A multiphase ceramic and a method for preparing and using the same

Abstract

The present disclosure relates to a complex-phase ceramic and a preparation method and application thereof, the electrical performance of the ceramic single crystal boundary is improved by introducing yttrium element and complex phase, and then the electrical performance of the entire ceramic system is improved; the prepared yttrium element doped calcium copper titanate and strontium copper titanate complex phase ceramic system has excellent breakdown field strength and giant dielectric performance, and can improve the performance of capacitor energy storage elements, memory functional devices, multilayer ceramic capacitors and other functional devices.

Description

Technical Field

[0001] This disclosure relates to the field of electrical materials technology, and in particular to a multiphase ceramic, its preparation method, and its application. Background Technology

[0002] Due to the rapid development of the new energy industry, information technology, and artificial intelligence, the demand for high energy density, high integration, and multifunctionality has become a key research objective in the field of electrical ceramics. Calcium copper titanate ceramics (CaCu3Ti4O) 12 CCTO) is available over a fairly wide frequency and temperature range (10–10). 6 It has a stable giant dielectric constant (>10) within the range of Hz, 100–400 K. 3 Calcium copper titanate (CTi) is considered a lead-free material with broad application prospects, suitable for use in high energy density and multilayer ceramic capacitors. Furthermore, CTi exhibits significant nonlinear current-voltage characteristics, making it a potential novel energy storage-overvoltage protector material. It could play a crucial role in active applications such as protecting equipment from voltage transients and noise, energy storage devices, and high-voltage capacitive devices.

[0003] However, the relatively low breakdown field strength and high dielectric loss are obstacles that need to be overcome before calcium copper titanate ceramics can be practically applied. Typically, the breakdown field strength of calcium copper titanate ceramics is between 1 and 2 kV cm⁻¹. -1 This severely limits its application in energy storage and overvoltage protection. Furthermore, dielectric losses exceeding 0.1 ohms will generate significant heat, drastically reducing its energy efficiency and leading to device failure. Summary of the Invention

[0004] To address at least one of the aforementioned technical problems, this disclosure provides a multiphase ceramic, its preparation method, and its application. By introducing yttrium and the multiphase ceramic, the electrical properties of the ceramic single crystal boundaries are jointly enhanced, thereby improving the electrical properties of the entire ceramic system.

[0005] In one aspect, this disclosure provides a method for preparing multiphase ceramics, comprising: mixing rare earth element-doped copper calcium titanate ceramic powder with copper strontium titanate ceramic powder, granulating, forming, debinding, and sintering to obtain multiphase ceramics.

[0006] In some embodiments of this disclosure, the molar ratio of rare earth element-doped calcium copper titanate ceramic powder to strontium copper titanate ceramic powder is 1:1; and / or, the rare earth element doping amount in the calcium copper titanate ceramic powder is 1.44% to 8.45%, for example, the rare earth element doping amount in the calcium copper titanate ceramic powder can be any value among 2.45%, 3.68%, 4.86%, 5.69%, 6.63%, 7.98%, etc.

[0007] In some embodiments of this disclosure, the heating procedure for debinding is as follows: the temperature is increased to 350-450°C (e.g., any one of 362°C, 386°C, 406°C, 428°C, 448°C) at a rate of 40-60°C / h (e.g., any one of 42°C / h, 47°C / h, 51°C / h, 56°C / h, 59°C / h, etc.), held for 4-6 hours (e.g., any one of 4.2 hours, 4.6 hours, 4.8 hours, 5.2 hours, 5.6 hours, 5.9 hours, etc.), and then increased again at a rate of 40-60°C / h (e.g., any one of 41°C / h, 46°C / h, 49°C / h, etc.). The temperature is lowered to room temperature at a rate of 53℃ / h, 58℃ / h, etc.; and / or the heating program for sintering is as follows: the temperature is raised to 990-1010℃ (e.g., any temperature value selected from 996℃, 999℃, 1001℃, 1006℃, 1009℃, etc.) at a rate of 150-200℃ / h (e.g., any temperature value selected from 151℃ / h, 176℃ / h, 189℃ / h, 193℃ / h, 198℃ / h, etc.), held for 4-8 hours (e.g., any holding time selected from 4.3 hours, 4.9 hours, 5.6 hours, 6.2 hours, 7.1 hours, 7.9 hours, etc.), and then naturally cooled to room temperature.

[0008] In some embodiments of this disclosure, the rare earth element-doped copper calcium titanate ceramic powder is yttrium element-doped copper calcium titanate ceramic powder.

[0009] In some embodiments of this disclosure, the method for preparing yttrium-doped copper-calcium titanate ceramic powder includes: mixing a yttrium-containing compound, a titanium-containing compound, a copper-containing compound, and a calcium-containing compound, and calcining (I) to prepare yttrium-doped copper-calcium titanate ceramic powder; and / or, the method for preparing copper-strontium titanate ceramic powder includes: mixing a titanium-containing compound, a copper-containing compound, and a strontium-containing compound, and calcining (II) to prepare copper-strontium titanate ceramic powder.

[0010] In some embodiments of this disclosure, the temperature of calcination I is 900–950°C (e.g., any one of 906°C, 919°C, 926°C, 938°C, 949°C, etc.), and the time is 8–10 h (e.g., any one of 8.3 h, 8.8 h, 9.1 h, 9.4 h, 9.6 h, 9.9 h, etc.); and / or, the temperature of calcination II is 850–900°C (e.g., any one of 856°C, 869°C, 873°C, 886°C, 898°C, etc.), and the time is 6–8 h (e.g., any one of 6.3 h, 6.8 h, 7.1 h, 7.4 h, 7.6 h, 7.9 h, etc.).

[0011] In some embodiments of this disclosure, the molar ratio of the yttrium-containing compound, the calcium-containing compound, the copper-containing compound, and the titanium-containing compound is (0.1–0.6):(0.30–2.55):9:12, for example, the molar ratio is selected from any one of 0.16:0.58:9:12, 0.28:0.98:9:12, 0.36:1.28:9:12, 0.48:1.58:9:12, 0.52:1.98:9:12, 0.58:2.52:9:12, etc.; and / or, the molar ratio of the strontium-containing compound, the copper-containing compound, and the titanium-containing compound is 1:3:4.

[0012] In some embodiments of this disclosure, the yttrium-containing compound is yttrium oxide, the titanium-containing compound is titanium dioxide, the copper-containing compound is copper oxide, the calcium-containing compound is calcium carbonate, and the strontium-containing compound is strontium carbonate.

[0013] In another aspect, this disclosure provides a multiphase ceramic obtained using the above-described method for preparing multiphase ceramics.

[0014] In another aspect, this disclosure provides a multiphase ceramic obtained by the above-described method for preparing multiphase ceramics, or the application of the above-described multiphase ceramics in functional devices.

[0015] The technical solution provided in this disclosure has the following advantages:

[0016] This disclosure provides a multiphase ceramic, its preparation method, and its application. By introducing yttrium and the multiphase ceramic, the electrical properties of the single grain boundaries of the ceramic are jointly improved, thereby enhancing the electrical properties of the entire ceramic system. The prepared yttrium-doped calcium copper titanate and strontium copper titanate multiphase ceramic system achieves a wider range and deeper energy level distribution of interface states, resulting in stronger charge storage capacity at the grain boundaries. It also exhibits excellent breakdown field strength and giant dielectric properties, which can improve the performance of functional devices such as capacitor energy storage elements, memory functional devices, and multilayer ceramic capacitors. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0018] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The breakdown field strength diagrams are for the multiphase ceramics prepared in Examples 1-3 of this disclosure;

[0020] Figure 2 Dielectric constant diagrams of the multiphase ceramics prepared in Examples 1-3 of this disclosure;

[0021] Figure 3 Dielectric loss diagrams of the multiphase ceramics prepared in Examples 1-3 of this disclosure;

[0022] Figure 4(a) is a scanning electron microscope image of the multiphase ceramic prepared in Example 1 of this disclosure;

[0023] Figure 4(b) is a scanning electron microscope image of the multiphase ceramic prepared in Example 2 of this disclosure;

[0024] Figure 4(c) is a scanning electron microscope image of the multiphase ceramic prepared in Example 3 of this disclosure;

[0025] Figure 5 A comparison diagram of the breakdown field strength of the multiphase ceramic prepared in Example 2 of this disclosure with that of other single grain boundaries. Detailed Implementation

[0026] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0027] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.

[0028] According to one embodiment of this disclosure, a method for preparing multiphase ceramics is provided, comprising: mixing rare earth element-doped copper calcium titanate ceramic powder with copper strontium titanate ceramic powder, granulating, forming, debinding, and sintering to obtain multiphase ceramics.

[0029] The yttrium-doped calcium copper titanate and strontium copper titanate multiphase ceramic system prepared by the method of this embodiment has excellent breakdown field strength and giant dielectric properties, which can improve the performance of functional devices such as capacitor energy storage elements, memory functional devices, and multilayer ceramic capacitors.

[0030] In some embodiments of this disclosure, during sintering, the debinded green blank is placed on an alumina pad covered with a layer of copper calcium titanate powder. The heating rate during sintering is 150-200℃ / h, for example, any heating rate selected from 156℃ / h, 168℃ / h, 173℃ / h, 186℃ / h, and 198℃ / h. Cooling is performed with the furnace.

[0031] In some embodiments of this disclosure, the sintering atmosphere is an air atmosphere.

[0032] In some embodiments of this disclosure, after pressing the green body, the glue is removed in a debinding furnace. The temperature curve for debinding is as follows: the room temperature is raised to 400°C at a heating rate of 40-60°C / h, held at 400°C for 5 hours, and then cooled back to room temperature at a rate of 40-60°C / h.

[0033] In some embodiments of this disclosure, a method for preparing multiphase ceramics includes: (1) mixing yttrium-doped copper-calcium titanate ceramic powder and copper-strontium titanate powder at a molar ratio of 1:1 and placing them in a ball mill jar, then ball milling them in a planetary ball mill. After ball milling, the solution is dried into powder in a drying blast oven and then filtered through a 100-mesh sieve to obtain the ball-milled mixed powder. (2) placing the mixed powder in a mortar, adding a binder for granulation, filtering the granulated powder through a 60-mesh sieve, allowing the granulated mixed powder to stand, and then pressing the mixed powder into a green body using a pressing mold at a pressure of 8 MPa. (3) The pressed green body is placed on a gasket and placed in a debinding furnace for debinding. After debinding, the green body is placed in copper calcium titanate powder and placed in a muffle furnace for sintering. The sintering temperature is 1000℃ and the holding time is 5 hours. After sintering, the sample is polished to obtain yttrium-doped copper calcium titanate / copper strontium titanate multiphase ceramic.

[0034] In some embodiments of this disclosure, in step (1), preferably, the planetary ball mill rotates at 400 rpm and the milling time is 8 hours; the temperature of the drying blower is set to 60°C and the drying time is 10 hours; the binder is a polyvinyl alcohol solution with a mass fraction of 2%.

[0035] In some embodiments of this disclosure, in step (2), preferably, the size of the granulated powder is between 60 mesh and 100 mesh, the spherical powder particles have good flowability, and the relative humidity of the powder is 5 to 10% RH; the standing time of the granulated powder is 24 to 48 hours; a cylindrical mold made of stainless steel is used when pressing the green blank, and the mass of each green blank is 0.8 to 1.2 grams.

[0036] In some embodiments of this disclosure, in step (3), preferably, the glue removal temperature during the glue removal process is 400°C, the holding time is 5 hours, and the heating rate and cooling rate are both 40-60°C / hour; during the sintering process, the heating rate of the muffle furnace is 200°C / hour, and the cooling rate is 150°C / hour; the sintered ceramic sample needs to be polished on 800 mesh, 2000 mesh and velvet cloth in sequence, and the polished ceramic surface should be mirror-like and flat.

[0037] In some embodiments of this disclosure, a method for preparing yttrium-doped copper-calcium titanate ceramic powder includes the following steps: (a) mixing yttrium oxide, calcium carbonate, copper oxide, and titanium dioxide of at least analytical purity in a molar ratio of 1.5:2:9:12, weighing the mixture, placing it in a ball mill jar, and then adding anhydrous ethanol to the ball mill jar until it does not exceed 3 / 4 of the jar's volume (preferably, the volume of anhydrous ethanol is 3 / 4 of the jar's volume), and then ball milling the jar in a planetary ball mill for 8 hours. (b) drying the ball-milled mixture in a forced-air drying oven to obtain powder, passing the powder through a 100-mesh sieve, placing it in an alumina crucible, and then calcining the crucible in a muffle furnace. Preferably, in step (b), the sintering temperature for calcining the yttrium-doped copper-calcium titanate ceramic powder is 900°C, the calcination time is 8 hours, the heating rate is 150°C / hour, and the cooling rate is 150°C / hour.

[0038] In some embodiments of this disclosure, a method for preparing strontium copper titanate ceramic powder includes the following steps: (A) mixing strontium carbonate (SrCO3), copper oxide (CuO), and titanium dioxide (TiO2) with a purity not lower than analytical grade in a molar ratio of 1:3:4, adding the mixture to a ball mill jar, and adding anhydrous ethanol as a solvent. The volume of anhydrous ethanol should not exceed 3 / 4 of the volume of the ball mill jar, and the ball milling time is 8 hours. (B) After ball milling, drying the solution and passing it through a 100-mesh sieve, placing the sieved powder into a crucible for calcination II, and passing the calcined powder through a 100-mesh sieve to obtain yttrium-doped calcium copper titanate ceramic powder. Preferably, in step (B), the calcination conditions for calcining the strontium copper titanate ceramic powder are 850°C and the holding time is 8 hours.

[0039] To further illustrate the effects of this disclosure, specific embodiments are described below.

[0040] Example 1

[0041] A method for preparing multiphase ceramics

[0042] Follow these steps:

[0043] (1) Preparation of yttrium-doped copper calcium titanate powder.

[0044] a. Based on the fact that the chemical formula of yttrium-doped calcium copper titanate is Ca... 0.85 Y 0.1 Cu3Ti4O 12 Using a precision balance with an accuracy of at least 0.01 g and weighing paper, analytical grade yttrium oxide, calcium carbonate, copper oxide, and titanium dioxide were weighed in the form of 1.46 g, 11.01 g, 30.90 g, and 41.64 g respectively using a sample spoon. After weighing, all were poured into a ball mill jar.

[0045] b. Add anhydrous ethanol to the ball mill jar until it reaches 2 / 3 of its volume. Then, place the ball mill jar in the ball mill and secure it. Mill for 8 hours at a speed of 400 rpm. Pour the milled mixture into an evaporating dish and place it in a drying oven to dry at 60°C for 12 hours.

[0046] c. The dried mixed powder is passed through a 100-mesh sieve. The sieved mixed powder is then poured into a crucible and placed in a muffle furnace for calcination I at a temperature of 900℃ for 8 hours. The calcined powder is then passed through a 100-mesh sieve again to obtain yttrium-doped copper titanate calcium powder.

[0047] (2) Preparation of Strontium Copper Titanate Powder

[0048] a. Using a precision balance with an accuracy of at least 0.01 g and weighing paper, weigh analytical grade strontium carbonate, copper oxide, and titanium dioxide in the form of 19.13 g, 30.90 g, and 41.64 g respectively using a sample spoon. After weighing, pour all the contents into a ball mill jar.

[0049] b. Add anhydrous ethanol to the ball mill jar until it reaches 2 / 3 of its volume. Then, place the ball mill jar in the ball mill and secure it. Mill for 8 hours at a speed of 400 rpm. Pour the milled mixture into an evaporating dish and place it in a drying oven to dry at 60°C for 12 hours.

[0050] c. The dried mixed powder is passed through a 100-mesh sieve. The sieved mixed powder is poured into a crucible and placed in a muffle furnace for calcination II. The calcination temperature is 850℃ and the calcination time is 8 hours. The calcined powder is then passed through a 100-mesh sieve again to obtain copper strontium titanate powder.

[0051] (3) Preparation of multiphase ceramics

[0052] a. Mix the yttrium-doped copper calcium titanate powder and copper strontium titanate powder obtained in steps (1) and (2) at a molar ratio of 1:1 and put them into a ball mill jar. Add 3 / 4 of the volume of anhydrous ethanol to the ball mill jar and place the ball mill jar into a planetary ball mill. The ball milling time is 8 hours and the rotation speed is 400 rpm.

[0053] b. Pour the ball-milled mixture into an evaporating dish, place it in a drying oven to dry at 60°C for 12 hours, and then pass the dried powder through a 100-mesh sieve.

[0054] c. Take 20 grams of polyvinyl alcohol and add it to 980 grams of deionized water. Stir the mixture at 90°C using a heated magnetic stirrer. After stirring for 2 hours, a polyvinyl alcohol solution with a mass fraction of 2% is formed.

[0055] d. Place the mixed powder from step b into a mortar, and use a dropper to evenly drop the polyvinyl alcohol solution from step c into the mixed powder to granulate it. After granulation, pass the powder through a 60-mesh sieve. The granulated mixed powder exhibits good flowability.

[0056] e. After granulation, the mixed powder is allowed to stand for 24 hours. Then, the mixed powder is pressed into a green compact using a stainless steel mold in a tablet press. The pressure of the tablet press is 20 MPa, and the holding time is 15 seconds.

[0057] f. The pressed green body is placed in a debinding furnace for debinding. The debinding temperature is 400℃, the holding time is 5 hours, and the heating rate and cooling rate are both 60℃ / hour.

[0058] g. Place the debonded green blank on an alumina pad covered with a layer of cooked powder, and put it into a muffle furnace for sintering. The sintering atmosphere is air, the sintering temperature is 1000℃, the holding time is 5 hours, the heating rate is 200℃ / hour, and the cooling rate is 150℃ / hour.

[0059] h. The sintered samples were polished with 800-grit and 2000-grit sandpaper, and then polished with a cloth on a sand mill to obtain the final multiphase ceramic sample.

[0060] i. The performance of the multiphase ceramic sample prepared by h is tested.

[0061] Example 2

[0062] Based on the chemical formula of yttrium-doped calcium copper titanate, which is Ca... 0.25 Y 0.5 Cu3Ti4O 12 Using a precision balance with an accuracy of at least 0.01 grams and weighing paper, analytical grade yttrium oxide, calcium carbonate, copper oxide, and titanium dioxide were weighed in the form of 7.19 grams, 3.18 grams, 30.33 grams, and 40.70 grams, respectively, using a sample spoon. The remaining steps were the same as in Example 1.

[0063] Example 3

[0064] Based on the chemical formula of yttrium-doped calcium copper titanate, which is Ca... 0.1 Y 0.6 Cu3Ti4O 12 Using a precision balance with an accuracy of at least 0.01 grams and weighing paper, 8.58 grams of analytical grade yttrium oxide, 1.27 grams of calcium carbonate, 30.19 grams of copper oxide, and 40.51 grams of titanium dioxide were weighed using a sample spoon. The remaining steps were the same as in Example 1.

[0065] Performance test results analysis:

[0066] Figure 1The voltage-current diagrams are for multiphase ceramic samples of calcium copper titanate ceramic powders with different yttrium element ratios prepared under sintering conditions of 1000°C and 5 hours in Examples 1-3 of this disclosure. Figure 1 As shown, the breakdown field strengths of Examples 1 to 3 are 32.36 kV / cm, 35.82 kV / cm, and 22.42 kV / cm, respectively, which are significantly improved compared to the 1 to 2 kV / cm of pure calcium copper titanate ceramics.

[0067] Figure 2 The dielectric constant diagrams are for multiphase ceramic samples of calcium copper titanate ceramic powders with different yttrium element ratios prepared under sintering conditions of 1000°C and 5 hours in Examples 1-3 of this disclosure. Figure 2 As shown, Examples 1-3 maintained a giant dielectric constant of around 1000, thus preserving the characteristics of a giant dielectric constant.

[0068] Figure 3 The dielectric loss diagrams are for multiphase ceramic samples of calcium copper titanate ceramic powders with different yttrium element ratios prepared under sintering conditions of 1000°C and 5 hours in Examples 1-3 of this disclosure. Figure 3 As shown, the dielectric loss of Examples 1 and 2, especially the dielectric loss in the low frequency band (<100Hz), is significantly reduced. Example 1 has a minimum dielectric loss of 0.036 at 7Hz, and Example 2 has a minimum dielectric loss of 0.038 at 10Hz.

[0069] Figures 4(a), 4(b), and 4(c) are scanning electron microscope images of the multiphase ceramics prepared in Examples 1, 2, and 3 of this disclosure, respectively. As can be seen from Figures 4(a), 4(b), and 4(c), the average grain sizes of Examples 1, 2, and 3 are 6.39 μm, 6.82 μm, and 7.08 μm, respectively, which are significantly improved compared to the 3.48 μm of the undoped yttrium sample. Since the breakdown field strength is the product of the number of grain boundaries and the breakdown field strength of a single grain boundary, this indicates that the technical solution of this disclosure increases the overall breakdown field strength by increasing the breakdown field strength of a single grain boundary rather than by increasing the number of grain boundaries in the sample.

[0070] Figure 5 This is a comparison diagram of the breakdown field strength of the multiphase ceramic prepared in Example 2 of this disclosure with that of single grain boundaries prepared by other methods. Figure 5 As shown, the single grain boundary breakdown field strength of the multiphase ceramic obtained by the preparation method of this embodiment is 24V. Since the interface state distribution with a wider range and deeper energy level is obtained in this embodiment, the charge storage capacity at the grain boundary is stronger. Therefore, it can withstand more electron injection during the breakdown process, effectively improving the voltage withstand capability of the single grain boundary. Therefore, the single grain boundary breakdown field strength in this embodiment is much higher than that of materials obtained by other preparation methods. Figure 5Sample No. 6 is a multiphase ceramic of calcium copper titanate and strontium copper titanate, with a single grain boundary breakdown field of 10.88 V. Compared with other samples, it can be seen that the heterogeneous structure system based on multiphase ceramics can significantly improve the single grain boundary breakdown field. Yttrium ions, as trivalent ions, capture electrons while occupying calcium, creating acceptor-type defect structures near the grain boundaries in the calcium copper titanate ceramic lattice, which can accommodate more electron injection. Strontium copper titanate is used to form the interface of the calcium copper titanate and strontium copper titanate multiphase ceramic. The presence of the double perovskite heterogeneous interface leads to more dangling empty bonds, resulting in an increase in the interface state density. Therefore, carriers need higher energy to cross the potential barrier on the heterogeneous grain boundary. Together, these two elements constitute a wider range and deeper energy level interface state distribution.

[0071] Therefore, the method for preparing multiphase ceramics provided in this disclosure, when the molar ratio of yttrium-doped calcium copper titanate to strontium copper titanate is 1:1, produces a multiphase ceramic system with a breakdown field strength as high as 35.82 kV / cm (compared to 1-2 kV / cm for traditional calcium copper titanate), a dielectric constant above 1000, a dielectric loss as low as 0.036 (compared to 0.1 for traditional calcium copper titanate), and a single grain boundary breakdown field strength greater than 24 V, which is much higher than 3 V in traditional calcium copper titanate ceramics, thus significantly improving the energy storage density of calcium copper titanate ceramics.

[0072] In summary, this disclosure provides a multiphase ceramic, its preparation method, and its applications. By introducing yttrium and the multiphase, the electrical properties of the ceramic single-crystal boundaries are jointly improved, thereby enhancing the electrical properties of the entire ceramic system. The prepared yttrium-doped calcium copper titanate and strontium copper titanate multiphase ceramic system exhibits excellent breakdown field strength and giant dielectric properties, which can improve the performance of functional devices such as capacitor energy storage elements, memory devices, and multilayer ceramic capacitors. Furthermore, the multiphase ceramic provided in this disclosure is prepared using a solid-state method, resulting in a simple, highly operable, environmentally friendly, and low-cost equipment preparation method.

[0073] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0074] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing multiphase ceramics, characterized in that, include: Rare earth element-doped calcium copper titanate ceramic powder and strontium copper titanate ceramic powder are mixed, granulated, prepared, debinded, and sintered to obtain the multiphase ceramic. The molar ratio of the rare earth element-doped copper copper calcium ceramic powder to the copper copper strontium ceramic powder is 1:

1. The rare earth element doping content in the calcium copper titanate ceramic powder is 1.44~8.45%; The rare earth element-doped copper calcium titanate ceramic powder is yttrium element-doped copper calcium titanate ceramic powder. The method for preparing the yttrium-doped copper calcium titanate ceramic powder includes: mixing a yttrium-containing compound, a titanium-containing compound, a copper-containing compound, and a calcium-containing compound, and calcining them to prepare the yttrium-doped copper calcium titanate ceramic powder. And / or, the method for preparing the copper strontium titanate ceramic powder includes: mixing a titanium-containing compound, a copper-containing compound, and a strontium-containing compound, and calcining them to prepare copper strontium titanate ceramic powder.

2. The preparation method according to claim 1, characterized in that, The heating procedure for degreasing is as follows: heat up to 350-450℃ at a rate of 40-60℃ / h, hold for 4-6h, and then cool down to room temperature at a rate of 40-60℃ / h. And / or, the sintering heating program is as follows: heat to 990~1010℃ at a rate of 150~200℃ / h, hold for 4~8h, and cool naturally to room temperature.

3. The preparation method according to claim 1, characterized in that, The calcination I is carried out at a temperature of 900~950℃ for 8~10 hours. And / or, the calcination II is carried out at a temperature of 850~900℃ for a time of 6~8h.

4. The preparation method according to claim 3, characterized in that, The molar ratio of the yttrium-containing compound, calcium-containing compound, copper-containing compound, and titanium-containing compound is (0.1~0.6):(0.30~2.55):9:12; And / or, the molar ratio of the strontium-containing compound, the copper-containing compound, and the titanium-containing compound is 1:3:

4.

5. The preparation method according to claim 4, characterized in that, The yttrium-containing compound is yttrium oxide, the titanium-containing compound is titanium dioxide, the copper-containing compound is copper oxide, the calcium-containing compound is calcium carbonate, and the strontium-containing compound is strontium carbonate.

6. A multiphase ceramic obtained by the preparation method of multiphase ceramic according to any one of claims 1 to 5.

7. An application of the multiphase ceramic of claim 6 in a functional device.

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