JPS62162670A - Manufacture of lead zirconate titanate sintered body - 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 [Field of Industrial Application] The present invention relates to a method for producing a sintered body of lead zirconate titanate (hereinafter referred to as "PZT").

[Conventional technology]

PZT sintered bodies are widely used as excellent piezoelectric and pyroelectric materials.

Conventionally, methods for manufacturing PZT sintered bodies include lead (pb),
A method has been used in which zirconium (Zr) and titanium (Ti) oxides are dry mixed in the required proportions and sintered in air containing PbO vapor, but in recent years, alkoxides of these component metals have been sintered. A method has been used in which a fine powder consisting of composite precipitates is obtained by simultaneous hydrolysis in the same solution (hereinafter, the manufacturing method of this fine powder is referred to as the "alkoxide method"), and the fine powder is sintered. It's here.

That is, the fine powder obtained by the alkoxide method used in the latter production method is considered to be an oxide or hydroxide of Pb, Zr, and Ti, or a hydrate thereof.
It has attracted attention because it has excellent sinterability because it is made of fine particles with high purity and high uniformity, and it can be sintered at a lower temperature.

[Problem that the invention seeks to solve]

By the way, in manufacturing laminated elements such as piezoelectric actuators, forming pyroelectric films, etc., a coating film is formed by a screen printing method and then sintered to produce a PZT sintered body film. At this time, if the firing temperature is high, there is a risk that the inner membrane may be deformed, and if the electrodes are fired at the same time, even expensive gold electrodes may be destroyed. However, it is desirable that firing can be carried out at as low a temperature as possible, preferably at a temperature of 1000° C. or lower, since this may cause problems such as failure and failure to apply electrodes. However, even with the alkoxide method described above, it is currently not possible to obtain a fine powder that can be sufficiently sintered at 1000° C. or lower.

A known method for lowering the sintering temperature when producing a PZT sintered body is to add an excessive amount of PbO when dry mixing oxide powders of Pb, Zr, and Ti, and then sinter the powder. (Osamu Yamaguchi, Powder and Powder Metallurgy, 17.
3.116-121 (I970)), but in the Kono method, a large precipitated phase of PbO appears in the sintered body, and a uniform PZ
No T sintered body was obtained.

Furthermore, in the conventional method for producing a PZT sintered body, pb.

Another drawback was that the work was complicated because it required sintering in air containing steam.

Therefore, the purpose of the present invention is to solve these problems and to
By sintering at a low temperature of 000℃ or less, uniform and high-density P is produced.
An object of the present invention is to provide a method for producing a PZT sintered body that can produce a ZT sintered body.

[Means for solving problems]

The present invention is intended to solve the problems of the prior art described above.

A general formula (+) consisting of adding water to a solution containing titanium alkoxide, zirconium alkoxide and lead alkoxide, and calcining the fine powder obtained by hydrolyzing these alkoxides, molding and sintering the fine powder: PbxZrATll-A03”・(I
) [In the formula, A is 0.1≦A≦0.98] In the method for producing a lead zirconate titanate sintered body, X in the general formula (I) is 1. 01≦x≦1.2
0, and provides a manufacturing method characterized in that the powder is sintered at a temperature of 800°C or higher.

The present invention provides fine powder with high sinterability by adjusting the lead component to be in excess of the stoichiometric amount when producing fine powder for sintering using the alkoxide method described above. is used for sintering.

The alkoxide method is, for example, as described in Japanese Patent Application Laid-Open No. 57-82121, and PZT of a desired composition is
In other words, in accordance with the above general formula (Pb:Zr:Ti (molar ratio) = x
:A: 1-A This is a method of obtaining a fine powder as a precipitate by dissolving three types of alkoxides, Pb, Zr and Ti, in a suitable solvent, adding water and simultaneously hydrolyzing them so that the alkoxides are as follows: A: 1-A. The solvents that can be used are not particularly limited as long as they are good solvents for the three metal alkoxides used, and examples include benzene, toluene, xylene, hexane, methyl ether, ethyl ether, methyl alcohol, ethyl alcohol, propyl alcohol, Examples include isopropyl alcohol. This alkoxide method can be carried out in various ways. For example, as described in JP-A-57-82121, a solution of alkoxides of three metals may be mixed and drained in required amounts, or as described below. As in the example, first, Ti and Zr alkoxides were added to a solution prepared from sodium alkoxide, then lead acetate was added and reacted to produce lead alkoxide in the solution, and water was added to this. Yes, there are no particular restrictions.

Pb, which can be used as a raw material in the alkoxide method
, Ti and Zr alkoxides include, for example,
Examples include isopropoxide, methoxide, ethoxide, rhopropoxide, n-butoxide, tart-butoxide, etc., which can be easily synthesized by the method described in the above publication, and some are commercially available. .

The fine powder obtained by the alkoxide method is Pb.

They are considered to be composite particles made of oxides, hydroxides, or hydrates of Ti and Zr, but they are highly pure and consist of uniform fine particles.

This fine powder is filtered, washed, dried, calcined, preferably pulverized, molded, and further subjected to sintering.

The fine powder obtained as described above contains Pb, Zr and Ti in proportions corresponding to general formula (I),
x=1. It is necessary that lead be in the range of O1 to 1.20 and contain lead in excess of the stoichiometric fi (x=1). When X is less than 1.01, sintering at a temperature of 1000° C. or lower is difficult, and a high-density sintered body cannot be obtained. Moreover, if X is larger than 1.20, a precipitated phase of lead oxide is generated in the sintered body, making it impossible to obtain a uniform sintered body.

The above-mentioned fine powder obtained by the alkoxide method is calcined, preferably pulverized, then shaped and subjected to sintering. The calcination temperature of the fine powder is preferably 500 to 800°C, particularly 600°C.
~700°C is preferred. If the calcination temperature is less than 500°C, the solid phase reaction will not be completed and a high-density sintered body will often not be obtained by subsequent sintering, and if it is higher than 800°C, the grain growth of the fine powder will increase. , it is difficult to obtain high-density sintered bodies.

Further, the sintering temperature needs to be 800°C or higher, preferably 900°C to 1200°C. In particular, x=1.01
-1.05, preferably 900°C or higher.

If the sintering temperature is less than 800°C, sintering will not proceed much. If the sintering temperature exceeds 1200°C, the evaporation of PbO will become intense, which is not preferable for obtaining a high-density sintered body.

The 8 g of air used in performing the above sintering may be air containing PbO vapor as in the past, but plain air containing no PbO vapor is also sufficient.

[For production]

In the fine particles subjected to sintering in the present invention, it is thought that excess lead oxide is uniformly dispersed in Zr and Ti oxides to form a composite. It is presumed that liquid phase sintering progresses rapidly and uniformly at low temperatures to wet the surface or grain boundaries of the reaction components, resulting in a highly dense and uniform sintered body.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 (I) Zr/Ti=52/48 (corresponding to A=0.52 in general formula (T)) and various pb contents (x
= range of 0.93 to 1.25) PZT sintered body samples 1 to 30 were manufactured by the method of the invention. Sample Nα
The production of the PZT sintered body of No. 8 will be exemplified.

(2) Production of PZT sintered body of sample &8: 12.852 g of metallic sodium and 150 g of isopropyl alcohol
Q was reacted with sodium isopropoxide to produce sodium isopropoxide. To this, Zr:Ti=52:48 (molar ratio)
Titanium isopropoxide 36.028
g and 44.980 g of zirconium isopropoxide were added, and the mixture was reacted under reflux for 1 hour.

Add 90.897 g of anhydrous lead acetate (m corresponding to X = 1.06 in general formula (+)) to the obtained reaction solution,
The reaction was further continued under reflux for 1 hour. After filtering off the sodium acetate produced from the reaction solution, water was added to the filtrate to hydrolyze the alkoxide. The obtained precipitate was filtered, washed, and dried to obtain a fine powder. The obtained fine powder was heated to 600℃
After calcining for 1 hour, crush it with a crusher to produce 2t/c+a”
It was molded into a tablet under the same pressure. Pb this tablet
1 atm oxygen atmosphere saturated with O vapor (PbO vapor pressure:
A PZT sintered body was obtained by firing at 1000° C. in a temperature of about 3.4 Torr. This sintered body had a uniform and dense structure throughout, and when the sintered density was measured, it was found to be 7.
It was found that the sintered body had a high density of 92 g/- (theoretical density of 8 g/c+d), and a uniform high-density sintered body without abnormal grain growth was obtained.

(3) General formula (r) for manufacturing PZT sintered bodies for other sample rods
PZT sintering was carried out in the same manner as in the case of sample Nα8, except that the amount of lead acetate anhydride used was changed so that X in A body was produced. Table 1 shows the sintered density of the obtained sintered body. No abnormal grain growth was observed in any of the samples and they were uniform.

Table 1 (Table 1 continued) Example 2 Sample Nu31-45 (7) Production of PZT sintered body:
In this example, sintering was performed in an air atmosphere.

Other details were the same as in the case of sample Na8, except that the amount of lead acetate anhydride used was changed so that X in general formula (I) was the value shown in Table 2, and the sintering was performed at the temperatures shown in Table 2. A PZT sintered body was produced. Table 2 shows the sintered density measured for the obtained sintered body. No abnormal grain growth was observed in any of the sintered bodies of sample Nα, and the sintered bodies were uniform.

Table 2 (Continued from Table 2) [Effects of the Invention] The manufacturing method of the present invention produces a uniform PZ with a high density almost equal to the theoretical density by sintering at a low temperature of 1000°C or less.
A T sintered body can be manufactured. Therefore, it is suitable for manufacturing a PZT sintered body film using the screen printing method, which has been difficult in the past. Furthermore, it is advantageous in terms of energy saving, so it can be widely used in various applications.

The manufacturing method of the present invention allows sintering in a simple air atmosphere that does not contain PbO, and has the advantage of simplifying the manufacturing process.

Claims (1)

[Claims] 1) Water is added to a solution containing titanium alkoxide, zirconium alkoxide, and lead alkoxide, and the fine powder obtained by hydrolyzing these alkoxides is calcined, and the fine powder is molded and then sintered. General formula (I): Pb_xZr_ATi_1_-_AO_3...(I)
[In the formula, A is 0.1≦A≦0.98] In the method for manufacturing a lead zirconate titanate sintered body having a composition represented by the formula, x in the general formula (I) is 1.01. ≦x≦1.2
0, and the manufacturing method is characterized in that the powder is sintered at a temperature of 800°C or higher.