Conductive paste

Abstract

Provided is a conductive paste for an internal electrode, which is capable of maintaining a relatively high coverage rate even if the internal electrode of a laminated ceramic capacitor is thinned. A conductive paste for forming internal electrodes (4, 5) of a multilayer ceramic capacitor (1) manufactured by a firing step, the conductive paste containing a conductive metal powder, a ceramic powder, an organic solvent, and an organic binder, at least a portion of the ceramic powder being a powder containing an ABO3-type oxide having a specific ion radius, the ratio of the ion radius of the element at the A position in ABO3 under the 6 coordination to the ion radius of the metal element contained in the conductive metal powder under the 6 coordination is 0.97-1.02 (inclusive). Preferably, the ABO3-type oxide having a specific ion radius has an ilmenite crystal structure, and the conductive metal powder contains one selected from the group consisting of nickel, copper, silver, and a silver-palladium alloy.

Description

Technical Field

[0001] The present invention relates to a conductive paste, and more particularly to a conductive paste for forming internal electrodes of a multilayer ceramic capacitor. Background Art

[0002] Typically, a multilayer ceramic capacitor comprises a laminate having a plurality of dielectric layers formed of ceramic and a plurality of internal electrodes arranged along the interfaces between the dielectric layers; and a plurality of external electrodes provided on the outer surface of the laminate and electrically connected to the internal electrodes. The internal electrodes comprise a plurality of first internal electrodes and a plurality of second internal electrodes arranged alternately in the stacking direction of the laminate, and the external electrodes comprise a first external electrode electrically connected to the first internal electrodes and a second external electrode electrically connected to the second internal electrodes.

[0003] In order to achieve a compact and high-capacitance multilayer ceramic capacitor with this structure, it is required to thin the dielectric layer and internal electrodes and improve the coverage of the internal electrodes (electrode continuity). Generally speaking, during the firing process when manufacturing multilayer ceramic capacitors, the temperature at which the conductive metal particles contained in the conductive paste film that will become the internal electrodes is sintered is lower than the temperature at which the ceramic constituting the dielectric layer is sintered, so the metal particles contained in the internal electrodes are sintered first. This causes the coverage of the internal electrodes to decrease. In particular, for internal electrodes that are thinned to a thickness of less than 1.0 μm, there is a problem that the coverage is easily reduced, and this reduction in coverage easily hinders the achievement of high capacitance.

[0004] Therefore, in order to achieve high coverage and thinner internal electrodes, it is necessary to further increase the sintering temperature of the conductive metal particles contained in the conductive paste film that will become the internal electrodes during the firing process when manufacturing multilayer ceramic capacitors. This allows the sintering temperature of the metal particles contained in the conductive paste film that will become the internal electrodes to be closer to the temperature at which the ceramic constituting the dielectric layer begins sintering, aligning the shrinkage timing of the internal electrodes and the dielectric layer during sintering. As a result, the internal electrode coverage is increased, enabling higher capacitance.

[0005] According to the above-mentioned method, in order to improve the coverage of the internal electrodes and achieve higher capacitance, it is known to add a ceramic material with a composition similar to that of the ceramic constituting the dielectric layer, i.e., a common material, to the conductive paste used to form the internal electrodes, as described, for example, in paragraph 0004 of Patent Document 1 (Japanese Patent Application Laid-Open No. 2016-31807). The addition of the common material shifts the sintering timing of the metal particles contained in the conductive paste film, which will become the internal electrodes, to a higher temperature, allowing the sintering temperature of the metal particles contained in the conductive paste film to approach the sintering temperature of the ceramic constituting the dielectric layer.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-31807 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] However, even when common materials are added to the conductive paste used to form the internal electrodes, the sintering temperature of the metal particles contained in the conductive paste remains lower than that of the ceramic constituting the dielectric layer, leading to the need for further improvement. In particular, with internal electrodes that have been thinned to, for example, less than 1.0 μm in thickness, there is a strong demand for effective solutions to the reduced coverage that hinders increased capacitance.

[0011] Therefore, the present invention has been made in view of such problems, and an object of the present invention is to provide a conductive paste for forming internal electrodes capable of maintaining a relatively high coverage even when the internal electrodes are thinned.

[0012] Technical solutions to solve problems

[0013] The present invention is directed to a conductive paste for forming internal electrodes of a multilayer ceramic capacitor, comprising conductive metal powder, ceramic powder, an organic solvent, and an organic binder.

[0014] The ceramic powder contained in the conductive paste is used to suppress a decrease in coverage. The inventors of the present application discovered a correlation between the metal constituting the conductive metal powder contained in the conductive paste and the element at the A-site in the ABO3-type oxide constituting the ceramic powder, leading to the completion of the present invention. More specifically, the inventors focused on the ionic radius of the metal constituting the conductive metal powder and the ionic radius of the element at the A-site in the ABO3-type oxide constituting the ceramic powder, and discovered that a ratio of these ionic radii within a given range further contributes to improved coverage of the internal electrodes.

[0015] Furthermore, the appropriate ratio of ionic radii that can contribute to improving the coverage of the internal electrodes is not universal but varies depending on the type of metal constituting the conductive metal powder. However, the inventors of this application have noted that, while the appropriate ratio of ionic radii varies depending on the type of metal constituting the conductive metal powder, there are common elements in the appropriate ratio of ionic radii even among different metal types.

[0016] Therefore, in the present invention, it is characterized in that at least a part of the ceramic powder is a powder of an ABO3 type oxide containing an element at the A position having a specific ionic radius, and is a powder of an ABO3 type oxide in which the ratio of the ionic radius of the element at the A position in ABO3 at 6 coordination to the ionic radius of the metal contained in the conductive metal powder at 6 coordination is greater than 0.97 and less than 1.02.

[0017] Effects of the Invention

[0018] When the conductive paste of the present invention is used to form the internal electrodes of a multilayer ceramic capacitor, the internal electrode coverage can be increased regardless of the type of metal used to form the conductive metal powder. Therefore, even when the internal electrodes are thinned, the internal electrode coverage can be maintained high, ensuring that the increased capacitance of the multilayer ceramic capacitor is not hindered. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 1 is a cross-sectional view schematically showing a multilayer ceramic capacitor 1 to which the conductive paste according to the present invention is applied. DETAILED DESCRIPTION

[0020] Reference Figure 1 Next, the structure of a multilayer ceramic capacitor 1 to which the conductive paste according to the present invention is applied will be described.

[0021] A multilayer ceramic capacitor 1 includes a laminate 2. The laminate 2 includes a plurality of dielectric layers 3 formed of ceramic, and a plurality of internal electrodes 4 and 5 arranged along the interfaces between the plurality of dielectric layers 3. The internal electrodes 4 and 5 are divided into a plurality of first internal electrodes 4 and a plurality of second internal electrodes 5, which are arranged alternately in the stacking direction of the laminate 2. A first external electrode 6 and a second external electrode 7 are provided on the outer surface of the laminate 2, more specifically, on each opposing end surface. The first external electrode 6 is electrically connected to the first internal electrode 4, and the second external electrode 7 is electrically connected to the second internal electrode 5.

[0022] Dielectric layer 3 comprises, for example, a ceramic containing ABO3 (A is at least one of Ba, Ca, and Sr, and B is at least one of Ti and Zr) as a main component. Alternatively, the ceramic may contain ABO3 as a main component and further contain at least one of Mn, Mg, Si, Y, Dy, and Gd as a secondary component.

[0023] The internal electrodes 4 and 5 preferably contain, as a conductive component, one selected from, for example, nickel, copper, silver, and a silver-palladium alloy. Furthermore, as a characteristic composition, the internal electrodes 4 and 5 contain, as a ceramic component, an ABO3-type oxide having a specific ionic radius, wherein the ratio of the ionic radius of the element at the A-position in ABO3 at a six-coordinate position to the ionic radius of the metal element serving as the conductive component at a six-coordinate position is 0.97 to 1.02. The ABO3-type oxide preferably has an ilmenite crystal structure.

[0024] As will be seen in the experimental examples described below, in a preferred embodiment, dielectric layer 3 comprises a ceramic primarily composed of at least one selected from BaTiO3, SrTiO3, and CaZrO3. In this case, internal electrodes 4 and 5 may further comprise, as a ceramic component, at least one selected from BaTiO3, SrTiO3, and CaZrO3 contained in dielectric layer 3, in addition to the aforementioned ABO3-type oxide having a specific ionic radius, as needed.

[0025] The content of the ceramic component in the internal electrodes 4 and 5 is preferably selected to be 5% by mass or more and 15% by mass or less. The content is calculated as {(mass of the ceramic component) / (mass of the ceramic component + mass of the conductive metal or alloy containing the conductive metal)} × 100 (the same applies hereinafter).

[0026] For example, a conductive paste containing Ag or Cu as a main conductive component is applied to the end surfaces of the laminate 2 and then fired to form the external electrodes 6 and 7. If necessary, the thick film formed by firing may be plated with, for example, Ni, and then plated with Sn.

[0027] The multilayer ceramic capacitor 1 is manufactured, for example, through the following process. First, a ceramic slurry containing raw material powder of a ceramic having the composition described above is prepared. Next, an appropriate sheet forming method is applied to the ceramic slurry to form ceramic green sheets. Next, a conductive paste to be used as the internal electrodes 4 and 5 is applied to a given ceramic green sheet among the plurality of ceramic green sheets by printing or the like. Next, the plurality of ceramic green sheets are stacked and then press-bonded to obtain an unprocessed stack. Next, the unprocessed stack is fired. In this firing process, the ceramic green sheet becomes the dielectric layer 3. Then, external electrodes 6 and 7 are formed on the end faces of the stack 2.

[0028] The conductive paste to be used as the internal electrodes 4 and 5 when manufacturing the above-described multilayer ceramic capacitor 1 is preferably prepared as follows.

[0029] When making a conductive paste, the following steps are implemented: the first step is to prepare a ceramic powder slurry containing ceramic powder, an organic solvent and a dispersant; the second step is to prepare a metal powder slurry containing conductive metal powder, an organic solvent and a dispersant; the third step is to prepare an organic carrier containing an organic resin component and an organic solvent; and the fourth step is to mix the above-mentioned ceramic powder slurry, metal powder slurry and organic carrier.

[0030] More specifically, in the first step, ceramic powder and a dispersant are mixed in an organic solvent to prepare a ceramic powder slurry.

[0031] The ceramic powder can be composed of an ABO3-type oxide having the aforementioned specific ionic radius. Furthermore, a powder containing at least one selected from BaTiO3, SrTiO3, and CaZrO3 as a common material may also be used. When using a powder containing at least one selected from BaTiO3, SrTiO3, and CaZrO3, preferably, at least 10% by volume of the ceramic powder consists of a powder containing an ABO3-type oxide having the aforementioned specific ionic radius, with the remainder of the ceramic powder consisting primarily of at least one selected from BaTiO3, SrTiO3, and CaZrO3.

[0032] The ABO3-type oxide of a specific ionic radius is determined based on the type of metal constituting the conductive metal powder contained in the metal powder slurry prepared in the second step described below. Specifically, the ABO3-type oxide of a specific ionic radius is determined by determining the ionic radius of the metal contained in the conductive metal powder at a hexacoordinate level, and setting the A-site element as the element whose ionic radius at a hexacoordinate level relative to the ionic radius is 0.97 to 1.02. The range of 0.97 to 1.02 for the ionic radius ratio was derived based on experimental results described below.

[0033] As described above, ceramic powder containing an ABO3-type oxide with a specific ionic radius can suppress potential reactions with the conductive metal powder contained in the metal powder slurry produced in the second step during firing. The ceramic powder contained in the conductive paste can also contain the aforementioned ABO3 oxide as a main component and at least one of Mn, Mg, Si, Y, Dy, and Gd as a secondary component. Including such secondary components can suppress the growth of ceramic particles and can sometimes further effectively suppress the sintering of metal particles.

[0034] As the dispersant to be mixed with the ceramic powder in the first step, for example, an anionic polymer dispersant can be used, and as the organic solvent, for example, dihydroterpineol can be used.

[0035] In the second step, a metal powder slurry is prepared by mixing a conductive metal powder and a dispersant in an organic solvent. For example, the conductive metal powder may be a powder containing one selected from nickel, copper, silver, and a silver-palladium alloy. The dispersant and organic solvent used in the second step can be the same as those used in the first step.

[0036] In the third step, an organic vehicle is prepared by mixing an organic resin component with an organic solvent. For example, ethyl cellulose resin can be used as the organic resin component. The organic solvent used in the third step can be the same as that used in the first step.

[0037] In the fourth step, the ceramic powder slurry, metal powder slurry, and organic vehicle are mixed. This produces a conductive paste that will become the internal electrodes 4 and 5. This conductive paste contains the ceramic powder slurry. As described above, the ceramic powder slurry includes ceramic powder containing an ABO3 oxide with a specific ionic radius. Therefore, after the firing step, the internal electrodes 4 and 5 of the multilayer ceramic capacitor 1 manufactured will contain an ABO3 oxide with a specific ionic radius.

[0038] Preferably, the content of the ceramic powder in the conductive paste is selected to be 5 mass % or more and 15 mass % or less.

[0039] Next, experimental examples conducted to determine the scope of the present invention and to confirm the effects of the present invention will be described.

[0040] [Experimental Example 1] Conductive metal powder: nickel powder

[0041] In Experimental Example 1, nickel powder was prepared as the conductive metal powder contained in the conductive paste for forming the internal electrode.

[0042] Meanwhile, NiTiO3, MgTiO3, and MnTiO3 were prepared as ABO3 oxides with specific ionic radii for the ceramic powder contained in the conductive paste for forming the internal electrodes. CuTiO3, BaTiO3, CaZrO3, and SrTiO3 were also prepared as other ABO3 oxides. Table 1 shows the "crystal structure," "coordination number," "A-site element," and "ionic radius" for these ABO3 oxides. Ba, Ca, and Sr have a 12-coordinated structure in their original perovskite structure. However, Ba, Ca, and Sr also have a 6-coordinated structure when dissolved in the ilmenite structure at the sites of the 6-coordinated elements (Ni, Mg, and Mn). Therefore, the "ionic radius" in Table 1 shows the values ​​for the 6-coordinated structure.

[0043] [Table 1]

[0044]

[0045] Hereinafter, Experimental Examples 1-1, 1-2, and 1-3, which were carried out by changing the ceramic raw materials constituting the dielectric layer, will be described.

[0046] (Experimental Example 1-1) Main component of ceramic constituting the dielectric layer: BaTiO3

[0047] 1-1-1. Preparation of BaTiO3-based ceramic raw materials constituting the dielectric layer

[0048] As starting materials, powders of BaCO₃ and TiO₂, the main components, were weighed and mixed in a ball mill for 72 hours, followed by heat treatment at a maximum temperature of 1000°C for 2 hours to obtain a heat-treated powder. Separately, powders of MnO, Dy₂O₃, MgO, SiO₂, and BaCO₃ were prepared as auxiliary components and weighed so that the auxiliary component powders had a composition ratio of 100%BaTiO₃ + 0.5%Mn + 1.0%Dy + 1.0%Mg + 1.0%Si + 2.0%Ba relative to the heat-treated powder. These auxiliary component powders were added to the heat-treated powder, mixed in a ball mill for 24 hours, and then dried to obtain a BaTiO₃-based ceramic raw material powder.

[0049] 1-1-2. Preparation of Conductive Paste for Internal Electrode Formation

[0050] As ceramic powder contained in the conductive paste for forming the internal electrode, powder of "ABO 3 oxide" shown in Table 2 described later and BaTiO 3 -based ceramic raw material powder for the above-mentioned dielectric layer were used.

[0051] The powders of these "ABO3 oxides" and the BaTiO3-based ceramic raw material powder were weighed to obtain the "addition ratios" shown in Table 2. These powders, dihydroterpineol as an organic solvent, and an anionic polymer dispersant as a dispersant were premixed using a medium-free agitated mill, and then dispersed using a medium-agitated mill to prepare a ceramic powder slurry (first step).

[0052] Meanwhile, nickel powder as a conductive metal powder, dihydroterpineol as an organic solvent, and an anionic polymer dispersant as a dispersant were dispersed using a three-roll mill to prepare a metal powder slurry (second step).

[0053] Furthermore, ethyl cellulose resin as an organic resin component and dihydroterpineol as an organic solvent were mixed to obtain an organic vehicle (third step).

[0054] Next, the metal powder slurry and the ceramic powder slurry were added to the organic vehicle, mixed, and dispersed to prepare a conductive paste for forming an internal electrode (fourth step).

[0055] Here, the content of the ceramic powder in the conductive paste for forming the internal electrode was set to 10% by mass.

[0056] Table 2 shows the ratio of the ionic radius of the A-site element at six coordination levels to the ionic radius of nickel to be included in the internal electrode at six coordination levels, i.e., the "Ionic Radius Ratio (A-site Element / Metal Nickel)." Furthermore, for Sample 8, the ratio of the Ba ionic radius at six coordination levels (1.35 Å) shown in Table 1 to the Ni ionic radius at six coordination levels (0.69 Å) is shown.

[0057] 1-1-3. Fabrication of Multilayer Ceramic Capacitors

[0058] A ceramic slurry containing the BaTiO3-based ceramic raw material powder prepared in 1-1-1 above was prepared, and then a scraper method was applied to the ceramic slurry to form ceramic green sheets. Next, the conductive paste for forming internal electrodes prepared in 1-1-2 above was applied to a given ceramic green sheet among the plurality of ceramic green sheets by screen printing. Next, the plurality of ceramic green sheets were stacked and then press-bonded to obtain an unprocessed laminate. Next, the unprocessed laminate was fired. Then, external electrodes were formed on the end faces of the sintered laminate to produce a sample laminated ceramic capacitor.

[0059] 1-1-4. Evaluation

[0060] [Table 2]

[0061]

[0062] The internal electrodes and the dielectric layer located at the center in the height direction of the laminated body of the sample laminated ceramic capacitor were separated from each other by electric field peeling.

[0063] Next, the exposed internal electrode's center (the area halfway along the width and halfway along the length) was observed using a microscope at 100x magnification. The resulting image was analyzed to determine the ratio of the area occupied by the conductor film, which serves as the internal electrode, in the exposed portion. This ratio is reported as the "coverage" in Table 2. Samples with a "coverage" exceeding 80% were rated as good and marked with "○" in the "Evaluation" column. Samples with a "coverage" of 80% or less were rated as poor and marked with "×" in the "Evaluation" column.

[0064] 1-1-5. Investigation

[0065] Samples 1 to 3 and 5 to 7 in Table 2 were rated "O." In these samples 1 to 3 and 5 to 7, the internal electrodes contained any of NiTiO3, MgTiO3, and MnTiO3 as the ABO3 oxide. Furthermore, the internal electrodes contained nickel as a conductive component.

[0066] Here, focusing on ionic radius, as shown in the "NiTiO3" column in Table 1, the ionic radius of nickel at the hexacoordinate level is 0.69 Å. Meanwhile, as shown in Table 1, the ionic radius of the hexacoordinated element of NiTiO3, MgTiO3, and MnTiO3, the ABO3 oxides included in the internal electrodes of Samples 1 to 3 and 5 to 7, at the hexacoordinate level are 0.69 Å, 0.72 Å, and 0.67 Å, ​​respectively.

[0067] In samples 1 to 3 and 5 to 7 evaluated as "○", the ratio of the ionic radius of the element at the A site in ABO3 in hexacoordinate to the ionic radius of the metal element contained in the conductive metal particles in hexacoordinate, i.e., the "ionic radius ratio" was 0.97 or more and 1.04 or less.

[0068] As such, for NiTiO₃, MgTiO₃, and MnTiO₃, the ABO₃ oxides in Samples 1-3 and 5-7, the ionic radius of the A-site element in the ABO₃ at a six-coordinate position is equal to or similar to the ionic radius of nickel, the conductive metal to be contained in the internal electrode. Therefore, the energy difference with the nickel in the internal electrode is zero or minimal. Therefore, the element is not expelled from the internal electrode but remains, contributing to the improvement of the internal electrode's heat resistance. As a result, it is estimated that the coverage rate in Samples 1-3 and 5-7 increased to 84% or more.

[0069] Furthermore, as in Samples 5 to 7, the addition ratio of NiTiO3, MgTiO3, and MnTiO3 does not necessarily have to be 100%. As long as it is 10% or more, an effect of improving coverage can be confirmed compared to the case where none of NiTiO3, MgTiO3, and MnTiO3 is included. Furthermore, it is noted that in Experimental Example 1-1, the coverage of Samples 5 to 7, in which the addition ratio of NiTiO3, MgTiO3, and MnTiO3 was 10%, was equivalent to the coverage of Samples 1 to 3, in which the addition ratio was 100%.

[0070] In contrast, Sample 4, which received an "X" rating, used CuTiO as the ABO oxide. As shown in Table 1, the ionic radius of Cu, the A-site element in ABO, at a hexacoordinated position is 0.73 Å. Therefore, the ratio of the ionic radius of Cu at a hexacoordinated position to the ionic radius of nickel at a hexacoordinated position, or the "ionic radius ratio," was 1.06. In other words, the "ionic radius ratio" fell outside the range of 0.97 to 1.04, and the coverage dropped to 75%.

[0071] In addition, in sample 8, which was also evaluated as "×", only BaTiO3, a common material, was added to the internal electrode. In this case, although Ba, as an element at the A site in the ABO3 of the perovskite structure, is 12-coordinated, when solid-dissolved in the A site of the ilmenite structure, it is necessary to compare the ionic radius at the 6-coordinated position, which is the coordination number of the A site in the ilmenite structure. As shown in Table 1, the ionic radius of Ba at the 6-coordinated position is 1.35Å. Therefore, the ratio of the ionic radius of Ba at the 6-coordinated position to the ionic radius of nickel at the 6-coordinated position, that is, the "ionic radius ratio", is 1.96. Therefore, the "ionic radius ratio" deviates from the range of 0.97 or more and 1.04 or less, and the coverage rate drops to 74%.

[0072] In samples 4 and 8, the "ion radius ratio" deviated from the range of 0.97 to 1.04, and CuTiO 3 and BaTiO 3 were respectively discharged from the internal electrode portion, and the heat resistance of the internal electrode was not improved. It is presumed that the coverage was reduced.

[0073] (Experimental Example 1-2) Main component of ceramic constituting the dielectric layer: CaZrO3

[0074] 1-2-1. Preparation of CaZrO3-based ceramic raw materials constituting the dielectric layer

[0075] As starting materials, powders of CaCO3 and ZrO2 as main components and powders of MnO, SiO2 and MgO as auxiliary components were weighed, mixed for 72 hours in a ball mill, and then heat treated at a maximum temperature of 1000°C for 2 hours to obtain CaZrO3-based ceramic raw material powder.

[0076] 1-2-2. Preparation of Conductive Paste for Internal Electrode Formation

[0077] As ceramic powder contained in the conductive paste for forming the internal electrode, powder of "ABO 3 oxide" shown in Table 3 described later and CaZrO 3 -based ceramic raw material powder for the above-mentioned dielectric layer were used.

[0078] The powders of these "ABO3 oxides" and the CaZrO3-based ceramic raw material powder were weighed to give the "addition ratios" shown in Table 3, and a conductive paste for forming internal electrodes was prepared through the same steps as in the above-mentioned Experimental Example 1-1.

[0079] Here, the content of the ceramic powder in the conductive paste for forming the internal electrode was set to 10% by mass.

[0080] Table 3 shows the "Ionic Radius Ratio (A-site Element / Metal Nickel)" as in Table 2. Furthermore, for Sample 18, the ratio of the Ca ionic radius (1.00 Å) at a hexacoordinated position, as shown in Table 1, to the Ni ionic radius (0.69 Å) at a hexacoordinated position is shown.

[0081] 1-2-3. Fabrication of Multilayer Ceramic Capacitors

[0082] A ceramic slurry containing the CaZrO3-based ceramic raw material powder prepared in step 1 was prepared. Next, the ceramic slurry was subjected to a doctor blade method to form ceramic green sheets. Subsequently, a sample multilayer ceramic capacitor was produced through the same steps as in Experimental Example 1-1.

[0083] 1-2-4. Evaluation

[0084] [Table 3]

[0085]

[0086] According to the same procedure as in the case of Experimental Example 1-1, the “coverage ratio” was determined as shown in Table 3, and the evaluation was performed in the same manner.

[0087] 1-2-5. Investigation

[0088] Samples 11 to 13 and 15 to 17 in Table 3 were rated "O." In these samples 11 to 13 and 15 to 17, the internal electrodes contained any of NiTiO3, MgTiO3, and MnTiO3 as the ABO3 oxide. Furthermore, the internal electrodes contained nickel as a conductive component.

[0089] Here, focusing on ionic radius, as shown in the "NiTiO3" column in Table 1, the ionic radius of nickel at the hexacoordinate level is 0.69 Å. Meanwhile, as shown in Table 1, the ionic radius of the hexacoordinated element of NiTiO3, MgTiO3, and MnTiO3, the ABO3 oxides included in the internal electrodes of Samples 11 to 13 and 15 to 17, at the hexacoordinate level are 0.69 Å, 0.72 Å, and 0.67 Å, ​​respectively.

[0090] In samples 11 to 13 and 15 to 17 evaluated as "○", the ratio of the ionic radius of the element at the A site in ABO3 at 6 coordination to the ionic radius of the metal element contained in the conductive metal particles at 6 coordination, i.e., the "ionic radius ratio" was 0.97 or more and 1.04 or less.

[0091] As shown in this way, with respect to NiTiO3, MgTiO3 and MnTiO3 as ABO3 oxides in samples 11 to 13 and 15 to 17, the ionic radius of the element at the A position in ABO3 at a 6-coordinate position is equal to or close to the ionic radius of nickel as a conductive metal that should be included in the internal electrode at a 6-coordinate position. Therefore, the energy difference with the nickel in the internal electrode is 0 or small, so it is not discharged from the internal electrode portion but remains and plays a role, thereby improving the heat resistance of the internal electrode. As a result, in samples 11 to 13 and 15 to 17, it can be inferred that the coverage is increased to more than 81%.

[0092] In addition, as in samples 15 to 17, the addition ratio of NiTiO3, MgTiO3 and MnTiO3 does not necessarily have to be 100%. As long as it is above 10%, the effect of improved coverage can be confirmed compared with the case where none of NiTiO3, MgTiO3 and MnTiO3 is included.

[0093] In contrast, Sample 14, which received an "X" rating, used CuTiO as the ABO oxide. As shown in Table 1, the ionic radius of Cu, the A-site element in ABO, at a hexacoordinated position is 0.73 Å. Therefore, the ratio of the ionic radius of Cu at a hexacoordinated position to the ionic radius of nickel at a hexacoordinated position, or the "ionic radius ratio," was 1.06. In other words, the "ionic radius ratio" fell outside the range of 0.97 to 1.04, and the coverage dropped to 75%.

[0094] In addition, in sample 18, which was also evaluated as "×", only CaZrO3, a common material, was added to the internal electrode. In this case, although Ca, as an element at the A site in the ABO3 of the perovskite structure, is 12-coordinated, when solid-dissolved in the A site of the ilmenite structure, it is necessary to compare the ionic radius at the 6-coordinated position, which is the coordination number of the A site in the ilmenite structure. As shown in Table 1, the ionic radius of Ca at the 6-coordinated position is 1.00Å. Therefore, the ratio of the ionic radius of Ca at the 6-coordinated position to the ionic radius of nickel at the 6-coordinated position, i.e., the "ionic radius ratio", is 1.45. As a result, the "ionic radius ratio" deviates from the range of 0.97 or more and 1.04 or less, and the coverage rate drops to 72%.

[0095] In samples 14 and 18, the "ion radius ratio" deviated from the range of 0.97 to 1.04, and CuTiO 3 and CaZrO 3 were respectively discharged from the internal electrode portion, and the heat resistance of the internal electrode was not improved. It is presumed that the coverage was reduced.

[0096] (Experimental Example 1-3) Main component of ceramic constituting the dielectric layer: SrTiO3

[0097] 1-3-1. Preparation of SrTiO3-based ceramic raw materials constituting the dielectric layer

[0098] As starting materials, powders of SrCO3 and TiO2 as main components and powders of MnO, SiO2 and MgO as auxiliary components were weighed, mixed for 72 hours in a ball mill, and then heat treated at a maximum temperature of 1000°C for 2 hours to obtain SrTiO3-based ceramic raw material powder.

[0099] 1-3-2. Preparation of Conductive Paste for Internal Electrode Formation

[0100] As ceramic powder contained in the conductive paste for forming the internal electrode, powder of "ABO 3 oxide" shown in Table 4 described later and SrTiO 3 -based ceramic raw material powder for the above-mentioned dielectric layer were used.

[0101] The powders of these "ABO3 oxides" and the SrTiO3-based ceramic raw material powder were weighed to obtain the "addition ratios" shown in Table 4, and a conductive paste for forming internal electrodes was prepared through the same steps as in the above-mentioned Experimental Example 1-1.

[0102] Here, the content of the ceramic powder in the conductive paste for forming the internal electrode was set to 10% by mass.

[0103] Table 4 shows the "Ionic Radius Ratio (A-site Element / Metal Nickel)" as in Table 2. Furthermore, for Sample 28, the ratio of the Sr ionic radius (1.18 Å) at a hexacoordinated position, as shown in Table 1, to the Ni ionic radius (0.69 Å) at a hexacoordinated position is shown.

[0104] 1-3-3. Fabrication of Multilayer Ceramic Capacitors

[0105] A ceramic slurry containing the SrTiO3-based ceramic raw material powder prepared in step 1 was prepared. Next, the ceramic slurry was subjected to a doctor blade method to form ceramic green sheets. Subsequently, a sample multilayer ceramic capacitor was produced through the same steps as in Experimental Example 1-1.

[0106] 1-3-4. Evaluation

[0107] [Table 4]

[0108]

[0109] According to the same procedure as in the case of Experimental Example 1-1, the “coverage ratio” was determined as shown in Table 4, and the evaluation was performed in the same manner.

[0110] 1-3-5. Investigation

[0111] Samples 21 to 23 and 25 to 27 in Table 4 were rated "O." In these samples 21 to 23 and 25 to 27, the internal electrodes contained any of NiTiO3, MgTiO3, and MnTiO3 as the ABO3 oxide. Furthermore, the internal electrodes contained nickel as a conductive component.

[0112] Here, focusing on ionic radius, as shown in the "NiTiO3" column in Table 1, the ionic radius of nickel at the hexacoordinate level is 0.69 Å. Meanwhile, as shown in Table 1, the ionic radius of the hexacoordinated element of NiTiO3, MgTiO3, and MnTiO3, the ABO3 oxides included in the internal electrodes of Samples 21 to 23 and 25 to 27, at the hexacoordinate level are 0.69 Å, 0.72 Å, and 0.67 Å, ​​respectively.

[0113] In samples 21 to 23 and 25 to 27 evaluated as "○", the ratio of the ionic radius of the element at the A position in ABO3 at 6 coordination to the ionic radius of the metal element contained in the conductive metal particles at 6 coordination, i.e., the "ionic radius ratio" was 0.97 or more and 1.04 or less.

[0114] As shown in this way, regarding NiTiO3, MgTiO3 and MnTiO3 as ABO3 oxides in samples 21 to 23 and 25 to 27, the ionic radius of the element at the A position in ABO3 at 6 coordination is equal to or close to the ionic radius of nickel as a conductive metal that should be included in the internal electrode at 6 coordination. Therefore, the energy difference with the nickel in the internal electrode is 0 or small, so it is not discharged from the internal electrode part but remains and plays a role, thereby improving the heat resistance of the internal electrode. As a result, in samples 21 to 23 and 25 to 27, it can be inferred that the coverage exceeds 80%.

[0115] In addition, as in samples 25 to 27, the addition ratio of NiTiO3, MgTiO3 and MnTiO3 does not necessarily have to be 100%. As long as it is above 10%, the effect of improved coverage can be confirmed compared with the case where none of NiTiO3, MgTiO3 and MnTiO3 is included.

[0116] In contrast, Sample 24, which received an "X" rating, used CuTiO as the ABO oxide. As shown in Table 1, the ionic radius of Cu, the A-site element in ABO, at a hexacoordinated position is 0.73 Å. Therefore, the ratio of the ionic radius of Cu at a hexacoordinated position to the ionic radius of nickel at a hexacoordinated position, or the "ionic radius ratio," was 1.06. This means that the "ionic radius ratio" fell outside the range of 0.97 to 1.04, and the coverage dropped to 72%.

[0117] In addition, in sample 28, which was also evaluated as "×", only SrTiO3, a common material, was added to the internal electrode. In this case, although Sr, as an element at the A site in the ABO3 perovskite structure, is 12-coordinated, when solid-dissolved in the A site of the ilmenite structure, it is necessary to compare the ionic radius at the 6-coordinated position, which is the coordination number of the A site in the ilmenite structure. As shown in Table 1, the ionic radius of Sr at the 6-coordinated position is 1.18Å. Therefore, the ratio of the ionic radius of Sr at the 6-coordinated position to the ionic radius of nickel at the 6-coordinated position, i.e., the "ionic radius ratio", is 1.71. As a result, the "ionic radius ratio" deviates from the range of 0.97 or more and 1.04 or less, and the coverage rate drops to 70%.

[0118] In samples 24 and 28, the "ion radius ratio" was outside the range of 0.97 to 1.04, and CuTiO 3 and SrTiO 3 were respectively discharged from the internal electrode portion, and the heat resistance of the internal electrode was not improved. It is presumed that the coverage was reduced.

[0119] [Experimental Example 2] Conductive Metal Powder: Copper Powder

[0120] In Experimental Example 2, copper powder was prepared as the conductive metal powder contained in the conductive paste for forming the internal electrode.

[0121] Meanwhile, CuTiO3, CoTiO3, and CrTiO3 were prepared as ABO3 oxides with specific ionic radii for the ceramic powder contained in the conductive paste for forming the internal electrodes. BaTiO3, CaZrO3, and SrTiO3 were also prepared as other ABO3 oxides. Table 5 shows the "crystal structure," "coordination number," "A-site element," and "ionic radius" for these ABO3 oxides. Ba, Ca, and Sr have a 12-coordinated structure in their original perovskite structure. However, Ba, Ca, and Sr also have a 6-coordinated structure when dissolved in the ilmenite structure at the sites of the 6-coordinated elements (Cu, Co, and Cr). Therefore, the "ionic radius" in Table 5 shows the values ​​for the 6-coordinated structure.

[0122] [Table 5]

[0123]

[0124] Hereinafter, Experimental Example 2-1, Experimental Example 2-2, and Experimental Example 2-3, which were carried out by changing the ceramic raw material constituting the dielectric layer, will be described.

[0125] (Experimental Example 2-1) Main component of ceramic constituting the dielectric layer: BaTiO3

[0126] 2-1-1. Preparation of BaTiO3-based ceramic raw materials constituting the dielectric layer

[0127] Through the same steps as in Experimental Example 1-1, BaTiO3-based ceramic raw material powder was obtained.

[0128] 2-1-2. Preparation of Conductive Paste for Internal Electrode Formation

[0129] As ceramic powders contained in the conductive paste for forming the internal electrode, powders of "ABO 3 oxides" shown in Table 6 described later and BaTiO 3 -based ceramic raw material powders for the above-mentioned dielectric layers were used.

[0130] The powders of these "ABO3 oxides" and the BaTiO3-based ceramic raw material powder were weighed to obtain the "addition ratios" shown in Table 6, and a conductive paste for forming internal electrodes was prepared through the same steps as in the above-mentioned Experimental Example 1-1.

[0131] Here, the content of the ceramic powder in the conductive paste for forming the internal electrode was set to 10% by mass.

[0132] Table 6 shows the ratio of the ionic radius of the A-site element at six coordination levels to the ionic radius of the copper to be included in the internal electrode at six coordination levels, i.e., the "Ionic Radius Ratio (A-site Element / Metallic Copper)." Furthermore, for Sample 37, the ratio of the Ba element's ionic radius at six coordination levels (1.35 Å) shown in Table 5 to the copper's ionic radius at six coordination levels (0.77 Å) is shown.

[0133] 2-1-3. Manufacturing Multilayer Ceramic Capacitors

[0134] A ceramic slurry containing the BaTiO3-based ceramic raw material powder prepared in step 1 was prepared. Next, the ceramic slurry was subjected to a doctor blade method to form ceramic green sheets. Subsequently, a sample multilayer ceramic capacitor was produced through the same steps as in Experimental Example 1-1.

[0135] 2-1-4. Evaluation

[0136] [Table 6]

[0137]

[0138] According to the same procedure as in the case of Experimental Example 1-1, the “coverage ratio” was determined as shown in Table 6, and the evaluation was performed in the same manner.

[0139] 2-1-5. Investigation

[0140] Samples 31 to 36 in Table 6 were rated "O." In these samples 31 to 36, the internal electrodes contained any of CuTiO 3 , CoTiO 3 , and CrTiO 3 as the ABO 3 oxide. Furthermore, the internal electrodes contained copper as the conductive component.

[0141] Here, focusing on ionic radius, as shown in the "CuTiO3" column in Table 5, the ionic radius of copper at the hexacoordinate level is 0.77 Å. Meanwhile, as shown in Table 5, the ionic radius of the hexacoordinated element of CuTiO3, CoTiO3, and CrTiO3, the ABO3 oxides included in the internal electrodes of Samples 31 to 36, at the hexacoordinate level are 0.77 Å, 0.74 Å, and 0.80 Å, respectively.

[0142] In samples 31 to 36 evaluated as "○", the "ionic radius ratio", which is the ratio of the ionic radius of the element at the A site in ABO3 in hexacoordinate to the ionic radius of copper in hexacoordinate, was 0.96 or more and 1.04 or less.

[0143] As such, for the ABO3 oxides CuTiO3, CoTiO3, and CrTiO3 in Samples 31 to 36, the ionic radius of the A-site element in ABO3 at a six-coordinate position is equal to or similar to the ionic radius of copper, the conductive metal to be contained in the internal electrodes. Therefore, the energy difference with the copper in the internal electrodes is zero or minimal. Therefore, the element is not expelled from the internal electrodes but remains, contributing to the improvement of the internal electrode's heat resistance. As a result, it is estimated that the coverage rate in Samples 31 to 36 increased to 84% or more.

[0144] Furthermore, as in Samples 34 to 36, the addition ratio of CuTiO₃, CoTiO₃, and CrTiO₃ does not necessarily have to be 100%. As long as it is 10% or more, an effect of improving coverage can be confirmed compared to the case where none of CuTiO₃, CoTiO₃, and CrTiO₃ is included. Furthermore, it is noted that in Experimental Example 2-1, the coverage of Samples 34 to 36, in which the addition ratio of CuTiO₃, CoTiO₃, and CrTiO₃ was 10%, was equivalent to the coverage of Samples 31 to 33, in which the addition ratio was 100%.

[0145] In contrast, in Sample 37, which was evaluated as "×," only BaTiO3, a common material, was added to the internal electrode. In this case, although Ba, as an element at the A site in the ABO3 perovskite structure, is 12-coordinated, when solid-dissolved in the A site of the ilmenite structure, it is necessary to compare the ionic radius at the 6-coordinated position, which is the coordination number of the A site in the ilmenite structure. As shown in Table 5, the ionic radius of Ba at the 6-coordinated position is 1.35 Å. Therefore, the ratio of the ionic radius of Ba at the 6-coordinated position to the ionic radius of copper at the 6-coordinated position, i.e., the "ionic radius ratio," is 1.75. As a result, the "ionic radius ratio" deviates from the range of 0.96 to 1.04, and the coverage rate drops to 74%.

[0146] In Sample 37, the "ion radius ratio" was outside the range of 0.96 to 1.04, BaTiO 3 was partially discharged from the internal electrode, and the heat resistance of the internal electrode was not improved. It is presumed that the coverage was reduced.

[0147] (Experimental Example 2-2) Main component of ceramic constituting the dielectric layer: CaZrO3

[0148] 2-2-1. Preparation of CaZrO3-based ceramic raw materials constituting the dielectric layer

[0149] Through the same steps as in Experimental Example 1-2, a CaZrO3-based ceramic raw material powder was obtained.

[0150] 2-2-2. Preparation of Conductive Paste for Internal Electrode Formation

[0151] As ceramic powders contained in the conductive paste for forming the internal electrode, powders of "ABO 3 oxides" shown in Table 7 described later and CaZrO 3 -based ceramic raw material powders for the above-mentioned dielectric layers were used.

[0152] The powders of these "ABO3 oxides" and the CaZrO3-based ceramic raw material powder were weighed to obtain the "addition ratios" shown in Table 7, and a conductive paste for forming internal electrodes was prepared through the same steps as in the above-mentioned Experimental Example 2-1.

[0153] Here, the content of the ceramic powder in the conductive paste for forming the internal electrode was set to 10% by mass.

[0154] Table 7 shows the "Ionic Radius Ratio (A-site Element / Metallic Copper)" as in Table 6. Furthermore, for Sample 47, the ratio of the Ca element's ionic radius (1.00 Å) at a hexacoordinated position, as shown in Table 5, to the copper element's ionic radius (0.77 Å) at a hexacoordinated position is shown.

[0155] 2-2-3. Manufacturing Multilayer Ceramic Capacitors

[0156] A ceramic slurry containing the CaZrO3-based ceramic raw material powder prepared in step 1 was prepared. Next, the ceramic slurry was subjected to a doctor blade method to form ceramic green sheets. Subsequently, a sample multilayer ceramic capacitor was produced through the same steps as in Experimental Example 2-1.

[0157] 2-2-4. Evaluation

[0158] [Table 7]

[0159]

[0160] According to the same procedure as in the case of Experimental Example 2-1, the “coverage ratio” was determined as shown in Table 7, and the evaluation was performed in the same manner.

[0161] 2-2-5. Inspection

[0162] Samples 41 to 46 in Table 7 were rated "O." In these samples 41 to 46, the internal electrodes contained any of CuTiO 3 , CoTiO 3 , and CrTiO 3 as the ABO 3 oxide. Furthermore, the internal electrodes contained copper as the conductive component.

[0163] Here, focusing on ionic radius, as shown in the "CuTiO3" column in Table 5, the ionic radius of copper at a hexacoordinate position is 0.77 Å. Meanwhile, as shown in Table 5, the ionic radius of the hexacoordinate element of CuTiO3, CoTiO3, and CrTiO3, the ABO3 oxides included in the internal electrodes of Samples 41 to 46, at a hexacoordinate position are 0.77 Å, 0.74 Å, and 0.80 Å, respectively.

[0164] In samples 41 to 46 evaluated as "○", the "ionic radius ratio", which is the ratio of the ionic radius of the element at the A site in ABO3 in hexacoordinate to the ionic radius of copper in hexacoordinate, was 0.96 or more and 1.04 or less.

[0165] As shown in this way, regarding CuTiO3, CoTiO3 and CrTiO3 as ABO3 oxides in samples 41 to 46, the ionic radius of the element at the A position in ABO3 at 6 coordination is equal to or close to the ionic radius of copper as a conductive metal to be contained in the internal electrode at 6 coordination. Therefore, the energy difference with the copper in the internal electrode is 0 or small, so it is not discharged from the internal electrode part but remains and plays a role, thereby improving the heat resistance of the internal electrode. As a result, in samples 41 to 46, it can be inferred that the coverage is increased to more than 81%.

[0166] In addition, as in samples 44 to 46, the addition ratio of CuTiO3, CoTiO3 and CrTiO3 does not necessarily have to be 100%. As long as it is 10% or more, the effect of improved coverage can be confirmed compared with the case where none of CuTiO3, CoTiO3 and CrTiO3 is included.

[0167] In contrast, in Sample 47, which was evaluated as "×," only CaZrO3, a common material, was added to the internal electrode. In this case, although Ca, as an element at the A site in the ABO3 perovskite structure, is 12-coordinated, when solid-dissolved in the A site of the ilmenite structure, it is necessary to compare the ionic radius at the 6-coordinated position, which is the coordination number of the A site in the ilmenite structure. As shown in Table 5, the ionic radius of Ca at the 6-coordinated position is 1.00 Å. Therefore, the ratio of the ionic radius of Ca at the 6-coordinated position to the ionic radius of copper at the 6-coordinated position, i.e., the "ionic radius ratio," is 1.30. As a result, the "ionic radius ratio" deviates from the range of 0.96 to 1.04, and the coverage rate drops to 72%.

[0168] In Sample 47, the "ion radius ratio" was outside the range of 0.96 to 1.04, CaZrO 3 was partially discharged from the internal electrode, and the heat resistance of the internal electrode was not improved. This is presumably because the coverage was reduced.

[0169] (Experimental Example 2-3) Main component of ceramic constituting the dielectric layer: SrTiO3

[0170] 2-3-1. Preparation of SrTiO3-based ceramic raw materials constituting the dielectric layer

[0171] Through the same steps as in Experimental Example 1-3, SrTiO3-based ceramic raw material powder was obtained.

[0172] 2-3-2. Preparation of Conductive Paste for Internal Electrode Formation

[0173] As ceramic powders contained in the conductive paste for forming the internal electrode, powders of "ABO 3 oxides" shown in Table 8 described later and SrTiO 3 -based ceramic raw material powders for the above-mentioned dielectric layers were used.

[0174] The powders of these "ABO3 oxides" and the SrTiO3-based ceramic raw material powder were weighed to obtain the "addition ratios" shown in Table 8, and a conductive paste for forming internal electrodes was prepared through the same steps as in the above-mentioned Experimental Example 2-1.

[0175] Here, the content of the ceramic powder in the conductive paste for forming the internal electrode was set to 10% by mass.

[0176] Table 8 shows the "Ionic Radius Ratio (A-site Element / Metal Copper)" as in Table 6. Furthermore, for Sample 57, the ratio of the Sr element's ionic radius (1.18 Å) at a hexacoordinated position, as shown in Table 5, to the copper element's ionic radius (0.77 Å) at a hexacoordinated position is shown.

[0177] 2-3-3. Manufacturing Multilayer Ceramic Capacitors

[0178] A ceramic slurry containing the SrTiO3-based ceramic raw material powder prepared in step 1 was prepared. Next, the ceramic slurry was subjected to a doctor blade method to form ceramic green sheets. Subsequently, a sample multilayer ceramic capacitor was produced through the same steps as in Experimental Example 2-1.

[0179] 2-3-4. Evaluation

[0180] [Table 8]

[0181]

[0182] According to the same procedure as in the case of Experimental Example 2-1, the “coverage ratio” was determined as shown in Table 8, and the evaluation was performed in the same manner.

[0183] 2-3-5. Inspection

[0184] Samples 51 to 56 in Table 8 were rated "O." In these samples 51 to 56, the internal electrodes contained any of CuTiO 3 , CoTiO 3 , and CrTiO 3 as the ABO 3 oxide. Furthermore, the internal electrodes contained copper as the conductive component.

[0185] Here, focusing on ionic radius, as shown in the "CuTiO3" column in Table 5, the ionic radius of copper at a hexacoordinate position is 0.77 Å. Meanwhile, as shown in Table 5, the ionic radius of the hexacoordinate element of CuTiO3, CoTiO3, and CrTiO3, the ABO3 oxides included in the internal electrodes of Samples 51 to 56, at a hexacoordinate position are 0.77 Å, 0.74 Å, and 0.80 Å, respectively.

[0186] In samples 51 to 56 evaluated as "○", the "ionic radius ratio", which is the ratio of the ionic radius of the element at the A site in ABO3 in hexacoordinate to the ionic radius of copper in hexacoordinate, was 0.96 or more and 1.04 or less.

[0187] As shown in this way, regarding CuTiO3, CoTiO3 and CrTiO3 as ABO3 oxides in samples 51 to 56, the ionic radius of the element at the A position in ABO3 at 6 coordination is equal to or close to the ionic radius of copper as a conductive metal that should be included in the internal electrode at 6 coordination. Therefore, the energy difference with the copper in the internal electrode is 0 or small, so it is not discharged from the internal electrode part but remains and plays a role, thereby improving the heat resistance of the internal electrode. As a result, in samples 51 to 56, it can be inferred that the coverage rate exceeds 80%.

[0188] In addition, as in samples 54 to 56, the addition ratio of CuTiO3, CoTiO3 and CrTiO3 does not necessarily have to be 100%. As long as it is above 10%, the effect of improved coverage can be confirmed compared with the case where none of CuTiO3, CoTiO3 and CrTiO3 is included.

[0189] In contrast, in Sample 57, which was evaluated as "×," only SrTiO3, a common material, was added to the internal electrode. In this case, although Sr, as an element at the A site in the perovskite structure ABO3, is 12-coordinated, when solid-dissolved in the A site of the ilmenite structure, it is necessary to compare the ionic radius at the 6-coordinated site, which is the coordination number of the A site in the ilmenite structure. As shown in Table 5, the ionic radius of Sr at the 6-coordinated site is 1.18 Å. Therefore, the ratio of the ionic radius of Sr at the 6-coordinated site to the ionic radius of copper at the 6-coordinated site, i.e., the "ionic radius ratio," is 1.53. As a result, the "ionic radius ratio" deviates from the range of 0.96 to 1.04, and the coverage rate drops to 70%.

[0190] In Sample 57, the "ion radius ratio" deviated from the range of 0.96 to 1.04, SrTiO 3 was partially discharged from the internal electrode, and the heat resistance of the internal electrode was not improved. It is presumed that the coverage was reduced.

[0191] [Experimental Example 3] Conductive metal powder: silver powder

[0192] In Experimental Example 3, silver powder was prepared as the conductive metal powder contained in the conductive paste for forming the internal electrode.

[0193] Meanwhile, AgTiO3, EuTiO3, and NaTiO3 were prepared as ABO3 oxides with specific ionic radii for the ceramic powder contained in the conductive paste for forming the internal electrodes. CuTiO3, SrTiO3, BaTiO3, and CaZrO3 were also prepared as other ABO3 oxides. Table 9 shows the "Crystal Structure," "Coordination Number," "A-site Element," and "Ionic Radius" for these ABO3 oxides. Sr, Ba, and Ca have a 12-coordinated structure in their original perovskite structure. However, when Sr, Ba, and Ca are dissolved in the positions of the 6-coordinated elements (Ag, Eu, and Na) in the ilmenite structure, they also have a 6-coordinated structure. Therefore, the "Ionic Radius" in Table 9 shows the values ​​for the 6-coordinated structure.

[0194] [Table 9]

[0195]

[0196] Hereinafter, Experimental Examples 3-1, 3-2, and 3-3, which were carried out by changing the ceramic raw materials constituting the dielectric layer, will be described.

[0197] (Experimental Example 3-1) Main component of ceramic constituting the dielectric layer: BaTiO3

[0198] 3-1-1. Preparation of BaTiO3-based ceramic raw materials constituting the dielectric layer

[0199] Through the same steps as in Experimental Example 1-1, BaTiO3-based ceramic raw material powder was obtained.

[0200] 3-1-2. Preparation of Conductive Paste for Internal Electrode Formation

[0201] As ceramic powders contained in the conductive paste for forming the internal electrode, powders of "ABO 3 oxides" shown in Table 10 described later and BaTiO 3 -based ceramic raw material powders for the above-mentioned dielectric layers were used.

[0202] The powders of these "ABO3 oxides" and BaTiO3-based ceramic raw material powders were weighed to obtain the "addition ratios" shown in Table 10, and conductive pastes for forming internal electrodes were prepared through the same steps as in the above-mentioned Experimental Example 1-1.

[0203] Here, the content of the ceramic powder in the conductive paste for forming the internal electrode was set to 10% by mass.

[0204] Table 10 shows the ratio of the ionic radius of the A-site element at six coordination levels to the ionic radius of silver to be included in the internal electrode at six coordination levels, i.e., "Ionic Radius Ratio (A-site Element / Metallic Silver)." Furthermore, for Sample 68, the ratio of the Ba element's ionic radius at six coordination levels (1.35 Å) shown in Table 9 to the silver ionic radius at six coordination levels (1.15 Å) is shown.

[0205] 3-1-3. Manufacturing of Multilayer Ceramic Capacitors

[0206] A ceramic slurry containing the BaTiO3-based ceramic raw material powder prepared in step 1 was prepared. Next, the ceramic slurry was subjected to a doctor blade method to form ceramic green sheets. Subsequently, a sample multilayer ceramic capacitor was produced through the same steps as in Experimental Example 1-1.

[0207] 3-1-4. Evaluation

[0208] [Table 10]

[0209]

[0210] According to the same procedure as in the case of Experimental Example 1-1, the “coverage ratio” was determined as shown in Table 6, and the evaluation was performed in the same manner.

[0211] 3-1-5. Inspection

[0212] Samples 61 to 63 and 65 to 67 in Table 10 were rated "O." In these samples 61 to 63 and 65 to 67, the internal electrodes contained any of AgTiO3, EuTiO3, and NaTiO3 as the ABO3 oxide. Furthermore, the internal electrodes contained silver as a conductive component.

[0213] Here, focusing on ionic radius, as shown in the "AgTiO3" section of Table 9, the ionic radius of silver at a hexacoordinate position is 1.15 Å. Meanwhile, as shown in Table 9, the ionic radius of the hexacoordinate position of the elements at the A-site of AgTiO3, EuTiO3, and NaTiO3, the ABO3 oxides included in the internal electrodes of Samples 61 to 63 and 65 to 67, at a hexacoordinate position are 1.15 Å, 1.17 Å, and 1.02 Å, respectively.

[0214] In samples 61 to 63 and 65 to 67 evaluated as "○", the ratio of the ionic radius of the element at the A position in ABO3 at 6 coordination to the ionic radius of silver at 6 coordination, i.e., the "ionic radius ratio" was 0.89 or more and 1.02 or less.

[0215] As such, for the ABO3 oxides AgTiO3, EuTiO3, and NaTiO3 in Samples 61-63 and 65-67, the ionic radius of the element at the A-position in the ABO3 at a six-coordinate position is equal to or similar to the ionic radius of silver, the conductive metal to be contained in the internal electrodes. Therefore, the energy difference with the silver in the internal electrodes is zero or minimal. Therefore, the silver is not expelled from the internal electrodes but remains there, contributing to the improvement of the internal electrode's heat resistance. As a result, it is estimated that the coverage rate in Samples 61-63 and 65-67 increased to 82% or more.

[0216] In addition, as in samples 65 to 67, the addition ratio of AgTiO3, EuTiO3 and NaTiO3 does not necessarily have to be 100%. As long as it is above 10%, the effect of improved coverage can be confirmed compared with the case where none of AgTiO3, EuTiO3 and NaTiO3 is included.

[0217] In contrast, Sample 64, which received an "X" rating, used SrTiO₃ as the ABO₃ oxide. As shown in Table 9, the ionic radius of Sr, the A-site element in ABO₃, at a hexacoordinated position is 1.18 Å. Therefore, the "ionic radius ratio," the ratio of the hexacoordinated ionic radius of Sr to the hexacoordinated ionic radius of silver, was 1.03. This means that the "ionic radius ratio" fell outside the range of 0.89 to 1.02, and the coverage dropped to 76%.

[0218] In addition, in sample 68, which was also evaluated as "×", only BaTiO3, a common material, was added to the internal electrode. In this case, although Ba, as an element at the A site in the ABO3 perovskite structure, is 12-coordinated, when solid-dissolved in the A site of the ilmenite structure, it is necessary to compare the ionic radius at the 6-coordinated position, which is the coordination number of the A site in the ilmenite structure. As shown in Table 9, the ionic radius of Ba at the 6-coordinated position is 1.35Å. Therefore, the ratio of the ionic radius of Ba at the 6-coordinated position to the ionic radius of silver at the 6-coordinated position, that is, the "ionic radius ratio", is 1.17. As a result, the "ionic radius ratio" deviates from the range of 0.89 to 1.02, and the coverage rate drops to 75%.

[0219] In samples 64 and 68, the "ion radius ratio" was outside the range of 0.89 to 1.02, BaTiO 3 was partially discharged from the internal electrode, and the heat resistance of the internal electrode was not improved. It is presumed that the coverage was reduced.

[0220] (Experimental Example 3-2) Main component of ceramic constituting the dielectric layer: CaZrO3

[0221] 3-2-1. Preparation of CaZrO3-based ceramic raw materials constituting the dielectric layer

[0222] Through the same steps as in Experimental Example 1-2, a CaZrO3-based ceramic raw material powder was obtained.

[0223] 3-2-2. Preparation of Conductive Paste for Internal Electrode Formation

[0224] As ceramic powder contained in the conductive paste for forming the internal electrode, powder of "ABO 3 oxide" shown in Table 11 described later and CaZrO 3 -based ceramic raw material powder for the above-mentioned dielectric layer were used.

[0225] The powders of these "ABO3 oxides" and the CaZrO3-based ceramic raw material powder were weighed to obtain the "addition ratios" shown in Table 11, and a conductive paste for forming internal electrodes was prepared through the same steps as in the above-mentioned Experimental Example 3-1.

[0226] Here, the content of the ceramic powder in the conductive paste for forming the internal electrode was set to 10% by mass.

[0227] Table 11 shows the "Ionic Radius Ratio (A-site Element / Metal Silver)" as in Table 10. Furthermore, for Sample 78, the ratio of the Ca element's ionic radius (1.00 Å) at a hexacoordinated position, as shown in Table 9, to the silver element's ionic radius (1.15 Å) at a hexacoordinated position is shown.

[0228] 3-2-3. Manufacturing of Multilayer Ceramic Capacitors

[0229] A ceramic slurry containing the CaZrO3-based ceramic raw material powder prepared in step 1 was prepared. Next, the ceramic slurry was subjected to a doctor blade method to form ceramic green sheets. Subsequently, a sample multilayer ceramic capacitor was produced through the same steps as in Experimental Example 3-1.

[0230] 3-2-4. Evaluation

[0231] [Table 11]

[0232]

[0233] According to the same procedure as in Experimental Example 3-1, the “coverage ratio” was determined as shown in Table 11, and the evaluation was performed in the same manner.

[0234] 3-2-5. Inspection

[0235] Samples 71 to 73 and 75 to 77 in Table 11 were rated "O." In these samples 71 to 73 and 75 to 77, the internal electrodes contained any of AgTiO3, EuTiO3, and NaTiO3 as the ABO3 oxide. Furthermore, the internal electrodes contained silver as a conductive component.

[0236] Here, focusing on ionic radius, as shown in the "AgTiO3" section of Table 9, the ionic radius of silver at the hexacoordinate level is 1.15 Å. Meanwhile, as shown in Table 9, the ionic radius of the hexacoordinated element of AgTiO3, EuTiO3, and NaTiO3, the ABO3 oxides included in the internal electrodes of Samples 71 to 73 and 75 to 77, at the hexacoordinate level are 1.15 Å, 1.17 Å, and 1.02 Å, respectively.

[0237] In samples 71 to 73 and 75 to 77 evaluated as "○", the ratio of the ionic radius of the element at the A position in ABO3 at 6-coordination to the ionic radius of silver at 6-coordination, i.e., the "ionic radius ratio" was 0.89 or more and 1.02 or less.

[0238] As shown in this way, regarding AgTiO3, EuTiO3 and NaTiO3 as ABO3 oxides in samples 71 to 73 and 75 to 77, the ionic radius of the element at the A position in ABO3 at 6 coordination is equal to or close to the ionic radius of silver as a conductive metal to be contained in the internal electrode at 6 coordination. Therefore, the energy difference with the silver in the internal electrode is 0 or small, so it is not discharged from the internal electrode part but remains and plays a role, thereby improving the heat resistance of the internal electrode. As a result, in samples 71 to 73 and 75 to 77, it can be inferred that the coverage is increased to more than 81%.

[0239] In addition, as in samples 75 to 77, the addition ratio of AgTiO3, EuTiO3 and NaTiO3 does not necessarily have to be 100%. As long as it is above 10%, the effect of improved coverage can be confirmed compared with the case where none of AgTiO3, EuTiO3 and NaTiO3 is included.

[0240] In contrast, Sample 74, which received an "X" rating, used CuTiO as the ABO oxide. As shown in Table 9, the ionic radius of Cu, the A-site element in ABO, at a hexacoordinated position is 0.73 Å. Therefore, the ratio of the ionic radius of Cu at a hexacoordinated position to the ionic radius of silver at a hexacoordinated position, or the "ionic radius ratio," was 0.63. In other words, the "ionic radius ratio" fell outside the range of 0.89 to 1.02, and the coverage dropped to 75%.

[0241] In addition, in sample 78, which was also evaluated as "×", only CaZrO3, a common material, was added to the internal electrode. In this case, although Ca, as an element at the A site in the ABO3 perovskite structure, is 12-coordinated, when solid-dissolved in the A site of the ilmenite structure, it is necessary to compare the ionic radius at the 6-coordinated position, which is the coordination number of the A site in the ilmenite structure. As shown in Table 9, the ionic radius of Ca at the 6-coordinated position is 1.00Å. Therefore, the ratio of the ionic radius of Ca at the 6-coordinated position to the ionic radius of silver at the 6-coordinated position, that is, the "ionic radius ratio", is 0.87. Therefore, the "ionic radius ratio" deviates from the range of above 0.89 and below 1.02, and the coverage rate drops to 72%.

[0242] In samples 74 and 78, the "ion radius ratio" was outside the range of 0.89 to 1.02, CaZrO 3 was discharged from the internal electrode portion, and the heat resistance of the internal electrode was not improved. It is presumed that the coverage was reduced.

[0243] (Experimental Example 3-3) Main component of ceramic constituting the dielectric layer: SrTiO3

[0244] 3-3-1. Preparation of SrTiO3-based ceramic raw materials constituting the dielectric layer

[0245] Through the same steps as in Experimental Example 1-3, SrTiO3-based ceramic raw material powder was obtained.

[0246] 3-3-2. Preparation of Conductive Paste for Internal Electrode Formation

[0247] As ceramic powders contained in the conductive paste for forming the internal electrode, powders of "ABO 3 oxides" shown in Table 12 described later and SrTiO 3 -based ceramic raw material powders for the above-mentioned dielectric layers were used.

[0248] The powders of these "ABO3 oxides" and the SrTiO3-based ceramic raw material powder were weighed to obtain the "addition ratios" shown in Table 12, and a conductive paste for forming internal electrodes was prepared through the same steps as in the above-mentioned Experimental Example 3-1.

[0249] Here, the content of the ceramic powder in the conductive paste for forming the internal electrode was set to 10% by mass.

[0250] Table 12 shows the "Ionic Radius Ratio (A-site Element / Metal Silver)" as in Table 10. Furthermore, for Sample 88, the ratio of the Sr element's ionic radius (1.18 Å) at a hexacoordinated position, as shown in Table 9, to the silver element's ionic radius (1.15 Å) at a hexacoordinated position is shown.

[0251] 3-3-3. Manufacturing of Multilayer Ceramic Capacitors

[0252] A ceramic slurry containing the SrTiO3-based ceramic raw material powder prepared in step 1 was prepared. Next, the ceramic slurry was subjected to a doctor blade method to form ceramic green sheets. Subsequently, a sample multilayer ceramic capacitor was produced through the same steps as in Experimental Example 3-1.

[0253] 3-3-4. Evaluation

[0254] [Table 12]

[0255]

[0256] According to the same procedure as in the case of Experimental Example 3-1, the “coverage ratio” was determined as shown in Table 12, and the evaluation was performed in the same manner.

[0257] 3-3-5. Inspection

[0258] Samples 81 to 83 and 85 to 87 in Table 12 were rated "○." In these samples 81 to 83 and 85 to 87, the internal electrodes contained any of AgTiO3, EuTiO3, and NaTiO3 as the ABO3 oxide. Furthermore, the internal electrodes contained silver as a conductive component.

[0259] Here, focusing on ionic radius, as shown in the "AgTiO3" section of Table 9, the ionic radius of silver at the hexacoordinate level is 1.15 Å. Meanwhile, as shown in Table 9, the ionic radius of the hexacoordinated element of AgTiO3, EuTiO3, and NaTiO3, the ABO3 oxides included in the internal electrodes of Samples 81 to 83 and 85 to 87, at the hexacoordinate level are 1.15 Å, 1.17 Å, and 1.02 Å, respectively.

[0260] In samples 81 to 83 and 85 to 87 evaluated as "○", the ratio of the ionic radius of the element at the A position in ABO3 at 6-coordination to the ionic radius of silver at 6-coordination, i.e., the "ionic radius ratio" was 0.89 or more and 1.02 or less.

[0261] As shown in this way, regarding AgTiO3, EuTiO3 and NaTiO3 as ABO3 oxides in samples 81 to 83 and 85 to 87, the ionic radius of the element at the A position in ABO3 at 6 coordination is equal to or close to the ionic radius of silver as a conductive metal to be contained in the internal electrode at 6 coordination. Therefore, the energy difference with the silver in the internal electrode is 0 or small, so it is not discharged from the internal electrode part but remains and plays a role in improving the heat resistance of the internal electrode. As a result, it can be inferred that the coverage rate exceeds 80% in samples 81 to 83 and 85 to 87.

[0262] In addition, as in samples 85 to 87, the addition ratio of AgTiO3, EuTiO3 and NaTiO3 does not necessarily have to be 100%. As long as it is above 10%, the effect of improved coverage can be confirmed compared with the case where none of AgTiO3, EuTiO3 and NaTiO3 is included.

[0263] In contrast, Sample 84, which received an "X" rating, used CuTiO as the ABO oxide. As shown in Table 9, the ionic radius of Cu, the A-site element in ABO, at a hexacoordinated position is 0.73 Å. Therefore, the ratio of the hexacoordinated ionic radius of Cu to the hexacoordinated ionic radius of silver, or the "ionic radius ratio," was 0.63. This means that the "ionic radius ratio" fell outside the range of 0.89 to 1.02, and the coverage dropped to 72%.

[0264] In addition, in sample 88, which was also evaluated as "×", only SrTiO3, a common material, was added to the internal electrode. In this case, although Sr, as an element at the A site in the perovskite structure ABO3, is 12-coordinated, when solid-dissolved in the A site of the ilmenite structure, it is necessary to compare the ionic radius at the 6-coordinated position, which is the coordination number of the A site in the ilmenite structure. As shown in Table 9, the ionic radius of Sr at the 6-coordinated position is 1.18Å. Therefore, the ratio of the ionic radius of Sr at the 6-coordinated position to the ionic radius of silver at the 6-coordinated position, that is, the "ionic radius ratio", is 1.03. As a result, the "ionic radius ratio" deviates from the range of 0.89 to 1.02, and the coverage rate drops to 70%.

[0265] In samples 84 and 88, the "ion radius ratio" was outside the range of 0.89 to 1.02, SrTiO 3 was partially discharged from the internal electrode, and the heat resistance of the internal electrode was not improved. It is presumed that the coverage was reduced.

[0266] [Experimental Example 4] Conductive Metal Powder: Silver-Pd Alloy Powder

[0267] In Experimental Example 4, silver-palladium alloy powder containing 70 atm % of silver and 30 atm % of palladium was prepared as the conductive metal powder contained in the conductive paste for forming the internal electrode.

[0268] On the other hand, as an ABO3 oxide having a specific ionic radius constituting the ceramic powder contained in the conductive paste for forming the internal electrode, (Ag 0.7 , Pd 0.3) TiO3, NaTiO3, and EuTiO3, and BaTiO3, CaZrO3, and SrTiO3 were prepared as other ABO3 oxides. Table 13 shows the "Crystal Structure," "Coordination Number," "A-site Element," and "Ionic Radius" for these ABO3 oxides. Ba, Ca, and Sr have a 12-coordinated structure in their original perovskite structure. However, when Ba, Ca, and Sr are dissolved in the positions of the 6-coordinated elements (Ag-Pd, Na, and Eu) in the ilmenite structure, they also have a 6-coordinated structure. Therefore, the "Ionic Radius" in Table 13 shows the value for the 6-coordinated structure.

[0269] [Table 13]

[0270]

[0271] Hereinafter, Experimental Examples 4-1, 4-2, and 4-3, which were carried out by changing the ceramic raw materials constituting the dielectric layer, will be described.

[0272] (Experimental Example 4-1) Main component of ceramic constituting the dielectric layer: BaTiO3

[0273] 4-1-1. Preparation of BaTiO3-based ceramic raw materials constituting the dielectric layer

[0274] Through the same steps as in Experimental Example 1-1, BaTiO3-based ceramic raw material powder was obtained.

[0275] 4-1-2. Preparation of Conductive Paste for Internal Electrode Formation

[0276] As ceramic powders contained in the conductive paste for forming the internal electrode, powders of "ABO 3 oxides" shown in Table 14 described later and BaTiO 3 -based ceramic raw material powders for the above-mentioned dielectric layers were used.

[0277] The powders of these "ABO3 oxides" and the BaTiO3-based ceramic raw material powder were weighed to obtain the "addition ratios" shown in Table 14, and a conductive paste for forming internal electrodes was prepared through the same steps as in the above-mentioned Experimental Example 1-1.

[0278] Here, the content of the ceramic powder in the conductive paste for forming the internal electrode was set to 10% by mass.

[0279] Table 14 shows the ratio of the ionic radius of the A-site element at 6 coordination to the ionic radius of the silver-palladium alloy to be included in the internal electrode, that is, the "ionic radius ratio (A-site element / Ag 0.7 Pd 0.3alloy)". In addition, for Sample 97, the ratio of the ionic radius of the Ba element at 6 coordination (1.35 Å) shown in Table 13 to the ionic radius of the silver-palladium alloy at 6 coordination (1.06 Å) is shown.

[0280] 4-1-3. Manufacturing of Multilayer Ceramic Capacitors

[0281] A ceramic slurry containing the BaTiO3-based ceramic raw material powder prepared in step 1 was prepared. Next, the ceramic slurry was subjected to a doctor blade method to form ceramic green sheets. Subsequently, a sample multilayer ceramic capacitor was produced through the same steps as in Experimental Example 1-1.

[0282] 4-1-4. Evaluation

[0283] [Table 14]

[0284]

[0285] According to the same procedure as in the case of Experimental Example 1-1, the “coverage ratio” was determined as shown in Table 6, and the evaluation was performed in the same manner.

[0286] 4-1-5. Inspection

[0287] The "Evaluation" of samples 91 to 96 in Table 14 is "○". In these samples 91 to 96, the internal electrodes contain (Ag 0.7 , Pd 0.3 ) TiO 3 , NaTiO 3 , and EuTiO 3 as the ABO 3 oxide. In addition, the internal electrode contains a silver-palladium alloy as a conductive component.

[0288] Here, if we focus on the ionic radius, first, as shown in the "(Ag, Pd)TiO3" item in Table 13, the ionic radius of the silver-palladium alloy at 6 coordination is 1.06 Å. On the other hand, as shown in Table 13, the ABO3 oxide contained in the internal electrodes of samples 91 to 96, (Ag, Pd)TiO3, 0.7 , Pd 0.3 ) The ionic radius of the element at the A position of TiO3, NaTiO3 and EuTiO3 under 6-coordination is 1.06Å, 1.02Å and 1.17Å respectively.

[0289] In samples 91 to 96 evaluated as "○", the "ionic radius ratio", which is the ratio of the ionic radius of the element at the A site in ABO3 in hexacoordinates to the ionic radius of the metal element contained in the conductive metal particles in hexacoordinates, is 0.96 or more and 1.10 or less.

[0290] As such, regarding the ABO3 oxides (Ag 0.7 , Pd0.3 ) TiO₃, NaTiO₃, and EuTiO₃. The ionic radius of the A-position element in ABO₃ at a six-coordinate position is equal to or similar to the ionic radius of the silver-palladium alloy, the conductive metal to be included in the internal electrodes. Therefore, the energy difference with the silver-palladium alloy in the internal electrodes is zero or minimal. Therefore, the element is not expelled from the internal electrodes but remains there, contributing to the improvement of the internal electrode's heat resistance. As a result, it is estimated that the coverage rate increased to 82% or more in Samples 91 to 96.

[0291] In addition, as in samples 94 to 96, (Ag 0.7 , Pd 0.3 ) The addition ratio of TiO3, NaTiO3 and EuTiO3 does not have to be 100%, as long as it is 10% or more, it is the same as that of the alloy without (Ag 0.7 , Pd 0.3 ) Compared with the case of any one of TiO3, NaTiO3 and EuTiO3, the effect of improving the coverage can be confirmed.

[0292] In contrast, in Sample 97, which was evaluated as "×," only BaTiO3, a common material, was added to the internal electrode. In this case, although Ba, as an element at the A site in the ABO3 perovskite structure, is 12-coordinated, when solid-dissolved in the A site of the ilmenite structure, it is necessary to compare the ionic radius at the 6-coordinated position, which is the coordination number of the A site in the ilmenite structure. As shown in Table 13, the ionic radius of Ba at the 6-coordinated position is 1.35 Å. Therefore, the ratio of the ionic radius of Ba at the 6-coordinated position to the ionic radius of the silver-palladium alloy at the 6-coordinated position, i.e., the "ionic radius ratio," is 1.27. As a result, the "ionic radius ratio" deviates from the range of 0.96 to 1.10, and the coverage rate drops to 75%.

[0293] In Sample 97, the "ion radius ratio" was outside the range of 0.96 to 1.10, BaTiO 3 was partially discharged from the internal electrode, and the heat resistance of the internal electrode was not improved. It is presumed that the coverage was reduced.

[0294] (Experimental Example 4-2) Main component of ceramic constituting the dielectric layer: CaZrO3

[0295] 4-2-1. Preparation of CaZrO3-based ceramic raw materials constituting the dielectric layer

[0296] Through the same steps as in Experimental Example 1-2, a CaZrO3-based ceramic raw material powder was obtained.

[0297] 4-2-2. Preparation of Conductive Paste for Internal Electrode Formation

[0298] As ceramic powders contained in the conductive paste for forming the internal electrode, powders of "ABO 3 oxides" shown in Table 15 described later and CaZrO 3 -based ceramic raw material powders for the above-mentioned dielectric layers were used.

[0299] The powders of these "ABO3 oxides" and the CaZrO3-based ceramic raw material powder were weighed to obtain the "addition ratios" shown in Table 15, and a conductive paste for forming internal electrodes was prepared through the same steps as in the above-mentioned Experimental Example 4-1.

[0300] Here, the content of the ceramic powder in the conductive paste for forming the internal electrode was set to 10% by mass.

[0301] In Table 15, similarly to the case of Table 14, the "ion radius ratio (A-site element / Ag 0.7 Pd 0.3 alloy)". In addition, for sample 107, the ratio of the ionic radius of the Ca element at 6 coordination (1.00 Å) shown in Table 13 to the ionic radius of the silver-palladium alloy at 6 coordination (1.06 Å) is shown.

[0302] 4-2-3. Manufacturing of Multilayer Ceramic Capacitors

[0303] A ceramic slurry containing the CaZrO3-based ceramic raw material powder prepared in step 1 was prepared. Next, the ceramic slurry was subjected to a doctor blade method to form ceramic green sheets. Subsequently, a sample multilayer ceramic capacitor was produced through the same steps as in Experimental Example 4-1.

[0304] 4-2-4. Evaluation

[0305] [Table 15]

[0306]

[0307] According to the same procedure as in the case of Experimental Example 4-1, the “coverage ratio” was determined as shown in Table 15, and the evaluation was performed in the same manner.

[0308] 4-2-5. Inspection

[0309] The "Evaluation" of samples 101 to 106 in Table 15 is "○". In these samples 101 to 106, the internal electrodes contain (Ag 0.7 , Pd 0.3 ) TiO 3 , NaTiO 3 , and EuTiO 3 as the ABO 3 oxide. In addition, the internal electrode contains a silver-palladium alloy as a conductive component.

[0310] Here, if we focus on the ionic radius, first, as shown in the "(Ag, Pd)TiO3" item in Table 13, the ionic radius of the silver-palladium alloy at 6 coordination is 1.06 Å. On the other hand, as shown in Table 13, the ABO3 oxide contained in the internal electrodes of samples 101 to 106, (Ag, Pd)TiO3, 0.7 , Pd 0.3 ) The ionic radius of the element at the A position of TiO3, NaTiO3 and EuTiO3 under 6-coordination is 1.06Å, 1.02Å and 1.17Å respectively.

[0311] In samples 101 to 106 evaluated as "○", the "ionic radius ratio", which is the ratio of the ionic radius of the element at the A site in ABO3 in hexacoordinate to the ionic radius of the metal element contained in the conductive metal particles in hexacoordinate, is 0.96 or more and 1.10 or less.

[0312] As such, regarding the ABO3 oxides (Ag 0.7 , Pd 0.3 ) TiO3, NaTiO3 and EuTiO3, the ionic radius of the element at the A position in ABO3 at 6 coordination is equal to or close to the ionic radius of the silver-palladium alloy at 6 coordination as a conductive metal to be contained in the internal electrode. Therefore, the energy difference with the silver-palladium alloy in the internal electrode is 0 or small, so it is not discharged from the internal electrode part but remains and plays a role, thereby improving the heat resistance of the internal electrode. As a result, in samples 101 to 106, it can be inferred that the coverage is increased to more than 81%.

[0313] In addition, as in samples 104 to 106, (Ag 0.7 , Pd 0.3 ) The addition ratio of TiO3, NaTiO3 and EuTiO3 does not have to be 100%, as long as it is 10% or more, it is the same as that of the alloy without (Ag 0.7 , Pd 0.3 ) Compared with the case of any one of TiO3, NaTiO3 and EuTiO3, the effect of improving the coverage can be confirmed.

[0314] In contrast, in sample 107, which was evaluated as "×," only CaZrO3, a common material, was added to the internal electrode. In this case, although Ca, as an element at the A site in the ABO3 perovskite structure, is 12-coordinated, when solid-dissolved in the A site of the ilmenite structure, it is necessary to compare the ionic radius at the 6-coordinated position, which is the coordination number of the A site in the ilmenite structure. As shown in Table 13, the ionic radius of Ca at the 6-coordinated position is 1.00 Å. Therefore, the ratio of the ionic radius of Ca at the 6-coordinated position to the ionic radius of the silver-palladium alloy at the 6-coordinated position, i.e., the "ionic radius ratio," is 0.94. As a result, the "ionic radius ratio" deviates from the range of 0.96 to 1.10, and the coverage rate drops to 72%.

[0315] In sample 107, the "ion radius ratio" deviated from the range of 0.96 to 1.10, CaZrO 3 was discharged from the internal electrode portion, and the heat resistance of the internal electrode was not improved. It is presumed that the coverage was reduced.

[0316] (Experimental Example 4-3) Main component of ceramic constituting the dielectric layer: SrTiO3

[0317] 4-3-1. Preparation of SrTiO3-based ceramic raw materials constituting the dielectric layer

[0318] Through the same steps as in Experimental Example 1-3, SrTiO3-based ceramic raw material powder was obtained.

[0319] 4-3-2. Preparation of Conductive Paste for Internal Electrode Formation

[0320] As ceramic powders contained in the conductive paste for forming the internal electrode, powders of "ABO 3 oxides" shown in Table 16 described later and SrTiO 3 -based ceramic raw material powders for the above-mentioned dielectric layers were used.

[0321] The powders of these "ABO3 oxides" and the SrTiO3-based ceramic raw material powder were weighed to obtain the "addition ratios" shown in Table 16, and a conductive paste for forming internal electrodes was prepared through the same steps as in the above-mentioned Experimental Example 4-1.

[0322] Here, the content of the ceramic powder in the conductive paste for forming the internal electrode was set to 10% by mass.

[0323] In Table 16, similarly to Table 14, the “ion radius ratio (A-site element / Ag 0.7 Pd 0.3 alloy)". In addition, for Sample 117, the ratio of the ionic radius of the Sr element at 6 coordination (1.18 Å) shown in Table 13 to the ionic radius of the silver-palladium alloy at 6 coordination (1.06 Å) is shown.

[0324] 4-3-3. Manufacturing of Multilayer Ceramic Capacitors

[0325] A ceramic slurry containing the SrTiO3-based ceramic raw material powder prepared in step 1 was prepared. Next, the ceramic slurry was subjected to a doctor blade method to form ceramic green sheets. Subsequently, a sample multilayer ceramic capacitor was produced through the same steps as in Experimental Example 4-1.

[0326] 4-3-4. Evaluation

[0327] [Table 16]

[0328]

[0329] According to the same procedure as in the case of Experimental Example 4-1, the “coverage ratio” was determined as shown in Table 16, and the evaluation was performed in the same manner.

[0330] 4-3-5. Inspection

[0331] The "Evaluation" of samples 111 to 116 in Table 16 is "○". In these samples 111 to 116, the internal electrodes contain (Ag 0.7 , Pd 0.3 ) TiO 3 , NaTiO 3 , and EuTiO 3 as the ABO 3 oxide. In addition, the internal electrode contains a silver-palladium alloy as a conductive component.

[0332] Here, if we focus on the ionic radius, first, as shown in the "(Ag, Pd)TiO3" item in Table 13, the ionic radius of the silver-palladium alloy at 6 coordination is 1.06 Å. On the other hand, as shown in Table 13, the ABO3 oxide contained in the internal electrodes of samples 111 to 116, (Ag, Pd)TiO3, 0.7 , Pd 0.3 ) The ionic radius of the element at the A position of TiO3, NaTiO3 and EuTiO3 under 6-coordination is 1.06Å, 1.02Å and 1.17Å respectively.

[0333] In samples 111 to 116 evaluated as "○", the ratio of the ionic radius of the element at the A-site in ABO3 at 6 coordination to the ionic radius of the silver-palladium alloy at 6 coordination, i.e., the "ionic radius ratio" was 0.96 or more and 1.10 or less.

[0334] As such, regarding the ABO3 oxides (Ag 0.7 , Pd 0.3) TiO3, NaTiO3 and EuTiO3, the ionic radius of the element at the A position in ABO3 at 6 coordination is equal to or close to the ionic radius of the silver-palladium alloy at 6 coordination as a conductive metal to be contained in the internal electrode. Therefore, the energy difference with the silver-palladium alloy in the internal electrode is 0 or small, so it is not discharged from the internal electrode part but remains and plays a role, thereby improving the heat resistance of the internal electrode. As a result, in samples 111 to 116, it can be inferred that the coverage exceeds 80%.

[0335] In addition, as in samples 114 to 116, (Ag 0.7 , Pd 0.3 ) The addition ratio of TiO3, NaTiO3 and EuTiO3 does not have to be 100%, as long as it is 10% or more, it is the same as that of the alloy without (Ag 0.7 , Pd 0.3 ) Compared with the case of any one of TiO3, NaTiO3 and EuTiO3, the effect of improving the coverage can be confirmed.

[0336] In contrast, in Sample 117, which was evaluated as "×," only SrTiO3, a common material, was added to the internal electrode. In this case, although Sr, as an element at the A site in the perovskite structure ABO3, is 12-coordinated, when solid-dissolved in the A site of the ilmenite structure, it is necessary to compare the ionic radius at the 6-coordinated position, which is the coordination number of the A site in the ilmenite structure. As shown in Table 13, the ionic radius of Sr at the 6-coordinated position is 1.18 Å. Therefore, the ratio of the ionic radius of Sr at the 6-coordinated position to the ionic radius of the silver-palladium alloy at the 6-coordinated position, i.e., the "ionic radius ratio," is 1.11. As a result, the "ionic radius ratio" deviates from the range of 0.96 to 1.10, and the coverage rate drops to 70%.

[0337] In Sample 117, the "ion radius ratio" was outside the range of 0.96 to 1.10, SrTiO 3 was partially discharged from the internal electrode, and the heat resistance of the internal electrode was not improved. It is presumed that the coverage was reduced.

[0338] [Summarize]

[0339] From the results of Experimental Examples 1 to 4 described above, the following preferred range was found for the ratio of the ionic radius of the element at the A site in ABO 3 in hexacoordinates to the ionic radius of the metal contained in the conductive metal powder in hexacoordinates.

[0340] (1) Experimental Example 1: 0.97-1.04

[0341] (2) Experimental Example 2: 0.96~1.04

[0342] (3) Experimental Example 3: 0.89~1.02

[0343] (4) Experimental Example 4: 0.96~1.10

[0344] The types of metals constituting the conductive metal powder varied as follows: nickel in Experimental Example 1, copper in Experimental Example 2, silver in Experimental Example 3, and a silver-palladium alloy in Experimental Example 4. However, even with these different metal types, there was a common range for the appropriate ionic radius ratio. This common range is defined as the scope of the present invention. Specifically, the present invention is characterized in that the ratio of the ionic radius of the element at the A-position of the ABO3 structure at six coordinations to the ionic radius of the metal contained in the conductive metal powder at six coordinations is 0.97 or greater and 1.02 or less.

[0345] In the experimental examples described above, nickel powder, copper powder, silver powder, and silver-palladium alloy powder were used as the conductive metal powder contained in the conductive paste for forming the internal electrodes. However, conductive metal powders other than the above powders can also be used as the conductive metal powder. Furthermore, regarding the ABO3-type oxides of a specific ionic radius, any ABO3-type oxide may be used as long as the ratio of the ionic radius of the element at the A position in ABO3 at 6 coordination to the ionic radius of the metal element contained in the conductive metal powder of the conductive paste at 6 coordination is 0.97 or more and 1.02 or less.

[0346] The present invention may be implemented as follows.

[0347] <1>

[0348] A conductive paste for forming internal electrodes of a multilayer ceramic capacitor, comprising conductive metal powder, ceramic powder, an organic solvent, and an organic binder, wherein:

[0349] At least a portion of the ceramic powder is a powder of an ABO3 type oxide having a specific ionic radius, and the ratio of the ionic radius of the element at the A position in ABO3 at 6 coordination to the ionic radius of the metal contained in the conductive metal powder at 6 coordination is greater than 0.97 and less than 1.02.

[0350] <2>

[0351] The conductive paste according to <1>, wherein

[0352] The ABO3 type oxide having the specific ionic radius has an ilmenite crystal structure.

[0353] <3>

[0354] The conductive paste according to <1> or <2>, wherein

[0355] The conductive metal powder includes one selected from nickel, copper, silver, and a silver-palladium alloy.

[0356] <4>

[0357] The conductive paste according to any one of <1> to <3>, wherein

[0358] More than 10% by volume of the ceramic powder is powder containing an ABO3 type oxide having the specific ionic radius, and the remainder of the ceramic powder is powder containing at least one selected from BaTiO3, SrTiO3, and CaZrO3 as a main component.

[0359] <5>

[0360] A multilayer ceramic capacitor comprising:

[0361] A laminated body comprising a plurality of laminated dielectric layers made of ceramic and a plurality of internal electrodes arranged along a plurality of interfaces between the dielectric layers.

[0362] The internal electrode includes a conductive component and a ceramic component, at least a portion of the ceramic component includes an ABO3 type oxide with a specific ionic radius, and the ratio of the ionic radius of the element at the A position in ABO3 at a 6-coordinate position to the ionic radius of the metal included in the conductive component at a 6-coordinate position is greater than 0.97 and less than 1.02.

[0363] Description of Reference Numerals

[0364] 1: Multilayer ceramic capacitor;

[0365] 2: laminate;

[0366] 3: dielectric layer;

[0367] 4, 5: internal electrodes;

[0368] 6, 7: External electrodes.

Claims

1. A conductive paste for forming internal electrodes of a multilayer ceramic capacitor, comprising conductive metal powder, ceramic powder, an organic solvent, and an organic binder, wherein: At least a portion of the ceramic powder is a powder of an ABO3 type oxide having a specific ionic radius, and the ratio of the ionic radius of the element at the A position in ABO3 at 6 coordination to the ionic radius of the metal contained in the conductive metal powder at 6 coordination is greater than 0.97 and less than 1.

02.

2. The conductive paste according to claim 1, wherein The ABO3 type oxide having the specific ionic radius has an ilmenite crystal structure.

3. The conductive paste according to claim 1 or 2, wherein The conductive metal powder includes one selected from nickel, copper, silver, and a silver-palladium alloy.

4. The conductive paste according to any one of claims 1 to 3, wherein More than 10% by volume of the ceramic powder is powder containing an ABO3 type oxide having the specific ionic radius, and the remainder of the ceramic powder is powder containing at least one selected from BaTiO3, SrTiO3, and CaZrO3 as a main component.

5. A multilayer ceramic capacitor comprising: A laminated body comprising a plurality of laminated dielectric layers made of ceramic and a plurality of internal electrodes arranged along a plurality of interfaces between the dielectric layers. The internal electrode includes a conductive component and a ceramic component, at least a portion of the ceramic component includes an ABO3 type oxide with a specific ionic radius, and the ratio of the ionic radius of the element at the A position in ABO3 at a 6-coordinate position to the ionic radius of the metal included in the conductive component at a 6-coordinate position is greater than 0.97 and less than 1.02.

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