Dielectric ceramic composition, method for producing same, and multilayer ceramic capacitor

Abstract

A dielectric ceramic composition according to the present disclosure comprises barium titanate as a main component, contains, in a solid solution in the barium titanate, at least one metal element selected from the group consisting of Cu and Fe in an amount of 0.5 moles or more per 100 moles of titanium constituting the barium titanate, and contains an auxiliary component comprising at least one element selected from the group consisting of Mg, Mn, Cr, Zn, Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb.

Description

Dielectric ceramic composition, method for manufacturing dielectric ceramic composition, and multilayer ceramic capacitor

[0001] The present disclosure relates to a dielectric ceramic composition, a method for manufacturing a dielectric ceramic composition, and a multilayer ceramic capacitor.

[0002] High dielectric constant ceramic capacitors have characteristics such that the capacitance decreases when a direct current is applied (hereinafter referred to as DC bias characteristics), and the capacitance decreases over time when a direct current is applied (hereinafter referred to as DC aging characteristics).

[0003] Regarding techniques for improving DC bias characteristics, a technique of solid-solubilizing Cu in BaTiO ｄｅｆｅｃｔ , ｏ (barium titanate), which is a ferroelectric, has been disclosed (Non-Patent Document 1). Non-Patent Document 1 discloses that in barium titanate in which Cu is solid-solubilized, a defect dipole (D ｏ ) composed of Cu and oxygen vacancies (V ｄｅｆｅｃｔ ) is formed, and very high dielectric performance can be obtained by the interaction with the spontaneous polarization of barium titanate.

[0004] Matsuo et al., “Utilizing ferrorestorable polarization in energy-storage ceramic capacitors”, [online], Published: 07 October 2022, NPG Asia Materials (2022) 14:80 <URL:https: / / doi.org / 10.1038 / s41427-022-00426-z>

[0005] The present disclosure provides the following means.

[0006] <Dielectric ceramic composition> [1] A dielectric ceramic composition containing barium titanate as a main component, at least one metal element selected from the group consisting of Cu and Fe, dissolved in 0.5 mol or more of titanium in 100 mol of titanium constituting the barium titanate, and containing a sub-component containing at least one selected from the group consisting of Mg, Mn, Cr, Zn, Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb. [2] A dielectric ceramic composition containing barium titanate as a main component, Mn dissolved in 0.5 mol or more of titanium in 100 mol of titanium constituting the barium titanate, and containing a sub-component containing at least one selected from the group consisting of Mg, Cr, Zn, Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb.

[0007] <Multilayer ceramic capacitor>[3] A multilayer ceramic capacitor having a capacitor body in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated, and an external electrode provided on an end face where the plurality of internal electrode layers of the capacitor body are exposed, wherein the plurality of dielectric layers contain the dielectric ceramic composition according to [1] or [2].

[0008] <Method for manufacturing dielectric ceramic composition>[4] A method for manufacturing a dielectric ceramic composition, comprising: mixing a raw material of barium titanate and a solid solution component containing at least one metal element selected from the group consisting of Cu, Fe, and Mn at 0.5 mol or more per 100 mol of titanium (Ti) to obtain a mixture; adding a sub-component containing at least one selected from the group consisting of Mg, Mn, Cr, Zn, Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb to the mixture; and firing the mixture to which the sub-component has been added.

[0009] Cu is dissolved in barium titanate to form defect dipoles (D ｄｅｆｅｃｔThis graph shows the results of verifying the dielectric performance of barium titanate in which a ) was formed. This figure shows the results of measuring the DC aging characteristics using a total of four samples: standard sample 1 in which 1.5 mol% Cu was solid-dissolved in barium titanate, a sample in which Dy was added as a minor component to standard sample 1, a sample in which W was added as a minor component to standard sample 1, and a sample in which Mg was added as a minor component to standard sample 1. The horizontal axis represents the DC bias application time (h), and the vertical axis represents the rate of change of DC aging. This figure shows the DC bias characteristics of standard sample 2 in which 1.5 mol% Cu was solid-dissolved in barium titanate, a sample in which 0.3 mol% of the donor element W was added as a minor component to standard sample 2, and a sample in which 0.5 mol% of the acceptor element Mg was added as a minor component to standard sample 2. The horizontal axis represents the DC bias (V / μm), and the vertical axis represents the relative permittivity (εr). This figure shows the results of measuring DC aging characteristics using a total of four samples: a standard sample 2 in which 1.5 mol% Cu was solid-dissolved in barium titanate; a sample in which 0.5 mol% Dy was added as a minor component to standard sample 2; a sample in which 0.5 mol% Mg was added as a minor component to standard sample 2; and a sample in which 0.2 mol% Dy and 1.0% Mg were added as minor components to standard sample 2. The horizontal axis represents time (h), and the vertical axis represents the rate of change of DC aging. This figure shows the results of measuring DC bias characteristics using a total of three samples: a sample in which 0.05 mol% Dy was added to standard sample 3, which was solid-dissolved in barium titanate with 1.5 mol% Cu and 1.0 mol% Mg; a sample in which 0.1 mol% Dy was added to standard sample 3; and a sample in which 0.2 mol% Dy was added to standard sample 3. The horizontal axis represents DC bias (V / μm), and the vertical axis represents relative permittivity (εr). This figure shows the results of measuring the DC aging characteristics using a total of three samples: a sample in which 0.05 mol% of Dy was added to the reference sample 3, a sample in which 0.1 mol% of Dy was added to the reference sample 3, and a sample in which 0.2 mol% of Dy was added to the reference sample 3. The horizontal axis represents time (h), and the vertical axis represents the rate of change of DC aging.This figure shows the results of measuring DC aging characteristics using a total of six samples: a standard sample 4 in which 1.2 mol% Cu was dissolved in barium titanate; a sample in which Mg and Gd were added to the standard sample 4; a sample in which Mg and Dy were added to the standard sample 4; a sample in which Mg and Ho were added to the standard sample 4; a sample in which Mg and Y were added to the standard sample 4; and a sample in which Mg and Yb were added to the standard sample 4. The horizontal axis represents time (h), and the vertical axis represents the rate of change of DC aging. This figure shows the results of measuring DC aging characteristics using a total of six samples: three samples without any added minor components and three samples in which 1.0 mol% Mg and 0.2 mol% Dy were added as minor components to each of the following: a standard sample 5 in which 1.2 mol% Cu was dissolved in barium titanate; a standard sample 6 in which 1.2 mol% Mn was dissolved in barium titanate; and a standard sample 7 in which Fe was dissolved in barium titanate. The horizontal axis represents time (h), and the vertical axis represents the rate of change during DC aging.

[0010] The inventors have developed a method for solid-solving Cu to create a defect dipole (D ｄｅｆｅｃｔ The dielectric properties of the barium titanate in which the defect dipole (D) is formed were verified, and the defect dipole (D) was verified. ｄｅｆｅｃｔ In barium titanate where a defect dipole (D) is formed, we found that the DC bias characteristics improved, while the DC aging characteristics deteriorated. Specifically, as shown in Figure 1, when Cu is dissolved to form a defect dipole (D) ｄｅｆｅｃｔ We found that when a DC voltage (3V / μm) that maximizes the dielectric constant is continuously applied to barium titanate in which a ) has been formed, under the conditions of a temperature of 25°C, a frequency of 100Hz, and an AC voltage of 0.26V / μm, the dielectric constant decreases over time, and the rate of change after 48 hours is approximately -50%. This disclosure is based on this finding, and according to this disclosure, it is possible to provide a dielectric ceramic composition and a multilayer ceramic capacitor that can improve both DC bias characteristics and DC aging characteristics.

[0011] The present disclosure will be described in detail below with reference to one embodiment.

[0012] In this specification, the notation "XX to YY" means "XX or more and YY or less." Furthermore, in this specification, the lower and upper limits of numerical ranges (for example, ranges of content, etc.) described in stages can be combined independently of each other.

[0013] [Dielectric ceramic composition] The dielectric ceramic composition of this disclosure may be used, for example, in the manufacture of multilayer ceramic capacitors.

[0014] In one embodiment, the dielectric ceramic composition mainly comprises barium titanate, and contains at least one metallic element selected from the group consisting of Cu and Fe, in a solid solution with the barium titanate at a concentration of 0.5 moles or more per 100 moles of titanium constituting the barium titanate, and contains a minor component comprising at least one selected from the group consisting of Mg, Mn, Cr, Zn, Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb.

[0015] In other embodiments, the dielectric ceramic composition mainly comprises barium titanate, with Mn dissolved in the barium titanate at a concentration of 0.5 moles or more per 100 moles of titanium constituting the barium titanate, and contains a minor component comprising at least one selected from the group consisting of Mg, Cr, Zn, Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb.

[0016] (Main component) In this disclosure, the main component refers to the component whose main peak is observed by XRD analysis in a dielectric ceramic composition, for example. Specifically, the main component of this disclosure is barium titanate (BaTiO2). ３ Barium titanate has a perovskite-type crystal structure, where the site where barium (Ba) is located is called the A site, and the site where titanium (Ti) is located is called the B site.

[0017] (Solid solution component) In the present disclosure, "solid solution" refers to a state in which a metal element penetrates into the crystal structure of barium titanate. In the present disclosure, the solid solution component is a component containing a metal element that is solid dissolved in barium titanate. The solid solution component may be an oxide containing the metal element or a carbonate.

[0018] In one embodiment, at least one metal element selected from the group consisting of Cu and Fe is solid dissolved in barium titanate as the main component. The metal element is Cu ３＋ , Fe ３＋ and Fe ２＋ may be solid dissolved and contained in the barium titanate as metal ions containing at least one selected from the group consisting of. The metal element is Cu ３＋ and Cu ２＋ may be solid dissolved and contained in the barium titanate as metal ions containing.

[0019] In another embodiment, Mn is solid dissolved in barium titanate as the main component. The Mn may be at least one metal ion selected from the group consisting of Mn ３＋ and Mn ２＋ .

[0020] The method of solid dissolving the metal element in barium titanate is not particularly limited, but it may be prepared by a solid phase reaction of a mixture in which raw material powders are mixed.

[0021] When a metal element is solid dissolved in barium titanate, a defective dipole (D ｄｅｆｅｃｔ ) is formed. For example, when at least one metal ion selected from the group consisting of Cu ３＋ , Fe ３＋ , Fe ２＋ , Mn ３＋ and Mn ２＋ is solid dissolved, the metal ion replaces Ti ４＋ located at the B site of barium titanate and associates with an oxygen vacancy (V ｏ ) to form a defective dipole (D ｄｅｆｅｃｔ ).

[0022] At this time, the Ti ４＋The defect dipole (D) formed depends on the valence of the metal ion that replaces it. ｄｅｆｅｃｔ The polarization direction in which the ) is stabilized is different. For example, Cu ２＋ Defect dipole (D) formed by ｄｅｆｅｃｔ There are multiple polarization directions in which Cu is most stable, ３＋ Defect dipole (D) formed by ｄｅｆｅｃｔ The polarization direction in which the domain is most stable is limited to the same direction as the spontaneous polarization direction of the domain. ３＋ Fe ２＋ Mn ３＋ and Mn ２＋ Similarly, in the case of a defect dipole (D), if the polarization direction is the same as the spontaneous polarization direction of the domain, ｄｅｆｅｃｔ ) becomes the most stable. Therefore, the defect dipole (D) formed by the solid solution of metal ions is the most stable. ｄｅｆｅｃｔ When the polarization direction of the domain and the spontaneous polarization direction of the domain are aligned, the internal electric field (E ｉ Because the domain walls act to cancel out the externally applied electric field, they become less likely to move and are stabilized. This improves the DC bias characteristics. Here, "domain walls" refer to the boundaries between domains with different polarization directions.

[0023] Furthermore, the presence of metal elements in solid solution in barium titanate can be confirmed by local elemental analysis using energy-dispersive X-ray spectroscopy (TEM-EDS), etc. The amount of solid-solution metal elements can be determined by ICP emission spectroscopy, and using a calibration curve based on a standard sample for comparison, it can be calculated as the molar ratio of a specific element to the main component of the dielectric ceramic composition.

[0024] More defective dipoles (D ｄｅｆｅｃｔ The formation of a defective dipole (D) is advantageous for improving DC bias characteristics. ｄｅｆｅｃｔ To promote the formation of a defect dipole (D), the amount of metal element in the solid solution may be 0.5 moles or more per 100 moles of titanium (Ti) constituting the barium titanate. With such a configuration, a defect dipole (D) is formed. ｄｅｆｅｃｔThe formation of a defect dipole (D) is promoted, improving the DC bias characteristics. The amount of metal element in solid solution is not limited to this, and may be 1.0 mole or more, or 1.5 mole or more, per 100 moles of titanium (Ti) constituting the barium titanate. When the amount of metal element in solid solution to barium titanate increases, the formation of a defect dipole (D) is promoted, improving the DC bias characteristics. ｄｅｆｅｃｔ The formation of a defect dipole (D) is further promoted, thus improving the DC bias characteristics. The amount of metal element in solid solution may be 2.0 moles or less per 100 moles of titanium (Ti) constituting the barium titanate. The upper limit for metal elements that solid-solve in barium titanate is considered to be about 2.0 moles per 100 moles of titanium (Ti) constituting the barium titanate, and even if the metal element does not solid-solve and exists as a separate phase in the dielectric ceramic, defect dipoles (D) are formed. ｄｅｆｅｃｔ ) is not formed.

[0025] The valence of the metal element in the solid solution can be determined, for example, by checking the color of the prepared dielectric ceramic composition. For example, Cu in the solid solution ３＋ When a large amount is present, the dielectric composition becomes black or reddish-brown, Cu ２＋ When a large amount is present, the dielectric composition will be yellow or orange, Cu ＋ If it contains a large amount of Fe, it will turn black. ３＋ When it contains a large amount of Fe, the dielectric composition will be black or reddish-brown. ２＋ When a large amount of Mn is present, the dielectric composition will turn yellow. ３＋ When a large amount is present, the dielectric composition will be black or brown, Mn ２＋ When a large amount of this substance is present, the dielectric composition will be dark red.

[0026] (Minor Components) In this disclosure, minor components refer to components contained in the dielectric ceramic composition in amounts less than the main components. The presence of minor components can be identified by ICP emission spectroscopy. Furthermore, the content of identified elements can be determined as the molar ratio of the specific element to the main components of the dielectric ceramic composition, using a calibration curve based on a comparative standard sample.

[0027] The addition of minor components increases lattice defects within the barium titanate crystal lattice. Domain walls are stabilized on these lattice defects, thus reducing the energy required for domain wall formation. As a result, domain wall movement is hindered, ensuring a sufficient number of domains capable of polarization reversal. This improves the DC aging characteristics.

[0028] In one embodiment, when at least one metal element selected from the group consisting of Cu and Fe is in solid solution in the main component, barium titanate, the minor component is at least one selected from the group consisting of Mg, Mn, Cr, Zn, Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb.

[0029] In other embodiments, when Mn is solid-dissolved in the main component, barium titanate, the minor component is at least one selected from the group consisting of Mg, Cr, Zn, Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb, excluding Mn.

[0030] As shown in Figure 2, the sample with added minor components exhibits a smaller rate of change in DC aging characteristics compared to the sample with only Cu in a solid solution.

[0031] The content of the aforementioned auxiliary component may be 0.3 to 2.1 moles, 1.0 to 2.1 moles, or 1.5 to 2.1 moles per 100 moles of titanium (Ti) constituting the barium titanate.

[0032] The aforementioned minor component may be at least one donor element selected from the group consisting of Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb. The donor element may be included as an oxide or carbonate.

[0033] The addition of the aforementioned donor element significantly improves the DC aging characteristics. Although the details of the mechanism are not clear, the addition of the aforementioned donor element causes oxygen vacancies (V ｏ The formation of excess oxygen vacancies (V) that are not captured by the solid-solution metal element is reduced. ｏ) decreases, and excess oxygen vacancies (V ｏ ) and the interaction with the metal element creates a defect dipole (D ｄｅｆｅｃｔ ) becomes less likely to change its polarization direction, that is, a defective dipole (D ｄｅｆｅｃｔ This is presumed to be due to improved stability of ).

[0034] For example, as shown in Figure 2, the sample with the donor element Dy added as a minor component shows a smaller rate of change in DC aging compared to the sample with the acceptor element Mg added as a minor component, thus demonstrating improved DC aging characteristics.

[0035] On the other hand, the aforementioned minor component may be at least one acceptor element selected from the group consisting of Mg, Mn, Cr, and Zn. The acceptor element may be included as an oxide or carbonate.

[0036] The addition of the aforementioned acceptor element further improves the DC bias characteristics. Although the details of the mechanism are not clear, when the acceptor element is added, the defect dipole (D ｄｅｆｅｃｔ Oxygen vacancies (V) necessary for the formation of ) ｏ ) increases, and defective dipoles (D ｄｅｆｅｃｔ This is presumed to be due to the promotion of the formation of ).

[0037] As shown in Figure 3, the sample with Mg, an acceptor element, added as a minor component shows that the dielectric constant peak is located on the high-field side, and the DC bias characteristics on the high-field side are improved, compared to the sample with W, a donor element, added as a minor component.

[0038] The aforementioned minor component may include both at least one acceptor element selected from the group consisting of Mg, Mn, Cr, and Zn, and at least one donor element selected from the group consisting of Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb. Both the acceptor element and the donor element may be contained in barium titanate as oxides or carbonates. By including both the acceptor element and the donor element as a minor component, it is possible to obtain both the improvement effect of DC bias characteristics due to the addition of the acceptor element and the improvement effect of DC aging characteristics due to the addition of the donor element.

[0039] For example, if both the acceptor element and the donor element are included, the acceptor element may be present in an amount of 0.15 to 1.5 moles per 100 moles of titanium (Ti) constituting the barium titanate, and the donor element may be present in an amount of 0.15 to 0.6 moles per 100 moles of titanium (Ti) constituting the barium titanate.

[0040] As shown in Figure 4, including both acceptor and donor elements as minor components significantly improves the DC aging characteristics compared to other samples.

[0041] As shown in Figure 5, even if the amount of Dy added increases, there is no significant difference in the dielectric constant on the high-field side.

[0042] On the other hand, as shown in Figure 6, the rate of change in DC aging characteristics decreases as the amount of Dy added increases.

[0043] When the aforementioned subcomponents include both an acceptor element and a donor element, the acceptor element may be Mg, and the donor element may be at least one selected from the group consisting of Gd, Tb, Dy, Ho, Y, and Er. In particular, the donor element may be at least one selected from the group consisting of Dy, Tb, and Gd. In this case, the improvement effect on DC aging characteristics is more pronounced.

[0044] As shown in Figure 7, the samples with Dy and Gd added, respectively, show a significant reduction in DC aging changes compared to samples with other elements added. Similarly, Tb, which has an ionic radius similar to Dy and Gd, also shows a reduction in DC aging changes. Therefore, when the donor element is selected from the group consisting of Dy, Tb, and Gd, the improvement in DC aging characteristics is even more pronounced.

[0045] When the acceptor element is added as the aforementioned minor component, the total content (Y moles) of the metal element in terms of molar mass and the content (X moles) of the acceptor element in terms of molar mass are considered. ｎ＋ Moles) are X ｎ＋ The relationship ≥Y / 4-n may also be satisfied.

[0046] By satisfying the above relationship, the oxygen vacancies (V) in the metal element ｏ The supply amount of ) becomes optimal, and the spontaneous polarization of barium titanate and the aforementioned defect dipole (D ｄｅｆｅｃｔ The interaction between these factors enhances the improvement effect on DC bias characteristics.

[0047] Figures 1-7 show measurement results using a sample in which the metal element dissolved in barium titanate, the main component, is Cu, but the example is not limited to this. For example, the metal element dissolved in barium titanate may be Fe or Mn. Even when Fe or Mn is dissolved in barium titanate, the oxygen vacancies (V) are similar to those when Cu is dissolved. ｏ ) and defective dipole (D ｄｅｆｅｃｔ A compound is formed, and the addition of a minor component improves the DC bias characteristics and also improves the DC aging characteristics.

[0048] For example, as shown in Figure 8, regardless of whether Cu, Fe, or Mn is used as a solid solution, adding a minor component results in a smaller DC aging change rate and improved DC aging characteristics compared to not adding a minor component. This is especially true for Cu, where the DC aging change rate is significantly reduced.

[0049] The DC bias characteristics and DC aging characteristics shown in Figures 2 to 8 were measured as follows: The DC bias characteristics were calculated using ((C2 - C1) / C1) × 100 (%), where C1 is the capacitance when no DC voltage is applied under the conditions of 25°C, 100Hz, and 0.1V / μm AC voltage, and C2 is the capacitance when a DC voltage is applied under the conditions of 25°C, 100Hz, and 0.1V / μm AC voltage. The DC aging characteristics were calculated using ((C3 - C2) / C2) × 100 (%), where C3 is the capacitance at each measurement time, after continuously measuring the capacitance at regular intervals with a DC voltage of 2.0V / μm applied.

[0050] [Multilayer Ceramic Capacitor] A multilayer ceramic capacitor in one embodiment comprises a capacitor body in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately stacked, and an external electrode provided on the end face of the capacitor body where the plurality of internal electrode layers are exposed, wherein the plurality of dielectric layers contain the dielectric ceramic composition described above. The plurality of internal electrode layers may use various metal elements such as Ni, Pd, Ag, and Cu as the main component. As an example, the main component of the plurality of internal electrode layers is Ni. The external electrode has a base layer connected to the capacitor body and a plated outer layer that facilitates soldering of external wiring to the external electrode.

[0051] In one embodiment, the multilayer ceramic capacitor may contain at least one metal element selected from the group consisting of Cu, Fe, and Mn in the plurality of dielectric layers and the plurality of internal electrode layers. In this case, the content of the metal element in the plurality of internal electrode layers may be greater than the content of the metal element in the plurality of dielectric layers.

[0052] [Method for Manufacturing a Dielectric Porcelain Composition] A method for manufacturing a dielectric porcelain composition in one embodiment includes: mixing a barium titanate raw material with a solid solution component containing at least one metal element selected from the group consisting of Cu, Fe, and Mn in an amount of 0.5 moles or more per 100 moles of titanium (Ti) to obtain a mixture; adding a minor component to the mixture containing at least one selected from the group consisting of Mg, Mn, Cr, Zn, Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb; and firing the mixture to which the minor component has been added.

[0053] In this disclosure, the raw material for barium titanate is BaTiO ３ It can be that thing, BaTiO ３ Raw materials before production, for example, BaCO ３ and TiO ２ It may also be used to select the solid solution component from BaCO3. ３ and TiO ２ It can be mixed with BaTiO beforehand. ３ The solid solution components may be mixed in the prepared state. In order to include 0.5 moles or more of the metal element in the solid solution components per 100 moles of titanium (Ti) that constitutes barium titanate, it is necessary to efficiently solid dissolve the metal element in barium titanate. For this purpose, the solid solution components may be mixed in BaTiO ３ Raw materials before production (e.g., BaCO3) ３ and TiO ２ It is best to mix it with ) and calcine it before performing the addition and calcination described later. BaTiO ３ When solid solution components are mixed with the material itself, some of the solid solution components do not dissolve in barium titanate and segregate, reducing the amount of metal elements that dissolve, making it difficult to efficiently dissolve the metal elements in barium titanate. On the other hand, if the solid solution components are prepared in advance using BaCO3 ３ and TiO ２ When adding auxiliary components after mixing and calcining, the BaTiO after calcination ３This method allows for more efficient solid dissolution of metal elements into barium titanate compared to mixing solid solution components with the material itself. With this manufacturing method, the amount of solid solution in barium titanate is greater than the amount of segregation that occurs without solid dissolution. As a result, the defect dipole (D) is reduced. ｄｅｆｅｃｔ This promotes the formation of ) and improves the DC bias characteristics.

[0054] The minor component may be the donor element, the acceptor element, or a combination of both. The minor component may be added simultaneously with the mixing of the barium titanate raw material and the metal element, or after the mixing.

[0055] For example, the minor component may be at least one donor element selected from the group consisting of Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb. Alternatively, the minor component may be at least one acceptor element selected from the group consisting of Mg, Mn, Cr, and Zn. Furthermore, the minor component may contain both at least one acceptor element selected from the group consisting of Mg, Mn, Cr, and Zn, and at least one donor element selected from the group consisting of Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb.

[0056] When the acceptor element is added as the aforementioned minor component, the total content (Y moles) of Cu, Fe, Fe, Mn, and Mn in terms of molar amount, and the content (X moles) of the acceptor element in terms of molar amount, are considered. ｎ＋ Mole) is X ｎ＋ The relationship ≥Y / 4-n may also be satisfied.

[0057] In addition, components other than the aforementioned minor components may be added. For example, additives containing metal elements other than those listed as minor components may be added. Furthermore, for example, binders and organic solvents such as ethanol may be added.

[0058] The firing conditions are not particularly limited. For example, a debinder treatment may be performed at 300°C in air at a heating rate of 10°C / hour, followed by heating at the same heating rate, then firing at 1150°C for 2 hours in a hydrogen-nitrogen gas mixture at a heating rate of 300°C / hour from 500°C, followed by cooling to 1000°C at a cooling rate of 300°C / hour, then a re-oxidation treatment at 1000°C in a nitrogen atmosphere for 4 hours, and finally cooling at a cooling rate of 300°C / hour. The valence of the metal element can be changed depending on the conditions of the re-oxidation treatment (atmosphere and / or temperature, etc.).

[0059] The mixture to which the aforementioned auxiliary components have been added may be calcined before the aforementioned firing.

[0060] The aforementioned calcination may be performed at 800 to 1000°C for 1 to 20 hours.

[0061] A ceramic green sheet, which will later become the dielectric layer, is formed by mixing solid solution components with barium titanate raw materials and adding auxiliary components. When this ceramic green sheet is laminated with a conductive paste, which will later become the internal electrode layer, and fired, the solid-solution metal elements diffuse into the conductive paste, reducing the amount of solid-solution metal elements within the ceramic green sheet, resulting in the formation of defect dipoles (D ｄｅｆｅｃｔ The formation of a defect dipole (D) is inhibited. Therefore, by performing the calcination, the diffusion of the solid-solution metal element into the conductive paste during firing is reduced, making it possible to increase the content of metal elements in the internal electrode layer after firing compared to the content of metal elements in the dielectric layer after firing. As a result, defect dipoles (D) are inhibited. ｄｅｆｅｃｔ This promotes the formation of ), which in turn improves DC bias characteristics and DC aging characteristics.

[0062] [Method for manufacturing multilayer ceramic capacitors] In one embodiment, the multilayer ceramic capacitor may be manufactured as follows.

[0063] First, the dielectric ceramic composition is mixed with an organic resin such as polyvinyl butyral resin and a solvent such as toluene and alcohol to prepare a ceramic slurry using a ball mill or the like. Then, a ceramic green sheet is formed on a substrate using a sheet molding method such as the doctor blade method or the die coater method.

[0064] The thickness of the ceramic green sheet may be 0.5 to 10 μm. By setting the thickness of the ceramic green sheet to 0.5 to 10 μm, it is possible to thin the dielectric layer to increase its capacitance while maintaining high insulation properties.

[0065] Next, a conductive paste forming a rectangular internal electrode pattern is printed onto the main surface of the obtained ceramic green sheet. The conductive paste is prepared by mixing Ni or its alloy powder as the main metal component with ceramic powder as a co-material, and adding an organic binder, solvent, and dispersant.

[0066] Next, a desired number of ceramic green sheets with conductive paste formed on them are stacked, and several ceramic green sheets without internal electrode layers are stacked above and below them to form a temporary laminate. The internal electrode patterns in the temporary laminate are offset by half a pattern in the longitudinal direction. This lamination method allows the internal electrode patterns to be alternately exposed on the end faces of the laminate after cutting.

[0067] Next, the temporary laminate is pressed under conditions of higher temperature and pressure than those used during the temporary lamination process, forming a laminate in which the ceramic green sheet and conductive paste are firmly bonded together.

[0068] Next, by cutting the laminated material in a grid pattern, a capacitor body molded into which the ends of the internal electrode pattern, which is a conductive paste, are exposed is formed.

[0069] Next, the capacitor body molded body is fired under predetermined atmospheric and temperature conditions to form the capacitor body. In some cases, the edges of the capacitor body may be chamfered, and barrel polishing may be performed to expose the internal electrode layer exposed from the opposing end faces of the capacitor body.

[0070] Next, the resulting capacitor body is degreased and then fired.

[0071] Next, external electrode paste is applied to the opposing ends of the capacitor body and baked to form external electrodes. In some cases, a plating film is also formed on the surface of these external electrodes to improve mountability. In this way, a multilayer ceramic capacitor is obtained.

[0072] Since the multilayer ceramic capacitor of this embodiment uses the dielectric ceramic composition as the raw material for the dielectric layer, both DC bias characteristics and DC aging characteristics can be improved.

Claims

1. A dielectric ceramic composition comprising barium titanate as the main component, containing at least one metal element selected from the group consisting of Cu and Fe in a solid solution with respect to 0.5 moles or more per 100 moles of titanium constituting the barium titanate, and containing a minor component comprising at least one selected from the group consisting of Mg, Mn, Cr, Zn, Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb.

2. The aforementioned metal element is Cu ３＋ Fe ３＋ and Fe ２＋ The dielectric ceramic composition according to claim 1, comprising a metal ion containing at least one selected from the group consisting of the above, in solid solution with barium titanate.

3. The dielectric ceramic composition according to claim 1 or 2, wherein the composition contains 0.3 to 2.1 moles of the auxiliary component with respect to 100 moles of titanium (Ti) constituting the barium titanate.

4. The dielectric ceramic composition according to any one of claims 1 to 3, wherein the minor component is at least one donor element selected from the group consisting of Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb.

5. The dielectric ceramic composition according to any one of claims 1 to 3, wherein the minor component is at least one acceptor element selected from the group consisting of Mg, Mn, Cr, and Zn.

6. The dielectric ceramic composition according to any one of claims 1 to 3, wherein the minor component comprises both at least one acceptor element selected from the group consisting of Mg, Mn, Cr, and Zn, and at least one donor element selected from the group consisting of Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb.

7. The dielectric ceramic composition according to claim 6, wherein the acceptor element is Mg and the donor element is at least one selected from the group consisting of Dy, Tb, and Gd.

8. The dielectric ceramic composition according to claim 6 or 7, wherein it contains 0.15 to 1.5 moles of the acceptor element and 0.15 to 0.6 moles of the donor element per 100 moles of titanium (Ti) constituting the barium titanate.

9. The total content (Y moles) of the aforementioned metal element and the content (X moles) of the aforementioned acceptor element. ｎ＋ Moles) are X ｎ＋ A dielectric ceramic composition according to any one of claims 5 to 8, satisfying the relationship ≥ Y / 4 - n.

10. A dielectric ceramic composition comprising barium titanate as the main component, containing at least 0.5 moles of Mn element in solid solution with respect to 100 moles of titanium constituting the barium titanate, and containing at least one minor component selected from the group consisting of Mg, Cr, Zn, Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb.

11. The aforementioned Mn element is Mn ３＋ and Mn ２＋ The dielectric ceramic composition according to claim 10, which is at least one selected from the group consisting of the following.

12. A multilayer ceramic capacitor having a capacitor body in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately stacked, and an external electrode provided on the end face of the capacitor body where the internal electrode layers are exposed, wherein the plurality of dielectric layers include the dielectric ceramic composition described in claim 1 or 10.

13. The multilayer ceramic capacitor according to claim 12, wherein the metal element is contained in all of the plurality of dielectric layers and the plurality of internal electrode layers, and the content of the metal element contained in the plurality of internal electrode layers is greater than the content of the metal element contained in the plurality of dielectric layers.

14. A method for producing a dielectric ceramic composition, comprising: mixing a barium titanate raw material with a solid solution component containing at least one metal element selected from the group consisting of Cu, Fe, and Mn in an amount of 0.5 moles or more per 100 moles of titanium (Ti) to obtain a mixture; adding a minor component to the mixture containing at least one selected from the group consisting of Mg, Mn, Cr, Zn, Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb; and firing the mixture to which the minor component has been added.

15. A method for producing a dielectric porcelain composition according to claim 14, comprising calcining the mixture to which the auxiliary components have been added before firing.

16. The method for producing a dielectric ceramic composition according to claim 14 or 15, wherein the minor component is at least one donor element selected from the group consisting of Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb.

17. The method for producing a dielectric ceramic composition according to claim 14 or 15, wherein the minor component is at least one acceptor element selected from the group consisting of Mg, Mn, Cr, and Zn.

18. A method for producing a dielectric ceramic composition according to claim 14 or 15, wherein the minor component comprises both at least one acceptor element selected from the group consisting of Mg, Mn, Cr, and Zn, and at least one donor element selected from the group consisting of Mo, Ta, W, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, and Yb.

19. The method for producing a dielectric ceramic composition according to claim 18, wherein the acceptor element is Mg and the donor element is at least one selected from the group consisting of Dy, Tb, and Gd.

20. The total content in terms of the amount of substance of the metal element (Y mol) and the content in terms of the amount of substance of the acceptor element (X ｎ＋ mol) satisfy the relationship of X ｎ＋ ≧ Y / 4 - n, and the method for manufacturing a dielectric porcelain composition according to any one of claims 17 to 19.

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