JPH0388770A - Barium titanate-based semiconductor porcelain composition and thermistor - Google Patents

Abstract

PURPOSE:To sufficiently lower resistivity and to obtain excellent dielectric strength and resistance temp. characteristic by using BaTiO3, SrTiO3, CaTiO3 and PbTiO3 as the raw essential components and using skeleton aggregated particle produced by a specified method for at least the former two components. CONSTITUTION:The composition consists essentially of BaTiO3, SrTiO3, CaTiO3 and PbTiO3 and consists of the barium titanate powder in which the average size of the skeleton aggregated particle having open cells and obtained by combining the primary grains of BaTiO3 having <=0.2mum size is controlled to 150-250mum and the content of the secondary grains having <=50mum size to <=5wt.%, the strontium titanate powder in which the average size of the skeleton aggregated particle having open cells and obtained by combining the primary grains of SrTiO3 having <=0.1mum size is controlled to 70-180mum and having 20-30m<2>/g BET specific surface, and others. The essential component contains 45-85mol% BaTiO3, 1-20mol% SrTiO3, 5-20mol% CaTiO3 and 1-20mol% PbTiO3. Furthermore, 0.1-0.3mol% of >=1 kind among the rare-earth elements such as Y, La and Ce, Nb and Sb, 0.006-0.025mol% Mn and 0.1-1mol% SiO2 are incorporated as the semiconductivity imparting agents.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a barium titanate-based semiconductor that has significantly positive temperature characteristics, has sufficiently low specific resistance, and has excellent withstand voltage and temperature coefficient of resistance. This invention relates to MH compositions and thermistors.

[Prior art and problems to be solved] Conventionally, barium titanate-based semiconductor porcelain has barium titanate as its main component, and rare earth elements such as Y, La, and Ce, among Hb and Sb, are added to this as a semiconducting agent. Contains a small amount of at least one kind, which lowers the specific resistance at room temperature and reduces the resistance sudden change point (
Curie point), it exhibits a significantly positive resistance-temperature characteristic.

Normally, barium titanate-based semiconductor porcelain has a Curie point of approximately 12 due to the influence of its main component, barium titanate.
It is around 0℃.

In order to shift the Curie point of such barium titanate-based semiconductor ceramics to a high temperature side, it is known to replace a part of Ba with Pb. In addition, in order to shift the Curie point to a lower temperature side and improve electrical characteristics, a part of Ba is replaced with Sr or Ca, and a part of Tt is replaced with Zr or Sn.
It is also known to replace with etc.

Furthermore, by adding Mn, silica, aluminum, copper oxide, etc. to barium titanate-based semiconductor porcelain, it is possible to improve the resistance temperature change rate after exceeding the Curie point and stabilize the characteristics of semiconductor porcelain. Various attempts are being made. (Tokuko Sho 53-29386, Sho 54-10110
, Japanese Patent Publication No. 63-28324, etc.) By utilizing the characteristics of such barium titanate-based semiconductor porcelain, it is used as a constant temperature heating element, a current limiting element, a temperature controlling element, etc.

In many of the above-mentioned applications, barium titanate-based semiconductor ceramics are required to have as low a resistivity as possible, but as the resistivity of conventional ceramics decreases, resistance temperature characteristics and breakdown For example, if the voltage is extremely degraded, and the resistivity is around 5Ω・(j), the gradient α (Z/°c) of resistivity and resistance temperature characteristics is only about 7, and the breakdown voltage is around 30V/am. [Moto Nishii: Electronic Ceramics, May 88th issue (1988) pp. 22-27] Barium titanate-based semiconductor porcelain with such a low resistivity value has not actually been put into practical use. is the current situation.

[Means for Solving the Problems] In view of the current situation, the present inventors conducted intensive studies to solve the above problems, and as a result, carbonate, which is commonly used as a raw material for barium titanate semiconductor ceramics, was developed. or B a T used as the main component instead of the oxide
103.5rTKO3, CaT)03, PbTiO3, at least BaTto3 and SrTiO3 are produced by a specific method, and have fine and uniform primary particles, and are calcined shell secondary particles with a large average particle size. It was discovered that by using porcelain with a sufficiently low specific resistance of 8 Ω・C@ or less, and with excellent positive resistance-temperature characteristics such as withstand voltage and resistance-temperature characteristics, the present invention has been reached.

That is, the present invention provides BaTiO3, SrTiO3, C
Among the main components of aTt03 and PbTiO3, at least B
aTiO3 is a skeleton secondary particle having open pores in which primary particles of 0.2 μm or less are connected to each other, and the average size is 150
~250 μm, barium titanate powder with 5 wt% or less secondary particles of 50 μm or less, Srτto 3 is 0.1
Secondary particles with an average size of 70 to 180 μm, which have open pores in which primary particles of pm or less are connected to each other.
,, Made of strontium titanate powder with a BET specific surface area of 20 to 30 m2/g, the main component of which is BaTiO3: 45 to 85 mol%
, SrTiO3: 1-20%, CaTiO3
:5 to 20 mol%, PbTi0. : 1 to 20 mol% of the main components as semiconducting agents such as Y, La,
At least one of rare earth elements such as Ce, Hb, and Sb
Seed: 0.1 to 0.3 mol%, further Mn: 0.006 to 0.025 mol%, Si
ng: 0.1 to 1 mol% of barium titanate-based semiconductor ceramic composition, and BaT 103SrTi03 , CaTiO3PbT
Among the main components of iO3, at least BaTiQ is 0.2
A skeletal secondary particle with open pores in which primary particles of less than μm are connected to each other, with an average size of 150 to 250 μm, 50
Barium titanate powder with 5wt% or less of secondary particles of 5 wt% or less, SrTiO3 is a form secondary particle with open pores in which primary particles of 0.1 μm or less are interconnected, and the average size is 70 to 180 μm5BET specific surface area is 20~3M
/g of strontium titanate powder, PbTiO
Formative secondary particles with open pores in which primary particles with a of 0.2 μm or less alternate, and whose size is on average 50 to 150 μm
A barium titanate-based semiconductor ceramic composition consisting of lead titanate powder characterized in that secondary particles with a diameter of 120 μm or less are 5 wt% or less, and whose composition is similar to the above composition;
Furthermore, the specific resistance value is 8 (Ω・cm) or less, and the α value is 9 (z/
``C)'' The present invention provides a barium titanate thermistor characterized by having a withstand voltage of 60 (V/am) or more.

First, we will describe the methods for producing various oxalates, which are the basic raw materials of the present invention.The important points in these methods are to obtain oxalates with as high a purity as possible, and to reduce the concentration of Ba, Sr, and The objective is to obtain a crystal in which the molar ratio of Pb, Ca and Ti is as close to 1 as possible and there is no variation between crystals. Therefore, the purity of raw materials such as oxalic acid, titanium tetrachloride, Ha, Sr, and Pb
In addition to ensuring that the Ca salt is as pure as possible, the reaction vessel is preferably an acid-resistant plastic container such as Teflon to avoid contamination from the reaction vessel, and the final oxalate is an alkaline earth The concentration of other metal impurities other than the It was found that it could be successfully manufactured by using a manufacturing method.

First, let's talk about the production of barium titanate chelate. The reaction is carried out by adding a solution containing titanium tetrachloride and barium chloride to an aqueous solution containing oxalic acid. It is only necessary to set the concentration of barium chelate titanate tetrahydrate to be within the range of 10 to 12-t%. Therefore, the water balance of both solutions can be adjusted to any concentration as long as it is within the set concentration range. However, in order to prevent barium chloride from precipitating in a solution of titanium tetrachloride and barium chloride, the concentration of barium chloride in the solution needs to be 10 wt % or less.

Ba/Ti (mole ratio) is 1.02~ with slightly more Ba
It is necessary to set it to 1.05. When Ba/Ti (molar ratio) is less than 1.02, B of the oxalate produced
If the a/Ti (molar ratio) is less than 0.998, which is undesirable, on the other hand, if the Ba/Ti (molar ratio) is larger than 1305, the Ba/Ti (molar ratio) of the oxalate produced is 1.0. Unreacted Ba that does not change greatly in the vicinity
The molar ratio of oxalic acid/Tt (molar ratio), which is uneconomical due to the large amount of
It is preferable to set the concentration in the range of 3. In addition, the concentration is preferably in the range of 10 to 12 wt% in view of the economical concentration and the shape of the crystals while suppressing the precipitation of other salts.

Furthermore, the addition conditions, stirring conditions, and temperature conditions have a major influence on the crystal size, shape, and particle size distribution of the barium chelate titanate tetrahydrate that is formed, so addition should be done in a shower over as wide a range as possible. If it is not sufficiently dispersed during addition, fine crystals will precipitate, and if it is not added slowly and in small amounts over 4 hours or more, a similar phenomenon will occur, causing deterioration of the physical properties of the final product. The same applies to the stirring state, and although it differs slightly depending on the scale and shape of the container, it is necessary to perform the stirring at at least a peripheral speed of 2.5a+/see.

Next, regarding temperature conditions, the crystallization temperature and temperature fluctuations have a great effect on crystallization and are a major cause of precipitation of microcrystals, so it is necessary to maintain a constant temperature within the temperature range of 55 to 75°C. If the temperature is lower than 55℃, crystals with poor crystallinity will be formed and the Ba/Ti (molar ratio) will be smaller than 0.998, while if the temperature is higher than 75℃, the crystals will be unstable and If the time until filtration is long, Ba/Ti (molar ratio) is 0.998.
This is not desirable because it becomes lower.

The barium titanate oxalate crystals precipitated in this way have a Ba/Ti (molar ratio) of 0.998 to 1.002.
Within this range, the inside of the crystal is stoichiometrically uniform, the crystal grain size is uniform with an average of 100 μm or more, and there are few small crystals.

Next is the method for producing strontium titanate chelate. Compared to barium chelate titanate, Sr/Ti
(molar ratio) tends to be less than 1, so the S
It is necessary to set r/Ti (molar ratio) to 1.2 or more. When the setting Sr/Ti (molar ratio) is smaller than 1.2, the Sr/Ti (molar ratio) of the generated oxalate is 0.99.
A value smaller than 8 is not preferable, but if it is too large, it is not economical, so it is usually set in the range of 1.2 to 1.3. The molar ratio of Scheleric acid/Ti (molar ratio) is preferably set in the range of 2.1 to 2.3 from the viewpoint of yield and economic efficiency. , and the shape of the crystals, the concentration is 10 to 14 wt.
A range of % is preferred.

Furthermore, the addition conditions, stirring conditions, and temperature conditions have a major influence on the size, shape, and particle size distribution of the crystals of strontium oxalate titanate pentahydrate that are formed, so addition should be done in a shower over as wide a range as possible. If the addition is not sufficiently stirred and dispersed, fine crystals will precipitate, and 2.
A similar phenomenon will occur if the Sr/Ti (molar ratio) of the crystals is not added slowly and in small amounts over a period of time to 0.9.
The same applies to the stirring conditions, which are less than 98, which is undesirable, and the stirring conditions must be at least 3.0 s/sec, although they differ slightly depending on the scale and shape of the container.

Next, regarding temperature conditions, the crystallization temperature and its temperature fluctuations have a large effect on crystallization and are a major cause of precipitation of microcrystals, so it is 60 to 80 °C compared to barium titanate oxalate. It is necessary to maintain a constant temperature in a high temperature range, and for the same reason as barium oxalate titanate, Sr/Ti (molar ratio) becomes less than 0.998 whether it is higher or lower than the above range, which is undesirable.

The crystals of strontium titanate chelate thus precipitated also have a Sr/Ti (molar ratio) of 0.998 to 1.
, 002, the inside of the crystal is also stoichiometrically uniform, the crystal grain size is uniform with an average of 70 μm or more, and there are few small crystals.

In the case of strontium titanate oxalate, the yield is as low as about 80 wt% at a reaction temperature of 60-80"C, so the yield can be increased to 90-t% or more by cooling after the reaction. However, cooling Since the Sr/Ti (mole ratio) of the oxalate that is subsequently precipitated changes depending on the cooling rate, the cooling rate must be within the range of 5°C/hr to 30°C/hr.

Furthermore, regarding the manufacturing method of lead titanate Scheler acid, in this case, if titanium tetrachloride is used, lead chloride precipitates will be generated when the lead salt is dissolved, so it is not necessary to use titanium tetrachloride as in the case of barium titanate Scheler acid. method could not be used, so titanium tetrachloride was once neutralized with ammonia to generate a titanium hydroxide gel.
After thorough filtration and washing, it becomes a solution by dissolving it in Scherer's acid, and this solution can be used. In the case of lead oxalate titanate, Pb/Ti (molar ratio)
varies, so it is necessary to keep various conditions constant,
In order to obtain a complete solution and considering the yield during the subsequent formation of sulfuric acid salt, and under conditions where the molar ratio is close to 1, the Scheric acid/Ti (molar ratio) is 2°1 to 2.3, TiO2: 4w
It is necessary to keep it below t%. Considering the total water balance, the concentration of lead oxalate titanate produced is 10~
The concentration of the solution of Ti dissolved in Schereric acid and the concentration of lead nitrate may be set so as to be within this range.

Further, when the concentration of lead titanate schellanate is set to 10 to 18%, it is possible to obtain uniform crystals with a large particle size.

In order to obtain oxalate with a Pb/Ti (molar ratio) close to 1, the set Pb/T t (molar ratio) should be 1.01 to 1.
If the set Pb/Ti (molar ratio) is lower than 1.01, the Pb/Ti (molar ratio) of oxalate will decrease to 0.99 or less, while the set Pb/Ti (molar ratio) When is larger than 1.03, on the other hand, the molar ratio of oxalate becomes 1.01, which is too large. The same applies to the setting Shellacic acid/Tt (molar ratio). Regarding the liquid temperature at the time of 0 reaction, it is necessary to carry out the reaction in the range of 45 to 55 ° C.
Outside this range, the molar ratio becomes lower than 0.99, which is not preferable.

When obtaining lead oxalate titanate, the diffusion state in the liquid has a great influence on the crystalline state, so to ensure as uniform and fast diffusion as possible, the addition should be carried out in a shower state, and the stirring circumferential speed should be at least 2.01/see. It is necessary to do so.

The crystals of lead titanate chelate precipitated in this way also
When the Pb/Ti (molar ratio) is within the range of 0.998 to 1.002, the inside of the crystal is stoichiometrically uniform, the crystal grain size is uniform at an average of 50 μm or more, and there are few small crystals. Become.

Regarding calcium titanate, which is one of the powder compositions of the present invention, Ca/T t (molar ratio), CaCl2 concentration, Scheric acid/Ti (molar ratio) By setting the concentration of the oxalate to be produced, the temperature of the liquid, the addition method, the stirring conditions, etc., it is possible to produce Scheler acid with a Ca/Ti (molar ratio) close to 1 and a similarly large crystal grain size. Calcium titanate can be obtained.

Each oxalate obtained by the above-mentioned method is in a form in which the protons of the organic acid are replaced by metals or metal oxides, and is subjected to ordinary sintering in an atmosphere containing sufficient oxygen. By pre-calcining at a temperature slightly lower than the temperature at which the organic matter is oxidized and decomposed, BaT i03.
Oxides in the form of 5rTt03, PbTiO3, and CaTiO3 are formed, but the crystalline state of the organic matter before decomposition has a large effect on the physical properties of the oxide after firing, such as particle size, particle size distribution, and molar ratio. Moreover, the above-mentioned physical properties greatly influence the electrical properties of the final sintered body.

The calcined body of oxalate obtained in the present invention has homogeneous fine particles of about 0.25 m or less that are lightly sintered to have a bonding force with each other and maintain the shape of the oxalate before decomposition. It has the structure of so-called skeleton particles, and the particles are uniformly distributed without uneven atomic distribution, and it is possible to obtain a sintered body using such a calcined body through the mixing and firing processes described later. As a result, the sintered body itself has a uniform am, and becomes a porcelain having a low resistivity, a high temperature coefficient of resistance, and a high withstand voltage.

First, to specifically describe the pre-calcination of barium oxalate titanate, strontium chelate titanate, and calcium oxalate titanate, each of the obtained oxalates is dried at a temperature that does not allow crystal water to scatter. The resulting hydrated salt is calcined at a temperature that does not carbonize the organic matter and maintains the size of the particles such that a=i. Therefore, it is necessary to carry out firing in an atmosphere that is sufficiently supplied with oxygen in the furnace, but since organic acid salts may cause rapid decomposition and combustion, excessive oxygen is not necessary, and a moderate oxygen atmosphere is necessary. It is preferable to do so. Preliminary firing temperature is 700-90
0°C is preferable, and if it is lower than 700°C, oxidative decomposition will not proceed sufficiently and carbon etc. will remain, which is not preferable.

On the other hand, if the temperature is higher than 900'C, non-uniform grain growth tends to occur, and local abnormal grain growth is often observed, which is not preferable.

The calcined bodies of oxalates obtained in this way, barium titanate and calcium titanate, are skeletal secondary particles with open pores in which primary particles of 0.2 μm or less are connected to each other, and the size is The average particle size is 150 to 250 μm,
The calcined body has a secondary particle diameter of 5 wt % or less and a BET specific surface area of 6 to 1 ion (/g) in which the secondary particles are 50 μm or less in size.

In addition, for the calcined strontium titanate body, 0.1
It is a skeletal secondary particle having open pores in which primary particles of less than μm are interconnected, and its size is on average 70 to 180 μm. In this case, the BET specific surface area of the calcined body produced by the oxalate production method is Powders that vary greatly and exhibit excellent properties for sintered porcelain have a BET specific surface area within the range of 20 to 30 i/g, and the secondary particles of 40 μm or less are also 5% or less.

In the case of lead oxalate titanate, the oxidative decomposition temperature is lower than the above-mentioned oxalates, and grain growth is easy, so the pre-calcination is 6
00 to 800°C is preferable; at temperatures lower than 600'C, oxidative decomposition does not proceed sufficiently and carbon, etc. remain, which is undesirable. On the other hand, at temperatures higher than 800'C, uneven grain growth occurs. The lead oxalate titanate calcined body obtained in this way also has open pores in which primary particles of 0.2 μm or less are interconnected. With vestigial secondary particles,
The average size is 50-150 μm, the proportion of secondary particles of 20 μm or less is 5% or less, and the BET specific surface area is 6-15%.
The calcined body has a uniform secondary particle size of LOrrr/g.

The oxalate calcined body obtained by the above method is used as a raw material, and is mixed and fired by the method described later. However, in this case, it is not necessary to use all oxalate calcined bodies. , at least BaTiO3, SrTiO
Regarding 3, use a calcined body of oxalate.

In this case, the other PbTiO3 and CaTl03 may be produced by the so-called ordinary solid phase method, and usually their respective raw material powders, for example, in the case of PbTiO3, PbO and T
Pb produced by mixing, firing, and pulverizing iO2
CaTiO3 produced in the same manner as TiO3 is used by mixing with oxalate calcined body, but the average particle size and impurity concentration must be similar to those of the oxalate calcined body. The particle size must be 2 μm or less, and the amount of metal impurities other than alkaline earth metals must be 100 pp+m or less.

Next, the composition of the present invention will be explained. The present invention comprises BaTiO3-5rTu03, CaTj as the main components.
03PbTi03 is BaTiO3: 45-85 mol%
, SrTiO3: 1 to 20 mol%, CaTiO3:
5 to 20 mol%, PbTi03 = 1 to 20 mol%, and at least one of rare earth elements such as Y, La, and Ce, Hb, and Sb as a semiconducting agent.
．． 1 to 0.3 mol%, further Mn2 0.006 to 0.0
25 mol%, St, 02: 0.1 to 1 mol% is added.

The main components of the present invention are BaTiO3, SrTiO3, and Ca.
TiO3, PbTiO3 four-class porcelain is made by replacing a part of Ba in barium titanate with Ca, Sr, and Pb at the same time. When used alone, Pb and Sr shift the Chieri point to the high-temperature and low-temperature sides, respectively, and these Ca and Sr.

It is known that by including PB as the main component in a coexisting state, the withstand voltage value increases and the durability against large rush currents improves.However, in the conventional method, the specific resistance is 8 (
No material with excellent withstand voltage characteristics has been obtained with a voltage resistance of Ω·cm or less.

The main component of the present invention is BaTiO3: 45 to 85 mol%
, 5rTj03: 1 to 20 mol%, CaTiO3
: 5-20 mol%, PbTiO3: 1-20 mol%
However, the reason why the main components are limited to the above range is as follows.

First, if BaTiO3 is less than 45%, it becomes difficult to make it into a semiconductor and the specific resistance becomes high. On the other hand, if it exceeds 85%, it is not preferable because the electrical characteristics deteriorate.

SrT! If 03 is less than 1 mol%, the particles of the sintered body will become coarse, and the effect of improving electrical properties will not appear.
If it exceeds mol%, partial grain growth will occur and electrical characteristics will deteriorate.

If CaTiO3 is less than 5 mol%, the withstand voltage characteristics are not excellent, and if it exceeds 20 mol%, the voltage withstand characteristics are deteriorated.

Regarding PbTiO3, if it is less than 1 mol%, the electrical properties are not satisfactory, and if it exceeds 20 mol%,
Since PB scatters during heating, it becomes difficult to sinter and make it difficult to convert into a semiconductor.

At this time, if the molar ratio of the sum of the main components Ba, Sr, Ca, Pb and Ti is adjusted within the range of 0.99 to 1.03, it will hardly affect the physical properties of the manufactured porcelain. We can manufacture products that do not cause any damage.

In order to manufacture barium titanate-based semiconductor ceramics, it is necessary to contain a small amount of a semiconducting agent, such as rare earth elements such as Y, La, Ce, and Nb.

It is sufficient to add or contain at least one of the following in an amount of 0.1 to 0.3 mol%. If the amount added is less than 0.1 mol%, semiconductor formation will not be successful, and it is more than 0.3 mol%. On the other hand, the specific resistance is high (which is undesirable), and when adding
Preferably, it is added in the form of oxalate or oxide.

Furthermore, by adding Mn and SiO2 to the above composition, the resistance temperature characteristics can be improved.

In the present invention, compared to the solid phase method, a trace amount of Mn, 51
A large improvement in properties was achieved with the addition of 0 g, and it is thought that because the oxalate calcined body was used as the main raw material, the additive was dispersed very uniformly and the above effect was achieved.

In this case, the amount of Mn added is Mn: 0.006 to 0
．． 025 mol %, and these proportions are included in the porcelain.

By adding My+, the rate of change in resistance temperature can be significantly increased in the positive resistance temperature characteristic exceeding the Curie point.

The temperature coefficient of resistance (
Hereinafter, the α value will be abbreviated as 〉. If the Mn content is less than 0.006 mol %, the α value will become small and the withstand voltage characteristics will deteriorate. On the other hand, if Mn is more than 0.025 mol%, the α value will increase, but the specific resistance at room temperature will increase, and when used at low voltage, it will not work, which is not preferable.
N may also be added in the form of oxalate or oxide.

Next is the addition of SiO□, the amount of which is 5 inches.
2: A range of O, L = 1 mol% is preferred.

The addition of SiO2 suppresses changes in resistivity caused by slight fluctuations in the addition of the semiconducting agent, and aims to achieve a low resistivity value at room temperature.
, If it is less than 1 mol%, grain growth tends to occur, the withstand voltage characteristics deteriorate, and the α value becomes small, while if 5in2 is more than 1 mol%, the specific resistance becomes high, which is undesirable.
When adding SiO2, it is sufficient to use an oxide with a particle size as small as possible.

Weigh each raw material powder in the proportions described above, and use a ball mill pot made of plastic, etc., which is difficult to mix with metal impurities, and balls made of zirconia, etc., which are high in density and do not affect the electrical characteristics even if a small amount of impurities are mixed in. Use for mixing and crushing.

In this case, a liquid such as water or a solvent may be added to increase the crushing effect. After this step, the liquid is removed,
Granulation is carried out, and 0.3 to 1. Molding is carried out at a pressure of 100 t/cm". After molding, the temperature is raised at 5 to 10°C/sin.
After firing at 1300 to 1400°C for 5 minutes to 2 hours, the temperature is lowered at the same rate as the temperature rise to obtain the porcelain of the present invention. If the molding pressure is too low than the specified value, the specific resistance will increase, while if it is too high, the specific resistance will decrease, but the α value will decrease, which is undesirable.
If the heating rate is too slow, the resistivity will increase; if the temperature is too high, the resistivity will decrease, but the α value will also drop, which is not desirable. Regarding the firing temperature, if the temperature is too low or too high, the resistivity will increase, which is not desirable. .

The porcelain of the present invention produced by the method described above has a density of 5
．． 2 to 5.6 g/c*3, specific resistance value is 8 (Ω・C)
Below, the α value is 9 (z/'C) or more and the withstand voltage is 60 (
It has a low specific resistance of V/1m) or more, has a high withstand voltage, and
It becomes an excellent barium titanate semiconductor porcelain with a high value.

In this way, the reason why it has excellent electrical properties due to the use of materials manufactured from oxalate as the main component is that the purity of the raw materials is the total metal content excluding alkaline earth elements. Since the elemental content is very high at less than 1100pp, it is easy to control the properties by adding trace elements, and the effect of improving the properties is large.The structure in the porcelain is well-organized with a dalein size of less than 10μm and an average size of approximately 5μm. It is thought that this is due to the uniform microstructure consisting of a sintered body with a grain size of 100%, which improves the withstand voltage characteristics.

Furthermore, since the oxalate calcined body, which is the main component, is a skeleton particle in which fine and uniform primary particles with appropriate strength are combined, the skeleton particles are sequentially crushed and mixed during mixing and crushing, so it is very mixable. As a result, each atom is uniformly dissolved in solid solution during sintering, and when made into porcelain, the distribution of atoms becomes more uniform, and there are no local changes in the characteristics within the porcelain, and the overall characteristics are uniform. However, as a result of actually examining various conditions to obtain the most optimal conditions for the selection of raw materials, manufacturing method, mixing and crushing method, sintering method, etc. of the present invention,
The overall effect was that we were able to obtain porcelain with such outstanding electrical properties.

These are extremely useful as constant-temperature heating elements, current limiting elements, temperature control elements, and the like.

[Examples] Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Tt (OH
) 27.6wt% Ti ion, IC! Tttl liquid 6 containing 32.8 wt% Cl ions in terms of
50 kg of barium chloride dihydrate, 389 kg of barium chloride dihydrate, and 2980 kg of pure water were slowly mixed to prepare a solution for addition.

- In a rubber-lined tank B with a large capacity of 7 m2, 4.29 kg of oxalic acid was dissolved in 2055 kg of pure water, and the temperature was raised to 60°C and maintained at that temperature.

Ha/TI (molar ratio) at this time = 1.03, oxalic acid/
Ti (molar ratio>=2.2, BaCl2 =8.25
It was wt%.

The solution was added from tank A to tank B using a charge pump, and about 200 holes were provided at the tip of a pipe, and the solution was added to the liquid surface in a shower-like manner.

Stirring at this time was performed by rotating a stirring blade having two flat blades at 50 rpm, and the peripheral stirring speed at this time was 2.9 m/sec.
The addition time was 4 hours.

Further, the set concentration of barium titanate chelate produced at this time was 11% and 117%.

After the addition is complete, the reaction solution is centrifuged! After filtering and washing through 11m filter, the product was dried at 50° C. to obtain 592 kg of crystals of barium titanate chelate. The yield at this time was 88
．． 3wt%, its Ba/TK (mole ratio) is 0.999
Met.

The obtained powder was placed in a porcelain crucible and heated to 900°C in air.
, for 2 hours to obtain calcined barium titanate powder.

The obtained powder contained no more than 10 ppm of metal impurities other than alkaline earth metals, had an average particle size of 200 μm, and had a grain size of 50 μm.
The particles below am were about 2 wt%. Figure 2 shows scanning electron micrographs (SE) of the powder obtained at this time (4), and Figure 3 shows transmission electron micrographs (TEM) of a portion of the powder obtained to observe the state of the primary particles. As shown in the figure.

Example 2 Ti(OH) was placed in a rubber-lined tank A with a capacity of 5 d.
), 39.9ivt% of T1 ions, 1 (31.9% of C1 ions in terms of CI), Til solution 51
6 kg of strontium chloride hexahydrate, 516 kg of strontium chloride hexahydrate, and 1590 kg of pure water were slowly mixed to prepare a solution for addition.

- Dissolve 429 kg of oxalic acid in 2147 kg of pure water in rubber-lined tank B with a large capacity of 7 d, and lower the temperature to 7 d.
The temperature was increased to 5°C and maintained at that temperature.

At this time, Sr/Ti (molar ratio) = 1.25, oxalic acid/Ti (molar ratio) = 2.2.5rCh = f2. Owt
%Met.

The solution was added from tank A to tank B using a charge pump, and the solution was added by making about 200 holes at the tip of a vibrator and adding the solution to the liquid surface in a shower-like manner.

For stirring at this time, a stirring blade having two flat blades was used, and the stirring circumferential speed at this time was 4.1 m/sec.
The solution during the reaction was maintained at 75°C, and the addition time was 2.5 yen.
It was between f. Further, the set concentration of strontium oxalate titanate produced at this time was 12 wt%.

After the addition was completed, the reaction solution was cooled to room temperature at a rate of 20°C/hr, filtered and washed with a centrifuge, and further
By drying at 0° C., 600 kg of crystals of strontium titanate chelate pentahydrate were obtained. Sr/T of this oxalate [(molar ratio)=0.999, yield is 93
-t%.

The obtained powder was placed in a porcelain crucible and heated at 900° in air.
Strontium titanate calcined powder was obtained at the bottom of the pit using Cl2hr. The obtained powder contains all metal impurities other than alkaline earth metals at 10 ppm or less, and the average particle diameter of the secondary particles is 150 μm, and the secondary particles with a diameter of 150 μm or less are 2.5 wt.
%, BET specific surface area was 26°0/g.

Example 3 A solution of TiC1m = 10 wt% was cooled to 40°C or below and neutralized with an ammonium aqueous solution until the pH reached 7 to obtain gel-like titanium hydroxide, which was then filtered and washed with pure water. do. The gel after washing was immediately dissolved with oxalic acid, and after measuring the concentration of Ti ions, the concentration of Ti ions was reduced to 2.4 wt% using pure water and oxalic acid.
, oxalic acid/Ti (mole ratio was adjusted to >=2.15, and 2378 kg of this solution was transferred as an addition solution to a rubber-lined tank A with a capacity of 7M.Meanwhile, it was transferred to a rubber-lined tank B with a capacity of 5M. Lead nitrate 402 kg and pure water 1
086 kg was added to form a solution. At this time, Pb/Ti (molar ratio) was 1.02, and the set concentration of lead oxalate titanate to be produced was 16.0 wt%.

The solution was added from tank A to tank B using a charge pump, and about 200 holes were provided at the tip of a pipe, and the solution was added to the liquid surface in a shower-like manner.

For stirring at this time, a stirring blade having two flat blades was used, and the peripheral stirring speed at this time was 2.0 s/sec.

The solution during the reaction was maintained at 50 °C, and the addition time was 2.0
It was time.

After the addition was completed, the solution was filtered and washed, and further dried at 50°C to obtain lead oxalate titanate tetrahydrate. Yield is 97.0w
t%, Pb/Ti (molar ratio) of lead titanate shalerate is 0
．． It was 998.

The obtained powder was placed in a porcelain crucible and heated to 600℃ in air.
, for 2 hours to obtain a calcined powder of lead titanate. The obtained powder has metal impurities other than alkaline earth metals of 10 ppm+ or less, and the average particle size of the secondary particles is 140 μm.
m, secondary particles with a size of 50 μm or less were 3 wt%.

Examples 4 to 19 Main component raw materials include BaTiO3, SrTiO3, P
For bTiO3, the oxalate calcined powder produced in Examples 1 to 3 was used, and for CaTl03, CaCO3 and Tl
Manufactured from O2 by solid phase method, all metal impurities other than alkaline earth metals are 10 ppm or less, and the average particle size is 0.5
Powder of μm was used.

Next, lanthanum oxide, manganese shellate, and silicic anhydride were used as trace components, and for lanthanum oxide and silicic anhydride, particles having a particle size of 10 μm or less were used. These raw materials were blended to the m-acid ratio shown in Table 1, a binder was added, and a 501 polyethylene ball mill bot and zirconia balls were used.
Alcohol solvent was added and 24 hour mixing was performed.

After dehydrating and drying this and granulating it, the molding pressure was 1000 kg/
- The bottom was shaped like a disk. Furthermore, this is heated to 1350°C12
After firing for a period of time, a disk-shaped sintered body having a diameter of 13 mm and a thickness of 2.5 mm was obtained. An In-Ga alloy electrode was provided on the amphibian surface of the obtained semiconductor porcelain, and this was used as a sample. For these samples, the Curie point, resistivity value, α
The value and withstand voltage value were measured. The results are shown in Table 1.

Comparative Examples 1 to 9 In each method of Examples 1 to 3, oxalates were produced by changing only one condition, calcined in the same manner, and the calcined powder was used. Example 4~
Porcelain was manufactured using the same method as in No. 19, and its electrical properties were measured.

Table 2 shows the conditions and electrical characteristics at that time.

Comparative Examples 1O to 24 The same operations as in Examples 4 to 1 were performed except that the composition of the raw materials was set to the proportions shown in Table 3. Table 3 shows the physical properties of the obtained porcelain.

Comparative Example 25.26 As a raw material, its main components include BaCO3 and CaCO3.
, SrCO3, Pb30a, Tt02, La203 as a semiconductor agent, MnCO3,S as an additive.
After blending iO2 to have the porcelain composition shown in Table 3,
Exactly the same operations as in Examples 4 to 19 were performed.

Table 3 shows the composition of each component in this comparative example and the physical property values of the obtained porcelain.

In the above-mentioned characteristics, the withstand voltage is the voltage that is gradually increased after a voltage is applied to the sample, and indicates the maximum applied voltage value before the sample breaks down.

Figure 1 shows the resistance-temperature characteristics of the porcelains obtained in Example 10, Example 18, and Example 19. Both resistivity and temperature characteristics can be maintained at low specific resistance and high α value.

rEffect of the invention] Barium titanate-based semiconductor porcelain &lI obtained by sintering secondary particles having a unique shape made of fine primary particles with uniform particle size of the present invention using raw materials can be used in a wide range of applications such as current limiting elements, temperature control elements, constant temperature heating elements, etc., and has a specific resistance value of 8 (Ω・C 廖) or less and an α value of 9 (Z/"C). ), it exhibits excellent electrical properties such as low resistance and high withstand voltage of 60 (V/+em) or higher, and a high α value, so it is suitable for various applications as a current limiting element, especially for low voltages. It can be applied to various purposes.

[Brief explanation of drawings]

FIG. 1 is a resistance-temperature characteristic diagram of the barium titanate-based semiconductor ceramic composition of the present invention. 0 00 50 00 Temperature (°C) Procedural Amendment April 18, 2015 2, Title of Invention: Barium titanate-based semiconductor ceramic composition and thermistor correction representative: Wada Kakuhei 4゜

Claims (3)

[Claims] (1) BaTiO_3, SrTiO_3, CaTiO
_3, among the main components of PbTiO_3, at least BaT
Primary particles with an iO_3 of 0.2 μm or less are secondary particles with open pores connected to each other, and the average size is 150~
250μm, barium titanate powder with 5wt% or less of secondary particles of 50μm or less, SrTiO_3 is 0.1μ
It is composed of strontium titanate powder, which is a skeletal secondary particle having open pores in which primary particles of less than The composition of the ingredients is BaTiO_
3: 45-85 mol%, SrTiO_3: 1-20 mol%, CaTiO_3: 5-20 mol%, PbTiO_3
: 1 to 20 mol %, and at least one of rare earth elements such as Y, La, Ce, Nb, and Sb is added as a semiconducting agent to the main component.
1 to 0.3 mol%, further Mn: 0.006 to 0.025 mol%, SiO_
2: A barium titanate-based semiconductor ceramic composition characterized by having a composition of 0.1 to 1 mol%. (2) BaTiO_3, SrTiO_3, CaTiO
_3, among the main components of PbTiO_3, at least BaT
Primary particles with an iO_3 of 0.2 μm or less are interconnected secondary particles with open pores, and the average size is 150~
Barium titanate powder, SrTi, characterized in that secondary particles of 250 μm and 50 μm or less are 5 wt% or less
O_3 is a skeletal secondary particle with open pores in which primary particles of 0.1 μm or less are connected to each other, and the average size is 70 to 18
Strontium titanate powder, PbT, characterized by having a BET specific surface area of 0 μm and a BET specific surface area of 20 to 30 m^2/g.
Primary particles with an iO_3 of 0.2 μm or less are secondary particles with open pores connected to each other, and the average size is 50 to 1
Made of lead titanate powder characterized by secondary particles of 50 μm and 20 μm or less being 5 wt% or less, the main component of which is BaTiO_3: 45 to 85 mol%.
, SrTiO_3: 1 to 20 mol%, CaTiO_3:
5 to 20 mol%, PbTiO_3: 1 to 20 mol%, and at least one of rare earth elements such as Y, La, Ce, Hb, and Sb is added as a semiconducting agent to the main component.
1 to 0.3 mol%, further Mn: 0.006 to 0.025 mol%, SiO_
2: A barium titanate-based semiconductor ceramic composition characterized by having a composition of 0.1 to 1 mol%. (3) Specific resistance value is 8 (Ω・cm) or less, α value is 9 (%
A barium titanate thermistor having a withstand voltage of 60 (V/mm) or more.