JPS63319214A - Powder material for condenser - Google Patents

Abstract

PURPOSE:To obtain powder material for condenser possible to form a thin film having easily-sinterability and high strength by specifying composition consisting of Pb, Ba, Sr, Ca, Mg, Zn, Ni, Nb, Ti and O and by grinding to powder having specified specific surface area. CONSTITUTION:The powder material is the powder having general formula Pb1-xAx(B1/3Nb2/3)yTi1-yO3, where A is at least one kind of Ba, Sr and Ca, B is at least one kind of Mg, Zn and Ni, x=0.1-0.9 and y=0.1-0.9, and 3-15m<2>/g specific surface area, and is suitable as powder raw material of composite perovskite structure compd. and its solid soln. for condenser. The powder raw material is obtd. as powder having about 0.05-0.5mum particle diameter, for example, by calcining the ppt. obtd. by bringing solutions of Pb, A, B, Nb and Ti component into multistage contact with a soln. for forming ppt. by the multistage wet method. The powder raw material above-mentioned has characteristics such as easily-sinterability, uniformity, low cost, high bulk density, etc., and furthermore, is possible to be easily made into a thin film having a thickness of about <=50mum and high strength.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a raw material powder of perovskite and its solid solution for capacitor materials.

Perovskites and their solid solutions are widely used as capacitor materials. Recently, it has been desired to further improve this functionality, and raw material powders for perovskites and their solid solutions that meet these demands are required, which are easy to sinter, have uniformity, have high bulk density, and are low cost. ing.

(Prior art and its problems) Conventionally, raw material powders for perovskite and its solid solution for capacitor materials have been manufactured by a dry method in which oxides, etc. are mixed and calcined.
60, JP-A-61-251563, JP-A-61-2515G4, etc.

The dry method is a method in which compounds of constituent raw materials are mixed in a dry method and then calcined. However, with this method, the particle size of the obtained raw material powder is large, several μm, and the sinterability is not sufficient, so it is difficult to obtain perovskite with excellent functionality.

In particular, in order to increase the capacitance of the capacitor, 50
It is necessary to create a multi-M structure with a thin film of 11 m or less, but when powder with a large particle size produced by a dry process was used in a multilayer capacitor, it did not exhibit sufficient functionality.

(Object of the Invention) The object of the present invention is to develop a perovskite and its solid solution for capacitor materials, which meet the four requirements of easy sinterability, uniformity, low cost, and high bulk density, and which can easily form a thin film of 50μIn or less. The purpose is to provide raw material powder.

(Technical Means for Solving the Problems) The inventors of the present invention have conducted intensive research to achieve the above-mentioned object, and as a result, have arrived at the present invention.

The present invention is based on the general formula % (where A represents at least one of Ba, Sr, and Ca, B represents at least one of Mg, Zn, and Ni, and x
= 0.1-0.9, y = 0.1-0.9. The present invention relates to a powder for capacitor materials, which is a raw material powder of perovskite and its solid solution represented by the following formula, and has a specific surface area of 3 to 15 to 7 g.

In the present invention, the A component of perovsky 1 and its isosolutes represented by the general formula % is at least one of Ba, Sr, and Ca, the B component is at least one of Mg, Zn, and Ni, and Pb1xA
x(B1/3"b2/3)yPb7-XAX component in Til-yo3 and (R1/3 N b2/3), T
The atomic ratio of the j7□ component is usually 1.0, but non-stoichiometric perovskites in which this atomic ratio is shifted to a value higher or lower than 1.0 are also included.

Moreover, X and y in the above general formula are X = 0.1 to 0
．． 9, y = a numerical value of 0.1 to 0.9, and if it deviates from this range, it is not preferable because it will cause problems in terms of characteristics.

The raw material powder of perovskite and its solid solution having the above composition has a particle size in the range of 0.05 to 0.5 μm, and is preferably as close to spherical as possible. For this purpose, it is necessary that the powder has a specific surface area of 3 to 15 i/g.

If the particle size is larger than 0.5 μm, the sinterability is poor, it tends to be difficult to form a thin film, and the resulting thin film also has low strength. In addition, when forming a thin film with a particle size smaller than 0.05 μm, it is difficult to form a green sheet, and the sheet 1
-A large amount of binder and the like is required for formation, and the resulting sintered body also has many pores, which is not preferable.

The method for obtaining the raw material powder of perovskite and its solid solution of the present invention is such that the shape of the obtained powder is close to spherical or cubic, and the specific surface area is 3 to 15 rrr.
As long as it is within the range of /g, there are no particular limitations, but examples include a sol-gel method, a coprecipitation method, a multi-stage wet method, a dry-pulverization method, and the like.

The multi-stage wet method and dry-pulverization method will be explained below.

In the multi-stage wet method, the general formula Pb1xAx(B1/3Nb2/3)yTil-yO3
The pb acid component A component, B component, Nb component and T
The powder for capacitor materials of the present invention can be prepared by bringing each component solution of component i into contact with one or more precipitate-forming liquids in multiple stages to sequentially form precipitates, and then calcining the obtained precipitates. is obtained.

Component compounds for preparing a solution of a compound containing a metal element as a component of perovskite and its solid solution include, but are not particularly limited to, their hydroxides, carbonates, oxysalts, sulfates, nitrates, and chlorides. etc. $F, machine salt,
It is appropriately selected from organic acid salts such as acetates and oxalates, oxides, and the like. These are generally used as aqueous solutions, but if they are not soluble in water, they can be made soluble by adding acid.
Insoluble raw materials may be used as a suspension solution.

Also, an alcohol solution may be used instead of an aqueous solution.

Precipitation forming liquids include ammonia, ammonium carbonate,
Examples include solutions of ammonium hydrogen carbonate, oxalic acid, ammonium oxalate, caustic alkali, alkylamine, and the like. Examples of the alkylamine include primary amines having a lower alkyl group such as methylamine, ethylamine, propylamine, and butylamine, primary amines having a lower alkyl group such as cyclohexylamine, tertiary amines having a lower alkyl group such as dimethylamine and diethylamine, and triethylamine. Mention may be made of tertiary amines having lower alkyl groups such as

In the multi-stage wet method, each solution of the constituent components is brought into contact with one or more precipitate-forming liquids in multiple stages to sequentially generate precipitates, so that the shape of the primary particles of each precipitate is non-uniform; The shape of the secondary particles, which are the aggregates, is uniform, and the size of the secondary particles is an appropriate particle size of about submicrons, resulting in good dispersibility.

To form a precipitate of the constituent components, a solution of each constituent component may be added to the precipitate forming liquid while stirring the precipitate forming liquid, or vice versa. The addition is preferably carried out while sufficiently stirring the liquid.

Also, when forming a precipitate, for example, after forming a precipitate of one component, it is washed with water to remove anions.

After that, the precipitate may be dispersed in fresh water or alcohol, and further a solution of other components and a precipitate forming liquid may be added to form a precipitate.

The precipitate obtained by the above method is washed with water or the like by a conventional washing method, separated in a furnace, dried, and then calcined. Drying may be performed under atmospheric pressure or under reduced pressure.

If the calcination temperature is too low, the dehydration and thermal decomposition of the precipitate will be insufficient, and if it is too high, the powder will become coarse. be.

In the dry-milling method, compounds containing each metal element of perovskite and its solid solution, such as oxides and carbonates, are mixed dry using a ball mill or the like, and this mixture is mixed using a centrifugal flow mill or After crushing and mixing with an attritor, etc., and calcining at a temperature of 500 to 1200°C, the specific surface area is reduced to 3 by using a centrifugal fluid mill, etc.
The powder for capacitor materials of the present invention can be obtained by pulverizing the powder to a range of 15 rrr/g.

(Example) The present invention will be explained in more detail by showing Examples and Comparative Examples below.

Example l PbO,73BaO,27[Zn1/3Nb2/310
．． 6T'0.4°3 Niobium pentachloride (Nb CfJ5)
10.81 g was dissolved in 100 mρ of ethanol, and 500 mN of 6N aqueous ammonia was added. Add to this 300mj of lead nitrate [Pb(No3) 2124.18 g and barium nitrate [Ba(NO3)2] 7.06 g!
A solution of the solution in water was added to form a precipitate. Furthermore, 7.5 g of titanium tetrachloride (Ti Cj14) was added to 70 g of water.
A solution dissolved in 0 mjl was added to form a precipitate. The solution containing the precipitate was allowed to stand still, the supernatant liquid was removed, fresh water was added, the mixture was thoroughly stirred, the solution was left to stand again, and the supernatant liquid was removed. 1
A solution of 0 mN in 100 m of water and O was added.

Add zinc nitrate [Zn(No3)2.6H20] to this solution 5
A solution of 95 g dissolved in 100 ml of water was gradually added to form a precipitate. After washing, filtering, and drying this precipitate, the composition was analyzed, and the elemental composition was the same as that of the starting material. Further, this precipitate was calcined at 780°C for 4 hours. The resulting powder was ball milled in the presence of ethanol, and part of it was observed using a transmission electron microscope. The particle size was uniform at about 0.2 μm, and the specific surface area was 5.2 rrr/g. Ta. Moreover, the perovskite structure was 98% or more.

0.8% by weight of polyvinyl alcohol (hereinafter abbreviated as PVA) was added to the above powder, molded at It/cJ, and sintered at 950°C for 10 hours in a lead atmosphere. As a result, the density of the sintered body was the theoretical density. It was 99% of the total.

Also, when we measured the electrical properties, we found that the dielectric constant was 12,800,
tan δ 0.9%, specific resistance 1. It was 1×1012Ω'on.

Examples 2 to 4 Products having the compositions shown in Table 1 were manufactured by the same method as in Example 1, and their electrical properties were measured. The results are shown in Table 2.

Example 5 PbO,73Ba0.27 [Zn1/3Nb2/31
0.6” '0.403 Lead oxide (pbo), barium carbonate (BaCo3), zinc oxide (zno), niobium oxide (Nb205) and titanium oxide (T i O
2) were weighed out to have the above composition, thoroughly mixed in a ball mill, and then pulverized and mixed in a centrifugal fluid mill. This 14 opening 0.463-319214
(4) After calcining the mixture at 850°C for 2 hours, it was further pulverized using a centrifugal fluid mill. The particle size of the obtained powder is 0
．． The temperature was approximately 408°C, and the specific surface area was 3.6 d/g. 0.8% by weight of PVA was added to the obtained powder to give 1
After molding at t/cxM, it was sintered at 1000°C for 5 hours. The density of the sintered body is 989% of the theoretical density, and the electrical properties are dielectric constant 11600, tan δ 0.7%, and resistivity 1. It was 1×1013Ω・me.

Comparative example l PbO, 73Ba0.27 [7'1/3Nb2/3J
O,6'ri0.4°3 Lead oxide (pbo), barium carbonate (BaCo3), zinc oxide (ZnO), niobium oxide (Nb205) and titanium oxide (T i O
2) were weighed out so as to have the above composition, and after thoroughly mixing them in a ball mill, this was calcined at 900° C. for 2 hours. The particle size of the obtained powder is about 1.0 μm,
Is the specific surface area 1.5rr? /g. After adding 0.8% by weight of PVA to the obtained powder and molding it at it/cJ, it was sintered at 950° C. for 10 hours. The density of the sintered body is 94.5% of the theoretical density, and the electrical properties are a dielectric constant of 630.
0, tan δ 3.6%, specific resistance 1. lX1011Ω-(
).

(Effect of the invention) General formula Pb1xAx(B1/3Nb2/3)yTil
-yO3 (where A represents at least one of Ba, Sr, and Ca, B represents at least one of Mg, Zn, and Ni, x = 0.1 to 0.9, y = 0.1 to 0.
The value is 9. ) By setting the specific surface area of the raw material powder of perovskite and its solid solution to 3 to 15 nf/g, it becomes easy to sinter, and high strength can be obtained when thinning the film, making it possible to make multilayer capacitors. A powder with excellent performance as a material is obtained.

Claims (1)

[Claims] General formula Pb_1_xA_x(B_1_/_3Nb_2
___/_3)_yTi_1-_yO_3 (However, A is B
a, Sr, and Ca, and B represents Mg, Z
n, represents at least one type of Ni, x = 0.1 to 0.9
, y=0.1 to 0.9. ) A powder for a capacitor material, which is a raw material powder of a compound with a composite perovskite structure (hereinafter referred to as perovskite) and a solid solution thereof, and has a specific surface area of 3 to 15 m^2/g.