阅读说明：本技术 一种BaTiO3微晶粉体的制备方法 (BaTiO3Preparation method of microcrystalline powder ) 是由 吕丹亚 张忠量 吴康 叶舟 靳维维 岳巧玉 马通 于 2021-06-17 设计创作，主要内容包括：本发明公开了一种BaTiO-3微晶粉体的制备方法,具体涉及一种具有(111)取向的BaTiO-3微晶粉体的制备方法,首先通过传统固相法,合成了纯的高结晶度的四方BaTiO-3粉体。这种固相法合成的BaTiO-3粉体将作为熔盐法合成片状Ba-6Ti-(17)O-(40)粉体的原料粉体。合成的片状Ba-6Ti-(17)O-(40)粉体沿(001)方向择优生长。Ba-6Ti-(17)O-(40)为前驱体,制备片状BaTiO3粉体具有最高的纵横比(直径10～20μm,厚度<1.5μm)。此外,OPL-XRD分析显示,BaTiO-3沿(111)面择优生长。本发明提供了一种可大量制备(111)-BaTiO-3微晶粉体的新途径。(The invention discloses BaTiO 3 A preparation method of microcrystalline powder, in particular to a BaTiO with (111) orientation 3 The preparation method of the microcrystalline powder comprises the steps of firstly synthesizing pure tetragonal BaTiO with high crystallinity by a traditional solid phase method 3 And (3) powder. BaTiO synthesized by the solid phase method 3 The powder is used as molten salt method to synthesize flake Ba 6 Ti 17 O 40 A raw material powder of the powder. Synthesized flake Ba 6 Ti 17 O 40 The powder preferentially grows along the (001) direction. Ba 6 Ti 17 O 40 Is used as a precursor, and the prepared flaky BaTiO3 powder has the highest aspect ratio (the diameter is 10-20 mu m, and the thickness is 10-20 mu m)<1.5 μm). In addition, OPL-XRD analysis showed BaTiO 3 Preferentially growing along the (111) plane. The invention provides a method for preparing (111) -BaTiO in large quantity 3 A new approach of microcrystalline powder.)

1. BaTiO₃The preparation method of the microcrystalline powder is characterized in that,

firstly, synthesizing pure high-crystallinity tetragonal BaTiO by a traditional solid phase method₃Powder of BaTiO, and a process for producing the same₃Synthesizing flaky Ba from powder by molten salt method₆Ti₁₇O₄₀Powder and then flake-like Ba₆Ti₁₇O₄₀Preparing flaky BaTiO serving as a precursor₃The microcrystalline powder comprises the following specific steps:

(1) synthesis of tetragonal BaTiO₃Powder: with BaCO₃And TiO₂As a raw material, according to BaTiO₃Chemical raw materials are weighed according to the stoichiometric proportion, ball-milled and mixed for 12 hours, then dried, and synthesized into equiaxial BaTiO by the traditional solid phase method under the heat treatment condition of 1350 ℃ and heat preservation for 3 hours₃Powder; and carrying out secondary ball milling to refine BaTiO₃Powder;

(2) preparation of flake-form (001) -Ba₆Ti₁₇O₄₀Powder: firstly, solid-phase synthesis of BaTiO₃Powder and TiO₂Mixing, ball milling and mixing for 12h, wherein BaTiO₃And TiO₂In a molar ratio of 6: 9; then adding NaCl molten salt with the same mass as the oxide raw material, continuously ball-milling, discharging and drying at 80 ℃; sealing the dried powder into a crucible, firstly melting NaCl molten salt to a molten state at 800 ℃ for 1h, and heating at the speed of 1 ℃/min; then, the temperature is continuously raised to 1130-1170 ℃, the temperature is kept for 1 to 5 hours, and the temperature raising and lowering speed is 5 ℃/min; adding an excess of BaTiO₃Preventing formation of impurity Ba₄Ti₁₃O₃₀After heat treatment, the sample is in a hard block shape, and is put into distilled water to be boiled, and the sample is stirred by a glass rod and subjected to ultrasonic means, so that the molten salt is gradually dissolved, and the block is gradually crushed; then repeatedly washing with boiling distilled water for several times, and drying at 120 ℃;

(3) preparation of (111) -BaTiO₃Flaky powder: is composed ofAvoid Ba₆Ti₁₇O₄₀The flaky shape of the powder is destroyed, and the molar ratio of Ba to Ba is 1:11₆Ti₁₇O₄₀With BaTiO₃Mixing by adopting a magnetic stirring mode; finally, placing the dried mixture into a closed alumina crucible for heat treatment, wherein the heat treatment condition is that the temperature is increased to 800 ℃ at the speed of 1 ℃/min, the temperature is kept for 1h, then the temperature is kept for 3-7h at the temperature of 1130-1190 ℃, and the temperature increasing and decreasing speed is 5 ℃/min; after heat treatment, putting the mixture into distilled water for boiling, stirring the mixture by a glass rod and carrying out ultrasonic means to gradually dissolve the molten salt and gradually crush the blocks; then repeatedly washing with boiling distilled water for several times, and drying at 120 deg.C.

Technical Field

The invention relates to BaTiO₃A preparation method of microcrystalline powder, in particular to a BaTiO with (111) orientation₃A preparation process of microcrystalline powder, belonging to the technical field of functional ceramic materials.

Background

Non-equiaxed BaTiO with tetragonal perovskite structure₃Has high chemical stability and good piezoelectric performance, and is always used as one of the very important templates for preparing perovskite structure textured ceramics. However, the perovskite system has a symmetrical crystal structure, so that the perovskite system usually develops into an equiaxed grain morphology, and therefore, the traditional solid phase method is difficult to synthesize the anisotropic morphology. Nanometer size spherical, cubic and dendritic BaTiO₃Powders have been synthesized by hydrothermal methods. Micron-sized (001) oriented BaTiO₃The fibers are synthesized by ion exchange reactions occurring in molten salt processes and hydrothermal processes. Millimeter size (-1.0 mm)²X 0.4mm) (001) oriented BaTiO₃The plate-shaped single crystal was successfully produced by the Remeika process using the molten salt method. However, the use of such large-sized powder as a template leads to deterioration of material compactness, coarsening of microstructure, and reduction of mechanical strength. Although the hot pressing method can increase the compactness of the ceramic, the cost of hot pressing and the excessive PbO make BaTiO₃Losing commercial potential for ceramic materials for the template. Therefore, there is a high necessity to find an effective method for preparing BaTiO having a high anisotropy and having the same or similar matrix structure as that of the matrix₃The template is used for solving the problems in the experiment.

Disclosure of Invention

The invention provides a method for mass production of a catalyst having a structure of (111) -BaTiO₃The new approach of the microcrystalline powder comprises the following specific steps:

firstly, pure tetragonal BaTiO with high crystallinity is synthesized by a traditional solid phase method₃Powder of BaTiO, and a process for producing the same₃Synthesizing flaky Ba from powder by molten salt method₆Ti₁₇O₄₀Powder and then flake-like Ba₆Ti₁₇O₄₀Is frontDriving body, preparing sheet BaTiO₃And (3) microcrystalline powder.

Raw materials: analytically pure BaCO₃、TiO₂Salt assistant NaCl

The method comprises the following specific steps:

(1) synthesize tetragonal BaTiO₃Powder: in vivo BaCO₃And TiO₂As a raw material, according to BaTiO₃Chemical raw materials are weighed according to the stoichiometric proportion, ball-milled and mixed for 12 hours, then dried, and synthesized into equiaxial BaTiO by the traditional solid phase method under the heat treatment condition of 1350 ℃ and heat preservation for 3 hours₃Powder; and carrying out secondary ball milling to refine BaTiO₃And (3) powder.

(2) Preparation of flake-form (001) -Ba₆Ti₁₇O₄₀Powder: in order to mix the reactants thoroughly, solid-phase synthesized BaTiO is firstly used₃Powder and TiO₂Mixing, ball milling and mixing for 12h, wherein BaTiO₃And TiO₂In a molar ratio of 6: 9; then adding NaCl molten salt with the same mass as the oxide raw material, continuously ball-milling, discharging and drying at 80 ℃; sealing the dried powder into a crucible, firstly melting NaCl molten salt to a molten state at 800 ℃ for 1h, and heating at the speed of 1 ℃/min; then, the temperature is continuously raised to 1130-1170 ℃, the temperature is kept for 1-5h, and the temperature raising and lowering speed is 5 ℃/min. Adding an excess of BaTiO₃Is to prevent the formation of impurity Ba₄Ti₁₃O₃₀. After heat treatment, the sample is in a hard block shape, and needs to be put into distilled water for boiling, and the sample is stirred by a glass rod and subjected to ultrasonic means, so that the molten salt is gradually dissolved, and the block is gradually crushed. Then repeatedly washing with boiling distilled water for several times, and drying at 120 deg.C.

(3) Preparation of (111) -BaTiO₃Flaky powder: to avoid Ba₆Ti₁₇O₄₀The flaky shape of the powder is destroyed, and the molar ratio of Ba to Ba is 1:11₆Ti₁₇O₄₀With BaTiO₃Mixing by magnetic stirring. Since the salt is insoluble in alcohol, the salt needs to be added after grinding and pulverizing in the second step. Finally, placing the dried mixture into a closed alumina crucible for heat treatment, wherein the heat treatment condition is that the temperature is increased to 800 ℃ at the speed of 1 ℃/min, the temperature is kept for 1h, and then the temperature is 1130 ∞1190 deg.C, keeping the temperature for 3-7h, and the temperature rising and reducing rate is 5 deg.C/min. After heat treatment, the mixture is put into distilled water to be boiled and stirred by a glass rod and subjected to ultrasonic means, so that the molten salt is gradually dissolved, and the blocks are gradually crushed. Then repeatedly washing with boiling distilled water for several times, and drying at 120 deg.C.

Advantageous effects

Compared with the prior art, the invention has the following main advantages:

the method has the advantages that firstly, the process flow is simple, the repeatability is good, only three raw materials are needed, and the used raw materials are common industrial raw materials, are low in price and can be prepared in large quantities;

secondly, toxic organic metal compounds are not used in the preparation, toxic additional products are not generated, and the environmental requirements are met;

thirdly, the application range is wide. As a ferroelectric material with wide application, (111) -BaTiO₃The flaky powder can be widely applied to the fields of ceramic capacitors, piezoelectric ceramics, novel thermosensitive materials, dielectric materials, magnetic materials, optical materials and the like.

Of course, it is not necessary for any one product in which the present invention is practiced to achieve all of the above-described technical effects simultaneously.

Drawings

FIG. 1 shows the product A (tetragonal BaTiO) of example 1 of the present invention₃Powder) with PDF standard card (JCPDS 05-0626);

FIG. 2(a) shows the product B (Ba) in example 1 of the present invention₆Ti₁₇O₄₀) SEM photograph of (1), FIG. 2(b) X-ray diffraction pattern;

FIG. 3(a) shows the product C (BaTiO) obtained in example 1 of the present invention₃Powder) and fig. 3(b) is an X-ray diffraction pattern.

Detailed Description

The invention will be further described and understood with reference to the following drawings and specific examples, but the invention is not limited to the following examples.

In order to detect the preferred growth direction of the material, an oriented particle layer XRD test technology (OPL-XRD) is adopted, which has special requirements on the preparation of a sample, and mainly comprises the steps of dispersing particle powder into a solvent, and then casting the particle powder onto a glass substrate to prepare a test sample, wherein the selected solvent is a mixed solvent of ethanol and 2-butanone.

Example 1:

raw materials: analytically pure BaCO₃、TiO₂Salt assistant NaCl

The method comprises the following specific steps:

(1) synthesize tetragonal BaTiO₃Powder: with BaCO₃And TiO₂As a raw material, according to BaTiO₃Chemical raw materials are weighed according to the stoichiometric proportion, ball-milled and mixed for 12 hours, then dried, and synthesized into equiaxial BaTiO by the traditional solid phase method under the heat treatment condition of 1350 ℃ and heat preservation for 3 hours₃Powder; and carrying out secondary ball milling to refine BaTiO₃And (5) obtaining powder, and finally obtaining a product A.

Product A (tetragonal BaTiO)₃Powder) and PDF standard card (JCPDS 05-0626) as shown in fig. 1.

From FIG. 1, it was found that BaTiO synthesized₃All diffraction peaks of XRD pattern of the powder are equal to the tetragonal BaTiO of standard PDF pattern (JCPDS 05-0626)₃The diffraction peaks are completely coincident, which shows that pure tetragonal BaTiO with high crystallinity is synthesized by the traditional solid phase method at 1350 ℃ for 3h₃And (3) powder. BaTiO synthesized by the solid phase method₃The powder is used as molten salt method to synthesize precursor flake Ba₆Ti₁₇O₄₀A raw material powder of the powder.

(2) Preparation of flake-form (001) Ba₆Ti₁₇O₄₀Powder: in order to mix the reactants thoroughly, solid-phase synthesized BaTiO is firstly used₃Powder and TiO₂Mixing, ball milling and mixing for 12h, wherein BaTiO₃And TiO₂In a molar ratio of 6: 9; then adding NaCl molten salt with the same mass as the oxide raw material, continuously ball-milling, discharging and drying at 80 ℃; sealing the dried powder into a crucible, firstly melting NaCl molten salt to a molten state at 800 ℃ for 1h, and heating at the speed of 1 ℃/min; then the temperature is continuously increased to 1150 ℃, the temperature is kept for 3h, and the temperature increasing and decreasing speed is 5 ℃/min. Adding an excess of BaTiO₃Is to prevent the formation of impurity Ba₄Ti₁₃O₃₀. After heat treatment, the sample is in a hard block shape, and needs to be put into distilled water for boiling, and the sample is stirred by a glass rod and subjected to ultrasonic means, so that the molten salt is gradually dissolved, and the block is gradually crushed. Then repeatedly washing the mixture by boiling distilled water for several times, and drying the mixture at 120 ℃ to obtain a product B.

FIG. 2(a) shows a product B (Ba)₆Ti₁₇O₄₀) The SEM photograph of (a) is an X-ray diffraction pattern.

As seen from the SEM image in FIG. 2(a), when the heat treatment temperature was 1150 ℃ and the incubation time was 3 hours, the flaky Ba was observed₆Ti₁₇O₄₀The particles are large and uniform in size (roughly 10-20 μm in diameter, 0.5-1 μm in thickness, about 20-40 in aspect ratio, and preferably anisotropic in flake-like Ba, "Cast" and "no-Cast₆Ti₁₇O₄₀The XRD pattern of the powder (heat treatment conditions: 1150 ℃ C., heat preservation time 3h) is shown in FIG. 2 (b). The terms "Cast" and "no-Cast" are used to distinguish between powders that are Cast deposited on a glass substrate and powders that have not undergone any processing. Ba after "Cast₆Ti₁₇O₄₀The diffraction peak intensities of the powder particles (006) and (008) are obviously increased, which indicates that the powder particles preferentially grow along the (001) direction. All major diffraction peaks were consistent with the standard PDF (JCPDS35-817), indicating that Ba had been formed₆Ti₁₇O₄₀Powder

(3) Preparation of (111) BaTiO₃Flaky powder: to avoid Ba₆Ti₁₇O₄₀The flaky shape of the powder is destroyed, and the molar ratio of Ba to Ba is 1:11₆Ti₁₇O₄₀With BaTiO₃Mixing by magnetic stirring. Since the salt is insoluble in alcohol, the salt needs to be added after grinding and pulverizing in the second step. And finally, placing the dried mixture into a closed alumina crucible for heat treatment, wherein the heat treatment condition is that the temperature is increased to 800 ℃ at the speed of 1 ℃/min, the temperature is preserved for 1h, then the temperature is preserved for 5h at 1170 ℃, and the temperature increasing and decreasing speed is 5 ℃/min. After heat treatment, the mixture is put into distilled water to be boiled and stirred by a glass rod and subjected to ultrasonic means, so that the molten salt is gradually dissolved, and the blocks are gradually crushed. Then repeatedly washing with boiling distilled water for several times, and drying at 120 deg.C to obtain the productC。

FIG. 3(a) shows a product C (BaTiO)₃Powder) and (b) is an X-ray diffraction pattern.

From FIG. 3, it was found that when the heat treatment temperature was 1170 ℃ and the temperature was maintained for 5 hours, irregularly flaky BaTiO was formed₃The diameter of the powder particles is about 10-20 μm, and the thickness of the powder particles is<1.5 μm (aspect ratio of about 7 to 14) (FIG. 3 (a)). BaTiO 2₃The OPL-XRD pattern of the powder is shown in FIG. 3 (b). From the OPL-XRD picture, the BaTiO obtained by the second step of molten salt₃The strongest diffraction peak of the powder is the (111) peak, not the ordinary BaTiO₃Peak (110) of the powder. This result indicates that the synthesized flaky BaTiO₃The powder preferentially grows along the (111) direction. Furthermore, we compare FIG. 2(a) with FIG. 3(a), an important finding is that despite BaTiO₃Powder replaces Ba through topological reaction₆Ti₁₇O₄₀Obtained by but BaTiO₃Is relatively rough and Ba₆Ti₁₇O₄₀Is relatively smooth. This is mainly due to Ba₆Ti₁₇O₄₀The surface energy of the dense plane (001) plane is relatively low, and BaTiO₃(111) The surface energy of the face is higher than that of the (001) face, so that a relatively rough surface topography is formed. Further, BaTiO₃The rough surface likewise indicates plate-like BaTiO₃The powder may be a polycrystalline phase with a high degree of orientation rather than a single crystal.

Example 2

Raw materials: analytically pure BaCO₃、TiO₂Salt assistant NaCl

The method comprises the following specific steps:

(1) synthesize tetragonal BaTiO₃Powder: in vivo BaCO₃And TiO₂As a raw material, according to BaTiO₃Chemical raw materials are weighed according to the stoichiometric proportion, ball-milled and mixed for 12 hours, then dried, and synthesized into equiaxial BaTiO by the traditional solid phase method under the heat treatment condition of 1350 ℃ and heat preservation for 3 hours₃Powder; and carrying out secondary ball milling to refine BaTiO₃And (3) powder.

(2) Preparation of flake-form (001) Ba₆Ti₁₇O₄₀Powder: in order to mix the reactants thoroughly, the solid phase is first combinedFormed BaTiO₃Powder and TiO₂Mixing, ball milling and mixing for 12h, wherein BaTiO₃And TiO₂In a molar ratio of 6: 9; then adding NaCl molten salt with the same mass as the oxide raw material, continuously ball-milling, discharging and drying at 80 ℃; sealing the dried powder into a crucible, firstly melting NaCl molten salt to a molten state at 800 ℃ for 1h, and heating at the speed of 1 ℃/min; then, the temperature is continuously increased to 1130 ℃, the temperature is kept for 1h, and the temperature increasing and decreasing speed is 5 ℃/min. Adding an excess of BaTiO₃Is to prevent the formation of impurity Ba₄Ti₁₃O₃₀. After heat treatment, the sample is in a hard block shape, and needs to be put into distilled water for boiling, and the sample is stirred by a glass rod and subjected to ultrasonic means, so that the molten salt is gradually dissolved, and the block is gradually crushed. Then repeatedly washing with boiling distilled water for several times, and drying at 120 deg.C.

(3) Preparation of (111) BaTiO₃Flaky powder: to avoid Ba₆Ti₁₇O₄₀The flaky shape of the powder is destroyed, and the molar ratio of Ba to Ba is 1:11₆Ti₁₇O₄₀With BaTiO₃Mixing by magnetic stirring. Since the salt is insoluble in alcohol, the salt needs to be added after grinding and pulverizing in the second step. And finally, placing the dried mixture into a closed alumina crucible for heat treatment, wherein the heat treatment condition is that the temperature is increased to 800 ℃ at the speed of 1 ℃/min, the temperature is preserved for 1h, then the temperature is preserved for 7h at 1170 ℃, and the temperature increasing and decreasing speed is 5 ℃/min. After heat treatment, the mixture is put into distilled water to be boiled and stirred by a glass rod and subjected to ultrasonic means, so that the molten salt is gradually dissolved, and the blocks are gradually crushed. Then repeatedly washing with boiling distilled water for several times, and drying at 120 deg.C.

Example 3

Raw materials: analytically pure BaCO₃、TiO₂Salt assistant NaCl

The method comprises the following specific steps:

(1) synthesize tetragonal BaTiO₃Powder: in vivo BaCO₃And TiO₂As a raw material, according to BaTiO₃Chemical raw materials are weighed according to the stoichiometric proportion, ball-milled and mixed for 12 hours, then dried, and synthesized into equiaxial BaTiO by the traditional solid phase method under the heat treatment condition of 1350 ℃ and heat preservation for 3 hours₃Powder; and carrying out secondary ball milling to refine BaTiO₃And (3) powder.

(2) Preparation of flake-form (001) Ba₆Ti₁₇O₄₀Powder: in order to mix the reactants thoroughly, solid-phase synthesized BaTiO is firstly used₃Powder and TiO₂Mixing, ball milling and mixing for 12h, wherein BaTiO₃And TiO₂In a molar ratio of 6: 9; then adding NaCl molten salt with the same mass as the oxide raw material, continuously ball-milling, discharging and drying at 80 ℃; sealing the dried powder into a crucible, firstly melting NaCl molten salt to a molten state at 800 ℃ for 1h, and heating at the speed of 1 ℃/min; then, the temperature is continuously increased to 1130 ℃, the temperature is kept for 1h, and the temperature increasing and decreasing speed is 5 ℃/min. Adding an excess of BaTiO₃Is to prevent the formation of impurity Ba₄Ti₁₃O₃₀. After heat treatment, the sample is in a hard block shape, and needs to be put into distilled water for boiling, and the sample is stirred by a glass rod and subjected to ultrasonic means, so that the molten salt is gradually dissolved, and the block is gradually crushed. Then repeatedly washing with boiling distilled water for several times, and drying at 120 deg.C.

(3) Preparation of (111) BaTiO₃Flaky powder: to avoid Ba₆Ti₁₇O₄₀The flaky shape of the powder is destroyed, and the molar ratio of Ba to Ba is 1:11₆Ti₁₇O₄₀With BaTiO₃Mixing by magnetic stirring. Since the salt is insoluble in alcohol, the salt needs to be added after grinding and pulverizing in the second step. And finally, placing the dried mixture into a closed alumina crucible for heat treatment, wherein the heat treatment condition is that the temperature is increased to 800 ℃ at the speed of 1 ℃/min, the temperature is preserved for 1h, then the temperature is preserved for 3h at 1170 ℃, and the temperature increasing and decreasing speed is 5 ℃/min. After heat treatment, the mixture is put into distilled water to be boiled and stirred by a glass rod and subjected to ultrasonic means, so that the molten salt is gradually dissolved, and the blocks are gradually crushed. Then repeatedly washing with boiling distilled water for several times, and drying at 120 deg.C.

The test results of example 2 and example 3 are similar to the test results of example 1, and are not repeated herein.

While the foregoing description shows and describes several preferred embodiments of the present invention, it is to be understood that the invention is not limited to the forms disclosed herein, but is capable of use in various other combinations, modifications, and environments and is capable of changes or modifications within the scope of the invention as expressed in the appended claims.