BaTiO3-based ceramic material with high insulation characteristic, giant dielectric constant and low loss

Abstract

The invention discloses a BaTiO3-based ceramic material with high insulation characteristic, giant dielectric constant and low loss, and belongs to the technical field of ceramic preparation. The BaTiO3-based ceramic material is prepared from the following raw materials in parts by mole: 100 parts of BaTiO3, 0.2-0.8 part of Nb2O5, 1.6-3.5 parts of MgCO3, 0.5-1.2 parts of MnO2, 0.8-1.6 parts of CaZrO3, 0.5-1.2 parts of BaSiO3 and 0.8-1.4 parts of rare earth oxide, a core-shell-insulating layer structure is formed by controlling the types, the content and the doping sequence of doped ions and the sintering atmosphere and temperature, a dielectric constant increasing and loss suppression equilibrium system is constructed in the BaTiO3-based ceramic material, and the dielectric constant of the BaTiO3-based ceramic material is increased. According to the BaTiO3-based ceramic material and the preparation method thereof, effective suppression of carrier migration by the insulating layer is achieved, meanwhile, the promotion effect of a defect structure in crystal grains on polarization response is enhanced, and the obtained BaTiO3-based ceramic material has excellent comprehensive electrical properties: in a wide temperature range of-55 to 150 DEG C, the average crystal grain size is smaller than 1 mu m, the dielectric constant is as high as 1 * 10 < 5 >, the dielectric loss is lower than 3.5%, and the dielectric property is excellent. And the insulation resistivity exceeds 8 * 10 < 11 > omega.cm.

Description

Technical Field

[0001] This invention relates to a BaTiO3-based ceramic material with high insulation properties, a large dielectric constant, and low loss, belonging to the field of ceramic preparation technology. Background Technology

[0002] With the miniaturization, lightweighting, and integration of electronic components, the electronics industry demands that multilayer ceramic capacitors (MLCCs) possess high dielectric constants, low dielectric losses, and excellent insulation properties. Currently, several systems of giant dielectric ceramic materials have been extensively studied, such as CaCu3Ti4O... 12 Materials based on (CCTO), BaTiO3, NiO, SrTiO3, and TiO2. However, each system suffers from high dielectric loss, poor insulation performance, and low breakdown field strength to varying degrees, requiring further research to improve the performance of dielectric materials.

[0003] BaTiO3, due to its high dielectric constant and low dielectric loss, is widely used in electronic ceramic materials. However, in the field of giant dielectric materials, the biggest problem with BaTiO3-based dielectrics is that their stability is significantly affected by temperature. Especially near its Curie temperature (125°C), BaTiO3 undergoes a ferroelectric phase transition, leading to a sharp decrease in dielectric constant. Patent CN114230335A, which doped BaTiO3 with MnO2, MgO, MAS, and rare earth oxides, achieved a dielectric constant >10 during sintering under a N2 / H2 atmosphere. 4 The dielectric constant is [value missing], but the dielectric loss range of 0.02–0.05 still exhibits significant fluctuations, and 10 [value missing] 9 The resistivity of Ω·cm is insufficient to meet the stringent insulation performance requirements of high-end MLCCs. Patent CN107686347A uses BaTiO3 powder as a base material, with the addition of 0–2.5 wt% Nb₂O₅ and 1–2 wt% Y₂O₃ by mass percentage, and employs a helium atmosphere and high-temperature sintering at 1300–1320℃, thus increasing the dielectric constant to 5.29 × 10⁻⁶. 4 However, the high-temperature process not only increases energy consumption by more than 30%, but also further increases production costs due to helium's scarcity. Patent CN108610042A describes a process where sintering is carried out at 1320–1400℃ in a reducing atmosphere, resulting in a dielectric constant (40000) and an insulation resistivity (10⁻⁶). 8 ~10 11 The wide range of Ω·cm reflects the insufficient stability of material properties, making it difficult to meet the consistency requirements of industrial production.

[0004] The core challenge in developing giant dielectric barium titanate materials lies in achieving a synergistic optimization of high resistivity, low loss, and large grain structure while simultaneously improving the dielectric constant. Large grain structures typically result in higher dielectric constants but also increase grain boundary defects, exacerbating leakage current and losses. Conversely, small grains, while improving insulation performance, may decrease the dielectric constant. Furthermore, the ferroelectric phase transition characteristics of barium titanate (such as the tetragonal-cubic phase transition near the Curie point) further induce temperature dependence of the dielectric constant, leading to significant performance fluctuations across a wide temperature range. Therefore, how to improve dielectric properties while suppressing losses, enhancing insulation, and structural stability through interface engineering and defect control remains a crucial scientific problem to be solved in this field. Summary of the Invention

[0005] To address or partially address the problems existing in related technologies, this invention provides a BaTiO3-based ceramic material with high insulation properties, a large dielectric constant, and low loss, which improves dielectric properties while suppressing loss, enhancing insulation, and structural stability.

[0006] This invention provides a BaTiO3-based ceramic material with high insulation properties, a large dielectric constant, and low loss, comprising the following molar proportions of raw materials: 100 parts BaTiO3, 0.2-0.8 parts Nb2O5, 1.6-3.5 parts MgCO3, 0.5-1.2 parts MnO2, 0.8-1.6 parts CaZrO3, 0.5-1.2 parts BaSiO3, and 0.8-1.4 parts rare earth oxides; wherein the rare earth oxides include two or more rare earth oxides.

[0007] The preparation method of the BaTiO3-based ceramic material includes:

[0008] (1) BaTiO3, Nb2O5, part of MgCO3, MnO2 and CaZrO3 were mixed and ball-milled, pre-calcined under a reducing atmosphere, and then cooled to obtain pre-calcined powder;

[0009] (2) The pre-fired powder, rare earth oxides, BaSiO3 and the remaining MgCO3 are mixed and ball-milled, dried and sieved to obtain mixed powder. Polyvinyl alcohol solution is added for granulation and pressing to obtain green material. Then the glue is removed, sintered in a reducing atmosphere and kept warm to finally obtain BaTiO3-based ceramic material.

[0010] This invention forms a thinner core-shell structure through pre-firing, which prevents the subsequent diffusion of magnesium, rare earth elements and silicon, and facilitates the formation of a silicon-rich liquid phase on the grain surface.

[0011] Preferably, the BaTiO3-based ceramic material comprises a three-layer structure, wherein the grain core is a lightly doped BaTiO3 phase, the grain shell is a BaTiO3 phase enriched with doped ions, and the outermost layer (grain boundary layer) is an insulating layer formed by a silicon-rich liquid phase coating layer.

[0012] Light doping is defined as a doping concentration of less than 1 mol%. Silicon-rich liquid phases include Si. 4+ Mg 2+ It contains rare earth elements and other ions; it also has a high silicon content, exceeding 20%.

[0013] Preferably, the particle size of the BaTiO3 is 200nm to 400nm.

[0014] Preferably, the rare earth oxide is two or more of the following: yttrium oxide, lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, dysprosium oxide, holmium oxide, erbium oxide, and ytterbium oxide.

[0015] Doping with a single rare-earth oxide can indeed improve the dielectric properties of barium titanate to some extent through lattice distortion and defect engineering. However, single rare-earth oxide doping also has significant problems. For example, the peak value of the thermoelectric rate of change is too sharp, resulting in a narrower applicable temperature range for the material. At the same time, defects introduced by doping can easily lead to increased dielectric loss, and temperature stability is difficult to guarantee, making it difficult to meet the needs of engineering applications. In contrast, using a composite doping method with multiple rare-earth oxides can leverage the synergistic effect between different rare-earth elements, optimizing the material at multiple scales from crystal structure and grain size to grain boundary characteristics, thereby achieving the performance requirements of high dielectric, low loss, and high insulation resistivity.

[0016] Preferably, in step (1), the molar amounts of MgCO3 and Nb2O5 are equal.

[0017] Preferably, in step (1), the pre-firing temperature is 900-1100℃, the pre-firing holding time is 0.5-4h, and the reducing atmosphere is a mixture of N2 and H2, wherein the volume fraction of H2 is 1-4%.

[0018] Preferably, in step (2), the sintering temperature is 1180-1240℃, the holding time is 2-4h, and the reducing atmosphere is a mixture of N2 and H2, wherein the volume fraction of H2 is 1-4%.

[0019] Preferably, the pressing pressure is 2-5 MPa.

[0020] Preferably, in step (2), the mass concentration of the polyvinyl alcohol solution is 3%-6%, and the polyvinyl alcohol solution is added and ground until sand particles are formed and no powder adheres to the mortar.

[0021] Preferably, the temperature for discharging the adhesive is 600-650℃, the holding time for discharging the adhesive is 2-3 hours, and the heating rate is 2℃ / min to 5℃ / min.

[0022] Preferably, in step (2), the sintering atmosphere is a mixture of N2 and H2, the sintering heating rate is 5℃ / min~8℃ / min, the sintering temperature is 1180-1240℃, and the sintering holding time is 2-4h.

[0023] The technical solution provided by this invention may include the following beneficial effects:

[0024] This invention, by controlling the type and content of dopant ions, as well as the sintering atmosphere and temperature, cleverly forms a "core-shell-insulator" structure, successfully constructing a balanced system for improving dielectric constant and suppressing loss in BaTiO3-based ceramic materials. Sintered at 1180℃~1240℃ in a 1~4% N2 / H2 mixed atmosphere, the prepared ceramic material exhibits excellent comprehensive electrical properties: an average grain size of less than 1.0 μm over a wide temperature range of -55~150℃, and a dielectric constant as high as 1×10⁻⁶. 5 The dielectric loss is less than 3.5%, and the insulation resistivity exceeds 8×10⁻⁶. 11 Ω·cm. The method for producing BaTiO3-based ceramic materials described in this invention achieves effective suppression of carrier migration by the insulating layer through precise control of sintering atmosphere and temperature parameters. At the same time, it enhances the promoting effect of internal grain defect structure on polarization response, providing a new approach with engineering application value for developing electronic ceramic materials that combine giant dielectric properties and high insulation properties. Attached Figure Description

[0025] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0026] Figure 1 This is a scanning electron microscope image of the BaTiO3-based ceramic material prepared in Example 3.

[0027] Figure 2 This is a transmission electron microscope (TEM) image of the BaTiO3-based ceramic material prepared in Example 3.

[0028] Figure 3 The image shows the elemental distribution of the BaTiO3-based ceramic material prepared in Example 3. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0030] Example 1

[0031] A BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss is made primarily from 100% BaTiO3 as the main raw material, with the following BaTiO3 dopant modifiers added in the following molar percentages: Nb2O5 0.4%, MgCO3 2.8%, MnO2 1.2%, CaZrO3 0.8%, BaSiO3 0.6%, Yb2O3 0.5%, Dy2O3 0.3%, and Sm2O3 0.3%.

[0032] A method for preparing a BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss includes the following steps:

[0033] (1) Weigh and mix BaTiO3 powder with dopant Nb2O5, a portion of MgCO3 (the same molar amount as Nb2O5), MnO2, and CaZrO3. The planetary ball mill is rotated at 300 r / min. After ball milling for 4 hours, the powder is dried. The powder is pre-calcined in 1% H2 / 99% N2 at 1000℃ for 2 hours. After cooling in the furnace, the pre-calcined powder is obtained.

[0034] (2) The pre-calcined powder obtained in step (1) is mixed with BaSiO3, rare earth oxides and the remaining MgCO3, dried and passed through a 40-mesh sieve to obtain a mixed powder. The mixed powder is placed in an agate mortar and a 5% polyvinyl alcohol (PVA) solution is gradually added and ground to granulate to obtain granulated powder. An appropriate amount of granulated powder is placed in a mold and pressed into a circular green body with a diameter of 10 mm and a thickness of 1 mm under a pressure of 3 MPa. All the prepared green bodies are placed in a debinding furnace for debinding, heated to 600℃ at a heating rate of 5℃ / min, held at that temperature for 2 hours, and then cooled to room temperature with the furnace.

[0035] (3) The sample obtained in step (2) was heated to 1210℃ in a 4% N2 / H2 reducing atmosphere at a heating rate of 5℃ / min and held for 3h. It was then cooled to room temperature in the furnace to obtain a BaTiO3-based ceramic material with high insulation properties, giant dielectric constant and low loss.

[0036] Example 2

[0037] A BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss is made primarily from 100% BaTiO3, with the following molar percentages of dopant modifiers added: 0.5% Nb2O5; 3% MgCO3; 0.9% MnO2; 1% CaZrO3; 0.8% BaSiO3; 0.2% La2O3; 0.6% Yb2O3; and 0.2% Dy2O3.

[0038] A method for preparing a BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss includes the following steps:

[0039] A method for preparing a BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss includes the following steps:

[0040] (1) Weigh and mix BaTiO3 powder with dopant Nb2O5, a portion of MgCO3 (the same molar amount as Nb2O5), MnO2, and CaZrO3. The planetary ball mill is rotated at 300 r / min. After ball milling for 4 hours, the powder is dried. The powder is pre-calcined in 1% H2 / 99% N2 at 1000℃ for 3 hours. After cooling in the furnace, the pre-calcined powder is obtained.

[0041] (2) The pre-calcined powder obtained in step (1) is mixed with BaSiO3, rare earth oxides and the remaining MgCO3, dried and passed through a 40-mesh sieve to obtain a mixed powder sieve. The mixed powder is placed in an agate mortar and a 5% (w / w) polyvinyl alcohol (PVA) solution is gradually added and ground to granulate to obtain granulated powder. An appropriate amount of granulated powder is placed in a mold and pressed into a circular green body with a diameter of 10 mm and a thickness of 1 mm under a pressure of 3 MPa. All the prepared green bodies are placed in a high-temperature furnace for debinding, heated to 600℃ at a heating rate of 5℃ / min, held at that temperature for 2 hours, and then cooled to room temperature with the furnace.

[0042] (3) The sample obtained in step (2) was heated to 1240℃ in a 4% N2 / H2 reducing atmosphere at a heating rate of 5℃ / min and held for 2h. It was then cooled to room temperature in the furnace to obtain the final BaTiO3-based ceramic material with high insulation properties, giant dielectric constant and low loss.

[0043] Example 3:

[0044] A BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss is made primarily from 100% BaTiO3, with the following dopant modifiers added in the following molar percentages: Nb2O5 0.8%; MgCO3 1.6%; MnO2 0.5%; CaZrO3 0.8%; BaSiO3 1.2%; Yb2O3 0.6%; Dy2O3 0.4%; and Ho2O3 0.4%.

[0045] A method for preparing a BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss includes the following steps:

[0046] (1) Weigh and mix BaTiO3 powder with dopant Nb2O5, a portion of MgCO3 (the same molar amount as Nb2O5), MnO2, and CaZrO3. The planetary ball mill is rotated at 300 r / min. After ball milling for 4 h, the powder is dried. The powder is pre-calcined in 4% H2 / 96% N2 at 1100℃ and held for 0.5 h. After cooling in the furnace, a blocky solid is obtained.

[0047] (2) The blocky solid obtained in step (1) is mixed with BaSiO3, rare earth oxides and the remaining MgCO3, dried and passed through a 40-mesh sieve. The mixed powder is placed in an agate mortar, and a 3% polyvinyl alcohol (PVA) solution is gradually added to grind and granulate to obtain granulated powder. An appropriate amount of granulated powder is placed in a mold and pressed into a circular green body with a diameter of 10 mm and a thickness of 1 mm under a pressure of 5 MPa. All the prepared green bodies are placed in a high-temperature furnace for debinding, and the temperature is raised to 620℃ at a heating rate of 2℃ / min, held for 2.5 h, and then cooled to room temperature with the furnace.

[0048] (3) The sample obtained in step (2) was heated to 1200℃ in a 2% N2 / H2 reducing atmosphere at a heating rate of 5℃ / min and held for 2h. It was then cooled to room temperature in the furnace to obtain the final BaTiO3-based ceramic material with high insulation properties, giant dielectric constant and low loss.

[0049] according to Figures 1-3 It can be seen that the BaTiO-based ceramic material prepared in Example 3 exhibits good performance under a 10kx scanning electron microscope (SEM). Figure 1 Under light, a liquid-phase coating with low viscosity and good wettability was observed to form on the surface of the grains. To further analyze its formation mechanism, high-resolution imaging using transmission electron microscopy was employed. Figure 2 As can be seen, there are obvious electric domains inside the grains, exhibiting a "core-shell" structure, and the outer shell is relatively thick, which corroborates the observation results of scanning electron microscopy; further analysis of the shell and surface composition... Figure 3 Surface scanning results show that the main doping element of the liquid phase coating layer on the surface is Si. 4+ Mg 2+ .

[0050] Example 4:

[0051] A BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss is made primarily from 100% BaTiO3, with the following dopant modifiers added in the following molar percentages: Nb2O5 0.2%; MgCO3 3.5%; MnO2 1.2%; CaZrO3 1.6%; BaSiO3 0.5%; Yb2O3 0.4%; Dy2O3 0.2%; and Ho2O3 0.2%.

[0052] A method for preparing a BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss includes the following steps:

[0053] (1) Weigh and mix BaTiO3 powder with dopant Nb2O5, a portion of MgCO3 (the same molar amount as Nb2O5), MnO2, and CaZrO3. The planetary ball mill is rotated at 300 r / min. After ball milling for 4 hours, the powder is dried. The powder is pre-calcined in 3% H2 / 97% N2 at 900℃ for 4 hours. After cooling in the furnace, the pre-calcined powder is obtained.

[0054] (2) The pre-calcined powder obtained in step (1) is mixed with BaSiO3, rare earth oxides and the remaining MgCO3, dried and passed through a 40-mesh sieve. The mixed powder is placed in an agate mortar, and a 6% polyvinyl alcohol (PVA) solution is gradually added to grind and granulate to obtain granulated powder. An appropriate amount of granulated powder is placed in a mold and pressed into a circular green body with a diameter of 10 mm and a thickness of 1 mm under a pressure of 2 MPa. All the prepared green bodies are placed in a high-temperature furnace for debinding, and the temperature is raised to 650℃ at a heating rate of 4℃ / min, held for 3 hours, and then cooled to room temperature with the furnace.

[0055] (3) The sample obtained in step (2) was heated to 1180℃ in a 1% N2 / H2 reducing atmosphere at a heating rate of 8℃ / min and held for 4h. It was then cooled to room temperature in the furnace to obtain the final BaTiO3-based ceramic material with high insulation properties, giant dielectric constant and low loss.

[0056] Comparative Example 1:

[0057] A BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss is made primarily from 100% BaTiO3 as the main raw material, with the following molar percentages of dopant modifiers added: 0.4% Nb2O5, 2.8% MgCO3, 1.2% MnO2, 0.4% CaZrO3, 0.6% BaSiO3, 0.4% Yb2O3, and 0.2% Dy2O3.

[0058] A method for preparing a BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss includes the following steps:

[0059] (1) Weigh and mix BaTiO3 powder with dopant Nb2O5, a portion of MgCO3 (the same molar amount as Nb2O5), MnO2, and CaZrO3. The planetary ball mill is rotated at 300 r / min. After ball milling for 4 hours, the powder is dried. The powder is pre-calcined in 1% H2 / 99% N2 at 1000℃ for 2 hours. After cooling in the furnace, the pre-calcined powder is obtained.

[0060] (2) The pre-calcined powder obtained in step (1) is mixed with BaSiO3, rare earth oxides and the remaining MgCO3, dried and passed through a 40-mesh sieve to obtain a mixed powder. The mixed powder is placed in an agate mortar and a 5% polyvinyl alcohol (PVA) solution is gradually added and ground to granulate to obtain granulated powder. An appropriate amount of granulated powder is placed in a mold and pressed into a circular green body with a diameter of 10 mm and a thickness of 1 mm under a pressure of 3 MPa. All the prepared green bodies are placed in a debinding furnace for debinding, heated to 600℃ at a heating rate of 5℃ / min, held at that temperature for 2 hours, and then cooled to room temperature with the furnace.

[0061] (3) The sample obtained in step (2) was heated to 1210℃ in a 4% N2 / H2 reducing atmosphere at a heating rate of 5℃ / min and held for 3h. It was then cooled to room temperature in the furnace to obtain BaTiO3-based ceramic material.

[0062] Comparative Example 2:

[0063] A BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss is made primarily from 100% BaTiO3, with the following molar percentages of dopant modifiers added: 0.4% Nb2O5, 4% MgCO3, 1.2% MnO2, 0.8% CaZrO3, 0.4% BaSiO3, 0.5% Yb2O3, 0.3% Dy2O3, and 0.3% Sm2O3.

[0064] A method for preparing a BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss includes the following steps:

[0065] (1) Weigh and mix BaTiO3 powder with dopant Nb2O5, a portion of MgCO3 (the same molar amount as Nb2O5), MnO2, and CaZrO3. The planetary ball mill is rotated at 300 r / min. After ball milling for 4 hours, the powder is dried. The powder is pre-calcined in 1% H2 / 99% N2 at 1000℃ for 2 hours. After cooling in the furnace, the pre-calcined powder is obtained.

[0066] (2) The pre-calcined powder obtained in step (1) is mixed with BaSiO3, rare earth oxides and the remaining MgCO3, dried and passed through a 40-mesh sieve to obtain a mixed powder. The mixed powder is placed in an agate mortar and a 5% polyvinyl alcohol (PVA) solution is gradually added and ground to granulate to obtain granulated powder. An appropriate amount of granulated powder is placed in a mold and pressed into a circular green body with a diameter of 10 mm and a thickness of 1 mm under a pressure of 3 MPa. All the prepared green bodies are placed in a debinding furnace for debinding, heated to 600℃ at a heating rate of 5℃ / min, held at that temperature for 2 hours, and then cooled to room temperature with the furnace.

[0067] (3) The sample obtained in step (2) was heated to 1210℃ in a 4% N2 / H2 reducing atmosphere at a heating rate of 5℃ / min and held for 3h. It was then cooled to room temperature in the furnace to obtain BaTiO3-based ceramic material.

[0068] Comparative Example 3

[0069] A BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss is made primarily from 100% BaTiO3 as the main raw material, with the following molar percentages of dopant modifiers added: 0.4% Nb2O5, 2.8% MgCO3, 1.2% MnO2, 0.8% CaZrO3, 0.6% BaSiO3, 0.5% Yb2O3, 0.3% Dy2O3, and 0.3% Sm2O3.

[0070] A method for preparing a BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss includes the following steps:

[0071] (1) Weigh and mix BaTiO3 powder with dopant modifiers Nb2O5, MgCO3, MnO2, CaZrO3, BaSiO3, and rare earth oxides. Mill the mixture in a planetary ball mill at 300 r / min for 4 hours, then dry it. Place the mixed powder in an agate mortar and gradually add a 5% (w / w) polyvinyl alcohol (PVA) solution to grind and granulate the powder. Place an appropriate amount of granulated powder into a mold and press it into round green blanks with a diameter of 10 mm and a thickness of 1 mm under a pressure of 3 MPa. Place all the prepared green blanks into a high-temperature furnace for debinding. Heat the furnace to 600℃ at a rate of 5℃ / min, hold for 2 hours, and then cool to room temperature with the furnace.

[0072] (2) The sample obtained in step (1) was heated to 1210℃ in a 4% N2 / H2 reducing atmosphere at a heating rate of 5℃ / min and held for 3h. The sample was then cooled to room temperature in the furnace to obtain BaTiO3-based ceramic material.

[0073] Comparative Example 4

[0074] A BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss is made primarily from 100% BaTiO3 as the main raw material, with the following molar percentages of dopant modifiers added: 0.4% Nb2O5, 2.8% MgCO3, 1.2% MnO2, 0.8% CaZrO3, 0.6% BaSiO3, 0.5% Yb2O3, 0.3% Dy2O3, and 0.3% Sm2O3.

[0075] A method for preparing a BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss includes the following steps:

[0076] (1) Weigh and mix BaTiO3 powder with doping modifiers Nb2O5, MgCO3, MnO2 and CaZrO3. The planetary ball mill is rotated at 300 r / min. After ball milling for 4 hours, the powder is dried. The powder is pre-calcined in 1% H2 / 99% N2 at 1050℃ for 2 hours. After cooling in the furnace, the pre-calcined powder is obtained.

[0077] (2) The pre-calcined powder obtained in step (1) is mixed with BaSiO3 and rare earth oxides, dried, and then passed through a 40-mesh sieve. The mixed powder is placed in an agate mortar, and 5% polyvinyl alcohol (PVA) is gradually added to grind and granulate to obtain granulated powder. An appropriate amount of granulated powder is placed in a mold and pressed into a circular green body with a diameter of 10 mm and a thickness of 1 mm under a pressure of 3 MPa. All the prepared green bodies are placed in a high-temperature furnace for debinding, and the temperature is raised to 600℃ at a heating rate of 5℃ / min, held for 2 hours, and then cooled to room temperature with the furnace.

[0078] (3) The sample obtained in step (2) was heated to 1200℃ in a 4% N2 / H2 reducing atmosphere at a heating rate of 5℃ / min and held for 2h. It was then cooled to room temperature in the furnace to obtain BaTiO3-based ceramic material.

[0079] Example of effect

[0080] The samples prepared in Examples 1-4 and Comparative Examples 1-4 were polished, and silver electrode paste was uniformly coated on both sides. The samples were then held at 820°C for 15 minutes. The dielectric properties (ε) of the obtained materials under a 1MHz frequency test condition were then measured. 25℃ The dielectric constant at 25℃ is tanδ. 25℃ The dielectric loss at 25℃ is given, the resistance is the room temperature insulation resistance, and ΔC / C is the rate of change of capacitance at temperature, as shown in Table 1.

[0081] Table 1

[0082]

[0083] This invention designs a BaTiO3-based ceramic material with high insulation properties, a large dielectric constant, and low loss. Through a multi-element synergistic doping strategy, Si, Mg, Ca, Zr, Mn, and rare earth elements are introduced during high-temperature solid-state sintering, forming a "core-shell-insulator layer" structure under controlled process. Due to fluctuations in composition and structure, the core is a lightly doped BaTiO3 phase, while the shell is enriched with dopant ions. This allows the material to maintain a stable temperature change rate within ±15% over a wide temperature range of -55℃ to 150℃, exhibiting excellent temperature stability. Furthermore, the high-temperature reducing atmosphere induces the generation of numerous oxygen vacancies and weakly bound electrons in the crystal lattice. This invention introduces a large number of defect dipoles into the lattice through donor and acceptor doping with inequivalent ions (such as rare earth elements and Mn), significantly increasing the defect density. These defect dipoles effectively improve the intrinsic dielectric constant of the material through lattice distortion and optimization of polaron migration paths, thereby achieving a significant improvement in the material's dielectric properties. In addition, the excessive doping of Si at high temperatures... 4+ Mg 2+ Rare earth ions form a glassy phase distributed along the grain boundaries. Upon cooling, a silicon-rich glassy phase coating layer with low dielectric activity, low viscosity, and good wettability is formed on the grain surface. This amorphous coating layer at the grain boundaries forms an effective insulating layer, constructing a physical barrier that restricts the migration of free electrons and greatly suppresses the cross-grain boundary jumping of ionized carriers. This optimization of the microstructure not only significantly reduces the dielectric loss of the material but also achieves a substantial increase in insulation resistivity, thereby improving the overall performance of the material.

[0084] In Comparative Example 3, where no pre-sintering was performed, the raw materials BaTiO3, MgCO3, and MnO2 were directly sintered in a reducing atmosphere without high-temperature pretreatment, resulting in significant deterioration of material properties: the dielectric constant was only 72011, the insulation resistivity was low, and the rate of change of capacitance temperature fluctuated by more than ±15%. The fundamental reason is that MgCO3 directly decomposes into MgO and releases CO gas during sintering. The obstructed gas escape forms internal micropores, reducing the material density and disrupting grain boundary continuity. Simultaneously, the unpre-sintered raw materials failed to achieve chemical homogenization, leading to the presence of doped ions (such as MnO2). 2 Uneven distribution of MgCO3 (+, rare earth ions) leads to lattice distortion in BaTiO3 and failure of the control of the "core-shell-insulator" gradient structure. The pre-sintering process, by decomposing MgCO3 in advance, optimizing the pore structure, promoting the formation of intermediate phases and doping uniformity, not only eliminates porosity and improves density and dielectric constant, but also suppresses grain boundary thermal mismatch through the complete "core-shell" structure, ultimately achieving synergistic optimization of dielectric properties, temperature stability and insulation resistivity.

[0085] In this invention, pre-calcining a mixture of BaTiO3, Nb2O5, a portion of MgCO3, MnO2, and CaZrO3 allows for the formation of a core-shell structure in barium titanate through co-doping. Magnesium, zirconium, and niobium ions all replace Ti sites. Adding all magnesium carbonate at once would result in excessive titanium site replacement, leading to the precipitation of more titanium and the formation of a larger titanium-rich phase. Furthermore, it would create a thicker shell, causing a mismatch between the core and shell layers in the "core-shell" structure, thus affecting the temperature change rate. The second addition of magnesium carbonate, pre-calcined BaSiO3 powder, and rare earth oxides facilitates the formation of a low-viscosity glassy phase on the surface of the lightly doped barium titanate grains after pre-calcination. This maintains a suitable proportion of each component in the "core-shell-insulator" gradient structure. Only when the proportions of these three components are appropriate can the optimal "core-shell-insulator" structure, satisfying the requirements of temperature change rate, high dielectric constant, low loss, and high insulation, be obtained.

[0086] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss, characterized in that: The raw materials comprise the following molar proportions: 100 parts BaTiO3, 0.2-0.8 parts Nb2O5, 1.6-3.5 parts MgCO3, 0.5-1.2 parts MnO2, 0.8-1.6 parts CaZrO3, 0.5-1.2 parts BaSiO3, and 0.8-1.4 parts rare earth oxides; wherein the rare earth oxides include two or more rare earth oxides. The process of developing BaTiO3-based ceramic materials with high insulation properties, large dielectric constant, and low loss involves the following steps: (1) BaTiO3, Nb2O5, part of MgCO3, MnO2 and CaZrO3 were mixed and ball-milled, pre-calcined under a reducing atmosphere, and cooled to obtain pre-calcined powder; (2) The pre-fired powder, rare earth oxides, BaSiO3 and the remaining MgCO3 are mixed and ball-milled, dried and sieved to obtain mixed powder. Polyvinyl alcohol solution is added for granulation and pressing to obtain green material. Then the glue is removed, sintered in a reducing atmosphere and kept warm to finally obtain BaTiO3-based ceramic material.

2. The BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss according to claim 1, characterized in that: The particle size of the BaTiO3 is 200 nm to 400 nm.

3. The BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss according to claim 1, characterized in that: The rare earth oxide is two or more of the following: yttrium oxide, lanthanum oxide, cerium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, dysprosium oxide, holmium oxide, erbium oxide, and ytterbium oxide.

4. The BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss according to claim 1, characterized in that: In step (1), the molar fraction of MgCO3 is the same as that of Nb2O5.

5. The BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss according to claim 1, characterized in that: The pre-firing temperature is 900-1100℃, and the pre-firing holding time is 0.5-4h.

6. The BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss according to claim 1, characterized in that: The pressure for compression molding is 2-5 MPa.

7. The BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss according to claim 1, characterized in that: In step (2), the mass concentration of the polyvinyl alcohol solution is 3%-6%.

8. The BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss according to claim 1, characterized in that: The temperature for discharging the adhesive is 600-650℃, the holding time for discharging the adhesive is 2-3 hours, and the heating rate is 2℃ / min~5℃ / min.

9. The BaTiO3-based ceramic material with high insulation properties, giant dielectric constant, and low loss according to claim 1, characterized in that: In step (2), the reducing atmosphere is a mixture of N2 and H2, the sintering heating rate is 5℃ / min~8℃ / min, the sintering temperature is 1180-1240℃, and the holding time is 2-4h.

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