Dielectric body, multilayer ceramic capacitor, manufacturing method of dielectric body, and manufacturing method of multilayer ceramic capacitor

Abstract

The objective of this invention is to provide a dielectric material that can achieve both high lifespan and excellent capacitance temperature characteristics, a multilayer ceramic capacitor, a method for manufacturing the dielectric material, and a method for manufacturing the multilayer ceramic capacitor. The dielectric of the present invention comprises a plurality of grains mainly composed of barium titanate, and contains Zr, Eu, and Mn as additives. At least one of the plurality of grains has a core-shell structure, which includes a core mainly composed of barium titanate and an outer shell mainly composed of barium titanate with a Zr concentration higher than that of the core. The Zr / Ti atomic concentration ratio is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, and the Mn / Ti atomic concentration ratio is 0.005 to 0.05. The atomic concentration of the other rare earth elements is smaller than that of Eu. The median grain size of the plurality of grains is 200 nm to 400 nm.

Description

Technical Field

[0001] This invention relates to a dielectric, a multilayer ceramic capacitor, a method for manufacturing the dielectric, and a method for manufacturing the multilayer ceramic capacitor. Prior Technology

[0002] In high-frequency communication systems, such as mobile phones, multilayer ceramic capacitors are used to remove noise. Multilayer ceramic capacitors are also used in electronic circuits related to human life, such as in vehicle electronic control devices. Because multilayer ceramic capacitors require high reliability, technologies to improve reliability have been disclosed (for example, see Patent Documents 1-5). [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-114751 [Patent Document 2] Japanese Patent Application Publication No. 2018-90458 [Patent Document 3] Japanese Patent Application Publication No. 2019-131438 [Patent Document 4] Japanese Patent Application Publication No. 2016-169130 [Patent Document 5] Japanese Patent Application Publication No. 2015-187969 Summary of the Invention

[0004] [The problem the invention aims to solve]

[0005] In the dielectric of multilayer ceramic capacitors, a core-shell sintered body is utilized. This core-shell sintered system uses barium titanate as the core, surrounded by a shell containing various additives dissolved in solid solution. This is because it yields a material with excellent capacitance temperature characteristics and a stable microstructure that coexists even during the calcination process. Mg (magnesium) is a representative additive constituting the shell. However, Mg is a single acceptor with an invariant valence, and under electroneutrality conditions, it generates oxygen defects that are known to adversely affect the reliability of multilayer ceramic capacitors. Therefore, it cannot sufficiently improve reliability for high-reliability applications.

[0006] Subsequently, in high-reliability applications, multilayer ceramic capacitors capable of operating at temperatures up to 150°C are required. However, barium titanate, the main component of the dielectric layer, has a Curie point of approximately 125°C. Capacitance decreases significantly above this point, making it impossible to meet the EIA (Electronic Industries Association) standard temperature characteristic X8R (capacitance change from -55°C to 150°C within ±15% of the 25°C capacitance) without specific methods. One approach to improve this is to add Yb (ytterbium) to the dielectric layer to shift the Curie point towards higher temperatures and thus meet X8R. However, Yb acts as an acceptor, and like Mg, it cannot provide sufficient reliability for high-reliability applications. Another method involves mixing BaTi₂O₅ (470°C), which has a high Curie point, with BaTiO₃. However, BaTi₂O₅ has a low relative permittivity at room temperature, preventing it from achieving high capacitance.

[0007] The present invention was made in view of the above-mentioned problems, and its purpose is to provide a dielectric material that can take into account both long life and excellent capacitance temperature characteristics, a multilayer ceramic capacitor, a method for manufacturing the dielectric material, and a method for manufacturing the multilayer ceramic capacitor. [Technical means to solve the problem]

[0008] The dielectric of the present invention is characterized in that it comprises a plurality of grains mainly composed of barium titanate, and contains Zr, Eu, and Mn as additives. At least one of the plurality of grains has a core-shell structure, which includes a core portion mainly composed of barium titanate and an outer shell portion mainly composed of barium titanate with a Zr concentration higher than that of the core portion. The Zr / Ti atomic concentration ratio is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, and the Mn / Ti atomic concentration ratio is 0.005 to 0.05. The atomic concentration of the other rare earth elements is smaller than that of Eu. The median grain size of the plurality of grains is 200 nm to 400 nm.

[0009] In the above dielectric, the rare earth element contained as the additive in the above plurality of grains may be only Eu.

[0010] The multilayer ceramic capacitor of the present invention is characterized by having a multilayer structure formed in such a way that dielectric layers and internal electrode layers are alternately stacked, having a generally cuboid shape, wherein a plurality of the stacked internal electrode layers are alternately exposed on two different faces, and the dielectric layer in the capacitor region where the internal electrode layers exposed on the two different faces face each other comprises a plurality of grains mainly composed of barium titanate, and contains Zr, Eu, and Mn as additives, and at least one of the plurality of grains has a core. The core-shell structure comprises a core mainly composed of barium titanate and an outer shell mainly composed of barium titanate with a higher Zr concentration than the core. The Zr / Ti atomic concentration ratio is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, and the Mn / Ti atomic concentration ratio is 0.005 to 0.05. Compared with the Eu atomic concentration, the total atomic concentration of other rare earth elements is small. The median grain size of the plurality of grains is 200 nm to 400 nm.

[0011] The above-mentioned multilayer ceramic capacitors can meet the X8R characteristics.

[0012] The method for manufacturing the dielectric of the present invention is characterized by: calcining a dielectric preform at a heating rate of 5000℃ / h to 10000℃ / h to obtain a dielectric containing a plurality of grains mainly composed of barium titanate, wherein the median grain size of the plurality of grains is 200 nm to 400 nm. The dielectric preform contains barium titanate powder and contains Zr, Eu, and Mn as additives. The Zr / Ti atomic concentration ratio is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, and the Mn / Ti atomic concentration ratio is 0.005 to 0.05. The total atomic concentration of other rare earth elements is smaller than that of Eu.

[0013] The manufacturing method of the multilayer ceramic capacitor of the present invention is characterized by the following steps: multilayering multiple multilayer units printed with metal conductive paste on a dielectric blank to obtain a ceramic multilayer body; wherein the dielectric blank contains barium titanate powder and contains Zr, Eu, and Mn as additives, the Zr / Ti atomic concentration ratio is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, and the Mn / Ti atomic concentration ratio is 0.005 to 0.05, and the total atomic concentration of other rare earth elements is smaller than that of Eu; and the ceramic multilayer body is calcined by heating at a heating rate of 5000°C / h to 10000°C / h to form a dielectric layer containing a plurality of grains mainly composed of barium titanate, wherein the median grain size of the plurality of grains is 200 nm to 400 nm. [Effects of the Invention]

[0014] According to the present invention, a dielectric material capable of achieving both high lifespan and excellent capacitance temperature characteristics, a multilayer ceramic capacitor, a method for manufacturing the dielectric material, and a method for manufacturing the multilayer ceramic capacitor are provided. Simple Explanation of the Diagram

[0015] Figure 1 is a partial cross-sectional perspective view of a multilayer ceramic capacitor. Figure 2 is a cross-sectional view along line AA of Figure 1. Figure 3 is a cross-sectional view along line BB of Figure 1. Figure 4(a) is an illustration of a core-shell particle, and (b) is a schematic cross-sectional view of the dielectric layer. Figure 5 is a flowchart illustrating the manufacturing method of multilayer ceramic capacitors. Figure 6 is a SEM (Scanning Electron Microscope) image of the stacked cross-section of the dielectric layer and the internal electrode layer of the capacitor region in Example 1. Figure 7 shows a TEM (Transmission Electron Microscope) image of the dielectric layer in the capacitor region. Figure 8(a) shows the TEM-EDS (Energy Dispersive X-ray Spectroscopy) analysis results for the outer shell, and (b) shows the TEM-EDS analysis results for the core. Figure 9 is a SEM image of the stacked cross-section of the dielectric layer and the internal electrode layer of the capacitor region in Comparative Example 12. Implementation

[0016] The implementation method will now be described with reference to the drawings.

[0017] (Implementation Method) Figure 1 is a partial cross-sectional perspective view of the multilayer ceramic capacitor 100 according to an embodiment. Figure 2 is a cross-sectional view along line AA of Figure 1. Figure 3 is a cross-sectional view along line BB of Figure 1. As illustrated in Figures 1-3, the multilayer ceramic capacitor 100 includes: a multilayer wafer 10 having a generally rectangular parallelepiped shape; and external electrodes 20a and 20b disposed on either of two opposing end faces of the multilayer wafer 10. Furthermore, of the four surfaces of the multilayer wafer 10 other than the two end faces, the two surfaces other than the upper and lower surfaces in the stacking direction are referred to as side surfaces. The external electrodes 20a and 20b extend to the upper surface, lower surface, and two side surfaces in the stacking direction of the multilayer wafer 10. However, the external electrodes 20a and 20b are spaced apart from each other.

[0018] The multilayer wafer 10 has a configuration in which dielectric layers 11, comprising ceramic material that functions as a dielectric, and internal electrode layers 12, comprising base metal material, are alternately deposited. The edges of each internal electrode layer 12 are alternately exposed on the end face of the multilayer wafer 10 where external electrodes 20a and 20b are disposed. Thus, each internal electrode layer 12 is alternately connected to the external electrodes 20a and 20b. As a result, the multilayer ceramic capacitor 100 has a configuration in which a plurality of dielectric layers 11 are deposited, separating the internal electrode layers 12. Furthermore, in the multilayer body of dielectric layers 11 and internal electrode layers 12, the internal electrode layers 12 are disposed on the outermost layer in the stacking direction, and the upper and lower surfaces of this multilayer body are covered by a capping layer 13. The capping layer 13 is primarily composed of ceramic material. For example, the material of the capping layer 13 has the same primary component as the ceramic material of the dielectric layer 11. Furthermore, as long as the internal electrode layer 12 is exposed on two different surfaces and connected to different external electrodes, it is not limited to the configuration shown in Figures 1 to 3.

[0019] The dimensions of the multilayer ceramic capacitor 100 are, for example, a length of 0.25 mm, a width of 0.125 mm, and a height of 0.125 mm; or a length of 0.4 mm, a width of 0.2 mm, and a height of 0.2 mm; or a length of 0.6 mm, a width of 0.3 mm, and a height of 0.3 mm; or a length of 1.0 mm, a width of 0.5 mm, and a height of 0.5 mm; or a length of 3.2 mm, a width of 1.6 mm, and a height of 1.6 mm; or a length of 4.5 mm, a width of 3.2 mm, and a height of 2.5 mm, but are not limited to these dimensions.

[0020] The internal electrode layer 12 is primarily composed of base metals such as Ni, Cu, and Sn. Noble metals such as Pt, Pd, Ag, and Au, or alloys containing these metals, can also be used as the internal electrode layer 12. The thickness of the internal electrode layer 12 is, for example, 0.1 μm to 3 μm, 0.1 μm to 1 μm, or 0.1 μm to 0.5 μm.

[0021] The dielectric layer 11 is, for example, a ceramic material having a perovskite structure represented by the general formula ABO3 as the main phase. Furthermore, this perovskite structure contains ABO3-α, deviating from its stoichiometric composition. In this embodiment, the ceramic material used contains at least Ba (barium) at site A and at least Ti (titanium) at site B. Site B may also contain Zr (zirconium). The thickness of the dielectric layer 11 is, for example, 0.2 μm to 10 μm, 0.2 μm to 5 μm, or 0.2 μm to 2 μm.

[0022] As illustrated in Figure 2, the regions where the inner electrode layer 12 connected to the external electrode 20a and the inner electrode layer 12 connected to the external electrode 20b face each other are the regions in the multilayer ceramic capacitor 100 that generate capacitance. Therefore, this region that generates capacitance is called the capacitance region 14. That is, the capacitance region 14 is the region where adjacent inner electrode layers 12 connected to different external electrodes face each other.

[0023] The region where the internal electrode layers 12 connected to the external electrode 20a are connected to each other without any separation between them and the internal electrode layers 12 connected to the external electrode 20b, and which face each other, is called the end edge 15. Similarly, the region where the internal electrode layers 12 connected to the external electrode 20b are connected to each other without any separation between them and the internal electrode layers 12 connected to the external electrode 20a, and which face each other, is also called the end edge 15. In other words, the end edge 15 is the region where the internal electrode layers 12 connected to the same external electrode face each other without any separation between them and the internal electrode layers 12 connected to different external electrodes. The end edge 15 is a region that does not generate capacitance.

[0024] As illustrated in Figure 3, in the stacked wafer 10, the region extending from the two sides of the stacked wafer 10 to the internal electrode layer 12 is referred to as the side edge 16. That is, the side edge 16 is a region provided in such a way that it covers the ends of the plurality of internal electrode layers 12 stacked in the above-described stacked structure that extend to the two sides. The side edge 16 is also a region that does not generate capacitance.

[0025] In the capacitance region 14 of this multilayer ceramic capacitor 100, if at least a portion of the barium titanate grains contained in the dielectric layer 11 have a core-shell structure, then the dielectric layer 11 in the capacitance region 14 has a high dielectric constant, excellent temperature characteristics, and a stable microstructure.

[0026] Mg is a representative additive that constitutes the outer shell. However, Mg is a single acceptor with an invariant valence. When dissolved in barium titanate of dielectric layer 11, it generates oxygen vacancies, thus limiting its reliability.

[0027] Therefore, in this embodiment, in the capacitor region 14, at least a portion of the barium titanate grains contained in the dielectric layer 11 have a core-shell structure, which has a core portion mainly composed of barium titanate and an outer shell portion composed of a Zr (zirconium) diffusion layer. Furthermore, the outer shell portion is mainly composed of barium titanate.

[0028] As illustrated in Figure 4(a), the core-shell particle 30 has a generally spherical core portion 31 and an outer shell portion 32 that surrounds the core portion 31. The core portion 31 is a crystalline portion in which the added compound is not dissolved or has a low amount of the added compound dissolved. The outer shell portion 32 is a crystalline portion in which the added compound is dissolved and has a higher concentration of the added compound than that in the core portion 31. In this embodiment, the Zr concentration in the outer shell portion 32 is higher than the Zr concentration in the core portion 31. Alternatively, Zr diffuses in the outer shell portion 32 but not in the core portion 31.

[0029] Figure 4(b) is a schematic cross-sectional view of the dielectric layer 11. As illustrated in Figure 4(b), the dielectric layer 11 has a plurality of grains 17 of ceramic as the main component. At least a portion of these grains 17 are the core-shell particles 30 illustrated in Figure 4(a). By covering the core portion 31 with a shell portion 32 of high Zr concentration and high resistance to reduction, a material that maintains a high dielectric constant, has a stable structure, and is highly reliable can be obtained.

[0030] Furthermore, when Zr diffuses and dissolves in barium titanate, if the Zr diffusion layer is thickened to a required thickness to lower the Curie temperature of barium titanate, the capacitance change rate at high temperatures may increase, potentially preventing the multilayer ceramic capacitor 100 from meeting the X8R characteristic. Typically, Zr diffusion in barium titanate leads to rapid grain growth, making it difficult to limit the diffusion layer thickness, suppress grain growth, and achieve the X8R characteristic. For example, if the heating rate in the calcination step is set to approximately 10°C / h, it will excessively promote the diffusion of rare earth elements, forming fully dissolved particles. In this case, while a high lifetime is achieved due to the progress of Zr and rare earth elements' solid solution, a low dielectric constant, decreased sintering stability, and a tendency for poor temperature characteristics of the capacitor are observed. In this embodiment, the Zr diffusion distance is limited, and the Zr concentration in the outer shell 32 is higher than that in the core 31; therefore, the multilayer ceramic capacitor 100 meets the X8R characteristic.

[0031] If the Zr / Ti atomic concentration ratio in the dielectric layer 11 of the capacitor region 14 is too small, the following risks may arise: a core-shell structure with a low Zr concentration core and a high Zr concentration outer shell cannot be maintained, resulting in localized abnormal growth, failing to achieve high lifetime, and failing to obtain X8R characteristics. Therefore, in this embodiment, a lower limit is set for the Zr / Ti atomic concentration ratio. Specifically, the Zr / Ti atomic concentration ratio in the dielectric layer 11 of the capacitor region 14 is set to 0.02 or higher. In this case, the grain size of the grains 17 is approximately uniform, and a stable core-shell structure with a high concentration of Zr elemental distribution in the outer shell 32 can be formed. This Zr / Ti atomic concentration ratio is preferably 0.03 or higher, and more preferably 0.04 or higher.

[0032] On the other hand, if the Zr / Ti atomic concentration ratio in the dielectric layer 11 of the capacitor region 14 is too high, the relative permittivity of the dielectric layer 11 may become low (for example, below 1500), and the X8R characteristics may not be met. Therefore, in this embodiment, an upper limit is set for the Zr / Ti atomic concentration ratio. Specifically, the Zr / Ti atomic concentration ratio in the dielectric layer 11 of the capacitor region 14 is set to 0.10 or less. This allows for a sufficient relative permittivity. This Zr / Ti atomic concentration ratio is preferably 0.08 or less, and more preferably 0.06 or less.

[0033] However, by doping Zr into dielectric layer 11, the lattice constant of barium titanate crystallization is expanded. Rare earth elements such as Ho (E, Dy (Dysprosium)) and Y (Yttrium), which are key to lifetime, are more dissolved in site B than in site A, resulting in an excess of acceptors. Therefore, the lifetime improvement effect is limited.

[0034] Therefore, the inventors studied rare earth elements with large ionic radii that readily replace barium titanate at its A-site. The results showed that by adding Eu, the lifetime increased by approximately one digit compared to rare earth elements such as Ho, Dy, and Y. The reason for the increased lifetime due to the addition of Eu is not entirely clear, but it is believed that Eu is stable in both divalent and trivalent states, and varies between these two states. Among rare earth elements stable in divalent states, Eu has the largest ionic radius, thus selectively replacing the A-site. Furthermore, rare earth elements other than Eu are stable in trivalent states but unstable in divalent states.

[0035] Table 1 shows the ionic radii of the 6-coordinate of each rare earth element. The source of Table 1 is "RD Shannon, Acta Crystallogr., A32, 751 (1976)". [Table 1] Price Ionic radius (Å) 6 coordination 12 coordination Ba +2 price 1.610 Ti +4 price 0.605 Eu +2 price 1.170 Dy +2 price 1.070 La +3 price 1.032 Tm +2 price 1.030 Yb +2 price 1.020 Ce +3 price 1.010 Pr +3 price 0.990 Nd +3 price 0.983 Pm +3 price 0.970 Sm +3 price 0.958 Eu +3 price 0.947 Gd +3 price 0.938 Tb +3 price 0.923 Dy +3 price 0.912 Ho +3 price 0.901 Y +3 price 0.900 Er +3 price 0.890 Tm +3 price 0.880 Yb +3 price 0.868 Lu +3 price 0.861 Sc +3 price 0.745

[0036] Eu is also more dissolved in the outer shell 32 than in the core 31. Therefore, the Eu concentration in the outer shell 32 is higher than that in the core 31.

[0037] If the Eu / Ti atomic concentration ratio in the dielectric layer 11 of the capacitor region 14 is too low, a sufficiently high lifetime may not be achieved. Therefore, in this embodiment, a lower limit is set for the Eu / Ti atomic concentration ratio. Specifically, the Eu / Ti atomic concentration ratio in the dielectric layer 11 of the capacitor region 14 is set to 0.001 or higher. This Eu / Ti atomic concentration ratio is preferably 0.005 or higher, and more preferably 0.01 or higher.

[0038] On the other hand, if the Eu / Ti atomic concentration ratio in the dielectric layer 11 of the capacitor region 14 is too high, the dielectric layer 11 may become semiconductorized, resulting in a low lifetime. Therefore, in this embodiment, an upper limit is set for the Eu / Ti atomic concentration ratio. Specifically, the Eu / Ti atomic concentration ratio in the dielectric layer 11 of the capacitor region 14 is set to 0.03 or less. The Eu / Ti atomic concentration ratio is preferably 0.025 or less, and more preferably 0.02 or less.

[0039] However, by partially dissolving a portion of Eu in a trivalent state at the A site, it risks becoming a donor, potentially worsening insulation. The inventors have discovered that the co-addition of Mn (manganese), which reduces excess electrons, is effective in addressing this issue. Mn not only improves insulation but can also increase its valence through re-oxidation, reducing oxygen vacancies and further extending lifetime. Mn can replace all of Mg as a single acceptor, or a small amount of Mg can remain to utilize its particle size reduction effect. In short, Mn is used as an acceptor, while Mg is kept to a minimum suitable for the design of the structure or other properties.

[0040] If the Mn / Ti atomic concentration ratio in the dielectric layer 11 of the capacitor region 14 is too low, there may be insufficient acceptors in the dielectric layer 11, which could lead to insufficient lifetime due to the semiconductorization of the dielectric layer 11. Therefore, in this embodiment, a lower limit is set for the Mn / Ti atomic concentration ratio. Specifically, the Mn / Ti atomic concentration ratio in the dielectric layer 11 of the capacitor region 14 is set to 0.005 or higher. The Mn / Ti atomic concentration ratio is preferably 0.01 or higher, and more preferably 0.02 or higher.

[0041] On the other hand, if the Mn / Ti atomic concentration ratio in the dielectric layer 11 of the capacitor region 14 is too high, there is a risk of excessive acceptors leading to excessive oxygen vacancies and reduced lifetime. Therefore, in this embodiment, an upper limit is set for the Mn / Ti atomic concentration ratio. Specifically, the Mn / Ti atomic concentration ratio in the dielectric layer 11 of the capacitor region 14 is set to 0.05 or less. Preferably, the Mn / Ti atomic concentration ratio is 0.04 or less, and more preferably 0.03 or less.

[0042] Furthermore, when additives such as Zr or Mn are dissolved in barium titanate, the Curie temperature of barium titanate may shift to a lower temperature side below 125°C, potentially leading to a decrease in capacitance at high temperatures. On the other hand, in this embodiment, the Curie point shifts to a higher temperature side above 125°C (e.g., 130°C), thus suppressing the decrease in capacitance at high temperatures, and the multilayer ceramic capacitor 100 satisfies the X8R characteristic. The reason for the shift of the Curie point to the higher temperature side is not entirely clear, but it is speculated to be due to the following factors: the core portion 31, which shrinks the lattice by having a portion of Eu extending beyond the outer shell portion 32 and dissolved into the core portion 31, and the outer shell portion 32, which expands the lattice by the diffusion of a high concentration of Zr-rich additives, thereby generating internal stress at these interfaces.

[0043] In the dielectric layer 11, whether the grain size is too small or too large, the capacitance change rate increases, and the multilayer ceramic capacitor 100 may not achieve the X8R characteristic. Therefore, in this embodiment, a lower limit and an upper limit are set for the median grain size of the grains 17 in the dielectric layer 11 of the capacitor region 14. Specifically, the median grain size of the grains 17 in the dielectric layer 11 of the capacitor region 14 is set to 200 nm or more and 400 nm or less. By keeping the median grain size within this range, the temperature change rate above the Curie point can be suppressed. The median grain size of the grains 17 in the dielectric layer 11 of the capacitor region 14 is preferably 250 nm or more, and more preferably 300 nm or more. On the other hand, the median grain size of the grains 17 in the dielectric layer 11 of the capacitor region 14 is preferably 375 nm or less, and more preferably 350 nm or less.

[0044] Subsequently, if the amount of rare earth elements other than Eu added to the dielectric layer 11 of the capacitor region 14 is too large, the lifetime improvement effect obtained by using Eu may be weakened, and sufficient lifetime may not be obtained. Therefore, in this embodiment, an upper limit is set on the amount of rare earth elements other than Eu added. Specifically, in the dielectric layer 11 of the capacitor region 14, the atomic concentration of rare earth elements other than Eu is less than the atomic concentration of Eu. When there are multiple rare earth elements other than Eu, the total atomic concentration of these multiple rare earth elements is less than the atomic concentration of Eu.

[0045] As described above, according to this embodiment, at least one grain of the dielectric layer 11 of the capacitor region 14 has a core-shell structure. The core-shell structure has a core portion 31 mainly composed of barium titanate and an outer shell portion 32 mainly composed of barium titanate with a Zr concentration higher than that of the core portion 31. In the dielectric layer 11 of the capacitor region 14, the Zr / Ti atomic concentration ratio is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, and the Mn / Ti atomic concentration ratio is 0.005 to 0.05. Compared with the atomic concentration of Eu, the total atomic concentration of other rare earth elements is small. The median grain size of the grains 17 in the dielectric layer 11 of the capacitor region 14 is 200 nm to 400 nm, thereby achieving both high lifetime and excellent capacitor temperature characteristics.

[0046] Next, the manufacturing method of the multilayer ceramic capacitor 100 will be described. Figure 5 is a flowchart illustrating the manufacturing method of the multilayer ceramic capacitor 100.

[0047] (Steps for preparing raw material powder) First, a dielectric material for forming the dielectric layer 11 is prepared. The A-site elements and B-site elements contained in the dielectric layer 11 are typically included in the dielectric layer 11 in the form of a sintered body of ABO3 particles. For example, BaTiO3 is a tetragonal compound with a perovskite structure, exhibiting a high dielectric constant. This BaTiO3 can usually be obtained by reacting titanium raw materials such as titanium dioxide with barium raw materials such as barium carbonate to synthesize barium titanate. Various methods are known for synthesizing the ceramic as the main component of the dielectric layer 11, such as solid-state methods, sol-gel methods, and hydrothermal methods. In this embodiment, any of these methods can be used.

[0048] The obtained ceramic powder is then mixed with specified additive compounds according to the intended purpose. Examples of such additive compounds include oxides of Zr, Mg, Mn, V (vanadium), Cr (chromium), and Eu, as well as oxides or glasses of Co (cobalt), Ni, Li (lithium), B (boron), Na (sodium), K (potassium), and Si (silicon). Oxides of rare earth elements other than Eu (Sc (scandium), Y, La (lanthanum), Ce (cerium), Pr (titanium), Nd (neodymium), Pm (phosphorus), Sm (samarium), Gd (sodium), Tb (tibium), Dy, Ho, Er (erbium), Tm (thorium), Yb, and Lu (diuronium)) may also be added as needed.

[0049] For example, ceramic materials are prepared by wet mixing of a compound containing additives into ceramic raw material powder, followed by drying and pulverization. For example, the particle size of the ceramic material obtained in the above manner can be adjusted by pulverization as needed, or by combining it with a classification process. Dielectric materials are obtained through the above steps. In the dielectric material, the Zr / Ti atomic concentration ratio is set to 0.02 to 0.10, the Eu / Ti atomic concentration ratio is set to 0.001 to 0.03, and the Mn / Ti atomic concentration ratio is set to 0.005 to 0.05, resulting in a lower total atomic concentration of other rare earth elements compared to the Eu atomic concentration.

[0050] (Layering steps) Subsequently, binders such as polyvinyl butyral (PVB) resin, organic solvents such as ethanol and toluene, and plasticizers are added to the obtained dielectric material and wet-mixed. Using the obtained slurry, a strip-shaped dielectric preform with a thickness of, for example, 0.5 μm or more is coated onto the substrate by, for example, die coating or doctor blade coating and then dried.

[0051] Subsequently, using screen printing, gravure printing, or similar methods, a conductive metal paste containing an organic binder is printed onto the surface of the dielectric preform to form internal electrodes, thereby configuring an internal electrode layer pattern that is alternately drawn to a pair of external electrodes with different polarities. Ceramic particles are added to the conductive metal paste as a similar material. The main component of the ceramic particles is not particularly limited, but it is preferably the same as the main component ceramic of the dielectric layer 11. For example, BaTiO3 with an average particle size of less than 50 nm can be uniformly dispersed.

[0052] Subsequently, the dielectric blank printed with the internal electrode layer pattern is punched to a specified size. With the substrate removed, the punched dielectric blank is laminated with a specified number of layers (e.g., 100-1000 layers) in a manner alternating between the internal electrode layer 12 and the dielectric layer 11, with the edge of the internal electrode layer 12 alternately exposed on both ends of the dielectric layer 11 along its length and alternately led out to one of the external electrodes 20a and 20b of different polarities. A cover sheet to form the cover layer 13 is then pressed onto the laminated dielectric blank and cut to a specified wafer size (e.g., 1.0 mm × 0.5 mm).

[0053] (Calcination step) The ceramic laminate obtained in this way is treated with a debinding agent under a N2 atmosphere, and then coated with a metal paste to form the bottom layer of the external electrodes 20a and 20b by an impregnation method. The laminate is then calcined for 5 to 10 minutes under a reducing atmosphere with an oxygen partial pressure of 10⁻¹² MPa to 10⁻⁹ MPa and a temperature of 1160°C to 1280°C.

[0054] Furthermore, if the heating rate is set to a slow rate of around 10°C / h, the diffusion of rare earth elements and Zr in the barium titanate dielectric material is promoted, thereby forming fully solid-solid particles. In this case, although a high lifetime is obtained, the dielectric constant tends to decrease, and the sintering stability and capacitance temperature characteristics tend to deteriorate. Therefore, in this embodiment, by setting the heating rate to between 5000°C / h and 10000°C / h (for example, 6000°C / h), the diffusion of Zr can be suppressed, forming a core-shell structure with a large Zr concentration gradient.

[0055] Furthermore, by adjusting the calcination conditions such as the particle size, calcination temperature, and calcination time of the barium titanate powder in the dielectric material, the median particle size of the grains 17 in the dielectric layer 11 of the capacitor region 14 obtained after calcination is adjusted to be above 200 nm and below 400 nm.

[0056] (Re-oxidation treatment step) In order to return oxygen to the partially reduced barium titanate, which is the main phase, of the dielectric layer 11 after calcination in a reducing atmosphere, heat treatment is sometimes performed at approximately 1000°C in a mixture of N₂ and water vapor, or in an atmosphere at 500°C to 700°C, to a degree that does not oxidize the internal electrode layer 12. This step is called the re-oxidation treatment step.

[0057] (Plating process) Subsequently, Cu, Ni, Sn, and other metals are coated onto the underlying layers of the external electrodes 20a and 20b using a plating process. Through the above steps, the multilayer ceramic capacitor 100 is completed. [Example]

[0058] The following describes the fabrication of a multilayer ceramic capacitor according to an embodiment, and investigates its characteristics.

[0059] (Example 1) Various additives, including ZrO₂, MnCO₃, and Eu oxides, along with organic solvents, were added in specified ratios relative to BaTiO₃ and mixed and pulverized using 0.5 mm zirconia beads. The Zr / Ti atomic concentration ratio was set to 0.04. The Eu / Ti atomic concentration ratio was set to 0.01. The Mn / Ti atomic concentration ratio was set to 0.03. Rare earth elements, except for Eu, were not added. A slurry obtained with the addition of a binder was used to coat the dielectric preform, and Ni paste was used to print the internal electrode pattern. The preform was then laminated and cut into 1005 shapes to create a 1005-shaped ceramic laminate. The ceramic laminate was calcined at a high-speed rate of 6000℃ / h to 1230℃. To reduce oxygen defects generated during reduction calcination, the calcined ceramic laminate was re-oxidized at 1000℃ in a nitrogen atmosphere.

[0060] The thickness of the dielectric layer after calcination is 2.0 μm. Regarding the thickness of the dielectric layer, it was polished using a polishing machine to expose the cross-section shown in Figure 6. The image of the cross-section was taken using a SEM (Scanning Electron Microscope). The length of each of the 20 locations in each of the 5 different fields of view was measured. The average value of the total 100 locations was taken as the thickness of the dielectric layer.

[0061] Figure 6 is a SEM image of the stacked cross-section of the dielectric layer 11 and the internal electrode layer 12 in the capacitor region. As shown in Figure 6, the grain size in the dielectric layer 11 of the capacitor region is approximately uniform. This is believed to be because the abnormal grain growth is suppressed by setting the Zr / Ti atomic concentration ratio to between 0.02 and 0.10. The median grain size in the dielectric layer 11 of the capacitor region is 200 nm. Regarding the median grain size, similar to the thickness of the dielectric layer, the cross-section shown in Figure 6 was exposed using a polishing machine. Using images of this cross-section obtained by SEM, the lengths of 100 particles in each of five different fields of view were measured, and the median grain size was derived from a total of 500 data points.

[0062] Figure 7 shows a TEM (Transmission Electron Microscope) image of the dielectric layer in the capacitor region. As shown in Figure 7, a core portion 31 and a shell portion 32 covering the core portion 31 were identified in the dielectric layer of the capacitor region after calcination. Figure 8(a) shows the TEM-EDS (Energy Dispersive X-ray Spectroscopy) analysis results for the shell portion 32. Figure 8(b) shows the TEM-EDS analysis results for the core portion 31. As shown in Figures 8(a) and 8(b), the Zr concentration in the shell portion 32 is higher than that in the core portion 31. Furthermore, Eu was also identified in the core portion 31.

[0063] The X8R characteristics were measured at 1 kHz and 0.5 Vrms within a range from -55°C to 150°C. The dielectric constant was calculated based on the capacitance at 25°C, the thickness of the dielectric material, and the electrode area. Accelerated life testing was conducted at 170°C and 125 V until all 20 samples failed, and the average time was taken as the lifetime value. Table 1 shows the dielectric constant, accelerated life test results, and X8R characteristic evaluation results. Regarding the relative dielectric constant ε, values ​​above 1500 were considered acceptable "〇", and values ​​below 1500 were considered unacceptable "×". Regarding accelerated life, values ​​above 3000 min were considered acceptable "〇", and values ​​below 3000 min were considered unacceptable "×". Regarding temperature characteristics, conditions meeting the X8R characteristics were considered acceptable "〇", and conditions not meeting the X8R characteristics were considered unacceptable "×". If all three items are qualified, the overall judgment will be set to qualified "〇"; if even one item is unqualified, the overall judgment will be set to unqualified "×".

[0064] Regarding Example 1, it was determined to be qualified "0" based on comprehensive evaluation. The reason for this is that: at least any grain of the dielectric layer in the capacitor region has a core-shell structure, which has a core mainly composed of barium titanate and an outer shell mainly composed of barium titanate with a higher Zr concentration than the core. In the dielectric layer of the capacitor region, the Zr / Ti atomic concentration ratio is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, and the Mn / Ti atomic concentration ratio is 0.005 to 0.05. Compared with the atomic concentration of Eu, the total atomic concentration of other rare earth elements is small. The median grain size of the grains in the dielectric layer of the capacitor region is 200 nm to 400 nm, thereby achieving both high lifetime and excellent capacitor temperature characteristics.

[0065] (Comparative Example 1) In Comparative Example 1, Yb was used instead of Eu. Other conditions were set to be the same as in Example 1.

[0066] (Comparative Example 2) In Comparative Example 2, Ho was used instead of Eu. Other conditions were set to be the same as in Example 1.

[0067] (Comparative Example 3) In Comparative Example 3, Dy was used instead of Eu. Other conditions were set to be the same as in Example 1.

[0068] (Comparative Example 4) In Comparative Example 4, Tb was used instead of Eu. Other conditions were set to be the same as in Example 1.

[0069] (Comparative Example 5) In Comparative Example 5, Gd was used instead of Eu. Other conditions were set to be the same as in Example 1.

[0070] (Comparative Example 6) In Comparative Example 6, Nd was used instead of Eu. Other conditions were set to be the same as in Example 1.

[0071] (Comparative Example 7) In Comparative Example 7, Pr was used instead of Eu. Other conditions were set to be the same as in Example 1.

[0072] (Comparative Example 8) In Comparative Example 8, Ce was used instead of Eu. Other conditions were set to be the same as in Example 1.

[0073] (Comparative Example 9) In Comparative Example 9, La was used instead of Eu. Other conditions were set to be the same as in Example 1.

[0074] Regarding Comparative Examples 1-9, the relative permittivity, accelerated lifetime, and X8R characteristics were measured and comprehensively evaluated in the same manner as in Example 1. In Comparative Examples 1-9, the accelerated lifetime was deemed unqualified. This was attributed to the use of rare earth elements other than Eu. Furthermore, in Comparative Examples 2-9, the X8R characteristics were not met. This was also attributed to the use of rare earth elements other than Eu.

[0075] (Comparative Example 10) In Comparative Example 10, the median grain size of the grains in the dielectric layer of the capacitor region was set to 100 nm by adjusting the calcination conditions, etc. Other conditions were set to be the same as in Example 1.

[0076] (Example 2) In Example 2, the median grain size of the grains in the dielectric layer of the capacitor region was set to 300 nm by adjusting the calcination conditions, etc. Other conditions were set to be the same as in Example 1.

[0077] (Example 3) In Example 3, the median grain size of the grains in the dielectric layer of the capacitor region was set to 400 nm by adjusting the calcination conditions, etc. Other conditions were set to be the same as in Example 1.

[0078] (Comparative Example 11) In Comparative Example 11, the median grain size of the grains in the dielectric layer of the capacitor region was set to 500 nm by adjusting the calcination conditions, etc. Other conditions were set to be the same as in Example 1.

[0079] Regarding Examples 2 and 3 and Comparative Examples 10 and 11, the relative permittivity, accelerated lifetime, and X8R characteristics were measured and comprehensively evaluated in the same manner as in Example 1. In Examples 2 and 3, the comprehensive evaluation was deemed satisfactory "0". The reason for this is that at least one grain of the dielectric layer in the capacitor region has a core-shell structure, which has a core mainly composed of barium titanate and an outer shell mainly composed of barium titanate with a higher Zr concentration than the core. In the dielectric layer of the capacitor region, the Zr / Ti atomic concentration ratio is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, and the Mn / Ti atomic concentration ratio is 0.005 to 0.05. Compared with the Eu atomic concentration, the total atomic concentration of other rare earth elements is small. The median grain size of the grains in the dielectric layer of the capacitor region is 200 nm to 400 nm, thereby achieving both high lifetime and excellent capacitor temperature characteristics. In contrast, in Comparative Examples 10 and 11, the temperature characteristics were unacceptable. The reason is believed to be that the median grain size of the grains in the dielectric layer of the capacitor region was less than 200 nm or more than 400 nm, thereby increasing the rate of change of the capacitor at high temperatures.

[0080] (Comparative Example 12) In Comparative Example 12, the Zr / Ti atomic concentration ratio was set to 0.01. By adjusting the calcination conditions, the median grain size of the grains in the dielectric layer of the capacitor region was set to 800 nm. Other conditions were set to be the same as in Example 1.

[0081] (Example 4) In Example 4, the Zr / Ti atomic concentration ratio was set to 0.02. Other conditions were set to be the same as in Example 1.

[0082] (Example 5) In Example 5, the Zr / Ti atomic concentration ratio was set to 0.06. Other conditions were set to be the same as in Example 1.

[0083] (Example 6) In Example 6, the Zr / Ti atomic concentration ratio was set to 0.08. Other conditions were set to be the same as in Example 1.

[0084] (Example 7) In Example 7, the Zr / Ti atomic concentration ratio was set to 0.10. Other conditions were set to be the same as in Example 1.

[0085] (Comparative Example 13) In Comparative Example 13, the Zr / Ti atomic concentration ratio was set to 0.20. Other conditions were set to be the same as in Example 1.

[0086] Regarding Examples 4-7 and Comparative Examples 12 and 13, the relative permittivity, accelerated lifetime, and X8R characteristics were measured and comprehensively evaluated in the same manner as in Example 1. In Examples 4-7, the comprehensive evaluation was deemed satisfactory "0". The reason for this is that at least one grain of the dielectric layer in the capacitor region has a core-shell structure, which has a core mainly composed of barium titanate and an outer shell mainly composed of barium titanate with a higher Zr concentration than the core. In the dielectric layer of the capacitor region, the Zr / Ti atomic concentration ratio is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, and the Mn / Ti atomic concentration ratio is 0.005 to 0.05. Compared with the Eu atomic concentration, the total atomic concentration of other rare earth elements is small. The median grain size of the grains in the dielectric layer of the capacitor region is 200 nm to 400 nm, thereby achieving both high lifetime and excellent capacitor temperature characteristics. In contrast, in Comparative Example 12, the accelerated lifetime and temperature characteristics were unacceptable. The reason is believed to be that due to the low Zr concentration, the core-shell structure illustrated in Figures 4(a) and 4(b) could not be maintained, resulting in localized abnormal grain growth and thus failing to exhibit the expected lifetime, failing to meet the X8R characteristics. Figure 9 is a SEM image of the stacked cross-section of the dielectric layer 11 and the internal electrode layer 12 in the capacitor region of Comparative Example 12. As shown in Figure 9, abnormal grain growth was confirmed in the dielectric layer of the capacitor region. In Comparative Example 13, the relative permittivity and temperature characteristics were unacceptable. The reason is believed to be that the high Zr concentration led to a decrease in the relative permittivity.

[0087] (Comparative Example 14) In Comparative Example 14, the Eu / Ti atomic concentration ratio was set to 0.0005. Other conditions were set to be the same as in Example 1.

[0088] (Example 8) In Example 8, the Eu / Ti atomic concentration ratio was set to 0.001. Other conditions were set to be the same as in Example 1.

[0089] (Example 9) In Example 9, the Eu / Ti atomic concentration ratio was set to 0.005. Other conditions were set to be the same as in Example 1.

[0090] (Example 10) In Example 10, the Eu / Ti atomic concentration ratio was set to 0.02. Other conditions were set to be the same as in Example 1.

[0091] (Example 11) In Example 11, the Eu / Ti atomic concentration ratio was set to 0.03. Other conditions were set to be the same as in Example 1.

[0092] (Comparative Example 15) In Comparative Example 15, the Eu / Ti atomic concentration ratio was set to 0.04. Other conditions were set to be the same as in Example 1.

[0093] For Examples 8-11 and Comparative Examples 14 and 15, the relative permittivity, accelerated lifetime, and X8R characteristics were measured and comprehensively evaluated in the same manner as in Example 1. In Examples 8-11, the comprehensive evaluation was deemed satisfactory "0". The reason for this is that at least one grain of the dielectric layer in the capacitor region has a core-shell structure, which has a core mainly composed of barium titanate and an outer shell mainly composed of barium titanate with a higher Zr concentration than the core. In the dielectric layer of the capacitor region, the Zr / Ti atomic concentration ratio is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, and the Mn / Ti atomic concentration ratio is 0.005 to 0.05. Compared with the Eu atomic concentration, the total atomic concentration of other rare earth elements is small. The median grain size of the grains in the dielectric layer of the capacitor region is 200 nm to 400 nm, thereby achieving both high lifetime and excellent capacitor temperature characteristics. In contrast, in Comparative Example 14, accelerated lifetime testing failed. The reason is believed to be that the amount of Eu added was too low, failing to achieve sufficiently high lifetime. In Comparative Example 15, accelerated lifetime testing also failed. The reason is believed to be that the amount of Eu added was too high, and semiconductorization prevented the achievement of high lifetime.

[0094] (Comparative Example 16) In Comparative Example 16, the Mn / Ti atomic concentration ratio was set to 0.001. Other conditions were set to be the same as in Example 1.

[0095] (Example 12) In Example 12, the Mn / Ti atomic concentration ratio was set to 0.005. Other conditions were set to be the same as in Example 1.

[0096] (Example 13) In Example 13, the Mn / Ti atomic concentration ratio was set to 0.01. Other conditions were set to be the same as in Example 1.

[0097] (Example 14) In Example 14, the Mn / Ti atomic concentration ratio was set to 0.02. Other conditions were set to be the same as in Example 1.

[0098] (Example 15) In Example 15, the Mn / Ti atomic concentration ratio was set to 0.05. Other conditions were set to be the same as in Example 1.

[0099] (Comparative Example 17) In Comparative Example 17, the Mn / Ti atomic concentration ratio was set to 0.1. Other conditions were set to be the same as in Example 1.

[0100] For Examples 12-15 and Comparative Examples 16 and 17, the relative permittivity, accelerated lifetime, and X8R characteristics were measured and comprehensively evaluated in the same manner as in Example 1. In Examples 12-15, the comprehensive evaluation was deemed satisfactory "0". The reason for this is that at least one grain of the dielectric layer in the capacitor region has a core-shell structure, which has a core mainly composed of barium titanate and an outer shell mainly composed of barium titanate with a higher Zr concentration than the core. In the dielectric layer of the capacitor region, the Zr / Ti atomic concentration ratio is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, and the Mn / Ti atomic concentration ratio is 0.005 to 0.05. Compared with the Eu atomic concentration, the total atomic concentration of other rare earth elements is small. The median grain size of the grains in the dielectric layer of the capacitor region is 200 nm to 400 nm, thereby achieving both high lifetime and excellent capacitor temperature characteristics. In contrast, in Comparative Example 16, the accelerated lifetime was unsatisfactory. The reason for this was believed to be insufficient acceptors and semiconductorization of the dielectric layer. In Comparative Example 17, the accelerated lifetime was also unsatisfactory. The reason for this was believed to be excessive acceptors. [Table 1] BT particle size (nm) Zr / Ti Rare earth elements / Ti Mn / Ti Room temperature relative permittivity life (min) temperature characteristic Comprehensive judgment Example 1 200 0.04 Eu 0.01 0.03 2100 6000 〇 〇 Comparative Example 1 200 0.04 Yb 0.01 0.03 1900 310 〇 × Comparative Example 2 200 0.04 Ho 0.01 0.03 2050 260 × × Comparative Example 3 200 0.04 Dy 0.01 0.03 2070 340 × × Comparative Example 4 200 0.04 Tb 0.01 0.03 2080 250 × × Comparative Example 5 200 0.04 Gd 0.01 0.03 2090 120 × × Comparative Example 6 200 0.04 Nd 0.01 0.03 2150 0 × × Comparative Example 7 200 0.04 Pr 0.01 0.03 2160 0 × × Comparative Example 8 200 0.04 Ce 0.01 0.03 2170 40 × × Comparative Example 9 200 0.04 La 0.01 0.03 2180 70 × × Comparative Example 10 100 0.04 Eu 0.01 0.03 1600 7100 × × Example 2 300 0.04 Eu 0.01 0.03 2350 5500 〇 〇 Example 3 400 0.04 Eu 0.01 0.03 2600 5000 〇 〇 Comparative Example 11 500 0.04 Eu 0.01 0.03 3000 4000 × × Comparative Example 12 200 0.01 Eu 0.01 0.03 4000 0 × × Example 4 200 0.02 Eu 0.01 0.03 2500 4200 〇 〇 Example 5 200 0.06 Eu 0.01 0.03 2300 6200 〇 〇 Example 6 200 0.08 Eu 0.01 0.03 2000 6500 〇 〇 Example 7 200 0.10 Eu 0.01 0.03 1600 7000 〇 〇 Comparative Example 13 200 0.20 Eu 0.01 0.03 1000 7300 × × Comparative Example 14 200 0.04 Eu 0.0005 0.03 1800 500 〇 × Example 8 200 0.04 Eu 0.001 0.03 1900 3000 〇 〇 Example 9 200 0.04 Eu 0.005 0.03 2000 4000 〇 〇 Example 10 200 0.04 Eu 0.02 0.03 2300 6500 〇 〇 Example 11 200 0.04 Eu 0.03 0.03 2400 7500 〇 〇 Comparative Example 15 200 0.04 Eu 0.04 0.03 0 0 × × Comparative Example 16 200 0.04 Eu 0.01 0.001 0 0 × × Example 12 200 0.04 Eu 0.01 0.005 2400 3000 〇 〇 Example 13 200 0.04 Eu 0.01 0.01 2350 4000 〇 〇 Example 14 200 0.04 Eu 0.01 0.02 2250 5500 〇 〇 Example 15 200 0.04 Eu 0.01 0.05 2000 3000 〇 〇 Comparative Example 17 200 0.04 Eu 0.01 0.1 1800 500 × × Comparative Example 18 200 0.04 Eu / Dy 0.01 / 0.01 0.03 2100 1100 × × Example 16 400 0.02 Eu 0.01 0.05 3000 4000 〇 〇 Example 17 200 0.10 Eu 0.03 0.05 1700 5500 〇 〇

[0101] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to specific embodiments, and various changes and modifications can be made within the scope of the spirit of the present invention as described in the claims.

[0102] 10: Stacked wafers 11: Dielectric layer 12: Internal electrode layer 13: Overlay 14: Capacitor Area 15: End edge 16: Side edge 17: Grains 20a: External electrode 20b: External electrode 30: Core-shell particles 31: Core Department 32: Outer shell 100: Multilayer ceramic capacitor

Claims

1. A dielectric material, characterized in that: it comprises a plurality of grains mainly composed of barium titanate, and contains Zr, Eu, and Mn as additives; at least any one of the plurality of grains has a core-shell structure, the core-shell structure comprising a core mainly composed of barium titanate and an outer shell mainly composed of barium titanate with a Zr concentration higher than that of the core; the Zr / Ti atomic concentration ratio of the dielectric material is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, the Mn / Ti atomic concentration ratio is 0.005 to 0.05, and the total atomic concentration of other rare earth elements is smaller than that of Eu; the median grain size of the plurality of grains is 200 nm to 400 nm.

2. The dielectric of claim 1, wherein the rare earth element contained in the plurality of grains as the additive is only Eu.

3. A multilayer ceramic capacitor, characterized in that it comprises a multilayer structure formed in such a way that dielectric layers and internal electrode layers are alternately stacked, and a plurality of the stacked internal electrode layers are alternately exposed on two different surfaces; the dielectric layer in the capacitor region where the internal electrode layers exposed on the two different surfaces face each other comprises a plurality of grains mainly composed of barium titanate, and contains Zr, Eu, and Mn as additives; at least one of the plurality of grains has a core-shell structure, the core-shell structure comprising a core mainly composed of barium titanate and a shell mainly composed of barium titanate with a Zr concentration higher than that of the core; the Zr / Ti atomic concentration ratio of the dielectric layer is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, and the Mn / Ti atomic concentration ratio is 0.005 to 0.05; and the total atomic concentration of other rare earth elements is smaller than that of Eu. The median grain size of the aforementioned plurality of grains is between 200 nm and 400 nm.

4. The multilayer ceramic capacitor, as requested in item 3, satisfies the X8R characteristic.

5. A method for manufacturing a dielectric, characterized in that: a dielectric blank is heated at a heating rate of 5000℃ / h to 10000℃ / h and calcined to obtain a dielectric comprising a plurality of grains mainly composed of barium titanate, wherein the median particle size of the plurality of grains is 200 nm to 400 nm, wherein the dielectric blank comprises barium titanate powder and contains Zr, Eu and Mn as additives, wherein the Zr / Ti atomic concentration ratio is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, and the Mn / Ti atomic concentration ratio is 0.005 to 0.05, and the total atomic concentration of other rare earth elements is smaller than that of Eu.

6. A method for manufacturing a multilayer ceramic capacitor, characterized by: a step of multiplying multiple multilayer units printed with metal conductive paste on a dielectric blank to obtain a ceramic multilayer body, wherein the dielectric blank contains barium titanate powder and contains Zr, Eu and Mn as additives, the Zr / Ti atomic concentration ratio is 0.02 to 0.10, the Eu / Ti atomic concentration ratio is 0.001 to 0.03, the Mn / Ti atomic concentration ratio is 0.005 to 0.05, and the total atomic concentration of other rare earth elements is smaller than that of Eu; and the ceramic multilayer body is calcined by heating at a heating rate of 5000°C / h to 10000°C / h to form a dielectric layer containing a plurality of grains mainly composed of barium titanate, wherein the median grain size of the plurality of grains is 200 nm to 400 nm.

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