JPH0465356A - Raw material powder for barium titanate series semiconducting ceramic composition and ceramic composition - Google Patents

Abstract

PURPOSE:To provide a raw material powder for semiconductor ceramics having low resistance and high dielectric strength by providing a composition which is composed principally of BaTiO3, SrTiO3, CaTiO3, PbTiO3 having respectively specified shapes and with which semiconductor forming agent and trace amounts of CuO, Mn, and SiO2 blended. CONSTITUTION:Principle components which consists of (A) 45-85 mole% of BaTiO3 powder consisting of secondary grains formed by connecting <=0.2-mum primary grains and having 150-250mum average grain size, <=5 wt.% <=50-mum grains and open pores, (B) 1-20 mole% of SrTiO3 powder consisting of secondary grains formed by connecting <=0.1-mum primary grains and having 70-180mum average grain size, 20-30m<2>/g BET specific surface area, and open pores, (C) 5-20 mole% of CaTiO3, and (D) 1-20 mole% of PbTiO3 are produced. The raw material powder for barium titanate series semiconducting ceramic composition can be produced by incorporating 0.05-0.14 mole% semiconductor forming agent consisting of the oxide of Y, La, Ce, Nb, or Sb, 0.005-0.03 mole% CuO, 0.005-0.03 mole% Mn, and 0.5-2 mole% SiO2 into the above principle components.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a barium titanate-based semiconductor M! which has a significantly positive temperature characteristic, has a sufficiently low specific resistance, and has an excellent temperature coefficient of resistance. The present invention relates to a L-pot composition and a powder serving as a raw material thereof.

[Prior art and problems to be solved 1 Conventionally, barium titanate-based semiconductor porcelain has barium titanate as its main component, and at least one of rare earth elements such as Y, La, and Ce, Nb, and Sb is added as a semiconducting agent. It contains a small amount of one kind, and has the characteristics of lowering the specific resistance at room temperature and exhibiting a significantly positive resistance-temperature characteristic when the resistance abruptly changes point (Curie point) is exceeded.

Normally, barium titanate-based semiconductor porcelain has a cu1 point of approximately 1 due to the influence of its main component, barium titanate.
It's around 20°C.

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 Ti is replaced with Zr or Sn.
It is also known to replace with

In addition, barium titanate-based semiconductor porcelain with silica and silica,
Various attempts have been made to improve the temperature change rate of resistance after exceeding the Curie point and to stabilize the characteristics of semiconductor ceramics by adding alumina, copper oxide, etc.

(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.

However, 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 When the voltage deteriorates extremely, for example, when the specific resistance is about 5 Ωcm, the temperature coefficient of resistance, that is, the slope of the resistance temperature characteristic [hereinafter α
Abbreviated as value. ] (''/''C) is only about 7, and the breakdown voltage remains low at around 30 V/ms [Moto Nishii: Electronic Ceramics, May 888 issue (1988
) pp22-27] Currently, barium titanate semiconductor ceramics having such a low resistivity value have not been put into practical use.

[Means for Solving the Problems] In view of the current situation, the present inventors have conducted extensive studies to solve the above problems, and have found that carbonate or oxide, which is commonly used as a raw material for barium titanate semiconductor ceramics, has been developed. BaTiO3, which is used as the main component of Muko instead of things,
Among SrTiO3, CaTiO3, PbTiO3, at least BaTiO], SrTiO3, PbTiO3
calcined powder of oxalate produced by a specific method,
That is, by using skeletal secondary particles that have fine and uniform primary particles and a large average particle size, and adding semiconducting agents, Mn, and SiO□ as additives to the powder, low resistivity and other electrical properties can be achieved. It was discovered that a semiconductor ceramic composition excellent in
25062, and also in a system that uses a semiconductor agent, CuO1Si02, as an additive.
It was discovered that similarly excellent electrical characteristics could be obtained, and a proposal was made in Japanese Patent Application No. 2-137667.

The present inventors conducted further studies and found that by simultaneously adding other additives such as a semiconducting agent, apertures, and CuO1SiO□ to the above-mentioned main components, the specific resistance was extremely low at 10Ω・C1 or less, and the temperature coefficient of resistance was further improved. The present invention was achieved by discovering that porcelain having excellent positive resistance temperature characteristics can be obtained.

That is, the present invention provides BaTiO3, SrTiO3, C
Among the main components of aTiO3 and PbTiO3, at least Ba
TiO3, SrTiO3, and PbTiO3 are: (1) BaTiO3: A skeletal secondary particle having open pores in which primary particles of 0.2 μm or less are connected to each other, and the size thereof is an average particle size of 150 to 250〃m, and 50 μm. BaTiO3 powder containing 5 wt% or less of the following secondary particles: ■SrTiO3: 0. SrTiO3 powder, which is a skeletal secondary particle having open pores in which primary particles of lum or less are connected to each other, has an average particle size of 70 to 180 μm, and has a BET specific surface area of 20 to 30 m2/g;
(3) PbTiO3: Primary particles of 0.2 μm or less are skeletal secondary particles having open pores that are tightly connected to each other, and the average size is 50 to 150 μm, and the skeletal secondary particles of 20 μm or less are 5wt. % or less PbTiO3 powder,
It consists of powders represented by the above ■, ■, or (1), (2), and (3), the main component of which is BaTi. :45-85 mol%,
SrTiO3: 1 to 20 mol%, aTi03
: 5 to 20 mol%, PbTiO3: 1 to 20 mol%
and Y, La,
At least I of rare earth elements such as Ce, Nb, and Sb
II is 0.05 to 0.14 mol% as an oxide, CuO: 0.005 to 0.03 mol%, Mn:
0.005-0.03 mol%, SiO□: 0.5-20
A raw material powder for a barium titanate-based semiconductor ceramic composition characterized by having a composition range of mol %, and a barium titanate-based semiconductor ceramic composition obtained by sintering the above powder, further having a specific resistance value of 10 (Ω cm ) or less, the temperature coefficient of resistance is 9 (
The present invention provides a barium titanate thermistor having a dielectric strength of 50 (V/m) or more and a voltage resistance of 50 (V/m) or more.

The raw material powder of the present invention is obtained by calcining oxalate, and as a result, the unique effects of the present invention are produced.
First, methods for producing these various oxalates will be described.

The important points in these methods are to obtain oxalate as highly pure as possible, and to reduce Ba and Sr in oxalate.
, Pb, Ca and Ti are as close to 1 as possible in molar ratio and there is no variation between crystals. Therefore, in terms of purity, the raw materials such as oxalic acid, titanium tetrachloride, and salts of Ba, Sr, Pb, and Ca must be as pure as possible, and in order to avoid contamination from the reaction container, the reaction container should be made of acid-resistant material such as Teflon. I prefer plastic containers! ! The oxalate finally obtained has a concentration of metal impurities other than alkaline earth metals of several ppm or less.
The total amount is preferably 1100 pp or less. Regarding the molar ratio, it is necessary to obtain particles with uniform crystal shape and particle size and as large as possible, and it has been found that these can be successfully produced by using the following production method.

First, to explain the production of barium titanate, the reaction is carried out by adding a solution of titanium tetrachloride and barium chloride to an aqueous solution of soylic acid. The concentration of barium oxalate titanate tetrahydrate may be set within the range of 10 to 12-t%. Therefore, the water balance between both solutions can be any concentration as long as it is within the set concentration range, but the concentration of barium chloride in the solution should be 10-t to prevent barium chloride from precipitating in a solution of titanium tetrachloride and barium chloride. % or less.

Ba = 'Ti (molar ratio) is 1.02 ~ with slightly more Ba
It is necessary to set 1.054. If Ba,,'Ti (molar ratio) is less than 102, the Ba/Ti (molar ratio) of the main oxalate will be less than 0998, which is undesirable, whereas Ba/Ti (molar ratio) is 1.05. If it is larger, the Ba/T molar ratio of the main oxalate salt does not change significantly around 1.0, but unreacted Ba increases, which is not economical. Shu #/Ti (molar ratio)
From the viewpoint of yield and economic efficiency, the molar ratio of
It is preferable to set the concentration in the range of 10 to 12 wt % from the viewpoint of suppressing precipitation of other salts, economical concentration, crystal shape, etc.

Furthermore, the addition conditions, stirring conditions, and temperature conditions have a major influence on the crystal size, shape, and particle size distribution of the main constituent barium oxalate titanate tetrahydrate, and the addition is 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 stirring at a circumferential speed of at least 2.5 m/sec.

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. At temperatures lower than 55°C, poorly crystalline crystals mainly form, and the Ba/Ti (molar ratio) becomes less than 0.998, while at temperatures higher than 75°C, the crystals formed are unstable. If 6a is easily removed from the crystal and the time until filtration is long, Ba/Ti (molar ratio) is 0.9.
It is not preferable because it becomes lower than 98.

The crystals of barium oxalate ticunate thus precipitated have a Ba/Ti (molar ratio) of 0.998 to 1.05.
Within the range of 4, the inside of the crystal is also 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 7-oxalate. Compared to barium titanate oxalate, Sr/1 (molar ratio) tends to be less than 1, so the Sr used in the preparation,
/Ti (molar ratio) must be set to 12 or more.If the setting Sr/Ti (molar ratio) is smaller than 1.2, the Sr/Ti (molar ratio) of the main oxalate is smaller than 0998. This is not preferable, but it is also uneconomical if it is too large, so it is usually set in the range of 1.2 to 13. The molar ratio of oxalic acid/Ti (molar ratio) is set to 2. The concentration is preferably set in the range of 1 to 2.3%.The concentration is preferably set in the range of 10 to 14 iut% from the viewpoint of suppressing precipitation of other salts, economical concentration, and crystal shape.

Furthermore, the addition conditions, stirring conditions, and temperature conditions have a major influence on the crystal size, shape, and particle size distribution of the main constituent, strontium oxalate titanate pentahydrate, and the addition is 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
If it is not added slowly and in small amounts over a period of time, a similar phenomenon will occur, and the Sr/Ti (molar ratio) of the crystal will be 0.9
It is less than 98, which is not preferable. The stirring conditions are also similar, and although they differ slightly depending on the scale and shape of the container, it is necessary to perform stirring at a peripheral speed of at least 3.0 m/see.

Next, regarding temperature conditions, the crystallization temperature and temperature fluctuations have a large effect on crystallization and are a major cause of precipitation of microcrystals, so compared to barium titanate oxalate, the temperature is 60 to 80°C. It is necessary to maintain a constant temperature in a higher temperature range, and for the same reason as barium oxalate titanate, Sr/Ti (molar ratio)
is less than 0.998, which is not preferable.

The crystals of strontium titanate oxalate 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-t% at the reaction temperature of 60-80°C, so the yield can be increased to 90i% or more by cooling after the reaction. However, since the Sr/T+ (molar 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°Cz'hr.

Furthermore, regarding the manufacturing method of lead titanate oxalate, if titanium tetrachloride is used in this case, lead chloride precipitates will mainly form when the lead salt is dissolved. However, titanium tetrachloride was first neutralized with ammonia to form a gel mainly composed of titanium hydroxide.
After thorough filtration and washing, it becomes a solution by dissolving it in oxalic acid, and this solution can be used. In the case of lead oxalate titanate, the Pb/Ti (molar ratio) varies depending on the conditions, so it is necessary to keep various conditions constant. Considering the ratio, etc., under conditions where the molar ratio is close to 1, Shu#/Ti (molar ratio) is 2.1 to 23, Tj02: 4
It is necessary to keep it below ivt%. Considering the total water balance, it is best to set the concentration of lead oxalate titanate, which is the main component, to 10 to 18%. All you have to do is set the concentration of

Moreover, when the concentration of lead titanate oxalate is set to 10 to 18-t%, 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/Ti (molar ratio) should be 101 to 103.
It is necessary to set Pb/Ti<molar ratio) to 1.0.
If it is lower than 1, the Pb/Ti (molar ratio) of the soylic acid salt is 0.
99 or less, -force setting Pb/Ti (molar ratio) is 1
．． If it is larger than 03, on the other hand, the molar ratio of oxalate becomes 1.01, which is too large. Setting oxalic acid/Ti(
Molar ratio) The same applies even if there are two L. Regarding the liquid temperature during the reaction, it is necessary to carry out the reaction in the range of 45 to 55°C, and anything outside this range is not preferable as the molar ratio becomes lower than 099.

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 noisy state, and the peripheral stirring speed should be at least 2.0 i/sec. It is necessary to do so.

The lead titanate crystals precipitated in this way also
When the Pb/Ti (mole ratio) is within the range of 0.998 to 1002, the inside of the crystal is stoichiometrically uniform, and the crystal grain size is uniform with an average of 50μ■ or more, and there are few small crystals. .

Regarding calcium titanate, which is one of the powder compositions of the present invention, the concentration of Ca/Ti (molar ratio), CaCl2,
By setting the oxalic acid/Ti (molar ratio), the concentration of the main oxalate salt, the temperature of the liquid, the method of addition, the stirring conditions, etc., the crystal grain size can be adjusted so that the Ca/Ti (molar ratio) is close to 1. Similarly, calcium oxalate titanate with a large degree of uniformity can be obtained.

Each oxalate obtained by the above method is in a form in which the protons of the organic acid are replaced by metals or metal oxides, and this is subjected to ordinary sintering in an atmosphere containing sufficient oxygen. By pre-calcining at a temperature slightly lower than the
This forms oxides such as TiO3, PbTiO3, and CaTiO3.

At this time, the crystalline state of the organic matter before decomposition has a great influence on the physical properties such as particle size, particle size distribution, and molar ratio of the oxide after firing.
Furthermore, although the above-mentioned physical properties greatly affect the electrical properties of the most bonded sintered body, the calcined body of the sulfurate obtained in the present invention has uniform and fine particles of about 0.2 μm or less and is lightly sintered. They have a bonding force with each other and have a so-called skeleton particle structure that retains the shape of oxalate before decomposition.Moreover, the particles have a uniform distribution with no uneven atomic distribution. By using a calcined body and obtaining a sintered body through the mixing and firing steps described below, the sintered body itself has a uniform structure, and becomes a porcelain having a low specific resistance, a high temperature coefficient of resistance, and a high withstand voltage.

First, to specifically describe the pre-calcination of barium oxalate titanate, strontium oxalate titanate, and calcium titanate oxalate, 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 keeps the particles at an appropriate size. 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 700-900
°C is preferred; if it is lower than 7.00 °C, oxidative decomposition will not proceed sufficiently and carbon etc. will remain, which is not preferred. 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.

For barium titanate and calcium titanate, the calcined body of oxalate obtained in this way is a skeletal secondary particle having open pores in which primary particles of 0.2 μm or less are connected to each other, and the size of the calcined body is The average particle size is 150 to 250 μm,
The calcined body has a uniform secondary particle size with a BET specific surface area of 6 to 10 rr+/g and 5 wt % or less of skeletal secondary particles of 50 μm or less.

In addition, for calcined strontium titanate bodies, 01μ
A skeletal secondary particle having open pores in which primary particles of less than m are connected to each other, and the average size is 70 to 180 μm,
In this case, the BET specific surface area of the primarily calcined body changes greatly depending on the oxalate production method, and the BET specific surface area of the powder exhibiting excellent characteristics of sintered porcelain is within the range of 20 to 30 rnL'g.

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, and temperatures lower than 600"C are not preferable because the decomposition of carbon dioxide does not proceed and carbon etc. remain. On the other hand, if the temperature is higher than 800"C,
The calcined body of lead oxalate titanate obtained in this way, which is undesirable because uneven grain growth tends to occur and local abnormal grain growth is often observed, also has primary particles of 0.2 am or less. A skeletal secondary particle with mutually tight open pores,
The average size is 50 to 150 μm, the proportion of secondary particles of 20 μm or less is 5 wt% or less, and the BET specific surface area is 6.
It becomes a calcined body having a uniform secondary particle size of ~10r+(7g).

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. In this case, all color sushi is also made from oxalate calcined body. Not necessary, at least BaTiO3, SrTiO
Regarding 3, use a calcined body of oxalate.

In this case, the other PbTiO3 and CaTiO3 may be those produced by the so-called ordinary solid phase method, and usually each raw material powder, for example, in the case of PbTiO3, PbO
PbTiO3&li powder produced by mixing, firing, and pulverizing PbTiO3 and TtO7, and CaTiOa Mi powder produced in the same manner as PbTiOa are used by mixing with the oxalate calcined body.

However, in order to obtain a sintered body with a uniform texture, it is necessary that the powder produced by the solid phase method has a similar average particle size and impurity concentration to the sulfate calcined body, and the average particle size is 2 μm. Below, other metal impurities excluding alkaline earth metals are 1100
It needs to be less than pp.

Next, the composition of the present invention will be explained. The present invention includes BaTiO3, SrTiO3, CaTiO3, and
03PbTi03 is BaTiO3: 45-85 mol%
, SrTiO3: 1 to 20 mol%, CaTiO3
: 5 to 20 mol%, PbTi0a: 1 to 20 mol%
On the other hand, Y, La, and C are used as semiconducting agents.
At least one of rare earth elements such as e, Nb, and Sb is 0.05 to 0.14 mol% as an oxide, and Cu
O: 0.005 to 0.03 mol%, Mn: 0.00
5-003 mol%, 5i02: 0.5-20 mol%
This is a composition in which is added.

BaTiO3-SrTiO3-CaT, the main component of the present invention
The four-component ceramic of i03 and PbTiO3 is obtained by replacing part of Ba in barium titanate with Ca, Sr, and Pb at the same time. When used alone, Pb and Sr shift the Curie point to the high temperature side and low temperature side, respectively, but by containing CaSr and Pb as the main components in a coexisting state and further adding CaSr and 5i02, the withstand voltage value increases. Although it is known that the resistance to high currents and large inrush currents is improved, the composition of the present invention has a very low specific resistance and no other properties have been achieved.

The main component of the present invention is BaTiO3: 45 to 85 mol%
, SrTiO3: 1 to 20 mol%, CaTi
O3: 5-20 mol%, PbTiO3: 1-20
The main components are limited to the above range for the following reasons.

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

If 5rTilI13 is less than 1 mol%, the particles of the sintered body will become coarse, and the effect of improving electrical characteristics will not appear.
If it exceeds 20 mol %, partial grain growth occurs and electrical characteristics 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%,
During firing, PB scatters, making it 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, and Pb and Ti is adjusted within the range of 099 to 1.03, it will hardly affect the physical properties of the manufactured porcelain. We can manufacture things that don't already exist.

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

At least one of sb as an oxide is 0.05~
It may be added or contained in an amount of 0.14 mol%.

If the amount added is less than 0.05 mol%, semiconductor formation will not be successful, and if it is more than 0.14 mol%, the resistivity will increase, which is not preferable. It is preferable to add it in the form of

Furthermore, by simultaneously adding the three components CuO, Mn, and SiO□ to the above composition, the withstand voltage and resistance temperature characteristics can be further improved.

Figure 1 shows that the four main components are BaTiO3: 65
Mol%, SrTiO3: 11 mol%, CaTiO3:
15 mol%, PbTiO3: Additive for 9 mol%, semiconducting agent, components other than SiO3, that is, Mn
This is a diagram comparing the relationship between resistivity, temperature coefficient of resistance, and resistivity and withstand voltage when CuO is added alone, when CuO is added alone, and when Mn and CuD are added at the same time. On the other hand, in the system containing CuO alone, the withstand voltage is lower than other systems, whereas in the system in which Mn and CuO are added simultaneously, both the withstand voltage and resistance temperature coefficient are high, and the so-called synergistic effect is observed. It is acceptable.

In this way, in the present invention, trace amounts of CuO, Mn,
Although the addition of 5102 significantly improves the properties,
Since this also used an oxalate calcined body as the main raw material, the amount added was very uniformly dispersed, and it is thought that the above effects were achieved.

In this case, the amount of CuO added is CuO: 0.005 to 0
．． 0.3 mol %, and these proportions are included in the porcelain.

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

The α value is a parameter that represents the above characteristics.
When CuO is less than 0.005 mol %, the α value becomes small and the breakdown voltage characteristics deteriorate. On the other hand, CuO is 0.03
If it is more than mol%, the α value increases but the withstand voltage decreases, which is not preferable. CuO may be added in the form of oxide, sulfide, or oxalate.

Next, it is preferable that the amount of Mn added is within the range of 0.005 to 003 mol % in the ceramic.

Mn has a remarkable effect of improving the α value and at the same time improving the withstand voltage.If the total amount is less than 0.005 mol%, the withstand voltage characteristics deteriorate, which is not preferable;
If it is more than 0.03 mol %, the withstand voltage will increase, but the specific resistance will become too high, which is not preferable.

Mn may be added in the form of oxalate or oxide.

Next is the addition of 5i02, the amount of which is 5i0
2: preferably in the range of 0.5 to 2.0 mol%.

By adding 5iO7, the change in resistivity caused by slight fluctuations in the addition of semiconductor components is suppressed, and the resistivity value is lowered at room temperature.5i02 is less than 05 mol%. When SiO□ is 2.0
If it is more than mol%, the specific resistance becomes high, which is not preferable.

When adding 5102, it is sufficient to use an oxide with a particle size as small as possible.

As mentioned above, each raw material powder is weighed in 1 cup, and ball mill bots are made of plastic, etc., which are difficult to mix with metal impurities, and balls 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 liquid may be added to increase the disintegration effect. After this step, the liquid is evaporated and
Granulate and mold at a pressure of 0.3 to 1.0 t(/cm'). After molding, raise the temperature at 5 to 10"C/win and heat at 1300 to 1400°C for 5 minutes. After firing for 2 hours, the temperature is raised 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.
Also, if the temperature increase rate is too low, the specific resistance will increase, while if it is too high, the specific resistance will decrease, but the α value will also decrease, which is undesirable. Regarding the firing temperature, if the temperature is too low or too high, the specific resistance will increase. Undesirable.

The porcelain of the present invention produced by the method described above has a density of 5
．． 2 to 5.6 g/C13, specific resistance value is 10 (0 cm)
Below, α value power is 9 (t/”C) or more, II pressure resistance is 50
(V/mm) or more, with low resistance and high withstand voltage, and α
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 element content is extremely high at 1100pp, it does not contain any elements that cause deterioration, and the addition of trace elements makes it easy to control the properties and has a large effect on improving the properties. It has a uniform fine structure consisting of a sintered body with a uniform grain size controlled to an average size of approximately 5 μm, which improves pressure resistance, and the oxalate calcined body, which is the main component, has appropriate strength. Since the bulk particles are a combination of fine and uniform primary particles, the bulk particles are sequentially crushed and mixed during mixing and crushing, resulting in very good mixability, and G during sintering.
It is conceivable that each atom is uniformly dissolved in solid solution, and that when made into porcelain, the distribution of atoms becomes more uniform, and there is no local change in the properties in the porcelain, and the whole shows uniform properties. As a result of 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, we have found that the overall effect is such a remarkable electrical This made it possible to obtain porcelain with special characteristics.

The porcelain thus obtained is extremely useful, particularly as a low-voltage constant-temperature heating element, a current-limiting element, a temperature-controlling element, etc. operated by batteries or batteries.

[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 Capacity is 5n? Ti(O) is placed in rubber-lined tank A.
H) Ti solution 650 containing 27.6 wt% Ti ions in terms of a and 282-t% CI ions in terms of HC1
kg, barium chloride dihydrate 389 kg and pure water 29
80Kg was slowly mixed to form a solution for addition. On the other hand, in rubber-lined tank B with a capacity of 7 d, oxalic acid 4
Dissolve 29 kg in 2055 kg of pure water and lower the temperature to 60 kg.
The temperature was raised to and maintained at that temperature.

At this time, Ba/Ti (molar ratio) -1,03, oxalic acid/
Ti (molar ratio) = 2.2, BaCl2-8.25 i
It was vt%.

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 the form of a shower.

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

Further, the concentration of barium titanate oxalate, which is the main constituent, was set at 11 to t%.

After the addition was completed, the reaction solution was filtered and washed using a centrifuge, and then dried at 50°C to obtain 592 kg of barium titanate oxalate crystals. The yield at this time was 85.
3ivt%, its Ba/Ti <molar ratio) is 0.99
It was 9.

The obtained powder was placed in a porcelain crucible and heated at 900° in air.
Calcination was performed using Cl2hr to obtain calcined powder of norium titanate. The obtained powder contains 10 pP of all metal impurities other than alkaline earth metals! 1 or less, the average particle size was 200 μm, and particles with a diameter of 50 μm or less accounted for about 2 wt%. The above particle size distribution was measured using a laser particle size distribution analyzer (PRO-7000) manufactured by Seishin Enterprises.

Example 2 Ti(
OH) 31.9 wt% Ti ions in terms of a, 1(C
Ti containing 31.9 iut% C] ions in terms of I
Solution 449 Kg, Strontium chloride hexahydrate 516K
g and 1590 kg of pure water were slowly mixed to prepare a solution for addition. On the other hand, the capacity is 7n? Rubber lined tank B
Next, #429 kg was dissolved in 2147 kg of pure water, and the temperature was raised to 75°C and maintained at that temperature.

At this time, Sr/Ti (molar ratio) = 1.25, oxalic acid/Ti (molar ratio) = 2.2.5rC1212.0wt%
Met.

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 stirring circumferential speed at this time was 4.1 sec/sec.

The solution during the reaction was maintained at 75°C and the addition time was 2.5 hours. Further, the concentration of strontium titanate oxalate, which is the main constituent, was set at 12 igt%.

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 oxalate pentahydrate were obtained. The Sr/Ti (molar ratio) of this sulfate salt was 0.999, and the yield was 9
It was 3-t%.

The obtained powder was placed in a porcelain crucible and heated at 900° in air.
Calcined powder of strontium titanate was obtained by firing with Cl2hr. The obtained powder contained metal impurities other than alkaline earth metals of 10 pp or less, an average particle diameter of secondary particles of 150 μm, 25 t% of secondary particles of 50 μm or less,
The BET specific surface area was 26 Om2/'g.

The BET specific surface area was measured using a flow type automatic specific surface area measuring device Micromeritinox Flowsonop II Model 2300 manufactured by Shimadzu Corporation.

Example 3 TiC11: A 10 wt% solution was cooled to below 40°C and neutralized with an ammonium aqueous solution until the pH reached 7 to obtain gel-like titanium hydroxide, which was then filtered and purified with pure water. Wash. The gel after washing was immediately dissolved with oxalic acid, and after measuring the concentration of Ti ions, the concentration of Ti ions was 2.4 gt% with pure water and oxalic acid.
Oxalic acid/Ti (molar ratio) was adjusted to 2.15, and 2378 kg of this solution was transferred as an addition solution to a rubber-lined tank A having a capacity of 7 rrr. On the other hand, 402 kg of lead nitrate and 1086 kg of pure water were put into a rubber-lined tank B having a volume f of 5- to form a solution. Pb/T i at this time
(Molar ratio)=1.02, and the set concentration of lead oxalate titanate as the main constituent: 16.0iit%.

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 pipe and adding the solution to the liquid surface in the form of a shower.

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 w/see.

The solution during the reaction was maintained at 50°C and the addition time was 20 hours.

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 97.0
wt%, Pb/Ti (molar ratio) of lead oxalate titanate was 0.998.

The obtained powder was placed in a porcelain crucible and heated at 700° in air.
A calcined powder of lead titanate was obtained by calcining with Cl2hr. The obtained powder contains all metal impurities other than alkaline earth metals at 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 11 Main component raw materials include BaTi0a-SrTiO3,
For CaTiO3, the oxalate calcined powder produced in Examples 1 to 3 was used, and as CaTiO3, CaCO3 and T
Manufactured from iO2 by solid phase method, all metal impurities other than alkaline earth metals are 10 pp@ or less, average particle size is 0.5
Powder of μm was used.

Next, lanthanum oxide was used as a semiconducting agent, and copper oxide, manganese oxalate, and silicic anhydride were used as other trace components. Particles having the following particle sizes were used. These raw materials were mixed in a composition ratio as shown in Table 1, a binder was added, a 501 polyethylene ball mill pot and a zirconia ball were used, ethanol was added, and the mixture was heated for 24 hours. Equation mixing was performed.

After dehydrating and drying this and granulating it, the molding pressure was 1000 kg/
It was molded into a disk shape using ci. Furthermore, Examples 4 to 7
The samples were baked at 1320°C for 30 minutes, and Examples 8 to 11 were baked at 1340°C for 130 minutes. A disc-shaped sintered body having a thickness of 100 ml 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. The specific resistance value, α value, and withstand voltage value were measured for these samples. The relationship between these resistances and temperature is pA meter: Yokogawa Hule 2 Tobano Card ■
Using Model 4140B, X-Y recorder; Model 3086 manufactured by Yokogawa Hokutatsu Electric, the sample was placed in a constant temperature bath, and measurements were taken while raising the temperature at a constant rate.

The Curie point of Example 4 was 94°C.

In addition, 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.

Table 1 shows the sample composition and measurement results of electrical properties. Second
The figure shows the resistance-temperature characteristics of the porcelain obtained in Example 4, which can maintain a low resistivity and a high α value.

Comparative Examples 1 to 9 In each method of Examples 1 to 3, each oxalate was produced by changing only one condition, calcined in the same manner, and the calcined powder was used. , Example 4
Porcelain was manufactured using exactly the same composition and method, and its electrical properties were measured.

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

According to the above comparative example, as shown in Table 2, powder containing powder with a small average particle size and secondary particles with a small diameter is the main constituent, and when porcelain is manufactured using the powder, It can be seen that the electrical properties such as specific resistance and withstand voltage are inferior to those of the examples.

[Effect of the invention] The raw material powder, which is the main component of the present invention, is a secondary particle with a unique shape consisting of fine primary particles with a uniform particle size, and a semiconducting agent, CuOlMn, and SiO□ are added to this raw material The barium titanate-based semiconductor ceramic composition obtained by sintering the mixed powder composition has a specific resistance value of 10 (Ω cm ) or less, an α value of 9 (Z/'C) or more, It has a low resistance of 50 (V/'ml) or more, and has excellent electrical characteristics such as voltage resistance and α value, so it is especially suitable for current limiting devices and temperature control devices for low voltages using batteries, pantry batteries, etc. as power sources. It can be applied to various uses such as an element, a constant temperature heating element, etc.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between resistivity, temperature coefficient of resistance, and withstand voltage of the semiconductor ceramic composition of the present invention, and FIG.
FIG. 2 is a resistance temperature characteristic diagram of a barium titanate-based semiconductor ceramic composition of the present invention. Patent applicant Central Glass Co., Ltd. (Ω・cm)

Claims (1)

[Claims] (1) BaTiO_3, SrTiO_3, CaTiO_
3. Among the main components of PbTiO_3, at least BaTi
O_3, SrTiO_3 is (1) BaTiO_3:0
．． A skeleton secondary particle with open pores in which primary particles of 2 μm or less are connected to each other, and the average particle size is 150 to 250 μm.
m, and 5wt% of skeletal secondary particles of 50 μm or less
BaTiO_3 powder, (2) SrTiO_3
: Formative secondary particles that have open pores in which primary particles of 0.1 μm or less are connected to each other and have an average particle size of 70 to 180.
μm, and its BET specific surface area is 20 to 30 m^
2/g SrTiO_3 powder, (1) and (2) above
The main component is BaT.
iO_3: 45-85 mol%, SrTiO_3: 1-2
0 mol%, CaTiO_3: 5-20 mol%, PbTi
O_3: 1 to 20 mol%, and 0.05 to 0.14 mol% of at least one of rare earth elements such as Y, La, Ce, Nb, and Sb as a semiconductor agent as an oxide based on the main component. , and further CuO:
0.005-0.03 mol%, Mn: 0.005-0.
A raw material powder for a Chitavari-based semiconductor ceramic composition, characterized by having a composition range of 0.03 mol% and SiO_2: 0.5 to 2.0 mol%. (2) BaTiO_3, SrTiO_3, CaTiO_
3. Among the main components of PbTiO_3, at least BaTiO
_3, SrTiO_3, and PbTiO_3 are: (1) BaTiO_3: Primary particles of 0.2 μm or less are connected to each other to form secondary particles having open pores with an average particle size of 150 to 250 μm and 50 μm or less. BaTiO_3 powder with 5 wt% or less of skeletal secondary particles; (2) SrTiO_3: skeletal secondary particles having open pores in which primary particles of 0.1 μm or less are connected to each other, with an average particle size of 70 to 180 μm. Yes, and the BET
SrTiO_3 with a specific surface area of 20 to 30 m^2/g
Powder, (3) PbTiO_3: skeletal secondary particles having open pores in which primary particles of 0.2 μm or less are connected to each other, the average size of which is 50 to 150 μm, and 5wt of skeletal secondary particles of 20 μm or less % or less of PbTiO_3
Powder, consisting of powders represented by (1), (2), and (3) above, whose main component composition is BaTiO_3:45-8
5 mol%, SrTiO_3: 1-20 mol%, CaTi
O_3: 5 to 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 an oxide to the main components as a semiconductor agent. .05 to 0.14 mol%, further CuO:
0.005-0.03 mol%, Mn: 0.005-0.
A raw material powder for a Chitavari-based semiconductor ceramic composition, characterized by having a composition range of 0.03 mol% and SiO_2: 0.5 to 2.0 mol%. (3) BaTiO_3, SrTiO_3, CaTiO_
3. Among the main components of PbTiO_3, at least BaTi
O_3, SrTiO_3 is (1) BaTiO_3:0
．． A skeleton secondary particle with open pores in which primary particles of 2 μm or less are connected to each other, and the average particle size is 150 to 250 μm.
m, and 5wt% of skeletal secondary particles of 50 μm or less
BaTiO_3 powder, (2) SrTiO_3
: Formative secondary particles that have open pores in which primary particles of 0.1 μm or less are connected to each other and have an average particle size of 70 to 180.
μm, and its BET specific surface area is 20 to 30 m^
2/g SrTiO_3 powder, (1) and (2) above
The powder represented by is used as raw material, and its main component composition is Ba
TiO_3: 45-85 mol%, SrTiO_3: 1-
20 mol%, CaTiO_3: 5-20 mol%, PbT
iO_3: 1 to 20 mol%, and 0.05 to 0.14 mol% of at least one of rare earth elements such as Y, La, Ce, Nb, and Sb as a semiconductor agent as an oxide based on the main component. , and further CuO:
0.005-0.03 mol%, Mn: 0.005-0.
1. A Chitavari-based semiconductor ceramic composition characterized by having a composition range of 0.03 mol% and SiO_2: 0.5 to 2.0 mol%. (4) BaTiO_3, SrTiO_3, CaTiO_
3. Among the main components of PbTiO_3, at least BaTiO
_3, SrTiO_3, and PbTiO_3 are: (1) BaTiO_3: Primary particles of 0.2 μm or less are connected to each other to form secondary particles having open pores with an average particle size of 150 to 250 μm and 50 μm or less. BaTiO_3 powder with 5 wt% or less of skeletal secondary particles; (2) SrTiO_3: skeletal secondary particles having open pores in which primary particles of 0.1 μm or less are connected to each other, with an average particle size of 70 to 180 μm. Yes, and the BET
SrTiO_3 powder with a specific surface area of 20 to 30 d/g, (3) PbTiO_3: A skeletal 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 50 to 150 μm. , and PbTiO_3 powder containing 5 wt% or less of skeletal secondary particles of 20 μm or less, using powders represented by (1), (2), and (3) above as raw materials, and having a main component composition of BaTiO_3:45-85.
Mol%, SrTiO_3: 1-20 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, Nb, and Sb is added as an oxide to the main component as a semiconductor agent. .05 to 0.14 mol%, further CuO:
0.005-0.03 mol%, Mn: 0.005-0.
1. A Chitavari-based semiconductor ceramic composition characterized by having a composition range of 0.03 mol% and SiO_2: 0.5 to 2.0 mol%. (5) Comprised of the semiconductor ceramic composition according to claim (3) or (4), which has a specific resistance value of 10 (Ω·cm) or less, a resistance temperature coefficient of 9 (%/°C) or more, and a withstand voltage of 50 (Ω·cm) or less. V/mm)
A Chitabari thermistor characterized by the above characteristics.