Multilayer ceramic electronic components and dielectric ceramic compositions

Abstract

The present invention provides multilayer ceramic electronic components and dielectric ceramic compositions that suppress changes in capacitance due to firing temperature and have high reliability. [Solution] The multilayer ceramic electronic component has a perovskite structure represented by the general formula ABO3, and comprises a dielectric layer 11 having a first crystal grain 41 having a core portion 411 containing molybdenum and a shell portion 412 covering the core portion 411 and containing rare earth elements and manganese, and a second crystal grain 42 mainly composed of barium titanate with an elemental ratio of barium to titanium of 0.70 or less, a plurality of internal electrode layers 12 facing each other across the dielectric layer 11, and external electrodes 20a, 20b electrically connected to the internal electrode layers 12.

Description

[Technical Field]

[0001] This invention relates to multilayer ceramic electronic components and dielectric ceramic compositions. [Background technology]

[0002] Multilayer ceramic electronic components, such as multilayer ceramic capacitors (MLCCs), are used in high-frequency communication systems, including those found in mobile phones. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2002-087879 [Overview of the project] [Problems that the invention aims to solve]

[0004] In recent years, the use of multilayer ceramic electronic components has expanded to include electronic circuits that affect human life, such as in-vehicle electronic control systems. This demands high reliability while simultaneously requiring greater mass production capabilities from a supply perspective.

[0005] Dielectric ceramic compositions used in the dielectric layers of multilayer ceramic electronic components utilize a core-shell structure in which barium titanate forms the core, surrounded by a shell containing various additives in solid solution. This structure allows for the transition of high capacitance near the Curie temperature (around 125°C), where barium titanate transitions from a ferroelectric to a paraelectric phase, to lower temperatures in the shell due to the effects of the various additives. Therefore, it is possible to design components with higher capacitance in the practical temperature range around room temperature.

[0006] The core-shell structure is considered to be formed by dissolving various additives in barium titanate. The core-shell structure is considered to be formed, for example, in a firing temperature range of 1000°C to 1400°C, by the reaction of components added as various additives with barium titanate particles as the main component. Generally, as the firing temperature increases, various additives dissolve and the shell part becomes thicker. Therefore, in order to keep the capacitance of the multilayer ceramic electronic component within the required range, it is necessary to precisely control the solid solution of various additives.

[0007] For example, Patent Document 1 discloses a dielectric ceramic composition, a dielectric material, and a multilayer ceramic capacitor containing a barium titanate-based main component and a subcomponent, in which the relative intensity of a pyrochlore phase containing a rare earth element is controlled in XRD analysis after sintering.

[0008] In recent years, due to the expanding use of dielectric ceramic compositions and multilayer ceramic electronic components, higher mass productivity has been demanded. Therefore, it is necessary to suppress the change in capacitance due to the firing temperature and reduce the fluctuation of capacitance due to temperature.

[0009] The present invention has been made in view of the above problems, and an object thereof is to provide a multilayer ceramic electronic component and a dielectric ceramic composition that suppress the change in capacitance due to the firing temperature and have high reliability.

Means for Solving the Problems

[0010] The multilayer ceramic electronic component according to the present invention has a perovskite structure represented by the general formula ABO3, and has a first crystal particle having a core part containing molybdenum and a shell part covering the core part and containing a rare earth element and manganese, and a dielectric layer having a second crystal particle having barium titanate as a main component and an elemental ratio of barium to titanium of 0.70 or less, a plurality of internal electrodes facing each other with the dielectric layer interposed therebetween, and an external electrode electrically connected to the internal electrodes.

[0011] In the above multilayer ceramic electronic component, barium is included in the A site of the perovskite structure, and the element included in the B site of the perovskite structure may include at least one of titanium or zirconium.

[0012] In the above multilayer ceramic electronic component, the rare earth element may be at least one selected from lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, ytterbium.

[0013] In the above multilayer ceramic electronic component, the element ratio of molybdenum to titanium in the first crystal particles may be 0.001 or more.

[0014] In the above multilayer ceramic electronic component, the element ratio of molybdenum to titanium in the second crystal particles may be less than 0.01

[0015] In the above multilayer ceramic electronic component, the second crystal particles are BaTi4O9, BaTi5O

[0018] , 、BaTi6O 13 、Ba4Ti 11 O 26 、Ba4Ti 12 O 27 、Ba4Ti 13 O 30 、or Ba6Ti 17 O 40 and may include at least one selected from.

[0016] In the above multilayer ceramic electronic component, the maximum particle diameter of the first crystal particles may be 2 μm or less.

[0017] In the above multilayer ceramic electronic component, the shell portion may contain magnesium and manganese.

[0018] [[ID=4〕7] The dielectric ceramic composition according to the present invention comprises a first crystalline particle having a perovskite structure represented by the general formula ABO3, and having a core portion containing molybdenum and a shell portion covering the core portion and containing rare earth elements and manganese, and a second crystalline particle mainly composed of barium titanate, in which the elemental ratio of barium to titanium is 0.70 or less. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide multilayer ceramic electronic components and dielectric ceramic compositions that suppress changes in capacitance due to firing temperature and have high reliability. [Brief explanation of the drawing]

[0020] [Figure 1] This figure illustrates a dielectric ceramic composition according to the first embodiment. [Figure 2] This is a diagram illustrating a unit cell. [Figure 3] This diagram illustrates a method for verifying the core-shell structure. [Figure 4] This is a partial cross-sectional perspective view of a multilayer ceramic capacitor. [Figure 5] This is a cross-sectional view along line AA in Figure 5. [Figure 6] Figure 5 is a cross-sectional view along line BB. [Figure 7] This diagram illustrates a flow chart of the manufacturing process for multilayer ceramic capacitors. [Figure 8] (a) and (b) are diagrams illustrating the internal electrode formation process. [Figure 9] This is a diagram illustrating the crimping process. [Figure 10] This diagram illustrates the side margin area. [Modes for carrying out the invention]

[0021] The embodiments will be described below with reference to the drawings.

[0022] (First Embodiment) The dielectric ceramic composition according to the first embodiment is a ceramic polycrystalline material containing crystalline grains having a perovskite structure represented by the general formula ABO3, as illustrated in Figure 1. Of these ceramic polycrystalline materials, at least one is a first crystalline grain 41 having a core-shell structure, and at least one is a second crystalline grain 42 having an elemental ratio of barium to titanium of 0.70 or less. Here, elemental ratio refers to the ratio of the number of elements.

[0023] The first crystal grain 41 comprises a roughly spherical core portion 411 and a shell portion 412 that surrounds and covers the core portion 411. The core portion 411 is a crystalline portion in which the additive elements are not solid-dissolved or the amount of solid-dissolved additive elements is small. The shell portion 412 is a crystalline portion in which the additive elements are solid-dissolved and have a higher concentration of additive elements than the concentration of additive elements in the core portion 411. Therefore, the additive elements solid-dissolved in the core portion 411 are solid-dissolved in the shell portion 412 at a higher elemental concentration than in the core portion 411. The elements solid-dissolved in the shell portion 412 are either not solid-dissolved in the core portion 411 or are solid-dissolved at a lower elemental concentration than in the shell portion 412.

[0024] In this embodiment, the first crystal grain 41 contains molybdenum (Mo) in the core portion 411 and rare earth element R and manganese in the shell portion 412. Furthermore, the dielectric ceramic composition includes second crystal grains 42 in which the elemental ratio of barium to titanium is 0.70 or less. This configuration improves the reliability of the dielectric ceramic composition because the molybdenum, which functions as a donor, is included up to the core portion 411. The inclusion of rare earth element R and manganese in the shell portion 412 suppresses the change in capacitance due to changes in firing temperature, and further suppresses the movement of oxygen vacancies between grain boundaries and within the shell portion 412, thereby further improving reliability. Moreover, the inclusion of second crystal grains 42 in the dielectric ceramic composition, in which the elemental ratio of barium to titanium is 0.70 or less, prevents excessive growth of crystal grains during firing, thereby suppressing the change in capacitance due to changes in firing temperature. From the above, the dielectric ceramic composition according to this embodiment is highly reliable and can suppress changes in capacitance due to firing temperature. Oxygen vacancies are sometimes also called oxide ion vacancies or oxygen ion vacancies.

[0025] The rare earth element R in which the shell portion 412 is solid-dissolved is not particularly limited, but is at least one selected from, for example, lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), and ytterbium (Yb). The elemental concentration of the rare earth element R in the shell portion 412 is greater than the elemental concentration of the rare earth element in the core portion 411.

[0026] For example, when observing a cross-section of a dielectric ceramic composition in a field of view where a total of 100 or more first crystal particles 41 and second crystal particles 42 are observed, the area ratio of the first crystal particles 41 is 95% or more and 99.95% or less, and the area ratio of the second crystal particles 42 is 0.01% or more and 5% or less.

[0027] The perovskite-type crystal grain, which is the main component of the first crystal grain 41, has a unit cell as illustrated in Figure 2. This unit cell contains A sites located at the vertices of the lattice, O sites located at the center of the lattice faces, and B sites located within the octahedron with the O sites as vertices. In the perovskite structure, alkaline earth metals that can accept divalent cations, such as barium (Ba), strontium (Sr), and calcium (Ca), are arranged at the A sites, and metal atoms that can accept tetravalent cations, such as hafnium (Hf), zirconium (Zr), and titanium (Ti), are arranged at the B sites.

[0028] The perovskite structure allows for compositional formulas that deviate from stoichiometric compositions. That is, the ratio of the A-site element to the B-site element does not necessarily have to be 1:1, and defects may be generated as long as they maintain the perovskite structure. Defects may also be generated in the oxygen atom. For example, compositional formula A α BO 3-β In this case, compositions in the range of 0.98 ≤ α ≤ 1.01 and 0 ≤ β ≤ 0.20 are permissible.

[0029] However, the formation of oxygen vacancies, for example, can reduce resistivity or cause ionic conductivity, leading to a decrease in electrical lifespan or increased dielectric loss when used as a multilayer ceramic capacitor, making it impractical in some cases. Therefore, by solid-solving molybdenum in the first crystal grains 41 having a perovskite structure, the electrical lifespan can be effectively increased. In particular, in this embodiment, the inclusion of molybdenum in the core portion 411 effectively increases the electrical lifespan. To fully obtain the effect of molybdenum, it is preferable that the elemental ratio of molybdenum to titanium in the entire first crystal grains 41 be 0.001 or higher.

[0030] Furthermore, the first crystal grain 41 may optionally contain at least one of the second transition elements: yttrium (Y), zirconium (Zr), niobium (Nb), ruthenium (Ru), rhodium (Rh), palladium (Pd), and silver (Ag). This makes it possible to improve resistivity, increase electrical lifetime, and reduce dielectric loss relative to capacitance.

[0031] Furthermore, the first crystal grain 41 may optionally contain at least one of the following third transition elements: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), and gold (Au). This makes it possible to improve resistivity, increase electrical lifetime, and reduce dielectric loss relative to capacitance.

[0032] It is preferable that the dielectric ceramic composition contains additives that include rare earth elements R, such as lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), and ytterbium (Yb). It is also preferable that the dielectric ceramic composition contains titanium-containing additives such that the elemental ratio (ratio of the number of elements) of titanium to the rare earth elements R is 1 or more. Compared to cases where titanium-containing additives are not added, the solid solution reaction with barium titanate crystal particles is relatively suppressed. This effect makes it possible to achieve firing in a shorter time while suppressing the rate of change in capacitance due to changes in firing temperature, thereby enabling high mass production.

[0033] Preferred additives containing the rare earth element R mentioned above include lanthanum oxide (La2O3), cerium oxide (Ce2O3), praseodymium oxide (Pr2O3), neodymium oxide (Nd2O3), promethium oxide (Pm2O3), samarium oxide (Sm2O3), europium oxide (Eu2O3), gadolinium oxide (Gd2O3), terbium oxide (Tb2O3), dysprosium oxide (Dy2O3), holmium oxide (Ho2O3), erbium oxide (Er2O3), and ytterbium oxide (Yb2O3).

[0034] As for the titanium-containing additives mentioned above, titanium dioxide is a preferred example, but titanium hydroxide (Ti(OH)4), titanium chloride (TiCl4), titanium carbide (TiC), titanium sulfide (TiS2), etc., can also be used.

[0035] Additionally, additives containing rare earth elements R and titanium, such as La2Ti2O7, Ce2Ti2O7, Pr2Ti2O7, Nd2Ti2O7, Pm2Ti2O7, Sm2Ti2O7, Eu2Ti2O7, Gd2Ti2O7, Tb2Ti2O7, Dy2Ti2O7, Ho2Ti2O7, Er2Ti2O7, and Yb2Ti2O7, can also be used.

[0036] In dielectric ceramic compositions, in addition to the addition of rare earth elements R, it is preferable to add 0.2 mol or more and 5.0 mol or less of manganese oxide (MnO) per 100 mol of barium titanate, such that the Mn / Ti elemental ratio z, which is the ratio of manganese elements to titanium content, is 0.002 ≤ z ≤ 0.05.

[0037] Incidentally, in a core-shell structure, as the firing temperature generally increases, various additives tend to dissolve more in the barium titanate crystal grains, causing the shell to thicken. In the shell, the large capacitance range around 125°C, which is near the Curie temperature of barium titanate, approaches room temperature. As a result, the capacitance in the practical temperature range around room temperature changes significantly depending on the thickness of the shell. Therefore, as an example, in order to keep the capacitance of a multilayer ceramic capacitor within the required range, it is preferable to precisely control the firing temperature.

[0038] For example, the dielectric ceramic composition according to this embodiment can be obtained by maintaining a temperature of 900°C to 1100°C, then firing it at 1150°C to 1300°C, and by rapidly increasing the heating rate during the firing process from 3000°C / h to 10000°C / h.

[0039] The first crystal grain 41, which has a core-shell structure in which a shell portion 412 containing a rare earth element R is formed, has a different formation process than conventional core-shell structures. Specifically, in addition to solid solution of the rare earth element R into the crystal grain made of barium titanate, the added rare earth element R and titanium first form compounds such as R2Ti2O7, which have a pyrochlore structure or perovskite slab structure, and then react with the surface of the barium titanate crystal grain to form the shell portion 412 in the form of a composite perovskite compound such as R(Ti,Mn)O3. Therefore, excessive solid solution reactions of the rare earth element R into the shell portion 412 can be suppressed, and the rate of change in capacitance due to changes in firing temperature can be suppressed. As a trace of this shell portion 412 formation process, an oxide region with a higher concentration of the rare earth element R than the shell portion is formed. The formation reaction of R2Ti2O7 takes place between 900°C and 1100°C.

[0040] To promote this shell formation reaction, it is desirable that the rare earth element R is an element that readily dissolves in the A site of ABO3. Specifically, it is preferable that the rare earth element R has a larger ionic radius than erbium (Er) and is one of the following: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), or holmium (Ho).

[0041] On the other hand, using rare earth elements R (erbium, thulium, ytterbium, ruthenium) with ionic radii smaller than holmium produces the pyrochlore compound R2Ti2O7. However, the shell formation reaction between R2Ti2O7 and barium titanate crystal particles does not proceed sufficiently, and there is a risk that the core and oxide regions of multiple particles will come into electrical contact. As a result, the resistivity decreases, which may make it unsuitable for use in multilayer ceramic capacitors.

[0042] In the shell portion 412, the added magnesium may react on the surface of the barium titanate crystal particles to form the shell portion of a complex perovskite compound such as R(Mg,Ti,Mn)O3.

[0043] Furthermore, the composite perovskite compound, which is thought to be R(Ti,Mn)O3 or R(Mg,Ti,Mn)O3, may be formed as the shell portion 412 as (R,Ba)(Ti,Mn)O3 or (R,Ba)(Mg,Ti,Mn)O3 by reaction with the surrounding main component, barium titanate crystal particles.

[0044] For example, the core portion 411 in the core-shell structure mainly consists of crystalline grains made of barium titanate, but may also contain added rare earth elements R, manganese, magnesium, etc. However, it is sufficient if, for example, the shell portion 412 contains a relatively larger amount of the added rare earth elements R, manganese, magnesium, etc. than the core portion 411.

[0045] More specifically, crystal grains having a core-shell structure, with barium titanate as the main component and a shell containing rare earth elements and manganese, only need to contain a relatively high amount of these elements at any point within the range where the distance from the surface towards the center is 10% of the diameter of the crystal grain, compared to the elemental ratio of rare earth elements or manganese to titanium in the center. The presence of such core-shell crystal grains not only suppresses the range of change in capacitance due to changes in firing temperature, but also suppresses the movement of oxygen vacancies within grain boundaries and the shell, thereby suppressing the decrease in resistivity and improving the electrical lifetime of the polycrystalline material constituting the dielectric ceramic composition.

[0046] Furthermore, the average particle size of the first crystalline particles 41 in the dielectric ceramic composition is within the range of 50 nm to 500 nm, and large particles of 3 μm or more are not retained in the parts that are electrically utilized as a dielectric. For example, in the dielectric ceramic composition, it is preferable that the maximum particle size of the first crystalline particles 41 is 2 μm or less. And, considering the general characteristics of ceramics, where the particle size and composition distribution of the contained crystalline particles fall within a relatively narrow range, if it can be confirmed that the first crystalline particles 41 have a core-shell structure, then the presence of a large number of first crystalline particles 41 with similar structures can be said to have a positive effect on the electrical lifetime of the electromagnetic induction composition.

[0047] The particle size of the first crystal grains 41 can be measured by the following procedure. The dielectric ceramic composition having the first crystal grains 41 is cut or polished to expose the observation surface. This exposure method is not particularly limited, and methods such as cutting or polishing the element can be used. At this time, in order to observe the internal ceramic structure sufficiently, it is preferable to use a diamond paste of 2 μm or less to obtain a smooth surface that can be judged as a mirror surface. Next, a conductive material such as platinum or osmium is deposited on the observation surface, and then it is observed with a scanning electron microscope (SEM) to take a photograph of the first crystal grains 41. Next, several parallel lines are drawn in the photograph, and the length of the line segment cut off at the periphery of each first crystal grain 41 (the distance between the two points where each line intersects the periphery of the first crystal grain 41) is taken as the particle size (grain size) of the first crystal grains 41. In this method, the particle size of the first crystal grains 41 is measured for 400 or more particles, and the average of the obtained results is taken as the average particle size of the first crystal grains 41. Furthermore, if the outline of the first crystal grains 41 is difficult to see in the exposed ceramics, it is advisable to perform a heat treatment (thermal etching) on ​​the exposed ceramics for about 5 minutes at a temperature about 50°C lower than the firing temperature, prior to the deposition of platinum or osmium. Alternatively, chemical etching can be performed using hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, or mixtures thereof, at an appropriate concentration for etching.

[0048] The presence of a first crystalline particle 41 with a core-shell structure in the dielectric ceramic composition can be confirmed by the following procedure. Note that the following procedure describes the case where gadolinium is used as the rare earth element, as an example.

[0049] First, a sample for transmission electron microscopy (TEM) observation is cut from the dielectric ceramic composition to be examined. This cutting can be done using a focused ion beam (FIB) device or similar.

[0050] Next, the sample cut out for TEM observation is observed using a TEM equipped with an energy-dispersive X-ray spectrometer (EDS) or a wavelength-dispersive X-ray spectrometer (WDS) to determine the crystal grains to be measured and to identify the outer periphery shape of those grains.

[0051] Next, as illustrated in Figure 3, determine the longest line segment connecting any two points on the outer circumference of the crystal grain to be measured, and measure the length L of that segment. This length L is then taken as the diameter of the crystal grain to be measured. Furthermore, determine the midpoint M of the line segment from the obtained length.

[0052] For any point C on the outer circumference of the above line segment, within a range of 10% of the crystal grain diameter from both ends, compositional analysis is performed by EDS or WDS to calculate the elemental abundance ratio of the element being analyzed to titanium. In compositional analysis, for example, in EDS measurement, the titanium K-line intensity is simply determined relative to the barium K-line or L-line, the gadolinium L-line, the manganese K-line, and the molybdenum K-line. More specifically, corrections (ZAF correction) are performed on these intensities, taking into account atomic number effects, absorption effects, and fluorescence excitation effects, to calculate the ratio of each element to the titanium element content, and this is taken as the ratio of each element to titanium in the shell portion 412. Similarly, compositional analysis is performed on the midpoint M of the above line segment to calculate the ratio, and this is taken as the ratio of each element to titanium in the core portion 411.

[0053] Next, the ratio of each element to titanium in the shell portion 412 is compared with the ratio of each element to titanium in the core portion 411. Since the ratio of each element to titanium in the shell portion 412 is higher than that in the core portion 411, it is determined that the first crystal grain 41 being measured has a core-shell structure.

[0054] As described above, the dielectric ceramic composition, in addition to the first crystal particles 41, holds at least one crystal particle as a second crystal particle 42 other than the first crystal particles 41, which is made of a barium titanate-based composite oxide in which the elemental ratio of barium to titanium is 0.70 or less.

[0055] In the second crystal grain 42, the elemental ratio of barium to titanium is preferably 0.16 or higher. The second crystal grain 42 may also contain manganese. The elemental ratio of manganese to titanium in the second crystal grain may be 0.02 or more and 0.10 or less, or 0.02 or more and 0.05 or less.

[0056] A more preferred example of the second crystal grain 42 is Ba4Ti 11 O 26 Preferably, the barium titanate composite oxide is monoclinic, has a space group C2 / m, and has lattice constants a=15.160 Å, b=3.893 Å, c=9.093 Å, and β=98.6°. This is because the ratio of barium to titanium in this barium titanate composite oxide is relatively close to 3, and it is easy to intentionally precipitate it without using a large amount of titanium-based additives.

[0057] A more preferred example of the second crystal grain 42 is Ba4Ti 11 O 26 In contrast, it is desirable that magnesium, manganese, and nickel are dissolved in solid solution and occupy the defect sites, or that some of the titanium is replaced. Ba4Ti 11 O 26 This material has a crystal structure in which defects occur at some of the titanium sites. Therefore, at the defect locations, titanium is more likely to change from a tetravalent cation to a trivalent cation, resulting in a decrease in resistivity. To compensate for this, it is effective to have at least one of magnesium, manganese, or nickel in solid solution.

[0058] A more preferred example of the second crystal grain 42 is Ba4Ti 11 O 26In contrast, it is preferable to have less solid solution of molybdenum. Since molybdenum ions tend to be stable in tetravalent to hexavalent states, Ba4Ti 11 O 26 When titanium is dissolved in solid solution, it readily changes from a tetravalent cation to a trivalent cation, resulting in a decrease in resistivity. For example, in the second crystal grain 42, the elemental ratio of molybdenum to titanium is preferably less than 0.01.

[0059] The second crystal grain 42, as is evident from its compositional formula, is a barium titanate composite oxide with a lower elemental ratio of barium than titanium. It is a by-product of the shell formation process described above, when titanium-based additives are used as additives. Other examples of the second crystal grain 42 include BaTi4O9 and BaTi5O9. 11 BaLi6O 13 Ba4Ru 11 O 26 Ba4Ru 12 O 27 Ba4Ru 13 O 30 , or Ba6Ti 17 O 40 Examples include at least one selected from the following.

[0060] The presence of the second crystalline particle 42 in the dielectric ceramic composition can be confirmed by the following procedure.

[0061] First, the diffraction line profile of the dielectric ceramic composition to be examined, or the powder obtained by grinding the dielectric ceramic composition, is measured using an X-ray diffractometer (XRD) that uses Cu-Kα rays. The grinding method for obtaining the powder is not particularly limited, and a hand mill (mortar and pestle) can be used. When measuring the diffraction line profile of the ceramics constituting a multilayer ceramic capacitor, the electrodes and coatings formed on the surface of the element, and parts other than the dielectric layer of the multilayer ceramic capacitor, are removed to expose the surface of the dielectric ceramic composition. This exposure method is not particularly limited, and methods such as cutting or polishing the element can be employed. Furthermore, when measuring the diffraction line profile of the powder of the dielectric ceramic composition constituting a multilayer ceramic capacitor, it is more preferable to grind it after removing the electrodes and coatings formed on the element, and parts other than the dielectric layer of the multilayer ceramic capacitor.

[0062] Next, in the obtained diffraction profile, the percentage of the strongest diffraction line intensity in the diffraction profile derived from other structures is calculated relative to the strongest diffraction line intensity in the profile derived from the perovskite structure. If this percentage is 10% or less, it is determined that the dielectric ceramic composition under investigation is composed of first crystalline particles 41 having a perovskite structure. Note that when the surface of the dielectric ceramic composition of a multilayer ceramic capacitor is exposed using the above method, or when XRD measurements are performed on the pulverized powder, peaks of materials constituting the electrodes and coatings may also be detected. In such cases, these should be excluded before calculating the diffraction line intensity percentage as described above.

[0063] Next, we will focus on peaks other than diffraction line intensity in the profile derived from the perovskite structure to identify the crystalline phase. Ideally, the crystalline phase should be identified by searching the PDF (Powder Diffraction File) published by ICDD (International Centre for Diffraction Data; Pennsylvania, USA) to check for the presence of the second crystalline grain 42. Ba4Ti is a suitable example. 11 O26 In this case, the generation can be evaluated by identifying it by referring to PDF-01-083-1459.

[0064] Next, it can be confirmed that the second crystal grain 42 is made of a barium titanate composite oxide in which the elemental ratio of barium to titanium is 0.70 or less and the elemental ratio of molybdenum to titanium is 0.01 or less, using the same method as the one used to confirm the existence of the first crystal grain 41 having the core-shell structure described above.

[0065] Furthermore, as illustrated in Figure 1, the dielectric ceramic composition may contain crystal particles 43 having a different composition or crystal structure from the first crystal particles 41 and the second crystal particles 42. The dielectric ceramic composition may also contain silicon-containing crystal particles or glass particles. This makes it possible to sufficiently densify the dielectric ceramic composition by firing it at 1300°C or below.

[0066] Examples of crystalline grains 43 include silicates (SiO2), enstatates (MgSiO3), barium magnesium silicate (BaMgSiO4), and fresnoite (Ba2TiSi2O8), as well as glass grains.

[0067] Other examples of crystalline particles 43 include gakeylite (MgTiO3), manganese nickel oxide ((Mn,Ni)O), pyrophanite (MnTiO3), and by-compounds arising from added materials or from the electrodes.

[0068] (Second Embodiment) In the second embodiment, a multilayer ceramic capacitor 100 using the dielectric ceramic composition according to the first embodiment will be described.

[0069] Figure 4 is a partial cross-sectional perspective view of the multilayer ceramic capacitor 100. Figure 5 is a cross-sectional view taken along line AA in Figure 4. Figure 6 is a cross-sectional view taken along line BB in Figure 4. As illustrated in Figures 4 to 6, the multilayer ceramic capacitor 100 comprises a stacked chip 10 having a substantially rectangular parallelepiped shape and external electrodes 20a and 20b provided on two opposing end faces of either the stacked chip 10. Of the four faces of the stacked chip 10 other than the two end faces, the two faces other than the top and bottom faces in the stacking direction are referred to as side faces. The external electrodes 20a and 20b extend to the top, bottom, and two side faces of the stacked chip 10 in the stacking direction. However, the external electrodes 20a and 20b are spaced apart from each other.

[0070] The multilayer chip 10 has a structure in which dielectric layers 11 containing a dielectric ceramic composition and internal electrode layers 12 containing a base metal material are alternately stacked. The edges of each internal electrode layer 12 are alternately exposed to the end face of the multilayer chip 10 where the external electrode 20a is provided and the end face where the external electrode 20b is provided. As a result, each internal electrode layer 12 is alternately electrically connected to the external electrode 20a and the external electrode 20b. Consequently, the multilayer ceramic capacitor 100 has a structure in which multiple dielectric layers 11 are stacked via internal electrode layers 12. Furthermore, in the laminate of dielectric layers 11 and internal electrode layers 12, the outermost layer in the stacking direction is an internal electrode layer 12, and the top and bottom surfaces of the laminate are covered by a cover layer 13. The cover layer 13 is mainly composed of a ceramic material. For example, the main components of the cover layer 13 are the same as those of the dielectric layer 11 and the ceramic material.

[0071] The dimensions of the multilayer ceramic capacitor 100 are, for example, 0.25 mm in length, 0.125 mm in width, and 0.125 mm in height, or 0.4 mm in length, 0.2 mm in width, and 0.2 mm in height, or 0.6 mm in length, 0.3 mm in width, and 0.3 mm in height, or 1.0 mm in length, 0.5 mm in width, and 0.5 mm in height, or 3.2 mm in length, 1.6 mm in width, and 1.6 mm in height, or 4.5 mm in length, 3.2 mm in width, and 2.5 mm in height, but are not limited to these dimensions.

[0072] The internal electrode layer 12 mainly consists of base metals such as nickel (Ni), copper (Cu), and tin (Sn). Precious metals such as platinum (Pt), palladium (Pd), silver (Ag), and gold (Au), or alloys containing these, may also be used as the internal electrode layer 12.

[0073] As illustrated in Figure 5, the region where the internal electrode layer 12 connected to the external electrode 20a and the internal electrode layer 12 connected to the external electrode 20b face each other is a region in the multilayer ceramic capacitor 100 where capacitance is generated. Therefore, this region where capacitance is generated is referred to as the capacitance region 14. In other words, the capacitance region 14 is the region where adjacent internal electrode layers 12 connected to different external electrodes face each other.

[0074] The region where internal electrode layers 12 connected to external electrode 20a face each other without being connected to an internal electrode layer 12 connected to external electrode 20b is called the end margin 15. Similarly, the region where internal electrode layers 12 connected to external electrode 20b face each other without being connected to an internal electrode layer 12 connected to external electrode 20a is also called the end margin 15. In other words, the end margin 15 is the region where internal electrode layers 12 connected to the same external electrode face each other without being connected to an internal electrode layer 12 connected to a different external electrode. The end margin 15 is a region where no capacitance is generated.

[0075] As illustrated in Figure 5, in the stacked chip 10, the region extending from the two sides of the stacked chip 10 to the internal electrode layer 12 is called the side margin 16. That is, the side margin 16 is a region provided to cover the ends of the multiple internal electrode layers 12 stacked in the stacked structure that extend to the two sides. The side margin 16 is also a region that does not generate electrical capacitance.

[0076] In the multilayer ceramic capacitor 100 according to this embodiment, at least a portion of the dielectric layer 11 in the capacitance region 14 contains the first crystal particles 41 illustrated in Figure 1, as well as the second crystal particles 42. This suppresses changes in capacitance due to firing temperature and enables high insulation performance in a wide firing atmosphere. As a result, high mass production efficiency can be achieved. Furthermore, high reliability can be obtained.

[0077] Next, the manufacturing method of the multilayer ceramic capacitor 100 will be described. Figure 7 is a diagram illustrating the flow of the manufacturing method of the multilayer ceramic capacitor 100.

[0078] (Process for producing raw material powder) First, a dielectric ceramic composition for forming the dielectric layer 11 is prepared. The A-site and B-site elements contained in the dielectric layer 11 are usually present in the form of a sintered body of ABO3 particles. For example, barium titanate is a compound that has a perovskite structure and belongs to the tetragonal crystal system at around room temperature, exhibiting a high dielectric constant. Barium titanate can generally be synthesized by reacting a titanium raw material such as titanium dioxide with a barium raw material such as barium carbonate and a calcium raw material such as calcium carbonate. Various methods have been conventionally known for synthesizing barium titanate, which is the main component of the dielectric layer 11, such as the solid-phase method, the sol-gel method, and the hydrothermal method. In this embodiment, any of these methods can be employed.

[0079] In this embodiment, when synthesizing barium titanate, 0.01 mol to 0.1 mol of molybdenum oxide is added per 100 mol of barium titanate (in terms of molybdenum equivalent). Adding molybdenum during barium titanate synthesis allows Mo to be dissolved in the core, thereby improving reliability.

[0080] A predetermined additive is added to the molybdenum-soluble barium titanate powder obtained by the above method. In order to form a core-shell structure, it is preferable to add manganese and rare earth elements after the synthesis of the molybdenum-soluble barium titanate powder. As an example, additives within the range shown in the example of the dielectric ceramic composition according to the first embodiment are used. If necessary, oxides or glasses containing zirconium (Zr), vanadium (V), chromium (Cr), cobalt (Co), nickel (Ni), lithium (Li), boron (B), sodium (Na), and potassium (K) may be used.

[0081] For example, a ceramic material is prepared by wet-mixing a compound containing an additive compound with molybdenum-soluble barium titanate powder, drying and pulverizing the mixture of molybdenum-soluble barium titanate powder and the additive compound. For example, the ceramic material obtained as described above may be pulverized as needed to adjust the particle size, or the particle size may be adjusted by combining this with a classification process. Specifically, the particle size can be adjusted by stirring the ceramic material together with beads made of yttrium-stabilized zirconia, alumina, or silicon nitride, with a diameter of 0.1 mm to 3 mm, for 10 to 100 hours. A dielectric ceramic composition is obtained through the above process.

[0082] (Coating process) Next, a binder such as polyvinyl butyral (PVB) resin, an organic solvent such as ethanol or toluene, and a plasticizer are added to the obtained dielectric ceramic composition and wet-mixed. Using the resulting slurry, a ceramic green sheet 51 is coated onto a substrate by, for example, a die coater or doctor blade method and then dried. The substrate is, for example, polyethylene terephthalate (PET) film. A diagram illustrating the coating process has been omitted.

[0083] (Internal electrode formation process) Next, as illustrated in Figure 8(a), a metal conductive paste for forming internal electrodes containing an organic binder is printed on the surface of the ceramic green sheet 51 by screen printing, gravure printing, or the like, thereby arranging an internal electrode pattern 52 that is alternately drawn out to a pair of external electrodes with different polarities. Ceramic particles are added to the metal conductive paste as a co-material. The main component of the ceramic particles is not particularly limited, but it is preferable that it is the same as the main component ceramic of the dielectric layer 11. For example, barium calcium titanate with an average particle diameter of 50 nm or less may be uniformly dispersed.

[0084] Next, a binder such as ethylcellulose and an organic solvent such as terpineol are added to the dielectric ceramic composition obtained in the raw material powder preparation process, and the mixture is kneaded in a roll mill to obtain a dielectric pattern paste for the reverse pattern layer. As illustrated in Figure 8(a), the dielectric pattern 53 is placed on the ceramic green sheet 51 by printing the dielectric pattern paste in the peripheral area where the internal electrode pattern 52 is not printed, thereby filling the step between it and the internal electrode pattern 52. The ceramic green sheet 51 with the internal electrode pattern 52 and dielectric pattern 53 printed on it is called a laminated unit.

[0085] Subsequently, as illustrated in Figure 8(b), stacking units are carried out so that the internal electrode layer 12 and the dielectric layer 11 are staggered, and the edges of the internal electrode layer 12 are alternately exposed on both ends of the dielectric layer 11 in the longitudinal direction, alternately leading to a pair of external electrodes 20a and 20b with different polarities. For example, the number of stacked internal electrode patterns 52 is set to 100 to 1000 layers.

[0086] (Crimping process) As illustrated in Figure 9, a predetermined number of cover sheets 54 (e.g., 2 to 10 layers) are laminated and heat-pressed onto the top and bottom of a laminate in which the laminated units are stacked. As an example of the ceramic material for the cover sheets 54, the dielectric ceramic composition described above can be used. After that, it is cut to a predetermined chip size (e.g., 1.0 mm × 0.5 mm).

[0087] (Firing process) The ceramic laminate thus obtained is subjected to a binder removal treatment in an N2 atmosphere, an air atmosphere, etc., and then a metal paste that will serve as the base layer for the external electrodes 20a and 20b is applied by the dip method, with an oxygen partial pressure of 10 -10 ~10 -7 The capacitor is kept at 800°C to 1100°C for 10 minutes to 1 hour in a reducing atmosphere (ATM), and then fired at 1150°C to 1300°C for 10 minutes to 2 hours. In this way, a multilayer ceramic capacitor 100 is obtained.

[0088] (Re-oxidation process) Subsequently, a re-oxidation treatment may be performed in an N2 gas atmosphere at 600°C to 1000°C.

[0089] (Plating process) Subsequently, a metal coating of Cu, Ni, Sn, etc. is applied to the underlayer of the external electrodes 20a and 20b by plating. Through these steps, the multilayer ceramic capacitor 100 is completed.

[0090] The side margin portion may be attached or coated to the side surface of the laminated portion. Specifically, as illustrated in Figure 10, a laminated portion is obtained by alternately stacking a ceramic green sheet 51 and an internal electrode pattern 52 with the same width as the ceramic green sheet 51. Next, a sheet formed from dielectric pattern paste may be attached to the side surface of the laminated portion as a side margin portion 55.

[0091] According to the manufacturing method of this embodiment, the oxygen partial pressure 10 -10 ~10 -7By maintaining a temperature of 800-1100°C for 10 minutes to 1 hour in a reducing atmosphere of atm, the added rare earth element R and titanium form a compound R2Ti2O7 with a pyrochlore or perovskite slab structure. Subsequently, when the temperature is raised to 1100-1300°C, it reacts with the surface of the barium titanate crystal grains, forming a shell portion 412 in the form of a composite perovskite compound, such as R(Ti,Mn)O3. Furthermore, by rapidly increasing the heating rate from 3000°C / h to 10000°C / h when raising the temperature to 1100-1300°C, a second crystal grain 42 is generated. This suppresses the change in capacitance due to the firing temperature. As a result, high mass productivity can be achieved.

[0092] The dependence of the dielectric constant of the multilayer ceramic capacitor 100 on firing temperature (Δε / °C) is determined by the following method. First, the capacitance Cp (nF) and DC current I (nA) are measured for the multilayer ceramic capacitor 100 after it has undergone firing, re-oxidation, and plating processes. Next, the capacitance region 14 of the multilayer ceramic capacitor 100 is exposed by cutting or polishing the cross-sections along the AA and BB lines as illustrated in Figures 5 and 6, and finally, the effective area of ​​the internal electrode layer is calculated when a smooth surface that can be judged as a mirror surface is obtained using a diamond paste of 2 μm or less.

[0093] The effective area S is calculated from the length L and number of layers N of the internal electrode layer 12 in the capacitance region 14 in Figure 5, and the width W of the internal electrode layer 12 in the capacitance region 14 in Figure 6, according to the formula S = L × W × (N-1).

[0094] At this time, the thickness of each dielectric layer 11 is also measured, and the average thickness t is calculated. In this case, the relative permittivity ε is ε = (Cp × t / S) / ε0, and the permittivity of vacuum is ε0 = 8.8542 × 10⁻⁶. -12 It can be calculated according to F / m.

[0095] Furthermore, the DC resistivity ρ (Ω·cm) can be calculated according to the formula ρ = (V / I) × (S / t), where V (V) is the DC voltage during measurement.

[0096] Regarding capacitance Cp, it is generally preferable to measure it using an LCR meter. When measuring, it is necessary to determine the measurement frequency and measurement voltage, and it is preferable to determine the measurement voltage as a measurement electric field that depends on the thickness of the dielectric layer 11. In this embodiment, capacitance Cp can be measured at room temperature of 25°C, with a measurement frequency of 1 kHz and a measurement electric field of 0.5 Vrms / μm, that is, 1 Vrms when the thickness of the dielectric layer 11 is 2 μm.

[0097] Furthermore, the DC current I is generally preferably measured using an insulation resistance meter. While it is necessary to determine the measurement voltage, it is preferable to determine it as a measurement electric field that depends on the thickness of the dielectric layer 11. In this embodiment, the multilayer ceramic capacitor 100 is held in a 150°C constant temperature bath for 30 minutes, insulation from the surroundings is ensured using ceramic insulators, etc., and a measurement electric field of 30V / μm (for example, 60V for 30 seconds if the thickness of the dielectric layer 11 is 2μm) is applied through wires connected to external electrodes 20a and 20b from the constant temperature bath to measure the DC current I and calculate the DC resistivity ρ. Unless otherwise specified, the measurement shall be performed in accordance with Japanese Industrial Standard C5101-22:2021, Fixed Capacitors for Electronic Equipment - Part 22: General Rules by Type - Surface Mount Fixed Multilayer Ceramic Capacitors, Type 2.

[0098] Next, the DC resistivity ρ is measured for multilayer ceramic capacitors obtained at each firing temperature, and the firing temperature that maintains the highest resistivity is determined as the optimal firing temperature. Generally, if the firing temperature is too low, the density becomes low and the resistivity becomes low, and if the firing temperature is too high, the ceramic particles become larger and the number of grain boundaries decreases, resulting in a decrease in resistivity.

[0099] Next, the relative permittivity ε of the multilayer ceramic capacitor obtained at the firing temperature that maintains the highest resistivity, and the relative permittivity of the multilayer ceramic capacitor obtained by firing at firing temperatures of -20°C and +20°C (derived from the firing temperature that maintains the highest resistivity), are used to determine the slope of the straight line using the least squares method based on these firing temperatures and relative permittivity. This value is then used to determine the firing temperature dependence of the relative permittivity (Δε / °C), which serves as an indicator of high mass production capability.

[0100] Next, the reliability of the multilayer ceramic capacitor 100 obtained at the firing temperature that maintains the highest resistivity will be investigated. Reliability will be determined by performing a HALT test at 50V-150℃. The HALT lifetime will be calculated by averaging the values ​​of 100 samples.

[0101] The DC resistivity measured at 150°C was 1.0 × 10⁻⁶. 8 It is desirable that the value be greater than or equal to Ω·cm. 1.0 × 10 8 By achieving a resistance of Ω·cm or higher, the multilayer ceramic capacitor 100 using the dielectric ceramic composition of this embodiment can be made to have sufficient resistance.

[0102] Preferably, Δε / ℃ is 10 or less. When it is 10 or less, the multilayer ceramic capacitor 100 using the dielectric ceramic composition of this embodiment can achieve firing in a shorter time while suppressing changes in capacitance due to changes in firing temperature, thereby achieving high mass production efficiency.

[0103] The relative permittivity ε should preferably be 2000 or higher. The DC resistivity measured at 150°C should be 2.0 × 10⁻⁶. 8 Even if the dielectric constant is greater than Ω·cm and the firing temperature dependence Δε / ℃ of the relative permittivity is 12 or less, if ε is small, the capacitance Cp will be an insufficient value, resulting in characteristics unsuitable for the application of the multilayer ceramic capacitor 100 using a dielectric ceramic composition.

[0104] In the embodiments described above, multilayer ceramic capacitors were explained as an example of multilayer ceramic electronic components, but the invention is not limited to them. For example, other multilayer ceramic electronic components such as varistors and thermistors may be used. [Examples]

[0105] (Example 1) During the synthesis of barium titanate, a molybdenum solid-solution barium titanate powder with an average particle size of 200 nm was prepared by adding 0.01 mol of MoO3 to 100 mol of barium titanate. To this barium titanate powder, 0.75 mol of Gd2O3, 3.00 mol of TiO2, 1.00 mol of MnCO3, 1.00 mol of SiO2, and 0.50 mol of MgO were added to obtain a dielectric ceramic composition.

[0106] A dielectric slurry was prepared by mixing a dielectric ceramic composition with ethanol, toluene, and PVB (polyvinyl butyral) resin. This slurry was molded into a ceramic green sheet using a die coater. After drying the ceramic green sheet, nickel paste was printed to form the internal electrode pattern. The resulting laminated units were stacked and pressed together with thick layers of ceramic green sheets without internal electrode patterns on the top and bottom, and then cut into small pieces. After that, Ni paste was dipped into two end faces as a conductive paste for the external electrodes, and degreasing was performed in nitrogen gas. The degreasing pieces were then fired and sintered in a reducing atmosphere controlled to maintain an oxygen partial pressure that prevents nickel oxidation, thereby producing a multilayer ceramic capacitor. The firing was performed by maintaining the temperature at 1000°C for 10 minutes and then at 1240°C for 10 minutes.

[0107] The fabricated multilayer ceramic capacitor had a 1005 shape (1.0 mm × 1.0 mm × 0.5 mm). It was then re-oxidized at 950°C. Following this, plating was performed to form Cu, Ni, and Sn plating layers on the surface of the base layer, resulting in a multilayer ceramic capacitor. The average thickness of the dielectric layer 11 was 2.0 μm.

[0108] (Example 2) In Example 2, 100 moles of molybdenum-soluble barium titanate powder with an average particle size of 200 nm, obtained by adding 0.03 moles of MoO3 to 100 moles of barium titanate during barium titanate synthesis, were used. To this powder, 0.75 moles of Gd2O3, 3.00 moles of TiO2, 1.00 moles of MnCO3, 1.00 moles of SiO2, and 0.50 moles of MgO were added to obtain a dielectric ceramic composition. For firing, the temperature was maintained at 1000°C for 10 minutes, and then at 1230°C for 10 minutes. Other conditions were the same as in Example 1.

[0109] (Example 3) In Example 3, 100 moles of molybdenum-soluble barium titanate powder with an average particle size of 200 nm, obtained by adding 0.05 moles of MoO3 to 100 moles of barium titanate during barium titanate synthesis, were to be mixed with 0.75 moles of Gd2O3, 3.00 moles of TiO2, 1.00 moles of MnCO3, 1.00 moles of SiO2, and 0.50 moles of MgO to obtain a dielectric ceramic composition. The firing was performed by maintaining the temperature at 1000°C for 10 minutes and then at 1230°C for 10 minutes. Other conditions were the same as in Example 1.

[0110] (Example 4) In Example 4, 100 moles of molybdenum-soluble barium titanate powder with an average particle size of 200 nm, obtained by adding 0.07 moles of MoO3 to 100 moles of barium titanate during barium titanate synthesis, were to be mixed with 0.75 moles of Gd2O3, 3.00 moles of TiO2, 1.00 moles of MnCO3, 1.00 moles of SiO2, and 0.50 moles of MgO to obtain a dielectric ceramic composition. The firing was performed by maintaining the temperature at 1000°C for 10 minutes and then at 1220°C for 10 minutes. Other conditions were the same as in Example 1.

[0111] (Example 5) To obtain a dielectric ceramic composition, 100 moles of molybdenum-soluble barium titanate powder with an average particle size of 200 nm, obtained by adding 0.10 moles of MoO3 to 100 moles of barium titanate during barium titanate synthesis, were mixed with 0.75 moles of Gd2O3, 3.00 moles of TiO2, 1.00 moles of MnCO3, 1.00 moles of SiO2, and 0.50 moles of MgO. The mixture was fired at 1000°C for 10 minutes, followed by 1220°C for 10 minutes. Other conditions were the same as in Example 1.

[0112] (Comparative Example 1) In Comparative Example 1, 0.75 mol of Gd2O3, 3.00 mol of TiO2, 1.00 mol of MnCO3, 1.00 mol of SiO2, and 0.50 mol of MgO were added to 100 mol of barium titanate powder with an average particle size of 200 nm that had not been dissolved with molybdenum, in order to obtain a dielectric ceramic composition. For firing, the temperature was maintained at 1000°C for 10 minutes, and then at 1240°C for 10 minutes. Other conditions were the same as in Example 1.

[0113] For each of the multilayer ceramic capacitors in Examples 1-5 and Comparative Example 1, the capacitance Cp was measured at room temperature (25°C) at 1kHz and 1Vrms using an LCR meter, and the DC current I was measured at 150°C when 60V was applied for 30 seconds using an insulation resistance meter. In addition, the cross-sections along lines AA and BB in Figure 4 were exposed, and the effective area S of the internal electrode layer and the average thickness t of the dielectric layer were calculated. From the effective area S and average thickness t, the relative permittivity ε and resistivity ρ were calculated. Then, the resistivity ρ of each multilayer ceramic capacitor in Examples 1-5 and Comparative Example 1 was compared, and the relative permittivity of the multilayer ceramic capacitor fired at -20°C and +20°C was referenced from the firing temperature that yielded the highest resistivity. Based on these firing temperatures and relative permittivity, the slope of the line was determined using the least squares method and defined as the firing temperature dependence of the relative permittivity (Δε / °C).

[0114] Reliability tests were performed on each of the multilayer ceramic capacitors in Examples 1-5 and Comparative Example 1. Compared to Comparative Example 1, if the average lifespan was more than twice as long, the reliability was judged as good ("○"). If the average lifespan was less than twice as long, the reliability was judged as being at the same level or worse, and the capacitor was judged as unsatisfactory ("×").

[0115] Furthermore, an osmium conductive material was deposited onto the exposed dielectric layer, and images of the crystalline particles present in the dielectric layer were taken using SEM observation. The average particle size of the crystalline particles constituting the dielectric layer was then calculated. The average particle size was 270 nm in Example 1, 260 nm in Example 2, 260 nm in Example 3, 280 nm in Example 4, 270 nm in Example 5, and 280 nm in Comparative Example 1.

[0116] In addition, during SEM observation of the multilayer ceramic capacitor, the presence of the second crystal grain 42 was confirmed in the BSE image by the difference in its brightness.

[0117] For each multilayer ceramic capacitor, in order to confirm the composition of the shell and core portions of the dielectric layer's crystal grains and the second crystal grain 42, samples for EDS observation using TEM were cut out by FIB, and the presence of a core-shell structure was confirmed using the EDS composition evaluation method. The core portion was defined as having an R / Ti elemental ratio of less than 0.02, and the shell portion as having an R / Ti ratio of 0.02 or more.

[0118] Table 1 summarizes the amounts of additives used in Comparative Example 1 and Examples 1-5. Table 2 summarizes the firing temperature, average particle size, ε, Δε / °C, resistivity at 150°C, and reliability relative to Comparative Example 1 for Comparative Example 1 and Examples 1-5. The pass / fail criteria were Δε / °C of 10 or less and resistivity of 1.0 × 10⁻⁶. 8 Tests meeting the criteria of Ω·cm or higher and a reliability of 2x or higher were marked as passing (○), while those failing to meet these criteria were marked as failing (×). [Table 1] [Table 2]

[0119] Furthermore, to investigate the dielectric layer mechanism in detail, STEM-EDS was used to examine the presence or absence of a core-shell structure, the elemental ratio of Mo to Ti in the first crystal grain 41, the presence or absence of second crystal grains 42, and the elemental ratio of Ba to Ti in the second crystal grains 42 for the multilayer ceramic capacitors obtained in Comparative Example 1 and Examples 1-5. The results are summarized in Table 3. In all of Comparative Example 1 and Examples 1-5, second crystal grains 42 with an elemental ratio of barium to titanium of 0.70 or less were confirmed. However, while first crystal grains 41 having a core portion containing molybdenum and a shell portion containing rare earth elements and manganese were confirmed in Examples 1-5, molybdenum was not confirmed in the core portion of Comparative Example 1. This is thought to be because Comparative Example 1 used barium titanate without solid solution of molybdenum. [Table 3]

[0120] As shown in Table 2, the Δε / ℃ values ​​for Examples 1 to 5 were 10 or less. For example, even when a larger firing furnace than the existing one was used to increase productivity, the dielectric constant obtained with respect to the temperature distribution inside the furnace, i.e., the capacitance Cp of the multilayer ceramic capacitor, did not have a large distribution. Therefore, mass production can be made even with firing in a short time by rapid heating. In addition, by including an appropriate amount of molybdenum, it had more than twice the reliability compared to Comparative Example 1.

[0121] Examples 1 to 5 all passed with a "○". This is thought to be because the dielectric layer in Examples 1 to 5 contained first crystalline particles 41 and second crystalline particles 42. This is a surprising effect that was not expected from conventional dielectric ceramic compositions. In contrast, Comparative Example 1 failed with a "×". This is thought to be because the dielectric layer in Comparative Example 1 did not contain first crystalline particles 41.

[0122] Although embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. [Explanation of Symbols]

[0123] 10 stacked chips 11 Dielectric layer 12 Internal electrode layer 13. Cover layer 14 Capacity area 15 End margin 16 Side margins 20a,20b external electrode 41. First crystal particle 42 Second Crystal Particle 43 Crystal Particles 51 Ceramic Green Sheet 52 Internal electrode patterns 53 Dielectric Pattern 54 Cover Sheets 55 Side margin section 100 Multilayer Ceramic Capacitors

Claims

1. General formula ABO ３ A dielectric layer having a perovskite structure represented by , a first crystalline particle having a core portion containing molybdenum and a shell portion covering the core portion and containing rare earth elements and manganese, and a second crystalline particle mainly composed of barium titanate with an elemental ratio of barium to titanium of 0.70 or less, Multiple internal electrode layers facing each other across the dielectric layer, A multilayer ceramic electronic component having an external electrode electrically connected to the internal electrode layer.

2. The A site of the perovskite structure contains barium, The multilayer ceramic electronic component according to claim 1, wherein the elements contained in the B site of the perovskite structure include at least one of titanium or zirconium.

3. The multilayer ceramic electronic component according to claim 1, wherein the rare earth element is at least one selected from lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, and ytterbium.

4. The multilayer ceramic electronic component according to claim 1, wherein the first crystal grain has an elemental ratio of molybdenum to titanium of 0.001 or more.

5. The multilayer ceramic electronic component according to claim 1, wherein the second crystal grain has an elemental ratio of molybdenum to titanium of less than 0.

01.

6. The second crystal particles are BaTi ４ O ９ 、BaTi ５ O １１ 、BaTi ６ O １３ 、Ba ４ Ti １１ O ２６ 、Ba ４ Ti １２ O ２７ 、Ba ４ Ti １３ O ３０ 、or Ba ６ Ti １７ O ４０ The multilayer ceramic electronic component according to claim 1, comprising at least one selected from the above.

7. The multilayer ceramic electronic component according to claim 1, wherein the maximum particle diameter of the first crystal particle is 2 μm or less.

8. The multilayer ceramic electronic component according to claim 1, wherein the shell portion contains magnesium and manganese.

9. General formula ABO ３ A first crystal grain having a perovskite structure represented by , comprising a core portion containing molybdenum, and a shell portion covering the core portion and containing rare earth elements and manganese, A dielectric ceramic composition comprising barium titanate as the main component, and a second crystalline particle having an elemental ratio of barium to titanium of 0.70 or less.

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