Dielectric ceramic forming composition and dielectric ceramic material

Abstract

Provided are a composition for forming a dielectric ceramic capable of obtaining a perovskite-type composite oxide having a small particle size and high crystallinity, and a dielectric ceramic material using the same. A composition for forming a dielectric ceramic, characterized by containing a raw material perovskite (ABO3)-type composite oxide and a compound having a bond represented by the following formula (1), the content of the compound having the bond represented by the general formula (1) being 0.40 mol% to 80 mol% relative to the raw material perovskite (ABO3)-type composite oxide.

Description

Technical Field

[0001] This invention relates to compositions for forming dielectric ceramics containing perovskite-type composite oxides useful as raw materials for functional ceramics such as dielectrics, optoelectronic materials, piezoelectrics, semiconductors, and sensors, and dielectric ceramic materials obtained by firing the compositions. Background Technology

[0002] Perovskite-type composite oxides, represented by barium titanate, have long been used as raw materials for functional ceramics such as piezoelectric elements and multilayer ceramic capacitors. However, in recent years, multilayer ceramic capacitors have required increased layer count and higher dielectric constant to achieve higher capacitance. Therefore, perovskite-type composite oxides are required to be fine-grained and possess high tetragonal crystallinity.

[0003] Barium titanate is a representative example of perovskite-type composite oxides. Methods for manufacturing barium titanate include solid-state synthesis, hydrothermal synthesis, alkoxide synthesis, and oxalate synthesis. These methods all involve reacting a titanium source with a barium source to obtain barium titanate, but typically the final step involves applying heat, such as through sintering. To achieve high crystallinity, even more heat is required.

[0004] Applying heat energy to achieve this high crystallinity can be achieved simply by increasing the firing temperature, but this results in high crystallinity of the obtained perovskite-type composite oxide. On the other hand, it promotes grain growth, thus making it impossible to achieve the goal of obtaining the fine raw material as described above.

[0005] To address this issue, for example, Patent Document 1 describes a method for preparing barium titanate with a narrow particle size distribution and small average particle size by adding an auxiliary agent composed of an amide compound, amino acid, or peptide before calcination during the mixing and calcination of barium carbonate and titanium oxide as raw materials. Furthermore, Patent Document 2 discloses a method for preparing barium carbonate as a raw material for perovskite-type composite oxides, and describes how fine barium carbonate is obtained by reacting barium compounds such as barium hydroxide and barium chloride with polycarboxylic acids such as citric acid and tartaric acid, making it suitable for use in electronic materials such as multilayer ceramic capacitors obtained using this barium carbonate as a raw material. Patent Document 3 describes barium titanate with excellent dielectric properties obtained by adding nitrogen-containing additives such as ammonia to the crystallization of barium titanate oxalate, followed by pulverization and thermal decomposition.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2006-111524

[0009] Patent Document 2: Japanese Patent Application Publication No. 2019-189493

[0010] Patent Document 3: Japanese Patent Application Publication No. 2005-500239 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] The invention disclosed in the aforementioned patent documents involves adding additives at the raw material stage to primarily promote the decomposition of barium compounds or inhibit grain growth and increase the specific surface area during subsequent firing, thereby generating fine barium titanate. However, barium titanate obtained by this method cannot achieve highly crystalline barium titanate without increasing the firing temperature to a certain extent. Therefore, it is necessary to explore a method for obtaining fine and highly crystalline barium titanate even during low-temperature firing.

[0013] Therefore, the object of the present invention is to provide a composition for forming dielectric ceramics that can obtain perovskite-type composite oxides with small particle size and high crystallinity, and to provide a dielectric ceramic material using the composition for forming dielectric ceramics.

[0014] Technical solutions for solving the problem

[0015] In view of the actual situation, the inventors have repeatedly conducted in-depth research and found that by adding specific compounds to the perovskite-type composite oxide as a raw material and then firing it, perovskite-type composite oxide can be obtained at a lower temperature than currently available. Therefore, high crystallinity can be achieved while suppressing grain growth, thus completing the present invention.

[0016] That is, the present invention provides a composition for forming dielectric ceramics, characterized in that,

[0017] Compounds containing perovskite (ABO3) type complex oxides and bonds represented by the following formula (1).

[0018] [Chemical Formula 1]

[0019]

[0020] The content of the compound having bonds represented by general formula (1) is 0.40 mol% to 80 mol% relative to the perovskite (ABO3) type complex oxide.

[0021] In addition, the present invention provides a dielectric ceramic material obtained by firing the aforementioned dielectric ceramic forming composition.

[0022] Invention Effects

[0023] According to the present invention, a composition for forming dielectric ceramics can be provided, which, when fired at the same temperature, can produce perovskite-type composite oxides with smaller particle size and higher crystallinity compared to existing perovskite-type composite oxides, and a dielectric ceramic material using the composition for forming dielectric ceramics can be provided. Attached Figure Description

[0024] Figure 1 The DTG curve is obtained by thermogravimetric analysis of the dielectric ceramic forming composition of Example 1.

[0025] Figure 2 The DTG curve is obtained by thermogravimetric analysis of the dielectric ceramic forming composition of Example 2.

[0026] Figure 3 The DTG curve is obtained by thermogravimetric analysis of the dielectric ceramic forming composition of Example 3.

[0027] Figure 4 The DTG curve of the dry powder of Comparative Example 1 was obtained by calorimetric analysis.

[0028] Figure 5 The DTG curves of the dielectric ceramic forming composition of Comparative Example 2 were obtained by thermogravimetric analysis.

[0029] Figure 6 This is a graph showing the relationship between the BET specific surface area and c / a in Table 2. Detailed Implementation

[0030] The present invention will now be described based on its preferred embodiments.

[0031] The dielectric ceramic forming composition of the present invention is characterized in that it contains a perovskite (ABO3) type composite oxide and a compound having a bond represented by the following formula (1).

[0032] [Chemical Formula 1]

[0033]

[0034] The content of the compound having the bond represented by the general formula (1) is 0.40 mol% to 80 mol% relative to the perovskite (ABO3) type complex oxide of the raw material.

[0035] The dielectric ceramic forming composition of the present invention contains a raw material perovskite (ABO3) type composite oxide. The raw material perovskite (ABO3) type composite oxide contained in the dielectric ceramic forming composition of the present invention is sintered by firing the dielectric ceramic forming composition to form a sintered body of the perovskite (ABO3) type composite oxide, i.e., a raw material composite oxide used to form dielectric ceramic materials.

[0036] The perovskite (ABO3) type composite oxide used as the raw material for the dielectric ceramic forming composition of the present invention is not particularly limited as long as it is a perovskite-type composite oxide having an ABO3 structure. Preferably, it is a perovskite-type composite oxide where the A-site element is at least one selected from Ba, Ca, Mg, and Sr, and the B-site element is at least one selected from Ti and Zr. Examples of such perovskite (ABO3) type composite oxides include barium titanate, calcium titanate, magnesium titanate, strontium titanate, barium calcium titanate, barium zirconate, barium strontium titanate, barium zirconate, calcium zirconate, strontium zirconate, barium calcium zirconate, barium strontium zirconate, and calcium strontium zirconate. The perovskite (ABO3) type composite oxide can be a single type or a combination of two or more types. Among them, barium titanate is particularly preferred as a raw material for perovskite (ABO3) type composite oxides in terms of obtaining perovskite type composite oxides with higher crystallinity by low-temperature calcination.

[0037] The average particle size of the raw material perovskite (ABO3) type composite oxide is preferably 0.010–10 μm, more preferably 0.020–10 μm. When the average particle size of the raw material perovskite (ABO3) type composite oxide is within the above range, the electrical properties, sintering properties, and processing properties of the perovskite type composite oxide become favorable. Furthermore, in this invention, regarding the average particle size of the raw material perovskite (ABO3) type composite oxide, the particle size of 200 particles is randomly measured using a scanning electron microscope (SEM), and the average value is set as the average particle size.

[0038] The preferred BET specific surface area of ​​the raw material perovskite (ABO3) type composite oxide is 0.10 m². 2 / g or more, preferably 1.0m 2 / g~50m 2 / g. Since the BET specific surface area of ​​the raw material perovskite (ABO3) type composite oxide is within the above range, its sinterability and processability become good, resulting in a perovskite type composite oxide with small particle size and high crystallinity, which is therefore preferred.

[0039] There are no particular limitations on the preparation method of the raw material perovskite-type composite oxide, such as the oxalate method, co-precipitation method, hydrolysis method, hydrothermal synthesis method, solid-state method, etc. Alternatively, commercially available perovskite-type composite oxides can also be used.

[0040] The dielectric ceramic forming composition of the present invention contains a compound having bonds represented by the following formula (1).

[0041] [Chemical Formula 1]

[0042]

[0043] A compound having a bond represented by general formula (1) has at least one bond represented by general formula (1) in its molecule. In the dielectric ceramic forming composition of the present invention, the compound having a bond represented by general formula (1) is the compound required to make the dielectric ceramic material obtained by firing the dielectric ceramic forming composition into a perovskite-type composite oxide with small particle size and high crystallinity. In the absence of a compound having a bond represented by general formula (1), it is necessary to apply heat energy by increasing the firing temperature in order to improve the crystallinity of the raw perovskite-type composite oxide. In contrast, by having a compound having a bond represented by general formula (1), it is possible to easily crystallize the raw perovskite-type composite oxide. Therefore, even without increasing the firing temperature, the crystallinity becomes higher, and since it is not necessary to increase the firing temperature, grain growth is suppressed. The inventors believe that the reason for this is that, in the raw material perovskite-type composite oxide, although compounds containing the A-site element of the raw material perovskite-type composite oxide, such as hydroxides, chlorides, nitrates, acetates, oxides, or carbonates of Ba, Ca, Mg, or Sr, are attached to the particle surface of the raw material perovskite-type composite oxide, or, as described later in this invention, the above-mentioned compounds containing the A-site element are added to the raw material perovskite-type composite oxide for the purpose of improving crystallinity, the presence of the above-mentioned compounds having bonds represented by general formula (1) promotes the decomposition of the above-mentioned compounds containing the A-site element, making the reaction between the A-site element and the raw material perovskite-type composite oxide easier. In addition, in the compounds having bonds represented by general formula (1), the carbon atom in general formula (1) is bonded to another atom in addition to being bonded to the oxygen atom and nitrogen atom in general formula (1), and the nitrogen atom in general formula (1) is bonded to two other atoms in addition to being bonded to the carbon atom in general formula (1).

[0044] As compounds having bonds represented by general formula (1), examples include amide compounds represented by general formula (2).

[0045] [Chemical Formula 2]

[0046]

[0047] Amide compounds are compounds that have an amide skeleton (-C(=O)-N-) in their molecules. In formula (2), R 1 R 2 and R 3 It is either H or an organic group, chosen independently. As R in formula (2) 1 R 2 and R 3 Organic groups, such as alkyl, alkenyl, aromatic groups, etc., may also have substituents such as alkyl and halogen.

[0048] In addition, urea compounds represented by the general formula (3) can be cited as examples of compounds having bonds represented by the general formula (1).

[0049] [Chemical Formula 3]

[0050]

[0051] Urea compounds are compounds that have a urea skeleton (-N-C(=O)-N-) in their molecules. In formula (3), R 1 R 2 R 3 and R 4 It is either H or an organic group, chosen independently. As R in formula (3) 1 R 2 R 3 and R 4 Organic groups, such as alkyl, alkenyl, aromatic groups, etc., may also have substituents such as alkyl and halogen.

[0052] In addition, as compounds having bonds represented by general formula (1), examples include imide compounds represented by general formula (4).

[0053] [Chemical Formula 4]

[0054]

[0055] Imide compounds are compounds that have an imide skeleton (-C(=O)-N-C(=O)-) in their molecules. In formula (4), R 1 R 2 and R 3 It is either H or an organic group, chosen independently. As R in formula (4) 1 R 2 and R 3 Organic groups, such as alkyl, alkenyl, aromatic groups, etc., may also have substituents such as alkyl and halogen.

[0056] Amide compounds having bonds represented by the general formula (1) include acetamide, formamide, propionamide, butylamide, diacetamide, succinamide, ε-caprolactam, acrylamide, acetanilide, nicotinamide, oleamide, stearamide, etc.

[0057] In addition, examples of urea compounds having bonds represented by the general formula (1) include urea, methylurea, ethylurea, butylurea, acetylurea, etc.

[0058] In addition, examples of imide compounds having bonds represented by the general formula (1) include phthalimide, succinimide, hydantoin, barbituric acid, and isocyanuric acid.

[0059] Among these, urea compounds such as urea, methylurea, ethylurea, butylurea, and acetylurea are preferred as compounds having bonds represented by the general formula (1) in terms of high reactivity and low cost, with urea being particularly preferred.

[0060] Compounds with bonds represented by general formula (1) can be a single type or a combination of two or more types.

[0061] In the composition for forming dielectric ceramics, the content of compounds having bonds represented by general formula (1) relative to the raw material perovskite (ABO3) type composite oxide is 0.40 mol% to 80 mol%, preferably 0.80 mol% to 60 mol%, and particularly preferably 2.0 mol% to 40 mol%. By keeping the content of compounds having bonds represented by general formula (1) in the composition for forming dielectric ceramics within the above range, even when firing at low temperatures, the crystallization of the perovskite type composite oxide can be promoted while simultaneously inhibiting grain growth. Therefore, it is possible to obtain a dielectric ceramic material composed of a sintered body of perovskite type composite oxide with small grain size and high crystallinity. On the other hand, if the content of compounds having bonds represented by general formula (1) in the composition for forming dielectric ceramics is less than the above range, the effect of adding compounds having bonds represented by general formula (1) cannot be obtained when firing the composition for forming dielectric ceramics. Therefore, high-temperature firing is required, which results in grain growth. Furthermore, if the content of compounds having bonds represented by general formula (1) in the composition for forming dielectric ceramics exceeds the above range, it will lead to adverse effects on the physical properties, reactivity, and working environment of the product or an increase in manufacturing costs.

[0062] The effect of the dielectric ceramic forming composition of the present invention containing a compound having a bond represented by general formula (1) can be evaluated using a DTG curve, which is a differential curve of a thermogravimetric curve (TG curve) obtained by thermogravimetric analysis of the weight change of the dielectric ceramic forming composition of the present invention during heating. Specifically, when performing thermogravimetric analysis on the dielectric ceramic forming composition of the present invention, the minimum value of the peak of the thermal decomposition reaction of the compound containing the A-site element of the raw material perovskite-type composite oxide is preferably observed in the DTG curve at 500°C to 595°C, and particularly preferably at 510°C to 590°C. Since the minimum value of the peak in the DTG curve is within the above range, the reaction between the raw material perovskite-type composite oxide and the A-site element can be carried out at a lower temperature. Therefore, the particle growth of the raw material perovskite-type composite oxide can be suppressed, while achieving high crystallinity.

[0063] In addition to containing a perovskite (ABO3) type composite oxide and a compound having a bond represented by general formula (1), the composition for forming dielectric ceramics of the present invention may also contain a hydroxy acid.

[0064] Examples of hydroxy acids used in the dielectric ceramic forming composition of the present invention include citric acid, tartaric acid, malic acid, glycolic acid, lactic acid, glyceric acid, hydroxybutyric acid, isocitric acid, squalane, mevalonic acid, pantothenic acid, ricinoleic acid, and salicylic acid. From the viewpoint of reactivity and cost, citric acid, tartaric acid, malic acid, glycolic acid, lactic acid, glyceric acid, and isocitric acid are preferred as hydroxy acids, with citric acid and tartaric acid being particularly preferred. The hydroxy acid can be a single type or a combination of two or more.

[0065] In the dielectric ceramic forming composition of the present invention, the content of hydroxy acid relative to the raw material perovskite (ABO3) type composite oxide is 0.010 mol% to 20 mol%, preferably 0.020 mol% to 10 mol%, and more preferably 0.030 mol% to 5.0 mol%. Since the content of hydroxy acid in the dielectric ceramic forming composition of the present invention is within the above range, grain growth of the raw material perovskite (ABO3) type composite oxide caused by firing can be suppressed, thus easily obtaining perovskite type composite oxides with small grain size.

[0066] The dielectric ceramic forming composition of the present invention may further comprise a compound containing an A-site element of the raw perovskite (ABO3) type composite oxide. In the dielectric ceramic forming composition of the present invention, the content of the compound containing the A-site element is preferably 0.10 mol% to 20 mol%, more preferably 0.20 mol% to 15 mol%. By ensuring that the content of the compound containing the A-site element in the dielectric ceramic forming composition is within the above range, a highly crystalline perovskite type composite oxide can be obtained.

[0067] The compound containing the A-site element of the perovskite (ABO3) type complex oxide is preferably selected from at least one of the hydroxides, chlorides, nitrates, acetates, oxides, and carbonates of Ba, Ca, Mg, or Sr. For example, when the perovskite (ABO3) type complex oxide is barium titanate, examples of compounds containing the A-site element include barium hydroxide, barium chloride, barium nitrate, barium acetate, barium oxide, and barium carbonate. Similarly, when the perovskite (ABO3) type complex oxide is calcium titanate, examples include calcium hydroxide, calcium chloride, calcium nitrate, calcium acetate, calcium oxide, and calcium carbonate. Furthermore, when the perovskite (ABO3) type complex oxide is magnesium titanate, examples include magnesium hydroxide, magnesium chloride, magnesium nitrate, magnesium acetate, magnesium oxide, and magnesium carbonate. Finally, when the perovskite (ABO3) type complex oxide is strontium titanate, examples include strontium hydroxide, strontium chloride, strontium nitrate, strontium acetate, strontium oxide, and strontium carbonate.

[0068] Furthermore, for the purpose of modifying various properties of dielectric ceramic materials, the dielectric ceramic forming composition of the present invention may also contain a compound powder containing at least one secondary component element selected from Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, V, Nb, Ta, Mn, Cr, Mo, and W. Examples of compounds containing secondary component elements include oxides, hydroxides, carbonates, sulfates, nitrates, chlorides, carboxylates, ammonium salts, and organic acid salts. These may be a single element or a combination of two or more.

[0069] The average particle size of the compound powder containing the secondary component element is preferably 0.010 μm to 5.0 μm, more preferably 0.020 μm to 3.0 μm. Because the average particle size of the compound powder containing the secondary component element is within this range, it allows for better contact with the raw perovskite (ABO3) type composite oxide, thereby improving the homogeneity of the obtained dielectric ceramic material, and is therefore preferred. Furthermore, the average particle size of the compound powder containing the secondary component element in this invention is a value obtained based on the D50 particle size from volume distribution measurements using laser diffraction scattering.

[0070] The preferred BET specific surface area of ​​the compound powder containing secondary constituent elements is 2.0 m². 2 / g or more, preferably 2.0m 2 / g~200m 2 / g. Since the BET specific surface area of ​​the compound powder containing secondary constituent elements is within the above range, the contact with the raw material perovskite (ABO3) type composite oxide becomes good, which can improve the homogeneity of the obtained dielectric ceramic material, and is therefore preferred.

[0071] The dielectric ceramic forming composition of the present invention is prepared by mixing a raw material perovskite (ABO3) type composite oxide, a compound having bonds represented by general formula (1), a hydroxy acid as needed, a compound containing the A-site element of the raw material perovskite (ABO3) type composite oxide, and / or a compound powder containing a secondary component element in a desired proportion. The mixing method is not particularly limited, and examples include wet mixing and dry mixing.

[0072] In the wet process, known equipment such as ball mills, bead mills, dispersion mills, homogenizers, vibratory mills, sand mills, grinding mills, and high-intensity mixers can be used. In contrast, in the dry process, known equipment such as high-speed mixers, super mixers, turbine mixers, Henschel mixers, Nota mixers, and ribbon mixers can be used.

[0073] From the viewpoint of producing a more uniform composition and obtaining a dielectric ceramic material with higher performance, the dielectric ceramic forming composition of the present invention is preferably prepared by a wet method. Examples of solvents used in wet mixing include water, methanol, ethanol, propanol, butanol, toluene, xylene, acetone, dichloromethane, ethyl acetate, dimethylformaldehyde, and diethyl ether. Among these, using alcohols such as methanol, ethanol, propanol, and butanol results in a more uniform composition, thus further improving the electrical properties of the dielectric ceramic material obtained by firing.

[0074] The dielectric ceramic material of the present invention is a material obtained by firing the dielectric ceramic forming composition of the present invention described above, i.e., a fired product of the dielectric ceramic forming composition of the present invention. The dielectric ceramic material of the present invention is a sintered body of a perovskite (ABO3) type composite oxide with small particle size and high crystallinity. The firing temperature for firing the dielectric ceramic forming composition of the present invention is not particularly limited as long as it is a temperature at which the dielectric ceramic forming composition can be sintered; however, considering the advantages of the present invention, it is preferably below 1000°C, more preferably 300°C to 970°C, and particularly preferably 400°C to 950°C. The firing time for firing the dielectric ceramic forming composition of the present invention is preferably 1 hour or more, and particularly preferably 1 hour to 48 hours. The atmosphere for firing the dielectric ceramic forming composition of the present invention can be any of an atmospheric atmosphere, an oxygen atmosphere, or an inert atmosphere, without particular limitation. Furthermore, the firing of the dielectric ceramic forming composition of the present invention can be performed multiple times as needed.

[0075] In the dielectric ceramic forming composition or dielectric ceramic material of the present invention, additives, organic binders, plasticizers, dispersants, and other compounding agents known in the manufacture of multilayer ceramic capacitors are mixed and dispersed, slurryed, and sheet-formed to obtain a ceramic sheet. Then, conductive paste for forming internal electrodes is printed on one side of the ceramic sheet. After drying, multiple ceramic sheets are stacked and then stacked in the thickness direction to form a multilayer body. The multilayer body is heated and subjected to a binder removal treatment, and then fired to obtain a sintered body. Next, In-Ga paste, Ni paste, Ag paste, nickel alloy paste, copper paste, copper alloy paste, etc., are coated onto the sintered body and then sintered, thereby enabling the manufacture of a multilayer capacitor.

[0076] In addition, for example, when combined with the dielectric ceramic forming composition or dielectric ceramic material of the present invention in resins such as epoxy resin, polyester resin, and polyimide resin, it can also be used as a material for printed circuit boards or multilayer printed circuit boards used as resin sheets, resin films, adhesives, etc.; a common material for suppressing the shrinkage difference between internal electrodes and dielectric layers; a substrate and circuit peripheral material for electrode ceramic circuit boards, glass ceramic circuit boards; a catalyst used in reactions such as removing waste gas and chemical synthesis; and a material added as a surface modifier for printing toner to apply antistatic or cleaning effects.

[0077] Example

[0078] The present invention will be described in more detail below through embodiments, but the present invention is not limited to these embodiments.

[0079] (1) Thermogravimetric analysis

[0080] Using a thermogravimetric analyzer TGA / DSC 1 manufactured by METTLER-TOLEDO Inc., the thermogravimetric curve (TG curve) and the differential curve (DTG curve) of the TG curve were measured on a 30 mg sample under the conditions of heating from 30 °C to 120 °C at a heating rate of 10 °C / min in an air flow of 50 mL / min.

[0081] (2) Average particle size

[0082] The particle size of any 200 particles was measured using scanning electron microscopy (SEM) images, and the average value was taken as the mean particle size.

[0083] (3) Specific surface area

[0084] It is obtained using the BET method.

[0085] (4) c / a value

[0086] The ratio c / a of the c-axis to the a-axis was determined using Cu-Kα rays as the radiation source and an X-ray diffraction apparatus (manufactured by Bruker, D8ADVANCE).

[0087] (Example 1)

[0088] 50g of barium titanate (manufactured by Nippon Chemical Industries, Ltd.), the raw material with the properties shown in Table 1, was placed in 450ml of pure water. Urea (manufactured by NacalaiTesque Co., Ltd.) and barium carbonate (manufactured by Nippon Chemical Industries, Ltd.) were added as complexing agents in proportions shown in Table 1, and the mixture was wet-mixed using a ball mill. The mixture was then dried at 115°C to obtain a dry powder, yielding a dielectric ceramic forming composition composed of barium titanate, urea, and barium carbonate. The results of thermogravimetric analysis of this composition are shown below. Figure 1 According to the analysis results, the decomposition temperature of the above-mentioned barium carbonate, obtained from the DTG curve, is 582.3℃.

[0089] The above-obtained dielectric ceramic forming composition was fired for 10 hours at the temperatures shown in Table 2 under atmospheric conditions to obtain fired barium titanate. The physical properties of the obtained barium titanate are shown in Table 2.

[0090] (Example 2)

[0091] 50g of barium titanate, the same raw material as in Example 1, was placed in 450ml of pure water. Urea (manufactured by Nacalai Tesque Co., Ltd.), citric acid (manufactured by Nacalai Tesque Co., Ltd.), tartaric acid (manufactured by Kanto Chemical Co., Ltd.), and barium carbonate (manufactured by Nippon Chemical Industry Co., Ltd.) as complexing agents were added relative to the barium titanate in the proportions shown in Table 1, and wet-mixed using a ball mill. Then, the mixture was dried at 115°C to obtain a dry powder, yielding a dielectric ceramic forming composition composed of barium titanate, urea, citric acid, tartaric acid, and barium carbonate. The results of thermogravimetric analysis of this composition are shown below. Figure 2 According to the analysis results, the decomposition temperature of the above-mentioned barium carbonate, obtained from the DTG curve, is 562.8℃.

[0092] The dielectric ceramic forming composition obtained above was fired under the same conditions as in Example 1 to obtain fired barium titanate. The physical properties of the obtained barium titanate are shown in Table 2.

[0093] (Example 3)

[0094] 50g of barium titanate, the same raw material as in Example 1, was placed in 450ml of pure water. Urea (manufactured by Nacalai Tesque Co., Ltd.) was added as a complex relative to the barium titanate in the proportions shown in Table 1, and the mixture was wet-mixed using a ball mill. Then, it was dried at 115°C to obtain a dry powder, yielding a dielectric ceramic forming composition composed of barium titanate and urea. The results of thermogravimetric analysis of this composition are shown below. Figure 3 According to the analysis results, the decomposition temperature of the barium compound in the mixture obtained based on the DTG curve is 580.5℃.

[0095] The dielectric ceramic forming composition obtained above was fired under the same conditions as in Example 1 to obtain fired barium titanate. The physical properties of the obtained barium titanate are shown in Table 2.

[0096] (Comparative Example 1)

[0097] 50g of barium titanate, the same raw material as in Example 1, was placed in 450ml of pure water and wet-mixed using a ball mill. Then, it was dried at 115°C to obtain a dry powder. Thermogravimetric analysis was performed on the dry powder. The results are shown below. Figure 4 According to the analysis results, the decomposition temperature of the barium compound in the dry powder obtained based on the DTG curve is 603.8℃. Furthermore, the barium titanate was calcined under the same conditions as in Example 1 to obtain calcined barium titanate. The physical properties of the obtained barium titanate are shown in Table 2.

[0098] (Comparative Example 2)

[0099] 50g of barium titanate, the same raw material as in Example 1, was placed in 450ml of pure water. Barium carbonate (manufactured by Nippon Chemical Industries, Ltd.) was then added relative to the barium titanate in the proportions shown in Table 1, and wet-mixed using a ball mill. The mixture was then dried at 115°C to obtain a dry powder, yielding a dielectric ceramic forming composition composed of barium titanate and barium carbonate. The results of thermogravimetric analysis of this composition are shown below. Figure 5 According to the analysis results, the decomposition temperature of the above-mentioned barium carbonate, obtained from the DTG curve, is 596.5℃.

[0100] The dielectric ceramic forming composition obtained above was fired under the same conditions as in Example 1 to obtain fired barium titanate. The physical properties of the obtained barium titanate are shown in Table 2.

[0101] [Table 1]

[0102]

[0103] [Table 2]

[0104]

[0105] Figure 6 In the diagram, the vertical axis is set to c / a, and the horizontal axis is set to specific surface area (SSA). The results in Table 2 are then represented using the plotted graph. Furthermore, Figure 6 In the figures, the drawings for each embodiment and comparative example are based on firing temperatures of 800°C, 850°C, and 900°C from right to left.

[0106] Based on the above results, it was determined that, compared with Comparative Examples 1 and 2, the compositions for forming dielectric ceramics in Examples 1 and 2 yielded barium titanate that was less prone to grain growth, had smaller grain size, and exhibited higher crystallinity. Furthermore, it was found that, compared with Comparative Example 2 which only added barium carbonate, Example 3, which only added urea, had a higher c / a value and promoted crystallization when compared at the same firing temperature.

Claims

1. A composition for forming dielectric ceramics, characterized in that, Compounds containing a perovskite (ABO3) type complex oxide and bonds represented by the following formula (1), ， The compound having the bond represented by formula (1) is selected from at least one of amide compounds, urea compounds, and imide compounds. The amide compound is a compound represented by the following formula (2), In equation (2) shown, R 1 R 2 and R 3 The substituents are independently selected from H, alkyl groups with or without substituents, and aryl groups with or without substituents, wherein the substituents are alkyl or halogens. The urea compound is a compound represented by the following formula (3), In equation (3) shown, R 1 R 2 R 3 and R 4 The substituents are independently selected from H, alkyl groups with or without substituents, and aryl groups with or without substituents, wherein the substituents are alkyl or halogens. The imide compound is a compound represented by the following formula (4), In equation (4) shown, R 1 R 2 and R 3 The substituents are independently selected from H, alkyl groups with or without substituents, and aryl groups with or without substituents, wherein the substituents are alkyl or halogens. The content of the compound having bonds represented by general formula (1) is 0.40 mol% to 80 mol% relative to the perovskite (ABO3) type composite oxide of the raw material.

2. The composition for forming dielectric ceramics as claimed in claim 1, characterized in that, The compound having the bonds represented by general formula (1) is the urea compound represented by formula (3).

3. The composition for forming dielectric ceramics as described in claim 1 or 2, characterized in that, It also contains hydroxy acids. The content of the hydroxy acid is 0.010 mol% to 20 mol% relative to the raw material perovskite (ABO3) type composite oxide.

4. The composition for forming dielectric ceramics as described in claim 1 or 2, characterized in that, It also contains compounds comprising the A-site element of the aforementioned perovskite (ABO3) type complex oxide. The content of the compound containing the A-site element is 0.10 mol% to 20 mol% relative to the raw material perovskite (ABO3) type composite oxide.

5. The composition for forming dielectric ceramics as described in claim 4, characterized in that, The compound containing the A-site element is at least one selected from the group consisting of hydroxides, chlorides, nitrates, acetates, oxides, and carbonates of Ba, Ca, Mg, or Sr.

6. The composition for forming dielectric ceramics as described in claim 1 or 2, characterized in that, The A-site element of the raw material perovskite (ABO3) type composite oxide is selected from at least one of Ba, Ca, Mg and Sr, and the B-site element is selected from at least one of Ti and Zr.

7. The composition for forming dielectric ceramics as claimed in claim 1, characterized in that, The compound having a bond represented by general formula (1) is selected from at least one of urea, methylurea, ethylurea, butylurea, acetylurea, acetamide, formamide, propionamide, butylamide, diacetamide, succinamide, ε-caprolactam, acetanilide, nicotinamide and stearamide.

8. The composition for forming dielectric ceramics as described in claim 3, characterized in that, The hydroxy acid is selected from at least one of citric acid, tartaric acid, malic acid, glycolic acid, lactic acid, glyceric acid, hydroxybutyric acid, isocitric acid, succinic acid, mevalonic acid, pantothenic acid, ricinoleic acid, and salicylic acid.

9. A dielectric ceramic material, characterized in that, It is a fired product of the dielectric ceramic forming composition according to any one of claims 1 to 8.

10. The dielectric ceramic material as described in claim 9, characterized in that, The firing temperature of the composition for forming dielectric ceramics is below 1000°C.

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