MeTiO3 high-entropy dielectric ceramic material and preparation method thereof

Abstract

The invention relates to a MeTiO3 high-entropy dielectric ceramic material and a preparation method thereof, the chemical formula of the MeTiO3 high-entropy dielectric ceramic material is (Ca < 0-0.4 > Sr < 0-0.4 > Ba < 0-0.4 > Mg < 0-0.4 > Bi < 0-0.15 > Na < 0-0.15 >) TiO3, elements break through the solid solution limit, and higher solid solubility is obtained in a material system, so that a single-phase solid solution is obtained. The microstructure of the material is influenced by introducing entropy engineering, the optimized microstructure of the ceramic can reduce scattering of an electric field at a grain boundary, the dielectric loss is reduced, and the dielectric constant is improved. The high-entropy effect can promote the formation of a single-phase solid solution, so that a polar nanometer micro-region is formed in the material, and the dielectric loss of the material is reduced; the lattice distortion effect can enhance the polarization effect of the material, so that the dielectric constant of the material is improved; the hysteresis diffusion effect can reduce the grain size and enhance the grain boundary effect, so that the breakdown field strength of the material is improved. In addition, the entropy engineering design can also regulate and control the type and number of defects in the ceramic material, so that migration and distribution of electrons and ions are influenced, the sintering temperature is greatly reduced, the heat preservation time is shortened, and the production cost is remarkably reduced.

Description

Technical Field

[0001] This invention relates to the field of functional ceramic materials technology, specifically to an A-site high-entropy MeTiO3 dielectric ceramic material and its preparation method. Background Technology

[0002] Dielectric ceramic materials are a class of functional materials with high dielectric constant, low dielectric loss, and excellent electrical insulation properties, widely used in electronic components such as capacitors, microwave devices, sensors, and energy storage devices. Traditional dielectric ceramic materials, such as barium titanate (BaTiO3) and strontium titanate (SrTiO3), have been widely studied and used due to their excellent dielectric properties. However, as modern electronic devices develop towards miniaturization, high performance, and multifunctionality, traditional dielectric ceramic materials have gradually revealed some limitations, such as the contradiction between dielectric constant and temperature stability, high dielectric loss, and insufficient mechanical properties.

[0003] In recent years, high-entropy materials (HEMs) have attracted widespread attention in the field of materials science as an emerging material system. High-entropy ceramics (HECs), also known as high-entropy compounds, initially referred to single-phase solid solution ceramics composed of at least four elements distributed in equal or near-equal proportions on a cation sublattice. Later, this concept was extended to systems composed of at least four main elements, with each main element having an atomic percentage between 5% and 35%. Increasing the mixing entropy can significantly enhance the solid solution content of the solid solution, thereby generating high-entropy effects, hysteresis diffusion effects, lattice distortion effects, and cocktail effects in high-entropy systems. Research on high-entropy ceramics is still in its early stages but has already become a research hotspot in the field of new materials. By controlling the elemental composition in high-entropy ceramics, their microstructure (such as reducing grain size and lattice distortion) and physical properties (such as reducing dielectric loss and improving temperature stability) can be affected, thereby effectively improving the electrical, thermal, and mechanical properties of the material.

[0004] In the field of dielectric ceramic materials, high-entropy design, by introducing multiple elements to form complex solid solution structures, can effectively control the lattice distortion, defect concentration, and microstructure of the material, thereby optimizing its dielectric properties. Furthermore, the multi-element synergistic effect of high-entropy dielectric ceramic materials can effectively suppress grain growth, improve the material's density and uniformity, and further enhance its overall performance.

[0005] The invention disclosed in publication number CN 112960978 A is titled "A High-Entropy Perovskite Oxide MeTiO3 Thermoelectric Ceramics at the A-Site and Its Preparation Method Thereof". The high-entropy perovskite oxide at the A-site disclosed in this invention is (Ca... 0.2 Sr 0.2 Ba 0.2 La0.2 Pb 0.2 TiO3 and (Ca 0.25 Sr 0.25 Ba 0.25 Me 0.25 The invention uses a solid-state reaction method to prepare high-entropy perovskite oxides, characterized only by phase composition and microstructure, but without studying the dielectric properties of the material.

[0006] The invention disclosed in publication number CN112897989 B is titled "A B-site high-entropy perovskite oxide Sr". 0.9 La 0.1 The invention, titled "MO3 Ceramics and Their Preparation Methods," discloses a B-site high-entropy perovskite oxide as Sr... 0.9 La 0.1 MO3 (M = Zr, Ti, Sn, Hf, Mn, Nb). This invention uses a solid-state reaction method to prepare high-entropy perovskite oxides, characterizing only the phase composition and microstructure, but not studying the dielectric properties of the material.

[0007] Ruihu Mi et al. published "Dielectric and ferroelectric characteristics of Ba(Ti)" in DOI:10.1016 / j.jmat.2023.01.005. 0.25 Zr 0.25 Hf 0.25 Sn 0.25 The paper, titled "O3 High-Entropyceramics," describes the preparation of equimolar amounts of B-site high-entropy perovskite oxides, Ba(TiO3)2, using a solid-state reaction method. 0.25 Zr 0.25 Hf 0.25 Sn 0.25 O3 has a dielectric constant of only 70, which is too low to meet the requirements of miniaturization, high performance and multifunctionality of modern electronic devices.

[0008] In DOI:10.1016 / j.ceramint.2019.11.239, Shiyu Zhou et al. published "Microstructure and dielectric properties of high entropy Ba(Zr)2". 0.2 Ti 0.2 Sn 0.2 Hf 0.2 Me 0.2The paper, titled "Ba(Zr)O3 perovskite oxides," describes the preparation of a series of Ba(Zr) perovskite oxides using a solid-state reaction method. 0.2 Ti 0.2 Sn 0.2 Hf 0.2 Me 0.2 O3(Me=Y) 3+ 、Nb 5+ Ta 5+ V 5+ Mo 6+ W 6+ The study investigated perovskite oxides and their dielectric properties, providing strong evidence that controlling configurational entropy may be a viable approach to establishing highly tunable perovskite structures and exploring novel dielectric materials.

[0009] In DOI:10.1111 / ijac.14962, Qiang He et al. published "Synthesis, characterization, and electrical properties of Nd 3+ -doped(Bi 0.4 Na 0.2 K 0.2 Ba 0.2 The paper, titled "TiO3 high-entropy ceramics," describes the preparation of a series of high-entropy perovskite ceramics using a solid-state reaction method, specifically ceramics with different Nd... 3+ Doping amount (Bi) 0.4 K 0.2 Na 0.2 Ba 0.2 TiO3 has a dielectric constant of 1200, but its breakdown field strength is only 10kV / mm, which cannot meet the requirements of miniaturization and high voltage resistance of modern electronic devices.

[0010] Currently, some studies have explored the preparation and properties of high-entropy dielectric ceramic materials, but there are still problems such as the inability of materials to simultaneously possess high dielectric constant and high breakdown field strength. Therefore, developing a high-entropy dielectric ceramic material with reasonable composition design and excellent performance has important scientific significance and application value. Summary of the Invention

[0011] To overcome the practical application problem that existing dielectric ceramic samples cannot simultaneously possess both high dielectric constant and high breakdown field strength, this invention proposes a MeTiO3 high-entropy dielectric ceramic material and its preparation method.

[0012] The chemical formula of the MeTiO3 high-entropy dielectric ceramic material proposed in this invention is (Ca 0～0.4 Sr0～0.4 Ba 0～0.4 Mg 0～ 0.4 Bi 0～0.15 Na 0～0.15 TiO3.

[0013] The initial raw materials for generating MeTiO3 are CaCO3, SrCO3, BaCO3, Bi2O3, Na2CO3, MgO and TiO2, all of which are analytical grade and have a particle size in the micrometer range.

[0014] The specific process for preparing the MeTiO3 high-entropy dielectric ceramic material proposed in this invention is as follows:

[0015] Step 1, Ingredients:

[0016] Accurately weigh the initial raw materials CaCO3, SrCO3, BaCO3, MgO, Bi2O3, Na2CO3, and TiO2 according to the stoichiometric ratio of the chemical formula of the high-entropy MeTiO3 dielectric ceramic material at site A.

[0017] The amounts of CaCO3, SrCO3, BaCO3, MgO, Bi2O3, Na2CO3, and TiO2 are calculated based on the molar ratio of MeTiO3.

[0018] Step 2, prepare the mixed powder:

[0019] The initial raw materials weighed in step 1 were added to anhydrous ethanol, mixed, and then ball-milled to obtain a mixture. The resulting mixture was then dried to obtain a mixed powder.

[0020] The initial raw material and anhydrous ethanol have a mass ratio of 1:2; the drying temperature is 55–90℃, and the drying time is 12 hours.

[0021] Step 3, Preparation of pre-synthesized powder:

[0022] The obtained mixed powder was placed in a pre-firing furnace at 825–1000°C and held for 2–4 hours to pre-fire the mixed powder. After the holding period, the pre-firing furnace was cooled to 500°C and then cooled to room temperature to obtain the pre-synthesized powder.

[0023] When preparing the pre-synthesized powder, the heating rate of the pre-calcining furnace is 4-10℃ / min, and the cooling rate of the pre-calcining furnace is 4-10℃ / min.

[0024] Step 4, Secondary ball milling:

[0025] Anhydrous ethanol was added to the obtained pre-synthesized powder and the mixture was ball-milled a second time to obtain a mixture.

[0026] The mixture is placed in an oven and dried to obtain a pre-synthesized powder after secondary ball milling.

[0027] The mass ratio of anhydrous ethanol to powder is 2:1; the ball milling time is 8–15 h; the drying temperature is 55–90 °C; and the drying time is 12 h.

[0028] Step 5, Granulation and tableting:

[0029] A PVA aqueous solution was added to the pre-synthesized powder obtained after secondary ball milling; the ratio of the PVA aqueous solution to the mass of the pre-synthesized powder was 1:5. The mixture was thoroughly mixed, sieved, and the microparticles were collected. The microparticles were then placed in a tablet press and pressed into tablets to obtain ceramic green bodies.

[0030] The concentration of the PVA aqueous solution is 5 wt.%; the particles are 50-100 mesh; and the pressure of the tablet press is 100-170 MPa.

[0031] Step 6, Prepare ceramic green body:

[0032] The ceramic green body is placed in an alumina crucible; the crucible is placed in a box furnace, and the furnace is heated to 600–670°C at a rising rate, and held at that temperature for 2–5.5 hours to remove the binder from the ceramic green body. After the holding time is completed, the ceramic green body is cooled to room temperature with the furnace to obtain the unbound ceramic green body.

[0033] The heating rate of the box furnace is 2 to 5.5 °C / min.

[0034] Step 7, Sintering:

[0035] The obtained ceramic green body was placed in an alumina crucible and then placed in a box furnace. The box furnace was heated to 1200–1280°C at a heating rate of 2–5.5°C / min and held for 2–5.5 hours to sinter the ceramic green body. After holding, the temperature was lowered to 500°C at a rate of 4–10°C / min, and then cooled to room temperature in the furnace.

[0036] The sintered ceramic body was removed, polished, and the high-entropy MeTiO3 dielectric ceramic material at the A site was obtained.

[0037] The purpose of this invention is to provide a high-entropy MeTiO3 dielectric ceramic material at the A-site and its preparation method. This method is simple to operate and requires minimal equipment. The obtained high-entropy MeTiO3 dielectric ceramic material possesses both a high dielectric constant and a high breakdown field strength. This invention provides a new approach for the development of high-performance dielectric ceramic materials and has significant practical value for realizing lead-free, miniaturized, and integrated electronic components.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] The chemical formula of the A-site high-entropy MeTiO3 dielectric ceramic material obtained by this invention is (Ca 0～0.4 Sr 0～0.4 Ba 0～0.4 Mg 0～0.4 Bi 0～0.15 Na 0～0.15 TiO3. Because perovskite structures possess at least two cation sublattices, it is possible to design and prepare complex compositions with high entropy at A-site, B-site, and AB-site. Therefore, the independent solubility of the cation and anion sublattices in the perovskite structure results in a disordered configuration, offering a broad space for high-entropy composition design and performance control. The high-entropy material composition design of this invention enables elements to exceed solid solution limits, achieving greater solid solubility in the material system, thereby obtaining a single-phase solid solution. To illustrate how a single-phase solid solution was obtained through "entropy engineering" design, Figure 1 The crystal phase of the high-entropy MeTiO3 dielectric ceramic material at the A site obtained by the process of this invention is shown.

[0040] Entropy engineering in materials design can significantly influence the microstructural characteristics of materials, such as grain size, grain boundary density, and defect distribution, which are closely related to the dielectric properties of dielectric ceramics. By optimizing the microstructure of ceramics (e.g., reducing grain boundary defects and controlling grain size), the scattering of electric field at grain boundaries can be reduced, dielectric loss can be lowered, and the dielectric constant can be increased. The high entropy effect can promote the formation of single-phase solid solutions, creating polar nanoregions within the material, thereby reducing dielectric loss; the lattice distortion effect can enhance the polarization effect, thus increasing the dielectric constant; and the hysteresis diffusion effect can reduce grain size and enhance grain boundary effects, thereby increasing the breakdown field strength. Furthermore, entropy engineering design can also control the type and number of defects in ceramic materials, for example, by optimizing the defect structure through doping or compositional adjustments, thereby affecting the migration and distribution of electrons and ions.

[0041] Table 1 summarizes the sintering conditions and dielectric properties of some reported high-entropy perovskite-structured MeTiO3 dielectric ceramic materials. The dielectric constants of these ceramic materials range from 300 to 780, the dielectric losses from 0.002 to 0.7, and the breakdown field strengths from 32.7 to 177 kV / mm. In this invention, under a holding temperature of 1200℃ to 1270℃ for 2 to 4 hours, the dielectric constant ranges from 311 to 3506 at 25℃ and 1 kHz, and the dielectric loss ranges from 5.26 × 10⁻⁶. -4 ~8.04×10 -3 The breakdown field strength ranges from 13.77 to 21 kV / mm, which greatly reduces the sintering temperature and shortens the holding time, significantly reducing production costs.

[0042] Table 1 Sintering conditions and dielectric properties of perovskite structure dielectric ceramic materials

[0043] Material composition Sintering conditions <![CDATA[ε r ]]> tanδ <![CDATA[E b (kV / mm)]]> <![CDATA[(Ba 0.2 Sr 0.2 Na 0.2 Ca 0.2 La 0.2 (Zr) 0.1 Ti 0.9 )O3]]> 1450℃，9h ～300 ～0.7 32.7 <![CDATA[(Bi 0.28 Nd 0.12 That 0.2 K 0.2 Is 0.2 )TiO3]]> 1140℃，3h ～750 <0.03 10 <![CDATA[0.88NaNbO3-0.12(B i0.9 Na 0.1 )(Fe 0.8 You 0.2 )O3]]> 1250℃， / ～600 <0.002 87.3 <![CDATA[Bi 1 / 7 In 1 / 7 Ba 1 / 7 And 1 / 7 K 1 / 7 Mr. 1 / 7 Here 1 / 7 TiO3 1260℃， / ～780 <0.021 65

[0044] The present invention provides Figures 2-6 The figures show the dielectric constant and dielectric loss of the prepared MeTiO3 dielectric ceramic samples as a function of temperature at different frequencies.

[0045] from Figure 2 As can be seen from the data, within the measurement temperature range, the dielectric peak is below -55℃, the dielectric constant decreases with temperature, and the dielectric loss remains at a low level.

[0046] from Figure 3 As can be seen from the data, within the measurement temperature range, the dielectric peak is located near -20℃, exhibiting slight frequency dispersion and showing characteristics of a relaxor ferroelectric material. The dielectric peak value shifts towards higher temperatures as the frequency increases, while the dielectric loss remains at a low level.

[0047] from Figure 4 As can be seen from the data, within the measurement temperature range, the dielectric peak is below -55℃, the dielectric constant decreases with temperature, and the dielectric loss remains at a low level.

[0048] from Figure 5 As can be seen from the data, within the measurement temperature range, the dielectric peak position is below -55℃, exhibiting slight frequency dispersion and showing characteristics of a relaxor ferroelectric material. Its dielectric peak value shifts towards higher temperatures as the frequency increases, while the dielectric loss remains at a low level.

[0049] from Figure 6 As can be seen from the data, within the measurement temperature range, the dielectric peak is located near -10℃, exhibiting slight frequency dispersion and showing characteristics of a relaxor ferroelectric material. Its dielectric peak value shifts towards higher temperatures as the frequency increases, while the dielectric loss remains at a low level. Attached Figure Description

[0050] Figure 1 The X-ray diffraction pattern of the MeTiO3 dielectric ceramic prepared in this invention.

[0051] Figure 2 The dielectric constant and dielectric loss of the prepared MeTiO3 dielectric ceramic sample are shown as curves of temperature at different frequencies.

[0052] Figure 3 The dielectric constant and dielectric loss of the prepared MeTiO3 dielectric ceramic sample are shown as curves of temperature at different frequencies.

[0053] Figure 4The dielectric constant and dielectric loss of the prepared MeTiO3 dielectric ceramic sample are shown as curves of temperature at different frequencies.

[0054] Figure 5 The dielectric constant and dielectric loss of the prepared MeTiO3 dielectric ceramic sample are shown as curves of temperature at different frequencies.

[0055] Figure 6 The dielectric constant and dielectric loss of the prepared MeTiO3 dielectric ceramic sample are shown as curves of temperature at different frequencies.

[0056] Figure 7 The hysteresis loop diagram of the prepared MeTiO3 dielectric ceramic at the maximum voltage.

[0057] Figure 8 This is a flowchart of the present invention.

[0058] In the picture:

[0059] 1 is (Ca0Sr) 0.25 Ba 0.25 Mg 0.25 Bi 0.125 Na 0.125 X-ray diffraction pattern of TiO3;

[0060] 2 is (Ca) 0.25 Sr0Ba 0.25 Mg 0.25 Bi 0.125 Na 0.125 X-ray diffraction pattern of TiO3;

[0061] 3 is (Ca) 0.15 Sr 0.2 Ba0Mg 0.4 Bi 0.125 Na 0.125 X-ray diffraction pattern of TiO3;

[0062] 4 is (Ca) 0.2 Sr 0.3 Ba 0.2 Mg0Bi 0.15 Na 0.15 X-ray diffraction pattern of TiO3;

[0063] 5 is (Ca) 0.25 Sr 0.25 Ba 0.25 Mg 0.25 X-ray diffraction pattern of Bi0Na0)TiO3;

[0064] 6 is Bi 0.5 Na 0.5X-ray diffraction pattern of TiO3 standard card, PDF#89-3109;

[0065] 7 is the X-ray diffraction pattern of the standard card for MgTiO3, PDF#79-0831;

[0066] 8 are the X-ray diffraction patterns of the standard card for BaTiO3, PDF#79-2263;

[0067] 9 is the X-ray diffraction pattern of the standard card for SrTiO3, PDF#86-0179;

[0068] 10 is the standard card for CaTiO3, X-ray diffraction pattern of PDF#75-2100;

[0069] 11 is (Ca) 0.25 Sr 0.25 Ba 0.25 Mg 0.25 The dielectric constant of Bi0Na0)TiO3 varies with temperature at a frequency of 100 Hz;

[0070] 12 is (Ca 0.25 Sr 0.25 Ba 0.25 Mg 0.25 The dielectric constant of Bi0Na0)TiO3 varies with temperature at a frequency of 1 kHz.

[0071] 13 is (Ca 0.25 Sr 0.25 Ba 0.25 Mg 0.25 The dielectric constant of Bi0Na0)TiO3 varies with temperature at a frequency of 10 kHz.

[0072] 14 is (Ca 0.25 Sr 0.25 Ba 0.25 Mg 0.25 The dielectric constant of Bi0Na0)TiO3 varies with temperature at a frequency of 100kHz.

[0073] 15 is (Ca) 0.25 Sr 0.25 Ba 0.25 Mg 0.25 The dielectric constant of Bi0Na0)TiO3 as a function of temperature at 1MHz;

[0074] 16 is (Ca 0.25 Sr 0.25 Ba 0.25 Mg 0.25The dielectric loss of Bi0Na0)TiO3 as a function of temperature at 100 Hz.

[0075] 17 is (Ca 0.25 Sr 0.25 Ba 0.25 Mg 0.25 The dielectric loss of BiONaO)TiO3 as a function of temperature at 1 kHz.

[0076] 18 is (Ca 0.25 Sr 0.25 Ba 0.25 Mg 0.25 The dielectric loss of Bi0Na0)TiO3 as a function of temperature at 10kHz.

[0077] 19 is (Ca 0.25 Sr 0.25 Ba 0.25 Mg 0.25 The dielectric loss of Bi0Na0)TiO3 varies with temperature at a frequency of 100kHz.

[0078] 20 is (Ca) 0.25 Sr 0.25 Ba 0.25 Mg 0.25 The dielectric loss of Bi0Na0)TiO3 as a function of temperature at 1MHz.

[0079] 21 is (Ca) 0.2 Sr 0.3 Ba 0.2 Mg0Bi 0.15 Na 0.15 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 100 Hz;

[0080] 22 is (Ca 0.2 Sr 0.3 Ba 0.2 Mg0Bi 0.15 Na 0.15 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 1 kHz;

[0081] 23 is (Ca) 0.2 Sr 0.3 Ba 0.2 Mg0Bi 0.15 Na 0.15 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 10 kHz;

[0082] 24 is (Ca) 0.2 Sr 0.3 Ba0.2 Mg0Bi 0.15 Na 0.15 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 100 kHz;

[0083] 25 is (Ca) 0.2 Sr 0.3 Ba 0.2 Mg0Bi 0.15 Na 0.15 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 1 MHz;

[0084] 26 is (Ca 0.2 Sr 0.3 Ba 0.2 Mg0Bi 0.15 Na 0.15 The dielectric loss of TiO3 as a function of temperature at 100 Hz.

[0085] 27 is (Ca) 0.2 Sr 0.3 Ba 0.2 Mg0Bi 0.15 Na 0.15 The dielectric loss of TiO3 as a function of temperature at a frequency of 1 kHz.

[0086] 28 is (Ca 0.2 Sr 0.3 Ba 0.2 Mg0Bi 0.15 Na 0.15 The dielectric loss of TiO3 as a function of temperature at a frequency of 10 kHz.

[0087] 29 is (Ca) 0.2 Sr 0.3 Ba 0.2 Mg0Bi 0.15 Na 0.15 The dielectric loss of TiO3 as a function of temperature at 100kHz.

[0088] 30 is (Ca 0.2 Sr 0.3 Ba 0.2 Mg0Bi 0.15 Na 0.15 The dielectric loss of TiO3 as a function of temperature at a frequency of 1MHz;

[0089] 31 is (Ca) 0.15 Sr 0.2 Ba0Mg 0.4 Bi 0.125 Na 0.125The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 100 Hz;

[0090] 32 is (Ca 0.15 Sr 0.2 Ba0Mg 0.4 Bi 0.125 Na 0.125 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 1 kHz;

[0091] 33 is (Ca 0.15 Sr 0.2 Ba0Mg 0.4 Bi 0.125 Na 0.125 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 10 kHz;

[0092] 34 is (Ca 0.15 Sr 0.2 Ba0Mg 0.4 Bi 0.125 Na 0.125 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 100 kHz;

[0093] 35 is (Ca 0.15 Sr 0.2 Ba0Mg 0.4 Bi 0.125 Na 0.125 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 1 MHz;

[0094] 36 is (Ca 0.15 Sr 0.2 Ba0Mg 0.4 Bi 0.125 Na 0.125 The dielectric loss of TiO3 as a function of temperature at 100 Hz.

[0095] 37 is (Ca 0.15 Sr 0.2 Ba0Mg 0.4 Bi 0.125 Na 0.125 The dielectric loss of TiO3 as a function of temperature at a frequency of 1 kHz.

[0096] 38 is (Ca 0.15 Sr 0.2 Ba0Mg 0.4 Bi 0.125 Na 0.125 The dielectric loss of TiO3 as a function of temperature at a frequency of 10 kHz.

[0097] 39 is (Ca 0.15 Sr 0.2 Ba0Mg 0.4 Bi 0.125 Na 0.125 The dielectric loss of TiO3 as a function of temperature at 100kHz.

[0098] 40 is (Ca) 0.15 Sr 0.2 Ba0Mg 0.4 Bi 0.125 Na 0.125 The dielectric loss of TiO3 as a function of temperature at a frequency of 1MHz;

[0099] 41 is (Ca) 0.3 Sr0Ba 0.3 Mg 0.2 Bi 0.1 Na 0.1 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 100 Hz;

[0100] 42 is (Ca 0.3 Sr0Ba 0.3 Mg 0.2 Bi 0.1 Na 0.1 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 1 kHz;

[0101] 43 is (Ca) 0.3 Sr0Ba 0.3 Mg 0.2 Bi 0.1 Na 0.1 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 10 kHz;

[0102] 44 is (Ca) 0.3 Sr0Ba 0.3 Mg 0.2 Bi 0.1 Na 0.1 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 100 kHz;

[0103] 45 is (Ca) 0.3 Sr0Ba 0.3 Mg 0.2 Bi 0.1 Na 0.1 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 1 MHz;

[0104] 46 is (Ca 0.3 Sr0Ba 0.3 Mg0.2 Bi 0.1 Na 0.1 The dielectric loss of TiO3 as a function of temperature at 100 Hz.

[0105] 47 is (Ca 0.3 Sr0Ba 0.3 Mg 0.2 Bi 0.1 Na 0.1 The dielectric loss of TiO3 as a function of temperature at a frequency of 1 kHz.

[0106] 48 is (Ca 0.3 Sr0Ba 0.3 Mg 0.2 Bi 0.1 Na 0.1 The dielectric loss of TiO3 as a function of temperature at a frequency of 10 kHz.

[0107] 49 is (Ca 0.3 Sr0Ba 0.3 Mg 0.2 Bi 0.1 Na 0.1 The dielectric loss of TiO3 as a function of temperature at 100kHz.

[0108] 50 is (Ca) 0.3 Sr0Ba 0.3 Mg 0.2 Bi 0.1 Na 0.1 The dielectric loss of TiO3 as a function of temperature at a frequency of 1MHz;

[0109] 51 is (Ca0Sr) 0.35 Ba 0.2 Mg 0.3 Bi 0.075 Na 0.075 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 100 Hz;

[0110] 52 is (Ca0Sr) 0.35 Ba 0.2 Mg 0.3 Bi 0.075 Na 0.075 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 1 kHz;

[0111] 53 is (Ca0Sr) 0.35 Ba 0.2 Mg 0.3 Bi 0.075 Na 0.075The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 10 kHz;

[0112] 54 is (Ca0Sr) 0.35 Ba 0.2 Mg 0.3 Bi 0.075 Na 0.075 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 100 kHz;

[0113] 55 is (Ca0Sr) 0.35 Ba 0.2 Mg 0.3 Bi 0.075 Na 0.075 The curve showing the change of the dielectric constant of TiO3 with temperature at a frequency of 1 MHz;

[0114] 56 is (Ca0Sr) 0.35 Ba 0.2 Mg 0.3 Bi 0.075 Na 0.075 The dielectric loss of TiO3 as a function of temperature at 100 Hz.

[0115] 57 is (Ca0Sr) 0.35 Ba 0.2 Mg 0.3 Bi 0.075 Na 0.075 The dielectric loss of TiO3 as a function of temperature at a frequency of 1 kHz.

[0116] 58 is (Ca0Sr) 0.35 Ba 0.2 Mg 0.3 Bi 0.075 Na 0.075 The dielectric loss of TiO3 as a function of temperature at a frequency of 10 kHz.

[0117] 59 is (Ca0Sr) 0.35 Ba 0.2 Mg 0.3 Bi 0.075 Na 0.075 The dielectric loss of TiO3 as a function of temperature at 100kHz.

[0118] 60 is (Ca0Sr) 0.35 Ba 0.2 Mg 0.3 Bi 0.075 Na 0.075 The dielectric loss of TiO3 as a function of temperature at a frequency of 1MHz;

[0119] 61 is (Ca 0.25 Sr 0.25 Ba 0.25 Mg 0.25 Unipolar PE loop of Bi0Na0)TiO3;

[0120] 62 is (Ca 0.2 Sr 0.3 Ba 0.2 Mg0Bi 0.15 Na 0.15 The unipolar PE loop of TiO3;

[0121] 63 is (Ca 0.15 Sr 0.2 Ba0Mg 0.4 Bi 0.125 Na 0.125 The unipolar PE loop of TiO3;

[0122] 64 is (Ca 0.3 Sr0Ba 0.3 Mg 0.2 Bi 0.1 Na 0.1 The unipolar PE loop of TiO3;

[0123] 65 is (Ca0Sr) 0.35 Ba 0.2 Mg 0.3 Bi 0.075 Na 0.075 The unipolar PE loop of TiO3. Detailed Implementation

[0124] This invention relates to a MeTiO3 high-entropy dielectric ceramic material and its preparation method, and its technical solution will be described in detail through five embodiments.

[0125] The chemical formula of the MeTiO3 high-entropy dielectric ceramic material proposed in this invention is (Ca 0～0.4 Sr 0～0.4 Ba 0～0.4 Mg 0～ 0.4 Bi 0～0.15 Na 0～0.15 TiO3.

[0126] The initial raw materials for generating MeTiO3 are CaCO3, SrCO3, BaCO3, Bi2O3, Na2CO3, MgO and TiO2, all of which are analytical grade and have a particle size in the micrometer range.

[0127] In all embodiments of this invention, the reagents used are commercially available analytical grade products, manufactured by Sinopharm Chemical Reagent Co., Ltd., with a purity of >99.9%.

[0128] Table 2 Material composition of each embodiment

[0129]

[0130] The specific process for preparing the A-site high-entropy MeTiO3 dielectric ceramic material proposed in this invention is as follows:

[0131] Step 1, Ingredients:

[0132] The initial raw materials CaCO3, SrCO3, BaCO3, MgO, Bi2O3, Na2CO3, and TiO2 are accurately weighed according to the stoichiometric ratio of the chemical formula of the high-entropy MeTiO3 dielectric ceramic material at site A; the amounts of CaCO3, SrCO3, BaCO3, MgO, Bi2O3, Na2CO3, and TiO2 are calculated based on the molar ratio of MeTiO3.

[0133] Table 3 Initial Raw Material Quantities for Each Embodiment in Step 1 Table 3 Initial Raw Material Quantities

[0134]

[0135] Step 2, prepare the mixed powder:

[0136] The initial raw materials weighed in step 1 are mixed with anhydrous ethanol and then ball-milled for 8–15 hours; the mass ratio of anhydrous ethanol to the initial raw materials is 2:1. The resulting mixture is placed in an oven and dried at 55–90°C for 12 hours to obtain a mixed powder.

[0137] Table 4 Process parameters for each embodiment in step 2

[0138]

[0139] Step 3, Preparation of pre-synthesized powder:

[0140] The mixed powder obtained in step 2 is placed in a pre-calcining furnace. The pre-calcining furnace is heated to 825-1000℃ at a heating rate of 4-10℃ / min and held for 2-4 hours to pre-calcine the mixed powder. After the holding period, the temperature is lowered to 500℃ at a rate of 4-10℃ / min, and then cooled to room temperature with the furnace to obtain the pre-synthesized powder.

[0141] Table 5 Process parameters for each embodiment in step 2

[0142]

[0143]

[0144] Step 4, Secondary ball milling:

[0145] The pre-synthesized powder obtained in step 3 was added to anhydrous ethanol and ball-milled a second time for 8–15 h; the mass ratio of anhydrous ethanol to powder was 2:1, resulting in a mixture. The mixture was then placed in an oven and dried at 55–90 °C for 12 h to obtain the pre-synthesized powder after the second ball milling.

[0146] Table 6 Process parameters for each embodiment in step 4.

[0147]

[0148] Step 5, Granulation and tableting:

[0149] A 5 wt.% PVA aqueous solution was added to the pre-synthesized powder obtained after secondary ball milling; the ratio of the added PVA aqueous solution to the mass of the pre-synthesized powder after secondary ball milling was 1:5. The mixture was thoroughly mixed, sieved, and 50-100 mesh particles were collected. The sieved particles were placed in a tablet press and pressed into tablets at 100-170 MPa to obtain ceramic green bodies.

[0150] Table 7 Process parameters for each embodiment in step 5

[0151]

[0152] Step 6, Prepare ceramic green body:

[0153] An alumina crucible containing the ceramic green body is placed in a box furnace, and the furnace is heated to 600–670°C at a heating rate of 2–5.5°C / min, and held at that temperature for 2–5.5 hours to remove the binder from the ceramic green body. After the holding period, the green body is cooled to room temperature with the furnace to obtain the unbound ceramic green body.

[0154] Table 8. Process parameters for each embodiment in step 6.

[0155]

[0156]

[0157] Step 7, Sintering:

[0158] The obtained ceramic green body was placed in an alumina crucible and then placed in a box furnace. The box furnace was heated to 1200–1280°C at a heating rate of 2–5.5°C / min and held for 2–5.5 hours to sinter the ceramic green body. After holding, the temperature was lowered to 500°C at a rate of 4–10°C / min, and then cooled to room temperature in the furnace.

[0159] The sintered ceramic body was removed, polished, and the high-entropy MeTiO3 dielectric ceramic material at the A site was obtained.

[0160] Table 9 Process parameters for each embodiment in step 7.

[0161]

[0162] To verify the effectiveness of the present invention, its performance was measured:

[0163] I. The phase structure of high-entropy oxides has been determined:

[0164] The instrument used was an X'Pert PRO diffractometer from the Dutch analytical instrument company. High-entropy oxide phase analysis was performed using X-ray diffraction. The scanning angle 2θ = 10–90°, the scanning speed was 5° / min, and the step size was 0.01°. The obtained ceramic diffraction results are as follows: Figure 1 .

[0165] Determination of dielectric temperature spectrum of high-entropy MeTiO3 dielectric ceramic material at site IIA:

[0166] The capacitance C and dielectric loss tanδ of the sample were measured using an E4980A digital bridge from Agilent Technologies and a DMS-2000 high and low temperature dielectric temperature spectrum measurement system from Wuhan Bailibo Co., Ltd., with a heating rate of 3℃ / min.

[0167] The capacitive temperature change rate of the high-entropy MeTiO3 dielectric ceramic material at site A is listed in Table 10.

[0168] Table 10. Temperature variation rate of high-entropy MeTiO3 dielectric ceramic materials at site A.

[0169]

[0170]

[0171] The dielectric properties of the A-site high-entropy MeTiO3 dielectric ceramic material are listed in Table 11. As can be seen, the high-entropy ceramic material of this invention exhibits both a high dielectric constant and high breakdown strength, with a dielectric constant greater than 300 and a breakdown strength greater than 15 kV / mm.

[0172] Table 11 Dielectric properties of high-entropy MeTiO3 dielectric ceramic materials at site A.

[0173] Example <![CDATA[ε r @1kHz]]> tanδ@1kHz BDS(kV / mm) 1 312 <![CDATA[5.26×10 -4 ]]> 16.0 2 3506 <![CDATA[6.37×10 -3 ]]> 13.8 3 726 <![CDATA[7.72×10 -4 ]]> 21.0 4 491 <![CDATA[6.77×10 -3 ]]> 18.6 5 1814 <![CDATA[8.04×10 -3 ]]> 16.9

[0174] Determination of the hysteresis loop of high-entropy MeTiO3 dielectric ceramic material at site IIIA:

[0175] The unipolar hysteresis loop of the sample under maximum electric field conditions was measured using a Multiferroic II 500V ferroelectric analyzer from Radiant Corporation, USA, at room temperature. See details below. Figure 7 .

Claims

1. A MeTiO3 high-entropy dielectric ceramic material, characterized in that, The chemical formula of MeTiO3 high-entropy dielectric ceramic material is (Ca... 0～0.4 Sr 0～0.4 Ba 0～0.4 Mg 0～0.4 Bi 0～0.15 Na 0～0.15 TiO3; The initial raw materials for generating MeTiO3 are CaCO3, SrCO3, BaCO3, Bi2O3, Na2CO3, and MgO. All raw materials, including TiO2, are of analytical grade and have a particle size in the micrometer range.

2. A method for preparing the MeTiO3 high-entropy dielectric ceramic material, characterized in that, The specific process is as follows: Step 1, Ingredients: Accurately weigh the initial raw materials CaCO3, SrCO3, BaCO3, MgO, Bi2O3, Na2CO3, and TiO2 according to the stoichiometric ratio of the chemical formula of the high-entropy MeTiO3 dielectric ceramic material at site A. The amounts of CaCO3, SrCO3, BaCO3, MgO, Bi2O3, Na2CO3, and TiO2 are calculated based on the molar ratio of MeTiO3. Step 2, prepare the mixed powder: The initial raw materials weighed in step 1 are added to anhydrous ethanol, mixed, and then ball-milled to obtain a mixture; the obtained mixture is dried to obtain a mixed powder; Step 3, Preparation of pre-synthesized powder: The obtained mixed powder was placed in a pre-firing furnace at 825-1000℃ and kept at that temperature for 2-4 hours to pre-fire the mixed powder; after the holding time was completed, the pre-firing furnace was cooled to 500℃ and then cooled to room temperature with the furnace to obtain the pre-synthesized powder. Step 4, Secondary ball milling: Anhydrous ethanol was added to the obtained pre-synthesized powder and the mixture was ball-milled a second time to obtain a mixture. The mixture was placed in an oven and dried to obtain a pre-synthesized powder after secondary ball milling; Step 5, Granulation and tableting: PVA aqueous solution was added to the pre-synthesized powder obtained after secondary ball milling; the ratio of the amount of PVA aqueous solution added to the mass of the pre-synthesized powder was 1:5; the mixture was mixed evenly; the powder was sieved; the microparticles were collected; the microparticles were placed in a tablet press and pressed into tablets to obtain ceramic green bodies; Step 6, Prepare ceramic green body: The ceramic green body is placed in an alumina crucible; the crucible is placed in a box furnace, and the box furnace is heated to 600-670°C at a rising rate, and held for 2-5.5 hours to remove the binder from the ceramic green body; after the holding time is completed, the ceramic green body is cooled to room temperature with the furnace to obtain the unbound ceramic green body. Step 7, Sintering: The obtained ceramic green body is placed in an alumina crucible and then placed in a box furnace. The box furnace is heated to 1200-1280℃ at a heating rate of 2-5.5℃ / min and held for 2-5.5h to sinter the ceramic green body. After the holding period, the temperature is reduced to 500℃ at a rate of 4-10℃ / min and cooled to room temperature with the furnace. The sintered ceramic body was removed, polished, and the high-entropy MeTiO3 dielectric ceramic material at the A site was obtained.

3. The method for preparing MeTiO3 high-entropy dielectric ceramic material as described in claim 2, characterized in that, When preparing the mixed powder, the initial raw material to anhydrous ethanol mass ratio is 1:2; the drying temperature is 55-90℃, and the drying time is 12h.

4. The method for preparing MeTiO3 high-entropy dielectric ceramic material as described in claim 2, characterized in that, When preparing the pre-synthesized powder, the heating rate of the pre-calcining furnace is 4-10℃ / min, and the cooling rate of the pre-calcining furnace is 4-10℃ / min.

5. The method for preparing MeTiO3 high-entropy dielectric ceramic material as described in claim 2, characterized in that, The mass ratio of anhydrous ethanol to powder is 2:1; the ball milling time is 8–15 h; the drying temperature is 55–90 °C; and the drying time is 12 h.

6. The method for preparing MeTiO3 high-entropy dielectric ceramic material as described in claim 2, characterized in that, During granulation and tableting, the concentration of the PVA aqueous solution is 5 wt.%; the microparticles are 50-100 mesh; and the pressure of the tableting machine is 100-170 MPa.

7. The method for preparing MeTiO3 high-entropy dielectric ceramic material as described in claim 2, characterized in that, When preparing ceramic green bodies, the heating rate of the box furnace is 2 to 5.5 °C / min.

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