JP2016150872A - Barium titanate and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide barium titanate which is usable as a functional ceramic in spite of containing niobium and sulfur, and in particular usable as a functional ceramic excellent in dielectric property in spite of containing niobium and sulfur.SOLUTION: The barium titanate is provided which contains a sulfur atom, a niobium atom and a metal atom M ( M is one or two or more element selected from aluminum, iron, gallium, yttrium, indium, antimony, bismuth, lanthanum, neodymium and samarium) and in which the content of the sulfur atom is 500 mass.ppm or less, the content of niobium atom is 1 to 1000 mass.ppm and a ratio of the total molar number of the metal M to the molar number of the niobium atom (M/Nb) is 1 to 3.SELECTED DRAWING: None

Description

  The present invention relates to barium titanate used as a raw material for functional ceramics such as piezoelectric bodies, multilayer ceramic capacitors, optoelectronic materials, dielectrics, semiconductors, and sensors, and a method for producing the same.

  Barium titanate has been conventionally used as a raw material for functional ceramics such as piezoelectric bodies and multilayer ceramic capacitors. In recent years, multilayer ceramic capacitors are required to have an increased number of layers and a higher dielectric constant in order to increase the capacity. Therefore, the raw material barium titanate is required to have a fine and high tetragonal property.

  For this reason, barium titanate used as a raw material for functional ceramics has been designed to increase the crystallinity by reducing the impurity content as much as possible in order to provide fine and high tetragonal properties. (For example, Patent Documents 1 to 3).

  Here, as one method for producing barium titanate, a so-called solid phase method is known in which barium carbonate and titanium dioxide are mixed and the resulting mixture is fired. As a method for producing titanium dioxide used in this solid phase method, after cooling gaseous titanium tetrachloride into a liquid state, it is reacted with oxygen at a high temperature to obtain chlorine dioxide by separating chlorine ( The chlorine method) and the method of obtaining titanium dioxide by washing titanium oxyhydroxide obtained by hydrolyzing titanium oxysulfate, drying and baking (sulfuric acid method) are mainly known.

  As described above, since barium titanate used as a raw material for functional ceramics is required to reduce the impurity content as much as possible, it is a raw material for producing barium titanate. Titanium dioxide obtained by the chlorine method is generally used as titanium because the impure component chlorine becomes a gas and is easily separated and can be highly purified (for example, Patent Document 4).

JP-A-8-165200 JP 2006-27971 A International Publication No. 2003/004416 Pamphlet JP 2006-265094 A

  On the other hand, titanium dioxide obtained by the sulfuric acid method has a conventional functionality because niobium contained in the raw ilmenite ore and sulfur derived from sulfuric acid used in the manufacturing process inevitably remain. It was considered inappropriate as a raw material for producing barium titanate for ceramics.

  However, the sulfuric acid method has advantages such as obtaining titanium dioxide having a small particle size and low production cost compared to the chlorine method. Therefore, it is desired to develop barium titanate for functional ceramics obtained by using titanium dioxide containing niobium and sulfur as impurities, such as titanium dioxide obtained by the sulfuric acid method.

  Therefore, the object of the present invention is to provide barium titanate that can be used for functional ceramics such as multilayer ceramic capacitors and piezoelectric bodies, while containing niobium and sulfur, in particular, while containing niobium and sulfur, and having dielectric properties. An object of the present invention is to provide a barium titanate that can be used as a functional ceramic application having excellent performance, and a production method thereof.

The above-mentioned problems of the present invention are solved by the following present invention. That is, the present invention (1) is a sulfur atom, a niobium atom, and a metal atom M (M is one or two selected from aluminum, iron, gallium, yttrium, indium, antimony, bismuth, lanthanum, neodymium, and samarium. Is an element of a species or more), and
The sulfur atom content is 500 mass ppm or less, the niobium atom content is 1-1000 mass ppm,
The ratio of the total number of moles of metal atoms M to the number of moles of niobium atoms (M / Nb) is 1 to 3,
The barium titanate characterized by this is provided.

Further, the present invention (2) relates to a compound having titanium dioxide, barium carbonate, and a trivalent metal ion M ³⁺ (M is aluminum, iron, gallium, yttrium, indium, antimony, bismuth, lanthanum, neodymium, and samarium. A first step of obtaining a raw material mixture by mixing one or two or more elements selected from
Baking the raw material mixture to obtain barium titanate;
Having
The manufacturing method of the barium titanate characterized by these is provided.

  According to the present invention, barium titanate that can be used for functional ceramics such as multilayer ceramic capacitors and piezoelectric bodies while containing niobium and sulfur, in particular, it has excellent dielectric properties while containing niobium and sulfur. Barium titanate and a method for producing the same can be provided.

The barium titanate of the present invention is a sulfur atom, a niobium atom, and a metal atom M (M is one or two selected from aluminum, iron, gallium, yttrium, indium, antimony, bismuth, lanthanum, neodymium, and samarium. The above elements), and
The sulfur atom content is 500 mass ppm or less, the niobium atom content is 1-1000 mass ppm,
The ratio of the total number of moles of metal atoms M to the number of moles of niobium atoms (M / Nb) is 1 to 3,
It is a barium titanate characterized by these.

  The barium titanate of the present invention contains a sulfur atom, a niobium atom, and a metal atom M.

  Content of the sulfur atom in the barium titanate of this invention is 500 mass ppm or less, Preferably it is 10-400 mass ppm, Most preferably, it is 20-350 ppm. If the sulfur atom content in the barium titanate exceeds the above range, tetragonal barium titanate becomes difficult to be obtained, and the dielectric properties are lowered. In addition, content of the sulfur atom in the barium titanate of this invention is content of atom conversion, and is a mass ratio of the sulfur atom of atom conversion with respect to the total mass of the barium titanate of this invention.

  The content of niobium atoms in the barium titanate of the present invention is 1-1000 ppm by mass, preferably 10-800 ppm by mass, particularly preferably 20-700 ppm. When the content of niobium atoms in the barium titanate exceeds the above range, the barium titanate is made into a semiconductor and the dielectric properties are lowered. In addition, content of the niobium atom in the barium titanate of this invention is content of atom conversion, and is a mass ratio of the niobium atom of atom conversion with respect to the total mass of the barium titanate of this invention.

  The barium titanate of the present invention is any one of metal atom M, that is, aluminum atom, iron atom, gallium atom, yttrium atom, indium atom, antimony atom, bismuth atom, lanthanum atom, neodymium atom and samarium atom. Or contain two or more of these atoms. The metal atom M related to the barium titanate of the present invention is an aluminum atom or an iron atom. Even if titanium dioxide obtained by the sulfuric acid method is used as a raw material, the dielectric properties of barium titanate due to the inclusion of niobium atoms and sulfur atoms It is preferable at the point from which the effect of reducing the fall of becomes high.

  The total content of metal atoms M in the barium titanate of the present invention is such that the ratio of the total number of moles of metal atoms M to the number of moles of niobium atoms (M / Nb) is 1 to 3, preferably 1 to 2.75. In the range which becomes, it is suitably selected, Preferably it is 1-1200 mass ppm, Most preferably, it is 10-1000 mass ppm. In addition, the sum total of content of the metal atom M in the barium titanate of this invention is the sum of content of atom conversion, and the total mass of the metal atom M of atom conversion with respect to the total mass of the barium titanate of this invention. It is a ratio.

  In the barium titanate of the present invention, the ratio (M / Nb) of the total number of moles of metal atoms M to the number of moles of niobium atoms is 1 to 3, preferably 1 to 2.75. When the ratio of the total number of moles of metal atoms M to the number of moles of niobium atoms (M / Nb) is in the above range, the semiconductorization of barium titanate is suppressed and the effect of reducing the deterioration of the dielectric properties of barium titanate is reduced. Is preferable from the viewpoint of increasing. The number of moles of niobium atoms in the barium titanate of the present invention is the number of moles of niobium converted into atoms in the barium titanate of the present invention, and the metal atoms in the barium titanate of the present invention. The total number of moles of M is the total number of moles in terms of atoms of M present in the barium titanate of the present invention.

  In the barium titanate of the present invention, the ratio (M / S) of the total number of moles of metal atoms M to the number of moles of sulfur atoms is preferably 1 to 10, particularly preferably 2 to 9. Since the ratio (M / S) of the total number of moles of metal atoms M to the number of moles of sulfur atoms is in the above range, grain growth is suppressed, and therefore, fine barium titanate tends to be formed. In addition, the number of moles of sulfur atoms in the barium titanate of the present invention is the number of moles of sulfur present in the barium titanate of the present invention in terms of atoms.

  The barium titanate of the present invention may contain atoms such as Na, Mg, Ca, Zr, Si, P, Sr, and Mn as long as the effects of the present invention are not impaired.

  The average particle diameter of the barium titanate of the present invention is preferably 0.01 to 0.8 μm, particularly preferably 0.05 to 0.5 μm. When the average particle diameter of barium titanate is in the above range, barium titanate having excellent dielectric properties such as high capacity and high dielectric constant is obtained.

  In addition, in this invention, the average particle diameter of barium titanate is the particle diameter of a primary particle, a diameter is measured about 1000 primary particles arbitrarily extracted with the scanning electron microscope (SEM) photograph, and those averages are measured. The value was defined as the average particle size.

The BET specific surface area of the barium titanate of the present invention is preferably 1 to 30 m ² / g, particularly preferably 1.5 to ²⁰ m ² / g.

  The barium titanate of the present invention has a sulfur atom content of 500 ppm by mass or less, preferably 10 to 400 ppm by mass, a niobium atom content of 1 to 1000 ppm by mass, preferably 10 to 800 ppm, and The ratio of the total number of moles of metal atoms M to the number of moles of niobium atoms (M / Nb) is 1 to 3, preferably 1 to 2.75, so that sulfur atoms and niobium atoms are contained. Regardless, the dielectric properties are comparable or close to that of barium titanate without sulfur and niobium atoms. Therefore, the barium titanate of the present invention is suitable as a raw material for functional ceramics used for multilayer ceramic capacitors, piezoelectric bodies, optoelectronic materials, dielectrics, semiconductors, temperature sensors and the like.

The method for producing barium titanate of the present invention comprises a compound having titanium dioxide, barium carbonate, and a trivalent metal ion M ³⁺ (M is aluminum, iron, gallium, yttrium, indium, antimony, bismuth, lanthanum, neodymium). And one or more elements selected from samarium), and a first step of obtaining a raw material mixture,
Baking the raw material mixture to obtain barium titanate;
Having
Is a method for producing barium titanate.

The method for producing barium titanate according to the present invention comprises a first step in which titanium dioxide, barium carbonate, and a compound having a trivalent metal ion M ³⁺ are mixed to obtain a raw material mixture, and a first step. And firing the obtained raw material mixture to obtain barium titanate.

The first step is a step of obtaining a raw material mixture by mixing titanium dioxide, barium carbonate, and a compound having a trivalent metal ion M ³⁺ .

  The titanium dioxide according to the first step is powdered titanium dioxide. The average particle diameter of the titanium dioxide according to the first step is preferably 0.1 to 1.0 μm, particularly preferably 0.2 to 0.8 μm. It is preferable that the average particle diameter of titanium dioxide is in the above range in that fine barium titanate can be obtained.

  The barium carbonate according to the first step is powdered barium carbonate. The average particle diameter of the barium carbonate according to the first step is preferably 0.1 to 1.0 μm, particularly preferably 0.2 to 0.7 μm. When the average particle diameter of barium carbonate is in the above range, it is preferable in that fine barium titanate can be obtained.

The compound having a trivalent metal ion M ^{3+ according} to the first step is a compound in which M in a trivalent ion state exists in the compound. M relating to the compound having a trivalent metal ion M ³⁺ is one or more elements selected from aluminum, iron, gallium, yttrium, indium, antimony, bismuth, lanthanum, neodymium and samarium, preferably Aluminum and iron. Examples of the compound having a trivalent metal ion M ^{3+ according} to the first step include a trivalent M oxide, a trivalent M salt, a plurality of trivalent M complex salts, and a trivalent M compound. A complex. More specifically, the compound having the trivalent metal ion M ^{3+ according} to the first step is a trivalent M oxide such as aluminum oxide (Al ₂ O ₃ ) or iron oxide (Fe ₂ O ₃ ). Trivalent M carbonates such as aluminum carbonate (Al ₂ (CO ₃ ) ₃ ) and iron carbonate (Fe ₂ (CO ₃ ) ₃ ); three such as aluminum chloride (AlCl ₃ ) and iron chloride (FeCl ₃ ) Trivalent M nitrate such as aluminum nitrate (Al (NO ₃ ) ₃ ), iron nitrate (Fe (NO ₃ ) ₃ ); aluminum sulfate (Al ₂ (SO ₄ ) ₃ ), sulfuric acid Trivalent M sulfate such as iron (Fe ₂ (SO ₄ ) ₃ ); trivalent phosphate such as aluminum phosphate (AlPO ₄ ) and iron phosphate (FePO ₄ ), aluminum formate (Al (HCOO) ₃ ) Aluminum lactate (Al (C ₂ H ₄ (OH) COO) ₃ ), iron formate (Fe (HCOO) ₃ ), iron lactate (Fe (C ₂ H ₄ (OH) COO) ₃ ), and the like. The compound having the trivalent metal ion M ^{3+ according} to the first step may be one type or a combination of two or more types. When the compound having the trivalent metal ion M ^{3+ according} to the first step is in a powder form, the average particle size of the compound having the trivalent metal ion M ³⁺ is preferably 0.005 to 0.1 μm, particularly preferably. 0.01 to 0.09 μm. In addition, the compound having the trivalent metal ion M ^{3+ according} to the first step is in the form of a sol obtained by adding a solvent such as pure water in a powder form, or by adding a solvent other than water such as ammonia water. It can mix in the state of what was made.

In the present invention, the average particle size of the compound having titanium dioxide, barium carbonate, and trivalent metal ion M ³⁺ is the particle size of the primary particles, and is determined based on a scanning electron micrograph.

In the first step, the method of mixing titanium dioxide, barium carbonate, and a compound having a trivalent metal ion M ³⁺ is not particularly limited, and means for wet mixing include ball mill, pin mill, bead mill, disper mill, A mixing method using a mixing means such as a homogenizer, a vibration mill, an attritor or the like can be mentioned, and examples of the dry mixing means include a high speed mixer, a super mixer, a turbo sphere mixer, a Henschel mixer, a nauter mixer, a ribbon blender, etc. And a mixing method using the mixing means.

  In the first step, the mixing ratio of titanium dioxide and barium carbonate is such that the molar ratio (Ba / Ti) of barium atoms to titanium atoms is 0.990 to 1.010, preferably 0.995 to 1 in terms of atoms. The mixing ratio is 0.005.

  The ratio (M / Nb) of the total number of moles of metal atoms M to the number of moles of niobium atoms in the raw material mixture in the first step is 1 to 3, preferably 1 to 2.75. The ratio of the total number of moles of metal atoms M to the number of moles of niobium atoms in the raw material mixture (M / Nb) is in the above range, so that barium titanate is made semiconducting and titanium dioxide obtained by the sulfuric acid method Even as a raw material, barium titanate having excellent dielectric properties can be obtained. The number of moles of niobium atoms in the raw material mixture is the number of moles of niobium converted into atoms in the raw material mixture, and the total number of moles of metal atoms M in the raw material mixture is the number of moles of niobium atoms in the raw material mixture. It is the total number of moles in terms of atoms of M present.

  The ratio (M / S) of the total number of moles of metal atoms M to the number of moles of sulfur atoms in the raw material mixture according to the first step is preferably 1 to 10, particularly preferably 2 to 9. Since the ratio (M / S) of the total number of moles of metal atoms M to the number of moles of sulfur atoms in the raw material mixture is in the above range, grain growth is suppressed, so that fine barium titanate is obtained. The number of moles of sulfur atoms in the raw material mixture is the number of moles of sulfur in the raw material mixture in terms of atoms.

In the first step, in addition to the compound having titanium dioxide, barium carbonate, and the trivalent metal ion M ³⁺ , the compound having a metal atom other than the metal atom M as necessary, as long as the effects of the present invention are not impaired. May be mixed. In the first step, Na, Mg, Ca, Zr, Si, P, Sr, Mn, and the like are contained as necessary in addition to the compound having titanium dioxide, barium carbonate, and the trivalent metal ion M ^3+. You may mix a compound.

  In the first step, various raw materials are mixed to obtain a raw material mixture. The raw material mixture obtained by performing the first step is composed of a sulfur atom, a niobium atom, and a metal atom M (M is aluminum, iron, gallium, And one or more elements selected from yttrium, indium, antimony, bismuth, lanthanum, neodymium, and samarium.). The sulfur atom, niobium atom, and metal atom M in the raw material mixture are derived from the raw material mixed in the first step. And the ratio (M / Nb) of the total number of moles of metal atoms M to the number of moles of niobium atoms in the raw material mixture obtained in the first step is 1 to 3, preferably 1 to 2.75. The raw materials and their mixing amounts are selected.

  In the first step, the sulfur atom content in the barium titanate obtained by performing the second step is 500 ppm by mass or less, preferably 10 to 400 ppm by mass, and the niobium atom content is 1 to 1000 ppm by mass. Preferably, the raw materials and the mixed amount thereof are selected so that the content of the metal atom M is preferably 10 to 800 ppm by mass, and more preferably 1 to 1200 ppm by mass, and particularly preferably 10 to 1000 ppm by mass. The sulfur atom content in the barium titanate obtained by performing the second step is 500 ppm by mass or less, preferably 10 to 400 ppm by mass, and the niobium atom content is 1 to 1000 ppm by mass, preferably 10 to 800 ppm by mass. In addition, by mixing the raw materials so that the content of the metal atom M is preferably 1 to 1200 mass ppm, particularly preferably 10 to 1000 mass ppm, it has a fine particle diameter and excellent dielectric properties. Barium titanate is obtained.

  Moreover, at a 1st process, a raw material and those mixing amount are selected so that ratio (M / S) of the total number of moles of the metal atom M with respect to the number of moles of the sulfur atom in the obtained raw material mixture may be set to 1-10. It is particularly preferable to select the raw materials and the mixing amount thereof so as to be 2-9. When the ratio (M / S) of the total number of moles of metal atoms M to the number of moles of sulfur atoms in the raw material mixture is 1 to 10, preferably 2 to 9, grain growth in the second step to be described later Can be suppressed, and fine barium titanate can be obtained.

  Most of sulfur and niobium in barium titanate are derived from sulfur and niobium contained in titanium dioxide which is a mixed raw material in the first step. Therefore, content of the sulfur atom in the titanium dioxide which concerns on a 1st process becomes like this. Preferably it is 1-1000 mass ppm, Most preferably, it is 10-900 mass ppm. When the content of the sulfur atom in the titanium dioxide according to the first step is in the above range, barium titanate having a fine particle diameter is obtained. On the other hand, if the content of sulfur atoms in titanium dioxide exceeds the above range, tetragonal barium titanate is difficult to obtain and the dielectric properties are lowered. Further, the content of niobium atoms in the titanium dioxide in the first step is preferably 1 to 2000 ppm, particularly preferably 10 to 1500 ppm. Even if the content of niobium atoms in the titanium dioxide in the first step is within the above range, according to the present invention, barium titanate having excellent dielectric properties can be obtained. The reason for this is not clear, but it is considered that the presence of pentavalent niobium in comparison with tetravalent titanium makes it difficult to balance the valence and leads to the semiconductorization of barium titanate. For example, by adding trivalent metal M, pentavalent niobium and trivalent metal M (the total valence is octavalent) exist for tetravalent titanium. Therefore, the present inventors have inferred that barium titanate can be made semiconductive and the influence on dielectric properties can be reduced.

The titanium dioxide according to the first step is preferably titanium dioxide obtained by a sulfuric acid method. The sulfuric acid method refers to titanium oxyhydroxide (TiO (OH) ₂ ) obtained by hydrolyzing titanium oxysulfate (TiOSO ₄ ) produced by reaction with concentrated sulfuric acid using ilmenite ore (FeTiO ₃ ) as a raw material. In this method, powdery titanium dioxide is obtained by pulverizing after firing. Titanium dioxide obtained by the sulfuric acid method contains niobium derived from production raw materials and sulfur derived from sulfuric acid used in the production process.

  The second step is a step of obtaining barium titanate by firing the raw material mixture obtained by performing the first step.

  In the second step, the firing temperature when firing the raw material mixture is 800 to 1200 ° C, preferably 850 to 1150 ° C, and the firing time is preferably 1 to 50 hours, particularly preferably 3 to 35 hours. It is. Sintering can be performed while suppressing excessive grain growth of the primary particles of barium titanate when the firing temperature and firing time are within the above ranges.

 In the second step, the firing atmosphere when firing the raw material mixture is not particularly limited, and firing can be performed in the air.

  In the second step, after firing the raw material mixture once, the firing may be repeated once or a plurality of times as necessary.

  After performing the second step, the barium titanate obtained by firing may be pulverized or pulverized by a pulverizing means such as a ball mill, a bead mill, an optimizer, or an airflow pulverizer, if necessary.

The barium titanate obtained by carrying out the method for producing barium titanate of the present invention comprises a sulfur atom, a niobium atom, and a metal atom M (M is aluminum, iron, gallium, yttrium, indium, antimony, bismuth, lanthanum, neodymium). And one or two or more elements selected from samarium), and the content of sulfur atoms is 500 ppm by mass or less, preferably 10 to 400 ppm by mass, and the content of niobium atoms The amount is 1 to 1000 ppm by mass, preferably 10 to 800 ppm by mass, and the ratio (M / Nb) of the total number of moles of metal atoms M to the number of moles of niobium atoms is 1 to 3, preferably 1 to 2.75. It is. Moreover, in the barium titanate obtained by performing the method for producing barium titanate of the present invention, the ratio (M / S) of the total number of moles of metal atoms M to the number of moles of sulfur atoms is 1 to 10, preferably 2 to 9. It is. The barium titanate obtained by carrying out the method for producing barium titanate of the present invention preferably has an average particle size of 0.01 to 0.8 μm, particularly preferably 0.05 to 0.5 μm, and BET a specific surface area of 1 to 30 g / ^{m 2,} preferably from 1.5 to 20 / ^{m 2.}

In the method for producing barium titanate of the present invention, the presence of a compound having a trivalent metal ion M ³⁺ in the raw material mixture allows the raw material mixture, in particular, titanium dioxide to contain niobium, A decrease in dielectric characteristics due to niobium can be suppressed. That is, in the method for producing barium titanate according to the present invention, the compound having the trivalent metal ion M ³⁺ is present in the raw material mixture, so that even if niobium is contained in the raw material mixture, the dielectric properties are excellent. Barium titanate can be obtained.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. In addition, the characteristic in an example was measured with the following method.
(1) BET specific surface area Determined by the BET method.
(2) Average particle diameter The diameter was measured about 1000 primary particles arbitrarily extracted by a scanning electron microscope (SEM) photograph, and the average value thereof was defined as the average particle diameter.
(3) Measurement of niobium content The niobium content was measured by IPC emission spectroscopy.
(4) Measurement of sulfur content The sulfur content was measured by a fluorescent X-ray elemental analysis (XRF) method.

Moreover, the following samples were used in the examples and comparative examples.
<Barium carbonate>
Commercially available barium carbonate having physical properties of a BET specific surface area of 3.93 m ² / g and an average particle size of 0.35 μm (primary particles) was used.
<Titanium dioxide A>
Commercially available titanium dioxide having physical properties of a BET specific surface area of 9.09 m ² / g and an average particle diameter of 0.745 μm (primary particles) was used. The titanium dioxide had a niobium content of 881 ppm by mass and a sulfur content of 83 ppm by mass.
<Titanium dioxide B>
Commercially available titanium dioxide having physical properties of a BET specific surface area of 6.60 m ² / g and an average particle size of 0.590 μm (primary particles) was used. The niobium content and sulfur content of the titanium dioxide were below the detection limit.
<Aluminum nitrate gel>
Pure water, aluminum nitrate nonahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and ammonia water (manufactured by Wako Pure Chemical Industries, Ltd.) are mixed at a mass ratio of 113: 1: 17, and stirred to mix aluminum nitrate. A gel was obtained.
<Alumina sol>
Pure water and aluminum oxide (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed at a mass ratio of 833: 1 and stirred to obtain an alumina sol having a solid content concentration of 0.12% by mass.

Example 1
To 35 L of pure water, 12.45 kg of the barium carbonate and 5 kg of the titanium dioxide A were added. To this, 2.32 kg of the aluminum nitrate gel was added to obtain a raw material mixed slurry. This slurry was wet mixed by a ball mill (zirconia beads having a bead diameter of 1 mm) for 6 hours. After the mixing treatment, the mixture was dried at 130 ° C. for 2 hours to obtain a raw material mixture. Table 1 shows the physical properties of this raw material mixture.
Next, the obtained dried material mixture was fired by holding at 1070 ° C. for 6 hours in an electric furnace, cooled to room temperature, and then pulverized by a jet mill to obtain barium titanate powder. Table 2 shows the physical properties of the obtained barium titanate powder.

(Example 2)
The barium titanate powder was prepared in the same manner as in Example 1 except that instead of the aluminum nitrate gel 2.32 kg, the aluminum nitrate gel was 4.64 kg, instead of baking at 1070 ° C., baking at 1085 ° C. Obtained. Table 2 shows the physical properties of the obtained barium titanate powder.

(Example 3)
Barium titanate powder was obtained in the same manner as in Example 1 except that alumina nitrate gel was replaced with 2.32 kg, alumina sol was 4.64 kg, and baking was performed at 1070 ° C. instead of baking at 1070 ° C. . Table 2 shows the physical properties of the obtained barium titanate powder.

(Comparative Example 1)
To 35 L of pure water, 12.45 kg of the barium carbonate and 5 kg of the titanium dioxide A were added to obtain a raw material mixed slurry. This slurry was wet mixed by a ball mill (zirconia beads having a bead diameter of 1 mm) for 6 hours. After the mixing treatment, the mixture was dried at 130 ° C. for 2 hours to obtain a raw material mixture. Table 1 shows the physical properties of this raw material mixture.
Next, the obtained dried material mixture was fired by holding at 995 ° C. for 6 hours in an electric furnace, cooled to room temperature, and then pulverized by a jet mill to obtain barium titanate powder. Table 2 shows the physical properties of the obtained barium titanate powder.

(Comparative Example 2)
To 35 L of pure water, 12.45 kg of the barium carbonate and 5 kg of the titanium dioxide B were added, and 2.32 kg of aluminum nitrate gel was added thereto to obtain a raw material mixed slurry. This slurry was wet mixed by a ball mill (zirconia beads having a bead diameter of 1 mm) for 6 hours. After the mixing treatment, the raw material powder mixture was obtained by drying at 130 ° C. for 2 hours. Table 1 shows the physical properties of this raw material powder mixture.
Subsequently, the obtained dried material powder mixture was fired by holding at 1040 ° C. for 6 hours in an electric furnace, cooled to room temperature, and then pulverized by a jet mill to obtain barium titanate powder. Table 2 shows the physical properties of the obtained barium titanate powder.

(Reference Example 1)
To 35 L of pure water, 12.45 kg of the barium carbonate and 5 kg of the titanium dioxide B were added to obtain a raw material mixed slurry. This slurry was wet mixed by a ball mill (zirconia beads having a bead diameter of 1 mm) for 6 hours. After the mixing treatment, the raw material powder mixture was obtained by drying at 130 ° C. for 2 hours. Table 1 shows the physical properties of this raw material powder mixture.
Subsequently, the dried material powder mixture obtained was fired by holding it at 965 ° C. for 6 hours in an electric furnace, cooled to room temperature, and then pulverized by a jet mill to obtain barium titanate powder. Table 2 shows the physical properties of the obtained barium titanate powder.

<Characteristic evaluation>
5 mass% PVA binder is added to the barium titanate powder obtained in each example, each comparative example, and reference example 1, and is passed through a 250 mesh sieve, and a disk disk having a diameter of 15 mmφ and a thickness of 1 mm is pressure-molded. A molded body was obtained. The molded body was fired at 1245 ° C. for 2 hours. An electrode was applied to the fired molded body with an In—Ga paste, and an insulation resistance value serving as an index for semiconductor formation was obtained. The results are shown in Table 3. The insulation resistance value was measured by applying a voltage of 50 V for 60 seconds using an insulation resistivity meter (SM-8220 manufactured by TOA-DKK).

  As is apparent from the results in Table 3, the insulation resistance value of the molded body obtained from the barium titanate of the example was the same as the insulation resistance value of the molded body obtained from the barium titanate of the reference example. . On the other hand, it was found that the molded product obtained from the barium titanate of the comparative example had a low insulation resistance value, and the molded product was being made into a semiconductor.

Claims (7)

Sulfur atom, niobium atom, and metal atom M (M is one or more elements selected from aluminum, iron, gallium, yttrium, indium, antimony, bismuth, lanthanum, neodymium and samarium). Containing,
The sulfur atom content is 500 mass ppm or less, the niobium atom content is 1-1000 mass ppm,
The ratio of the total number of moles of metal atoms M to the number of moles of niobium atoms (M / Nb) is 1 to 3,
Barium titanate characterized by ^{2. The} barium titanate according to claim 1, having an average particle diameter of 0.01 to 0.5 μm and a BET specific surface area of 1 to 30 m ² / g.   3. The barium titanate according to claim 1, wherein the barium titanate is used for a multilayer ceramic capacitor, a piezoelectric body, an optoelectronic material, a dielectric, a semiconductor, or a temperature sensor. Compound having titanium dioxide, barium carbonate, and trivalent metal ion M ³⁺ (M is one or more selected from aluminum, iron, gallium, yttrium, indium, antimony, bismuth, lanthanum, neodymium and samarium) And a first step of obtaining a raw material mixture,
Baking the raw material mixture to obtain barium titanate;
Having
A process for producing barium titanate, characterized in that   The method for producing barium titanate according to claim 4, wherein the titanium dioxide is titanium dioxide obtained by a sulfuric acid method.   The method for producing barium titanate according to claim 4 or 5, wherein the titanium dioxide contains 1 to 3000 ppm of niobium atoms. 7. The method for producing barium titanate according to claim 4, wherein the ratio (M / Nb) of the total number of moles of metal atoms M to the number of moles of niobium atoms in the raw material mixture is 1 to 3. 8. .