JPH10261823A - Manufacture of ferroelectric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make low a firing temperature, to simplify the processes in the manufacturing method of a ferroelectric and also to obtain the ferroelectric, which is dense and excellent in piezoelectric performance, by a method wherein ferroelectric particles of a specified size or smaller are used for the manufacture of the ferroelectric. SOLUTION: Powder is synthesized by firing ferroelectric particles, which are 0.01 μm or shorter in particle diameter and contain the component of Pb, at 650 deg.C, for example, by a sol-gel method. The powder synthesized by the sol-gel method has little irregularity in the mean particle diameter and is excellent in uniformity compared with the powder synthesized by a solid phase method. Therefore, in the case where a ferroelectric is formed using these fine particles, the ferroelectric is excellent in the homogeneity of a ferroelectric and the dielectric breakdown strength characteristics of the ferroelectric are enhanced. Moreover, as there is not a grinding process in the sol-gel method unlike the solid phase method, impurities are never mixed in the powder due to an stirrer or the like and the piezoelectric performance of the ferroelectric is enhanced. Moreover, as the mean particle diameter of the powder is short, the fluidity of the power is good and in the case where the powder is molded by pressing, a pressure of one ton/cm<2> or thereabouts is usually required for the molding, but the pressure can be significantly reduced. Thereby, a molding process and a firing process can be simplified and the ferroelectric, which is low in cost and is excellent in homogeneity and piezo-electricity, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a ferroelectric, and more particularly to a method of manufacturing an actuator for a recording head in a piezoelectric ink jet recording apparatus.

[0002]

2. Description of the Related Art A method for producing a ferroelectric powder by a solid phase method will be described in detail. A piezoelectric material and a ferroelectric material are referred to as a ferroelectric material in which the polarization can be reversed by an external electric field among the piezoelectric materials. Here, a typical piezoelectric material and a ferroelectric PZT ceramic (Pb (Pb ( T
i, Zr) O3). Ferroelectrics containing Pb generally have large remanent polarization, relative permittivity, and piezoelectric constant.
It is known that it has excellent piezoelectricity and ferroelectricity. In addition, the molar ratio of each element in the PZT ceramic greatly affects the piezoelectricity, and the molar ratio of each element is Pb: Z
It is known that, when r: Ti = 1: 0.53: 0.47, the permittivity, the piezoelectric constant, and the like show the maximum values. Starting materials are PbO powder, TiO2 powder and ZrO2 powder,
First, the raw material powder is weighed so as to have a desired molar ratio, an appropriate amount of a mineralizer is added, and the mixture is stirred with a ball mill or the like for several tens of hours. After degreased and dried, calcined, pulverized with a crusher or the like, passed through a sieve to remove coarse particles, and then pulverized with a ball mill for several tens of hours to obtain PZT fine powder. If the homogeneity is insufficient, mix and stir again with a ball mill or the like. The P thus obtained
The average particle size of the ZT ceramic is about several μm. Thereafter, after adding and mixing a binder and the like, the mixture is granulated and formed, and subsequently fired and processed to obtain a PZT ceramic plate. The P
By forming electrodes on the upper and lower surfaces of the ZT ceramic plate and performing polarization processing, a piezoelectric element is obtained.

[0003]

Generally, when producing ceramics by the solid phase method, there is a proportional relationship between the particle size of the starting material and the sintering temperature, and the smaller the particle size, the higher the surface activity increases. The firing temperature is reduced. P synthesized by the conventional method
When using ZT ceramic powder, the firing temperature is usually 1
It is around 200 ° C. If fired at a temperature below that,
Sintering does not proceed sufficiently and the density of the film decreases, and the piezoelectric performance becomes insufficient.

Further, the Pb element in the PZT ceramic powder is PbO, which has a melting point of 886 ° C., and is easily evaporated.
Since evaporation starts at about 50 ° C., it is usually necessary to put PbO powder together in a firing furnace and fire at a saturated vapor pressure of Pb.

It is an object of the present invention to provide a ferroelectric substance which can be sintered at a low temperature, thereby simplifying the process, and is dense and excellent in piezoelectric performance.

[0006]

In order to solve the above problems, the present invention is characterized by using ferroelectric particles having a size of 0.01 μm or less.

[0007] Ferroelectric powders are frequently produced from the solid-phase method.
A high temperature of about 200 ° C. is required, and a measure for evaporating Pb is required. In the present invention, since the firing temperature can be lowered, P
The measures for evaporating b can be omitted.

In order to improve performance by further laminating, if the internal electrode material is Pt, there is no problem. However, if a low-cost base metal material is used, the base metal material diffuses into the PZT film in the firing step, and the piezoelectric performance is reduced. Will decrease,
According to the present invention, since the firing temperature can be lowered, it is possible to form and laminate internal electrodes with a base metal material.

[0009] The powder synthesized by the sol-gel method is
Compared with the solid phase method, the dispersion of the average particle diameter is small and the uniformity is excellent. Therefore, when the fine particles are manufactured using the fine particles, the piezoelectric body is excellent in homogeneity and the withstand voltage characteristics are improved. Further, since there is no pulverizing step as in the solid phase method, no impurities are mixed by a stirrer or the like, and the piezoelectric performance can be improved.

Also, since the average particle size is very small, the fluidity is good and a pressure of about 1 ton / cm 2 is usually required for pressure molding, but this can be greatly reduced. As described above, the forming step and the sintering step can be simplified, and a ferroelectric excellent in homogeneity and piezoelectricity can be manufactured at low cost.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 Hereinafter, an embodiment according to the present invention will be described. The positioning of the piezoelectric body and the ferroelectric is called ferroelectric if the polarization can be reversed by an external electric field in the piezoelectric.
Here, PZ which is a typical piezoelectric substance and also a ferroelectric substance
Reference is made to T ceramics. It is known that ferroelectrics containing Pb generally have large residual polarization, relative permittivity, and piezoelectric constant, and are excellent in piezoelectricity and ferroelectricity. With the sol-gel method, a metal alkoxide is dissolved in alcohol and hydrolyzed under an acid catalyst, whereby the metal atom and the metal atom are bonded via an oxygen atom, and the solution changes from the sol to the gel depending on the time of hydrolysis. Transfer and the crosslink density increases. The greatest advantage of the sol-gel method is that oxides can be synthesized at a low temperature, and as a result, it is possible to enjoy the advantages such as energy saving, less evaporation loss, less air pollution, and less pollution from containers. . In order to make it from solution,
There are also advantages such as good homogeneity and high purity. In addition, the optical fiber currently in practical use has been replaced by the sol-gel method from the conventional method because the shape can be provided. A method for producing a ferroelectric substance by a sol-gel method will be described in detail. First, PZT ceramics, which are ferroelectric and piezoelectric, are oxides composed of elements Pb, Zr, and Ti. Therefore, respective metal alkoxides, namely, diethoxy lead, titanium tetraisopropoxide, and zirconium tetranormal butoxide are used. Prepare First, 2.67 g (0.0094 mol) of titanium tetraisopropoxide is dissolved in 100 g of isopropanol, and 100 g of a 0.001 N hydrochloric acid solution in isopropanol is added to the solution.
And refluxed for 8 hours. This reaction causes T
The i atom and the Ti atom are bonded via the oxygen atom, and the high molecular weight is promoted. After this reaction, 20 g of 0.0188 mol of ethoxyethanol is added, and the mixture is refluxed for 0.5 hour.
This solution is used as a titanium precursor solution. Next, 4.06 g (0.0106 mol) of zirconium tetranormal butoxide was dissolved in 100 g of isopropanol, and 20 g of 0.0212 mol of ethoxyethanol was added to the solution, and a solution of 0.001 N hydrochloric acid in isopropanol 10 was added.
Add 0 g slowly and reflux for 8 hours. This reaction promotes Zr to have a high molecular weight similarly to Ti, and this solution is used as a zirconium precursor solution. After mixing the titanium precursor solution and the zirconium precursor solution, the mixture is refluxed for 0.5 hour. 5.94 g of diethoxy lead (0.04 g) was added to this mixed solution.
2 mol) and refluxed for another 0.5 hour to obtain a PZT precursor solution. In PZT ceramics, the composition ratio weighed this time, that is, Pb: Zr: Ti = 1: 0.53:
At 0.47, the relative permittivity, piezoelectric constant, etc. show the maximum values,
It is known that the relative permittivity / piezoelectric constant is greatly reduced when deviated from that.

Next, the PZT precursor is poured into a predetermined container such as a crucible or the like and baked at 650 ° C.
Fine particles are obtained. The PZT fine particles synthesized by this method are very small having an average particle size of as small as 0.1 μm or less, having a small particle size distribution, and having extremely excellent uniformity.

The PZT fine particles were molded by applying a pressure of 400 kg / cm, and then fired at 800 ° C. to obtain PZT ceramics. FIG. 1 shows a fractured surface of the sample produced by the above method. As can be seen, very dense PZT ceramics having excellent homogeneity were obtained.

By controlling the amount of powder to be added, the film thickness can be easily controlled.

Since the average particle diameter of the PZT fine particles as the starting material is 0.1 μm or less, and the average particle diameter of the sample produced this time is about 0.8 μm, the particle diameter increases slightly less than 10 times to 850 ° C. It was confirmed that it was sintered at a low temperature.

Further, this sample was crushed in an agate mortar, and the crystal structure was analyzed by XRD. As a result, it was confirmed that the sample was a PZT phase.

In the present invention, PZT synthesized by the sol-gel method is used.
Although a ferroelectric material was obtained by pressure-molding only the fine particles, a solvent / binder or the like was added to the fine particles to form a slurry, and then a ferroelectric material was produced using a method such as tape molding / printing. It can be easily inferred that the same effect as that obtained by pressure molding can be obtained.

Example 2 The above PZT fine particles were heated at 850 ° C.
After that, dense PZT ceramics were obtained. Since the firing temperature was 50 ° C. higher than that in Example 1, the average particle size was slightly increased from that at 800 ° C. firing. FIG. 2 shows a fracture surface of the sample.

Further, this sample was ground in an agate mortar, and the crystal structure was analyzed by XRD. As a result, it was confirmed that the sample was a PZT phase.

Example 3 The above PZT fine particles were heated at 700 ° C.
After firing, pores were generated, but the average particle size was 0.4μ.
m, which is four times as large as that of PZT fine particles as a starting material, and it was confirmed that sintering was performed even at a low temperature of 700 ° C. From this, it was found that the sintering start temperature was less than 700 ° C. FIG. 3 shows a cross-sectional view of the sample.

Further, this sample was ground in an agate mortar, and the crystal structure was analyzed by XRD. As a result, it was confirmed that the sample was a PZT phase.

[0022]

As described above, when ferroelectric ceramics are produced using ferroelectric fine particles synthesized by the sol-gel method, the average particle diameter is very small, 0.1 μm or less, and the particle surface is active. Can lower the temperature. When the firing temperature can be lowered, in the case of ferroelectric ceramics containing Pb, P
Since there is no need to take measures against evaporation of b, there are advantages that the firing step can be simplified, the range of selection of the internal electrode material for lamination can be widened, and the molding pressure can be reduced. Further, since the particle size variation of the fine particles synthesized by the sol-gel method is small, a ferroelectric film excellent in homogeneity, which can reduce molding pressure and can be manufactured. As described above, by using the ferroelectric fine particles synthesized by the sol-gel method, it is possible to manufacture a ferroelectric substance having excellent ferroelectric properties.

[Brief description of the drawings]

FIG. 1 is a photograph showing a fracture surface of a sample prepared by firing at 800 ° C. according to the present invention.

FIG. 2 is a photograph showing a fracture surface of a sample prepared by firing at 850 ° C. according to the present invention.

FIG. 3 is a photograph showing a fracture surface of a sample prepared by firing at 700 ° C. according to the present invention.

Claims (3)

[Claims] 1. A method for producing a ferroelectric material, comprising using ferroelectric fine particles having an average particle size of 0.1 μm or less. 2. The method of claim 1, wherein the fine particles are synthesized by a sol-gel method. 3. The method according to claim 1, wherein the fine particles contain a Pb component.