Additive for producing dielectric ceramics, and dielectric ceramics

Abstract

To provide an additive for producing dielectric ceramics which can easily realize a state of atomized powder, has low hygroscopicity, and can realize high density of dielectric ceramics.SOLUTION: An additive for producing dielectric ceramics is a composite powder comprising an alkaline earth metal element A and boron, and in the composite powder, the molar amount a of the alkaline earth metal element A and the molar amount b of the boron satisfy the following formula (1). The composite powder satisfies at least one condition selected from the group consisting of the following condition (i) and the following condition (ii). (i) The composite powder includes an amorphous phase. (ii) The composite powder includes two or more crystal phases.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an additive for producing dielectric ceramics and to dielectric ceramics. [Background technology]

[0002] In recent years, multilayer ceramic capacitors (MLCCs) have become smaller and / or thinner. As MLCCs become smaller and / or thinner, there is an increasing demand for further finer particle size of not only the dielectric powder raw material but also the sintering aids and other additives.

[0003] In the ceramics field, various sintering aids have been investigated.

[0004] Patent Document 1 discloses that a sintering aid containing boron oxide as a main component is used as one type of sintering aid in the production of MLCC.

[0005] Non-Patent Document 1 discloses that, with regard to a sintered body obtained by firing a composition containing barium titanate, by adding 1 to 3 mol% of BaB2O4 as a sintering aid to barium titanate and firing the resulting sintered body, the sintered body exhibits sufficient density even when fired at a lower firing temperature than when no sintering aid is added, the sintered body becomes semiconducting even when fired at a lower firing temperature than when no sintering aid is added, and the resulting sintered body has good mechanical strength.

[0006] Non-Patent Document 2 discloses a method for producing BaB2O4, in which single-crystal barium polyborate Ba3B6O9(OH)6 (BBOH) nanorods are synthesized using a low-temperature, organic-free hydrothermal technique, and β-BaB2O4 (BBO) nanospindles are realized by annealing the BBOH nanorods at a relatively low temperature of 810°C. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-196565 [Non-patent literature]

[0008] [Non-Patent Document 1] Sinterability and Electrical and Mechanical Properties of BaB2O4-Doped Barium Titanate, Nobuyuki Takeuchi, Yuji Yamazaki, Shingo Ishida, Materials (J. Soc. Mat. Sci., Japan), Vol.51, No.11, pp. 1267-1270, Nov. 2002 [Non-patent document 2] Low Temperature, Organic-Free Synthesis of Ba3B6O9(OH)6 Nanorods and β-BaB2O4 Nanospindles, Rui Li, Xinyong Tao and Xiaodong Li, J. Mater. Chem., 2009, 19, 983-987 Summary of the Invention [Problem to be solved by the invention]

[0009] Boron oxide powder is known as an additive for producing dielectric ceramics, including as a sintering aid in the production of MLCCs. However, further micronization of boron oxide powder is difficult, and attempts to further micronize boron oxide powder result in a significant decrease in productivity. Furthermore, using boron oxide powder as an additive for producing dielectric ceramics can lead to variations in the quality of the resulting dielectric ceramics.

[0010] An object of the present invention is to provide an additive for producing dielectric ceramics that can be easily produced in a finely divided powder state, has low hygroscopicity, and can produce high-density dielectric ceramics. Another object of the present invention is to provide a dielectric ceramic obtained from a composition containing the additive for producing dielectric ceramics. [Means for solving the problem]

[0011] As a result of extensive research, the present inventors have discovered a substance that functions as an additive for producing dielectric ceramics, has low hygroscopicity, and can be easily microparticulated. Based on this, the present inventors have discovered a method for achieving high density in dielectric ceramics obtained from a composition containing microparticulated powder, thereby completing the present invention.

[0012] One aspect of the present invention for solving at least one of the above problems relates to the following additive for producing dielectric ceramics.

[0013] An additive for producing dielectric ceramics, which is a composite powder containing an alkaline earth metal element A and boron, In the composite powder, the molar amount a of the alkaline earth metal element A and the molar amount b of the boron are expressed by the following formula (1):

[0014]

number

[0015] Fulfilling The composite powder satisfies at least one condition selected from the group consisting of the following condition (i) and the following condition (ii): Condition (i) The composite powder contains an amorphous phase; Condition (ii) The composite powder contains two or more types of crystal phases; Additive for manufacturing dielectric ceramics. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide an additive for producing dielectric ceramics that can easily be made into a finely divided powder state, has low hygroscopicity, and can achieve high density of dielectric ceramics. Also, according to the present invention, it is possible to provide a dielectric ceramic obtained from a composition containing the additive for producing dielectric ceramics. [Brief explanation of the drawings]

[0017] [Figure 1] 1 shows charts obtained by X-ray diffraction of sintering aids S1 to S3 for producing dielectric ceramics according to one embodiment of the present invention, boric acid as a raw material, and barium hydroxide as a raw material. [Figure 2] 1 shows charts obtained by X-ray diffraction of sintering aids S1 to S3 for producing dielectric ceramics according to one embodiment of the present invention, Ba3(B3O6)2 crystal, BaB8O13 crystal, and Ba3B6O11(OH)2 crystal. [Figure 3] 1 shows an SEM image of a sintering aid S1 for producing dielectric ceramics according to one embodiment of the present invention. [Figure 4] 1 shows an SEM image of a sintering aid S2 for producing dielectric ceramics according to one embodiment of the present invention. [Figure 5] 1 shows an SEM image of a sintering aid S5 (boron oxide powder) for producing dielectric ceramics according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments and can be modified in various ways within the scope of the claims. The embodiments described in this specification can be arbitrarily combined to form other embodiments. In this specification, the range "X to Y" means "X or more and Y or less." Unless otherwise specified, operations and measurements of physical properties are performed at room temperature (20 to 25°C) and a relative humidity of 40 to 50% RH.

[0019] One aspect of the present invention is an additive for producing dielectric ceramics, which is a composite powder containing an alkaline earth metal element A and boron (B), In the composite powder, the molar amount a of the alkaline earth metal element A and the molar amount b of the boron (B) are expressed by the following formula (1):

[0020]

number

[0021] Fulfilling The composite powder satisfies at least one condition selected from the group consisting of the following condition (i) and the following condition (ii): Condition (i) The composite powder contains an amorphous phase; Condition (ii) The composite powder contains two or more types of crystal phases; This relates to additives for producing dielectric ceramics.

[0022] The present inventors speculate that the mechanism by which the additive for producing dielectric ceramics according to this embodiment can solve the above problems is as follows.

[0023] Boron oxide powder, a conventional additive for producing dielectric ceramics, is generally produced by melting boric acid at high temperatures and solidifying the molten glass. The production of boron oxide powder involves a thermal history above the melting point of boron oxide, which necessitates pulverization of the solidified glass-like product, making microparticulation difficult. Furthermore, boron oxide is highly hygroscopic and easily reacts with moisture in the air to convert to boric acid. Therefore, when boron oxide powder is used as an additive for producing dielectric ceramics, the quality of the resulting dielectric ceramics tends to vary. Furthermore, the increased surface area resulting from microparticulation makes moisture absorption more likely, so when microparticulated boron oxide powder is used as an additive for producing dielectric ceramics, the quality of the resulting dielectric ceramics tends to vary.

[0024] On the other hand, composite powders containing an alkaline earth metal element A and boron (B) can generally be produced by a coprecipitation method. Some coprecipitation methods can produce a product without undergoing a thermal history above the melting point of the product. In such a method, a product in a state where primary particles are aggregated is obtained, which makes it easy to atomize the product by crushing. Therefore, the additive for producing dielectric ceramics according to this embodiment can easily produce a finely atomized powder.

[0025] In the composite powder containing alkaline earth metal element A and boron (B), the molar amount a of alkaline earth metal element A and the molar amount b of boron (B) satisfy the relationship of formula (1).

[0026] When a / (a+b) is less than 3 / 5, the composite powder containing alkaline earth metal element A and boron (B) is considered to be substantially free of an oxide phase of alkaline earth metal element A. The oxide of alkaline earth metal element A generally functions insufficiently or does not function at all as an additive for producing dielectric ceramics, such as a sintering aid. Since the composite powder containing alkaline earth metal element A and boron (B) is substantially free of an oxide phase of alkaline earth metal element A, the deterioration of the additive's function as an additive for producing dielectric ceramics, due to the presence of the oxide phase of alkaline earth metal element A, is suppressed. As a result, high density dielectric ceramics can be produced from compositions containing the additive for producing dielectric ceramics.

[0027] When a / (a+b) is greater than 1 / 9, the composite powder containing the alkaline earth metal element A and boron (B) is considered to be substantially free of a boron oxide phase. Since the composite powder containing the alkaline earth metal element A and boron (B) is substantially free of a boron oxide phase, an increase in hygroscopicity can be suppressed even if the surface area of the composite powder increases due to microparticulation.

[0028] Furthermore, the composite powder containing an alkaline earth metal element A and boron (B) satisfies at least one condition selected from the group consisting of condition (i) and condition (ii). When the composite powder containing an alkaline earth metal element A and boron (B) contains an amorphous phase and / or two or more types of crystalline phases, it is easy to achieve a finely divided powder state.

[0029] The above mechanism is based on speculation, and its correctness does not affect the technical scope of the present invention. Similarly, the correctness of other speculations in this specification does not affect the technical scope of the present invention.

[0030] In this specification, the term "composite powder containing an alkaline earth metal element A and boron (B)" refers to a powder that is substantially composed of particles containing both the alkaline earth metal element A and boron (B). Therefore, the "composite powder containing an alkaline earth metal element A and boron (B)" is different from a mixed powder of a "powder containing an alkaline earth metal element A" and a "powder containing boron (B)."

[0031] In scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS) point analysis, when both alkaline earth metal element A and boron (B) are confirmed in the analysis results of 90 or more particles out of 100 particles selected from the powder to be measured, the powder to be measured can be determined to be a composite powder containing alkaline earth metal element A and boron (B). Preferably, both alkaline earth metal element A and boron (B) are confirmed in the analysis results of 95 or more particles out of 100 particles selected from the powder to be measured. More preferably, both alkaline earth metal element A and boron (B) are confirmed in the analysis results of 99 or more particles out of 100 particles selected from the powder to be measured. It is particularly preferred that both alkaline earth metal element A and boron (B) are confirmed in the analysis results of 100 particles selected from the powder to be measured.

[0032] In one embodiment, details of scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS) spot analysis are provided in the Examples.

[0033] The alkaline earth metal element A is not particularly limited and includes beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). These alkaline earth metal elements A may be used alone or in combination of two or more. The alkaline earth metal element A may contain at least one element selected from the group consisting of the alkaline earth metal elements exemplified above. The alkaline earth metal element A preferably contains at least one element selected from the group consisting of beryllium (Be), magnesium (Mg), strontium (Sr), and barium (Ba), more preferably contains at least one element selected from the group consisting of strontium (Sr) and barium (Ba), even more preferably contains barium (Ba), and particularly preferably consists solely of barium (Ba). The alkaline earth metal element A may be an alkaline earth metal element other than calcium (Ca).

[0034] The composite powder containing an alkaline earth metal element A and boron (B) preferably further contains oxygen (O) in addition to the alkaline earth metal element A and boron (B). The compound containing both the alkaline earth metal element A and boron (B) that can be contained in the composite powder containing an alkaline earth metal element A and boron (B) is not particularly limited. When the alkaline earth metal element A is barium (Ba), the compound containing both the alkaline earth metal element A and boron (B) is Ba3(B3O6)2, BaBO 13 , BaB4O7, BaB2O 4、 Ba3B2O6 and Ba3B6O 11 (OH)2. When the alkaline earth metal element A is strontium (Sr), the compound containing both the alkaline earth metal element A and boron (B) is SrBO. 10It is preferable that the material contains at least one compound selected from the group consisting of SrB4O7, SrB2O4, Sr2B2O5 and Sr3B2O6.

[0035] The contents of the alkaline earth metal element A and boron (B) in the composite powder containing the alkaline earth metal element A and boron (B) are not particularly limited as long as they satisfy the relationship of the above formula (1). In the composite powder containing the alkaline earth metal element A and boron (B), the molar amount a of the alkaline earth metal element A and the molar amount b of boron (B) preferably satisfy the following formula (2), and more preferably satisfy the following formula (3).

[0036]

number

[0037] When the composite powder contains two or more kinds of alkaline earth metal elements A, the molar amount a of the alkaline earth metal elements A refers to the total amount thereof.

[0038] The types and amounts of elements contained in the composite powder can be measured by ICP atomic emission spectroscopy (inductively coupled plasma atomic emission spectroscopy). In one embodiment, details of ICP atomic emission spectroscopy are described in the Examples.

[0039] The composite powder containing an alkaline earth metal element A and boron (B) satisfies at least one condition selected from the group consisting of condition (i) and condition (ii): Condition (i) The composite powder contains an amorphous phase; Condition (ii) The composite powder contains two or more types of crystal phases.

[0040] In the condition (i), it is preferable that the composite powder containing the alkaline earth metal element A and boron (B) does not contain a crystalline phase.

[0041] The composite powder containing an alkaline earth metal element A and boron (B) preferably satisfies condition (i) or condition (ii), more preferably satisfies condition (i), and even more preferably satisfies condition (i) and does not contain a crystalline phase.

[0042] Whether or not the composite powder containing an alkaline earth metal element A and boron (B) satisfies the condition (i) and / or the condition (ii) can be determined by analysis using an X-ray diffraction method (XRD method).

[0043] In this specification, when a Rietveld analysis is performed on the results of X-ray diffraction measurement using the analysis software provided with the X-ray diffractometer, and two or more crystalline phases of a compound containing both an alkaline earth metal element A and boron (B) are confirmed, which account for 5% by mass or more of the total amount (100% by mass) of the crystalline phases shown as candidates in the analysis software, it can be determined that the powder containing an alkaline earth metal element A and boron (B) contains two or more types of crystalline phases.

[0044] In this specification, if a broad peak (halo pattern) with a peak width of 5° or more in 2θ is confirmed in a chart obtained by X-ray diffraction measurement, the powder containing an alkaline earth metal element A and boron (B) is considered to contain an amorphous phase. When a halo pattern is confirmed in a chart obtained by X-ray diffraction measurement of a composite powder containing an alkaline earth metal element A and boron (B), it is preferable to confirm the presence of broad peaks with a peak width of 5° or more in 2θ at positions near 27° (in the range of 27°±4°) and near 2θ at positions near 43° (in the range of 43°±4°), or to confirm the presence of broad peaks with a peak width of 5° or more in 2θ at positions near 29° (in the range of 29°±8°) and near 46° (in the range of 46°±6°). When a halo pattern is observed in a chart obtained by X-ray diffraction measurement of a composite powder containing an alkaline earth metal element A and boron (B), it is more preferable to confirm the presence of broad peaks with a peak width of 5° or more in 2θ at a position where 2θ is approximately 27° (within the range of 27°±4°) and at a position where 2θ is approximately 43° (within the range of 43°±4°).

[0045] In one embodiment of the additive for producing dielectric ceramics, a halo pattern is observed in the chart obtained by X-ray diffraction measurement of a composite powder containing an alkaline earth metal element A and boron (B), and when the results of the X-ray diffraction measurement of the composite powder containing an alkaline earth metal element A and boron (B) are subjected to Rietveld analysis in the analysis software provided with the X-ray diffractometer, it is preferable that no crystalline phase of a compound containing both the alkaline earth metal element A and boron (B) is observed, accounting for 5 mass% or more of the total amount (100 mass%) of the crystalline phases shown as candidates on the analysis software.

[0046] In this specification, when the Rietveld analysis in the analysis software attached to the X-ray diffraction device is performed on the results of X-ray diffraction measurement, a crystalline phase of a compound containing both an alkaline earth metal element A and boron (B) that accounts for 5 mass% or more of the total amount (100 mass%) of the crystalline phases shown as candidates on the analysis software is not confirmed; No clear peaks other than the halo pattern are observed in the chart obtained by X-ray diffraction measurement. If the above condition is satisfied, the powder containing the alkaline earth metal element A and boron (B) is determined to contain no crystalline phase.

[0047] In one embodiment, an additive for producing a dielectric ceramic is a composite powder containing an alkaline earth metal element A and boron (B), In the composite powder, the molar amount a of the alkaline earth metal element A and the molar amount b of the boron (B) satisfy the above formula (1), The composite powder satisfies at least one condition selected from the group consisting of the following condition (i-2) and the following condition (ii-2): Condition (i-2) A halo pattern is confirmed in the composite powder by X-ray diffraction measurement. Condition (ii-2) When a Rietveld analysis is performed on the results of X-ray diffraction measurement of the composite powder, two or more crystalline phases of a compound containing both an alkaline earth metal element A and boron (B) are confirmed, accounting for 5 mass% or more of the total amount (100 mass%) of crystalline phases. Additives for manufacturing dielectric ceramics are also included. The total amount of crystalline phases in the above condition (ii-2) refers to the total amount of crystalline phases shown as candidates on the analysis software. In this embodiment, the composite powder containing an alkaline earth metal element A and boron (B) preferably satisfies condition (i-2) or condition (ii-2), and more preferably satisfies condition (i-2). It is more preferable that the composite powder containing an alkaline earth metal element A and boron (B) satisfies condition (i-2), and when the Rietveld analysis in the analysis software attached to the X-ray diffraction device is performed on the X-ray diffraction measurement results of the composite powder containing an alkaline earth metal element A and boron (B), a crystalline phase of a compound containing both an alkaline earth metal element A and boron (B) that accounts for 5 mass% or more of the total amount (100 mass%) of crystalline phases shown as candidates on the analysis software is not confirmed. The composite powder containing an alkaline earth metal element A and boron (B) satisfies condition (i-2), Regarding the X-ray diffraction measurement results of a composite powder containing alkaline earth metal element A and boron (B), when Rietveld analysis was performed using the analysis software attached to the X-ray diffractometer, no crystalline phase of a compound containing both alkaline earth metal element A and boron (B) was confirmed, accounting for 5% by mass or more of the total amount (100% by mass) of the crystalline phases shown as candidates in the analysis software; and No clear peaks other than the halo pattern are observed in the chart obtained by X-ray diffraction measurement. It is particularly preferable that the following conditions are further satisfied.

[0048] As the X-ray diffraction device, a desktop X-ray diffraction device MiniFlex (registered trademark) 600 manufactured by Rigaku Corporation can be used, and as the analysis software, integrated powder X-ray analysis software PDXL (manufactured by Rigaku Corporation) that comes with the desktop X-ray diffraction device MiniFlex (registered trademark) 600 manufactured by Rigaku Corporation can be used.

[0049] In one embodiment, for a composite powder containing an alkaline earth metal element A and boron (B), it is preferable that no peaks of the raw materials are observed in the X-ray diffraction pattern obtained by analysis using an X-ray diffraction method (XRD method). For example, for a composite powder containing an alkaline earth metal element A and boron (B), it is preferable that no peaks of the raw material compound containing the alkaline earth metal element A and the raw material compound containing boron (B) are observed in the X-ray diffraction pattern obtained by analysis using an X-ray diffraction method (XRD method).

[0050] In one embodiment, details of the analysis by X-ray diffraction (XRD) method are described in the Examples.

[0051] Average primary particle size L of composite powder containing alkaline earth metal element A and boron (B) A is not particularly limited. The average primary particle diameter L of the composite powder containing an alkaline earth metal element A and boron (B) A is preferably 0.001 μm or more, more preferably 0.005 μm or more, even more preferably 0.01 μm or more, even more preferably 0.05 μm or more, and particularly preferably 0.1 μm or more. Within these ranges, a composite powder in which the alkaline earth metal element A and boron (B) are more uniformly composited can be produced. The average primary particle diameter L of the composite powder containing the alkaline earth metal element A and boron (B) A is preferably less than 10.0 μm, more preferably 5.0 μm or less, even more preferably 2.0 μm or less, even more preferably 1.0 μm or less, even more preferably 0.5 μm or less, even more preferably 0.4 μm or less, even more preferably 0.3 μm or less, and particularly preferably 0.2 μm or less (lower limit above 0 μm). Within these ranges, it becomes easier to uniformly mix the additive for producing dielectric ceramics into the dielectric powder. The average primary particle diameter L of the composite powder containing an alkaline earth metal element A and boron (B) APreferred ranges of are, for example, 0.001 μm or more and less than 10.0 μm, 0.005 μm or more and 5.0 μm or less, 0.01 μm or more and 2.0 μm or less, 0.05 μm or more and 0.5 μm or less, 0.1 μm or more and 0.5 μm or less, 0.1 μm or more and 0.4 μm or less, 0.1 μm or more and 0.3 μm or less, and 0.1 μm or more and 0.2 μm or less. However, the average primary particle diameter L of the composite powder containing an alkaline earth metal element A and boron (B) is A The range is not limited to these.

[0052] Average primary particle size L of composite powder containing alkaline earth metal element A and boron (B) A can be measured and calculated by observing a composite powder containing an alkaline earth metal element A and boron (B) with a scanning electron microscope (SEM). Specifically, it can be measured and calculated by the following method. SEM observation is performed on a composite powder containing an alkaline earth metal element A and boron (B), and 20 primary particles are randomly selected from the primary particles in the obtained SEM image. Next, 5 primary particles from the side with the largest primary particle diameter and 5 primary particles from the side with the smallest primary particle diameter are removed from the selected 20 primary particles, leaving 10 primary particles. Thereafter, the average value of the primary particle diameters of the selected 10 primary particles is calculated, and the calculated average value is used as the average primary particle diameter L of the composite powder containing an alkaline earth metal element A and boron (B). A Let's say.

[0053] Average primary particle size L of composite powder containing alkaline earth metal element A and boron (B) A The details of the measurement method are described in the Examples.

[0054] The mass gain rate of a composite powder containing an alkaline earth metal element A and boron (B) after 6 hours is not particularly limited, but the smaller the better. The mass gain rate of a composite powder containing an alkaline earth metal element A and boron (B) after 6 hours is preferably less than 3.0%, more preferably less than 1.0% (lower limit 0%). A small mass gain rate of a composite powder containing an alkaline earth metal element A and boron (B) indicates that the composite powder containing an alkaline earth metal element A and boron (B) has low hygroscopicity. The mass gain rate of a composite powder containing an alkaline earth metal element A and boron (B) after 6 hours can be calculated using the following formula.

[0055]

number

[0056] The mass increase rate of a composite powder containing an alkaline earth metal element A and boron (B) after 6 hours can be measured by TG-DTA (simultaneous differential thermal analysis). A TG-DTA 2020SA manufactured by NETZSH can be used as the measuring device. Details of the measurement method are described in the Examples.

[0057] (Method for manufacturing additives for manufacturing dielectric ceramics) The method for producing a composite powder containing an alkaline earth metal element A and boron (B) is not particularly limited. Composite powders containing an alkaline earth metal element A and boron (B) are generally produced by a coprecipitation method. The above-mentioned additive for producing dielectric ceramics is preferably produced by a coprecipitation method. Another aspect of the present invention can be said to relate to a method for producing an additive for producing dielectric ceramics according to the above-mentioned aspect by a coprecipitation method. The coprecipitation method is not particularly limited, but examples include a method comprising simultaneously precipitating hydroxides and / or hydrates thereof containing two or more metal cations from an aqueous solution containing two or more metal cations. A preferred example of the coprecipitation method includes a method comprising simultaneously precipitating hydroxides and / or hydrates thereof containing two or more metal cations by adjusting the pH of an aqueous solution containing two or more metal cations. A more preferred example of the coprecipitation method includes a method comprising simultaneously precipitating hydroxides and / or hydrates thereof containing two or more metal cations by adjusting the pH of an aqueous solution containing two or more metal cations to minimize their solubility products. However, the coprecipitation method applicable to the method for producing a composite powder containing an alkaline earth metal element A and boron (B) is not limited to these methods.

[0058] The method for producing a composite powder containing an alkaline earth metal element A and boron (B) by the coprecipitation method is not particularly limited, but for example, it may be possible to prepare a raw material solution 1 containing boric acid and a solvent (for example, water, preferably ion-exchanged water) and a raw material solution 2 containing a hydroxide and / or a hydrate of an alkaline earth metal element A and a solvent (for example, water, preferably ion-exchanged water); heat the raw material solutions 1 and 2; mix the heated raw material solutions 1 and 2, and then cool them to obtain an alkaline earth metal Examples of production methods include obtaining a precipitate (co-precipitate) containing element A and boron (B); subjecting the obtained precipitate to solid-liquid separation, followed by drying the obtained precipitate (cake-like precipitate); optionally crushing the dried powder; calcining the dried powder (or the crushed powder if the dried powder is crushed) to obtain a powder (a composite powder containing alkaline earth metal element A and boron (B)); and optionally crushing the obtained powder (a composite powder containing alkaline earth metal element A and boron (B)). The calcination temperature when calcining the dried powder (or the crushed powder if the dried powder is crushed) to obtain a powder (a composite powder containing alkaline earth metal element A and boron (B)) is preferably below the melting point of the product.

[0059] Raw material solution 1 and raw material solution 2 contain a solvent. The solvent is not particularly limited and may be, for example, an organic solvent, water, or a combination thereof. The solvent preferably contains water, and more preferably consists of water alone. When raw material solution 1 contains water, the content of boric acid in raw material solution 1 is not particularly limited, but is preferably 6.0 g to 30.0 g, more preferably 10.0 g to 20.0 g, per 100 g of water. When raw material solution 2 contains water, the content of alkaline earth metal element A in raw material solution 2 is not particularly limited, but is preferably 1.0 g to 100.0 g, per 100 g of water. When raw material solution 2 contains water, the content of barium (Ba) in raw material solution 2 is not particularly limited, but is preferably 3.0 g to 100.0 g, more preferably 10.0 g to 80.0 g, and even more preferably 11.0 g to 80.0 g, per 100 g of water. When the raw material solution 2 contains water, the content of strontium (Sr) in the raw material solution 2 is not particularly limited, but is preferably 2.0 g or more and 90.0 g or less, and more preferably 4.0 g or more and 40.0 g or less, per 100 g of water.

[0060] It is particularly preferred that raw material solution 1 and raw material solution 2 are mixed in a ratio that results in a composite powder containing alkaline earth metal element A and boron (B), with the desired molar amount a of alkaline earth metal element A and the desired molar amount b of boron (B). Raw material solution 1 and raw material solution 2 are mixed in a ratio such that the value calculated by the relationship a' / (a'+b') between the molar amount b' of boron (B) in raw material solution 1 and the molar amount a' of alkaline earth metal element A in raw material solution 2 is greater than 1 / 9 and less than 3 / 5, more preferably greater than 1 / 9 and less than 1 / 2, and even more preferably greater than 1 / 5 and less than 1 / 2. When raw material solution 2 contains two or more alkaline earth metal elements A, the molar amount a' of the alkaline earth metal elements A refers to the total amount thereof. Heating may be performed during the preparation of raw solution 1 and raw solution 2. The heating temperature during the preparation of raw solution 1 and raw solution 2 is not particularly limited, but is preferably 50°C or higher and 90°C or lower. The method for solid-liquid separation of the precipitate is not particularly limited, but examples include filtration using a Nutsche filter and filter paper. The drying temperature during drying of the precipitate after solid-liquid separation is not particularly limited, but is preferably 70°C or higher and 120°C or lower. The drying time during drying of the precipitate after solid-liquid separation is not particularly limited, but is preferably 3 hours or higher and 24 hours or lower. The precipitate can be dried using, for example, a dryer. The firing temperature during calcination of the dried precipitate is not particularly limited, but is preferably 200°C or higher and 600°C or lower, more preferably 250°C or higher and 500°C or lower, even more preferably 300°C or higher and 450°C or lower, and particularly preferably 350°C or higher and 400°C or lower. The firing temperature during calcination of the dried precipitate is not particularly limited, but is preferably a temperature below the melting point of the product. The calcination temperature for calcining the dried precipitate is not particularly limited, but is preferably 1 hour to 10 hours, more preferably 3 hours to 10 hours. The calcination of the dried precipitate can be carried out, for example, using a calcination furnace. The method for crushing the precipitate and powder is not particularly limited, but examples thereof include a crushing method using a mortar, a crushing method using a ball mill or a bead mill, etc.The crushing method using a ball mill is not particularly limited, but examples thereof include crushing methods using a dry bead mill. The type of ball is not particularly limited, but examples thereof include polyethylene balls and zirconia balls. The ball diameter is not particularly limited, but may be, for example, 1 mm or more and 10 mm or less. The mixing time is not particularly limited, but may be, for example, 1 hour or more and 50 hours or less.

[0061] The alkaline earth metal element A in the method for producing a composite powder containing an alkaline earth metal element A and boron (B) is described in the same manner as the alkaline earth metal element A in the additive for producing dielectric ceramics. The hydroxide or hydrate of the alkaline earth metal element A is not particularly limited, but examples thereof include strontium hydroxide, strontium hydroxide hydrate, and barium hydroxide. The hydroxide or hydrate of the alkaline earth metal element A may be a single type or a combination of two or more types. The hydroxide or hydrate of the alkaline earth metal element A may contain at least one compound selected from the group consisting of the compounds exemplified above. The hydroxide or hydrate of the alkaline earth metal element A is preferably at least one compound selected from the group consisting of strontium hydroxide, strontium hydroxide hydrate, and barium hydroxide, more preferably at least one compound selected from the group consisting of strontium hydroxide hydrate and barium hydroxide, and even more preferably barium hydroxide. The hydrate of strontium hydroxide is not particularly limited, but examples thereof include strontium hydroxide octahydrate.

[0062] (Use of additives for manufacturing dielectric ceramics, dielectric ceramics and manufacturing method thereof) The composite powder containing an alkaline earth metal element A and boron (B) is preferably used in an application that includes mixing with a dielectric powder.The composite powder containing an alkaline earth metal element A and boron (B) is preferably used as an additive for producing dielectric ceramics in an application that includes mixing with a dielectric powder.

[0063] The additive for producing dielectric ceramics is preferably used as a sintering aid.The additive for producing dielectric ceramics is preferably a sintering aid for producing dielectric ceramics.

[0064] The method of using the additive for producing dielectric ceramics is not particularly limited. For example, the additive for producing dielectric ceramics may be mixed in advance with other additives as other components, and used for producing dielectric ceramics in the form of an additive composition for producing dielectric ceramics containing these additives.

[0065] The mixing ratio of the dielectric powder and the additive for producing a dielectric ceramic is not particularly limited. The amount of the additive for producing a dielectric ceramic is preferably 0.01 mol or more per 100 mol of the dielectric powder, more preferably 0.1 mol or more per 100 mol of the dielectric powder, and even more preferably 1 mol or more per 100 mol of the dielectric powder. Within these ranges, the density of the dielectric ceramic produced from the composition containing the dielectric powder and the additive for producing a dielectric ceramic may be further improved. The amount of the additive for producing a dielectric ceramic is preferably 10 mol or less per 100 mol of the dielectric powder, more preferably 5 mol or less per 100 mol of the dielectric powder, and even more preferably 3 mol or less per 100 mol of the dielectric powder (the lower limit is more than 0 mol per 100 mol of the dielectric powder). Within these ranges, the dielectric ceramic produced from the composition containing the dielectric powder and the additive for producing a dielectric ceramic may be more uniform and have fewer defect structures. Preferred ranges of the amount of additive for producing dielectric ceramics include, for example, 0.01 mol or more and 10 mol or less per 100 mol of dielectric powder, 0.1 mol or more and 5 mol or less per 100 mol of dielectric powder, and 1 mol or more and 3 mol or less per 100 mol of dielectric powder, but the amount range of additive for producing dielectric ceramics is not limited to these.

[0066] The method for producing a dielectric ceramic is not particularly limited, and examples thereof include a method comprising sintering a composition containing the additive for producing a dielectric ceramic according to the above embodiment and a dielectric powder, such as the following dielectric ceramic production method 1 and the following dielectric ceramic production method 2. Another embodiment of the present invention can also be said to relate to a dielectric ceramic obtained by sintering a composition containing the additive for producing a dielectric ceramic according to the above embodiment and a dielectric powder.

[0067] Manufacturing method 1 of dielectric ceramics: A manufacturing method comprising: molding a composition containing a dielectric powder and an additive for manufacturing dielectric ceramics to obtain a molded composition (e.g., a pellet-shaped composition); and firing the molded composition to obtain a sintered body (dielectric ceramics).

[0068] Manufacturing method 2 of dielectric ceramics: A manufacturing method comprising: applying a slurry containing a dielectric powder, an additive for manufacturing a dielectric ceramics, and a solvent, and drying the slurry to obtain a sheet-like composition containing the dielectric powder and the additive for manufacturing a dielectric ceramics (sheet-like composition); and firing the obtained sheet-like composition to obtain a sintered body (dielectric ceramics).

[0069] The dielectric ceramic manufacturing method 1 may further include obtaining a slurry containing a dielectric powder, an additive for producing a dielectric ceramic, and a solvent, and drying the obtained slurry to obtain a composition containing the dielectric powder and the additive for producing a dielectric ceramic. The dielectric ceramic manufacturing method 1 and the dielectric ceramic manufacturing method 2 may further include producing a slurry containing a dielectric powder, an additive for producing a dielectric ceramic, and a solvent. The slurry containing a dielectric powder, an additive for producing a dielectric ceramic, and a solvent is preferably produced by a method including mixing the dielectric powder, the additive for producing a dielectric ceramic, and the solvent.

[0070] The solvent in the slurry containing the dielectric powder, the additive for producing a dielectric ceramic, and the solvent is not particularly limited, and any known solvent can be used. Examples of the solvent include alcohols such as ethanol; ethers; esters; aromatic hydrocarbons such as toluene and xylene; and aliphatic hydrocarbons. The solvent may be a single solvent or a combination of two or more solvents. The solvent may contain at least one compound selected from the group consisting of the compounds exemplified above. The solvent preferably contains alcohol, and more preferably contains ethanol.

[0071] The total content of the dielectric powder and the additives for producing dielectric ceramics in the slurry containing the dielectric powder, the additives for producing dielectric ceramics, and the solvent is not particularly limited, but is preferably 0.1 mass % or more and 50 mass % or less, more preferably 1 mass % or more and 25 mass % or less, and even more preferably 3 mass % or more and 15 mass % or less, relative to the total mass of the slurry.

[0072] The total content of the dielectric powder and the additives for producing a dielectric ceramic in a composition containing the dielectric powder and the additives for producing a dielectric ceramic to be fired is preferably 80% by mass or more and 100% by mass or less, more preferably 85% by mass or more and 100% by mass or less, even more preferably 90% by mass or more and 100% by mass or less, and particularly preferably 95% by mass or more and 100% by mass or less, relative to the total mass of the composition. The total content of the dielectric powder and the additives for producing a dielectric ceramic in a composition containing the dielectric powder and the additives for producing a dielectric ceramic to be fired may be in the range of 80% by mass or more and less than 100% by mass, 85% by mass or more and less than 100% by mass, 90% by mass or more and less than 100% by mass, or 95% by mass or more and less than 100% by mass, relative to the total mass of the composition.

[0073] In preparing a slurry containing a dielectric powder, a dielectric ceramic manufacturing additive, and a solvent, other components may or may not be further mixed. The slurry containing a dielectric powder, a dielectric ceramic manufacturing additive, and a solvent may or may not further contain other components. The composition containing a dielectric powder and a dielectric ceramic manufacturing additive may or may not further contain other components. The composition containing a dielectric powder and a dielectric ceramic manufacturing additive may or may not further contain other components. The other components are not particularly limited, but examples include a dispersant, a binder, a plasticizer, etc. In one embodiment, the other components preferably include at least one selected from the group consisting of a dispersant, a binder, and a plasticizer, and more preferably include a binder. The binder is not particularly limited, and examples thereof include polyvinyl alcohol (PVA), cellulose resins (e.g., methyl cellulose, ethyl cellulose, ethylhydroxyethyl cellulose, nitrocellulose, etc.), acrylic resins, and butyral resins (e.g., polyvinyl butyral). The binder may be a single type or a combination of two or more types. The binder may contain at least one compound selected from the group consisting of the compounds exemplified above. Among these, the binder preferably contains polyvinyl alcohol, and more preferably consists solely of polyvinyl alcohol. The content of the binder in the composition containing the dielectric powder and additives for producing a dielectric ceramic to be fired is not particularly limited, but is preferably 0.001% by mass or more and 10% by mass or less, more preferably 0.01% by mass or more and 1% by mass or less, and even more preferably 0.05% by mass or more and 0.5% by mass or less, relative to the total mass of the composition. When the composition containing the dielectric powder and additives for producing a dielectric ceramic contains two or more binders, the content of the binders refers to the total amount thereof. In preparing a slurry containing the dielectric powder, the additives for producing a dielectric ceramic, and the solvent, a dispersant and a plasticizer may or may not be further mixed.The slurry containing the dielectric powder, the additive for producing a dielectric ceramic, and the solvent may or may not further contain a dispersant and a plasticizer, respectively.

[0074] The mixing of the dielectric powder, the additives for producing dielectric ceramics, and other components as needed is not particularly limited, but is preferably carried out using, for example, a ball mill or a bead mill, and more preferably a wet bead mill. Furthermore, other components as needed may be mixed after the dielectric powder and the additives for producing dielectric ceramics are mixed. For example, the dielectric powder and the additives for producing dielectric ceramics may be mixed using a wet ball mill, and then other components as needed may be further mixed. The type of ball is not particularly limited, but examples include polyethylene balls and zirconia balls. The ball diameter is not particularly limited, but may be, for example, 1 mm or more and 10 mm or less. The solvent may be the same as the solvents listed above (solvents in the slurry containing the dielectric powder, the additives for producing dielectric ceramics, and the solvent). The mixing time is not particularly limited, but may be, for example, 1 hour or more and 10 hours or less.

[0075] There are no particular limitations on the method for drying the slurry containing the dielectric powder, additives for producing a dielectric ceramic, and solvent, or the coating film thereof, but it is preferable to use, for example, a rotary evaporator or a conveyor drying oven.

[0076] Before firing the composition containing the dielectric powder and the additives for producing dielectric ceramics, the composition containing the dielectric powder and the additives for producing dielectric ceramics may be pressed. Before firing the composition containing the dielectric powder and the additives for producing dielectric ceramics, the composition containing the dielectric powder and the additives for producing dielectric ceramics may be molded by a method including pressing to obtain a molded body, and the obtained molded body may then be sieved in powder form. The mesh size of the sieve is not particularly limited, but may be, for example, 100 μm or more and 1000 μm or less. The method of pressing is not particularly limited, but uniaxial pressing is preferred. The pressure during pressing is not particularly limited, but may be, for example, 0.10 MPa or more and 0.50 MPa or less.

[0077] The firing of the composition containing the dielectric powder and the additive for producing the dielectric ceramics is not particularly limited, but is preferably carried out using a firing furnace. For firing, it is preferable to use a container such as an alumina sagger. The firing conditions and firing method are not particularly limited. The firing temperature is preferably 800°C to 1500°C, more preferably 900°C to 1300°C, and even more preferably 1000°C to 1200°C. The firing time is preferably 1 hour to 20 hours, more preferably 3 hours to 15 hours, and even more preferably 5 hours to 10 hours.

[0078] The dielectric powder may be one type alone or a combination of two or more types.

[0079] The dielectric powder may contain an alkaline earth metal element A'. The dielectric powder preferably contains an alkaline earth metal element A'. Examples of the alkaline earth metal element A' include the same elements as those listed above as the alkaline earth metal element A. These alkaline earth metal elements A' may be one type alone or a combination of two or more types. The alkaline earth metal element A' may contain at least one element selected from the group consisting of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). In one embodiment, the alkaline earth metal element A' preferably contains at least one element selected from the group consisting of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba), more preferably contains at least one element selected from the group consisting of calcium (Ca), strontium (Sr), and barium (Ba), even more preferably contains barium (Ba), and particularly preferably consists solely of barium (Ba). The alkaline earth metal element A' may be an alkaline earth metal element other than calcium (Ca).

[0080] In one embodiment, the alkaline earth metal element A contained in the composite powder containing an alkaline earth metal element A and boron (B) and the alkaline earth metal element A' contained in the dielectric powder preferably contain at least one of the same element. More preferably, the alkaline earth metal element A contained in the composite powder containing an alkaline earth metal element A and boron (B) and the alkaline earth metal element A' contained in the dielectric powder both contain barium (Ba). When the dielectric ceramic-producing additive and the dielectric powder contain the same alkaline earth metal element, the density of the dielectric ceramic produced from the composition containing the dielectric powder and the additive for producing the dielectric ceramic may be further improved. This is presumably because the concentration gradient of the alkaline earth metal element between the inside and outside of the dielectric powder in the composition containing the dielectric powder and the additive for producing the dielectric ceramic is reduced, thereby suppressing the outflow of the alkaline earth metal from the dielectric powder and the diffusion of the alkaline earth metal element within the composition. It is speculated that such suppression of diffusion suppresses particle growth during sintering, particularly at low temperatures of around 1000°C, thereby increasing the density of the dielectric ceramic produced from a composition containing the dielectric powder and the additive for producing a dielectric ceramic. In one embodiment, the additive for producing a dielectric ceramic, which is a composite powder containing an alkaline earth metal element A and boron (B), is used in an application that includes mixing with a dielectric powder, and the dielectric powder contains an alkaline earth metal element A', and it is preferable that the alkaline earth metal element A and the alkaline earth metal element A' contain at least one element of the same type. A dielectric ceramic according to one embodiment is obtained by sintering a composition containing the additive for producing a dielectric ceramic, which is a composite powder containing an alkaline earth metal element A and boron (B) according to the above aspect, and a dielectric powder, and the dielectric powder contains an alkaline earth metal element A', and it is preferable that the alkaline earth metal element A and the alkaline earth metal element A' contain at least one element of the same type.

[0081] The dielectric powder may contain an element other than the alkaline earth metal element A'. The dielectric powder preferably contains an element other than the alkaline earth metal element A', and more preferably contains an element other than the alkaline earth metal element A' and the alkaline earth metal element A'. The element other than the alkaline earth metal element A' is not particularly limited, but preferably contains at least one element selected from the group consisting of typical elements and transition elements other than the alkaline earth metal element A'. Examples of typical elements other than the alkaline earth metal element A' include hydrogen (H), lithium (Li), zinc (Zn), boron (B), aluminum (Al), oxygen (O), silicon (Si), lead (Pb), phosphorus (P), and bismuth (Bi). These typical elements other than the alkaline earth metal element A' may be used alone or in combination of two or more. Examples of transition elements include titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), and rare earth elements. Examples of rare earth metals include 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), and yttrium (Y). These transition elements may be used alone or in combination of two or more. The elements other than the alkaline earth metal element A' may be used alone or in combination of two or more. The elements other than the alkaline earth metal element A' may include at least one element selected from the group consisting of the elements exemplified above.

[0082] The dielectric powder preferably contains at least one element selected from the group consisting of barium (Ba), strontium (Sr), calcium (Ca), zirconium (Zr), and titanium (Ti), more preferably at least one element selected from the group consisting of barium (Ba), strontium (Sr), zirconium (Zr), and titanium (Ti), even more preferably barium (Ba) and titanium (Ti), and particularly preferably barium (Ba), titanium (Ti), and oxygen (O). Specific examples of the dielectric powder include, but are not limited to, barium titanate (BaTiO), calcium zirconate (CaZrO), and the like. In one embodiment, the dielectric powder preferably contains at least one compound selected from the group consisting of barium titanate and calcium zirconate, more preferably barium titanate, and even more preferably barium titanate alone.

[0083] The additive for producing dielectric ceramics according to one embodiment is used in an application involving mixing with a dielectric powder, and the dielectric powder preferably contains at least one element selected from the group consisting of barium (Ba), strontium (Sr), calcium (Ca), zirconium (Zr), and titanium (Ti). The additive for producing dielectric ceramics according to one embodiment is used in an application involving mixing with a dielectric powder, and the dielectric powder more preferably contains at least one element selected from the group consisting of barium (Ba), strontium (Sr), zirconium (Zr), and titanium (Ti). The additive for producing dielectric ceramics according to one embodiment is used in an application involving mixing with a dielectric powder, and the dielectric powder more preferably contains barium (Ba) and titanium (Ti). The additive for producing dielectric ceramics according to one embodiment is used in an application involving mixing with a dielectric powder, and the dielectric powder particularly preferably contains barium (Ba), titanium (Ti), and oxygen (O).

[0084] A dielectric ceramic according to one embodiment is obtained by sintering a composition containing the additive for producing dielectric ceramics according to the above aspect and a dielectric powder, and the dielectric powder preferably contains at least one element selected from the group consisting of barium (Ba), strontium (Sr), calcium (Ca), zirconium (Zr), and titanium (Ti). A dielectric ceramic according to one embodiment is obtained by sintering a composition containing the additive for producing dielectric ceramics according to the above aspect and a dielectric powder, and the dielectric powder more preferably contains at least one element selected from the group consisting of barium (Ba), strontium (Sr), zirconium (Zr), and titanium (Ti). A dielectric ceramic according to one embodiment is obtained by sintering a composition containing the additive for producing dielectric ceramics according to the above aspect and a dielectric powder, and the dielectric powder more preferably contains barium (Ba) and titanium (Ti). The dielectric ceramic according to one embodiment is obtained by sintering a composition containing the additive for producing the dielectric ceramic according to the above aspect and a dielectric powder, and it is particularly preferable that the dielectric powder contains barium (Ba), titanium (Ti) and oxygen (O).

[0085] In one embodiment, the additive for producing dielectric ceramics is preferably used to produce dielectric ceramics containing at least one element selected from the group consisting of barium (Ba), strontium (Sr), calcium (Ca), zirconium (Zr) and titanium (Ti), more preferably used to produce dielectric ceramics containing at least one element selected from the group consisting of barium (Ba), strontium (Sr), zirconium (Zr) and titanium (Ti), even more preferably used to produce dielectric ceramics containing barium (Ba) and titanium (Ti), and particularly preferably used to produce dielectric ceramics containing barium (Ba), titanium (Ti) and oxygen (O).

[0086] In one embodiment, the alkaline earth metal element A contained in the composite powder containing alkaline earth metal element A and boron (B) and the alkaline earth metal element A' contained in the dielectric powder preferably contain at least one of the same element, and the dielectric powder preferably further contains at least one element selected from the group consisting of titanium (Ti) and zirconium (Zr). The alkaline earth metal element A contained in the composite powder containing alkaline earth metal element A and boron (B) and the alkaline earth metal element A' contained in the dielectric powder preferably both contain at least one element selected from the group consisting of barium (Ba) and strontium (Sr), and the dielectric powder more preferably further contains titanium (Ti). The alkaline earth metal element A contained in the composite powder containing alkaline earth metal element A and boron (B) and the alkaline earth metal element A' contained in the dielectric powder preferably both contain barium (Ba), and the dielectric powder more preferably further contains titanium (Ti). More preferably, the alkaline earth metal element A contained in the composite powder containing an alkaline earth metal element A and boron (B) and the alkaline earth metal element A' contained in the dielectric powder both contain barium (Ba), and the dielectric powder further contains titanium (Ti) and oxygen (O). In one embodiment, the alkaline earth metal element A contained in the composite powder containing an alkaline earth metal element A and boron (B) and the alkaline earth metal element A' contained in the dielectric powder contain at least one of the same elements, and both the composite powder containing an alkaline earth metal element A and boron and the dielectric powder further contain oxygen (O), and the dielectric powder further contains at least one element selected from the group consisting of titanium (Ti) and zirconium (Zr).In one embodiment, the alkaline earth metal element A contained in the composite powder containing an alkaline earth metal element A and boron (B) and the alkaline earth metal element A' contained in the dielectric powder both contain at least one element selected from the group consisting of barium (Ba) and strontium (Sr), and both the composite powder containing an alkaline earth metal element A and boron and the dielectric powder preferably further contain oxygen (O), and the dielectric powder preferably further contains at least one element selected from the group consisting of titanium (Ti) and zirconium (Zr). In one embodiment, the alkaline earth metal element A contained in the composite powder containing an alkaline earth metal element A and boron (B) and the alkaline earth metal element A' contained in the dielectric powder both contain barium (Ba), and both the composite powder containing an alkaline earth metal element A and boron and the dielectric powder preferably further contain oxygen (O), and the dielectric powder more preferably further contains titanium (Ti).

[0087] In one embodiment, the dielectric ceramic preferably contains at least one element selected from the group consisting of barium (Ba), strontium (Sr), calcium (Ca), zirconium (Zr), and titanium (Ti), more preferably contains at least one element selected from the group consisting of barium (Ba), strontium (Sr), zirconium (Zr), and titanium (Ti), even more preferably contains barium (Ba) and titanium (Ti), and particularly preferably contains barium (Ba), titanium (Ti), and oxygen (O).

[0088] Average primary particle diameter L of dielectric powder D is not particularly limited. D is preferably 0.001 μm or more, more preferably 0.005 μm or more, and even more preferably 0.01 μm or more. Within these ranges, a dielectric ceramic produced from a composition containing a dielectric powder and an additive for producing a dielectric ceramic tends to have a higher relative dielectric constant. The average primary particle diameter L of the dielectric powder Dis preferably 1 μm or less, more preferably 0.5 μm or less, and even more preferably 0.1 μm or less (lower limit: more than 0 μm). Within these ranges, a dielectric ceramic produced from a composition containing a dielectric powder and an additive for producing a dielectric ceramic may be obtained at a lower sintering temperature. Furthermore, the density of a dielectric ceramic produced from a composition containing a dielectric powder and an additive for producing a dielectric ceramic may be improved. The average primary particle diameter L of the dielectric powder D The preferred range of the average primary particle diameter L of the dielectric powder is, for example, 0.001 μm or more and 1 μm or less, 0.005 μm or more and 0.5 μm or less, 0.01 μm or more and 0.1 μm or less, etc. D The range is not limited to these.

[0089] Average primary particle diameter L of dielectric powder D can be measured and calculated by observing the dielectric powder with a scanning electron microscope (SEM). Specifically, it can be measured and calculated by the following method. SEM observation of the dielectric powder is performed, and 20 primary particles are randomly selected from the primary particles in the obtained SEM image. Next, 5 primary particles from the side with the largest primary particle diameter and 5 primary particles from the side with the smallest primary particle diameter are removed from the selected 20 primary particles, and 10 primary particles are selected. Thereafter, the average value of the primary particle diameters of the selected 10 primary particles is calculated, and the calculated average value is used as the average primary particle diameter L of the dielectric powder. D Let's say.

[0090] Average primary particle diameter L of dielectric powder D The details of the measurement method are described in the Examples.

[0091] Average primary particle size L of composite powder containing alkaline earth metal element A and boron (B) A and the average primary particle diameter L of the dielectric powder D The relationship between the average primary particle diameter L of the composite powder containing an alkaline earth metal element A and boron (B) is not particularly limited. A and the average primary particle diameter L of the dielectric powder DIn one embodiment, an additive for producing a dielectric ceramic, which is a composite powder containing an alkaline earth metal element A and boron (B), is used in an application that includes mixing with a dielectric powder, and the average primary particle diameter L of the composite powder is A and the average primary particle diameter L of the dielectric powder D The dielectric ceramic according to one embodiment is obtained by sintering a composition containing a dielectric powder and an additive for producing a dielectric ceramic, which is a composite powder containing an alkaline earth metal element A and boron (B), according to the above aspect, and the average primary particle diameter L of the composite powder is preferably 1 / 2 or 1 / 2. A and the average primary particle diameter L of the dielectric powder D The relationship preferably satisfies the following formula (I).

[0092]

number

[0093] L A / L D If L is less than 30, it may be easier to mix the additive for producing the dielectric ceramics uniformly between the particles of the dielectric powder. A / L D <20, more preferably L A / L D <10, and more preferably L A / L D <5.0. Preferably L A / L D ≧0.01, and more preferably L A / L D ≧0.05, and more preferably L A / L D ≧0.1, and particularly preferably L A / L DWithin these ranges, it may be possible to obtain an effect that a thin film is more easily formed when a slurry containing an additive for producing a dielectric ceramic and a dielectric powder is applied, and / or an effect that the dielectric powder and the additive for producing a dielectric ceramic can be mixed more uniformly. A / L D A preferred range of L is, for example, 0.01≦L A / L D <30 and range, 0.05≦L A / L D <20 and range, 0.1≦L A / L D <10 and range, 0.5≦L A / L D <5.0, etc., but L A / L D The range is not limited to these.

[0094] The additives for producing dielectric ceramics may be used alone or in combination of two or more kinds. The dielectric powders may be used alone or in combination of two or more kinds.

[0095] Although the embodiments of the present invention have been described in detail, it is clear that this is by way of illustration and example only and not of limitation, and that the scope of the present invention should be interpreted by the appended claims.

[0096] The present invention encompasses the following aspects and configurations: 1. An additive for producing dielectric ceramics, which is a composite powder containing an alkaline earth metal element A and boron, In the composite powder, the molar amount a of the alkaline earth metal element A and the molar amount b of the boron are expressed by the following formula (1):

number

number

number

number

[0097] The present invention will be described in more detail using the following examples and comparative examples, although the technical scope of the present invention is not limited to the following examples.

[0098] <Production of sintering aids for producing dielectric ceramics> [Sintering aids S1 to S3, S6 and S8 for manufacturing dielectric ceramics] Boric acid and barium hydroxide were each weighed. Ion-exchanged water was added to the weighed boric acid and barium hydroxide, respectively, to prepare raw material aqueous solution 1 containing boric acid and ion-exchanged water (raw material solution 1), and raw material aqueous solution 2 containing barium hydroxide and ion-exchanged water (raw material solution 2). The content of boric acid in raw material aqueous solution 1 was 12.4 g per 100 g of water. The content of barium hydroxide in raw material aqueous solution 2 was 18.9 g per 100 g of water.

[0099] Next, raw material aqueous solution 1 and raw material aqueous solution 2 were each heated to 65°C, and raw material aqueous solution 1 heated to 65°C and raw material aqueous solution 2 heated to 65°C were mixed in a ratio such that the value of the relational expression a / (a+b) between the molar amount a of barium and the molar amount b of boron in the produced powder (sintering aid for producing dielectric ceramics) would be the value shown in Table 1.Then, the raw material aqueous solution 1 heated to 65°C and raw material aqueous solution 2 heated to 65°C were allowed to cool to 30°C, thereby obtaining a precipitate (co-precipitate).

[0100] The resulting precipitate was then filtered using a small funnel and filter paper to separate the solid and liquid, and the resulting cake-like precipitate was dried in a small dryer at 80°C for 12 hours. The dried powder was then crushed in a mortar.

[0101] The crushed powder was then fired in a small firing furnace at 400°C for 3 hours to obtain a powder. 30 g of the obtained powder was then placed in a 250 mL polypropylene container, and φ2 mm zirconia balls were added in an amount equivalent to 33% by volume of the volume of the polypropylene container. The powder was then crushed in a dry ball mill for 20 hours to obtain a crushed powder. The crushed powder obtained was used as a sintering aid for producing dielectric ceramics.

[0102] In this manner, sintering aids S1 to S3, S6 and S8 for producing dielectric ceramics were produced, respectively.

[0103] [Sintering aid S4 for manufacturing dielectric ceramics] BaCO3 and H3BO3 were weighed as starting materials in a molar ratio of BaCO3:H3BO3 = 1:2. The weighed BaCO3 and H3BO3 were mixed with ethanol as a dispersant and polyethylene balls in a wet ball mill for 5 hours. The resulting mixture was dried in an air bath at 120°C for 16 hours to obtain a mixed powder. The resulting mixed powder was calcined in air at 800°C for 48 hours to obtain BaB2O4 powder. 30 g of the resulting BaB2O4 powder was then placed in a 250 mL polypropylene container, filled with 2 mm diameter zirconia balls in an amount equivalent to 33% by volume of the container's volume, and crushed in a dry ball mill for 20 hours to obtain crushed BaB2O4 powder. The crushed BaB2O4 powder was used as sintering aid S4 for dielectric ceramics production.

[0104] [Sintering aid S5 for manufacturing dielectric ceramics] The raw material boric acid was heated to obtain molten boron oxide. The obtained molten boron oxide was converted into a sheet-like glass state using the water-cooled W rolls of a cooling, solidification, and crushing device and cooled in an air-cooled vertical duct. The sheet-like glass-like boron oxide was then crushed using a Oniha double-roll crusher, and the obtained boron oxide powder was directly placed in a metal container with a lid, obtaining boron oxide powder while being protected from contact with the outside air. 30 g of the obtained boron oxide powder was then placed in a 250 mL polypropylene container, and 2 mm diameter zirconia balls were added in an amount equivalent to 33% by volume of the polypropylene container's volume. The container was then crushed in a dry ball mill for 20 hours. The resulting crushed boron oxide powder was designated as sintering aid S5 for the production of dielectric ceramics.

[0105] [Sintering aid S7 for manufacturing dielectric ceramics] Sintering aid S7 for producing dielectric ceramics was produced in the same manner as sintering aid S1 for producing dielectric ceramics, except that in producing raw material aqueous solution 2, the type of compound containing alkaline earth metal element A was changed from barium hydroxide to strontium hydroxide octahydrate, the content of strontium hydroxide octahydrate in raw material aqueous solution 2 was 10.6 g per 100 g of water, and raw material aqueous solutions 1 and 2 were mixed in a ratio such that the value of the relational expression a / (a+b) between the molar amount a of strontium and the molar amount b of boron in the produced powder (sintering aid for producing dielectric ceramics) was the value shown in Table 1.

[0106] [Sintering aids S9-S11 for manufacturing dielectric ceramics] Sintering aid S9 for producing dielectric ceramics was prepared in the same manner as sintering aid S2 for producing dielectric ceramics, except that the firing conditions were changed from a firing temperature of 400°C and a firing time of 3 hours to a firing temperature of 600°C and a firing time of 3 hours.

[0107] In addition, sintering aid S10 for producing dielectric ceramics was prepared in the same manner as sintering aid S2 for producing dielectric ceramics, except that the firing conditions were changed from a firing temperature of 400°C and a firing time of 3 hours to a firing temperature of 500°C and a firing time of 3 hours.

[0108] In addition, sintering aid S11 for producing dielectric ceramics was prepared in the same manner as sintering aid S2 for producing dielectric ceramics, except that the firing conditions were changed from a firing temperature of 400°C and a firing time of 3 hours to a firing temperature of 450°C and a firing time of 3 hours.

[0109] The sintering aids S1 to S11 for producing dielectric ceramics produced above were all powders.

[0110] The characteristics of the sintering aids S1 to S11 for producing dielectric ceramics are shown in Tables 1 and 2.

[0111] <Evaluation of sintering aids for manufacturing dielectric ceramics> [Average primary particle size L A ] The sintering aid for producing dielectric ceramics produced above was observed using a scanning electron microscope (SEM) manufactured by JEOL Ltd., a field emission scanning electron microscope JSM-7900F. The SEM observation conditions were an acceleration voltage of 0.80 kV, a probe current of #3, a working distance of 2-3 mm, a detector UED filter No. 0, a measurement mode GBSH-S, and magnifications ranging from 10,000x to several hundred thousandx. SEM images were obtained. Next, 20 primary particles were randomly selected from the primary particles in the obtained SEM image. Next, 5 primary particles with larger primary particle diameters and 5 primary particles with smaller primary particle diameters were removed from the selected 20 primary particles, leaving 10 primary particles. The average primary particle diameter of the selected 10 primary particles was then calculated, and this average was used as the average primary particle diameter L of the sintering aid for producing dielectric ceramics. A These values are shown in Tables 1 and 2.

[0112] The above average primary particle diameter L A The sintering aids for producing dielectric ceramics manufactured above were subjected to SEM observation using the same equipment as used in the evaluation of (1). Figure 3 shows an SEM image of sintering aid S1 for producing dielectric ceramics. Figure 4 shows an SEM image of sintering aid S2 for producing dielectric ceramics. Figure 5 shows an SEM image of sintering aid S5 for producing dielectric ceramics (boron oxide powder).

[0113] [Composition analysis] (ICP atomic emission spectrometry (inductively coupled plasma atomic emission spectrometry)) The sintering aid for producing dielectric ceramics manufactured above was used as a sample, and the sample was dissolved in acid, diluted, and adjusted to the optimum concentration. The aqueous solution sample was atomized and introduced into an inductively coupled plasma (ICP) as an ionization source, and the elements ionized in the plasma were separated and detected using a quadrupole mass spectrometer. In this way, elemental analysis of the sintering aid for producing dielectric ceramics manufactured above was performed.

[0114] As a result, it was confirmed that the sintering aids S1 to S4, S6, and S8 to S11 for producing dielectric ceramics contain barium (Ba) and boron (B) as the alkaline earth metal element A, respectively.

[0115] It was also confirmed that the sintering aid S7 for producing dielectric ceramics contains strontium (Sr) as the alkaline earth metal element A and also contains boron (B).

[0116] It was also confirmed that the sintering aid S5 for producing dielectric ceramics does not contain the alkaline earth metal element A, but contains boron (B).

[0117] In this evaluation, the molar amount a of the alkaline earth metal element A and the molar amount b of boron (B) in the sintering aids S1 to S11 for producing dielectric ceramics were further calculated. The values of the relational expression a / (a+b) for the molar amount a of the alkaline earth metal element A and the molar amount b of boron (B) in the sintering aids S1 to S11 for producing dielectric ceramics are shown in Tables 1 and 2, respectively.

[0118] (Scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS) point analysis) Point analysis of the elements in the sintering additive for the dielectric ceramics fabricated above was performed using an energy dispersive X-ray analyzer (EDS) attached to a scanning electron microscope (SEM). For this measurement, a field-emission scanning electron microscope (JSM-7900F) was used as the SEM, and an Oxford Instruments AZtec Energy (Model X-MaxN20) was used as the EDS. The measurement conditions were an accelerating voltage of 10 kV, a probe current of #10, a working distance of 15 mm, an LED filter for the detector, SEM measurement mode, and a magnification of 10,000x. One hundred particles were selected, and point analysis of each selected particle was performed using SEM-EDS for the elements Ba or Sr, as well as B and O. One measurement point was performed per particle.

[0119] In this evaluation, when both alkaline earth metal element A and boron (B) were confirmed in the analysis results of 90 or more particles out of 100 particles selected from the powder to be measured, the powder to be measured was determined to be a composite powder containing alkaline earth metal element A and boron (B).

[0120] Analysis of 100 selected particles of sintering aids S1 to S4 and S8 to S11 for the production of dielectric ceramics confirmed the presence of barium (Ba), boron (B), and oxygen (O). From these results, it was determined that sintering aids S1 to S4, S6, and S8 to S11 for the production of dielectric ceramics are composite powders containing alkaline earth metal element A and boron (B), respectively.

[0121] In sintering aid S6 for producing dielectric ceramics, the number of particles in which both alkaline earth metal element A and boron (B) were confirmed was less than 90 out of 100 particles selected from the powder to be measured. From this result, it was determined that sintering aid S6 for producing dielectric ceramics is not a composite powder containing alkaline earth metal element A and boron (B).

[0122] In the sintering aid S7 for the production of dielectric ceramics, the analysis results for each of the selected 100 particles confirmed the presence of strontium (Sr), boron (B), and oxygen (O). From these results, it was determined that the sintering aid S7 for the production of dielectric ceramics is a composite powder containing alkaline earth metal element A and boron (B).

[0123] In the sintering aid S5 for producing dielectric ceramics, the analysis results for each of the selected 100 particles showed that the alkaline earth metal element A was not confirmed, but boron (B) and oxygen (O) were confirmed.

[0124] The results are shown in Tables 1 and 2.

[0125] (Analysis by X-ray diffraction (XRD) method) The sintering aids S1 to S4 and S6 to S11 for producing dielectric ceramics produced above were measured using a desktop X-ray diffractometer, MiniFlex (registered trademark), manufactured by Rigaku Corporation. Specifically, a powder sample was packed into a sample holder, and the sample holder with the powder sample packed therein was placed in a sample changer inside the X-ray diffractometer. The X-ray diffraction patterns were measured using CuKα as the X-ray source under the following conditions: tube current 15 mA, tube voltage 40 kV, 2θ = 20.0° to 70.0°, step width: 0.02°, and measurement speed: 0.03° / sec.

[0126] The results of the X-ray diffraction measurement were subjected to Rietveld analysis using the integrated powder X-ray analysis software PDXL (manufactured by Rigaku Corporation) attached to an X-ray diffractometer (MiniFlex (registered trademark) 600 desktop X-ray diffractometer manufactured by Rigaku Corporation).

[0127] When two or more crystalline phases of compounds containing barium (Ba), boron (B), and oxygen (O) (Ba-BO compounds) were confirmed, accounting for 5% by mass or more of the total amount (100% by mass) of the crystalline phases shown as candidates in the analysis software, the powder containing barium (Ba), boron (B), and oxygen (O) was determined to contain two or more types of crystalline phases. The crystalline phases of Ba-BO compounds were confirmed from the charts of various "crystals of Ba-BO compounds" in the ICSD (Inorganic Crystal Structure Database).

[0128] When two or more crystalline phases of compounds containing strontium (Sr), boron (B), and oxygen (O) (Sr-BO compounds) were confirmed, accounting for 5% or more by mass of the total amount (100% by mass) of the crystalline phases shown as candidates in the analysis software, the powder containing strontium (Sr), boron (B), and oxygen (O) was determined to contain two or more types of crystalline phases. The crystalline phases of Sr-BO compounds were confirmed from the various "Crystals of Sr-BO Compounds" charts in the ICSD (Inorganic Crystal Structure Database).

[0129] When a halo pattern is observed in the chart obtained by X-ray diffraction measurement, the powder used as a sintering aid for manufacturing dielectric ceramics is judged to contain an amorphous phase. In this evaluation, a halo pattern is a broad peak with a peak width of 5° or more in 2θ in the chart obtained by X-ray diffraction measurement.

[0130] As a result of analysis by X-ray diffraction (XRD), two or more types of crystalline phases were confirmed in the measurements of sintering aids S1, S6 and S8 for manufacturing dielectric ceramics.

[0131] In the measurements of sintering aids S2, S3, and S9–S11 for dielectric ceramics, background lines were drawn on the charts obtained by X-ray diffraction measurement, and positions around 2θ of 27° (within the range of 27° ± 4°) and 43° (within the range of 43° ± 4°) were confirmed. Broad peaks with a peak width of 5° or more in 2θ were confirmed at positions around 27° (within the range of 27° ± 4°) and 43° (within the range of 43° ± 4°). In the measurements of sintering aids S2, S3, and S9–S11 for dielectric ceramics, Rietveld analysis did not confirm the presence of a Ba-BO compound crystalline phase, which accounted for 5% or more by mass of the total amount (100% by mass) of crystalline phases indicated as candidates in the analysis software. Furthermore, in the measurements of sintering aids S2, S3, and S9–S11 for dielectric ceramics, no clear peaks other than the halo pattern were confirmed.

[0132] In the measurement of sintering aid S7 for the production of dielectric ceramics, background lines were drawn on the chart obtained by X-ray diffraction measurement, and positions around 2θ of 29° (within the range of 29° ± 8°) and 46° (within the range of 46° ± 6°) were confirmed. Broad peaks with a peak width of 5° or more in 2θ were confirmed at positions around 29° (within the range of 29° ± 8°) and 46° (within the range of 46° ± 6°). In the measurement of sintering aid S7 for the production of dielectric ceramics, Rietveld analysis did not confirm the presence of a Sr-BO compound crystalline phase, which accounted for 5% or more by mass of the total amount (100% by mass) of crystalline phases indicated as candidates in the analysis software. Furthermore, in the measurement of sintering aid S7 for the production of dielectric ceramics, no clear peaks other than the halo pattern were confirmed.

[0133] In the measurement of sintering aid S4 for the production of dielectric ceramics, no clear halo pattern was observed, and a clear peak was confirmed at a position overlapping with the peak position of BaB2O4 crystals. In addition, in the measurement of sintering aid S4 for the production of dielectric ceramics, Rietveld analysis confirmed only one crystalline phase of a Ba-BO compound, which accounted for more than 5 mass% of the total amount (100 mass%) of the crystalline phases shown as candidates in the analysis software. Analysis by X-ray diffraction (XRD) determined that the phase state of sintering aid S4 for the production of dielectric ceramics is a single crystalline phase.

[0134] In the sintering aids S1 to S3 and S8 to S11 for producing dielectric ceramics, no peaks corresponding to the raw materials barium hydroxide and boric acid were confirmed in the X-ray diffraction patterns.

[0135] In the sintering aid S6 for producing dielectric ceramics, the peak of the raw material barium hydroxide was confirmed in the X-ray diffraction pattern.

[0136] Furthermore, in the sintering aid S7 for producing dielectric ceramics, no peaks corresponding to the raw material strontium hydroxide octahydrate or boric acid were confirmed in the X-ray diffraction pattern.

[0137] The results are shown in Tables 1 and 2.

[0138] FIG. 1 shows charts obtained by X-ray diffraction of the sintering aids S1 to S3 for producing dielectric ceramics, the raw material boric acid, and the raw material barium hydroxide.

[0139] Sintering aids S1 to S3 for manufacturing dielectric ceramics, Ba3(B3O6)2 crystal, BaBO 13 Crystal and Ba3B6O 11 Figure 2 shows the chart obtained by X-ray diffraction of (OH)2 crystals.

[0140] [Hygroscopicity] The sintering aid for producing dielectric ceramics produced above was measured using the TG-DTA (simultaneous differential thermal analysis) method. Measurements were performed using a TG-DTA 2020SA manufactured by NETZSH. 30 mg of the powder used as the sintering aid for producing dielectric ceramics was placed in a platinum pan, heated to 100°C, and then allowed to cool naturally to room temperature. The mass at the start of cooling and the mass after 6 hours were measured. The mass increase rate after 6 hours was then evaluated according to the following formula. The smaller the mass increase rate after 6 hours, the better the moisture absorption. The evaluation results are shown in Tables 1 and 2.

[0141]

number

[0142] <Evaluation Criteria> A: The mass increase rate after 6 hours is less than 1.0%. B: The mass increase rate after 6 hours is 1.0% or more and less than 3.0%; C: The mass increase rate after 6 hours is 3.0% or more.

[0143] <Manufacturing of dielectric ceramics> In producing the dielectric ceramics, barium titanate (BaTiO3) powder (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., standard content: 99.0+% (Subtraction Method)) was used as the dielectric powder.

[0144] (Average primary particle size L D ) SEM observation of the dielectric powder was performed using a JEOL Ltd. field emission scanning electron microscope JSM-7900F. The SEM observation measurement conditions were an acceleration voltage of 0.80 kV, a probe current of #3, a working distance of 2-3 mm, a detector UED filter No. 0, a measurement mode GBSH-S, and magnifications ranging from 10,000x to several hundred thousandx, to obtain an SEM image. Next, 20 primary particles were randomly selected from the primary particles in the obtained SEM image. Next, 5 primary particles with larger primary particle diameters and 5 primary particles with smaller primary particle diameters were removed from the selected 20 primary particles, leaving 10 primary particles. The average primary particle diameter of the selected 10 primary particles was then calculated, and this calculated average value was used to determine the average primary particle diameter L of the dielectric powder. D It was decided.

[0145] As a result of this evaluation, the average primary particle diameter L D was confirmed to be 0.06 μm.

[0146] In addition, the average primary particle diameter L of the powder used as a sintering aid for producing dielectric ceramics A and the average primary particle diameter L of the dielectric powder D The relationship between these is shown in Tables 3 and 4.

[0147] [Dielectric Ceramics 1-11] The above-mentioned barium titanate powder, which is a dielectric powder, and the sintering aid for producing dielectric ceramics produced above were mixed in a wet ball mill under the following conditions. When determining the amount of barium titanate and the amount of sintering aid for producing dielectric ceramics to be used, the purity of the barium titanate was set to 99.0 mass%. The purity of the barium titanate was calculated using a NETZSH TG-DTA 2020SA from the mass loss rate when barium titanate (BaTiO3) powder (Fujifilm Wako Pure Chemical Industries, Ltd., standard content: 99.0+% (Subtraction Method)) was heated from 25°C to 1000°C in an air atmosphere.

[0148] <Conditions for mixing using a wet ball mill> Mixing target Barium titanate powder: 10.0g Sintering aid for producing dielectric ceramics: 2 mol per 100 mol of barium titanate Solvent: Ethanol Slurry solids concentration: 6.3% by mass Ball: φ2mm YTZ ball (Nikkato Corporation, zirconia ball, product name: YTZ series, φ2mm) Container: 250 mL bottle (As One Corporation, polypropylene, product name: Good Boy, 250 mL, transparent container) Ball volume: 1 / 2% by volume of the bottle (manufactured by AS ONE Corporation, made of polypropylene, product name: Good Boy, 250 mL, transparent container) Ball milling time: 5 hours.

[0149] The resulting mixture was separated into a slurry and balls using a sieve, and the slurry was then dried in a rotary evaporator to obtain a mixed powder.

[0150] Next, an 8% by weight aqueous solution of polyvinyl alcohol (PVA) was added to the resulting mixed powder so that the amount of the 8% by weight aqueous solution was 1% by weight based on the total weight of the mixed powder and the 8% by weight aqueous solution of polyvinyl alcohol (PVA). The mixture was then mixed in a mortar until thoroughly mixed to obtain a pellet-molded sample. Using a benchtop hydraulic press, an SE Work Press (manufactured by Mitsusei Hydraulic Machinery Co., Ltd.) and a φ15 (15 mm diameter) carbide die, 1.5 g of the pellet-molded sample was uniaxially pressed at 0.20 MPa to form a cylindrical (coin-shaped) shape. The molded pellet-molded sample was then placed in a polyethylene (PE) sample bag and left for 30 minutes. The molded pellet-molded sample was then crushed into powder using a Teflon rod in the sample bag, passed through a 500 μm mesh sieve, and placed in a polyethylene (PE) sample bag. Then, 1.5 g of powdered pellet molding sample was taken out of the sample bag (made of polyethylene (PE)), and using a benchtop hydraulic press SE Work Press manufactured by Mitsusei Hydraulic Machinery Co., Ltd. and a carbide die φ15 (diameter 15 mm), the 1.5 g of powdered pellet molding sample taken out of the sample bag was uniaxially pressed at 0.20 MPa to mold it into pellets.

[0151] The obtained pellets were fired under the following conditions using the following apparatus to obtain a sintered body of dielectric ceramics.

[0152] <Firing equipment and firing conditions> Firing furnace: A small, high-speed heating electric furnace (product name: Superburn, manufactured by Motoyama Co., Ltd.) Container: Alumina sagger Firing conditions: Firing temperature 1000°C, heating time 200 minutes, holding time 2 hours, cooling time 200 minutes.

[0153] In this manner, dielectric ceramics 1 to 11 were produced, respectively.

[0154] [Dielectric Ceramics 12] Dielectric ceramic 12 was produced in the same manner as in the production of dielectric ceramic 1, except that no sintering aid for producing dielectric ceramics was added.

[0155] <Evaluation of dielectric ceramics> [density] The mass of the dielectric ceramics (pellets after firing) produced above was measured, and the diameter and thickness were measured using a micrometer MDC-25M manufactured by Mitutoyo Corporation, and the density was calculated from these results.The theoretical density of barium titanate for the dielectric ceramics (pellets after firing) produced above was 6.02 g / cm. 3 The relative density (unit: %) was calculated based on the theoretical density of barium titanate. The results are shown in Tables 3 and 4. In these tables, the relative density (unit: %) to BaTiO3 represents the relative density (unit: %) of the dielectric ceramics based on the theoretical density of barium titanate.

[0156] From the results in Tables 1 to 4, it was confirmed that the sintering aids S1 to S3 and S7 to S11 for producing dielectric ceramics, which are additives for producing dielectric ceramics according to the examples, can achieve high density of dielectric ceramics, and that these additives for producing dielectric ceramics can easily achieve a finely divided powder state and have low moisture absorption.

[0157] On the other hand, it was confirmed that the sintering aids S4 and S5 for producing dielectric ceramics, which are the additives for producing dielectric ceramics according to the comparative examples, are less likely to produce finely divided powders than the additives for producing dielectric ceramics according to the examples. From this result, it is inferred that the sintering aids S4 and S5 for producing dielectric ceramics, which are the additives for producing dielectric ceramics according to the comparative examples, will result in lower productivity if finer particles are used, and that it will be more difficult to reduce the size and / or thickness of components obtained using the dielectric ceramics if finer particles are not used.

[0158] It was also confirmed that the sintering aids S5 and S6 for producing dielectric ceramics, which are the additives for producing dielectric ceramics according to the comparative examples, are more hygroscopic than the additives for producing dielectric ceramics according to the examples. From this result, it is considered that when the sintering aids S5 and S6 for producing dielectric ceramics, which are the additives for producing dielectric ceramics according to the comparative examples, are used, the quality of the dielectric ceramics is more likely to vary.

[0159] It was also confirmed that the dielectric ceramic 12 manufactured without using the additive for manufacturing dielectric ceramics according to the example and without using the additive for manufacturing dielectric ceramics according to the comparative example had a lower density than the dielectric ceramic manufactured using the additive for manufacturing dielectric ceramics according to the example.

[0160] [Table 1]

[0161] [Table 2]

[0162] [Table 3]

[0163] [Table 4]

Claims

1. An additive for producing dielectric ceramics, which is a composite powder containing an alkaline earth metal element A and boron, In the composite powder, the molar amount a of the alkaline earth metal element A and the molar amount b of the boron are expressed by the following formula (1): [Equation 1] Fulfilling The composite powder satisfies at least one condition selected from the group consisting of the following condition (i) and the following condition (ii): Condition (i) The composite powder contains an amorphous phase; Condition (ii) The composite powder contains two or more types of crystal phases; Additive for manufacturing dielectric ceramics.

2. 2. The additive for producing dielectric ceramics according to claim 1, wherein the alkaline earth metal element A includes barium.

3. In the composite powder, the molar amount a of the alkaline earth metal element A and the molar amount b of the boron are expressed by the following formula (2): [Equation 2] The additive for producing dielectric ceramics according to claim 1, which satisfies the above.

4. The average primary particle diameter L of the composite powder Ａ The additive for producing dielectric ceramics according to claim 1, wherein the average particle size is 2.0 μm or less.

5. Used in applications involving mixing with dielectric powders, The dielectric powder contains an alkaline earth metal element A′, The alkaline earth metal element A and the alkaline earth metal element A' contain at least one of the same element. The additive for producing dielectric ceramics according to claim 1.

6. Used in applications involving mixing with dielectric powders, 2. The additive for producing dielectric ceramics according to claim 1, wherein the dielectric powder contains barium and titanium.

7. Used in applications involving mixing with dielectric powders, The average primary particle diameter L of the composite powder Ａ and the average primary particle diameter L of the dielectric powder. Ｄ is represented by the following formula (I): [Equation 3] The additive for producing dielectric ceramics according to claim 1, which satisfies the above.

8. A dielectric ceramic obtained by sintering a composition containing the additive for producing a dielectric ceramic according to any one of claims 1 to 7 and a dielectric powder.

9. The dielectric powder contains an alkaline earth metal element A′, The alkaline earth metal element A and the alkaline earth metal element A' contain at least one of the same element. The dielectric ceramic according to claim 8.

10. The dielectric ceramic according to claim 8 , wherein the dielectric powder contains barium and titanium.

11. The average primary particle diameter L of the composite powder Ａ and the average primary particle diameter L of the dielectric powder. Ｄ is represented by the following formula (I): [Equation 4] The dielectric ceramic according to claim 8, which satisfies the following:

Images