JP2018090458A - Dielectric ceramic composition and manufacturing method therefor, and ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric ceramic composition which has high dielectric constant while having available temperature characteristics of capacitance in a range of -55°C or more and 200°C or less.SOLUTION: This invention relates to a dielectric ceramic composition comprising, as a main component, a complex oxide expressed by the composition formula (1): xBaTiO(1-x)BaTiO(provided that x in the composition formula (1) is more than 0.50 and less than 0.80), and comprising more than 0.1 mol% and less than 1.5 mol% of VO based on 100 mol% of the complex oxide.SELECTED DRAWING: None

Description

  The present invention relates to a dielectric ceramic composition, a method for producing the same, and a ceramic electronic component.

  With the spread of smartphones and tablets, electronic components used in these devices are required to be smaller and higher in performance. Of course, multilayer ceramic capacitors (MLCC) used as multilayer capacitors are also small in size. Large capacity is required.

  In particular, in recent years, as a characteristic required for in-vehicle MLCC, the temperature characteristic of capacitance is the X8R characteristic of EIA (American Electronic Industry Association) standard (within ΔC = ± 15% from −55 ° C. to 150 ° C .; There are demands for those satisfying the “X8R characteristics”) and having a high withstand voltage of 50 V or higher. As a dielectric ceramic composition satisfying such X8R characteristics, for example, Patent Document 1 discloses a dielectric ceramic composition containing barium titanate as a main component and at least three specific rare earth elements. ing.

  As a trend of the automobile industry, there is an increasing need for electrification of automobiles such as hybrid vehicles, electric vehicles (EV), and fuel cell vehicles (FCV). In recent years, the rise of smart car technology that enables automatic driving is expected to further increase demand for in-vehicle electronic components. In particular, various engine control-related boards called ECUs (Engine Control Units) are central parts for controlling engine operation, and a large number of MLCCs are mounted thereon. Furthermore, the number of MLCCs installed is also on a rapid increase with the increase in electrical equipment and performance of automobiles. In recent years, from the viewpoint of securing a living space for automobiles, it has been studied to install these ECU boards in an engine room where the temperature is extremely high, and the malfunction or breakage of the MLCC in a high temperature environment is suppressed. Therefore, high reliability is required for MLCC.

However, BaTiO ₃ (barium titanate) conventionally used for MLCC has a low Curie temperature of about 120 ° C., and is very difficult to use as a high-temperature dielectric material that can be used even at 200 ° C. or higher. Therefore, there is an urgent need to develop a high temperature dielectric that operates normally even under a high temperature environment of 200 ° C., that is, has a small rate of change in capacitance temperature.

JP 2013-227196 A

  As described above, with an increase in the use environment of in-vehicle electrical components, MLCCs that exhibit good capacity-temperature characteristics even at a high temperature of 200 ° C. are required. In other words, a dielectric ceramic composition that can be used even in a severer environment than the X8R characteristic will be required more and more in the future. Furthermore, the dielectric ceramic composition used for MLCC is required to have not only good capacity-temperature characteristics but also a high relative dielectric constant for the purpose of increasing the capacity.

  Accordingly, an object of the present invention is to provide a dielectric ceramic composition having a capacity-temperature characteristic that can be used in a range of −55 ° C. or higher and 200 ° C. or lower and having a high relative dielectric constant.

  The present inventors have intensively studied to solve the above problems. As a result, it has been found that a dielectric ceramic composition containing a barium titanate-based composite oxide having a specific composition as a main component and containing a specific amount of VO with respect to 100 mol% of the composite oxide solves the above problems. The present invention has been completed.

That is, the present invention has a composition formula (1): xBaTiO _3. (1-x) BaTi ₂ O ₅ (wherein x in the composition formula (1) is more than 0.50 and less than 0.80). It is a dielectric ceramic composition containing the composite oxide represented as a main component, and containing 0.1 mol% and less than 1.5 mol% of VO with respect to 100 mol% of the composite oxide.

  ADVANTAGE OF THE INVENTION According to this invention, while having the capacity | capacitance temperature characteristic which can be used in the range of -55 degreeC or more and 200 degrees C or less, the dielectric material ceramic composition which has a high dielectric constant is provided.

It is the graph which plotted the capacity | capacitance temperature change rate in each temperature of the dielectric ceramic composition which concerns on Example 1 and 2 and Comparative Example 1 and 2. FIG. It is the graph which plotted the capacity | capacitance temperature change rate in each temperature of the dielectric material ceramic composition which concerns on Example 3 and Comparative Examples 10 and 11. FIG.

  Embodiments of the present invention will be described below.

The first form of the present invention is the composition formula (1): xBaTiO ₃ · (1-x) BaTi ₂ O ₅ (wherein x in the composition formula (1) is more than 0.50 and less than 0.80) A dielectric ceramic composition (in the present specification), containing as a main component a composite oxide represented by the formula (1) and containing VO in an amount of more than 0.1 mol% and less than 1.5 mol% with respect to 100 mol% of the composite oxide And may be simply referred to as “composition”).

  In the present specification, the main component refers to the one having the largest number of moles in the compound constituting the dielectric ceramic composition.

  As described above, in recent years, not only does the temperature characteristic of capacitance satisfy the X8R characteristic, but it also has a capacity-temperature characteristic that can be used even in a harsher environment (especially at a high temperature of 200 ° C.). MLCCs are sought after. In order to manufacture such MLCC, a dielectric temperature coefficient (ΔC) is within ± 22% within the range of −55 ° C. or more and 200 ° C. or less (hereinafter, also simply referred to as “X9S characteristic”). There is a need for porcelain compositions.

As described above, various high-temperature dielectric materials have been studied in order to satisfy the capacity-temperature characteristics that can withstand use at higher temperatures than in the past. Against this background, the present inventors have earnestly obtained a dielectric ceramic composition that can achieve not only good capacitance-temperature characteristics but also high dielectric constant (specifically, ε ≧ 400). Study was carried out. As a result, a composite oxide containing barium titanate represented by composition formula: BaTiO ₃ and barium dititanate represented by composition formula: BaTi ₂ O ₅ at a specific ratio, and VO at a specific ratio. It has been found that the above-mentioned problems can be solved by a dielectric ceramic composition containing the dielectric ceramic composition.

  The reason why the above effect can be achieved is unknown, but is estimated as follows. In addition, this invention is not limited by the following estimation.

  The dielectric ceramic composition according to the present invention includes a barium titanate-based composite oxide represented by the above composition formula (1) (in the present specification, simply “barium titanate-based composite oxide” or “composite oxide”). May also be referred to).

Barium dititanate contained in the composite oxide according to the present invention has a monoclinic structure at room temperature (a = 16.892８９, b = 3.930Å, c = 9.410Å, β = 103. 03Å), has spontaneous polarization in the b-axis direction. Further, according to the projection onto the ac plane, it has three types of oxygen octahedrons (TiO ₆ , Ti ₂ O ₆ , Ti ₃ O ₆ ), and one of these is deformed to be ferroelectric. Expresses sex. Moreover, since the said barium dititanate single crystal has a high Curie point (about 470 degreeC), the application to the capacitor in a high temperature environment is expectable. However, it can be said that barium dititanate is a material that is difficult to put into practical use because of its low relative dielectric constant (ε) at room temperature.

On the other hand, barium titanate represented by the composition formula: BaTiO ₃ is a ferroelectric material having a relatively large relative dielectric constant (ε). The composition according to the present invention, as represented by the composition formula (1), contains barium titanate and barium dititanate in a specific content ratio (x: (1-x); By using a barium titanate-based composite oxide (composite oxide) containing more than 50 and less than 0.80, the advantages of both barium titanate and barium dititanate can be utilized. That is, in the composition formula (1), by setting x within the range of more than 0.50 and less than 0.80, the composition according to the present invention has both improved capacitance-temperature characteristics and relative dielectric constant. it is conceivable that.

  In the composition formula (1), when x is 0.50 or less, it is difficult to obtain a high relative dielectric constant (ε ≧ 400) because the content ratio of barium titanate is small. Moreover, when x is 0.80 or more, the influence of barium titanate having a low Curie point is increased, and excellent capacity-temperature characteristics in a high temperature environment derived from barium dititanate are not exhibited. Therefore, a desired capacity-temperature characteristic cannot be achieved.

  Furthermore, the composition according to the present invention contains VO at a specific ratio with respect to the barium titanate-based composite oxide represented by the composition formula (1). Specifically, the dielectric ceramic composition according to the present invention contains VO of more than 0.1 mol% and less than 1.5 mol% with respect to 100 mol% of the composite oxide. Here, VO is considered to contribute to the improvement of the capacity-temperature characteristic. More specifically, a part of VO can be dissolved in barium titanate contained in the composite oxide, so that the composite oxide can be stabilized by substituting the Ti site. It is estimated that the capacity-temperature characteristics are improved. Furthermore, since the stabilization of the crystal structure is promoted by partly dissolving VO in barium dititanate contained together in the composite oxide, the composition of the present invention has a particularly excellent capacity temperature. Presumed to have characteristics.

  When the content ratio of the VO is 0.1 mol% or less with respect to 100 mol% of the composite oxide, the change of the crystal phase due to the solid solution of VO as described above is not sufficient, and the effect of improving the capacity-temperature characteristic is achieved. The desired capacity-temperature characteristic (X9S characteristic) cannot be obtained. Further, when the content is 1.5 mol% or more with respect to 100 mol% of the composite oxide, VO is not sufficiently dissolved, an impurity phase is generated, and as a result, a desired capacity-temperature characteristic cannot be obtained, and dielectric The rate is also greatly reduced.

  As a result of the study by the present inventors, it has been found that VO has low reactivity with the barium titanate-based composite oxide and is excellent in sinterability. Therefore, the composition according to the present invention can easily obtain a high relative dielectric constant due to barium titanate.

  As described above, the composition according to the present invention satisfies the X9S characteristics by including the composite oxide containing barium titanate and barium dititanate in the specific ratio and VO in the specific ratio, and It is considered that a high relative dielectric constant can be achieved.

Furthermore, the composition according to the present invention does not use expensive niobium (Nb) as compared with KNbO ₃ , K _0.5 Na _0.5 NbO ₃ , NaNbO _3, etc., which are also known as high-temperature dielectric materials. Therefore, it is advantageous in terms of cost. Moreover, it can be said that it is superior to the said Nb type dielectric material also at the point which can use a cheap Ni-type electrode as an internal electrode and an external electrode material.

  Hereinafter, the dielectric ceramic composition of the present invention will be described in detail. Unless otherwise specified, measurements such as operation and physical properties are performed under conditions of room temperature (25 ° C.) / Relative humidity of 40% RH or more and 50% RH or less.

<Dielectric porcelain composition>
The dielectric ceramic composition of the present invention is a ceramic mainly composed of a barium titanate-based composite oxide represented by the composition formula (1). The definition of the term “consisting of the main component” is as described above, and a small amount of impure components that are included in the production may be included in the dielectric ceramic composition. Examples of impure components include metal-derived components such as sodium, calcium, niobium, iron, lead, hydrocarbon-based organic components, surface adsorbed water, and the like.

≪Main ingredient≫
The dielectric ceramic composition of the present invention contains, as a main component, a barium titanate-based composite oxide represented by a composition formula (1): xBaTiO _3. (1-x) BaTi ₂ O ₅ . Barium titanate has a high dielectric constant, and barium dititanate has good capacity-temperature characteristics.

In the composition formula (1), “x” indicating the content ratio of barium titanate (BaTiO ₃ ) is more than 0.50 and less than 0.80. For the purpose of obtaining a dielectric ceramic composition having good capacity-temperature characteristics at −55 ° C. or more and 200 ° C. or less and having a high relative dielectric constant, the above “x” is more than 0.55 and less than 0.75. Preferably, it is 0.60 or more and 0.70 or less, more preferably 0.60 or more and 0.65 or less. On the other hand, “1-x” indicating the content ratio of barium dititanate (BaTi ₂ O ₅ ) is more than 0.20 and less than 0.50. For the purpose of obtaining a dielectric ceramic composition having good capacity-temperature characteristics in the range of −55 ° C. or more and 200 ° C. or less and having a high relative dielectric constant, the above “1-x” exceeds 0. Is preferably less than 0.45, more preferably 0.30 or more and 0.40 or less, and particularly preferably 0.30 or more and 0.35 or less. The values of “x” and “1-x” can be obtained by XRD measurement, and more specifically, values obtained by the method (measurement conditions) described in the examples are adopted. The values of “x” and “1-x” can be controlled by the amount of barium titanate and barium dititanate added when the dielectric ceramic composition is manufactured.

≪Sub ingredients≫
The dielectric ceramic composition of the present invention includes a vanadium component (VO) as a subcomponent. Moreover, the dielectric ceramic composition of the present invention may further contain a silicon component (SiO), a barium component (BaO), a manganese component (MnO), and other components as necessary.

(Vanadium component: VO)
The dielectric ceramic composition according to the present invention contains VO, and the content thereof is more than 0.1 mol% and less than 1.5 mol% with respect to 100 mol% of the barium titanate-based composite oxide. VO is a component added for the purpose of improving the reliability of the dielectric ceramic composition in addition to the role as a sintering aid. When VO is contained more than 0.1 mol% and less than 1.5 mol% with respect to 100 mol% of the barium titanate-based composite oxide, it has excellent capacity-temperature characteristics and relative dielectric constant, and is suitable for ceramic electronic components such as capacitors. A dielectric ceramic composition having excellent applicability can be obtained.

The barium titanate contained in the barium titanate-based composite oxide according to the present invention has a characteristic that it decomposes at 1150 ° C. or more and decomposes into BaTiO ₃ and Ba ₆ Ti ₁₇ O _{40, and is} put into practical use. From this point of view, there are various technical problems. However, the dielectric ceramic composition according to the present invention includes a barium titanate-based composite oxide composed of barium titanate and barium dititanate, and also contains the above-mentioned specific amount of VO. The stability of the crystal structure is improved. For this reason, when producing the dielectric ceramic composition according to the present invention, firing is possible even at a high temperature of about 1250 ° C. or less.

  When the content ratio of VO is 0.1 mol% or less, it is not possible to suppress the destabilization of the crystal structure due to the increase of oxygen defects in barium dititanate that occurs during reduction firing, so that the capacity temperature characteristics can be sufficiently improved. I can't. On the other hand, when the content ratio of VO is 1.5 mol% or more, the effect of improving the capacity-temperature characteristic cannot be obtained due to the generation of the impurity phase, and the X9S characteristic cannot be satisfied.

Furthermore, from the viewpoint of obtaining a dielectric ceramic composition having good capacity-temperature characteristics and a high relative dielectric constant while maintaining good sinterability, the content of VO is the above-mentioned barium titanate-based composite oxide. More preferably, it is more than 0.1 mol% and less than 1.3 mol%, more preferably 0.2 mol% or more and 1.2 mol% or less, and 0.25 mol% or more and 1.0 mol% or less with respect to 100 mol%. Is even more preferable, and is particularly preferably 0.25 mol% or more and 0.8 mol% or less. The content of VO in the dielectric ceramic composition is the same as that of a vanadium compound (for example, V ₂ O ₅ , NH ₄ VO ₃ , VOCl _3, etc.) added when the dielectric ceramic composition is manufactured. Controllable by quantity.

(Silicon component: SiO)
The dielectric ceramic composition according to the present invention may contain other subcomponents other than VO.

  Examples of other subcomponents include SiO. SiO is a component added mainly as a sintering aid. The content of SiO is not particularly limited, but is preferably 0.1 mol% or more and 5.0 mol% or less with respect to 100 mol% of the barium titanate composite oxide. When SiO is contained in an amount of 0.1 mol% or more with respect to 100 mol% of the barium titanate-based composite oxide, a capacitor or the like can be obtained without impairing the excellent capacity-temperature characteristics and insulation resistance of the barium titanate-based composite oxide. A dielectric ceramic composition excellent in applicability to ceramic electronic components can be obtained. On the other hand, when the content of SiO is 5.0 mol% or less, the relative dielectric constant becomes good.

Furthermore, from the viewpoint of obtaining a dielectric ceramic composition having a good dielectric constant while maintaining good sinterability, the content of SiO is based on 100 mol% of the barium titanate-based composite oxide. More preferably, it is more than 0.3 mol% and less than 3.0 mol%, more preferably 0.5 mol% or more and 2.5 mol% or less, and further more preferably 0.5 mol% or more and 2.0 mol% or less. Preferably, it is more preferably 0.8 mol% and less than 1.5 mol%. The content of SiO in the dielectric ceramic composition can be controlled by the amount of silicon compound (for example, SiO ₂ ) added when the dielectric ceramic composition is manufactured.

(Barium component: BaO)
The dielectric ceramic composition according to the present invention may contain BaO as a subcomponent other than VO. BaO is a component added mainly as a sintering aid. The content of BaO is not particularly limited, but is preferably 0.1 mol% or more and 2.0 mol% or less with respect to 100 mol% of the barium titanate-based composite oxide. When BaO is contained in an amount of 0.1 mol% or more with respect to 100 mol% of the barium titanate composite oxide, the sinterability is improved and the relative dielectric constant is also improved. On the other hand, when the content of BaO is 2.0 mol% or less, semiconductorization is suppressed and good insulating properties are obtained.

Furthermore, from the viewpoint of obtaining a composition having an excellent relative dielectric constant and insulation while maintaining good sinterability, the content of BaO is based on 100 mol% of the barium titanate-based composite oxide. More preferably more than 0.15 mol% and less than 1.8 mol%, still more preferably 0.2 mol% or more and 1.5 mol% or less, and more than 0.5 mol% and less than 1.3 mol% Particularly preferred. The content of BaO in the dielectric ceramic composition can be controlled by the amount of a barium compound (for example, BaO, BaCO _3, etc.) added when the dielectric ceramic composition is manufactured.

(Manganese component: MnO)
The dielectric ceramic composition according to the present invention may contain MnO as a subcomponent other than VO. MnO is a component added mainly as a reduction resistance aid. The MnO content is not particularly limited, but is preferably 0.1 mol% or more and 1.0 mol% or less with respect to 100 mol% of the barium titanate-based composite oxide. When MnO is contained in an amount of 0.1 mol% or more with respect to 100 mol% of the barium titanate-based composite oxide, oxygen vacancies generated in the firing step in a reducing atmosphere can be effectively suppressed. As a result, when a ceramic electronic component such as a capacitor is manufactured using the dielectric ceramic composition, the reliability of the ceramic electronic component is improved. On the other hand, when the content of MnO is 1.0 mol% or less, the relative dielectric constant becomes good.

Furthermore, from the viewpoint of obtaining a dielectric ceramic composition having a good dielectric constant, the content of MnO exceeds 0.1 mol% with respect to 100 mol% of the barium titanate-based composite oxide, and 1. It is more preferably less than 0 mol%, even more preferably 0.15 mol% or more and 0.8 mol% or less, and particularly preferably more than 0.15 mol% and less than 0.8 mol%. Note that the content of MnO in the dielectric ceramic composition is that of a manganese compound (for example, MnO ₂ , Mn ₂ O ₃ , Mn ₃ O _4, etc.) added when the dielectric ceramic composition is manufactured. Controllable by quantity.

(Other minor ingredients)
The dielectric ceramic composition according to the present invention may contain subcomponents other than the above as long as the effects of the present invention are obtained. Examples of such subcomponents include magnesium compounds, calcium compounds, rare earth element compounds, aluminum compounds, and the like. More specific compounds include, for example, magnesium compounds such as magnesium oxide (MgO); calcium compounds such as calcium carbonate (CaCO ₃ ); dysprosium oxide (Dy ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), and ytterbium oxide. Examples thereof include compounds of rare earth elements such as (Yb ₂ O ₃ ) and aluminum compounds such as aluminum oxide (Al ₂ O ₃ ). Moreover, components other than the above, such as sintering aids and reduction resistance aids, may be further included.

≪Form and characteristics of dielectric ceramic composition≫
The form of the dielectric ceramic composition according to the present invention is not particularly limited. For example, it can take the form of a sphere, plate, pellet, or a mixture thereof.

  The dielectric ceramic composition according to the present invention is excellent in capacity-temperature characteristics, and exhibits a low capacity-temperature change rate in a range of −55 ° C. or more and 200 ° C. or less. The capacity temperature change rate (ΔC) is defined by the following equation.

  The capacity temperature change rate (ΔC) of the dielectric ceramic composition is preferably within ± 22% within a range of −55 ° C. or more and 200 ° C. or less. Further, the capacity temperature change rate (ΔC) is more preferably within ± 20%, and even more preferably within ± 15%. In the above formula, the capacitance at each temperature can be measured by the method described in the examples.

  Furthermore, it is preferable that the dielectric ceramic composition of the present invention exhibits a high relative dielectric constant. The relative dielectric constant is preferably 400 or more, more preferably 500 or more, and particularly preferably 600 or more. On the other hand, the upper limit is not particularly limited, but is substantially 5000 or less. The relative dielectric constant can be measured by the method described in the examples.

  The dielectric ceramic composition of the present invention having such characteristics can be obtained by the following production method. Hereinafter, a method for producing a dielectric ceramic composition will be described.

<Method for Producing Dielectric Porcelain Composition>
The dielectric ceramic composition according to the present invention is not particularly limited as long as it has the above composition, but preferred methods include (1) a step of obtaining a molded body and (2) a method of undergoing a firing step. . Hereinafter, each step will be described in detail.

(1) Step of obtaining a molded body In this step, (1-1) barium titanate, barium dititanate, a vanadium compound, and other subcomponents (raw materials of subcomponents) added as necessary , And a step of preparing a mixture (mixture preparation step) and (1-2) a step of obtaining a molded body by using the obtained mixture (green sheet manufacturing step).

(1-1) Mixture preparation step In this step, barium titanate (BaTiO ₃ ), barium dititanate (BaTi ₂ O ₅ ), a vanadium compound serving as a raw material for VO, and others added as necessary And a secondary component (raw material of the secondary component) are mixed to prepare a mixture (slurry) for forming a molded body (green sheet).

  At this time, the amount of barium titanate and barium dititanate is adjusted so that “x” in the composition formula (1) is within a predetermined range. That is, the molding is performed so that the molar ratio (x: 1-x) of barium titanate to barium dititanate is in the range of more than 0.50: less than 0.50 to less than 0.80: more than 0.20. A mixture (slurry) for preparing a body (green sheet) is prepared. The molar ratio of the barium titanate to barium dititanate is more preferably in the range of more than 0.55: less than 0.45 to less than 0.75: more than 0.25, and 0.60: 0. More preferably within the range of .40 to 0.70: 0.30, and particularly preferably within the range of 0.60: 0.40 to 0.65: 0.35. In the present specification, the description “from X to Y” refers to a range including the values of “X” and “Y”.

  As barium titanate and barium dititanate as raw materials, commercially available barium titanate powders may be used, and in addition to the solid phase method, various production methods (for example, oxalate method, hydrothermal synthesis method, alkoxide method) , A sol-gel method, etc.).

  The average particle diameter of barium titanate and barium dititanate used in this step is not particularly limited, but both are preferably 5000 nm or less, and more preferably 50 nm or more and 1000 nm or less. In addition, the value measured by the method of an Example is employ | adopted for the average particle diameter of each particle | grain.

  Further, in this step, the vanadium compound is added so that the addition amount (total) of these barium titanate and barium dititanate is 100 mol%, and VO is more than 0.1 mol% and less than 1.5 mol%. That is, the vanadium compound is added so that VO is more than 0.1 mol% and less than 1.5 mol% with respect to 100 mol% of the barium titanate-based composite oxide produced by barium titanate and barium dititanate. The preferred addition amount of the vanadium compound and the addition amount of the subcomponent (subcomponent raw material) added as necessary can be calculated from the content (or preferred content) of each of the above components. I won't go into detail.

The vanadium compound used in the method for producing the composition according to the present invention is not particularly limited. For example, V ₂ O ₅ , NH ₄ VO ₃ , VOCl ₃ , NaVO ₃ , KVO ₃ , Na ₃ VO ₄ , VCl ₄ , VOSO ₄ , VOCl ₂ , VO ₂ , VCl ₃ , V ₂ O ₃ , V ₆ O _{13 and the} like can be mentioned. Among these, vanadium oxide is preferably used as the vanadium compound from the viewpoint of easy availability and suppression of contamination of other components, and V ₂ O ₅ , VO ₂ , V ₂ O ₃ are particularly used. And more preferred. In addition, you may use these vanadium compounds individually or in combination of 2 or more types.

  Although the average particle diameter of the vanadium compound used in this step is not particularly limited, it is preferably 5000 nm or less and more preferably 50 nm or more and 500 nm or less. In addition, the value measured by the method of an Example is employ | adopted for the average particle diameter of each particle | grain.

  Furthermore, in this step, other subcomponents (subcomponent raw materials) described above and additives such as a binder, a plasticizer, and a dispersant may be mixed as necessary.

As other subcomponents (raw materials of subcomponents) used in the method for producing a composition according to the present invention, the compounds exemplified in the description of each component can be used as appropriate, and are not particularly limited thereto. From the viewpoint of easy availability, easy handling, and suppression of impurities, for example, silicon oxide (SiO ₂ etc.), barium oxide (BaO etc.), barium carbonate (BaCO ₃ ), manganese oxide (MnO ₂₎ , Mn ₂ O ₃ , Mn ₃ O ₄ or the like). In addition, also about the said vanadium compound and the accessory component (raw material of an accessory component) added as needed, a commercial item may be used and a synthetic product may be used.

  Next, a binder, a plasticizer, and a dispersant that can be included in a mixture (slurry) for forming a molded body (green sheet) will be described. The additives that can be contained in the mixture (slurry) are not limited to those listed below, and other additives such as lubricants and antistatic agents may be used as long as the effects of the present invention are not impaired. Good.

  Although it does not restrict | limit especially as a binder which can be contained in the mixture (slurry) for a molded object (green sheet) preparation, For example, polyvinyl alcohol (PVA), polyvinyl butyral (PVB), an acrylic resin etc. are mentioned. In addition, the said binder may be used individually or in combination of 2 or more types.

  The amount of the binder used is not particularly limited, but is 0.01% by mass or more and 20% by mass or less with respect to the total mass (total mass) of barium titanate, barium dititanate and subcomponents (raw materials of subcomponents). Preferably, it is 0.5 mass% or more and 15 mass% or less. By setting it as this range, the density of a molded object can be improved.

  In addition, the plasticizer that can be included in the mixture (slurry) for forming the molded body (green sheet) is not particularly limited, and examples thereof include dioctyl phthalate (DOP), benzylbutyl phthalate, dibutyl phthalate, and dihexyl phthalate. , Phthalic acid plasticizers such as di (2-ethylhexyl) phthalate (DEHP) and di (2-ethylbutyl) phthalate, adipic acid plastics such as dihexyl adipate and di (2-ethylhexyl) adipate (DOA) Agents, glycol plasticizers such as ethylene glycol, diethylene glycol, triethylene glycol, glycols such as triethylene glycol dibutyrate, triethylene glycol di (2-ethylbutyrate), triethylene glycol di (2-ethylhexanoate) Examples include ester plasticizers It is. Among these, phthalic acid such as dioctyl phthalate, dibutyl phthalate, di (2-ethylhexyl) phthalate, etc., when the mixture (slurry) is used as a green sheet, the sheet has good flexibility. It is preferable to use a plasticizer. In addition, the said plasticizer may be used individually or in combination of 2 or more types.

  The amount of the plasticizer used is not particularly limited, but is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 50% by mass or less, based on the total mass of the binder to be added. It is particularly preferable that the content is not less than 40% by mass and not more than 40% by mass. By setting it within the above range, a sufficient effect as a plasticizer can be obtained.

  Furthermore, the dispersant that can be contained in the mixture (slurry) for producing a molded body (green sheet) is not particularly limited, and examples thereof include a phosphate ester dispersant and a polycarboxylic acid dispersant. Among these, it is preferable to use a phosphate ester dispersant. In addition, you may use the said dispersing agent individually or in combination of 2 or more types.

  The amount of the dispersant used is not particularly limited, but is 0.1% by mass to 5% by mass with respect to the total mass (total mass) of the barium titanate, barium dititanate, and subcomponents (subcomponent raw materials). Or less, more preferably 0.3% by mass or more and 3% by mass or less, and further preferably 0.5% by mass or more and 1.5% by mass or less. By setting it within the above range, a sufficient effect as a dispersant can be obtained.

  The mixing method and mixing order of the above components are not particularly limited, but wet mixing is preferable as the mixing method in that the additive can be uniformly dispersed.

  The solvent used in the case of wet mixing is not particularly limited. For example, water; alcohol solvents such as ethanol, methanol, benzyl alcohol, and methoxyethanol; glycol solvents such as ethylene glycol and diethylene glycol; acetone, methyl ethyl ketone, and methyl isobutyl ketone. Ketone solvents such as cyclohexanone; ester solvents such as butyl acetate, ethyl acetate, carbitol acetate, and butyl carbitol acetate; ether solvents such as methyl cellosolve, ethyl cellosolve, butyl ether, and tetrahydrofuran; aromatic solvents such as benzene, toluene, and xylene Etc. Later, considering the solubility and dispersibility of various additives contained in the mixture (slurry), the solvent for the wet mixing is preferably an alcohol solvent or an aromatic solvent. Among these, it is preferable to use a low boiling point solvent such as methanol as the alcohol solvent and toluene as the aromatic solvent. In addition, the said solvent may be individual or may use 2 or more types together by arbitrary combinations and a ratio. When mixing two or more solvents, it is particularly preferable to mix the alcohol solvent and the aromatic solvent.

  The amount used in the case of using a solvent is preferably about 0.5 to 10 times the total mass (total mass) of barium titanate, barium titanate and subcomponents (subcomponent raw materials), More preferably, it is about 0.7 to 5 times. By setting the amount within the above range, barium titanate, barium dititanate, subcomponents (raw materials of subcomponents), and additives that are added as necessary are mixed sufficiently, and the solvent is removed later. Can be performed easily.

  Moreover, when performing wet mixing, it is preferable to carry out by a wet ball mill, a wet bead mill, or a stirring mill. When zirconia balls are used in a wet ball mill, wet mixing is preferably performed using a large number of zirconia balls having a diameter of 0.1 mm to 10 mm, preferably 8 hours to 48 hours, more preferably 10 hours to 24 hours.

(1-2) Green Sheet Production Step In this step, the mixture obtained in the step (1-1) is formed into a sheet having an appropriate size and shape to produce a molded body (green sheet). To do. Here, it does not specifically limit as a method of producing a green sheet, A conventionally well-known method can be used. For example, a green sheet is obtained by forming into a sheet by a tape forming method such as a doctor blade method or a calender roll method, and drying the sheet.

  The thickness of the green sheet (thickness after drying) is not particularly limited, but is preferably 30 μm or less, and more preferably 20 μm or less. On the other hand, the lower limit of the thickness of the green sheet (thickness after drying) is not particularly limited, but is substantially 0.5 μm or more.

  Further, the obtained green sheets may be laminated until a desired thickness is obtained, and then thermocompression bonding may be performed. At this time, lamination is preferably performed until the total thickness (thickness after drying) is preferably about 0.1 mm to 5 mm, more preferably about 1 mm to 3 mm. Further, the conditions at the time of thermocompression bonding are not particularly limited, but the temperature is preferably about 50 to 150 ° C., the pressure is preferably about 10 to 200 MPa, and the pressurization time is about 1 to 30 minutes. Is preferable. Examples of the thermocompression bonding method include a warm isostatic pressing method (WIP).

  Thereafter, a green chip may be produced by cutting a laminate of green sheets into a desired chip shape.

  Furthermore, it is preferable to perform a so-called degreasing process, in which a binder component or the like contained in the obtained green sheet (or green chip) is thermally decomposed and removed. The degreasing conditions are not particularly limited and depend on the type of binder used, but are preferably 180 ° C. or higher and 450 ° C. or lower. The degreasing time is not particularly limited, but is preferably 0.5 hours or more and 24 hours or less. Furthermore, the degreasing treatment can be performed in air or in an inert gas such as nitrogen or argon, but it is preferably performed in air from the viewpoint of ease of operation.

(2) Firing step In this step, the green sheet (or green chip) obtained in the step (1-2) is fired.

The firing temperature in this step is not particularly limited as long as the dielectric ceramic composition can be obtained, but is preferably 1250 ° C. or lower. That is, in the second embodiment of the present invention, barium titanate represented by BaTiO ₃ , barium dititanate represented by BaTi ₂ O ₅ , and a vanadium compound are mixed and molded, and a molded body is formed. A method for producing a dielectric ceramic composition, comprising: obtaining the molded body at a temperature of 1250 ° C. or less, wherein the barium titanate and the dititanium are obtained in the step of obtaining the molded body. The molar ratio with barium acid is in the range of 0.20: 0.80 to 0.50: 0.50, and the vanadium compound is added to 100 mol% in total of the barium titanate and the barium dititanate. In this method, the dielectric ceramic composition is added so as to be more than 0.1 mol% and less than 1.5 mol% in terms of VO.

  Thus, in the production process of the dielectric ceramic composition, it is preferable to set the firing temperature to a relatively low temperature of 1250 ° C. or lower. By sintering at such a low temperature, decomposition of barium dititanate and the formation of a solid solution of barium titanate and barium dititanate are suppressed.

  Furthermore, for the purpose of suppressing the decomposition of barium dititanate and the formation of a solid solution between barium titanate and barium dititanate, the firing temperature is more preferably 1200 ° C. or lower.

  As described above, barium dititanate is known to decompose at 1150 ° C. or higher. However, the present inventors set the firing temperature to 1150 ° C. in the production process of the dielectric ceramic composition according to the present invention. The present inventors have also found that barium dititanate does not decompose. Although the mechanism by which such an effect of suppressing the decomposition of barium dititanate is obtained is unknown, in the composition formula (1), in addition to setting the value of “x” within a predetermined range, the dielectric ceramic composition As a result of the inclusion of VO in a predetermined ratio, a part of the B-site atom of barium dititanate is substituted from Ti to V atom, so that the stabilization of the crystal structure proceeds and the decomposition is assumed to be suppressed. The Conventionally, it has been difficult to effectively utilize characteristics such as capacity-temperature characteristics of barium dititanate, but according to the present invention, since decomposition of barium dititanate is suppressed, It is possible to effectively utilize the excellent capacity-temperature characteristics of the.

  On the other hand, the lower limit of the firing temperature is not particularly limited as long as a sintered body can be obtained, but is preferably 1000 ° C. or higher and more preferably 1150 ° C. or higher.

  The firing time is not particularly limited, but is preferably 1 hour or longer and 5 hours or shorter, and more preferably 1 hour or longer and 3 hours or shorter. The firing atmosphere is not particularly limited, and examples thereof include an air atmosphere, an inert gas atmosphere such as nitrogen and argon, or a reducing atmosphere in which hydrogen, water vapor, or the like is mixed with nitrogen or argon.

  As other firing conditions, the heating rate is preferably 50 ° C./hour or more and 500 ° C./hour or less, more preferably 200 ° C./hour or more and 300 ° C./hour or less.

<Ceramic electronic parts>
A third aspect of the present invention is a ceramic electronic component including the dielectric ceramic composition or the dielectric ceramic composition obtained by the manufacturing method. The dielectric ceramic composition of the present invention or the dielectric ceramic composition obtained by the production method of the present invention can be suitably used for various ceramic electronic components. Hereinafter, a multilayer ceramic capacitor, which is an example of a ceramic electronic component, will be described.

(Multilayer ceramic capacitor)
A dielectric ceramic composition obtained by firing a green sheet (or green chip) has a thin film shape and can be used as a dielectric layer of a multilayer ceramic capacitor (MLCC). Although it does not restrict | limit especially as a manufacturing method of a multilayer ceramic capacitor, For example, it manufactures as follows.

  First, an internal electrode conductive paste containing various metals or the like is screen-printed in a predetermined shape on the green sheet to form an internal electrode conductive paste film. The material for the internal electrode is not particularly limited, and examples thereof include a metal such as Cu, Ni, W, Mo, Ag, Pt, and Pd, or an alloy thereof.

  The material of the external electrode is not particularly limited, and examples thereof include metals such as Cu, Ni, W, Mo, Ag, Pt, and Pd or alloys thereof; alloys such as In—Ga and Ag-10Pd; carbon, graphite, and carbon And those composed of a mixture of graphite and graphite.

  Then, after laminating a plurality of green sheets on which the internal electrode conductive paste film is formed, and laminating and crimping the green sheets on which the conductive paste film is not formed so as to sandwich the green sheets, A laminated body (green chip) is obtained by cutting as necessary.

  And after performing a binder removal process to the obtained laminated body (green chip), the said green chip is baked in inert gas atmosphere or reducing atmosphere, and a capacitor chip body is obtained. In the capacitor chip body, dielectric layers made of a sintered body obtained by firing green sheets and internal electrodes are alternately laminated. What is necessary is just to employ | adopt suitably the conditions shown by said (2) baking process as baking conditions.

  When firing is performed in a reducing atmosphere, it is preferable to anneal the obtained capacitor chip body in order to reoxidize the dielectric layer.

  Next, an external electrode paste containing the above various metals on the end face of the capacitor chip body so that the external electrode is electrically connected to each edge of the internal electrode exposed from the end face of the capacitor chip body. The external electrode is formed by coating. Then, if necessary, a coating layer is formed on the external electrode surface by plating or the like. In this way, a multilayer ceramic capacitor can be manufactured.

  Although the multilayer ceramic capacitor has been described as an example of the ceramic electronic component, the ceramic electronic component according to the present invention is not limited to this. For example, various other components such as a high-frequency module, an electronic component for the thermistor, or a composite component thereof may be used.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

<Preparation of dielectric ceramic composition>
The following materials were used.

The barium titanate and barium dititanate were prepared using titanium oxide (TiO ₂ Super Titania (registered trademark): F-2, Showa Denko KK) and barium carbonate (BaCO ₃ BW-KH30, Sakai Chemical Industry). Used). When producing barium titanate with respect to 1 mol of barium carbonate, 1 mol of titanium oxide was added, and when producing barium dititanate, 2 mol of titanium oxide was added and mixed well. Thereafter, barium titanate and barium dititanate were respectively obtained by heat treatment (calcination) at 900 ° C. for 3 hours.

  In the above, the “average particle size” is obtained by taking an image with a scanning electron microscope, extracting 50 particles at random, measuring the particle size, and averaging the results. Moreover, when the shape of particle | grains is not spherical, it defines as what was calculated by measuring a major axis.

<< Examples 1-6, Comparative Examples 1-9 >>
Each raw material of barium titanate (BaTiO ₃ ), barium dititanate (BaTi ₂ O ₅ ), SiO ₂ , BaCO ₃ , Mn ₃ O ₄ and V ₂ O ₅ so as to have the composition ratios shown in Table 1 and Table 2 below. Were weighed using an electronic balance. In Table 1 below, the ratio (mol%) of SiO, BaO, MnO and VO is a value when the total of barium titanate and barium dititanate is 100 mol%, respectively. _The amount of _{SiO 2, BaCO 3, Mn 3} O 4 and _V 2 _{O 5,} respectively, were weighed in such a manner that SiO in the following Table 1, BaO, and the ratio of MnO and VO. In addition, "-" in a table | surface shows not including an applicable component.

BYK-103 (manufactured by Big Chemie Japan), a mixed solvent of ethanol / toluene (60/40 mass ratio) and a phosphoric acid ester-based dispersant so that the solid content is 40% by mass in the raw material powder prepared in a predetermined composition Is added to 1 mass% with respect to the total mass (total mass) of barium titanate, barium dititanate, SiO ₂ , BaCO ₃ , Mn ₃ O ₄ and V ₂ O ₅ , and ₃ mmφ ZrO ₂ Wet mixing with a rotating ball mill was performed at 25 ° C. for 14 hours using balls. Thereafter, a binder (PVB, manufactured by Sekisui Chemical Co., Ltd., BH-3) solution (PVB solid content 15% by mass, solvent: ethanol / toluene = 60/40 mass ratio), PVB / total of each raw material = 10/90 It added so that it might become mass ratio. Furthermore, dioctyl phthalate (DOP) was added so that it might become 30 mass% with respect to binder (PVB), and it mixed at 25 degreeC for 4 hours using the rotating ball mill, and obtained the ceramic slurry.

Using the obtained ceramic slurry, a sheet was formed on a PET film by a doctor blade method using a 350 μm gap applicator. 50 layers of the obtained green sheets (thickness: about 20 μm) are laminated and heat press molding is performed (pressurization temperature: 80 ° C., pressurization pressure: 50 MPa, pressurization time: 3 minutes), cut into 1 cm square. The binder removal treatment was performed under the conditions of 400 ° C. × 2 hours. Thereafter, the temperature was raised at a rate of temperature increase of 200 ° C./hour, and the firing temperature was set to 1200 ° C. (oxygen partial pressure 2.0 × 10 ^{−10 to} 1.5 × 10 ⁻⁹ atm (2.0 × 10 ⁻⁵ to 1 .5 × 10 ⁻⁴ Pa) and firing time: 2 hours) to obtain a dielectric ceramic composition.

<< Comparative Example 10 >>
A dielectric ceramic composition was obtained in the same manner as in Example 1 except that the raw materials and the amounts used were changed so that the following composition ratio was obtained.

  (Composition of the dielectric ceramic composition of Comparative Example 10)

<< Comparative Example 11 >>
A dielectric ceramic composition was obtained in the same manner as in Example 1 except that the raw materials and the amounts used were changed so that the following composition ratio was obtained.

  (Composition of the dielectric ceramic composition of Comparative Example 11)

<< Comparative Example 12 >>
In Example 3, a dielectric ceramic composition was obtained in the same manner as in Example 3 except that barium dititanate was not added and the amount of barium titanate added was changed.

<Evaluation>
The dielectric ceramic compositions obtained in the above examples and comparative examples were evaluated as follows.

≪XRD measurement≫
Each dielectric ceramic composition was subjected to XRD measurement (measurement was performed using an X-ray diffractometer (manufactured by PANalytical, RAYONS X, the radiation source being Cu-Kα, voltage 45 kV, current 40 mA). As a result, it was confirmed that the content ratio of each component in the obtained dielectric ceramic composition was the same as the addition amount (ratio) of each component described in Table 1 and Table 2 (however, Comparative Example 11 was used). The values of “x” and “1-x” in the obtained dielectric ceramic composition are values obtained from the XRD measurement results, and BaTiO ₃ represents the space group: P4 mm, BaTi ₂ O ₅ is a value obtained by Rietveld analysis using the space group: A / 12m1, unique-b.

≪Relative permittivity≫
An indium-gallium (In-Ga) alloy is applied to the upper and lower surfaces of each dielectric ceramic composition as an electrode, and an LCR meter (4284A manufactured by Agilent, Inc., measurement conditions: AC applied voltage 1.0 V / mm, frequency 1 kHz) is used. The relative dielectric constant was measured. The obtained values are shown in Table 1 and Table 2, respectively. In the evaluation of relative permittivity, when ε is 400 or more, it is determined to be acceptable (described as “◯” in the “determination” item in Tables 1 and 2 below). In Tables 1 and 2, those having ε less than 400 are described as “x”.

≪Capacitance temperature characteristics≫
The capacitance-temperature characteristics were obtained by measuring the capacitance in the temperature range from −55 ° C. to 200 ° C. with respect to the dielectric ceramic compositions of Examples and Comparative Examples. The capacitance was measured by using a digital LCR meter (manufactured by Hewlett-Packard Japan, 4274A) under the conditions of a frequency of 1 kHz and an input signal level of 1 Vrms. And the electrostatic capacitance in the temperature environment from -55 degreeC to 200 degreeC is measured, and the change rate (unit:%) of the electrostatic capacitance in each temperature with respect to the electrostatic capacitance in 25 degreeC is calculated according to the following formula. Then, the capacity temperature change rate (ΔC) at each temperature was examined. Tables 1 and 2 show the maximum value (Max) and the minimum value (Min) of the rate of change in capacity temperature from −55 ° C. to 200 ° C., respectively. In addition, in the evaluation of the capacity-temperature characteristic, it is acceptable when ΔC = ± 22% or less in the range from −55 ° C. to 200 ° C. (“◯” in the item of “determination” in Tables 1 and 2 below) Or “◎”). In Tables 1 and 2, the specific evaluation criteria are as follows.

-Evaluation criteria-
A: Capacity temperature change rate ΔC is within ± 22%, and the difference between the maximum value and the minimum value of ΔC is 35% or less;
◯: Capacity temperature change rate ΔC is within ± 22%, and the difference between the maximum value and the minimum value of ΔC exceeds 35%;
X: Capacity temperature change rate ΔC is out of the range of ± 22%.

  The evaluation results of the dielectric ceramic compositions of Examples and Comparative Examples are shown in Tables 1 and 2 below. In the column of “Comprehensive Judgment” in Table 1 and Table 2 below, those having a relative dielectric constant (ε) of 400 or more and satisfying the capacity-temperature characteristics are defined as “◯” or “◎”. Those not satisfying any one of them were marked with “x”. In Tables 1 and 2, specific evaluation criteria are as follows.

-Evaluation criteria-
A: The relative dielectric constant (ε) is 400 or more, the capacity temperature change rate (ΔC) is within ± 22%, and the difference between the maximum value and the minimum value of ΔC is 35% or less;
◯: The relative dielectric constant (ε) is 400 or more, the capacity temperature change rate (ΔC) is within ± 22%, and the difference between the maximum value and the minimum value of ΔC exceeds 35%;
X: The relative dielectric constant (ε) is less than 400 and / or the capacity temperature change rate (ΔC) is out of the range of ± 22%.

  Moreover, about the dielectric ceramic composition of Examples 1-3 and Comparative Examples 1, 2, and 11, the capacity | capacitance temperature change rate in each temperature was plotted. The results are shown in FIGS. 1 and 2, respectively. In FIGS. 1 and 2, the range indicated by the square frame represented by the two-dot chain line in the graph is from −55 ° C. to 200 ° C. and the rate of change in capacity temperature (ΔC) = ± 22%. is there.

Table 1 shows examples and comparative examples in which the content ratio (x: 1-x) of BaTiO ₃ and BaTi ₂ O ₅ was changed. From the results in Table 1, it was shown that when the value of x is 0.5 or less or 0.8 or more, at least one of the relative dielectric constant and the capacity-temperature characteristic is lowered.

Table 2 above shows examples and comparative examples in which the content of VO was changed. From the results of Table 2, when the content of VO with respect to the composite oxide (xBaTiO _3. (1-x) BaTi ₂ O ₅ ) is 0.1 mol% or less or 1.5 mol% or more, the relative dielectric constant and the capacity temperature It has been shown that at least one of the properties decreases.

In Comparative Example 12 is a dielectric ceramic composition containing a VO with BaTiO ₃ is a ferroelectric material, towards the embodiments of the present invention showed good capacity-temperature characteristic. From such results, it is considered that BaTi ₂ O ₅ contributes to the improvement of the capacity-temperature characteristics in the compositions of the examples according to the present invention.

Claims (6)

Composition formula (1): xBaTiO ₃ .multidot. (1-x) BaTi ₂ O ₅ (wherein x in the composition formula (1) is more than 0.50 and less than 0.80). As a main component,
A dielectric ceramic composition comprising 0.1 mol% and less than 1.5 mol% of VO with respect to 100 mol% of the composite oxide.   The dielectric ceramic composition according to claim 1, further comprising 0.1 mol% or more and 5.0 mol% or less of SiO with respect to 100 mol% of the composite oxide.   The dielectric ceramic composition according to claim 1, further comprising 0.1 mol% or more and 1.0 mol% or less of MnO with respect to 100 mol% of the composite oxide.   The dielectric ceramic composition according to claim 1, further comprising 0.1 mol% or more and 2.0 mol% or less of BaO with respect to 100 mol% of the composite oxide.   The ceramic electronic component containing the dielectric ceramic composition of any one of Claims 1-4. Barium titanate represented by BaTiO ₃ ;
Barium dititanate represented by BaTi ₂ O ₅ ;
A step of mixing a vanadium compound and molding to obtain a molded body;
Firing the molded body at a temperature of 1250 ° C. or lower, and a method for producing a dielectric ceramic composition,
In the step of obtaining the molded body, the molar ratio of the barium titanate to the barium dititanate is in the range of more than 0.50: less than 0.50 to less than 0.80: more than 0.20.
The dielectric ceramic composition, wherein the vanadium compound is added so as to be more than 0.1 mol% and less than 1.5 mol% in terms of VO with respect to a total of 100 mol% of the barium titanate and the barium dititanate. Manufacturing method.