JPH0733441A - Production of multiple oxide - Google Patents

Abstract

PURPOSE:To produce A(B'1/3B''2/3)O3 type multiple oxide powder contg. ordered metals B', B'' as fine powder excellent in sinterability. CONSTITUTION:When metal alkoxides are hydrolyzed to produce A(B'1/3B''2/3)O3 type multiple oxide powder, 0.5-10 times (mol) as much water as alkoxy groups is added to a soln. of mixed or multiple alkoxide consisting of alkoxide of a metal B' and alkoxide of a metal B'' in an org. solvent, alkoxide or hydroxide of a metal A is added to the resulting hydrolyzate and hydrolysis is further carried out. The B' alkoxide is alkoxide of one or more kinds of elements selected among Mg, Co, Ni, Zn and Ca, the B'' alkoxide is alkoxide of one or more kinds of elements selected among Ta, Nb and Sb and the A alkoxide is alkoxide of one or more kinds of elements selected among Ba, Sr and Ca.

Description

Detailed Description of the Invention

[0001]

The present invention relates to A (B ') used as a raw material powder for electronic material ceramics such as dielectric materials.
_The present invention relates to a method for producing a _1/3 B ″ _2/3 ) O ₃ composite oxide.

[0002]

2. Description of the Related Art Generally, a complex oxide having a perovskite structure is important as an electronic material because it has electrical characteristics such as dielectricity and piezoelectricity. Among these complex oxides having a perovskite structure, especially A (B '
_1/3 B ″ _2/3 ) O ₃ -based composite oxides are used as microwave dielectric materials such as dielectric resonators because they have a small dielectric loss in a high frequency region, that is, a high Q value.

Microwave dielectric materials are commonly oxides,
Manufactured by molding and firing A (B ' _1/3 B ″ _2/3 ) O ₃ -based composite oxide powder prepared by mixing carbonates, hydroxides, etc. and calcining (solid phase reaction method) However, this A
Most of the (B ′ _1/3 B ″ _2/3 ) O ₃ -based composite oxides are difficult to sinter and hardly densify by ordinary firing.
Therefore, A (B 'produced by the usual firing method)
_Since a high Q value cannot be obtained with the _1/3 B ″ _2/3 ) O ₃ -based composite oxide, in order to produce the dense sintered body, Mn
A method of adding a sintering aid such as, a method of firing by rapidly raising the temperature, and the like have been developed.

On the other hand, a sol-gel method using a metal alkoxide as a starting material is generally known as a method for producing an easily sinterable oxide powder. In this sol-gel method, a metal alkoxide is dissolved in an organic solvent and hydrolyzed to form a sol or gel composed of a metal oxide, a metal hydroxide, etc., and dried and heated to form an oxide powder. Is the way to get. When the oxide powder prepared from this metal alkoxide solution is molded and fired, the temperature is much lower than when using conventional powder raw materials made by calcination of inorganic compounds such as oxides and carbonates. Sintering and densification occur and a highly pure and homogeneous oxide sintered body is obtained at a low temperature.

Fine powders have also been produced by the sol-gel method for A (B ′ _1/3 B ″ _2/3 ) O ₃ -based composite oxides (for example, JP-A-58-199716). .
Therefore, the A (B ′ _1/3 B ″ _2/3 ) O ₃ -based composite oxide powder prepared by hydrolyzing the metal alkoxide is fine and has very good sinterability, and the sintering aid is used. Even if it does not exist, it can be densely sintered at a low firing temperature.

[0006]

It is very important that the microwave dielectric material is required to have a high dielectric constant, excellent temperature stability, and low loss, that is, a high Q value. Perovskite structure A (B ' _1/3
In order to obtain a high Q value in the B ″ _2/3 ) O ₃ composite oxide, it is necessary to increase the sintered density and further regularize the metals B ′ and B ″. In the conventional solid-phase reaction method, 16
After sintering at around 00 ° C, 145 for ordering
It had to be annealed at 0 to 1600 ° C. for a long time (eg 100 hours).

Further, in the sol-gel method, a powder prepared by simply hydrolyzing a mixed alkoxide of metals A, B ', B "can form a dense sintered body at a low firing temperature, but it is ordered. Therefore, it was necessary to anneal and regularize as in the solid-phase reaction method.

Therefore, the present invention is a method for producing an A (B ′ _1/3 B ″ _2/3 ) O ₃ -based composite oxide powder by hydrolyzing a metal alkoxide, and in the method, a dense sintering is performed at a low firing temperature. A body is obtained and the metal B'and B "are ordered A (B '
It is an object of the present invention to provide a method for producing _1/3 B ″ _2/3 ) O ₃ -based composite oxide powder.

[0009]

The present invention has been made to achieve the above object. That is, in a method for producing an A (B ′ _1/3 B ″ _2/3 ) O ₃ -based composite oxide powder by hydrolyzing a metal alkoxide, a mixture or composite of an alkoxide of metal B ′ and an alkoxide of metal B ″ is used. Water in an organic solvent solution of the alkoxide is added in an amount of 0.5 to 10 mol times with respect to the alkoxy group, and the alkoxide or hydroxide of the metal A is added to the obtained hydrolysis product.
It is further hydrolyzed. In the above manufacturing method, the B'alkoxide is Mg, Co, Ni, Z.
n, Ca alkoxide, B ″ alkoxide is Ta, N
b, Sb alkoxide, and A alkoxide are Ba,
Sr, Ca alkoxide.

The present invention will be described in detail below. The obtained A (B ′ _1/3 B ″ _2/3 ) O ₃ composite oxide was filtered,
It is separated from the solvent by ultrafiltration, centrifugation, etc. and dried to obtain a sintering raw material powder. If necessary, this powder may be calcined and used.

The composite alkoxide, which is also called a double alkoxide, is a metal alkoxide containing a plurality of different metals in one molecule. In the case of a composite alkoxide of B ′ alkoxide and B ″ alkoxide, its chemical formula is
It is represented by B ′ [B ″ (OR) ₆ ] ₂ , where OR is an alkoxy group.

The alkoxy group of the metal alkoxide is not particularly limited, but examples thereof include methoxy group, ethoxy group, butoxy group, propoxy group, methoxyethoxy group,
An ethoxy ethoxy group or the like can be used.

The organic solvent for dissolving the metal alkoxide is not particularly limited as long as the metal alkoxide of the present system is soluble, but alcohols such as methanol, ethanol, butanol, propanol, methoxyethanol and ethoxyethanol, ethers, benzene, Toluene, xylene, etc. can be used.

The amount of water used for mixing the alkoxide of the metal B'and the alkoxide of the metal B "or for hydrolyzing the complex alkoxide is appropriately 0.5 to 10 times the mole of the alkoxy group. If the amount is less than twice, the alkoxide of metal B ′ and the alkoxide of metal B ″ are not sufficiently hydrolyzed, so that an ordered A (B ′ _1/3 B ″ _2/3 ) O ₃ -based perovskite powder cannot be obtained. Even if the molar ratio is exceeded, an ordered A (B ′ _1/3 B ″ _2/3 ) O ₃ -based perovskite powder can be obtained, but the amount of added water increases and it takes time to separate the oxide powder. It is not realistic because it requires a large amount or the reaction container becomes too large.

The amount of water used for the hydrolysis after the addition of the alkoxide or hydroxide of the metal A is appropriately from 10 to 10 times the molar amount of all the alkoxy groups remaining in the reaction system. If the amount is less than equimolar, the hydrolysis becomes insufficient and a crystalline A (B ′ _1/3 B ″ _2/3 ) O ₃ -based perovskite powder cannot be obtained. It is not practical because the amount of oxide powder increases, it takes time to separate the oxide powder, and the reaction vessel becomes too large, so that heating / reflux may be performed during or after the hydrolysis of the above two. In addition, an acid as a catalyst in the water of hydrolysis,
Alternatively, alkali may be added.

[0016]

The regularization of A (B ' _1/3 B ″ _2/3 ) O ₃ system perovskite is performed by the B ′ ion and the B ″ ion in the crystal lattice.
By regularly arranging three layers in the order of B'-B "-B" as one cycle. If a mixed or complex alkoxide of B ′ alkoxide and B ″ alkoxide is previously hydrolyzed, a cluster or gel ordered into B′-B ″ -B ″ via oxygen is produced. The hydrolysis product and metal In order to react the alkoxide or hydroxide of A, B'and B "have already been ordered A (B ' _1/3 B"
_2/3 ) O ₃ based perovskite powder can be produced.

[0017]

EXAMPLES A (B ′ _1/3 B ″ in the present invention will be described below.
_The method for producing a _2/3 ) O ₃ -based composite oxide and the A (B ′ _1/3 B ″ _2/3 ) O ₃ -based composite oxide obtained thereby will be specifically described based on Examples. However, the present invention is not limited to these examples.

Example A (B 'consisting of the elements A, B', B "shown in Table 1
_{A 1/3} B ″ _2/3 ) O ₃ -based composite oxide was prepared as follows: B ′ ethoxide and B ″ ethoxide were added to ethanol in a molar ratio of 10: 10
A double alkoxide of B'and B "is prepared by heating and refluxing for a period of time. Water diluted with an equal weight of ethanol is added to this solution for hydrolysis. Next, A ethoxide or A hydroxide is converted into A: After adding B ′: B ″ at a molar ratio of 3: 1: 2, 10-fold molar water of the residual alkoxy group is added dropwise, and the mixture is heated under reflux for 5 hours. The precipitate was filtered and dried to obtain an A (B ' _1/3 B ″ _2/3 ) O ₃ powder. The order S was determined from the X-ray diffraction measurement of this powder based on the following formula.

[0019]

[Chemical 1] Here, (I ₁₀₀ / I _110,102 ) _obs. Is the observed (100) regular lattice line intensities (110), (102)
It is the observed value standardized by the baseline of. On the other hand, the intensity ratio (I ₁₀₀ / I
_110,102 ) _order .
It is 3/100.

Further, after the powder was calcined, it was molded and fired. The density of the obtained sintered body was measured by the Archimedes method, the sintered body was annealed at various times, and the annealing time at which the regularity was 0.95 or more was examined.

The alkoxides of Comparative Examples A, B ', B "were added to ethanol so that the molar ratio of A: B': B" was 3: 1: 2, and the mixture was stirred. Using this solution, A (B '
_{The order of the 1/3} B ″ _2/3 ) O ₃ powder was measured.
The density of the sintered body obtained by firing was measured, the sintered body was annealed at various times, and the annealing time at which the regularity was 0.95 or more was investigated.

[0022]

[Table 1]

[0023]

A (B 'obtained by the present invention
_{The 1/3} B ″ _2/3 ) O ₃ -based composite oxide powder is fine, has very high sinterability, and B ′ and B ″ are ordered. Therefore, it is possible to easily and densely sinter at a low firing temperature, and the annealing time for ordering is shortened.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Nagai 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Nippon Steel Corporation Advanced Technology Research Laboratories

Claims (2)

[Claims] 1. A (B ') is obtained by hydrolyzing a metal alkoxide.
_In the method for producing a _1/3 B ″ _2/3 ) O ₃ -based complex oxide powder, a mixture of an alkoxide of a metal B ′ and an alkoxide of a metal B ″ or a solution of a complex alkoxide in an organic solvent is mixed with an alkoxide group of 0. A (B ′ _1/3 B ″ _{2 /} characterized by adding 5 to 10 mole times of water, adding an alkoxide or hydroxide of metal A to the obtained hydrolysis product, and further hydrolyzing ₃ ) A method for producing an O ₃ -based composite oxide. 2. The B'alkoxide is Mg, Co, Ni, Z.
Alkoxides of at least one element selected from n, Ca, alkoxides of B ″ alkoxide of at least one element selected from Ta, Nb, Sb and A alkoxides of Ba, Sr, Ca The method for producing an A (B ′ _1/3 B ″ _2/3 ) O ₃ -based composite oxide according to claim 1, which is an alkoxide of at least one element selected from the group consisting of: