JPS62143825A - Production of composite perovskite type compound - Google Patents

Abstract

PURPOSE:To produce the titled compound at a lower temperature than in a conventional process, by mixing or dispersing a specific compound in a Ta alkoxide-containing solution or Ta alkoxide, hydrolyzing the Ta alkoxide into a gel form and heat-treating the resultant gel. CONSTITUTION:An oxide, hydroxide, salt or organometallic compound containing Ba and Zn is dispersed or mixed with a Ta alkoxide solution in an organic solvent containing >=1wt% Ta, e.g. solution of Ta ethoxide in ethanol, etc., or Ta alkoxide to hydrolyze the Ta alkoxide into a gel form, which is then heat-treated. Since the Ba and Zn in a well mixed state are fixed in the gel, a mixing state of the raw material is better than in a conventional process and Ta is converted into fine particulate and highly reactive oxide or hydroxide. Thereby the aimed composite perovskite type compound can be produced at a heat-treating temperature >=150 deg.C or more lower than in a conventional solid- phase process without contamination of impurities by abrasion of balls, etc., in a ball mill mixing method.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a composite perovskite compound Ba (Z
The present invention relates to a method for producing ntzaTa2z3)Oa.

Conventional technology In recent years, microwave band communication systems such as satellite broadcasting, satellite communications, car phones, and mobile phones have developed significantly, and as a result, the performance and cost of circuits and components used in the microwave band have improved and become lower. is being measured.

One example is a small, low-cost, and highly reliable band-pass filter or stabilized oscillator that uses a resonator made of dielectric ceramic. Dielectric ceramics used in such microwave band oscillators are required to have a high dielectric constant, a small temperature coefficient of permittivity, and a large Q value in the microwave band. (Here, Q is defined as the reciprocal of dielectric loss.) In order to meet this requirement, BaO-TiO2 system (Japanese Patent Publication No. 57-23365), SnO2-ZrO2-Ti
O2 system (Japanese Patent Publication No. 54-35678), BaO-Z
nO-Nb2O5-Ta2O5 system (Special Publication No. 59-484
83, No. 59-48484, No. 59-23044) have been developed.

Among these, complex herovskite-type compounds, Ba
Porcelain whose main composition is (Zn1t3Ta2t3)03 is
It has a high dielectric constant, a small temperature coefficient of dielectric constant, and a high Q.
It has excellent properties.

Problems to be Solved by the Invention However, this material cannot be used in conventional oxides, hydroxides,
In the so-called solid-phase reaction method, in which carbonates, etc. are mixed and then synthesized by heat treatment, the raw materials are mixed in a poor state (in order to form a complete perovskite single phase, heat treatment at a temperature of around 1100°C is required). something was necessary.

Means for solving the friend problem Dispersing or mixing an oxide, hydroxide, salt, or organometallic compound containing Ba and Zn in an organic solvent solution of Ta alkoxide or Ta alkoxide containing 1% by weight or more of Ta. This is hydrolyzed to form a gel, and this gel is heat-treated to form a composite perovskite compound Ba<Zn1t3Ta2t3)0
3 is manufactured.

Effect According to the above method, Ba and Zn are fixed in a well-mixed state in the nozzles generated by hydrolysis of Ta alkoxide, so that the mixing state is good and the heat treatment is low. Composite perovskite-type compounds are synthesized at high temperatures.

Example As a result of examining the dielectric properties of a composite perovskite compound, Ba (Znl, 5Ta2+3)03 porcelain, using various raw materials, the inventors found that the mixing state of the raw materials has the greatest effect on dielectric loss. I found it. In this regard, conventional methods have been made by mechanically mixing the main constituent carbonate and oxide powders using a ball mill, etc., and there is a limit to the degree of mixing of each component.
For this reason, the heat treatment temperature required to generate the perovskite phase has also become high.

Therefore, in the present invention, we focused on the fact that when Ta alkoxide is hydrolyzed at a concentration higher than a certain concentration, it easily gels, and by utilizing this gelation phenomenon, the mixing degree of each component element of Ba, Zn, and Ta can be adjusted. Synthesize a powder with good reactivity,
By heat-treating this, a composite perovskite compound, Ba (Zn1t3Ta2t3>
C) attempts to synthesize +.

In the present invention, Ba and Zn are fixed in a well-mixed state in the gel produced by the hydrolysis of Ta alkoxide, so the mixing state of the raw materials is much better than in the conventional method, and the Ta The resulting oxide or hydroxide has fine particles and good reactivity, and furthermore, there is no problem of contamination with impurities due to Jfl wear of the cobblestones in the ball mill mixing method. Therefore, in this method, the composite belobusnolite type compound, Ba<ZnHsTa2ts)03, can be prepared at a lower heat treatment temperature.
can be synthesized.

Examples are shown below.

Example I Ta ethoxide was weighed and dissolved in ethanol to give a concentration of 0.5 weight percent Ta, 1 weight percent, and 5 weight percent Ta. In each of these solutions, particle size 0.5 μrn1 dullness 99.5”6
Ba:Zn:Ta=3:
It was dispersed at a ratio of 1:2. This dispersion solution is
While heating to 60° C. and stirring, a 1:1 mixed solution of water and ethanol was added in an amount three times the amount of water required for hydrolysis of Ta ethoxide, and the mixture was reacted. In the case of a solution with a Ta concentration of 5 weight percent, the solution completely became a gel 5 minutes after the start of the reaction, and in the case of a solution with a Ta concentration of 1 weight percent, 50 minutes after the start of the reaction. However, in the case of a solution with a concentration of 0.5 weight percent, gelation did not occur even after 4 hours from the start of the reaction. These samples were dried at 110°C to form a powder. For comparison, the same barium carbonate and zinc oxide as used in the above reaction, average particle size 0.5 μm, purity 9
9.5'? A product prepared by mixing tantalum pentoxide (i) in a ball mill for 24 hours and drying at 110°C was also prepared.

When these 4111 ff powders were heat-treated,
Solutions with concentrations of 1 and 5 weight percent resulted in a perovskite single phase at 870°C. On the other hand, when using a solution with a concentration of 0.5% by weight, it takes 990% to form a perovsky F single phase.
It was necessary to raise the temperature to 1030°C for those using tantalum pentoxide.

Example 2 Ta butoxide was weighed in the same manner as in Example 1, and dissolved in isopropyl alcohol to obtain a solution having a Ta concentration of 3% by weight. Ba:Zn:
The ratio was set to Ta-3=1:2. . While heating this dispersion solution to 70°C and stirring, a 1:1 mixed solution of water/ethanol was added at a constant rate until the amount of water became three times the amount required for hydrolysis of TaXBa bialkoxyto, and the mixture was reacted. I let it happen. Fifteen minutes after the start of the reaction, the solution became completely gel-like with no fluidity. This gel was dried at 110°C, and Example 1
When heat treated in the same manner as above, it became a perovskite single phase at 840°C.

In the above examples, Ta alkoxides are ethoxide and butoxide, but any alkoxide may be used as long as it becomes a solution and hydrolyzes to form a gel. do not have. In addition, any Ba and Zn sources can be used as long as they produce Bad and ZnO when fired, and the present invention is more effective than using solid-phase raw materials such as tantalum pentoxide. It shows the effectiveness.

Effects of the Invention The present invention provides Ta concentration of 2 weight percent or more.
An oxide, hydroxide, salt, or organometallic compound containing Ba and Zn is added to an organic solvent solution of alkoxide or Ta alkoxide, and the Ba:Zn:Ta ratio is approximately 3:
It is characterized by dispersing or mixing at a ratio of 1:2, hydrolyzing it to form a gel, and heat-treating this gel.Compared to the conventional solid phase method, the composite perovskite type can be produced at a temperature 150℃ or more lower. Compound Ba(Znt, 3Ta2,3
)03 is possible.

Claims (1)

[Claims] An oxide, hydroxide, salt, or organometallic compound containing Ba and Zn is dispersed or mixed in an organic solvent solution of Ta alkoxide or Ta alkoxide containing 1 weight percent or more of Ta, A method for producing a composite perovskite compound, which is characterized by hydrolyzing the compound to form a gel, and heat-treating the gel.