JPS61106456A - Manufacturing method of high-density PZT piezoelectric ceramics - 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 Public Fund The present invention relates to a method for manufacturing high-density PZT-based piezoelectric ceramics. PZT-based piezoelectric ceramics is a fill.PZT-based piezoelectric ceramics referred to in the present invention has the general formula Pb (
Zrx-Ti, -x)03 (where x = 0.1
~0.9), and the molar ratio of Pb / (Zr + Ti) in the above formula is higher than 1.0. Conventional methods for producing raw material powder for PZT ceramics include the dry method and A wet coprecipitation method is known.

The dry method is a method in which the constituent compound powders are mixed and calcined. However, with this method, it is difficult to obtain a raw material powder with a uniform composition, and it is necessary to increase the calcination temperature to complete the PZT production reaction, which causes the particles to become coarser, making it difficult to sinter. There were some drawbacks that made it difficult to overcome.

Because of the uniformity of the particles, they tend to coagulate during precipitation, drying, and calcination to form secondary particles, making them easy to sinter and difficult to disintegrate. Furthermore, in the coprecipitation method, the concentration of the precipitate-forming liquid when added is constant, so if the precipitate-forming ability of each component differs, for example, one component will generate 100% precipitate, while another component will generate 100% precipitate. % precipitate may be formed, which may cause a layer to form, making it difficult to obtain a desired composition. Furthermore, since PZT contains lead and titanium, when co-precipitating these,
If cheap titanium tetrachloride is used as a titanium raw material, the chlorine ions of titanium tetrachloride will react with lead ions to form a white precipitate, so titanium tetrachloride cannot be used. In this case, the formation of this precipitate can be prevented by using titanium oxynitrate instead of titanium tetrachloride, but titanium oxynitrate is expensive and therefore not practical for industrial production.

Therefore, it is an object of the present invention to provide a method for manufacturing PzT-based ceramics that is inexpensive and has excellent high density.

Structure of the Invention As a result of research to achieve the above object, the inventor of the present invention found that among the raw material components of PZT, when lead and titanium are not co-precipitated and double precipitates are formed, quartz is an inexpensive titanium raw material. Since titanium chloride is used and the process is double-operated, the concentration of the precipitate forming solution can be adjusted to conditions suitable for precipitate formation at each stage, making it possible to achieve the desired composition of precipitate components and to ensure uniform dispersion. However, since it was a double precipitation, it was found that no secondary particles were formed due to coagulation. It has been found that by using the raw material powder thus obtained, high-density PZT-based piezoelectric ceramics can be obtained without requiring high-temperature sintering. Based on this knowledge, the present invention was completed.

All the components are mixed to form a homogeneous precipitate, and the precipitate is mixed into the PZT-based ceramic of the present invention. In order to control the sinterability and properties of the PZT ceramic, trace components such as Ba are added.

Cta, Sr, Sn + Mn, Al,
La + Wb + Os + Ge + V + Y
* Bi, Fe, Or + Ni, Ir
+ Rh t Na * Sc , In , K +
Any compound such as Ga, TI, W, or Th1 may be added. In this case, it can be added uniformly by coexisting in two types of aqueous solutions. In addition, after the preparation of PZT-based powder, there is a conversion method or a wet method for formate, oxalate,
Examples include chlorides and oxides. If these are not soluble in water, mineral acids can be added to make them soluble.

Examples of the precipitate-forming liquid include solutions of ammonia, ammonium carbonate, caustic alkali, soda carbonate, citric acid, soybean ammonium, and organic reagents such as d-oxine and amines. You can choose from these.

In order to generate precipitation of the constituent components, it is preferable to perform the precipitation while stirring the liquid.

Further, after the formation of a certain precipitate, the filtrate may be removed, and the type and concentration of the precipitate forming liquid may be changed to those suitable for the remaining components, and the precipitate may be precipitated.

If an alcohol such as ethanol is used to wash the precipitate, good results can be obtained since coagulation of the precipitate is suppressed in the subsequent drying and calcination steps.

PZT-based rice powder is produced.

Next, it is shaped and sintered. Although it is industrially advantageous to perform sintering in air, sinterability can be increased by performing sintering in an oxygen atmosphere. In this case, if a perovskite compound containing lead, such as a perovskite compound, is allowed to coexist during the closure to allow oxygen and air to pass through, and lead vapor is included in the atmosphere, scattering of lead during sintering can be suppressed. can.

If the sintering temperature is lower than 850°C, sintering will be insufficient.
If the temperature exceeds 1280°C, the structure becomes porous with significant lead scattering, so the temperature should be 850 to 1280°C. It is necessary.

An aqueous solution containing Example Titanium 9.106f was added dropwise to obtain a homogeneous precipitate of lead, zirconium, and titanium hydroxides. After washing and drying the precipitate, it was calcined at 700'C for 1 hour to obtain a raw material powder having a composition of Pb(Zro, .Ti0.421)03. When this powder was observed with a scanning electron microscope, it had a uniform particle size of about 0.25 μm, and when the composition variation was measured by X-ray diffraction, almost no variation was observed.

The powder was molded at 1.5t/C- and sintered at 1200°C for 2 hours in a lead vapor and oxygen atmosphere. As a result, a dense sintered PZT body having a theoretical density (8.0) was obtained.

Comparative Example Commercially available powders of PbO, TiO2, ZrO2 were mixed with Pb(Z
r0. s2'Ti0.48)05, mixed in a ball mill, calcined at 800°C for about 2 hours, and heated again with oxygen gas and lead vapor at 200°C for 2 hours. Sintered in atmosphere. The density of the obtained sintered body was 7. It was a process.

Effect of the invention The method of the present invention has the following excellent effects.

Since lead and titanium among the raw material components of fll PZT are not co-precipitated, inexpensive titanium tetrachloride can be used as a titanium raw material.

+21 Do not coprecipitate all of the constituent components of PZT,
Due to the formation of double precipitates, these precipitates are in an interdispersed state, and there is less formation of secondary particles during drying and calcination as in conventional co-precipitation of all components. Therefore, a material with high bulk density and easy sinterability can be obtained.

Claims (1)

[Claims] General formula Pb(Zr_x・Ti_1_-_x)O_3 (where x represents 0.1 to 0.9), and P of the above formula
In the production of PZT-based piezoelectric ceramics in which the molar ratio of b/(Zr+Ti) is shifted higher or lower than 1.0, aqueous solutions of lead, zirconium, and titanium are prepared, and the zirconium aqueous solution is mixed with either the lead aqueous solution or the titanium aqueous solution. After uniformly mixing excess precipitate forming liquid into one of these aqueous solutions to form a precipitate, the aqueous solution in which this precipitate was dispersed and the remaining aqueous solution of the other type were uniformly mixed. After mixing to make a homogeneous precipitate of all the components and calcining the precipitate at 500 to 1100°C,
A method for producing high-density PZT-based piezoelectric ceramics, which comprises sintering a molded product at 850 to 1280°C in air, oxygen atmosphere, or an atmosphere containing lead vapor.