A method for preparing a complete mosaic-like barium strontium titanate solid solution ceramic sheet

Abstract

The present application relates to a kind of preparation of complete mosaic-like barium strontium titanate solid solution ceramic sheet, which comprises the following steps: (1) two initial powders are mixed uniformly. After the stoichiometric ratio of nano barium titanate powder and nano strontium titanate powder is mechanically mixed by planetary ball mill for 24h, it is dried and ground to obtain the powder to be sintered;(2) the powder to be sintered is placed in graphite mold twice, the two powders are separated by two carbon paper, and pre-pressed in hand rotating tablet press and discharge plasma sintering furnace;(3) discharge plasma sintering is carried out, and appropriate sintering parameters are set, and sintering program is started, and after sintering, it is first rapidly cooled to a safe temperature 900 DEG C where grain growth is not easy, and then slowly cooled to 600 DEG C at 5 DEG C / min;(4) the sintered sample is placed in muffle furnace, and annealed at 800 DEG C for 10h, to obtain two relatively complete mosaic-like barium strontium titanate solid solution sheets.

Description

Technical Field

[0001] This invention relates to the field of ceramic material preparation technology, and in particular to a method for preparing complete mosaic-shaped barium strontium titanate solid solution ceramic sheets. Background Technology

[0002] In the preparation of bulk materials using spark plasma sintering (SPS) technology, traditional methods are limited to producing only a single sample per sintering cycle. This not only significantly reduces production efficiency but also makes it difficult to ensure consistency between different batches of sintered samples. To measure the electrical properties of ceramic materials, it is necessary to prepare metal electrodes and accurately calculate their area. However, ceramic materials are fragile during SPS sintering, making it difficult to obtain sufficiently large sample areas. This increases the difficulty of preparing and measuring metal electrodes, affecting the accuracy of electrode area calculations and consequently the precision of performance measurements. Therefore, developing a method capable of preparing multiple complete ceramic samples in a single SPS sintering cycle is crucial for improving preparation efficiency and material performance testing. Grain growth plays a decisive role in the material sintering process. It directly affects the microstructure and macroscopic properties of the sintered body by controlling grain size and distribution, and is key to achieving material densification and performance optimization. Traditionally, grain growth is considered to be achieved through atomic diffusion driven by interfacial energy. In recent years, research has revealed another novel growth mechanism during grain growth—ordered coalescence of nanocrystals—in which small grains act as basic units, undergoing ordered self-assembly to form unique mosaic structures. This discovery provides a new perspective on understanding grain growth. Nevertheless, our understanding of how to effectively prepare such ordered coalescence structures, their specific impact on material properties, and their mechanisms of action remains in its early stages and requires further in-depth research. Summary of the Invention

[0003] The purpose of this invention is to solve the above problems. This invention attempts to prepare mosaic-shaped barium strontium titanate solid solution ceramics by slow cooling through discharge plasma sintering. That is, by changing the ball milling conditions, sample loading method and SPS sintering procedure, two identical and relatively complete barium strontium titanate solid solution ceramics with easily measurable properties and special microstructures can be prepared at the same time.

[0004] Technical Solution: This invention proposes a method for preparing complete mosaic-shaped barium strontium titanate solid solution ceramic thin sheets, the method comprising the following steps:

[0005] (a) BaTiO3 nanopowder and SrTiO3 nanopowder were selected as the raw powder, two ZrO2 balls of different sizes were used as grinding balls, and anhydrous ethanol was used as the ball milling medium.

[0006] (b) Add the grinding balls, raw powder and grinding media from (a) into the grinding jar in a certain proportion, and perform ball milling according to the set grinding parameters;

[0007] (c) After ball milling, place the sample in a forced-air drying oven, dry it, grind it with a mortar and pestle, and sieve it through a 60-mesh sieve to obtain a ball-milled mixed powder sample for later use.

[0008] (d) Pour the mixed powder described in (c) into a graphite mold wrapped with a layer of carbon paper in two evenly portions. Place carbon paper between the column head and the powder, and between the powder particles. Perform the first pre-compression on the mold at a pressure of 2 MPa on a manual rotary tablet press for 5-10 minutes.

[0009] (e) Place the mold in a spark plasma sintering furnace and pre-press it for a second time at a pressure of 100 MPa for 5-10 min.

[0010] (f) Wrap the pre-pressed mold containing the powder block from (d) with carbon felt and place it in a spark plasma sintering furnace. Set the temperature, pressure and time of the sintering program and sinter. Monitor the sintering temperature in real time using infrared thermometry above 570℃.

[0011] (g) After sintering, the sample was placed in a muffle furnace for annealing to obtain two complete blocky mosaic-shaped barium strontium titanate solid solution ceramic samples.

[0012] (h) Polish the bulk sample obtained in (g) to a thickness of 0.5-0.6 mm, and plate electrodes on both sides of the sample to obtain the final sample with measurable performance.

[0013] Furthermore, in step (a), the particle size of the BaTiO3 powder is 30 nm, the particle size of the SrTiO3 powder is 55 nm, and the purity of both is greater than 99.5%. The diameters of the grinding balls are 5 mm and 3 mm, and the ratio of the number of the two types of grinding balls is 1:2.

[0014] Furthermore, in step (b), the certain proportion is V. 粉 :V 球 :V 介质 = 1:10:10, and the total volume of the three components is 1 / 2 of the volume of the ball mill jar. In step (b), the ball milling parameters are ball milling speed 250 rpm / min, ball milling time 24 h, and interval time 20 min.

[0015] Furthermore, in step (d), during the process of uniformly pouring the mixed powder into the mold twice, the mass of the mixed powder poured in each time is 0.61g. In step (d), the pressurization process ensures that the two ends of the column head are aligned, that is, the two sample powders are in the middle of the mold.

[0016] Furthermore, in step (f), the heating process in the sintering procedure is set with parameters according to actual needs, and the cooling process should first be rapidly reduced to a safe temperature of 900°C, where grains are unlikely to continue growing, at a rate of 100°C / min, and then slowly reduced to 600°C at a rate of 5°C / min.

[0017] Furthermore, in step (g), the annealing conditions are as follows: heating from room temperature to 800°C at a heating rate of 5°C / min, holding at that temperature for 10 hours, and then cooling in the furnace.

[0018] Furthermore, in step (h), the sandpaper used in the polishing process is greater than 2000 grit, and the error in polishing thickness is less than 0.002 mm.

[0019] Furthermore, in step (h), the electrode is made of silver paste, is circular in shape, and has an effective diameter of 5 mm.

[0020] Furthermore, in step (h), the electrode is heated to 650°C at a rate of 5°C / min, held for 30 min, and then cooled down in the furnace.

[0021] Furthermore, the present invention also proposes a mosaic-shaped barium strontium titanate solid solution ceramic sheet, which is prepared by any one of the methods described herein.

[0022] Beneficial effects: Compared with traditional technologies, the present invention has the following obvious and prominent substantive features and significant advantages:

[0023] 1. The ball milling method and conditions in this invention can mix the two powders uniformly without changing their initial particle size.

[0024] 2. The sample loading method in this invention can prepare two dense and relatively thin ceramic sheets in one step by SPS sintering, which reduces sintering cost and sintering time, saves sample grinding time, and ensures the consistency of the two samples.

[0025] 3. By optimizing the cooling process, this invention prepares a relatively complete ceramic sheet while preserving the high-temperature microstructure, which is beneficial for sample performance testing.

[0026] 4. The present invention can form a special microstructure when the SrTiO3 content is high, which is of guiding significance for studying the grain growth mechanism of ceramics.

[0027] 5. This invention can rapidly prepare relatively complete and dense barium strontium titanate solid solution ceramic sheets. Compared with existing technologies, this invention can prepare two relatively complete and dense thin ceramic sheets in one step, which can save costs, improve sintering efficiency, reduce sample polishing time, and facilitate performance testing. In addition, the samples sintered under certain mixing ratios also have a unique mosaic-like microstructure. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, without creative effort, other related structures not shown in the drawings can be derived from these drawings.

[0029] Figure 1 This is a flowchart of the process for preparing mosaic-shaped barium strontium titanate solid solution ceramic sheets using SPS according to the present invention;

[0030] Figure 2 This is a schematic diagram of the sample loading process in this invention;

[0031] Figure 3 This is an example of the sintering procedure for preparing mosaic-shaped barium strontium titanate solid solution ceramic sheets using SPS in this invention. Curves 1 and 2 have a heating rate of 100℃ / min and sintering temperatures of 1000℃ and 1100℃, respectively; curves 3 and 4 have a heating rate of 10℃ / min and sintering temperatures of 1000℃ and 1100℃, respectively. All four sintering procedures involve first rapidly cooling to a safe temperature (900℃), then slowly cooling (5℃ / min) to 600℃ to ensure sample integrity.

[0032] Figure 4 The dielectric constant temperature spectra of some samples prepared using this invention were measured at 10 kHz. The heating rate for sintering the samples was 100 °C / min, and the sintering temperature was 1100 °C. Specifically, the initial powder in curve 1 was a mixed powder with 10 mol% SrTiO3; the initial powder in curve 2 was a mixed powder with 20 mol% SrTiO3; the initial powder in curve 3 was a mixed powder with 30 mol% SrTiO3; the initial powder in curve 4 was a mixed powder with 40 mol% SrTiO3; and the initial powder in curve 5 was a mixed powder with 50 mol% SrTiO3.

[0033] Figure 5The dielectric loss temperature spectra of some samples prepared using this invention were measured at 10 kHz. The heating rate for sintering the samples was 100 °C / min, and the sintering temperature was 1100 °C. Specifically, the initial powder in curve 1 was a mixed powder with 10 mol% SrTiO3; the initial powder in curve 2 was a mixed powder with 20 mol% SrTiO3; the initial powder in curve 3 was a mixed powder with 30 mol% SrTiO3; the initial powder in curve 4 was a mixed powder with 40 mol% SrTiO3; and the initial powder in curve 5 was a mixed powder with 50 mol% SrTiO3.

[0034] Figure 6 This is a SEM image of the larger grains in a mosaic-shaped barium strontium titanate solid solution ceramic sheet obtained by sintering an initial powder with 50 mol% SrTiO3 at 10 °C / min to 1100 °C using the preparation method of this invention. The image clearly shows a unique microstructure in the sample, namely a mosaic structure formed by the ordered merging of large grains.

[0035] Figure 7 This is a SEM image of the smaller grains in a mosaic-shaped barium strontium titanate solid solution ceramic sheet obtained by sintering an initial powder with 40 mol% SrTiO3 at 100 °C / min to 1000 °C using the preparation method of this invention. The image shows a unique microstructure in the sample, where even the small grains exhibit a mosaic structure formed by ordered grain merging. Detailed Implementation

[0036] The above solution will be further described below with reference to specific embodiments. The preferred embodiments of the present invention are described in detail below:

[0037] like Figure 1 As shown, this invention proposes a method for preparing complete mosaic-shaped barium strontium titanate solid solution ceramic sheets, which includes the following steps:

[0038] (a) BaTiO3 nanopowder and SrTiO3 nanopowder were selected as the raw powder, two ZrO2 balls of different sizes were used as grinding balls, and anhydrous ethanol was used as the ball milling medium.

[0039] (b) Add the grinding balls, raw powder and grinding media from (a) into the grinding jar in a certain proportion, and perform ball milling according to the set grinding parameters;

[0040] (c) After ball milling, place the sample in a forced-air drying oven, dry it, grind it with a mortar and pestle, and sieve it through a 60-mesh sieve to obtain a ball-milled mixed powder sample for later use.

[0041] (d) Pour the mixed powder described in (c) into a graphite mold wrapped with a layer of carbon paper in two evenly portions. Place carbon paper between the column head and the powder, and between the powder particles. Perform the first pre-compression on the mold at a pressure of 2 MPa on a manual rotary tablet press for 5-10 minutes.

[0042] (e) Place the mold in a spark plasma sintering furnace and pre-press it for a second time at a pressure of 100 MPa for 5-10 min.

[0043] (f) Wrap the pre-pressed mold containing the powder block from (d) with carbon felt and place it in a spark plasma sintering furnace. Set the temperature, pressure and time of the sintering program and sinter. Monitor the sintering temperature in real time using infrared thermometry above 570℃.

[0044] (g) After sintering, the sample was placed in a muffle furnace for annealing to obtain two complete blocky mosaic-shaped barium strontium titanate solid solution ceramic samples.

[0045] (h) Polish the bulk sample obtained in (g) to a thickness of 0.5-0.6 mm, and plate electrodes on both sides of the sample to obtain the final sample with measurable performance.

[0046] Furthermore, in step (a), the particle size of the BaTiO3 powder is 30 nm, the particle size of the SrTiO3 powder is 55 nm, and the purity of both is greater than 99.5%. The diameters of the grinding balls are 5 mm and 3 mm, and the ratio of the number of the two types of grinding balls is 1:2.

[0047] Furthermore, in step (b), the certain proportion is V. 粉 :V 球 :V 介质 = 1:10:10, and the total volume of the three components is 1 / 2 of the volume of the ball mill jar. In step (b), the ball milling parameters are ball milling speed 250 rpm / min, ball milling time 24 h, and interval time 20 min.

[0048] Furthermore, in step (d), during the process of uniformly pouring the mixed powder into the mold twice, the mass of the mixed powder poured in each time is 0.61g. In step (d), the pressurization process ensures that the two ends of the column head are aligned, that is, the two sample powders are in the middle of the mold.

[0049] Furthermore, in step (f), the heating process in the sintering procedure is set with parameters according to actual needs, and the cooling process should first be rapidly reduced to a safe temperature of 900°C, where grains are unlikely to continue growing, at a rate of 100°C / min, and then slowly reduced to 600°C at a rate of 5°C / min.

[0050] Furthermore, in step (g), the annealing conditions are as follows: heating from room temperature to 800°C at a heating rate of 5°C / min, holding at that temperature for 10 hours, and then cooling in the furnace.

[0051] Furthermore, in step (h), the sandpaper used in the polishing process is greater than 2000 grit, and the error in polishing thickness is less than 0.002 mm.

[0052] Furthermore, in step (h), the electrode is made of silver paste, is circular in shape, and has an effective diameter of 5 mm.

[0053] Furthermore, in step (h), the electrode is heated to 650°C at a rate of 5°C / min, held for 30 min, and then cooled down in the furnace.

[0054] Furthermore, the present invention also proposes a mosaic-shaped barium strontium titanate solid solution ceramic sheet, which is prepared by any one of the methods described herein.

[0055] The preparation method provided in this embodiment allows for the one-time fabrication of multiple relatively complete, high-density barium strontium titanate solid solution ceramic sheets using SPS sintering. Furthermore, the ratio of strontium titanate to barium titanate can be controlled to prepare barium strontium titanate solid solution ceramic sheets with different compositions. In addition, the prepared ceramic sheets possess a unique mosaic-like microstructure, which is beneficial for the study of ceramic grain growth. This method is not limited to the preparation of barium strontium titanate ceramic materials and can also be applied to the preparation of other multiphase materials.

[0056] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made according to the purpose of the invention. Any changes, modifications, substitutions, combinations or simplifications made based on the spirit and principle of the technical solution of the present invention shall be equivalent substitutions. As long as they meet the purpose of the invention and do not deviate from the technical principles and inventive concept of the preparation method and application of strontium titanate-barium titanate ceramic materials of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. A method for preparing intact mosaic-shaped barium strontium titanate solid solution ceramic sheets, characterized in that, The method includes the following steps: (a) BaTiO3 nanopowder and SrTiO3 nanopowder were selected as the raw powder, two ZrO2 balls of different sizes were used as grinding balls, and anhydrous ethanol was used as the ball milling medium. (b) Add the grinding balls, raw powder and grinding media from (a) into the grinding jar in a certain proportion, and perform ball milling according to the set grinding parameters; (c) After ball milling, place the sample in a forced-air drying oven, dry it, grind it with a mortar and pestle, and sieve it through a 60-mesh sieve to obtain a ball-milled mixed powder sample for later use. (d) Pour the mixed powder described in (c) into a graphite mold wrapped with a layer of carbon paper in two equal parts. Place carbon paper between the column head and the powder and between the powders. Perform the first pre-compression on the mold with a pressure of 2 MPa on a manual rotary tablet press for 5-10 minutes. (e) Place the mold in a spark plasma sintering furnace and pre-press it for a second time at a pressure of 100 MPa for 5-10 min. (f) Wrap the pre-compressed mold containing the powder briquettes from (d) with carbon felt and place it in a spark plasma sintering furnace. Set the temperature, pressure, and time of the sintering program and perform sintering. Monitor the sintering temperature in real time using infrared thermography above 570℃. (g) After sintering, the sample was placed in a muffle furnace for annealing to obtain two complete blocky mosaic-shaped barium strontium titanate solid solution ceramic samples. (h) Polish the bulk sample obtained in (g) to a thickness of 0.5-0.6 mm, and plate electrodes on both sides of the sample to obtain the final sample with measurable performance; In step (a), the particle size of the BaTiO3 powder is 30 nm, the particle size of the SrTiO3 powder is 55 nm, and the purity of both is greater than 99.5%. The diameters of the grinding balls are 5 mm and 3 mm, and the ratio of the number of the two types of grinding balls is 1:

2. In step (b), the certain proportion is V 粉 V 球 V 介质 =1:10:10, and the total volume of the three is 1 / 2 of the volume of the ball milling jar. In step (b), the ball milling parameters are ball milling speed 250 rpm, ball milling time 24 h, and interval time 20 min. In step (d), during the process of pouring the mixed powder into the mold twice evenly, the mass of the mixed powder poured in each time is 0.61g. In step (d), the pressurization process ensures that the two ends of the column head are aligned, that is, the two sample powders are in the middle of the mold. In step (f), the heating process in the sintering procedure is set with parameters according to actual needs. The cooling process should first be rapidly reduced to a safe temperature of 900°C, where grains are unlikely to continue growing, at a rate of 100°C / min, and then slowly reduced to 600°C at a rate of 5°C / min.

2. The method for preparing complete mosaic-shaped barium strontium titanate solid solution ceramic sheets according to claim 1, characterized in that, In step (g), the annealing conditions are: heating from room temperature to 800°C at a heating rate of 5°C / min, holding at that temperature for 10 hours, and then cooling with the furnace.

3. The method for preparing complete mosaic-shaped barium strontium titanate solid solution ceramic sheets according to claim 1, characterized in that, In step (h), the sandpaper used in the polishing process is greater than 2000 grit, and the error in polishing thickness is less than 0.002 mm.

4. The method for preparing complete mosaic-shaped barium strontium titanate solid solution ceramic sheets according to claim 1, characterized in that, In step (h), the electrode is made of silver paste, is circular in shape, and has an effective diameter of 5 mm.

5. The method for preparing complete mosaic-shaped barium strontium titanate solid solution ceramic sheets according to claim 1, characterized in that, In step (h), the electrode firing conditions are: heating to 650°C at 5°C / min, holding at that temperature for 30 min, and then cooling down with the furnace.

6. A mosaic-shaped barium strontium titanate solid solution ceramic sheet, characterized in that, It is prepared by the method described in any one of claims 1 to 5.

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