JP2008247625A - Ceramic powder and method for manufacturing ceramic electronic part using the ceramic powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic powder capable of improving the dielectric constant of a dielectric layer of a ceramic electronic part and its reliability. <P>SOLUTION: The ceramic powder is substantially composed of a perovskite compound powder having a shape anisotropy. When the general formula of the perovskite compound powder is expressed as ABO<SB>3</SB>(wherein A is an A site element, B is a B site element and O is oxygen, respectively), the molar ratio A/B of the element A to the element B is smaller than 1.00. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ceramic powder used for a ceramic electronic component and a method for manufacturing a ceramic electronic component using the ceramic powder.

  In recent years, due to miniaturization of electronic devices, various ceramic electronic components used in electronic devices are also required to be miniaturized, and at the same time, compatibility with high performance is demanded.

  An example of the ceramic electronic component will be described using a multilayer ceramic capacitor. High performance for multilayer ceramic capacitors refers to high capacity, low loss, temperature characteristics, high reliability, etc. Among them, high capacity is an important factor for the development of next-generation products. The capacitance of the multilayer ceramic capacitor is determined by the thickness of the dielectric layer and the dielectric constant.

  As a first method for increasing the capacity, it is conceivable to reduce the thickness of the dielectric layer. However, when the dielectric layer is simply thinned, the insulation characteristics and reliability are significantly reduced. Because the insulation characteristics and reliability are determined by the grain boundary path length of the ceramic powder composing the dielectric layer existing between the electrode layers, the grain boundary path length of the ceramic powder is also shortened when the electrode layer is simply narrowed. Because. Therefore, in order to suppress the deterioration of the insulation characteristics and reliability, the ceramic powder used for the dielectric layer should be as fine as possible in the thickness direction and as large as possible in the transverse direction so that the ceramic powder particles between the electrode layers It is necessary to make the field path length as long as possible.

As a second method for increasing the capacity, a method of improving the dielectric constant of the dielectric layer can be considered. In general, a perovskite compound is used as a dielectric layer of a multilayer ceramic capacitor. For example, barium titanate (BaTiO ₃ ), which is a typical perovskite compound, has a property that the dielectric constant varies depending on the crystal orientation. In other words, if a dielectric layer having a high dielectric constant in the thickness direction can be produced, it is considered that the capacity can be increased. For that purpose, it is necessary to preferentially orient the orientation of barium titanate having a large relative dielectric constant in the thickness direction.

  From such a background, as a conventional ceramic powder, for example, when the perovskite compound is barium titanate, the development plane is a {111} plane and the aspect ratio is 2 or more. The ceramic powder which has is mentioned.

  However, since the ceramic powder alone has shape anisotropy, the ceramic powders are not densely packed even when fired, and a dense sintered body cannot be obtained. For this reason, in addition to the ceramic powder, an equiaxed ceramic powder having no shape anisotropy (non-shape anisotropy) is added. The two kinds of ceramic powders are mixed with a dispersion medium to form a slurry, the slurry is formed into a sheet, and further laminated and fired to obtain a ceramic electronic component.

For example, Patent Document 1 and Non-Patent Document 1 are known as prior art document information related to the present invention.
JP 2006-137657 A Tomoya Sato and Toshio Kimura, “Preparation of <111> Oriented BaTiO3 Using New Template Particles”, Proceedings of the 2006 Autumn Symposium, Japan Ceramic Society, 2006, p. 290

  As described above, since the non-shape anisotropic ceramic powder must be added to the conventional ceramic powder, the non-shape anisotropic ceramic powder grows during firing and has shape anisotropy. It will inhibit the grain growth of ceramic powder. Therefore, a sintered body having satisfactory shape anisotropy could not be obtained. Therefore, the ceramics manufactured using such conventional ceramic powder cannot increase the grain boundary path length of the dielectric layer, and the insulating property of the dielectric layer of the ceramic electronic component represented by the multilayer ceramic capacitor There was a problem that it was difficult to improve reliability.

  In addition, even when the ceramic powder has crystal anisotropy as well as shape anisotropy, the non-shape anisotropic ceramic powder grows during firing and has shape anisotropy and crystal anisotropy. It will inhibit the grain growth of the powder. Therefore, ceramics manufactured using such conventional ceramic powder cannot align the direction of large relative permittivity with the thickness direction of the dielectric layer, and the dielectric of ceramic electronic parts represented by multilayer ceramic capacitors There was a problem that it was difficult to improve the dielectric constant of the layer.

  On the other hand, when the non-shape anisotropic ceramic powder is not included, a dense sintered body cannot be obtained as described above, and the dielectric constant and insulation of the dielectric layer of the ceramic electronic component represented by the multilayer ceramic capacitor There was a problem that it was difficult to improve reliability.

  Therefore, an object of the present invention is to provide a ceramic powder that can improve the dielectric constant of a dielectric layer of a ceramic electronic component and can improve insulation and reliability.

In order to achieve this object, the present invention substantially comprises a perovskite compound powder having shape anisotropy, and the general formula of the perovskite compound powder is ABO ₃ (A is an element at A site, and B is a B site). And O represents oxygen element), the molar ratio A / B between the element A and the element B is less than 1.00.

  According to the ceramic powder of the present invention, a ceramic that can be densely sintered while having shape anisotropy can be obtained. As a result, the dielectric constant of the dielectric layer of the ceramic electronic component can be improved, and the insulation and reliability can be improved.

  Hereinafter, a ceramic powder of the present invention and a method for manufacturing a ceramic electronic component using the same will be described with reference to an embodiment and drawings.

  1 and 2 are step diagrams showing a ceramic powder of the present invention and a method of manufacturing a ceramic electronic component using the ceramic powder.

FIG. 3 shows a schematic diagram of the crystal structure of the perovskite compound. When the perovskite compound 300 is an oxide, it is generally expressed as ABO ₃ (A is an A site element 301, B is a B site element 302, and O is an oxygen element 303), and the ions of the A site element 301 and B The structure is formed in such a combination that the valences of the ions of the site element 302 are added to give an average trivalence. Note that the A site element 301 indicates a position surrounded by 12 O ions (12 coordination), and the B site element 302 indicates a position surrounded by 6 O ions (6 coordination). ).

Since the perovskite compound has a substantially isotropic crystal structure, it is difficult to obtain a powder having shape anisotropy even if the perovskite compound powder is directly produced. Therefore, as shown in FIGS. 1 and 2, a perovskite compound powder having shape anisotropy is prepared in two steps. That is, a compound having an anisotropic crystal structure is prepared as a precursor in the first step, and then ABO ₃ is prepared by adding and reacting the remaining components so as to become ABO _{3 in the} second step. As a method for producing the perovskite compound powder by the two steps, a molten salt method or a hydrothermal method is known. As an example, a method for producing ABO ₃ (A ion is divalent and B ion is tetravalent) by the molten salt method assuming that the precursor having an anisotropic crystal structure is A ₆ B ₁₇ O ₄₀ This will be described below.

As shown in FIG. 1, first, AO and BO ₂ as raw material powders are mixed, and A ₆ B ₁₇ O ₄₀ is prepared as a precursor by heat treatment (molten salt treatment) in the first step. Next, by adding AO which is a deficient component so as to become ABO _{3 in the} second step and heat treatment (molten salt treatment), a powder containing a perovskite compound having shape anisotropy as a main component can be obtained. The reaction formula is as shown in the following (Chemical Formula 1).

In the case of the above formula, since AO is added so that ABO ₃ has a stoichiometric composition in the second step, A / B which is the molar ratio of element A to element B in the produced ABO ₃ is 1 .00.

In the present invention, the molar ratio A / B between the element A and the element B in the ABO ₃ to be produced is set to less than 1.00. There are two methods. The first method is to reduce the amount of AO added in the second step of the above equation as shown in FIG. Thereby, it is possible to control A / B which is the molar ratio of the element A to the element B in the ABO ₃ to be produced to be less than 1.00.

As another method, as shown in FIG. 2, ABO ₃ produced in the second step of the above formula and having an A / B of 1.00 is acid-treated. That is, first, AO and BO ₂ which are raw material powders are mixed as in FIG. 1, and A ₆ B ₁₇ O ₄₀ is prepared as a precursor by heat treatment (molten salt treatment) in the first step. Next, by adding AO which is a deficient component so as to become ABO _{3 in the} second step and heat treatment (molten salt treatment), a powder containing a perovskite compound having shape anisotropy as a main component can be obtained. This powder, i.e., A / B is A component of the ABO ₃ by acid treatment ABO ₃ 1.00 is more preferentially removed. This is particularly remarkable when the element A contains an alkali metal element or an alkaline earth metal element. A / B can be controlled to be less than 1.00 by changing conditions such as the temperature, concentration, and time of acid treatment. Of course, the above two methods may be used in combination.

  The ceramic powder mainly composed of the perovskite compound powder having shape anisotropy obtained as described above will be referred to as a first ceramic powder 501. A predetermined amount of each of the first ceramic powder 501 and a second ceramic powder 502 mainly composed of the same type of perovskite compound powder as the non-formally anisotropic (eg spherical) perovskite compound powder was weighed and mixed. This is referred to as third ceramic powder 500.

  In addition to the third ceramic powder, a dispersion medium, a binder, a plasticizer, and the like are added to a predetermined container. This is mixed by a ball mill or a medium stirring mill to form a slurry. Note that the first ceramic powder and the second ceramic powder may be mixed in advance before adding the dispersion medium. The produced slurry is formed into a sheet on a carrier film by a doctor blade method or a die coating method, and dried to obtain a ceramic green sheet. The obtained ceramic green sheets are cut into a predetermined size, and a plurality of these are laminated.

  For example, when a multilayer ceramic capacitor as shown in a sectional view in FIG. 4 is manufactured as a ceramic electronic component, the ceramic green sheets and the internal electrode layers 402 are alternately stacked as the dielectric layer 401. The laminated body thus obtained is further pressurized as necessary to increase the density of the laminated body and cut into individual pieces. Then, firing is performed at a predetermined atmosphere and temperature. By chamfering as necessary, or by forming the external electrode 403, a multilayer ceramic capacitor is completed.

FIG. 5 (a) is a schematic cross-sectional view of a laminate produced using the third ceramic powder 500, and FIG. 5 (b) is a microstructure of ceramic particles in the sintered body when the laminate is fired. Each of the schematic cross-sectional views showing is shown. Now, comparing the element A at the A site and the element B at the B site constituting the perovskite compound, the diffusion rate of the element during firing is generally faster in the B element than in the A element. Since the element B in the perovskite compound, which is the main component of the first ceramic powder 501, is present in excess of the element A, grain growth during firing can be promoted. In such a case, since the grain growth rate of the first ceramic powder 501 is faster than that of the second ceramic powder 502, the first ceramic powder 501 can take in the second ceramic powder 502 and grow. The ceramic particles 503 in the sintered body reflect the shape of the first ceramic powder 501. That is, the grain boundary path length (FIG. 5A) of the ceramic particles 503 can be made longer. Thus, by setting A / B in ABO ₃ to be less than 1.00, a ceramic mainly composed of a perovskite compound that can be densely sintered while having shape anisotropy can be obtained. As a result, the dielectric constant of the dielectric layer of the ceramic electronic component represented by the multilayer ceramic capacitor can be improved, and the insulation and reliability can be improved.

  For comparison, FIG. 6A shows a schematic cross-sectional view of a laminate produced using a conventional ceramic powder, and FIG. 6B shows ceramic particles in the sintered body when the laminate is fired. Schematic cross-sectional views showing the fine structure of each are shown. The element B in the perovskite compound, which is the main component of the conventional ceramic powder 601, does not exist in excess of the element A, so that grain growth during firing cannot be promoted. In such a case, since the grain growth rate of the conventional ceramic powder 601 is not faster than that of the second ceramic powder 502, the conventional ceramic powder 601 cannot take in the second ceramic powder 502 and grow. It becomes difficult for the ceramic particles 603 in the sintered body to have shape anisotropy. As a result, the grain boundary path length of the ceramic particles 603 (FIG. 6A) becomes shorter than the grain boundary path length of the ceramic particles 503 (FIG. 5A).

Now, in the first ceramic powder, it is preferable that the element B of ABO ₃ which is a perovskite compound powder occupying the main component is mainly Ti. This is because Ti has a particularly fast diffusion rate during firing among the elements of the B site and can promote grain growth during firing.

Moreover, it is preferable that the element A of ABO ₃ that is a perovskite compound powder that occupies the main component of the first ceramic powder 501 contains at least one of Ca, Sr, and Ba as a main component. This is because grain growth during firing can be further promoted by a combination of Ca, Sr, Ba, which are alkaline earth metals having a low diffusion rate, and Ti, which has a high diffusion rate.

Moreover, it is preferable that the element A of ABO ₃ that is a perovskite compound powder that occupies the main component of the first ceramic powder has Ba as a main component, and the perovskite compound powder has BaTiO ₃ as a main component. This is because grain growth during firing can be further promoted by a combination of Ba, which is an alkaline earth metal having a low diffusion rate, and Ti, which has a high diffusion rate. The BaTiO ₃ is a ferroelectric and has a strong dielectric anisotropy, and the dielectric constant can be increased by orientation in a specific direction.

Further, A / B in ABO ₃ which is a perovskite compound powder occupying the main component of the first ceramic powder is particularly preferably 0.80 to 0.99 when the perovskite compound powder is BaTiO ₃ . In this case, the grain growth during firing can be promoted, and a sintered body having more shape anisotropy can be obtained. When A / B is smaller than 0.80, a large amount of impurity phase is contained in addition to the desired perovskite compound, and when A / B is larger than 0.99, the effect of promoting grain growth is small.

  Moreover, it is preferable that the relationship between the major axis and the minor axis of the perovskite compound powder occupying the main component of the first ceramic powder is such that the major axis / minor axis ≧ 2. Since it has shape anisotropy, the major axis direction can be arranged in the sheet forming direction at a shear rate during sheet forming described later.

  Moreover, it is preferable that the shape of the perovskite compound powder that occupies the main component of the first ceramic powder is needle-like. Since it has a needle shape, the major axis direction can be arranged in the sheet forming direction during sheet forming.

  Moreover, it is preferable that the shape of the perovskite compound powder which occupies the main component of the 1st ceramic powder is plate shape. Since it is plate-shaped, its major axis direction can be arranged in the sheet forming direction during sheet forming.

  Moreover, it is preferable that the perovskite compound powder which occupies the main component of the 1st ceramic powder has crystal anisotropy. A green sheet in which crystals of the perovskite compound powder having the shape anisotropy are oriented in a specific direction can be formed. This makes it possible to align the direction with a large relative dielectric constant in the thickness direction of the dielectric layer, and it is possible to improve the characteristics mainly of the dielectric constant of the dielectric layer of a ceramic electronic component typified by a multilayer ceramic capacitor.

Moreover, it is preferable that the perovskite compound powder which occupies the main component of the 1st ceramic powder is plate-shaped, and the development surface has preferential {111} plane orientation. As a result, the {111} planes of the perovskite compound powder can be aligned in the thickness direction of the dielectric layer, and the characteristics can be improved as compared to the non-oriented case. In particular, in the case of BaTiO _3, the {111} plane has no axial anisotropy, so that it is possible to improve the DC bias characteristics of a ceramic electronic component typified by a multilayer ceramic capacitor.

  It is also preferable that the development surface of the perovskite compound powder that occupies the main component of the first ceramic powder has a {110} plane orientation preferentially. As a result, the {110} plane of the perovskite compound powder can be aligned in the thickness direction of the dielectric layer, and characteristics such as an increase in the dielectric constant of the dielectric layer can be improved as compared with the non-oriented case.

  It is also preferable that the development surface of the perovskite compound powder that occupies the main component of the first ceramic powder has a {100} plane orientation preferentially. As a result, the {100} planes of the perovskite compound powder can be aligned in the thickness direction of the dielectric layer, and characteristics such as an increase in the dielectric constant of the dielectric layer can be improved as compared to the non-oriented case.

  In addition, as described above, the third ceramic powder to be put into the container at the time of manufacturing the ceramic electronic component is composed of the first ceramic powder and the second ceramic powder. A ceramic that can be sintered to a low temperature can be obtained. As a result, the dielectric constant of the dielectric layer of the ceramic electronic component can be improved and the reliability can be improved.

  In the second ceramic powder, the molar ratio A / B between the element A and the element B of the perovskite compound powder having no shape anisotropy is preferably larger than 1.00. This makes it possible to bring the ceramic containing the perovskite compound as a main component close to the stoichiometric composition, and to obtain a ceramic electronic component having stable characteristics. In addition, since the grain growth rate of the second ceramic powder can be suppressed, the grain growth of the first ceramic powder can be relatively promoted, and the powder can be more densely sintered while having more shape anisotropy. Ceramics that can be obtained can be obtained. As a result, the dielectric constant of the dielectric layer of the ceramic electronic component can be improved and the reliability can be improved.

In this embodiment, the precursor having an anisotropic crystal structure is A ₆ B ₁₇ O ₄₀ , but a compound having another composition may be used as long as the precursor has an anisotropic crystal structure. There may be. In addition, although the shortage component in the second step in (Chemical Formula 1) is AO which is an oxide containing A element, it may be a compound other than oxide such as carbonate such as ACO _3, and the shortage component is BO _2. Or a compound containing B element. The raw material powder may be in the form of a solution. Further, although the valence of the element A entering the A site is 2 and the valence of the element B entering the B site is 4, it is not limited to this, and any combination that forms a perovskite compound powder may be used. As the molten salt to be used, sodium chloride, potassium chloride, molybdenum oxide, potassium molybdate or the like is appropriately used. In the present embodiment, the molten salt treatment is used as the heat treatment when synthesizing the perovskite compound powder, but hydrothermal treatment may be used as described above. Further, in (Chemical Formula 1), it is more preferable to synthesize the perovskite compound powder in two steps, but it may be in one step, for example, it may be synthesized by a solid phase method using a needle-like or plate-like raw material powder. It is.

  In addition to the multilayer ceramic capacitor described above, ceramic electronic components that can be used with the ceramic powder produced by the ceramic electronic component manufacturing method of the present invention are represented by piezoelectric sensors, multilayer actuators, piezoelectric oscillators, and piezoelectric filters. Piezoelectric electronic components, multilayer inductors, magnetic electronic components typified by noise filters, bandpass filters, antenna switch modules, wireless run modules, high-frequency modules typified by Bluetooth modules, electronic components for thermistors, or composite components thereof Is mentioned.

  Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1
In Example 1, barium titanate (BaTiO ₃ ) powder having shape anisotropy and Ba / Ti ratio of less than 1.00 was synthesized by a two-stage molten salt method, and sintered using this. The body was made. The reaction formula for BaTiO ₃ synthesis is as shown in the following (Chemical Formula 2).

First, the precursor was synthesized in the first step. BaCO ₃ powder having an average particle diameter of 0.1 μm and TiO ₂ powder having an average particle diameter of 0.1 μm were prepared as raw material powders, and weighed so that the molar ratio was BaCO ₃ : TiO ₂ = 6: 17. Further, sodium chloride (NaCl) as a molten salt was weighed by the same weight as the total weight of the BaCO ₃ powder and TiO ₂ powder weighed earlier. These three kinds of powders were dry-mixed and put into an alumina crucible. The alumina crucible was covered and heat-treated at 1150 ° C. The crucible after the heat treatment was washed with pure water, and NaCl attached to the crucible was dissolved and removed. The mixture of the contents of these crucibles and pure water was stirred with a stirrer at 80 ° C., and then filtered to completely remove NaCl. The powder remaining on the filter paper was dried, and powder X-ray diffraction measurement using CuKα rays was performed. As a result, it was found that Ba ₆ Ti ₁₇ O _{40 as} a precursor was obtained.

Next, in the second step, BaTiO ₃ powder having a Ba / Ti ratio of less than 1.00 was synthesized. A Ba ₆ Ti ₁₇ O ₄₀ powder obtained in the first step and a BaCO ₃ powder having an average particle diameter of 0.1 μm were prepared as raw material powders, and Ba ₆ Ti ₁₇ O ₄₀ : BaCO ₃ = 1: (11− 17x). x was made into five types such that the Ba / Ti ratio (molar ratio) of the obtained BaTiO ₃ powder was 0.99, 0.95, 0.90, 0.80, 0.70 (sample number 2, 3, 4, 5, # 6). Further, as a comparative example, a sample in which x = 0, that is, the Ba / Ti ratio (molar ratio) of the obtained BaTiO ₃ powder was 1.00 was prepared (sample number # 1). Further, sodium chloride (NaCl) as a molten salt was weighed by the same weight as the total weight of the Ba ₆ Ti ₁₇ O ₄₀ powder and BaCO ₃ powder weighed earlier. These three types of powders were dry mixed and placed in an alumina crucible. The alumina crucible was covered and heat treated at 1050 ° C. The crucible after the heat treatment was washed with pure water, and NaCl attached to the crucible was dissolved and removed. The mixture of the contents of these crucibles and pure water was stirred with a stirrer at 80 ° C., and then filtered to completely remove NaCl. The powder remaining on the filter paper was dried, and powder X-ray diffraction measurement using CuKα rays was performed. The case where the main peak intensity of the impurity phase with respect to the main peak intensity of the BaTiO ₃ powder was less than 5% was marked with ◯, and the case where it was 5% or more was marked with x. Further, the powder was observed with an electron microscope, and when the ratio of the major axis / minor axis was 2 or more, the case where it was less than 2 and the case where it was less than 2 was marked as x.

The results are shown in (Table 1). When the A / B ratio (Ba / Ti ratio here) is 1.00 to 0.80 (sample numbers # 1, 2, _{3, 4,} 5), it is almost a BaTiO ₃ single phase and almost no impurity phase is observed. There wasn't. The ratio of major axis / minor axis of the powder was 2 or more.

As an example, sample number 3 (Example) having an A / B ratio of 0.95 is given and its details are displayed. FIG. 7 shows a powder X-ray diffraction spectrum of Sample No. 3. It was a BaTiO ₃ single phase and almost no impurity phase was observed. In addition, the number in a figure has shown the surface index of each peak position. The powder was dispersed in ethanol, and an alignment film was prepared by spin coating. FIG. 8 shows an X-ray diffraction spectrum of the surface of the alignment film. It can be seen that the peak intensity of the {111} plane is relatively increased as compared with FIG. FIG. 9 shows an electron micrograph of the powder of sample number 3. From the photograph, it was found that the BaTiO ₃ powder was plate-shaped. Moreover, it turned out that the development surface is a {111} surface also from the result of the above-mentioned X-ray-diffraction spectrum.

  Now, when the plate-like powder is observed with a microscope, there are two ways of viewing, that is, the development surface is mainly visible and the side surface is mainly visible. Those that can see the development surface have a small aspect ratio, and those that can see the side surface have a large aspect ratio. Therefore, 20 were selected in order of the powder having the larger aspect ratio from the 100 powders selected at random, and the major axis and minor axis were measured. The major axis was 20 to 40 μm and the minor axis was 2 to 10 μm. The average value of the 20 major axis / minor axis was about 6.

On the other hand, in sample number # 6 (comparative example) with an A / B ratio of 0.70, a peak of Ba ₄ Ti ₁₃ O ₃₀ as an impurity phase is clearly recognized in addition to BaTiO ₃ as shown in FIG. It had an intensity of 5% or more of the main peak of BaTiO ₃ .

Next, BaTiO ₃ powders of the sample numbers # 1, 2, _3, 4, and 5 were weighed 10% by weight as template powders. Further, spherical BaTiO ₃ powder having an average particle size of 0.3 μm was prepared, and 90% by weight was weighed as a matrix powder. The matrix powder and template powder were dry-mixed to obtain ceramic powder (sample numbers # 11, 12, 13, 14, and 15 respectively), and then charged into the prepared resin container. Further, 8% by weight of polyvinyl butyral resin as an organic binder and 100% by weight of the ceramic powder, 80% by weight of butyl acetate as a dispersion medium, and 6% by weight of dibutyl phthalate as a plasticizer were put into the resin container. In addition, 10 mmφ zirconia balls are put in the resin container in advance. This container was ball milled for 24 hours to prepare a slurry. After filtering this through a filter, a green sheet was formed by the doctor blade method. The gap of the doctor blade was 300 μm. About 20 produced green sheets were laminated, then cut to a size of about 12 mm □, debindered at 550 ° C., and fired at 1500 ° C. The sample after baking was about 10 mm × 10 mm × 0.6 mmt. The sintered body density was measured by the Archimedes method. Moreover, the X-ray-diffraction measurement of the surface of the sample was performed, and {111} plane orientation degree of the thickness direction was evaluated. The degree of orientation was determined by the Lotgering method (see Lottgering FK, J. Inorg. Nucl. Chem., 9 (1959), p. 113-123).

  The results are shown in (Table 2). 11 to 14 show X-ray diffraction spectra of sample numbers # 11, 12, 13, and 14, respectively. From FIG. 11, almost no {111} orientation was observed for sample number # 11 using powder (sample number # 1) with A / B of 1.00, and the degree of orientation was only 1%. On the other hand, from FIG. 12, with respect to Sample No. 12 using the template powder (Sample No. 2) with A / B of 0.99, an orientation tendency toward the {111} plane was observed, and the degree of orientation was 21%. . As shown in FIGS. 13 and 14, when a template powder having a smaller A / B was used, a result of increasing the degree of orientation was obtained. Note that the sintered body densities of sample numbers # 11, 12, 13, 14, and 15 all maintained 5.75 to 5.85, and a dense sintered body was obtained.

(Example 2)
A BaTiO ₃ powder (A / B1.00) of sample number # 1 prepared in Example 1 was prepared. Next, a nitric acid (HNO ₃ ) aqueous solution prepared to 3N was put into a beaker. The BaTiO ₃ powder was put into the beaker and stirred with a stirrer for 1 h, 3 h, and 6 h, respectively, to perform acid treatment. Thereafter, filtration was performed, and the powder remaining on the filter paper was dried. Samples that were stirred for 1 h, 3 h, and 6 h were designated as sample numbers 21, 22, and # 23, respectively. The Ba / Ti ratio of the three samples was measured by fluorescent X-ray analysis. The other evaluations were the same as in Example 1.

The results are shown in (Table 3) (results of # 1 are also shown). When the acid treatment time was lengthened, the A / B ratio tended to decrease. For sample numbers 21 and 22, no impurity phase was observed in powder X-ray diffraction. However, for sample number # 23, peaks of Ba ₄ Ti ₁₃ O ₃₀ and TiO ₂ were clearly recognized as impurity phases, and had an intensity of 5% or more of the main peak of BaTiO ₃ . In addition, the major axis / minor axis ratio of the powder was hardly changed by the acid treatment, and all were 2 or more. In addition, fine pores were observed in the acid-treated powder.

Next, the BaTiO ₃ powders of the sample numbers 21 and 22 were weighed 10% by weight as template powders. Further, spherical BaTiO ₃ powder having the same average particle diameter of 0.3 μm as that used in Example 1 was prepared, and 90 wt% was weighed as a matrix powder. The matrix powder and the template powder were dry-mixed to obtain ceramic powder (sample numbers 31 and 32, respectively), and then charged into the prepared resin container. Thereafter, the same evaluation as in Example 1 was performed.

  The results are shown in (Table 4) (results of # 11 are also shown). When the A / B ratio of the template powder was reduced, the {111} orientation degree of the sintered body was also increased, and the same tendency as in Example 1 was observed. Moreover, all the sintered compact density maintained 5.75-5.85, and the dense sintered compact was obtained.

  The present invention has a feature that a ceramic powder suitable for high dielectric constant and high reliability can be obtained, and particularly for ceramic electronic components that require high performance, downsizing, and high reliability. Useful.

Step diagram showing a method of manufacturing a ceramic electronic component according to an embodiment of the present invention Step diagram showing a method of manufacturing a ceramic electronic component according to another embodiment of the present invention Schematic diagram of the crystal structure of perovskite compounds Sectional drawing of the multilayer ceramic capacitor in one embodiment of this invention (A) Schematic sectional view of a laminate using the ceramic powder of the present invention, (b) Schematic sectional view of a sintered body obtained by firing the laminate. (A) Cross-sectional view of a laminate using conventional ceramic powder, (b) Schematic cross-sectional view of a sintered body obtained by firing the laminate X-ray diffraction spectrum diagram of BaTiO ₃ powder of sample number 3 X-ray diffraction spectrum of the surface of the alignment film of the same BaTiO ₃ powder Electron micrograph of the same BaTiO ₃ powder X-ray diffraction spectrum diagram of BaTiO ₃ powder of sample number 6 X-ray diffraction spectrum diagram of BaTiO ₃ sintered body surface of sample number 11 X-ray diffraction spectrum diagram of BaTiO ₃ sintered body surface of sample number 12 X-ray diffraction spectrum diagram of BaTiO ₃ sintered body surface of sample number 13 X-ray diffraction spectrum diagram of BaTiO ₃ sintered body surface of sample number 14

Explanation of symbols

300 Perovskite Compound 301 A Site Element 302 B Site Element 303 Oxygen Element 401 Dielectric Layer 402 Internal Electrode Layer 403 External Electrode 500 Third Ceramic Powder 501 First Ceramic Powder 502 Second Ceramic Powder 503 Ceramic Particles

Claims (15)

It consists essentially of a perovskite compound powder having shape anisotropy, and the general formula of this perovskite compound powder is ABO ₃ (A is an element at the A site, B is an element at the B site, and O is an oxygen element) and A ceramic powder having a molar ratio A / B of the element A to the element B of less than 1.00. The ceramic powder according to claim 1, wherein the element B contains Ti as a main component. The ceramic powder according to claim 2, wherein the element A contains at least one of Ca, Sr, and Ba as a main component. 4. The ceramic powder according to claim ₃ , wherein the element A contains Ba as a main component and the perovskite compound powder contains BaTiO ₃ as a main component. The ceramic powder according to claim 4, wherein the molar ratio A / B is 0.80 to 0.99. The ceramic powder according to claim 1, wherein a relationship between a major axis and a minor axis of the perovskite compound powder is major axis / minor axis ≧ 2. The ceramic powder according to claim 6, wherein the perovskite compound powder has a needle shape. The ceramic powder according to claim 6, wherein the perovskite compound powder has a plate shape. The ceramic powder according to claim 8, wherein a development surface of the perovskite compound powder has a {111} plane orientation preferentially. The ceramic powder according to claim 8, wherein the development surface of the perovskite compound powder has a {110} plane orientation preferentially. The ceramic powder according to claim 8, wherein the development surface of the perovskite compound powder has a {100} plane orientation preferentially. The ceramic powder according to claim 1, wherein the perovskite compound powder has crystal anisotropy. When the ceramic powder according to any one of claims 1 to 12 is used as a first ceramic powder, a second ceramic powder comprising the first ceramic powder and a non-formally anisotropic perovskite compound powder as a main component. Ceramic powder consisting of ceramic powder. In the second ceramic powder, when the general formula of the non-formally anisotropic perovskite compound powder is ABO ₃ (A is an element at the A site, B is an element at the B site, and O is an oxygen element) The ceramic powder according to claim 13, wherein the molar ratio A / B of the element A to the element B is greater than 1.00. A step of mixing the ceramic powder according to claim 1 with a dispersion medium to form a slurry, a step of forming the produced slurry into a sheet, and a step of laminating and firing the formed sheets A method for manufacturing a ceramic electronic component comprising: