A high-dielectric barium titanate material and its solid-state sintering preparation method and application

Abstract

This invention relates to a high-dielectric barium titanate material, its solid-state sintering preparation method, and its application. The solid-state sintering preparation method includes the following steps: barium titanate powder is sequentially ground, decarburized, and subjected to a first crushing process to obtain fine barium titanate powder; the fine barium titanate powder is sequentially sintered and subjected to a second crushing process to obtain the high-dielectric barium titanate material; the particle size of the barium titanate powder obtained from the first crushing process is the same as that of the powder obtained from the grinding process. This invention, through grinding, decarburization, and the first crushing process, ensures that the barium titanate powder has a small and uniform particle size, enabling the formation of a uniform and dense microstructure during subsequent sintering. This improves upon the problems of low barium titanate purity, unacceptable particle size, and low dielectric constant caused by traditional solid-state sintering methods.

Description

Technical Field

[0001] This invention belongs to the field of inorganic non-metallic materials technology, and relates to a dielectric material, particularly a high-dielectric barium titanate material and its preparation method and application by solid-state sintering. Background Technology

[0002] Barium titanate is a functional ceramic material with a typical ABO3-type perovskite lattice structure, exhibiting hexagonal, cubic, tetragonal, orthorhombic, and trigonal phases. Among these, the orthorhombic and tetragonal barium titanate phases exhibit spontaneous polarization, thus possessing significantly high dielectric constants, excellent piezoelectric / ferroelectric properties, and a positive temperature coefficient effect, making them widely applicable in many electronic components. Furthermore, as an orthorhombic polar material, the dielectric properties of barium titanate vary considerably with temperature.

[0003] Existing technologies typically employ liquid-phase synthesis or solid-phase sintering to prepare barium titanate. CN118652114A discloses a tetragonal barium titanate powder and its hydrothermal synthesis process, which can prepare high-purity barium titanate powder with high dielectric constant. However, the raw materials used are expensive, the processing technology is complex, and the required pressure and temperature are high, resulting in high investment and construction costs. At the same time, a large amount of wastewater needs to be discharged during the hydrothermal synthesis process, causing serious environmental pollution.

[0004] Traditional solid-state sintering involves placing the mixed raw materials into a muffle furnace for sintering until barium titanate crystals are formed, followed by pulverization. Barium titanate ceramics sintered using this traditional method have large particle sizes, low material activity, and are prone to introducing impurities, resulting in a low dielectric constant in the final product.

[0005] Furthermore, barium titanate exhibits a significant abrupt change in dielectric constant near the Curie point, indicating poor node temperature stability. Therefore, improving the solid-state sintering process to achieve large-scale industrial production of barium titanate with high dielectric constant and high temperature stability is a pressing technical challenge. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a high-dielectric barium titanate material, its solid-state sintering preparation method, and its application. The solid-state sintering preparation method can form a uniform and dense microstructure, thereby improving the problems of low purity of barium titanate, inability to meet powder particle size requirements, and low dielectric constant caused by traditional solid-state sintering methods.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a solid-state sintering preparation method for a high-dielectric barium titanate material, the preparation method comprising the following steps:

[0009] Barium titanate powder is successively ground, decarbonized, and subjected to a first crushing process to obtain fine barium titanate powder; the fine barium titanate powder is then successively sintered and subjected to a second crushing process to obtain the high-dielectric barium titanate material.

[0010] The particle size of the barium titanate fine powder obtained from the first crushing process is the same as the particle size of the powder obtained from the grinding process.

[0011] The high-dielectric barium titanate material of the present invention has a dielectric constant of more than 3000 F / m at -55℃, a dielectric constant of more than 3000 F / m at 25℃, and a peak value of more than 10000 F / m at the Curie point.

[0012] The solid-state sintering preparation method provided by this invention has advantages over liquid-phase synthesis methods, including high efficiency, abundant raw material sources, low initial investment, simple process, high degree of automation, low labor intensity, and easier industrialization. Furthermore, it generates no wastewater, waste gas, or waste residue during the entire preparation process. Moreover, through grinding, carbon removal, and a first crushing process, this invention ensures that the barium titanate powder has a small and uniform particle size, enabling the formation of a uniform and dense microstructure during subsequent sintering. This improves upon the problems of low barium titanate purity, unacceptable particle size, and low dielectric constant caused by traditional solid-state sintering methods.

[0013] Preferably, the median particle size D50 of the barium titanate powder is 0.8 μm-3.5 μm.

[0014] Preferably, the median particle size D50 of the barium titanate fine powder is 0.6 μm-1.5 μm.

[0015] Preferably, the grinding method includes sand milling; the median particle size D50 of the powder obtained by sand milling is 0.6μm-1.5μm.

[0016] Preferably, the carbon removal treatment includes: removing carbon at 450℃-800℃ for 8h-18h.

[0017] Preferably, the carbon removal process further includes drying before carbon removal, wherein the drying temperature is 80℃-180℃ and the time is 6h-18h.

[0018] Preferably, the first crushing process includes depolymerization.

[0019] Preferably, the sintering heating rate is 2℃ / min-20℃ / min, more preferably 2℃ / min-10℃ / min.

[0020] Preferably, the maximum sintering temperature is 1200℃-1500℃.

[0021] Preferably, the holding time for sintering at the highest temperature is 0.5h-3h.

[0022] Preferably, the second crushing process includes depolymerization, and the resulting high-dielectric barium titanate material has a median particle size D50 of 0.6 μm-1.5 μm.

[0023] Preferably, the barium titanate powder is prepared by the following method: mixing a barium source and a titanium source to obtain a raw material powder; then pre-firing the raw material powder to obtain a pre-firing blank; and then crushing the obtained pre-firing blank.

[0024] Preferably, the barium source includes barium carbonate and / or barium oxide.

[0025] Preferably, the titanium source includes titanium dioxide.

[0026] Preferably, the molar ratio of Ba in the barium source to Ti in the titanium source is 0.990:1-1.010:1.

[0027] Preferably, the particle size of the raw material powder is 0.8μm-3.5μm.

[0028] Preferably, the preheating rate is 1℃ / min-20℃ / min, and more preferably 5℃ / min-10℃ / min.

[0029] Preferably, the maximum pre-firing temperature is 1150℃-1350℃.

[0030] Preferably, the preheating time at the highest temperature is 30 min to 180 min.

[0031] Preferably, the method for crushing and processing the raw materials includes depolymerization.

[0032] In a second aspect, the present invention provides a high-dielectric barium titanate material, which is prepared by the solid-state sintering preparation method described in the first aspect.

[0033] Thirdly, the present invention provides an application of a high-dielectric barium titanate material, which is used in piezoelectric devices or ferroelectric devices.

[0034] The high-dielectric barium titanate material is the high-dielectric barium titanate material prepared by the solid-state sintering preparation method described in the first aspect, or the high-dielectric barium titanate material described in the second aspect.

[0035] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] This invention, through grinding, carbon removal, and a first crushing process, produces barium titanate powder with small and uniform particle size. This allows for the formation of a uniform and dense microstructure during subsequent sintering. This improves upon the problems of low barium titanate purity, unacceptable particle size, and low dielectric constant caused by traditional solid-state sintering methods. The resulting high-dielectric barium titanate material exhibits a dielectric constant exceeding 3000 F / m at -55℃, exceeding 3000 F / m at 25℃, and a peak value exceeding 10000 F / m at the Curie point, while also exhibiting low dielectric loss. Attached Figure Description

[0038] Figure 1 The graph shows the relationship between the dielectric constant and temperature of the high-dielectric barium titanate material obtained in Example 1. Detailed Implementation

[0039] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0040] An embodiment of the present invention provides a solid-state sintering preparation method for a high-dielectric barium titanate material, the solid-state sintering preparation method comprising the following steps:

[0041] Barium titanate powder is successively ground, decarbonized, and subjected to a first crushing process to obtain fine barium titanate powder; the fine barium titanate powder is then successively sintered and subjected to a second crushing process to obtain the high-dielectric barium titanate material.

[0042] The particle size of the barium titanate fine powder obtained from the first crushing process is the same as the particle size of the powder obtained from the grinding process.

[0043] The solid-state sintering preparation method provided by this invention has advantages over liquid-phase synthesis methods, including high efficiency, abundant raw material sources, low initial investment, simple process, high degree of automation, low labor intensity, and easier industrialization. Furthermore, it generates no wastewater, waste gas, or waste residue during the entire preparation process. Moreover, through grinding, carbon removal, and a first crushing process, this invention ensures that the barium titanate powder has a small and uniform particle size, enabling the formation of a uniform and dense microstructure during subsequent sintering. This improves upon the problems of low barium titanate purity, unacceptable particle size, and low dielectric constant caused by traditional solid-state sintering methods.

[0044] In some embodiments, the median particle size D50 of the barium titanate powder is 0.8 μm-3.5 μm, for example, it can be 0.8 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm or 3.5 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] In some embodiments, the median particle size D50 of the barium titanate fine powder is 0.6 μm-1.5 μm, for example, it can be 0.6 μm, 0.8 μm, 1 μm, 1.2 μm or 1.5 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0046] In some embodiments, the grinding method includes sand milling; the median particle size D50 of the powder obtained by sand milling is 0.6μm-1.5μm, for example, it can be 0.6μm, 0.8μm, 1μm, 1.2μm or 1.5μm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0047] This invention does not specifically limit the grinding method, time, or other parameters. As long as the median particle size D50 of the powder obtained by grinding is 0.6μm-1.5μm, it is acceptable. Generally speaking, controlling the grinding time to 30min-180min can achieve the technical effect of the median particle size D50 of the material obtained by grinding being 0.6μm-1.5μm.

[0048] Grinding can further refine the particle size of barium titanate powder, increasing its specific surface area as the particle size decreases, which is beneficial for subsequent sintering to obtain a dense, high-dielectric barium titanate material. However, during the process of particle size refinement, the fine particles re-aggregate under the influence of van der Waals forces and electrostatic double-layer interactions. Therefore, as a preferred technical solution, a dispersant is used during grinding to prevent the barium titanate powder from agglomerating. Consequently, a carbon removal process is required after grinding to remove the dispersant.

[0049] This invention does not impose specific limitations on the amount or type of dispersant, as long as the dispersion effect during grinding can be achieved.

[0050] In some embodiments, the carbon removal process includes: removing carbon at 450°C-800°C for 8-18 hours.

[0051] The carbon removal temperature is 450℃-800℃, for example, it can be 450℃, 500℃, 600℃, 700℃ or 800℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0052] The carbon removal time is 8h-18h, for example, it can be 8h, 10h, 12h, 15h, 16h or 18h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0053] In some embodiments, water is used as the grinding medium in the sand milling process. Water has a good dispersing effect. During the sand milling process, it is adsorbed on the surface of solid particles, which reduces the interfacial tension between liquid and solid and liquid, making the surface of the aggregated solid particles easier to wet and preventing the agglomeration of fine particles. However, the residual water is not conducive to the subsequent sintering.

[0054] In some embodiments, the carbon removal process further includes drying prior to carbon removal, wherein the drying temperature is 80°C-180°C and the drying time is 6h-18h.

[0055] The drying temperature is 80℃-180℃, for example, it can be 80℃, 100℃, 120℃, 150℃, 160℃ or 180℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0056] The drying time is 6h-18h, for example, it can be 6h, 8h, 10h, 12h, 15h, 16h or 18h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0057] In some embodiments, the method of the first fragmentation process includes depolymerization.

[0058] The carbon removal process after grinding causes the barium titanate powder to agglomerate. In order to meet the requirements for fine powder particle size during sintering and obtain a uniform and dense high-dielectric barium titanate material, it is necessary to deagglomerate the agglomerated barium titanate powder through a first crushing process, thereby obtaining fine barium titanate powder with uniform particle size distribution, which is conducive to obtaining a high-dielectric barium titanate material with a high dielectric constant.

[0059] For example, depolymerization is carried out in an air jet mill.

[0060] In some embodiments, to obtain barium titanate fine powder with a median particle size D50 of 0.6 μm-1.5 μm by air jet milling and to reduce the operating pressure of the air jet mill, the first crushing process includes coarse crushing by jaw crusher, fine crushing by roller mill, and deagglomeration by air jet milling in sequence. The terms "coarse crushing" and "fine crushing" are relative concepts, meaning that the average particle size of the material obtained from coarse crushing is greater than the average particle size of the material obtained from fine crushing.

[0061] In some embodiments, the sintering heating rate is 2℃ / min-20℃ / min, for example, it can be 2℃ / min, 5℃ / min, 10℃ / min, 15℃ / min or 20℃ / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 2℃ / min-10℃ / min.

[0062] In this invention, the starting temperature for sintering is room temperature, for example, it can be 15℃-30℃, for example, it can be 15℃, 18℃, 20℃, 25℃, 28℃ or 30℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0063] In some embodiments, the maximum sintering temperature is 1200℃-1500℃, for example, it can be 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, 1450℃ or 1500℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0064] In some embodiments, the holding time of the sintering at the highest temperature is 0.5h-3h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h or 3h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0065] In some embodiments, the second crushing process includes depolymerization, and the median particle size D50 of the resulting high-dielectric barium titanate material is 0.6 μm-1.5 μm, for example, it can be 0.6 μm, 0.8 μm, 1 μm, 1.2 μm or 1.5 μm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0066] For example, depolymerization is carried out in an air jet mill.

[0067] In some embodiments, to obtain high-dielectric barium titanate material with a median particle size D50 of 0.6 μm-1.5 μm by air jet milling and to reduce the operating pressure of the air jet mill, the second crushing process includes sequential coarse crushing by jaw crusher, fine crushing by roller mill, and deagglomeration by air jet milling. The terms "coarse crushing" and "fine crushing" are relative concepts, meaning that the average particle size of the material obtained from coarse crushing is greater than the average particle size of the material obtained from fine crushing.

[0068] In some embodiments, the barium titanate powder is prepared by the following method: mixing a barium source and a titanium source to obtain a raw material powder; then pre-firing the raw material powder to obtain a pre-firing blank; and then crushing the obtained pre-firing blank.

[0069] Pre-calcination allows the titanium and barium sources to undergo a solid-state reaction, eliminating moisture, volatile impurities, gases, and some organic matter from the raw materials, thereby improving the purity of the prepared barium titanate powder. Furthermore, the barium titanate powder obtained through pre-calcination exhibits lower sintering shrinkage and significantly reduced porosity during subsequent sintering, which promotes dense sintering and uniform grain size refinement of barium titanate, and also contributes to improving the dielectric constant of barium titanate.

[0070] In some embodiments, the barium source includes barium carbonate and / or barium oxide.

[0071] In some embodiments, the titanium source includes titanium dioxide.

[0072] In some embodiments, the molar ratio of Ba in the barium source to Ti in the titanium source is 0.990:1 to 1.010:1, for example, it can be 0.990:1, 0.995:1, 1.000:1, 1.005:1 or 1.010:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0073] In some embodiments, the median particle size D50 of the raw material powder is 0.8μm-3.5μm, for example, it can be 0.8μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm or 3.5μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0074] To obtain raw material powder with a median particle size D50 of 0.8μm-3.5μm, the barium source and titanium source were first mixed in a three-dimensional mixer, and then an air jet mill was used to obtain raw material powder with a median particle size D50 of 0.8μm-3.5μm.

[0075] In some embodiments, the median particle size D50 of the barium source is 3μm-15μm, for example, it can be 3μm, 5μm, 8μm, 10μm, 12μm or 15μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0076] In some embodiments, the median particle size D50 of the titanium source is 3μm-15μm, for example, it can be 3μm, 5μm, 8μm, 10μm, 12μm or 15μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0077] In some embodiments, the preheating rate is 1°C / min to 20°C / min, for example, 1°C / min, 3°C / min, 5°C / min, 8°C / min, 10°C / min, 12°C / min, 15°C / min, 18°C / min or 20°C / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 5°C / min to 10°C / min.

[0078] In this invention, the starting temperature for pre-firing is room temperature, for example, it can be 15℃-30℃, for example, it can be 15℃, 18℃, 20℃, 25℃, 28℃ or 30℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0079] In some embodiments, the maximum preheating temperature is 1150°C-1350°C, for example, it can be 1150°C, 1200°C, 1250°C, 1300°C or 1350°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0080] In some embodiments, the preheating time at the highest temperature is 30 min to 180 min, for example, it can be 30 min, 50 min, 80 min, 100 min, 120 min, 150 min, 160 min or 180 min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0081] In some embodiments, the raw material crushing process includes depolymerization.

[0082] For example, depolymerization is carried out in an air jet mill.

[0083] In some embodiments, to obtain barium titanate powder with a median particle size of 0.8 μm-3.5 μm by air jet milling and to reduce the operating pressure of the air jet mill, the raw material crushing process includes sequential coarse crushing by jaw crusher, fine crushing by roller mill, and deagglomeration by air jet milling. The terms "coarse crushing" and "fine crushing" are relative concepts; that is, the average particle size of the material obtained from coarse crushing is greater than the average particle size of the material obtained from fine crushing.

[0084] One embodiment of the present invention provides a high-dielectric barium titanate material, which is prepared by the solid-state sintering preparation method described in any embodiment.

[0085] One embodiment of the present invention provides an application of a high-dielectric barium titanate material, which is used in piezoelectric or ferroelectric devices.

[0086] The high-dielectric barium titanate material is the high-dielectric barium titanate material prepared by the solid-state sintering preparation method described in any embodiment, or the high-dielectric barium titanate material described in any embodiment.

[0087] To clearly illustrate the technical solution of the present invention, the room temperature in the following specific embodiments is 25°C.

[0088] Example 1

[0089] This embodiment provides a solid-state sintering preparation method for high-dielectric barium titanate materials, the solid-state sintering preparation method comprising:

[0090] (1) Weigh barium carbonate with a median particle size D50 of 10 μm and titanium dioxide with a median particle size D50 of 10 μm according to a molar ratio of 1:1, perform preliminary mixing in a three-dimensional mixer, and then pulverize and mix the mixed raw materials by an air jet mill to obtain raw material powder with a median particle size D50 of 2 μm.

[0091] (2) The raw material powder is loaded into a sagger and vibrated on a vibrating table to make the material fully compacted. Then, evenly honeycomb-shaped exhaust ports are punched out and the material is placed in a muffle furnace for pre-firing. The initial temperature during pre-firing is room temperature, the maximum temperature is 1200℃, the heating rate is 8℃ / min, and the material is held at the maximum temperature for 120min to obtain the pre-fired billet.

[0092] (3) The pre-fired billet is successively subjected to coarse crushing by a jaw crusher, fine crushing by a double roller mill, and deagglomeration by an air jet mill to obtain barium titanate powder with a median particle size D50 of 2μm.

[0093] (4) Barium titanate powder is subjected to sand milling treatment, and the median particle size D50 of the powder obtained by sand milling treatment is 1μm;

[0094] (5) The powder after sand milling is dried at 150°C for 10 hours and then carbon is removed at 600°C for 12 hours. Then the powder after carbon removal is subjected to coarse crushing by a crusher, fine crushing by a roller mill and deagglomeration by an air jet mill to obtain barium titanate fine powder with a median particle size D50 of 1 μm.

[0095] (6) The barium titanate fine powder is loaded into a sagger and placed on a vibrating table to vibrate and compact the material. Then, the vents are punched out in a uniform honeycomb pattern and placed in a muffle furnace for sintering. The initial sintering temperature is room temperature, the maximum temperature is 1400℃, the heating rate is 8℃ / h, and the holding time is 2h. After sintering, the sintered material is obtained.

[0096] (7) The sintered material is successively subjected to coarse crushing by a jaw crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain a high dielectric barium titanate material with a median particle size D50 of 1 μm.

[0097] The relationship between the dielectric constant and temperature of the high-dielectric barium titanate material obtained in this embodiment is shown in the figure below. Figure 1 As shown.

[0098] Example 2

[0099] This embodiment provides a solid-state sintering preparation method for high-dielectric barium titanate materials, the solid-state sintering preparation method comprising:

[0100] (1) Weigh barium carbonate with a median particle size D50 of 3 μm and titanium dioxide with a median particle size D50 of 3 μm according to a molar ratio of 1:1, perform preliminary mixing in a three-dimensional mixer, and then pulverize and mix the mixed raw materials by an air jet mill to obtain raw material powder with a median particle size D50 of 0.8 μm.

[0101] (2) The raw material powder is loaded into a sagger and vibrated on a vibrating table to make the material fully compacted. Then, evenly honeycomb-shaped exhaust ports are punched out and the material is placed in a muffle furnace for pre-firing. The initial temperature during pre-firing is room temperature, the maximum temperature is 1150℃, the heating rate is 5℃ / min, and the temperature is held at the maximum temperature for 180min to obtain the pre-fired billet.

[0102] (3) The pre-fired billet is successively subjected to coarse crushing by a jaw crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain barium titanate powder with a median particle size D50 of 0.8 μm.

[0103] (4) Barium titanate powder is subjected to sand milling treatment, and the median particle size D50 of the powder obtained by sand milling treatment is 0.6μm;

[0104] (5) The powder after sand milling is dried at 80°C for 18 hours, and then carbon is removed at 450°C for 18 hours. Then the powder after carbon removal is subjected to coarse crushing by a crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain barium titanate fine powder with a median particle size D50 of 0.6 μm.

[0105] (6) The barium titanate fine powder is loaded into a sagger and placed on a vibrating table to vibrate and compact the material. Then, the vents are punched out in a uniform honeycomb pattern and placed in a muffle furnace for sintering. The initial sintering temperature is room temperature, the maximum temperature is 1200℃, the heating rate is 2℃ / h, and the holding time is 3h. After sintering, the sintered material is obtained.

[0106] (7) The sintered material is successively subjected to coarse crushing by a jaw crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain a high dielectric barium titanate material with a median particle size D50 of 0.6 μm.

[0107] Example 3

[0108] This embodiment provides a solid-state sintering preparation method for high-dielectric barium titanate materials, the solid-state sintering preparation method comprising:

[0109] (1) Weigh barium carbonate with a median particle size D50 of 15 μm and titanium dioxide with a median particle size D50 of 15 μm according to a molar ratio of 1:1, perform preliminary mixing in a three-dimensional mixer, and then pulverize and mix the mixed raw materials by an air jet mill to obtain raw material powder with a median particle size D50 of 3.5 μm.

[0110] (2) The raw material powder is loaded into a sagger and vibrated on a vibrating table to make the material fully compacted. Then, evenly honeycomb-shaped exhaust ports are punched out and the material is placed in a muffle furnace for pre-firing. The initial temperature during pre-firing is room temperature, the maximum temperature is 1350℃, the heating rate is 10℃ / min, and the material is held at the maximum temperature for 30 minutes to obtain the pre-fired billet.

[0111] (3) The pre-fired billet is successively subjected to coarse crushing by a jaw crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain barium titanate powder with a median particle size D50 of 3.5 μm.

[0112] (4) The barium titanate powder was subjected to sand milling treatment, and the median particle size D50 of the powder obtained by sand milling treatment was 1.5 μm;

[0113] (5) The powder after sand milling is dried at 180℃ for 6 hours, and then carbon is removed at 800℃ for 8 hours; then the powder after carbon removal is subjected to coarse crushing by a crusher, fine crushing by a roller mill and deagglomeration by an air jet mill to obtain barium titanate fine powder with a median particle size D50 of 1.5μm.

[0114] (6) The barium titanate fine powder is loaded into a sagger and placed on a vibrating table to vibrate and compact the material. Then, evenly distributed vents are punched out and the material is placed in a muffle furnace for sintering. The initial sintering temperature is room temperature, the maximum temperature is 1500℃, the heating rate is 10℃ / h, and the holding time is 0.5h. The sintered material is obtained after sintering.

[0115] (7) The sintered material is successively subjected to coarse crushing by a jaw crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain a high dielectric barium titanate material with a median particle size D50 of 1.5 μm.

[0116] Example 4

[0117] This embodiment provides a solid-state sintering preparation method for high-dielectric barium titanate material. Except for the molar ratio of barium carbonate to titanium dioxide being 0.990:1, the rest is the same as in Example 1.

[0118] Example 5

[0119] This embodiment provides a solid-state sintering preparation method for high-dielectric barium titanate material. Except for the molar ratio of barium carbonate to titanium dioxide being 1.010:1, the rest is the same as in Example 1.

[0120] Example 6

[0121] This embodiment provides a solid-state sintering preparation method for high-dielectric barium titanate materials. Except for the carbon removal temperature of 400°C, the rest is the same as in Example 1.

[0122] Example 7

[0123] This embodiment provides a solid-state sintering preparation method for high-dielectric barium titanate materials. Except for the carbon removal temperature of 850°C, the rest is the same as in Example 1.

[0124] Example 8

[0125] This embodiment provides a solid-state sintering preparation method for high-dielectric barium titanate materials, which is the same as that in Example 1 except that drying is not performed.

[0126] Comparative Example 1

[0127] This comparative example provides a solid-state sintering preparation method for barium titanate material, the solid-state sintering preparation method comprising:

[0128] (1) Weigh barium carbonate with a median particle size D50 of 10 μm and titanium dioxide with a median particle size D50 of 10 μm according to a molar ratio of 1:1, perform preliminary mixing in a three-dimensional mixer, and then pulverize and mix the mixed raw materials by an air jet mill to obtain raw material powder with a median particle size D50 of 2 μm.

[0129] (2) The raw material powder is loaded into a sagger and vibrated on a vibrating table to make the material fully compacted. Then, evenly honeycomb-shaped exhaust ports are punched out and the material is placed in a muffle furnace for pre-firing. The initial temperature during pre-firing is room temperature, the maximum temperature is 1200℃, the heating rate is 8℃ / min, and the material is held at the maximum temperature for 120min to obtain the pre-fired billet.

[0130] (3) The pre-fired billet is successively subjected to coarse crushing by a jaw crusher, fine crushing by a double roller mill, and deagglomeration by an air jet mill to obtain barium titanate powder with a median particle size D50 of 2μm.

[0131] (4) Barium titanate powder was dried at 150°C for 10 hours and then dehydrated at 600°C for 12 hours. The dehydrated powder was then subjected to coarse crushing by a crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain barium titanate fine powder with a median particle size D50 of 2 μm.

[0132] (5) The barium titanate fine powder is loaded into a sagger and placed on a vibrating table to vibrate and compact the material. Then, the vents are punched out in a uniform honeycomb pattern and placed in a muffle furnace for sintering. The initial sintering temperature is room temperature, the maximum temperature is 1400℃, the heating rate is 8℃ / h, and the holding time is 2h. After sintering, the sintered material is obtained.

[0133] (6) The sintered material is successively subjected to coarse crushing by a jaw crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain a high dielectric barium titanate material with a median particle size D50 of 1 μm.

[0134] Comparative Example 2

[0135] This comparative example provides a solid-state sintering preparation method for barium titanate material, the solid-state sintering preparation method comprising:

[0136] (1) Weigh barium carbonate with a median particle size D50 of 10 μm and titanium dioxide with a median particle size D50 of 10 μm according to a molar ratio of 1:1, perform preliminary mixing in a three-dimensional mixer, and then pulverize and mix the mixed raw materials by an air jet mill to obtain raw material powder with a median particle size D50 of 2 μm.

[0137] (2) The raw material powder is loaded into a sagger and vibrated on a vibrating table to make the material fully compacted. Then, evenly honeycomb-shaped exhaust ports are punched out and the material is placed in a muffle furnace for pre-firing. The initial temperature during pre-firing is room temperature, the maximum temperature is 1200℃, the heating rate is 8℃ / min, and the material is held at the maximum temperature for 120min to obtain the pre-fired billet.

[0138] (3) The pre-fired billet is successively subjected to coarse crushing by a jaw crusher, fine crushing by a double roller mill, and deagglomeration by an air jet mill to obtain barium titanate powder with a median particle size D50 of 2μm.

[0139] (4) Barium titanate powder is subjected to sand milling treatment, and the median particle size D50 of the powder obtained by sand milling treatment is 1μm;

[0140] (5) The powder obtained from the sand milling process is placed into a sagger and placed on a vibrating table to vibrate and compact the material. Then, evenly distributed honeycomb-shaped vents are punched out and the material is placed in a muffle furnace for sintering. The initial sintering temperature is room temperature, the maximum temperature is 1400℃, the heating rate is 8℃ / h, and the holding time is 2h. After sintering, the sintered material is obtained.

[0141] (6) The sintered material is successively subjected to coarse crushing by a jaw crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain a high dielectric barium titanate material with a median particle size D50 of 1 μm.

[0142] Performance Characterization

[0143] The high-dielectric barium titanate material obtained in the above embodiments and the barium titanate material obtained in the comparative example were pressed into circular samples with a diameter of 30 mm and a thickness of 4 mm under a pressure of 20 MPa. The dielectric properties of the circular samples were tested in a temperature range of -55℃ to 200℃, and the results are shown in Table 1.

[0144] Table 1

[0145]

[0146]

[0147] In summary, this invention, through grinding, carbon removal, and a first crushing process, produces barium titanate powder with a fine and uniform particle size. This allows for the formation of a uniform and dense microstructure during subsequent sintering. This improves upon the problems of low barium titanate purity, unacceptable particle size, and low dielectric constant caused by traditional solid-state sintering methods. The resulting high-dielectric barium titanate material exhibits a dielectric constant exceeding 3000 F / m at -55℃, exceeding 3000 F / m at 25℃, and a peak value exceeding 10000 F / m at the Curie point, while also exhibiting low dielectric loss.

[0148] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A solid-state sintering preparation method for a high-dielectric barium titanate material, characterized in that, The solid-state sintering preparation method includes the following steps: Barium titanate powder is successively ground, decarbonized, and subjected to a first crushing process to obtain fine barium titanate powder; the fine barium titanate powder is then successively sintered and subjected to a second crushing process to obtain the high-dielectric barium titanate material. The particle size of the barium titanate fine powder obtained from the first crushing process is the same as the particle size of the powder obtained from the grinding process.

2. The solid-state sintering preparation method according to claim 1, characterized in that, The median particle size D50 of the barium titanate powder is 0.8 μm-3.5 μm; And / or, the median particle size D50 of the barium titanate fine powder is 0.6 μm-1.5 μm.

3. The solid-state sintering preparation method according to claim 1, characterized in that, The grinding method includes sand milling; the median particle size D50 of the powder obtained by sand milling is 0.6μm-1.5μm; And / or, the carbon removal treatment includes: performing carbon removal at 450℃-800℃ for 8h-18h; And / or, the method of the first crushing process includes depolymerization.

4. The solid-state sintering preparation method according to claim 1, characterized in that, The heating rate for sintering is 2℃ / min-20℃ / min; And / or, the maximum sintering temperature is 1200℃-1500℃; And / or, the holding time of the sintering under the highest temperature condition is 0.5h-3h.

5. The solid-state sintering preparation method according to claim 1, characterized in that, The second crushing process includes depolymerization, and the resulting high-dielectric barium titanate material has a median particle size D50 of 0.6 μm-1.5 μm.

6. The solid-state sintering preparation method according to any one of claims 1-5, characterized in that, The barium titanate powder is prepared by the following method: mixing barium source and titanium source to obtain raw material powder; then pre-calcining the raw material powder to obtain pre-calcined billet; and then crushing the obtained pre-calcined billet.

7. The solid-state sintering preparation method according to claim 6, characterized in that, The barium source includes barium carbonate and / or barium oxide; And / or, the titanium source includes titanium dioxide; And / or, the molar ratio of Ba in the barium source to Ti in the titanium source is 0.990:1-1.010:1; And / or, the median particle size D50 of the raw material powder is 0.8μm-3.5μm.

8. The solid-state sintering preparation method according to claim 6 or 7, characterized in that, The preheating rate is 1℃ / min-20℃ / min; And / or, the maximum pre-firing temperature is 1150℃-1350℃; And / or, the preheating time at the highest temperature is 30 min to 180 min; And / or, the method for crushing and processing the raw materials includes depolymerization.

9. A high-dielectric barium titanate material, characterized in that, The high-dielectric barium titanate material is prepared by the solid-state sintering preparation method according to any one of claims 1-8.

10. An application of a high-dielectric barium titanate material, characterized in that, The high-dielectric barium titanate material is used in piezoelectric or ferroelectric devices. The high-dielectric barium titanate material is the high-dielectric barium titanate material prepared by the solid-state sintering preparation method according to any one of claims 1-8, or the high-dielectric barium titanate material according to claim 9.

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