JP2682261B2 - Method for producing ceramic raw material powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic raw material powder, and more particularly to a method for producing a ceramic raw material powder useful as a material for ceramic electronic parts.

[0002]

2. Description of the Related Art Generally, when manufacturing a ceramic electronic component, it is intended to modify or improve its electrical characteristics by doping various elements into a base ceramic composition, for example, a ceramic dielectric basic composition. Is being done. In this case, when the element to be doped, that is, the dopant is introduced into the basic composition, a method of coating the compound of the dopant on the surface of each particle of the basic composition powder of the ceramic dielectric is adopted. As the coating method, (a) a dry method in which a carbonate or oxide of a dopant or a mixture thereof is added to the powder of the basic composition of the ceramic dielectric, and the mixture is pulverized and then calcined, (b) the ceramic dielectric An aqueous solution containing dopant ions is added to the slurry of the basic composition powder of 1., a precipitating agent is added to this to form a precipitate, which is filtered, dried, and calcined, and (c) A method is known in which a solution of a compound of a binder and a dopant is added to a basic composition powder of a ceramic dielectric to make a slurry, which is spray-dried, granulated, and then calcined.

[0003]

However, (A)
In the dry method of, it is impossible to uniformly disperse the carbonates or oxides of a plurality of dopants in the basic composition powder, and the compound of the dopant segregates,
The individual particles of the basic composition powder cause a difference in doping effect, which makes it difficult to obtain desired characteristics, and there is a problem in that there are many variations in the characteristics of the ceramic electronic component.

On the other hand, the wet method (b) has improved dispersibility as compared with the dry method, but it cannot be said to be sufficient, and moreover,
It may be difficult to co-precipitate multiple dopants with a single precipitant. For example, Sr, Ca and Mg can be precipitated as a complex carbonate by reacting with carbonate ion (CO ₃ ^-2 ), but Ti ^{+4 and the} like cannot be precipitated as carbonate with carbonate ion. Is. Further, when an ammonium salt, which is more advantageous than a soda salt, is used as a precipitant, elements such as Zn, Mn, Ni, and Co form an ammine complex and become soluble, so that a precipitate cannot be generated. There is.

Further, in the method (c), when the basic composition powder is granulated, a dopant is adhered to the surface of the particles, but it may be organic depending on the kinds of anions and cations which coexist when forming the slurry. There is a problem that gelation occurs due to interaction with the binder, and it becomes impossible to uniformly disperse and attach the dopant.

Therefore, the object of the present invention is to obtain a ceramic material powder in which the surface of individual particles is uniformly coated with a thin film layer containing a dopant.

Means for Solving the Problems The present invention, as a means for solving the above problems, comprises mixing a ceramic base composition powder with an organic solvent and at least one surfactant to form a slurry, and at least adding the slurry to the slurry. An organic compound containing a dopant ion, which is soluble in one type of the organic solvent, is added and mixed, and the slurry is dried to obtain a dry fine powder of the basic composition in which the particle surface is coated with the organic compound containing a dopant ion. It was obtained and calcined.

As the organic solvent, those having a boiling point of 150 ° C. or lower are preferable, and typical examples thereof include alcohols such as methanol, ethanol and butanol, aromatic solvents such as benzene, toluene and xylene, and methyl ethyl ketone. Ketones such as, but not limited to.

As the surfactant, any known one may be used alone or in combination, and typical examples thereof include carboxylate, sulfonate and the like.
Sulfate ester salt, phosphate ester salt, aliphatic amine salt and its ammonium salt, aromatic quaternary ammonium salt,
Ionic surfactants such as heterocyclic quaternary ammonium salts;
Polyoxyethylene alkyl ether, single chain length polyoxyethylene alkyl ether, polyoxyethylene 2
Primary alcohol ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene glycerin fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyethylene glycol fatty acid ester, propylene glycol fatty acid ester, fatty acid alkanolamide, polyoxyethylene fatty acid amide, polyoxyethylene alkylamine And non-ionic surfactants such as; and amphoteric surfactants such as carboxybetaine, sulfobetaine, aminocarboxylic acid salts, and imidazoline derivatives.

Typical examples of the organic compound containing a dopant ion (hereinafter referred to as a dopant-containing compound) include organic acid salts, alkoxides and other acetylacetonates, but the organic compounds are not limited to these. Any organic acid can be used, and representative ones include naphthenic acid and octylic acid. Any alkoxide can be used, but an alkoxide having 15 or less, preferably 8 or less carbon atoms is desirable. As typical ones, for example, when titanium is taken as an example, titanium isobutoxide (Ti (OC ₄ H ₉ ) ₄ ), titanium isopropoxide (Ti (OC ₃ H ₇ ) ₄ ), titanium ethoxide, dibutoxide. Siege triethanol over aminate titanium, Jibutokishiji (2- (hydroxyethylamino) ethoxy) titanium _{(Ti (C 4 H 9 O} ) 2 · _{[N (C 2 H 4 OH)} 2 (C 2 H 4 O) ] ₂₎
And the like.

[0010]

The ceramic base composition powder is mixed and ground in an organic solvent together with a surfactant before adding the compound containing the dopant, whereby the base composition powder is finely ground and the surface of the particle is coated with the surfactant. Will be adsorbed, and a slurry in which the basic composition powder is sufficiently dispersed without agglomeration is obtained, and when a dopant-containing compound is added to and mixed with this, the surfactant adsorbed on the particle surface of the basic composition powder Due to the action of the layer, the dopant-containing compound is preferentially adsorbed on the lipophilic base side, and the dopant-containing compound is dispersed in a uniformly coated form on the particle surface of the basic composition powder. By drying this slurry by a spray drying method or the like, it is possible to obtain a dry fine powder in which the particle surface of the basic composition powder is uniformly coated with a thin layer of a dopant-containing compound, and the dry fine powder is calcined. Alternatively, by roasting, the dopant-containing compound becomes an oxide to form a ceramic raw material powder in a form in which the particle surface of the basic composition powder is covered.

Further, when the dopant-containing compound is dispersed, a plurality of dopant-containing compounds are used, and they are compounded in a predetermined ratio so that they form a perovskite type compound or a complex perovskite type compound, and their thin layers are formed into a basic composition. If formed on the surface of the particles of the product powder, calcination forms particles of the basic composition powder as nuclei, and the surface is coated with a perovskite-type or complex perovskite-type compound to form a core-shell structure powder.

[0012]

EXAMPLES Example 1 100.00 parts by weight of BaTi
An O ₃ powder was added in an amount of 0.43 parts by weight in terms of an active ingredient and an anionic surfactant (polymeric carboxylic acid surfactant) and 10
It was put into a polyethylene ball mill together with 0 part by weight of ethanol and 500 parts by weight of a partially stabilized zirconium (PSZ) boulder having a diameter of 5 mm and pulverized and dispersed for 16 hours to obtain a slurry. Cerium naphthenate was added to this slurry in an amount of 0.1.
0193 mol, and titanium isopropoxide 0.01
After adding 93 mol and carrying out dispersion treatment for 5 hours, it was dried by a spray dry method. The obtained dry powder was calcined at 1000 ° C. to obtain 4.5 mol% Ce-doped barium titanate powder.

The distribution state of Ce on the surface of the dry powder was subjected to mapping analysis by an X-ray microanalyzer (XMA), and it was confirmed that Se was not dispersed and was uniformly dispersed on the particle surface.

(Example 2) 100.00 parts by weight of BaT
An amount of 0.43 parts by weight of an iO ₃ powder as an active ingredient and an anionic surfactant (polymeric carboxylic acid type surfactant) and 1
00 parts by weight of ethanol and 5 mmφ PSZ boulder (5
(100 parts by weight) and charged into a polyethylene ball mill and pulverized and dispersed for 16 hours to obtain a slurry. Cobalt naphthenate was added to this slurry as cobalt oxide.
05 parts by weight, 2.00 parts by weight of niobium butoxide in terms of niobium oxide, and 0.6 parts by weight of neodymium octylate in terms of neodymium oxide were added, followed by dispersion treatment for 5 hours, and then dried by spray drying. . The resulting dry powder was calcined at 1000 ° C. It was confirmed that the calcined powder had a so-called core-shell structure in which barium titanate particles were used as nuclei, and Nb, Nd, and Co oxides were surrounded in a layered manner.

Mapping analysis of the oxide (Nb, Nd, Co) on the particle surface of the dry powder and the calcined powder by XMA was carried out. As a result, segregation of these elements was observed in both powders. It was confirmed that they were not evenly dispersed.

(Example 3) 100.00 parts by weight of BaT
0.43 parts by weight of amphoteric surfactant, 100 parts by weight of ethanol, and 5 mmφ of P were added to the iO ₃ powder in terms of active ingredient.
It was put into a polyethylene ball mill together with SZ boulders (500 parts by weight), and pulverized and dispersed for 16 hours to obtain a slurry. Lead octylate was added to this slurry as 9.5 PbO.
75 parts by weight, zirconium butoxide (2.637 parts by weight in terms of ZrO ₂₎ and titanium butoxide (1.710 parts by weight in terms of TiO ₂₎ were added, followed by dispersion treatment for 5 hours, and then dried by a spray dry method. The obtained dry powder was calcined at 700 ° C. It was confirmed that the calcined powder had a core-shell structure in which barium titanate particles were the core, and a lead zirconate titanate layer surrounded the core.

The distribution states of Pb, Zr and Ti on the surface of the particles of the dry powder and the calcined powder were measured by XMA.
As a result of mapping analysis by the above, no segregation of these elements was observed in the two powders, and it was confirmed that they were uniformly dispersed. When the X-ray diffraction analysis was performed on the calcined powder, the product was lead zirconate titanate (PZT).
Was confirmed.

[0018]

As is apparent from the above description, according to the present invention, an oxide layer can be uniformly formed on the surface of a ceramic base powder, and a metal forming the oxide layer is appropriately selected. By doing so, it is possible to form a composite perovskite type compound layer on the surface of the base powder and easily obtain a powder having a core-shell structure, and obtain an excellent effect.

Claims (5)

(57) [Claims] 1. A ceramic base composition powder is mixed and ground with an organic solvent and at least one surfactant to form a slurry, and an organic compound soluble in at least one organic solvent and containing a dopant ion is added to the slurry. And mixing, and drying the slurry to obtain a dry fine powder of the basic composition whose particle surface is coated with an organic compound containing a dopant ion, and calcining this to produce a ceramic material powder. . 2. The surfactant is an ionic surfactant,
The method for producing a ceramic raw material powder according to claim 1, wherein the method is at least one of a nonionic surfactant and an amphoteric surfactant. 3. The method for producing a ceramic raw material powder according to claim 1, wherein the surfactant is soluble in an organic solvent. 4. The surfactant is water-soluble.
Or the method for producing the ceramic raw material powder according to item 2. 5. The method for producing a ceramic raw material powder according to claim 1, wherein the dopant-containing compound comprises a plurality of compounds that produce a predetermined perovskite-type or complex perovskite-type compound by calcination.