-term performance stability.

[0024] 4. This invention employs a combination of mechanical wet milling and high-temperature calcination to prepare zirconate ceramics. This method offers advantages such as simple preparation techniques, high repeatability, high production efficiency, and suitability for automated operation. The resulting zirconate ceramics exhibit a single phase, high purity, and uniform elemental distribution, demonstrating potential applications in radiant heat management for large-scale energy equipment, aero-engines, gas turbines, electronic devices, and power plant boilers. Attached Figure Description

[0025] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0026] Figure 1 This is Embodiment 1 of the present invention (La) 0.5 Co 0.25 Cu 0.25 Crystal structure diagram of pyrochlore in 2Zr2O7.

[0027] Figure 2 This is Embodiment 1 of the present invention (La) 0.5 Co 0.25 Cu 0.25 XRD pattern of 2Zr2O7.

[0028] Figure 3 This is Embodiment 2 of the present invention (La) 0.4 Pr 0.3 Cu 0.3 XRD pattern of 2Zr2O7.

[0029] Figure 4 This is embodiment 3 of the present invention (La) 0.4 Pr 0.2 Co0.2 Cr 0.2 XRD pattern of 2Zr2O7.

[0030] Figure 5 The light absorption spectrum of the zirconate ceramic prepared in Example 4 of this invention is shown in the 0.3~2.5μm wavelength range.

[0031] Figure 6 The infrared emission spectrum of the zirconate ceramic prepared in Example 4 of this invention is shown in the 0.78~25μm wavelength range. Detailed Implementation

[0032] A zirconate ceramic with electromagnetic wave modulation properties, the general chemical formula of which is A2Zr2O7, wherein the A site is composed of three or four metal elements including La, selected from La, Pr, Co, Cu, Fe, Ni, and Cr; and the molar percentage of each element in the A site is between 20% and 50%; the zirconate ceramic has a single pyrochlore structure with space group Fd-3m; its average light absorptivity in the 0.3-2.5 μm band is greater than 0.92, and its average infrared emissivity in the 0.78-25 μm band is greater than 0.90.

[0033] Among them, the zirconate ceramic exhibits good thermal stability, with a performance degradation rate of less than 5% after being heat-stabilized at 1300℃ for 500 hours.

[0034] A method for preparing zirconate ceramics with electromagnetic wave modulation properties includes the following steps:

[0035] (1) Weigh the raw materials ZrO2 and AO according to the stoichiometric ratio. x AO x Composed of three or four oxides, including La2O3, AO x Selected from La2O3 and Pr6O 11 , Co3O4, CuO, Fe2O3, NiO, Cr2O3.

[0036] (2) After mixing all the raw materials, put them into a planetary ball mill for wet ball milling. The ball milling media is zirconia balls, the ball milling solvent is anhydrous ethanol, the ball milling speed is 200~400 r / min, the ball milling time is 8~12 hours, and the mass ratio (g / g) of balls, materials and solvent is (0.8~1.2):1:(1~2). Then put them into a constant temperature oven, dry them at 80~100℃ for 12~24 hours, and pass them through a fine sieve to obtain a uniformly mixed precursor powder.

[0037] (3) The precursor powder is placed in a high-temperature box furnace and calcined at high temperature in an air atmosphere. The calcination temperature is 1000~1200℃, the heating rate is 2~5℃ / min, and the calcination time is 6~8 hours. Then, continuous cooling or isothermal cooling is used, and the cooling medium is air. After grinding, zirconate powder material is obtained.

[0038] (4) After sieving the zirconate powder material, it is first pressed into tablets using a powder tablet press at a pressure of 5-10 MPa for 5-10 min. Then, it is subjected to high-temperature secondary calcination in a high-temperature box furnace at a temperature of 1200-1300℃. The programmed temperature rise is as follows: rise to 800℃ at a rate of 5-10℃ / min, and then rise to the target temperature at a rate of 2-5℃ / min for 6-8 hours. Then, continuous cooling or isothermal cooling is used with air as the cooling medium to obtain zirconate ceramics.

[0039] Example 1 (La) 0.5 Co 0.25 Cu 0.25 The preparation method of 2Zr2O7 zirconate ceramics includes the following steps:

[0040] (1) Weigh out 8.153g La2O3, 2.008g Co3O4, 2g CuO, and 12.3g ZrO2.

[0041] (2) The ball milling speed is 300 r / min, the ball milling time is 10 hours, and the mass ratio (g / g) of balls, material and solvent is 0.8:1:1; then it is placed in a constant temperature oven and dried at 80℃ for 16 hours; after passing through a fine sieve, a uniformly mixed precursor powder is obtained.

[0042] (3) The precursor powder was placed in a high-temperature box furnace and calcined in an air atmosphere at a temperature of 1000℃, a heating rate of 5℃ / min, and a calcination time of 8 hours; then continuous cooling was used, with air as the cooling medium; after grinding, (La) was obtained. 0.5 Co 0.25 Cu 0.25 )2Zr2O7 zirconate powder material.

[0043] (4) After sieving, the zirconate powder material is compressed into tablets using a powder tablet press at a pressure of 5 MPa for 10 minutes. Subsequently, it undergoes a second high-temperature calcination in a high-temperature box furnace at 1200℃. The programmed temperature increase is: 5℃ / min to 800℃, then 2℃ / min to 1200℃, for a total calcination time of 6 hours. Finally, continuous cooling is performed using air as the cooling medium to obtain (La). 0.5 Co 0.25 Cu 0.25 )2Zr2O7 zirconate ceramics.

[0044] Regarding the obtained (La) 0.5 Co 0.25 Cu 0.25 XRD analysis was performed on 2Zr₂O₇ zirconate ceramics. An EMPYREAN X-ray single-crystal diffractometer manufactured by Panaco (Netherlands) was used to determine the crystal structure of the high-entropy ceramics. The results are as follows: Figures 1-2 As shown in the figure, the spectral line matches very well with the spectral line with pyrochlore structure (PDF#17-0450) in the ICDD database, indicating that the zirconate ceramic prepared in this embodiment has a simple structure.

[0045] Example 2 (La) 0.4 Pr 0.3 Cu 0.3 The preparation method of 2Zr2O7 zirconate ceramics includes the following steps:

[0046] (1) Weigh out 6.52g of raw materials La2O3 and 5.1072g of Pr6O3. 11 2.4g CuO, 12.3g ZrO2.

[0047] (2) After mixing all the raw materials, put them into a planetary ball mill for wet ball milling. The ball milling media is zirconia balls, the ball milling solvent is anhydrous ethanol, the ball milling speed is 200 r / min, the ball milling time is 12 hours, and the mass ratio (g / g) of balls, materials and solvent is 1:1:2. Then put them into a constant temperature oven and dry them at 100℃ for 12 hours. After passing through a fine sieve, a uniformly mixed precursor powder is obtained.

[0048] (3) The precursor powder was placed in a high-temperature box furnace and calcined in an air atmosphere at a temperature of 1050℃, a heating rate of 2℃ / min, and a calcination time of 6 hours; subsequently, continuous cold cooling was used, with air as the cooling medium; after grinding, (La) was obtained. 0.4 Pr 0.3 Cu 0.3 )2Zr2O7 zirconate powder material.

[0049] (4) After sieving, the zirconate powder was compressed into tablets using a powder tablet press at a pressure of 8 MPa for 5 minutes. Subsequently, it underwent a second high-temperature calcination in a high-temperature box furnace at 1300℃. The programmed temperature rise was: increasing to 800℃ at a rate of 10℃ / min, then increasing to the target temperature at a rate of 2℃ / min for 7 hours. Isothermal cooling was then performed using air as the cooling medium to obtain (La). 0.4 Pr 0.3 Cu 0.3 )2Zr2O7 zirconate ceramics.

[0050] Regarding the obtained (La) 0.4 Pr 0.3 Cu 0.3 XRD analysis was performed on 2Zr₂O₇ zirconate ceramics. An EMPYREAN X-ray single-crystal diffractometer manufactured by Panaco (Netherlands) was used to determine the crystal structure of the high-entropy ceramics. The results are as follows: Figure 3 As shown in the figure, the spectral line matches very well with the spectral line with pyrochlore structure (PDF#17-0450) in the ICDD database, indicating that the zirconate ceramic prepared in this embodiment has a simple structure.

[0051] Example 3 (La) 0.4 Pr 0.2 Co 0.2 Cr 0.2 The preparation method of 2Zr2O7 zirconate ceramics includes the following steps:

[0052] (1) Weigh out 6.52g of raw materials La2O3 and 3.4048g of Pr6O3. 11 , 1.607g Co3O4, 1.52g Cr2O3, 12.3gZrO2.

[0053] (2) After mixing all the raw materials, put them into a planetary ball mill for wet ball milling. The ball milling media is zirconia balls, the ball milling solvent is anhydrous ethanol, the ball milling speed is 400 r / min, the ball milling time is 8 hours, and the mass ratio (g / g) of balls, materials and solvent is 1.2:1:1.5. Then put them into a constant temperature oven and dry them at 90℃ for 12 hours. After passing through a fine sieve, a uniformly mixed precursor powder is obtained.

[0054] (3) The precursor powder was placed in a high-temperature box furnace and calcined in air at a temperature of 1200℃, a heating rate of 2℃ / min, and a calcination time of 6 hours; subsequently, continuous cold cooling was used with air as the cooling medium; after grinding, (La) was obtained. 0.4 Pr 0.2 Co 0.2 Cr 0.2 )2Zr2O7 zirconate powder material.

[0055] (4) After sieving, the zirconate powder was compressed into tablets using a powder tablet press at a pressure of 10 MPa for 5 minutes. Subsequently, it underwent a second high-temperature calcination in a high-temperature box furnace at 1280℃. The programmed temperature rise was: increasing to 800℃ at a rate of 7℃ / min, then increasing to the target temperature at a rate of 5℃ / min for 6 hours. Isothermal cooling was then performed using air as the cooling medium to obtain (La). 0.4 Pr 0.2 Co 0.2 Cr 0.2)2Zr2O7 zirconate ceramics.

[0056] Regarding the obtained (La) 0.4 Pr 0.2 Co 0.2 Cr 0.2 XRD analysis was performed on 2Zr₂O₇ zirconate ceramics. An EMPYREAN X-ray single-crystal diffractometer manufactured by Panaco (Netherlands) was used to determine the crystal structure of the high-entropy ceramics. The results are as follows: Figure 4 As shown in the figure, the spectral line matches very well with the spectral line with pyrochlore structure (PDF#17-0450) in the ICDD database, indicating that the zirconate ceramic prepared in this embodiment has a simple structure.

[0057] Example 4 (La) 0.3 Co 0.2 Fe 0.3 Ni 0.2 The preparation method of 2Zr2O7 zirconate ceramics includes the following steps:

[0058] (1) Weigh out the following raw materials: 3.26g La2O3, 1.607g Co3O4, 2.4g Fe2O3, 1.49g NiO, and 12.3g ZrO2.

[0059] (2) After mixing all the raw materials, put them into a planetary ball mill for wet ball milling. The ball milling media is zirconia balls, the ball milling solvent is anhydrous ethanol, the ball milling speed is 200 r / min, the ball milling time is 10 hours, and the mass ratio (g / g) of balls, materials and solvent is 1.2:1:2. Then put them into a constant temperature oven and dry them at 80℃ for 24 hours. After passing through a fine sieve, a uniformly mixed precursor powder is obtained.

[0060] (3) The precursor powder was placed in a high-temperature box furnace and calcined in air at a temperature of 1100℃, a heating rate of 3℃ / min, and a calcination time of 7 hours; then isothermal cooling was used, with air as the cooling medium; after grinding, (La) was obtained. 0.3 Co 0.2 Fe 0.3 Ni 0.2 )2Zr2O7 zirconate powder material.

[0061] (4) After sieving, the zirconate powder material is compressed into tablets using a powder tableting machine at a pressure of 5 MPa for 8 minutes. Subsequently, it undergoes a high-temperature secondary calcination in a high-temperature box furnace at 1300℃. The programmed temperature rise is as follows: increasing to 800℃ at a rate of 10℃ / min, then increasing to the target temperature at a rate of 3℃ / min for 8 hours. Continuous cooling is then employed using air as the cooling medium to obtain (La). 0.3 Co0.2 Fe 0.3 Ni 0.2 )2Zr2O7 zirconate ceramics.

[0062] Regarding the obtained (La) 0.3 Co 0.2 Fe 0.3 Ni 0.2 Infrared emissivity tests were conducted on 2Zr2O7 zirconate ceramics. A Lambda 950 UV / Vis / NIR spectrophotometer (equipped with a 150mm integrating sphere) manufactured by PerkinElmer, USA, was used to evaluate the infrared radiation performance of defective fluorite-type high-entropy cerate ceramics. The light absorptivity in the 0.3~2.5μm band and the infrared emissivity in the 0.78~25μm band were measured. Then, the infrared emissivity of the corresponding bands was calculated according to formulas (1)~(2).

[0063]

[0064] Where: α(θ, λ) is the absorptivity of the material at the solar incidence angle θ and wavelength λ; R(θ,λ) is the reflectivity of the material at the solar incidence angle θ and wavelength λ; I S (λ) is the spectral radiation intensity of the sun when the atmospheric mass is AM 1.5; ε(λ,T) is the emissivity of the material at wavelength λ and temperature T; I b (λ,T) is the thermal radiation intensity of a blackbody material at temperature T.

[0065] The results are as follows Figure 5 and 6 As shown. Calculations show that the light absorptivity is 0.93 in the 0.3~2.5μm band and the infrared emissivity is 0.91 in the 0.78~25μm band.

Claims

1. A zirconate ceramic with electromagnetic wave modulation characteristics, characterized in that: The general chemical formula of the zirconate ceramic is A2Zr2O7, wherein the A site is composed of three or four metal elements including La, and the metal elements are selected from La, Pr, Co, Cu, Fe, Ni and Cr; and the molar percentage of each element in the A site is between 20 and 50%; the zirconate ceramic has a single pyrochlore structure and the space group is Fd-3m. Its average light absorptivity in the 0.3~2.5μm band is greater than 0.92, and its average infrared emissivity in the 0.78~25μm band is greater than 0.

90.

2. The zirconate ceramic with electromagnetic wave modulation characteristics as described in claim 1, characterized in that: The zirconate ceramic exhibits a performance degradation rate of less than 5% after being heat-stabilized at 1300℃ for 500 hours.

3. A method for preparing a zirconate ceramic with electromagnetic wave modulation characteristics as described in claim 1 or 2, comprising the following steps: (1) The raw materials Zr02 and AO are weighed according to the stoichiometric ratio x wherein AO x consists of three or four oxides including La203, AO x is selected from La203, Pr606 11 , Co304, CuO, Fe203, NiO, Cr203; (2) After mixing the raw materials, put them into a planetary ball mill for wet ball milling, and after drying and sieving, a uniformly mixed precursor powder is obtained. (3) The precursor powder is calcined at high temperature in air, and after cooling and grinding, zirconate powder material is obtained. (4) After sieving the zirconate powder material, it is first pressed into sheets, and then calcined at high temperature and cooled to obtain zirconate ceramics.

4. The method for preparing zirconate ceramics with electromagnetic wave modulation characteristics as described in claim 3, characterized in that: The conditions for wet ball milling in step (2) are as follows: the ball milling medium is zirconia balls, the ball milling solvent is anhydrous ethanol, the ball milling speed is 200~400 r / min, the ball milling time is 8~12 hours, and the mass ratio of balls, material and solvent is (0.8~1.2):1:(1~2).

5. The method for preparing zirconate ceramics with electromagnetic wave modulation characteristics as described in claim 3, characterized in that: The drying conditions in step (2) refer to using a constant temperature oven, with a drying temperature of 80~100℃ and a drying time of 12~24 hours.

6. The method for preparing a zirconate ceramic with electromagnetic wave modulation characteristics as described in claim 3, characterized in that: The conditions for high-temperature calcination in step (3) refer to using a high-temperature box furnace, with a calcination temperature of 1000~1200℃, a heating rate of 2~5℃ / min, and a calcination time of 6~8 hours.

7. The method for preparing zirconate ceramics with electromagnetic wave modulation characteristics as described in claim 3, characterized in that: The conditions for tableting in step (4) refer to using a powder tableting machine, with a pressure of 5~10MPa and a tableting time of 5~10min.

8. The method for preparing zirconate ceramics with electromagnetic wave modulation characteristics as described in claim 3, characterized in that: The conditions for high-temperature secondary calcination in step (4) are as follows: a high-temperature box furnace is used, the calcination temperature is 1200~1300℃, the programmed temperature rise is: rise to 800℃ at a heating rate of 5~10℃ / min, then rise to the target temperature at a heating rate of 2~5℃ / min, and the calcination time is 6~8 hours.

9. The method for preparing a zirconate ceramic with electromagnetic wave modulation characteristics as described in claim 3, characterized in that: In steps (3) and (4), the cooling method is continuous cooling or isothermal cooling, and the cooling medium is air.

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