JPH013019A - Method for producing perovskite ceramic fine powder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the production of perovskite ceramic fine powder by a so-called wet method in which a precipitate is formed from a shiulic acid solution containing Ti and an acetic acid solution containing other metal elements. Regarding the method.

[Conventional technology]

Perovskite ceramics are generally referred to as ABO, and their powders are used as raw materials for electrical components such as ferroelectrics and piezoelectrics. For example, Pb (Zr
, Ti)03-based perovskite-type in-place ceramics are known to have particularly high piezoelectric properties, but in order to further improve the dielectric constant and piezoelectric properties, certain metal elements such as Sr, Ba, Nb, etc. Ta, Mg
, Pe, Mn, Co, Ni, and the like are often used by adding one or more of them.

Many methods have been developed to produce these perovskite ceramic powders, including dry methods, wet methods, and a combination of the two methods.
94 [5:] p. 11823, 1986) and its improved method (Japanese Patent Application Laid-Open No. 61-251519) have been proposed.

These conventional methods require that oxalic acid is soluble in ethanol and impropatul, and that Pb and Zr.

It was developed based on the fact that each oxalate of Ti is poorly soluble in alcohol. Specifically, an oxalic acid alcohol solution obtained by dissolving shialic acid in alcohol and P
b, Zr, and Ti ions are mixed with a nitric acid solution to form a precipitate consisting of a complex oxalate,
In this method, the obtained precipitate is washed with alcohol, filtered, dried, and ground, followed by calcining (thermal decomposition) in air at 500 to 1100°C.

[Problem that the invention seeks to solve]

In the conventional method, composite oxalate is produced and precipitated in a solution containing nitrate radicals, so that the nitrate radicals are adsorbed on the particle surface of the composite oxalate. Since the generated complex oxalate has a very high surface activity, the adsorbed nitrate radicals cannot be sufficiently removed even by washing with water or alcohol. Therefore, the composite oxalate is dried while adsorbing nitrate radicals and calcined in a calcining furnace.

Therefore, at the temperature during calcination, nitrate radicals decompose freely and become gasified into nitrogen oxides, which corrode the furnace walls and reduce their durability.Also, the nitrogen oxide gas discharged from the furnace is harmful to the environment. There were several operational problems, including deterioration.

[Means for solving problems]

The present inventors conducted research on a wet method capable of producing a composite oxalate precipitate using a compound that does not contain nitrogen, and as a result, completed the invention as described below.

That is, one of the aspects of the present invention has the general formula ABO3 (where A is one or more of oxygen 12-coordination metal elements such as Pb, Sr, La, Ba, etc., and B is a system consisting of two or more metal elements). , one is Ti, the other is oxygen 6 such as Zr, Mg, Fe, etc.
Indicates one or more types selected from coordination metal elements. ) When producing a fine perovskite ceramic powder represented by This is a method for producing perovskite-type ceramic fine powder, in which a precipitate is produced by mixing an acetic acid aqueous solution (hereinafter referred to as "solution (■)") containing acetic acid, and the precipitate is dried and calcined. Another invention is that Nb2O is used in the manufacturing process.

The gist of the present invention is a method for producing perovskite-type ceramic fine powder by adding powder of Ta20I and/or Ta20I.

Hereinafter, the invention will be explained in detail in order from the first invention of Katsunari Hon.

The raw materials used in the first invention are shiulic acid, alcohol, titanium alkoxide, a compound that also contains component A, and B excluding Ti.
the component compound and acetic acid or acetate.

Commercially available oxalic acid, alcohol and titanium alkoxide are usually used.

Alcohols include ethanol, methanol, n-propatol, 1so-propatol, n-butanol, and the like, but are not particularly limited, but preferably contain an alcohol content of 3Qvo 1% or more and water of 10vo 1% or more. Considering economy, methanol is preferable because it is inexpensive.

Oxalic acid may be used in either anhydride or dihydrate form. The titanium alkoxide is preferably titanium tetrane propoxide, but is not particularly limited as long as it is an alkoxide that is soluble in a sialic acid alcohol solution.

As the compound containing component A and the compound containing component B other than T1, those that do not contain nitrogen and are soluble in acetic acid, such as acetates, carbonates, and hydroxides, are used.

Next, a method for preparing solution (1) using oxalic acid, alcohol, and titanium alkoxide will be described.

The method of dissolving oxalic acid in alcohol and the method of dissolving titanium alkoxide in the obtained oxalic acid alcohol solution to prepare a solution (D) are both carried out by conventional methods.

The amount of oxalic acid to be used varies depending on the type and amount of the compound used, but it is not particularly limited as long as it is more than the order of magnitude necessary to precipitate a complex oxalate. The amount of alcohol used may be an order of magnitude or more sufficient to completely dissolve oxalic acid.

The method for preparing solution (II) from each compound containing component A and component B other than Ti is to dissolve the compound in water if it is an acetate, or to dissolve it in water if it is a carbonate or hydroxide. Dissolve in acetic acid aqueous solution. All the methods of dissolution are carried out by conventional methods.

Dissolved amount of each compound of component A and component B other than Ti and solutions (1) and (II) when preparing the above solution (n)
The mixing amount must be such that the metal elements contained in the ultimately obtained perovskite fine powder are dissolved in a desired composition ratio, but the composition ratio is not particularly limited in the present invention.

To mix solutions 1 (1) and (II), simply add one solution while stirring the other, and as a result, oxalate containing each metal element is generated and mixed as a composite oxalate. co-precipitate in a state where

The obtained precipitate was filtered, dried, and then immersed in air at 400 °C.
By calcining at a temperature of 1100°C to 1100°C, preferably 500 to 900°C, a perovskite ceramic fine powder with a submicron particle size can be obtained.

The second invention of the present invention is a method of manufacturing a multi-component perovskite type ceramic fine powder by adding powders of Nb2O and/or T a and O in the manufacturing process of the first invention.

Commercially available Nb, O, and Ta, O, are used.

These compounds may be added at any step before the calcination step of the first invention. For example, solution (1) and solution (
It), solution (r) and solution (II)
) may be added at any stage, such as during the mixing process, into the suspension after mixing, or into the dried precipitate. The addition is Nb
, O, and/yet Ta, O.

The same effect can be obtained even if the powder is divided into two parts and each part is added at an appropriate stage. It is preferable to add the ingredients as early as possible to ensure sufficient mixing.

Only one of Nb2O6 and Ta205 may be added, or both compounds may be added. The amount added is not particularly limited in the present invention.

The fineness of Nb, O, and Ta, O is preferably as fine as possible in order to disperse it uniformly. In particular, when added to a suspension, it is desirable that the average particle size be 3 μm or less, since sedimentation and separation from sediment will not occur.

The present invention will be explained below with reference to Examples.

[Example 1] Pb (Ti, Zr) 03 was produced as follows.

Oxalic acid (trihydrate) 140? Titanium tetrane propoxide (Ti concentration 3
．． 323 mol/1)72.2- was added in the form of a mist to form a clear solution (I).

On the other hand, zirconyl acetate (Zr concentration, 1.458 mol/l
) was added with 300% pure water, and then, with stirring, lead acetate (
trihydrate) 189,7 f (0.5 mol in terms of PbO)
was added and dissolved to form a clear solution (n).

While stirring the solution (1), the solution (II) was added in the form of a mist to form a precipitate, and the precipitate was separated by suction filtration (P paper 5C). After drying this precipitate at 70°C for 24 hours,
It was calcined in an electric furnace at 600°C in the air for 1 hour.

The fineness of this fine powder and the minerals produced were examined using an automatic sedimentation particle size analyzer and an X-ray diffractometer, and it was found to be a single mineral perovskite type ceramic fine powder with an average particle size of 0.3 μm.

[Example 2] (Pb, La) (Ti, Zr, Mg) 0. A perovskite-type ceramic fine powder consisting of the following was produced as follows.

Oxalic acid dihydrate 126. (l is methanol (99,9v
titanium tetraisopropoxide (Ti concentration 3.32
52.7 ml of 3 mol/1) was added in the form of a mist, and 500 mL of pure water was further added to prepare a transparent solution (1).

On the other hand, solution (II) was prepared as follows. That is, zirconyl acetate (Zr concentration 1.458 mol/1)22
Add 400 m of pure water to 2.9 m/m, and add m of acetic acid while stirring.
Trihydrate salt 174.59 (PbO equivalent: 0.46-E)
Add 50% of pure water to 50% of acetic acid, and add 50% of La2O3 powder and MgCO3 while stirring.
A transparent solution (II) was prepared by mixing with a solution in which powder 1.79 (MgO equivalent o, sr) was added and dissolved.

Next, while stirring the solution (1), the solution (n) was added in the form of a mist to form a precipitate, and the precipitate was separated by suction filtration.

The obtained precipitate was dried at 70 tons for 24 hours, and then calcined in an electric furnace at 700° C. for 2 hours in the air.

The resulting calcined product was examined for fineness and mineral formation, and it was found to be a fine powder consisting of a single phase of tetragonal perovskite oxide with an average particle size of 0.5 μm.

[Example 3] (Pb, Sr) (Ti, Zr)03-Nb,
, 0. A perovskite solid solution was produced as follows.

Titanium tetrainopropoxide (Ti concentration 3.328%) was added to a solution of 113,4 mol (0.9 mol) of oxalic acid (dihydrate) dissolved in 1 t of methanol (containing 1 Ovol % of water) with stirring. A clear solution (1) was prepared by adding 70.7 ml of mol/1) in the form of a mist.

Meanwhile, 18 lead acetate (trihydrate) in 500 rnl of ion-exchanged water
0.17 y (0.475 mol in terms of PbO) and strontium acetate (salt) 5,37 ? (0.025 mol in terms of SrO) was dissolved with stirring, and then zyl acetate/L was added to the aqueous solution (Zr concentration 1.458 mol/L).
181.7- was added to prepare solution (n).

While stirring solution (1), solution (II) was added in the form of a mist to form a precipitate, and further 1.72 niobium pentoxide powder with an average particle size of 0.8 μm was suspended, and the mixture was thoroughly stirred for - hours.
Thereafter, the precipitate was separated by suction filtration (P paper 5C). After drying this precipitate at 70°C for 24 hours, it was
It was calcined in an electric furnace at ℃ for 1 hour.

The fineness of this fine powder and the minerals produced were investigated using an automatic sedimentation particle size analyzer and an X-ray diffractometer. , Nb2O, etc. were not present.

〔Effect of the invention〕

Since the present invention does not use any nitrates used in conventional methods, there is no need to wash the precipitate, and no nitrogen oxides are generated during the calcination/calcination process, which solves various problems related to furnace maintenance and the environment. Furthermore, Ta, which was impossible with conventional methods,
It becomes possible to add elements such as Nb that are difficult to dissolve into solution, and it can be applied to the production of many types of perovskite ceramic fine powders.

Patent applicant: Nippon Cement Co., Ltd.

Claims (2)

[Claims] (1) General formula ABO_3 (However, A consists of one or more kinds of oxygen 12-coordination metal elements such as Pb, Sr, La, Ba, etc., and B consists of two or more kinds of metal elements, one of which is Ti, Others indicate one or more selected from oxygen six-coordination metal elements such as Zr, Mg, Fe, etc.) When producing perovskite type ceramic fine powder represented by and an acetic acid aqueous solution containing metallic elements of component A and component B other than Ti to form a precipitate, and then the precipitate is dried and calcined. Production method. (2) In the method for producing perovskite ceramic fine powder according to claim (1), powdered N
A method for producing perovskite-type ceramic fine powder, characterized by adding b_2O_5 and/or Ta_2O_5.