JPS62235214A - Production of semiconductive srtio3 particle and high-dielectric constant ceramic - Google Patents

Abstract

PURPOSE:To obtain the titled semiconductor particles having small particle diameter and desirable for a high-capacity laminated capacitor by mixing Sr, Ti, and the compd. of a doping metal, baking the coat particles formed by a sol-gel technique, and baking the formed powder. CONSTITUTION:SrTiO3 powder is impregnated or mixed with the sol-gel soln. of the alkoxide of a doping metal in the protective atmosphere of pure nitrogen or Ar or mixed with the soln. Ethanol, propanol, etc., are appropriately used as the solvent in this case, the concn. of the metallic compd. in the soln. is controlled to about 5-20%, and the soln. contains a small amt. of water and a catalyst such as HCl. The formed gel layer is then dried, and heated to transfer the deposited metal into the oxide. The SrTiO3 powder which is not doped is dipped in the soln. of the alkoxide in an org. solvent, drained, then dried, heated in the air,and burned and reduced. The reduced substance is crushed and then pulverized by a ball mill into ca. 0.5-5mum particle diameter, and the desired semiconductive SrTiO3 particles are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention provides a semiconducting S
The present invention relates to a method for producing rTiO3 particles and a method for producing high dielectric constant ceramics using the particles.

``Prior art'' In a multilayer capacitor, pairs of positive and negative electrodes are stacked in series, one electrode and the other electrode are connected at both ends, and the sum of the areas of each pair, that is, the sum of the components, is This is a method of increasing the capacitance and decreasing the physical size since it is made to be the effective surface of the capacitor.

The use of grain boundary barrier layer ceramics in the manufacture of small, high capacity capacitors has been known for some time. As early as,
In 19130, British Application No. 849938 disclosed the sintering of high purity BaTi03 at 1450° C. in hydrogen gas to produce porous, semiconducting BaTi03 with an average particle size of 1 t. This substance is then released into the atmosphere at 650-10
Oxidized at 0.000 C to result in an insulating oxidized internal grain boundary barrier layer approximately Ions thick. The characteristics of a capacitor formed from such a dielectric ceramic are the effective permittivity k (or ε
) is about 100000, loss tan δ is 5 KHz,
It is about 0.03 (Q=about 30) at 5 Vrms.

Due to their excessive porosity, thermal instability, and low operating voltage, these materials have been essentially abandoned in technology and replaced with semiconducting materials doped with transition metals such as lanthanum, niobium, and tungsten. Strontium titanate has been used and sintered as is or mixed with liquid phase barrier grain boundary materials such as zirconia, bismuth tungstate, lead germanate and others (see, for example, Japanese Application No. 52-10598). In the case of sintering without a liquid phase, when doped SrTiO1 slabs were coated with metal oxides and then fired in an oxidizing atmosphere, grain boundary materials were generated by diffusion from the surface (see Japanese Application No. 50-27996).

discloses a method for preparing SrTiOz, N
A slurry consisting of b2O5 and GeO2 and an organic binder is formed into a disk, and heated to 1350°C in an atmosphere containing hydrogen.
It is fired at ~1480°C. The insulating grain boundary layer is Bi2O
3 on the disk surface and firing at 1300°C, which causes diffusion of molten oxide into the ceramic. Dielectric constant 3~5X
104. A coefficient Q of approximately 100 was obtained.

Japanese application No. 51-848 discloses SrTiO3, Nb2O5 and C.

The grain boundary layer of 5i02, B
203, GeO2, P205. Al2O3, MgO1
Obtained by liquid diffusion at 1100° C. using glass oxides selected from ZnO1Bi203 and TiO2.

Japanese application No. 58-97820 describes SrTiO3, WO
A semiconductive ceramic is made by pressurizing a mixture of x, Ge20, Al2O3 and 5i02 and sintering it at 1350-1450°C in a 1/99 hydrogen/nitrogen atmosphere. I, f chair-Pj'1
．． fzsg, PbO, I'l 90t and Bi20z
The mixture is melted and diffused into the ceramic at 1150-1300°C to form a single insulating layer. Dielectric constant (
ε) about 100,000 and a Q coefficient of 2QO is preferable when the Si/A1203 ratio is about 1.5 to 5.
．． Obtained at 0. The average particle size is 60-120gm,
The resistivity of the grain boundary layer was approximately 2×10 9 Ω·C11.

Japanese application 52-10598 is Nb205, Ta20
], doped SrTiO3 mixed with oxides such as WO3 or TiO2 and calcined at about 1400° C. in a reducing atmosphere. If the dope is about 1% by weight, a resistivity of better than 10 Ω·cm is obtained. This application discloses the use of SiO2 as a sintering additive to grow particles with a particle size of approximately 10 tons for application in multilayer (BL) capacitors. This application also applies to Zr.
It is taught that the Q factor and resistivity can be improved by adding O2 to SrTiOx and sintering it. The boundary layer is
It is obtained by liquid diffusion of a mixture of PbO, B203 and Bi20).

Typical properties are Q'>200 at t = 30,000.

When preparing the high dielectric constant ceramic described above, the niobium-doped particles used as the inner particle layer are produced by doping SrTiO3 with a doped metal composition, mixing with e.g. niobium oxide and then firing the mixture. .

Note that the firing is performed at, for example, 1450 to 1500°C, H2/N
It is a reducing atmosphere like 2. Further, in this case, a mixture of strontium carbonate, TiO2, and Nb2O5 may be fired.

This technique is generally suitable for forming particles of substantial size (about 10 gm or more) suitable for making BL capacitors. However, it is not very suitable for producing particles of a size suitable for multilayer capacitors, that is, 10 m or less, or even smaller.

In fact, the effective dielectric: J (or effective insulation constant) of a barrier layer ceramic with an insulating layer at the grain boundaries of the semiconductor grains corresponds to the grain size and the thickness of the insulating layer. This relationship is, for example, Ti
Ultra-high di'rL capacitance of O2 ceramic: M
, F., YAN and W., W., RHO.
DES.

Be1l Laboratories, Murra7
Hill, N.J., 0794;Adv.
, Gera, (1983), Additio
n, Interfaces Electr, Cer
ata, (7), 22B-238.

C= Kgbφ D/d X S/e where S and e
are the area and thickness (cm) of the sintered disk, respectively, and D, Kgb, and d are the grain size, the true dielectric constant of the grain boundary insulating layer (barrier layer), and the thickness of the grain boundary insulating layer, respectively. In this way, 10 to 50 gm in particle size,
Grain boundary layer 102-10' nm.

(0.1 to 1 m), with an effective dielectric constant of 104 to 10
5 was obtained.

However, when the particle size becomes about 5 to 10 layers, this dielectric material becomes
Not suitable for multilayer capacitors. Its particle size is 30p
-m is good as a dielectric, and efforts have therefore been made to concomitantly reduce the grain size and barrier layer thickness. Liquid phase obtained by sintering lead germanium and borate (see: Cbaratrization ofIntern
al Boundary 1 ayer Capact
ons: by H, D, PARK and D, A
, PAYNE, Advance Sin Ceram
ics.

Vol, 1 page 242-253.1982), particle size 0.5-2, m, barrier layer thickness 100 mm (0,
1#Lm) and tan δ is about 1O-2), with small temperature dependence (5-1oz) (reference US Pat. No. 4,158,219).
, U.S. Pat. No. 4,237,084). tanδ is the loss coefficient, δ
is the phase angle θ and 90° when alternating current flows through the capacitor
Ideally, θ should be π/2 and δ should be O so that there is no output loss in the capacitor. Q is tanδ
For example, Q=17tan δ.

``Problems to be Solved by the Invention'' Conventionally, in order to increase the dielectric constant and reduce the loss of multilayer capacitors, various studies have been conducted on semiconductor particles as ceramic materials, particle diameters, and barrier layer thicknesses. It is considered desirable that the diameter be small. However, conventional manufacturing methods have not been able to produce semiconductor particles small enough to produce multilayer capacitors with high dielectric constant and low loss.

``Means for Solving the Problems'' An improvement over the prior art is desired and a doping technique has been invented to obtain small homogeneous dope particles without elaborate and complicated grinding processes. The method described in claim (1) of the present invention, in which a high dielectric constant ceramic can be obtained without sacrificing the dielectric constant nδ), is a first step forward.

Thus, the technique used to prepare metal-doped SrTiO3 according to the definition of the invention is to impregnate or mix SrTiO3 powder into a sol-gel solution of the doped metal alkoxide, for example in a protective atmosphere (eg pure nitrogen or argon). Solvents such as ethanol, propatool, butanol acetylacetone are suitable, and the concentration of metal compound in solution is about 5-20%. However, this limit is not strict and can be exceeded. The solution usually contains a small amount of water and a gelled catalyst, such as HCI or other acids (or N
The gel-like layer is then dried and heated to transfer into the precipitated metal oxide.

Appropriate heat treatment is in air at 400-1000℃ for 1~
It is 2 hours. In this way, undoped SrTi
The O3 powder was immersed in a niobium alkoxide organic solvent solution, drained and dried at 90°C, and heated at a low heating rate (4°C/s).
(appropriately) to 600°C in the air. Then, it is reduced by combustion. For example, 1450 to 1 in a reducing atmosphere for 2 hours.
This reducing atmosphere heated at 500°C is, for example, 1 to I
OX H2-Ar or H2-N2 blanket'y-y) or CO/CO2 (V/V) blankets are used. In order to obtain a dope powder of suitable particle size, the reducing material is then crushed and ground in a ball mill to the desired particle size, e.g. 0.5-5 lm.

In some cases, the above sol-gel doping process was applied to TiO2 and niobium, the doped and reduced TiO2 was then mixed with strontium carbonate, and the mixture was then reduced at 1300-1500 °C under similar conditions. , grind to appropriate particle size.

Furthermore, Ti and Nb alkoxide in the solution are reacted with ammonia to form a gel, and the gel is separated and dried.
A pure powder of doped TiO2 is prepared. In addition, the above T
The iO2 is later mixed with SrcOz and reduced by firing in an atmosphere containing hydrogen or co.

This example requires gentle treatment conditions to prevent continuous growth of particles during treatment, but the difference in this example is that a gel solution of Ti and Nb alkoxide is sprayed using a spray pistol. ), ammonia solution with rapidly stirred spray particles (1 to 10 wt% NH4OH in water)
), thereby making the very small particles almost gel-like. Small particles are separated from the solution by filtration or otherwise and gradually raised to temperature (1-b) in air. After cooling, the dried particles are injected with strontium (S).
The desired amount of rCOz form B) is mixed and the mixture is heated slowly again in air to 1000° C., without substantially exceeding this temperature. This thermal pretreatment in air results in a substantial reduction in the temperature required at the final reduction state. To be effective, the reduction must then be
This is done by heating in a reducing atmosphere at a temperature not exceeding 1000°C. Note that this reducing atmosphere has a ratio of hydrogen or carbon monoxide to nitrogen, carbon dioxide, argon, helium, or usually H2 to other gases of 1/99 to 10/90.
It is. Continuing the process at a somewhat lower temperature than in the previous example can reduce particle growth and reduce particle agglomeration during the grinding process to reduce the material to fine particles. 20 hours can be reduced to about 1-2 hours or even less, with a desirable average particle size of 1 g.
m or less.

That is, the proportion of grains larger or smaller than the average grain size is much reduced, and this condition improves uniformity and reproducibility in the practical manufacture of high dielectric constant ceramics.

The sol-gel metal doped strontium titanate obtained by the process of the present invention is advantageous for use in making high dielectric constant insulating ceramics by sintering. Even if pressure molding is done properly, sintering or sintering may be necessary to reduce grain size during sintering or ultimately (in whole or in part) to produce the desired internal grain boundary layer material. It is desirable to use a cohesive agent.
This is particularly desirable when forming a multilayer capacitor that requires V l ÷ + num or less, preferably within that range.

The liquid phase of the sintering aid is selected from metal oxides commonly used in making capacitors with internal grain boundary layers. The sintering aid is added in powder form and mechanically mixed with the doped SrTiO3. They are also added using sol-gel technology, which is new when making a major invention.

The main advantage of this is that by keeping the particles of conductive (or semi-conducting) powder in contact with the solution of the metal compound, the barrier layer thickness is Improved control of the

That is, the amount of the coating material deposited in the //I state can be changed by adjusting the processing conditions depending on the change that occurs in the electrical properties of the ceramic finally obtained. In this way, the effective thickness of the internal grain boundary barrier layer in this layer is as small as 0.8-1.5 n+s4 m, and of course the contact time of the dipping operation (
Also, of course, the number of times the dipping process is repeated), temperature, solution parameters (5 degrees, solvent, PH on gel ratio, etc.)
By changing the thickness, it can be made thicker. This effective thickness was calculated by comparing I7 the optically measured coating (later dried) with a glass plate treated under the same water immersion conditions. Generally, advantageous results indicate that the inventive method provides conductive particles with a dry weight gain of 10-' to 10-2 (e.g. 10-2
Another advantage of the present invention is that the sintering temperature can be lowered to continuously reduce grain growth effects during sintering.

Generally, the impregnation of 5rTix (7) doped powder is performed using SrT
It is carried out in a manner similar to the technique used to dope iO3 particles. That is, by mixing the powder (approximately 0.8 to 5 microns particle size) in a protective atmosphere (e.g., nitrogen, argon) with an organic solution of the material to be deposited as a layer. Solvents such as ethanol, propatool, butanol, acetylacetone, etc. are suitable, the proportion of metal material in the solution is about 5-20%, these conditions are not strict and may be exceeded, generally the solution This acid contains a small amount of water and a gelling catalyst, such as HCI or other # (or even a base like NH4OH).
A gel layer is added to the surface of the particles, which gel layer is substantially dried and heated to convert the gel into an oxide of the insulating or precipitated metal material. Make R richer,
A suitable heat treatment to fully oxidize the remaining pacifier material is heating at 500-600° C. in air for 1-2 hours.

There are many metallic materials suitable for making alkoxide solutions, including those commonly used in the technology for producing sintering aids, for example lead hequinates and germanium alkoxides, or boron alkoxides, bismuth alkoxides, or silicon. Solutions containing alkoxides and aluminum alkoxides are used. Impregnation with said solvent results, after said drying, in each layer of lead germanate, lead bismuth borate, aluminum silicate, respectively. Combining multilayers is sometimes advantageous, e.g. one or multiple layers of aluminum silicate. is supplemented by one or more layers of germanium 1% i lead. The interesting column layer significantly impedes particle growth during sintering. This is totally beneficial and
It is unimaginable from the perspective of the prior art to report an adverse effect.

When accomplishing the sintering step of the present method, it is sometimes desirable to supplement the liquid phase produced by the techniques described above with a powdered sintering aid. To do this, the coated SrTiO:l is mixed with the addition of a dry powdered sintering aid, and this mixture is then mixed with a cracked binder (a volatile or combustible polymer such as polyvinyl alcohol or polyvinyl butyl). ) and pressure mold. Powdered compounds added and used as liquid phase sintering aids include, for example, PbO, GeO2, Bi
20x, H3BO3, P205, 5rTiQ1
Choose from. The use of SrTiO3 as a liquid phase sintering component in the sintering of semiconducting doped SrTiO3 is novel and represents an important improvement in internal grain boundary phase stability, dielectric constant and Q-factor. The following components of the sintering aid are proposed (by weight):

Pb078$ -GeOz 222 (PGO);
Pb0451 B203 20%-Biz 03 2
0%-GeO25%-Ba010SP20520% (
When using ZPhBa), SrTiO3 as a sintering aid, it is preferably added in a weight proportion of 5 to 15% to one of the above proposed compositions.

The sintering conditions for converting semiconducting SrTiO3 particles mixed with a liquid phase obtained by sol-gel or otherwise into a high dielectric constant internal grain boundary layer ceramic are as follows: First, a binder is added to the particles and pressure is applied to form a compact (disk or plate). and then sintering at a commonly used temperature of 1000 to 1300° C. in an inert gas atmosphere such as nitrogen or a rare gas, or in a weakly reducing atmosphere such as a mixed gas of N2 and N2. A high dielectric constant of 10 G is therefore obtained, but the Q-factor is low; subsequent heat treatments such as air annealing increase the Q-factor and the mechanical strength of the disk at the expense of some dielectric constant.

Generally, the coated powder is mixed with 1-3z polyvinyl butyral binder (approximately 1-2g powder), and piston pressurized (
2 to 5 tons/C11”) and approximately 10 to 20 m in diameter
A disk with a thickness of 1 to 3 mm was used, and an electrode was provided on the disk to measure the electrical characteristics (capacitance, loss factor, and Q factor were measured using the usual method).
10@2F ) = 0.0885 S e /e, while calculating ε or K (permittivity), S is squared cv
, e icm. The electrodes are either sputtered with Cu, Ag, Pt, or Au using a regular sputtering device, or screen-printed with silver as a paint or paste that is cured at 150°C or fired with the molded body. It is.

The electrical properties of sintered ceramics can be improved by diffusion, a post-treatment similar to that shown in the prior art, e.g.
A mixture of various glasses forming a binder and a slurry of oxides is applied to both sides of the ceramic disc.
900-1000 to melt and diffuse to become ceramic
In some cases, the liquid diffuser is combined with electrode formation; i.e., the glass-supplied oxide compound is made into a paste with a silver paint compound, and this paste is applied to the ceramic and then heated for diffusion. Heat.

During diffusion, the grain boundary barrier insulating material penetrates the ceramic,
Silver is deposited on the surface and becomes the desired electrode.

The compositions selected to achieve the above results are listed below in weight percent.

Similar diffusion was otherwise achieved by utilizing vapors of selected molten oxides. In this case, the oxide is melted in a crucible (PT) and the disk is placed at the entrance of the crucible with a suitable wire hook at the top of the melt (approximately
3 cm). Good compositions for this method are the above-mentioned composition (h) melted at 800°C and the composition (BP) of 40/80 B 20 z/PbO melted at 900°C.

The following examples provide a detailed explanation of the invention.

"Example 1" Niobium ethoxide solution (S2) was composed of 10 g of acetylacetone; 4.78 g of niobium ethoxide and 24.02 g of n-butanol. and 1.2 g of HCI (0, IN ethanol solution).

Approximately 15 g of pure strontium titanate powder was soaked in the above solution for 5-B minutes at room temperature. Then drain it 2
The mixture was heated at 800° C. (heating rate 2° C./min) for an hour. This operation was repeated once more, and after sowing, the powder was heated at 1480°C for 2 hours at 10% Hz/Ar (heating rate 7
℃/win). The semiconductive powder (STK-1) thus obtained was mixed with a 9 mm wc/co pole and a 3:1 mixture of petroleum ether and tert-butanol as a grinding liquid.
The mixture was used to grind in a plastic mill. After grinding, the powder was drained and dried. Its resistivity was measured by standard means and found to be 1.49 ohm.

The coating of the powder particles consisted of 12 g of 7cetylacetone, 1.08 g of Ge(OEt) 4 , 2.74 g of p
b(n)-2-Ethylhexane was prepared by soaking it in a solution containing 23.32 g of n-butanol and 0.98 g of HGI (0,IN ethanol solution PG2). After thorough impregnation, the powder was drained and dried in the air for 2 hours at 55°C.
Heated to 0°C (heating rate 5-7°C/win) L/t. This coating operation was repeated twice for sample C4W and four times for sample C4L-V.

The powder was then pressed into a disk (15 mm diameter, 1 inch thick) as described above at 2.57 cm, and the disk was sintered as shown in Table 1. The characteristics were shown.

“Example 1aJ Semiconducting strontium titanate powder (STKI) was prepared as in Example 1 but doped (dopa).
nt), 5 g of acetylacetone, 2.39 g of niobium ethoxide, 12.18 g of ethanol and H
A solution containing 0.8 g of C:+ (0, IN ethanol solution) was used. Infiltration was as in Example 1 and reduction was at 1483°C in 10% H2/Ar10X. The resistance of the powder was substantially the same as that of the STK-1 powder described above.

The grain boundary barrier layer consists of doped SrTiO3 powder and 1
9.9LP, P, W pbo and 5.49P, P, W)
It was produced in the same manner as before by pulverizing it with powder CPGO mixed with GeO2. In this case, P.G.O.
The weight of the powder was 5z relative to SrTiO3. The oxide was melted in air at 900°C, the glass was then broken into pieces, and the resulting powder was ground in a plastic ball mill using WC pole and a 3:1 ratio of petroleum ether and t-butanol as described above. and the particle size is about 0.5~2
It was set as pm. Sintering into test disks was carried out as shown in Table 1, and the electrical properties were compared and shown in Table 1.
7 in Table 1! "Flat" means that the heating temperature was suddenly raised.

し J->l N2 l'/
112101 1201 72161
2.4 This result shows that the electrical properties (ε and Q) of the sol-gel coated sample are better than those with a specified mixture of liquid phases, and the sample with three layers of boundary layer forming material This shows that it is better than the one with 5M.

"Example 2" The first solution (A) contains 28.55 Ti(0Et)4
g and 100 g of alcohol and Wb (0 Et) 5 to 0.
56g and then adding alcohol at room temperature until 8281'? I prepared it. Added to this was solution (B), which was 13.51 g of 0
．． Contain 5N NH40H aqueous solution and alcohol until it reaches 6261.

The mixture resulting from the addition of B to A is 0.1 M titanium and 0.59 M water, which also contains 0.054 mol NH4OH, from which a precipitate is formed, stirred for 1 hour, and 830+sl Add water and stir continuously for 15 minutes. After it was left to stand for 16 hours, the liquid that floated to the top was siphoned off, taken out, and dispersed in 1 liter of alcohol by refluxing for 1 hour.

The particles were then filtered again and dried at 80°C overnight. The dry mass is made into a clean powder, and the powder is blown into the air for 5 minutes.
It was heated at 50°C (1°C/win) and kept there for 1 hour.

Nb-doped TiO2 (8.83g) was mixed with SrCO1 (1
5,59g) and heated at 1300°C for 3 hours in air.
Heated.

As a result, strontium titanate contains niobium by 0.7
It contained 2 moles. It is then reduced to a semiconductor, which is conventionally heated at 1480°C for 4 hours in 10Z H2/
It was heated in an Ar atmosphere. Finally, the powder was milled in a plastic ball mill using 50 tungsten carbide balls as catalyst in 3:1 as described in other examples.
Triturated using petroleum ether/l butanol organic layer. After drying in air at 90°C for 4 hours, the powder was finally (
4° C./5 in) and held at 550° C. in air for 1 hour. Its resistance was almost the same as the corresponding powder I of Example 1.

This was then carried out using the solution described in Reference Example 3) for producing an insulating grain boundary barrier phase. Four successive layers were applied by drying at 90°C for 4 hours, followed by 5
A coated powder (V) was obtained by heating at 50°C for 1 hour in air (4°C/IQin heating rate).

This powder was pressed into a disk as described above, the compact was sintered under the conditions shown in Table 1, electrodes were provided as usual, and the electrical properties were measured as in other examples. Indicated.

Table ■ *Sample V-B was first heated at 1200°C for 100 minutes and then heated at 1350°C for 1 hour.

The ceramics of Examples 1 to 5 are suitable for making small-sized, high-capacity multilayer capacitors.

Optionally, niobium-doped semiconducting SrTiO3 powder is obtained as follows. That is, initially TiO2
doped with niobium alkoxide solution,
Further, it is obtained by processing as in the case of sol-gel doping of SrTiO3 (Reference Example 1). Then, the TiO2 treated niobium is mixed with an appropriate amount of strontium salt 1 usually SrCO3, and the mixture is
Reduction was carried out at 300-1500''C in a large amount of hydrogen atmosphere.

"Example 3" Strontium carbonate (923.78 g, 6.26 mol)
and TiO2 (500 g, 8.28 mol) in nitrogen at 1
4g of Nb(OEt) s (0,044% Le) (
7) 240g of solution and 100g of noacetylacetone solution
of n-butanol and 4 mg of H(:I (added as a 0,IN ethanol solution) for 3 hours.
The slurry was kept at room temperature, drained and separated from the liquid, and then ground in a zirconia mill with 1 kg ZrO2 poles. The grinding liquid is water. The crushed mass was dried in the air and then heated in the air in an aluminum crucible at 1100°C for 2 hours (heating rate 400"C/
hr), 'a compound for a certain period of time (2 to 4 hours) 14
50~1480”0 tet.

Heated and reduced under /90H2/N2 gas flow, the rate of temperature rise was about 300-420C/hr. The reduced product was then milled in a polyethylene mill with wc/co pole to 0.5-5 ILm. The grinding liquid was a mixture of 75/25 petroleum ether/l.butanol.

The doped, ground strontium titanate was washed with acetone and contacted with the selected sol-gel solution for 30 minutes in a glove box.

HM9SIA and PGI were used as the two solutions.

HM9SIA (HM for short) 4.18 g Si (OEt) 4 , 30 g n-butanol, 7.8 g aluminum tributoxide and 1.
Mix 84g MCI (as a 0.1N alcohol solution) and ? 0"0 terror 0 minute heating, after cooling, 3.3g
820 and 182g+7) of EtOH were added. The solution was heated to 50° C. for 30 minutes and cooled.

PGI ram tetraethoxide and 5.48H Pb 2-ethylhexane and 25.5g non-butane and 1.78g
t7) HC1 (as a 0,IN ethanol solution) was mixed and the solution was refluxed for 2 hours, then cooled before use.

Pulverized reduced SrTiO3 in N2 atmosphere for the required time,
After contacting the alkoxide solution, the slurry was drained through a glass filter in a reducing atmosphere and then exposed to air for 90 minutes.
It was dried at 0°C for 16 hours. The dry powder was then heated in air to 550"0 (lh) for concentration. The temperature increase was from 6o to 240"C! I felt angry. During the concentration process, the remaining components were removed. If necessary, treatment in oxygen can be performed to increase the rate of oxidation. The concentrated powder was then shaped and sintered either as such or after mixing with a powdered complementary liquid phase.

Approximately 1.5 titania powder was added to form the pressurized disk.
It was mixed with polyvinyl butyl (PVB) in a proportion of % by weight. The required amount of titania was slurried with 20 g of PV liquid, stirred for 30 minutes, and then evaporated. Then PvP
Pour the coated powder through a sieve (300ILm mesh sieve) and use a stainless steel mold to weigh 2 to 5 tons.
/cm” to form a disk. Then,
To remove the binder, the molded body was heated in air at 550° C. for 1 hour (0.5-b) and then sintered.

Sintering is performed using Al2O3 connected to multiple introduction gas introduction pipes.
carried out in a tubular channel, with pure nitrogen gas as the plurality of inlet gases.
0/[1 (V/V) H2/N2 mixed gusts were used, respectively. Flow control for each gas was with rotating vanes and respective flow meters. By properly setting the controls, the true ratio of H2 and N2 in the furnace can be reduced to approximately 0.01$ and 5z
The ratio can be adjusted between 0.1% and 1z, preferably between 0.1% and 1z. The sintering temperature was varied between 900°C and 1500°C, and the sintering time was varied between 1 and several hours.

The electrodes on both sides of some discs were formed by applying metal paint or paste, such as Pt, Ag or Cu paste, and then sintering.The processing data and results are listed in Table 1 below. It should be noted that in some cases there was post-treatment (introducing air during cooling after sintering). This is described in Table ■.

Table■ When applying the first layer of aluminum silicate, during sintering,
It has the effect of hindering particle growth and improving the combination of ε and Q factor to some extent. Air cooling increases the Q factor and does not adversely affect the dielectric constant.

Example 4 The material of Example 3 and similar process operating parameters were again used. SrTiOz coated with reduction before sintering
The doped powder was mixed with powdered supplementary liquid phase and processed as follows. 78 wt% Pb0− and 22%
A mixture of Al2O3 and GeO2 (denoted as PGO) is
Melts at approximately 1000℃ (glass melting temperature) in the crucible,
After maintaining the molten state for a predetermined time (1 to 4 hours), it was cast in a stainless steel mold. The glass was prepared by the treatment described in Example 3 (polyethylene mill We/GO pole) from 1 to 5 lm.
It was crushed.

Then, coated SrTiO3 and predetermined crushed PG
Composition with O, having PVB (pre-melted)
Slurried in 20/80 V/V acetone/isopropanol solution. The slurry is a solid material (PVBvJ
There was 100 cc of 30 g solution. The slurry was then dried, processed and sintered as in Example 3.

The results for the sintered disk capacitors are shown in Table V below. The parameters are the same as those in Table I, with the addition of the amount (weight) of supplementary liquid phase and the condition of the aftertreatment air after sintering. In some cases, annealing (A) was performed at a temperature instead of simply cooling in air (C).

Table V Example 5 This example describes the application of diffusion processing a molten glass composition into a sintered ceramic. The reduction-doped strontium titanate is the same as in Example 3.4, and the processing conditions for sintering it into a disk are also the same.

Approximately 0.1 g of paste was applied to the sintered disk. This paste is prepared at the end of this application description by mixing approximately 3 g of solid with a small solution of 20 g of PVB and 120 g of n-butanol (approximately 0.1 g of solution). The disks were dried and heated to the diffusion temperature for a specified period of time. The first set of data is shown in Table VA below. In this case the semiconducting doped SrTiO3 particles are SrCO:
I 100g and Ti02541g and Nb2O512,8
9 g of H
Reduction was performed in 2/N2 gas. After crushing this material,
HM9SIA (Reference Example 3) infiltrated with solution, after normal processing, mixed with 5XPGO (Reference Example 4) and sintered as noted in Table VA, then various characteristic results of the resulting capacitors. The diffused phase was applied as shown in the table.

Thereafter, an electrode was deposited by sputtering.

Table VA As a further experiment, in the first doped SrTiOz,
A double coating of aluminum silicate was applied by the sol-gel process with the above-mentioned HM hot solution. In this case, no supplementary addition of sintering aid (PGO) was made. Less than 0.4% hydrogen was used during sintering in a nitrogen flow. The diffusion processing parameters, diffusion composition and results are shown in Table VB below.

Table VB The third experiment was conducted as the second experiment, with 8M sol-gel treatment, but no sintering aid was added. The sintering atmosphere was nitrogen and 0.4% or less of H2 added. Data are shown in Table VC.

Table VC "Effect of the invention"

Claims (23)

[Claims] (1) Nb, La, W, Co
semiconducting SrTiO_3 particles for use in making high dielectric constant insulators with internal grain boundary barrier layer ceramics suitable for high capacitance capacitors. In the manufacturing method, compounds of Br, Ti, and doped metals are combined, at least one of these compounds is an organic alkoxide compound, this alkoxide is converted into a gel by sol-gel technology in a state mixed with a non-alkoxide compound, and then dried. After that, the mixture is heated in a hydrogen or carbon monoxide atmosphere or in an inert gas.
A method for producing semiconductive SrTiO_3 particles, which is characterized by firing and finally pulverizing the powdered reduced product to a desired particle size. (2) impregnating powdered SrTiO_3 with a gel-like solution of niobium alkoxide and draining the liquid bulk from the shimeri powder;
Dry in air and in hydrogen or carbon monoxide atmosphere, 1300
A method for producing semiconductive SrTiO_3 particles according to claim 1, wherein the semiconductive SrTiO_3 particles are fired at a temperature of ~1500°C. (3) Powdered TiO_2 is impregnated with a gelled niobium alkoxide solution, the powder is drained and dried in air, mixed with the same amount of powdered SrCO_3, and heated at 1300 to 1500°C in a hydrogen or carbon monoxide atmosphere. A method for producing semiconductive SrTiO_3 particles according to claim 1, which involves firing. (4) Add a gel solution of titanium and niobium alkoxide to ammonia water while stirring and colliding the microparticles of gel material and the solution, separate and dry the particles, mix with the same amount of SrCO_3, and add hydrogen or The semiconductive Sr according to claim 1, which is fired in a carbon monoxide atmosphere.
Manufacturing method of TiO_3 particles. (5) Spraying a solution of titanium and niobium alkoxide into a stirred ammonia solution, slowly heating the solution to about 400°C to separate the particles, and then drying in air, and mixing with SrCo_3 to remove the mixture. Approximately 1000 in the air
The process grows the mixed oxides of strontium-titanium-niobium into very small particles, and also contains hydrogen or carbon monoxide and nitrogen, carbon dioxide or noble gases such as hydrogen or carbon monoxide. Reduction firing treatment is carried out in a mixed gas with an inert gas at a temperature not exceeding 1000°C, and during heating, substantially reduced particles grow, and after that, they can be easily crushed into particles of about 1 μm or more. The semiconductive SrTiO according to claim 4, which is
_3 Production method of particles. (6) The reducing atmosphere used in the subsequent firing process is a mixed gas of hydrogen or carbon monoxide and an inert gas such as nitrogen, rare gas, or carbon dioxide, and the firing temperature is 950-1
A method for producing semiconductive SrTiO_3 particles according to claim 1, wherein the temperature is 310°C. (7) A compound of Sr, Ti, and a doped metal is combined, at least one of the compounds is an organic alkoxide compound, and this alkoxide is mixed with a non-alkoxide compound and turned into a gel by sol-gel technology, and then dried. The mixture is then calcined in a hydrogen or carbon monoxide atmosphere or an inert gas, and finally the powdered reduced product is crushed to the desired particle size to produce semiconductive SrTiO_3 particles, and this semiconductive In a method for producing a sintered body of a high dielectric constant insulating internal grain boundary layer ceramic using SrTiO_3 particles, (a) a metal compound that helps sintering, that is, lowers the sintering temperature and facilitates the formation of an insulating barrier layer; the liquid phase of is mixed with doped (Nb)SrTiO_3 particles,
(b) The mixed strontium is pressurized and molded into the shape of an insulator of a capacitor, (c) The molded body is heated at 1000 to 1300°C, nitrogen, and H_
Sintering in 2/N_2 or Co/CO_2 mixed gas,
A manufacturing method for high dielectric constant ceramics. (8) Step (a) is to mechanically mix doped SrTiO_3 particles with a sintering aid of a powdered mineral composition, and the mineral composition is selected from Pb, Ge, Bi, P, and Ba. A method for producing a high dielectric constant ceramic according to claim 7, in which the ceramic is an oxide. (9) Sol-gel technology, i.e. impregnating particles of doped SrTiO_3 powder with metal alkoxide solution, gelling the alkoxide and thus converting it into particles (met
step (a
) A method for producing a high dielectric constant ceramic according to claim 7. (10) The method for producing a high dielectric constant ceramic according to claim 9, wherein the alkoxide is selected from alkoxides of Pb, Ge, Bi, and B, and the composite metal oxidation phase is comprised of lead germanate and lead boron bismuthate, respectively. . (11) In step (a), the doped SrTiO_3 is first supplementally coated with an aluminum silicate layer, and a gel-like solution of aluminum alkoxide and silicon alkoxide is used for the supplement.
The manufacturing method of the high dielectric constant ceramic described in Section. (12) Doped SrTiO_3 includes the claims (
A method for producing a high dielectric constant ceramic according to claim 8, comprising a first coating of a metal oxide such as (9) or (11). (13) The method for producing a high dielectric constant ceramic according to claim 7, wherein the sintered body is heat-treated in air after sintering. (14) The method for producing a high dielectric constant ceramic according to claim 13, wherein the heat treatment involves cooling the still hot molded body according to a set cooling program. (15) The method for producing a high dielectric constant ceramic according to claim 13, wherein the heat treatment is performed by cooling the sintered body in an inert gas and then annealing it in air. (16) Place the sintered body in the air from the sintering temperature to room temperature for 50~
Claim 14 cooled at a rate of 250°C/hr
The manufacturing method of the high dielectric constant ceramic described in Section. (17) Cool the sintered body from the sintering temperature to the set temperature in the sintering atmosphere, and then cool it in the air at 50-250℃/
A method for producing a high dielectric constant ceramic according to claim 14, wherein the ceramic is cooled at a rate of hr. (18) Claim 17, in which the set temperature is 800 to 1100°C and the cooling rate is 150 to 200°C/hr.
A method for producing a ceramic sintered body as described in 2. (19) After the first cooling, the sintered body was placed in air or oxygen for 800 hrs.
The method for producing a high dielectric constant ceramic according to claim 15, which is reheated at ~1200°C for 0.5 to 5 hours. (20) A glass-forming composition is applied to the sintered body prior to reheating, and the composition is melted and diffused into the ceramic at an annealing temperature to strengthen the barrier boundary insulating phase. The manufacturing method of the high dielectric constant ceramic described in Section. (21) The glass-forming composition is a slurry of a powdered mineral composition doped on the surface of the sintered body.
The manufacturing method of the high dielectric constant ceramic described in Section. (22) The glass-forming composition comprises the compounds PbO, GeO_
2, B_2O_3, Bi_2O_3, PbF_2, Cu
22. The method for producing a high dielectric constant ceramic according to claim 21, which comprises at least one of O, SrTiO_3. (23) The slurry contains a powdered metal, and the metal becomes a metal film on the surface of the sintered body during the diffusion treatment, and is then used as a capacitor electrode.
The manufacturing method of the high dielectric constant ceramic described in Section.