JPH0193419A - Production of piezoelectric ceramics raw material powder - Google Patents

Abstract

PURPOSE:To completely precipitate all the components and enable production of a raw material powder having a desired composition, by improving a multistage wet method in producing a raw material powder of perovskite expressed by a specific general formula and a solid solution thereof by the multistage wet method. CONSTITUTION:A raw material powder of a compound, having a composite perovskite type structure and expressed by the formula and a solid solution thereof is prepared. In the formula, A is one or more of Mg, Zn, Ni and Co; B is Nb and/or Ta; x, y and z are expressed in terms of mol.% and x+y+z=100. In the production, solutions of A, B and Zr components are brought into contact with a precipitate-forming solution or an A-B-O based compound oxide and solutions of Pb and Zr compounds are brought into contact with a precipitate-forming solution. Furthermore, anatase type TiO2 is dispersed in the liquid phase in any stage of forming precipitates to form mixed precipitates of the above-mentioned respective components, which are then calcined at 500-1,200 deg.C to provide the aimed piezoelectric ceramics raw material powder.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing raw material powders of perovskites and solid solutions thereof.

Perovskites and their solid solutions are piezoelectrics, dielectrics,
It is widely used as functional ceramics for semiconductors, sensors, optoelectronic materials, etc. Recently, there has been a desire to further improve this functionality, and raw material powders of perovskite and its solid solution that are easy to sinter, have uniformity, have high bulk density, and are low cost are available in large quantities to meet this demand. There is a need for the development of technology that allows for efficient manufacturing.

(Prior Art and its Problems) Conventionally, dry methods, coprecipitation methods, and multistage wet methods are known as methods for producing raw material powders of perovskites and solid solutions thereof.

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, it is difficult to obtain a raw material powder with a uniform composition, so it is difficult to obtain a perovskite with excellent functionality, and the sinterability is also insufficient.

The coprecipitation method is a method in which a mixed solution is prepared by combining all of the constituent components, a precipitate forming liquid such as an alkali is added to the mixed solution to cause coprecipitation, and the coprecipitate is dried and calcined.

According to this coprecipitation method, it is easy to obtain powder with excellent uniformity, but
Because of their uniformity, the particles tend to coagulate to form secondary particles during precipitate formation, drying, or calcination, making it difficult to sinter.

In addition, in the coprecipitation method, if the precipitate forming ability of each component with respect to the precipitate forming solution is not the same, for example, the components consisting of substantially 1
However, other components may only partially produce precipitates, making it difficult to obtain a desired composition.

The multi-stage wet method is disclosed in JP-A-61-53113 and JP-A-6
As described in Publication No. 1-53115, etc., the above-mentioned drawbacks of the coprecipitation method are solved by precipitating each component in stages. However, even in the multi-stage wet method, it was difficult to precipitate substantially 100% of the Mg component, Zn component, Ni component, and Co component.

(Objective of the Invention) An object of the present invention is to provide a method that improves the multi-stage wet method and can completely precipitate all the components to produce a raw material powder of perovskite and its solid solution having a desired composition. be.

Another object of the present invention is to provide a method for efficiently producing raw material powder of perovskite and its solid solution, which has excellent piezoelectric properties and satisfies the requirements of easy sinterability, uniformity, low cost, and high bulk density. It is to be.

(Means for solving the problem) The present invention has the general formula %) (where A represents at least one of Mg, Zn, Ni and Co, B represents at least one of Nb and Ta, y and 2 indicate mol%, x+y+z
=100. ) When producing the raw material powder of perovskite and its solid solution represented by (1) Pb, A,
A solution of B and Zr components is brought into contact with a precipitate forming solution, or (2) a solution of A-B-0 complex oxide and Pb, Zr components is brought into contact with a precipitate forming solution, and anatase type Ti (h A method for producing a piezoelectric ceramic raw material powder, characterized in that a mixed precipitate of each of the above components is formed by dispersing it in a liquid phase at any stage of precipitate formation, and this is calcined at 500 to 1200°C. It is related to.

In the present invention, the term "solution" refers to a solution in which soluble substances are dissolved or a suspension in which insoluble substances are dispersed.

In the present invention, the A component of the perovskite and its solid solution represented by the general formula (%) is Mg, Zn, Ni and CO (all of which are one type of the perovskite), and the B component is at least one of Nb and Ta,
Pb(A+z+Bxz+) pb and (AI/
3B! /3) component atomic ratio (Pb/ (A+zJz/
3) ), the atomic ratio of pb and Ti in PbTi0z (Pb/Ti) and pb and Zr in PbZr01
The atomic ratio (Pb/Zr) 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.

In addition, x, y and 2 in the above general formula represent mol% and can take various values depending on the use, but usually X is 5 to 90.
, y is preferably selected from the range of 5 to 80 Sz and 5 to 80 mol%. If it is outside this range, it is not preferable because it will cause problems in terms of characteristics.

A, which is a component of perovskite and its solid solution;
The component compounds for preparing a solution of B, Pb and Zr component compounds include, but are not particularly limited to, inorganic salts such as their hydroxides, carbonates, oxysalts, sulfates, nitrates, and chlorides; It is appropriately selected from organic acid salts such as acetates and oxalates, oxides, and the like. As the Tl source, anatase type Ti01 is used, and the particle size thereof is preferably small, and is preferably about 0.1 to 2 μm.

The A-B-0-based composite oxide in the present invention can be produced by: (1) a dry method in which oxides or carbonates of the A acid component and B component are mixed and calcined; (2) either one of the A acid component and the B component; A semi-wet method in which the insoluble raw material of the other component is suspended in a liquid phase, the solution of the soluble raw material of the other component is brought into contact with the precipitate forming liquid to form a mixed precipitate, and this is calcined; ■A acid component and B component It is prepared by a wet method in which a solution of soluble raw materials is brought into contact with a precipitate-forming liquid to form a mixed precipitate, which is then calcined. The calcination temperature is 50 in both cases.
A temperature of 0 to 1300°C is suitable.

Examples of the precipitate forming liquid in the present invention include solutions of ammonia, ammonium carbonate, caustic alkali, amine, oxalic acid, alkylamine, and the like.

Examples of the alkylamine include primary amines having a lower alkyl group such as methylamine, ethylamine, propylamine, and butylamine, tertiary amines having a lower alkyl group such as dimethylamine and diethylamine, and tertiary amines having a lower alkyl group such as triethylamine. Mention may be made of amines.

In order to generate 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,
On the contrary, it may be added. The addition is preferably carried out while sufficiently stirring the liquid. Further, the precipitation may be formed in one stage or in multiple stages.

Anatase type TiO□ and Pb in the present invention, A,
For contacting the precipitates of B and Zr components, TiO□ may be suspended in a precipitate forming solution in advance, or TiOz may be added and mixed after forming a precipitate. When forming a precipitate in multiple stages, TiO2 may be added in the middle.

The same applies to the case where an A-B-0 based composite oxide is used.

The mixed precipitate obtained by the above method is preferably washed with water or the like, but may not be washed depending on the starting materials. The mixed precipitate is dried and then calcined. Drying may be performed in the air or under reduced pressure. As for the calcination temperature,
If it 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.
A range of 200°C is preferred.

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

Example 1 37,5[Pb (Mg, z+Nbzz:+) 03
]-37,5PbTiO+-25,0PbZrOs 13.509 g of niobium pentachloride (NbCj!5) was dissolved in 300% of ethanol, and further 10% of 6N-ammonia aqueous solution was dissolved.
00d was added. To this, lead nitrate [Pb(NOx) z
A solution of 6.242 g of colo dissolved in 500 mN water was added. Furthermore, zirconyl chloride (ZrOCfz-8Hz
O) 16. A solution of 11g dissolved in 500ml of water was added to form a precipitate. Next, 5.99 g of anatase-type TiO□ powder with a particle size of 0.4 μm was added and thoroughly stirred.

This mixed precipitate was repeatedly decanted and washed with water four times, and the ammonium ion concentration was adjusted to 0.11 mol/l.
50 ml of an aqueous solution containing 10 d of 5N ammonia water was added to adjust the pH to 12.1. A solution of 5.141 g of magnesium hydroxide [Mg (OH) z] dispersed in 350 d of water was gradually added to this liquid to form a precipitate.

This precipitate was filtered without washing, dried, and then analyzed for composition, which revealed that the elemental composition was the same as that of the initial precipitate. Further, this precipitate was calcined at 750°C for 2 hours. Ethanol was added to this powder and it was ball milled, and part of the powder was observed using a transmission electron microscope, and the particle size was found to be 0.
It was uniform at about 5 μm.

0.8wtχ of polyvinyl alcohol was added to this calcined powder, and it was molded at it/cd and heated at 1150℃ for 2 hours in a lead atmosphere.
Sintered for hours. The density of the obtained sintered body is 7.97 g/c
It was Ta. This sintered body is 10gmφX 1 trm
After polishing to the size of t, apply silver paste and
An electrode was formed by baking at 0''C.This sample was
An electric field of 20 KV/cm was applied to conduct polarization treatment in silicone oil at 00°C. When the piezoelectric properties were measured at room temperature using an impedance analyzer, the electromechanical coupling coefficient (Kp) was 70%, and the piezoelectric constant (d2+) was 210X1.
0-''m/V and relative permittivity (ε, 3/ε.) of 2,100.

Comparative Example 1 37,5[Pb (Mg 1zsNb zy3) Ox
]-37,5PbT 1os-25,0PbZr03
Niobium oxide (Nbzo3) 33.5g, lead oxide (PbO
) 223.2g, anatase type titanium oxide (TiOz)
30.0g - 30.8g of zirconium oxide (ZrO□)
and 5.1 g of magnesium oxide (MgO),
After sowing and mixing, it was dried.

This product was calcined at 750°C for 2 hours. The particle size of the obtained powder was 1 to 2 μm and was irregular.

Further, when this powder was sintered in the same manner as in Example 1, the density of the obtained sintered body was 7.30 g/cffl. Piezoelectric properties are Kp45%, d3IIIOXIO-”
m/V, ε1. /ε. It was 950.

Comparative Example 2 A calcined powder was obtained in the same manner as in Example 1 except that rutile titanium oxide was used instead of anatase titanium oxide. The particle size of the obtained powder was 1.5 μm. When this powder was sintered in the same manner as in Example 1, the density of the obtained sintered body was 7.90 g/cffl. Piezoelectric properties are K153%, dH140XlO-
”m/V, εss/εo was 1300 te.

Example 2 12 [Pb (Mg I /9N i zzJb z
ys＞Os]-44PbT 1oz-44PbZr
Os magnesium oxide (MgO) 1.07g, nickel oxide (NiO) 3.98g-, niobium pentoxide (NbzO)
3) 21.26 g was weighed, a small amount of water was added, the mixture was thoroughly mixed, and then dried. This product was calcined at 1000°C for 3 hours to obtain a powder of Mg-Ni-Nb-0 based composite oxide. 2.63g of this composite oxide and 7.03g of anatase type titanium oxide (TiO□) were mixed in 300IR of 4N ammonia water.
1 and dispersed and suspended.

In this, 66.24 g of lead nitrate [Pb(NO3) z],
Zirconyl nitrate [Zr0(NO3) t・2HtO]2
A solution of 3.52 g dissolved in 300 d of water was added to form a precipitate. This mixed precipitate was repeatedly decanted three times with 1000 d of water, washed, dried, and calcined at 800° C. for 2 hours. The particle size of the obtained powder was 0.6 μm.

Further, when this powder was sintered at 1100°C, the density of the obtained sintered body was 7.92 g/cj. The piezoelectric properties are Kp60%, d31290X10-1gm/V, ε
There was +s/εo 3200te.

(Effect of the invention) General formula x[Pb(A+z,Bz/+)O+]-y(Pb
TiO3)-z(PbZrO3) (where A is Mg5
At least one of Zn-, Ns and Co is shown, B is at least one of Nb and Ta, x, y and 2 are mol%, and x+y+z=100. ) When producing the raw material powder of perovskite and its solid solution represented by By bringing the oxide into contact with precipitates of other components, followed by drying and calcining, it is possible to produce piezoelectric ceramic raw material powder with excellent piezoelectric properties, high bulk density, and easy sinterability with good reproducibility. .

In addition, in this process, each phase is highly mutually dispersed,
Therefore, a calcined product of this material achieves sufficient uniformity. Further, since the process is simple, it has excellent effects such as being able to obtain easily sinterable powder with good reproducibility and at low cost.

Patent applicant: Ube Industries Co., Ltd.

Claims (1)

[Claims] General formula x[Pb(A_1_/_3B_2_/_3)O
_3]-y(PbTiO_3)-z(PbZrO_3)
(However, A represents at least one of Mg, Zn, Ni, and Co, B represents at least one of Nb and Ta, x, y, and z represent mol%, and x+y+z=1
It is 00. ) When producing the raw material powder of the composite perovskite structure compound (hereinafter referred to as perovskite) and its solid solution, (1) Pb, A, B and Zr
Either a solution of the components is brought into contact with a precipitate-forming solution, or (2) a solution of the A-B-O complex oxide and Pb, Zr components is brought into contact with a precipitate-forming solution, and anatase-type TiO_2 is brought into contact with a precipitate-forming solution. A method for producing a piezoelectric ceramic raw material powder, which comprises dispersing the components in a liquid phase in the above step to form a mixed precipitate of the components, and calcining the precipitate at 500 to 1200°C.