High-dielectric barium titanate material as well as solid-phase sintering preparation method and application thereof

Abstract

The invention relates to a high-dielectric barium titanate material and a solid-phase sintering preparation method and application thereof, and the solid-phase sintering preparation method comprises the following steps: sequentially carrying out grinding, carbon emission treatment and first crushing treatment on barium titanate powder to obtain barium titanate fine powder; sequentially performing sintering and second crushing treatment on the barium titanate fine powder to obtain the high-dielectric barium titanate material, the particle size of the barium titanate fine powder obtained by the first crushing treatment is the same as that of the powder obtained by grinding. Through grinding, carbon emission treatment and first crushing treatment, the particle size of the barium titanate fine powder is fine and uniform, a uniform and compact microstructure can be formed during subsequent sintering, and the problems that the purity of barium titanate is not high, the particle size of the powder cannot meet the requirement and the dielectric constant is low due to a traditional solid-phase sintering method are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic non-metallic materials, relates to a dielectric material, and particularly relates to a high-dielectric barium titanate material, a solid-phase sintering preparation method thereof, and an application thereof. Background Art

[0002] Barium titanate is a functional ceramic material with a typical ABO3-type perovskite lattice structure, and has crystal phases such as hexagonal phase, cubic phase, tetragonal phase, orthorhombic phase, and rhombohedral phase. Among them, orthorhombic and tetragonal barium titanate have spontaneous polarization phenomena, and thus have remarkable electrical properties such as high dielectric constant, excellent piezoelectric / ferroelectricity, and positive temperature coefficient effect, and can be widely used in many electronic components. In addition, as an orthorhombic polar material, the dielectric properties of barium titanate change greatly with temperature.

[0003] The prior art usually uses a liquid-phase synthesis method or a solid-phase sintering method to prepare barium titanate. CN118652114A discloses a tetragonal barium titanate powder and a hydrothermal synthesis process thereof, which can prepare barium titanate powder with high purity and high dielectric constant, but the raw materials used have high costs, the processing process is complex, and the required pressure and temperature are both high, resulting in high investment and construction scale costs; at the same time, a large amount of waste water needs to be discharged during the hydrothermal synthesis process, causing serious environmental pollution.

[0004] The traditional solid-phase sintering method is to put the mixed raw materials into a muffle furnace for sintering until barium titanate crystals are sintered, and then perform a pulverization treatment. The barium titanate ceramics sintered by the traditional solid-phase sintering method have a large particle size, too low material activity, and are prone to introducing impurities, resulting in a low dielectric constant of the finished product.

[0005] In addition, the dielectric constant of barium titanate has a large mutation near the Curie point, that is, the node temperature stability is poor. Therefore, how to improve the solid-phase sintering process and use the solid-phase sintering process for large-scale industrial production of barium titanate with high dielectric constant and high temperature stability is a technical problem that needs to be solved urgently at present. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a high-dielectric barium titanate material, a solid-phase sintering preparation method thereof, and an application thereof. The solid-phase sintering preparation method can form a uniform and dense microstructure, thereby improving the problems of low purity of barium titanate, inability to meet the requirements of powder particle size, and low dielectric constant caused by the traditional solid-phase sintering method.

[0007] To achieve the purpose of the present invention, the following technical solutions are adopted:

[0008] In the first aspect, the present invention provides a solid-phase sintering preparation method of a high-dielectric barium titanate material, and the preparation method includes the following steps:

[0009] The barium titanate powder is successively subjected to grinding, carbon removal treatment and first crushing treatment to obtain barium titanate fine powder; the barium titanate fine powder is successively subjected to sintering and second crushing treatment to obtain the high-dielectric barium titanate material;

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

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

[0012] The solid-phase sintering preparation method provided by the present invention has the advantages of high efficiency, rich raw material sources, small one-time investment, simple process, high degree of process automation, low labor intensity, easier industrialization, and no generation of waste water, waste gas and waste residue during the whole preparation process compared with the liquid-phase synthesis method. Moreover, through grinding, carbon removal treatment and first crushing treatment, the barium titanate fine powder has a small and uniform particle size, and a uniform and dense microstructure can be formed during subsequent sintering, improving the problems of low purity of barium titanate, inability to meet the required particle size of the powder and low dielectric constant caused by the traditional solid-phase sintering method.

[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 grinding; the median particle size D50 of the powder obtained by the sand grinding is 0.6 μm - 1.5 μm.

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

[0017] Preferably, the carbon removal treatment further includes drying before carbon removal, and the drying temperature is 80 °C - 180 °C and the time is 6 h - 18 h.

[0018] Preferably, the method of the first crushing treatment includes depolymerization.

[0019] Preferably, the heating rate of the sintering is 2 °C / min - 20 °C / min, preferably 2 °C / min - 10 °C / min.

[0020] Preferably, the highest temperature of the sintering is 1200 °C - 1500 °C.

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

[0022] Preferably, the method of the second crushing treatment includes depolymerization, and the median particle size D50 of the obtained high-dielectric barium titanate material is 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 performing a pre-sintering treatment on the raw material powder to obtain a pre-sintered blank; and performing a raw material crushing treatment on the obtained pre-sintered 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 0.8 μm - 3.5 μm.

[0028] Preferably, the heating rate of the pre-sintering is 1 °C / min - 20 °C / min, preferably 5 °C / min - 10 °C / min.

[0029] Preferably, the highest temperature of the pre-sintering is 1150 °C - 1350 °C.

[0030] Preferably, the holding time at the highest temperature during the pre-sintering is 30 min - 180 min.

[0031] Preferably, the method of the raw material crushing treatment includes depolymerization.

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

[0033] In a third aspect, the present invention provides an application of a high-dielectric barium titanate material, and the high-dielectric barium titanate material is used for piezoelectric devices or ferroelectric devices.

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

[0035] The numerical ranges described in the present invention not only include the specific point values exemplified above, but also include any arbitrary point values between the above numerical ranges not exemplified. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the ranges.

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

[0037] Through grinding, carbon removal treatment and first crushing treatment, the present invention makes the particle size of barium titanate fine powder small and uniform, and can form a uniform and dense microstructure during subsequent sintering, improving the problems of low purity of barium titanate, inability to meet the requirements of powder particle size and low dielectric constant caused by the traditional solid-phase sintering method. The dielectric constant of the obtained high-dielectric barium titanate material can reach above 3000 F / m at -55°C, above 3000 F / m at 25°C, and the peak value at the Curie point can reach above 10000 F / m, with low dielectric loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a graph showing the relationship between the dielectric constant and temperature of the high-dielectric barium titanate material obtained in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

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

[0041] The barium titanate powder is successively subjected to grinding, carbon removal treatment and first crushing treatment to obtain barium titanate fine powder; the barium titanate fine powder is successively subjected to sintering and second crushing treatment to obtain the high-dielectric barium titanate material;

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

[0043] Compared with the liquid-phase synthesis method, the solid-phase sintering preparation method provided by the present invention has the advantages of high efficiency, rich raw material sources, small one-time investment, simple process, high degree of process automation, low labor intensity, easier industrialization, and no generation of waste water, waste gas and waste residue during the whole preparation process. Moreover, through grinding, carbon removal treatment and first crushing treatment, the present invention makes the particle size of barium titanate fine powder small and uniform, and can form a uniform and dense microstructure during subsequent sintering, improving the problems of low purity of barium titanate, inability to meet the requirements of powder particle size and low dielectric constant caused by the traditional solid-phase sintering method.

[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. The other unlisted values within the numerical range are equally applicable.

[0045] In some embodiments, the median particle size D50 of the fine barium titanate 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. The other unlisted values within the numerical range are equally applicable.

[0046] In some embodiments, the grinding method includes sand grinding; the median particle size D50 of the powder obtained by sand grinding 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. The other unlisted values within the numerical range are equally applicable.

[0047] The present invention does not specifically limit parameters such as the manner and time of sand grinding, as long as the median particle size D50 of the powder obtained by sand grinding is 0.6 μm - 1.5 μm. Generally speaking, controlling the sand grinding time to be 30 min - 180 min can achieve the technical effect that the median particle size D50 of the material obtained by sand grinding is 0.6 μm - 1.5 μm.

[0048] Grinding can further refine the particle size of the barium titanate powder. During the continuous refinement of its particle size, the specific surface area increases, which is beneficial for obtaining a dense high-dielectric barium titanate material in subsequent sintering. However, during the continuous refinement of the particle size, fine particles re-agglomerate under the influence of van der Waals forces, double-layer electrostatic forces, etc. Therefore, as a preferred technical solution, a dispersant is used during grinding to prevent the mutual aggregation of barium titanate powders. Therefore, carbon removal treatment needs to be carried out after grinding to remove the dispersant.

[0049] The present invention does not specifically limit the dosage and type of the dispersant, as long as the dispersion effect during grinding can be achieved.

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

[0051] The temperature of the carbon removal is 450°C - 800°C. For example, it can be 450°C, 500°C, 600°C, 700°C, or 800°C, but is not limited to the listed values. The other unlisted values within the numerical range are equally applicable.

[0052] The carbon discharging time is 8h - 18h. For example, it can be 8h, 10h, 12h, 15h, 16h or 18h, but is not limited to the listed values. The other unlisted values within the numerical range are equally applicable.

[0053] In some embodiments, water is used as the grinding medium for the sand grinding. Water has a good dispersion effect. During the sand grinding process, it adsorbs on the surface of solid particles, reducing the interfacial tension between liquid - liquid and solid - liquid, making the surface of the agglomerated solid particles easy to wet, and preventing the mutual agglomeration of fine particles. However, the residual moisture is not conducive to subsequent sintering.

[0054] In some embodiments, the carbon discharging treatment further includes drying before carbon discharging. The drying temperature is 80°C - 180°C, and the time is 6h - 18h.

[0055] The drying temperature is 80°C - 180°C. For example, it can be 80°C, 100°C, 120°C, 150°C, 160°C or 180°C, but is not limited to the listed values. The other unlisted values within the numerical range are equally 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. The other unlisted values within the numerical range are equally applicable.

[0057] In some embodiments, the method of the first crushing treatment includes depolymerization.

[0058] The carbon discharging treatment after grinding causes agglomeration of the barium titanate powder. In order to meet the requirements for the fine powder particle size during sintering and obtain a high - dielectric barium titanate material with uniform composition and density, it is necessary to depolymerize the agglomerated barium titanate powder through the first crushing treatment, so as to obtain barium titanate fine powder with a uniform particle size distribution, which is further beneficial to obtaining a high - dielectric barium titanate material with a relatively high dielectric constant.

[0059] Exemplarily, the depolymerization is carried out in a jet mill.

[0060] In some embodiments, in order to obtain barium titanate fine powder with a median particle size D50 satisfying 0.6μm - 1.5μm by a jet mill and reduce the operating pressure of the jet mill, the first crushing treatment includes sequentially performing coarse crushing by a jaw crusher, fine crushing by a roll crusher, and depolymerization by a jet mill. The "coarse crushing" and "fine crushing" here are relative concepts, that is, the average particle size of the material obtained by coarse crushing is larger than that of the material obtained by fine crushing.

[0061] In some embodiments, the heating rate during sintering is 2°C / min - 20°C / min. For example, it can be 2°C / min, 5°C / min, 10°C / min, 15°C / min, or 20°C / min, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable. Preferably, it is 2°C / min - 10°C / min.

[0062] In the present invention, the starting temperature of the sintering is room temperature. For example, it can be 15°C - 30°C, such as 15°C, 18°C, 20°C, 25°C, 28°C, or 30°C, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0063] In some embodiments, the maximum temperature of the sintering is 1200°C - 1500°C. For example, it can be 1200°C, 1250°C, 1300°C, 1350°C, 1400°C, 1450°C, or 1500°C, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

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

[0065] In some embodiments, the method of the second crushing treatment includes depolymerization. The median particle size D50 of the obtained 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. Other unlisted values within the numerical range are equally applicable.

[0066] Exemplarily, the depolymerization is carried out in an air classifier mill.

[0067] In some embodiments, in order to obtain a high-dielectric barium titanate material with a median particle size D50 satisfying 0.6 μm - 1.5 μm by an air classifier mill and reduce the operating pressure of the air classifier mill, the second crushing treatment includes coarse crushing by a jaw crusher, fine crushing by a pair-roll crusher, and depolymerization by an air classifier mill carried out in sequence. The "coarse crushing" and "fine crushing" herein are relative concepts, that is, the average particle size of the material obtained by coarse crushing is larger than that of the material obtained by 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 performing a pre-sintering treatment on the raw material powder to obtain a pre-sintered blank; and performing a raw material crushing treatment on the obtained pre-sintered blank.

[0069] The pre-sintering treatment causes the titanium source and the barium source to undergo a solid-phase reaction and removes moisture, volatile impurities, gases, and some organic substances present in the raw materials, thereby improving the purity of the prepared barium titanate powder; in addition, the barium titanate powder obtained by the pre-sintering treatment has a small sintering shrinkage rate and a greatly reduced porosity during subsequent sintering, which can promote the dense sintering and uniform refinement of the grain size of subsequent barium titanate, and is also beneficial to the improvement of 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 - 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, and the other unlisted values within the numerical range are equally applicable.

[0073] In some embodiments, the median particle size D50 of the raw material 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, and the other unlisted values within the numerical range are equally applicable.

[0074] In order to obtain a raw material powder with a median particle size D50 satisfying 0.8 μm - 3.5 μm, the mixing of the barium source and the titanium source is first carried out in a three-dimensional mixer, and then a jet mill is used to obtain a raw material powder with a median particle size D50 satisfying 0.8 μm - 3.5 μm.

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

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

[0077] In some embodiments, the heating rate during pre-sintering is 1°C / min - 20°C / min. For example, it can be 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. However, it is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable. Preferably, it is 5°C / min - 10°C / min.

[0078] In the present invention, the starting temperature of the pre-sintering is room temperature. For example, it can be 15°C - 30°C, such as 15°C, 18°C, 20°C, 25°C, 28°C, or 30°C. However, it is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0079] In some embodiments, the maximum temperature of the pre-sintering is 1150°C - 1350°C. For example, it can be 1150°C, 1200°C, 1250°C, 1300°C, or 1350°C. However, it is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0080] In some embodiments, the heat preservation time under the maximum temperature condition during the pre-sintering is 30 min - 180 min. For example, it can be 30 min, 50 min, 80 min, 100 min, 120 min, 150 min, 160 min, or 180 min. However, it is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0081] In some embodiments, the method for the raw material crushing treatment includes depolymerization.

[0082] Exemplarily, the depolymerization is carried out in a jet mill.

[0083] In some embodiments, in order to obtain barium titanate powder with a median particle size satisfying 0.8 μm - 3.5 μm by a jet mill and reduce the operating pressure of the jet mill, the raw material crushing treatment includes coarse crushing by a jaw crusher, fine crushing by a roll crusher, and depolymerization by a jet mill in sequence. The "coarse crushing" and "fine crushing" herein are relative concepts, that is, the average particle size of the material obtained by coarse crushing is larger than that of the material obtained by fine crushing.

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

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

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

[0087] For clearly illustrating the technical solution of the present invention, the normal temperature in the following specific embodiments is 25°C.

[0088] Example 1

[0089] This example provides a solid-phase sintering preparation method for a high-dielectric barium titanate material, and the solid-phase sintering preparation method includes:

[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 crush and mix the mixed raw materials through an air-flow crusher to obtain raw material powder with a median particle size D50 of 2 μm;

[0091] (2) Load the raw material powder into a crucible, vibrate and compact it on a vibrating table to make the material fully dense, then punch out exhaust ports with a uniform honeycomb arrangement, and place it in a muffle furnace for pre-sintering; the initial temperature during pre-sintering is normal temperature, the highest temperature is 1200°C, the heating rate is 8°C / min, keep the temperature at the highest temperature for heat preservation, and the heat preservation time is 120 min to obtain a pre-sintered blank;

[0092] (3) The pre-sintered blank is successively subjected to coarse crushing by a jaw crusher, fine crushing by a pair-roll crusher, and deflocculation by an air-flow crusher to obtain barium titanate powder with a median particle size D50 of 2 μm;

[0093] (4) Perform sanding treatment on the barium titanate powder, and the median particle size D50 of the powder obtained by sanding treatment is 1 μm;

[0094] (5) Dry the sanded powder at a temperature of 150°C for 10 h, and then remove carbon at a temperature of 600°C for 12 h; then subject the powder after carbon removal to coarse crushing by a crusher, fine crushing by a pair-roll crusher, and deflocculation by an air-flow crusher to obtain barium titanate fine powder with a median particle size D50 of 1 μm;

[0095] (6) Load the barium titanate fine powder into a crucible, place it on a vibrating table to vibrate and compact it to make the material fully dense, then punch out exhaust ports with a uniform honeycomb arrangement, and place it in a muffle furnace for sintering; the initial temperature of sintering is normal temperature, the highest temperature is 1400°C, the heating rate is 8°C / h, the heat preservation time is 2 h; after sintering, a sintered material is obtained;

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

[0097] The relationship diagram between the dielectric constant and temperature of the high-dielectric barium titanate material obtained in this example is as Figure 1 shown.

[0098] Example 2

[0099] This example provides a solid-phase sintering preparation method for a high-dielectric barium titanate material. The solid-phase sintering preparation method includes:

[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, and perform preliminary mixing in a three-dimensional mixer. Then, crush and mix the mixed raw materials with an air jet mill to obtain raw material powder with a median particle size D50 of 0.8 μm;

[0101] (2) Load the raw material powder into a crucible, vibrate and compact it on a vibrating compactor to make the material fully dense. Then, punch out exhaust holes with a uniform honeycomb arrangement and place it in a muffle furnace for pre-sintering; the initial temperature during pre-sintering is room temperature, the highest temperature is 1150 °C, the heating rate is 5 °C / min. When the highest temperature is reached, hold for 180 min to obtain a pre-sintered blank;

[0102] (3) The pre-sintered blank is successively subjected to coarse crushing by a jaw crusher, fine crushing by a roll crusher, and deflocculation by an air jet mill to obtain barium titanate powder with a median particle size D50 of 0.8 μm;

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

[0104] (5) The sanded powder is dried at 80 °C for 18 h, and then carbon is removed at 450 °C for 18 h; then the powder after carbon removal is successively subjected to coarse crushing by a crusher, fine crushing by a roll crusher, and deflocculation by an air jet mill to obtain barium titanate fine powder with a median particle size D50 of 0.6 μm;

[0105] (6) Load the barium titanate fine powder into a crucible, place it on a vibrating compactor to vibrate and compact it to make the material fully dense. Then, punch out exhaust holes with a uniform honeycomb arrangement and place it in a muffle furnace for sintering; the initial temperature of sintering is room temperature, the highest temperature is 1200 °C, the heating rate is 2 °C / h, and the holding time is 3 h; after sintering, a sintered material is obtained;

[0106] (7) The sintered material is successively subjected to coarse crushing by a jaw crusher, fine crushing by a roll crusher, and deflocculation 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-phase sintering preparation method for a high-dielectric barium titanate material. The solid-phase sintering preparation method includes:

[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. Conduct preliminary mixing in a three-dimensional mixer, and then crush and mix the mixed raw materials with an air jet mill to obtain raw material powder with a median particle size D50 of 3.5 μm.

[0110] (2) Load the raw material powder into a crucible, vibrate and compact it on a vibrating table to make the material fully dense. Then punch out exhaust ports arranged in a uniform honeycomb pattern and place it in a muffle furnace for pre-sintering. The initial temperature during pre-sintering is room temperature, the maximum temperature is 1350 °C, the heating rate is 10 °C / min. When the temperature rises to the maximum temperature, hold for 30 min to obtain a pre-sintered blank.

[0111] (3) The pre-sintered blank is successively subjected to coarse crushing by a jaw crusher, fine crushing by a pair-roll crusher, and depolymerization 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 is subjected to sanding treatment, and the median particle size D50 of the powder obtained by sanding treatment is 1.5 μm.

[0113] (5) The sanded powder is dried at a temperature of 180 °C for 6 h, and then carbon is removed at a temperature of 800 °C for 8 h. Then the powder after carbon removal is successively subjected to coarse crushing by a crusher, fine crushing by a pair-roll crusher, and depolymerization by an air jet mill to obtain barium titanate fine powder with a median particle size D50 of 1.5 μm.

[0114] (6) Load the barium titanate fine powder into a crucible, place it on a vibrating table and vibrate and compact it to make the material fully dense. Then punch out exhaust ports arranged in a uniform honeycomb pattern and place it in a muffle furnace for sintering. The initial temperature of sintering is room temperature, the maximum temperature is 1500 °C, the heating rate is 10 °C / h, and the holding time is 0.5 h. After sintering, a sintered material is obtained.

[0115] (7) The sintered material is successively subjected to coarse crushing by a jaw crusher, fine crushing by a pair-roll crusher, and depolymerization 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-phase sintering preparation method for a high-dielectric barium titanate material. Except that the molar ratio of barium carbonate to titanium dioxide is 0.990:1, the rest are the same as in Example 1.

[0118] Example 5

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

[0120] Embodiment 6

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

[0122] Embodiment 7

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

[0124] Embodiment 8

[0125] This embodiment provides a solid-phase sintering preparation method for high-dielectric barium titanate materials. Except that drying is not carried out, the rest are the same as in Embodiment 1.

[0126] Comparative Example 1

[0127] This comparative example provides a solid-phase sintering preparation method for barium titanate materials. The solid-phase sintering preparation method includes:

[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. Conduct preliminary mixing in a three-dimensional mixer, and then crush and mix the mixed raw materials through an air jet mill to obtain raw material powder with a median particle size D50 of 2 μm;

[0129] (2) Load the raw material powder into a sagger, vibrate and compact it on a vibrating table to make the material fully dense. Then punch out exhaust holes with a uniform honeycomb arrangement and place it in a muffle furnace for pre-sintering; the initial temperature during pre-sintering is room temperature, the maximum temperature is 1200 °C, the heating rate is 8 °C / min. When heating to the maximum temperature, hold for 120 min to obtain a pre-sintered blank;

[0130] (3) The pre-sintered blank is successively subjected to coarse crushing by a jaw crusher, fine crushing by a pair-roll crusher, and depolymerization by an air jet mill to obtain barium titanate powder with a median particle size D50 of 2 μm;

[0131] (4) Dry the barium titanate powder at a temperature of 150 °C for 10 h, and then dehydrate it at a temperature of 600 °C for 12 h; then conduct coarse crushing of the dehydrated powder by a crusher, fine crushing by a pair-roll crusher, and depolymerization by an air jet mill to obtain barium titanate fine powder with a median particle size D50 of 2 μm;

[0132] (5) Load the barium titanate fine powder into a sagger, place it on a vibrating table to vibrate and compact it to make the material fully dense, then punch out exhaust holes arranged in a uniform honeycomb pattern, and put it into a muffle furnace for sintering; the initial temperature of sintering is room temperature, the highest temperature is 1400 °C, the heating rate is 8 °C / h, and the holding time is 2 h; after sintering, a sintered material is obtained.

[0133] (6) The sintered material is successively subjected to coarse crushing by a jaw crusher, fine crushing by a pair-roll crusher, and depolymerization by an air-flow pulverizer 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-phase sintering preparation method for a barium titanate material, and the solid-phase sintering preparation method includes:

[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 crush and mix the mixed raw materials by an air-flow pulverizer to obtain raw material powder with a median particle size D50 of 2 μm.

[0137] (2) Load the raw material powder into a sagger, place it on a vibrating table to vibrate and compact it to make the material fully dense, then punch out exhaust holes arranged in a uniform honeycomb pattern, and put it into a muffle furnace for pre-sintering; the initial temperature during pre-sintering is room temperature, the highest temperature is 1200 °C, the heating rate is 8 °C / min, hold for heat preservation when the highest temperature is reached, and the holding time is 120 min to obtain a pre-sintered blank.

[0138] (3) The pre-sintered blank is successively subjected to coarse crushing by a jaw crusher, fine crushing by a pair-roll crusher, and depolymerization by an air-flow pulverizer to obtain barium titanate powder with a median particle size D50 of 2 μm.

[0139] (4) Perform sanding treatment on the barium titanate powder, and the median particle size D50 of the powder obtained by sanding treatment is 1 μm.

[0140] (5) Load the powder obtained by sanding treatment into a sagger, place it on a vibrating table to vibrate and compact it to make the material fully dense, then punch out exhaust holes arranged in a uniform honeycomb pattern, and put it into a muffle furnace for sintering; the initial temperature of sintering is room temperature, the highest temperature is 1400 °C, the heating rate is 8 °C / h, and the holding time is 2 h; after sintering, a sintered material is obtained.

[0141] (6) The sintered material is successively subjected to coarse crushing by a jaw crusher, fine crushing by a pair-roll crusher, and depolymerization by an air-flow pulverizer 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 from the above-mentioned embodiments and the barium titanate material obtained from the comparative example were pressed into disc samples with a diameter of 30 mm and a thickness of 4 mm under a pressure of 20 MPa, and the dielectric properties of the disc samples were tested in the temperature range of -55°C to 200°C. The results are shown in Table 1.

[0144] Table 1

[0145]

[0146]

[0147] In summary, through grinding, carbon removal treatment and the first crushing treatment, the present invention makes the particle size of the barium titanate fine powder small and uniform, and can form a uniform and dense microstructure during subsequent sintering, improving the problems of low purity of barium titanate, inability to meet the requirements of powder particle size and low dielectric constant caused by the traditional solid-phase sintering method. The dielectric constant of the obtained high-dielectric barium titanate material can reach more than 3000 F / m at -55°C, more than 3000 F / m at 25°C, and the peak value at the Curie point can reach more than 10000 F / m, with a low dielectric loss.

[0148] The applicant declares that the above description is only the specific implementation manner 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 by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A solid-phase sintering preparation method of a high-dielectric barium titanate material, characterized in that, The solid-phase sintering preparation method includes the following steps: The barium titanate powder is successively ground, carbon-removed, and first crushed to obtain fine barium titanate powder; the fine barium titanate powder is successively sintered and second crushed to obtain the high-dielectric barium titanate material; The particle size of the fine barium titanate powder obtained by the first crushing treatment is the same as that of the powder obtained by grinding.

2. The solid-phase sintering preparation method according to claim 1, wherein 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 fine barium titanate powder is 0.6 μm - 1.5 μm.

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

4. The solid-phase sintering preparation method according to claim 1, characterized in that The heating rate of the sintering is 2°C / min - 20°C / min; And / or, the highest temperature of the sintering is 1200°C - 1500°C; And / or, the holding time at the highest temperature during the sintering is 0.5 h - 3 h.

5. The solid-phase sintering preparation method according to claim 1, wherein The method of the second crushing treatment includes depolymerization, and the median particle size D50 of the obtained high-dielectric barium titanate material is 0.6 μm - 1.5 μm.

6. The solid-phase sintering preparation method according to any one of claims 1-5, characterized in that, The barium titanate powder is prepared by the following preparation method: mixing a barium source and a titanium source to obtain a raw material powder; then performing a pre-sintering treatment on the raw material powder to obtain a pre-sintered blank; and performing a raw material crushing treatment on the obtained pre-sintered blank.

7. The solid-phase 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 0.8 μm - 3.5 μm.

8. The solid-phase sintering preparation method according to claim 6 or 7, characterized in that, The heating rate of the pre-sintering is 1°C / min - 20°C / min; And / or, the highest temperature of the pre-sintering is 1150°C - 1350°C; And / or, the holding time at the highest temperature during the pre-sintering is 30 min - 180 min; And / or, the method of the raw material crushing treatment includes depolymerization.

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

10. Application of a high-dielectric barium titanate material, characterized in that, The high-dielectric barium titanate material is used for piezoelectric devices or ferroelectric devices; The high-dielectric barium titanate material is the high-dielectric barium titanate material prepared by the solid-phase 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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