JP2008074630A - Method for producing perovskite compound powder and ceramic electronic component using the perovskite compound powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a perovskite compound powder by which permittivity is improved. <P>SOLUTION: When the general formula of a perovskite compound is represented by ABO<SB>3</SB>(wherein A and B each represent an element, and O represents oxygen), the method comprises mixing a compound α which comprises at least element A and element B, the number of moles of element A being larger than the number of moles of element B, and a compound β which comprises at least element B, followed by heat-treating the resulting mixture. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a perovskite compound powder and a ceramic electronic component using the perovskite compound powder.

  Regarding a conventional method for producing a perovskite compound powder, a production method when barium titanate is used as the perovskite compound powder will be described.

  First, barium carbonate and titanium oxide are prepared, and mixed powder is prepared by mixing these barium carbonate and titanium oxide. Next, this mixed powder is calcined to produce barium titanate.

  The barium titanate thus prepared is added to a solvent together with a binder, a plasticizer and the like to form a slurry, which is applied onto a base film to produce a green sheet. This green sheet is alternately formed with, for example, an electrode layer. A multilayer ceramic electronic component is manufactured by laminating and firing.

  Along with the trend toward higher performance of electronic components in recent years, higher performance is also demanded for multilayer ceramic electronic components, and various studies have been conducted from the viewpoint of materials to meet this demand.

Patent Document 1 is known as prior art document information related to the present invention.
Japanese Patent No. 3780851

  When barium titanate is produced by the above-described conventional method, barium carbonate, which is an impurity, remains in the barium titanate, and this barium carbonate has various characteristics as barium titanate, such as dielectric constant. It will have an adverse effect.

  As a method of reducing the residual amount of barium carbonate, which is an impurity, it is conceivable to raise the calcining temperature, but by increasing the calcining temperature, interparticle sintering of barium titanate occurs in some places, resulting in large particles. As a result, it becomes barium titanate with irregular particle diameters. Therefore, even if a pulverization process is performed to reduce the size of the barium titanate particles that have been increased by raising the calcination temperature, the crystallinity of the particles is lowered, and as a result, the dielectric constant is lowered.

  Then, an object of this invention is to provide the manufacturing method of the perovskite compound powder which improves a dielectric constant.

In order to achieve this object, the present invention provides a perovskite compound having a general formula of ABO ₃ (A and B are elements, and O is oxygen, respectively). The compound α having a larger number of moles than the number of moles of the element B and the compound β containing at least the element B are mixed and heat-treated.

  According to the method for producing a perovskite compound powder of the present invention, a residual amount of impurities can be reduced and a perovskite compound powder with small particles can be obtained. As a result, the dielectric constant of a dielectric layer using the same can be obtained. Can be improved.

  Moreover, since the perovskite compound powder with small particles can be obtained, the dielectric layer using this can be thinned.

  Further, since nonuniformity of the particle diameter can be reduced, electric field concentration in the dielectric layer using the particle diameter can be suppressed, and as a result, reliability can be improved.

  Hereinafter, a method for producing a perovskite compound powder and a ceramic electronic component using the perovskite compound powder according to the present invention will be described with reference to an embodiment and drawings.

Incidentally, it is described with reference to barium titanate (BaTiO ₃₎ as a perovskite compound (ABO _3). Here, the element A is Ba and the element B is Ti.

FIG. 1 is a step diagram showing a method for producing barium titanate (BaTiO ₃ ) powder and ceramics using the same, and FIG. 2 is a conceptual diagram in the production process.

First, in order to produce dibarium titanate (Ba ₂ TiO ₄ ) as a compound α composed of at least element A and element B, and the number of moles of element A being larger than the number of moles of element B, barium carbonate (BaCO ₃ ) Titanium oxide (TiO ₂ ) is mixed and calcined (FIG. 1A). At this time, by setting the calcining temperature high, for example, about 1000 ° C., impurities remaining in dibarium titanate, that is, the remaining amount of barium carbonate can be reduced. Even if particle growth due to inter-particle sintering occurs by raising the calcination temperature, it is possible to reduce the dibarium titanate particles by pulverization in the immediately subsequent step. This pulverization is performed on the dibarium titanate particles, and the pulverization here does not adversely affect the crystallinity of the finally obtained barium titanate.

  Next, as shown in FIG. 2 (a), the prepared compound α, dibarium titanate 1, and titanium oxide 2 as a compound β containing at least element B are mixed and calcined, and FIG. 2 (b). To obtain barium titanate 3 (FIG. 1B). The calcining temperature at this time can be set lower than the calcining temperature for producing the above-mentioned dibarium titanate. Therefore, particle growth due to interparticle sintering can be suppressed, and as a result, barium titanate having small particles can be obtained.

  Next, the obtained barium titanate 3, binder, plasticizer and the like are dispersed in a solvent to prepare a slurry, which is applied onto a base film, and as shown in FIG. (FIG. 1C).

  For example, a laminate in which the green sheets 4 are alternately laminated with electrode layers is produced, and the binder 5 is fired to produce the ceramic 5 (FIG. 1D).

  As shown in FIG. 2D, the produced ceramic has a uniform and small particle size and a high dielectric constant.

  The titanium oxide 2 described above may have a so-called anisotropic shape having a shape such as a needle shape, a plate shape, or a column shape. Hereinafter, a description will be given with reference to FIG. FIG. 3 is a conceptual diagram in the production process of barium titanate powder and ceramics using the same.

  Titanium containing anisotropic shape barium titanate 7 shown in FIG. 3B by mixing and calcining the anisotropic shape titanium oxide 6 and dibarium titanate 1 shown in FIG. Barium acid 3 can be produced. The barium titanate 3 containing the barium titanate 7 containing the anisotropic shape thus obtained is slurried to produce the green sheet 8 shown in FIG. At this time, the short axis direction of the barium titanates 3 and 7 can be aligned with the thickness direction of the green sheet 8 by forming the slurry at the time of production of the green sheet 8 by applying shear stress. Thereby, the reliability of the thickness direction as ceramics can be improved.

  By firing the green sheet 8, as shown in FIG. 3D, a ceramic 9 having orientation can be obtained.

  In the case where dibarium titanate having an anisotropic shape is also used, the same effect as described above can be obtained.

  Further, by using both titanium oxide and dibarium titanate having an anisotropic shape, the reliability in the thickness direction as ceramics can be further improved. Hereinafter, a description will be given with reference to FIG. FIG. 4 is a conceptual diagram in the production process of barium titanate powder and ceramics using the same.

  The anisotropic shape barium titanate 11 shown in FIG. 4B is produced by mixing and calcining the titanium oxide 6 and dibarium titanate 10 having the anisotropic shape shown in FIG. 4A. be able to. The anisotropically-shaped barium titanate 11 thus obtained is slurried to produce a green sheet 12 shown in FIG. At this time, the minor axis direction of the barium titanate 11 can be aligned with the thickness direction of the green sheet 12 by forming the slurry at the time of producing the green sheet 12 by applying shear stress. Thereby, the reliability of the thickness direction as ceramics can be improved.

  By firing the green sheet 12, as shown in FIG. 4D, a ceramic 13 having high orientation can be obtained.

  When a ceramic electronic component, for example, a multilayer ceramic capacitor, is manufactured using the perovskite compound manufactured by the method for manufacturing a perovskite compound of the present invention described above, the electrode layers are alternately formed after the green sheet shown in FIG. 1C is manufactured. It is possible to produce a laminated body by laminating, and to produce the laminated body through steps of binder removal, calcination, and firing. At this time, a conventionally used material such as nickel, silver, palladium, or the like can be used for the electrode layer.

  By using the perovskite compound produced by the method for producing a perovskite compound of the present invention, the dielectric constant of the ceramic electronic component can be improved and the thinning of the dielectric layer can be realized.

  Moreover, since the nonuniformity of the particle diameter of a perovskite compound can be reduced, the reliability as a ceramic electronic component can also be improved.

  In addition, by using anisotropic titanium oxide or dibarium titanate, the reliability in the thickness direction of the ceramic can be improved, and the reliability of the ceramic electronic component can also be improved. When both titanium oxide and dibarium titanate have an anisotropic shape, the dielectric constant and reliability can be further improved as a ceramic electronic component.

  Ceramic electronic parts that can use the perovskite compound produced by the method for producing a perovskite compound of the present invention include, in addition to the ceramic capacitor described above, piezoelectric sensors represented by piezoelectric sensors, laminated actuators, piezoelectric oscillators, and piezoelectric filters. Examples thereof include a component, a multilayer inductor, a magnetic electronic component typified by a noise filter, a bandpass filter, an antenna switch module, a wireless run module, a high-frequency module typified by a Bluetooth module, an electronic component for a thermistor, or a composite component thereof.

  In the present embodiment, Ba is used as the element A, but Ca and Sr can also be used.

  The present invention is characterized in that a perovskite compound powder suitable for increasing the dielectric constant can be obtained, and is particularly useful for ceramic electronic parts and the like that require high performance, downsizing, and high reliability.

The step figure which showed the manufacturing method of the barium titanate powder and ceramics using the same in one embodiment of the present invention Conceptual diagram in the same manufacturing process Conceptual diagram Conceptual diagram

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dibarium titanate 2 Titanium oxide 3 Barium titanate 4 Green sheet 5 Ceramics 6 Titanium oxide 7 Barium titanate 8 Green sheet 9 Ceramics 10 Dibarium titanate 11 Barium titanate 12 Green sheet 13 Ceramics

Claims (8)

When the general formula of the perovskite compound is ABO ₃ (A and B are elements and O is oxygen, respectively), the compound is composed of at least element A and element B, and the number of moles of element A is larger than the number of moles of element B A method for producing a perovskite compound powder, wherein α and a compound β containing at least element B are mixed and heat-treated. The process for producing a perovskite compound powder according to claim 1, wherein the element A is selected from Ca, Sr, and Ba. The method for producing a perovskite compound powder according to claim ₂ , wherein the element B is Ti and the compound β is TiO ₂ . The method for producing a perovskite compound powder according to claim 3, wherein the element A is Ba. The method for producing a perovskite compound powder according to claim ₄ , wherein the compound α is Ba ₂ TiO ₄ . The method for producing a perovskite compound powder according to claim 5, wherein Ba ₂ TiO ₄ has an anisotropic shape. The method for producing a perovskite compound powder according to claim 3, wherein TiO ₂ has an anisotropic shape. The ceramic electronic component which used the perovskite compound powder produced with the manufacturing method of the perovskite compound powder as described in any one of Claims 1-7 for the dielectric material layer.

Images