JP2000124515A - Manufacture of ferroelectric element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contrive to form a film which is high in film density and in electrical characteristics, when a ferroelectric element is formed using a sol-gel method. SOLUTION: PZT sol-gel powder is dispersed in an alcoholic solvent, a dispersant, a plasticizing agent and a binder are added to the alcoholic solvent to stir fully the solvent, and a PZT paste is made. A sol-shaped PZT precursor solution is added within this paste, whereby a mixed paste is made, the paste is applied on a substrate, and a PZT film obtained by drying and firing the paste is higher than a conventional PZT film in film density and is better than the conventional PZT film in electrical characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a piezoelectric or ferroelectric element used as a piezoelectric element in an ink jet recording apparatus or the like.

[0002]

2. Description of the Related Art A technique for producing a ferroelectric paste using ferroelectric fine particles and producing a ferroelectric film by screen printing or a bar coater is well known. Techniques for preparing pastes using ferroelectric fine particles prepared by the solid-phase method have been well known, but recently, techniques for preparing ferroelectric fine particles by the sol-gel method and forming them into paste have also been known. It became so. A conventional technique for producing a ferroelectric film by a paste using ferroelectric fine particles by a sol-gel method will be described.

[0003] 2.67 g (0.0094 mol) of titanium tetraisopropoxide was dissolved in 100 g of isopropanol to prepare a titanium solution. Then, in order to increase the molecular weight of titanium tetraisopropoxide, a 0.001 N hydrochloric acid isopropanol solution 1 was added to the obtained titanium solution.
The hydrolysis was carried out by gradually adding 00 g. After refluxing for 8 hours at a temperature of 82.5 ° C., the boiling point of isopropanol, 0.0188 mol of ethoxyethanol was added. As a result, a titanium precursor solution was obtained. Separately, 4.06 g (0.0106 mol) of zirconium tetranormal butoxide was dissolved in 100 g of isopropanol to prepare a zirconium solution. To the obtained zirconium solution, 0.0212 mol of ethoxyethanol was added, and 100 g of 0.001 N hydrochloric acid in isopropanol was gradually added to carry out hydrolysis. During the reflux at 82.4 ° C. for 8 hours, the molecular weight of zirconium tetranormal butoxide progressed, and a zirconium precursor solution was obtained. After mixing the titanium precursor solution and the zirconium precursor solution separately prepared as described above, reflux was further continued for 0.5 hour. To the resulting mixture was added 5.94 g (0.02 mol) of diethoxylead, and the mixture was refluxed at 82.4 ° C. for 0.5 hours. As a result, a PZT precursor solution (a) was obtained. Here, the composition ratio of Zr and Ti in PZT is closely related to the obtained ferroelectricity. Therefore, when preparing the isopropanol solution as described above and mixing these solutions here, this point is also considered. Considering the above, the desired composition ratio (Pb: Zr: Ti:
O = 1: 0.53: 0.47: 3).

[0004] PZT fine particles can be obtained by pouring the PZT precursor solution (a) into a predetermined container such as a crucible and baking it at 650 ° C. PZ synthesized by this method
The T fine particles have a very small average particle size of 0.1 μm or less, have a small variation in particle size distribution, and are extremely excellent in uniformity. A solvent,
A PZT paste was obtained by adding a binder, a dispersant, a plasticizer, and the like and sufficiently stirring. This paste is applied on a Si substrate with Pt by screen printing, and 800
By firing at 30 ° C. for 30 minutes, a PZT perovskite film having a thickness of 20 μm was obtained.

[0005]

However, the PZT film produced by such a method has the disadvantage that the film density is low and the piezoelectric characteristics are poor.

[Object of the Invention] An object of the present invention is to solve the above-mentioned problems and to produce a ferroelectric film having a high film density and excellent electric characteristics.

[0007]

Means for Solving the Problems In order to solve the above problems, a method of manufacturing a ferroelectric element according to the present invention employs the following configuration. That is, the method for manufacturing a ferroelectric element of the present invention comprises the steps of: preparing a ferroelectric paste using ferroelectric fine particles; and adding a sol ferroelectric precursor solution to the ferroelectric paste. And a step of producing a mixed paste. Claim 2
The method for producing a ferroelectric element according to claim 1, wherein the ferroelectric fine particles for producing a ferroelectric paste are obtained by hydrolyzing a metal alkoxide in the sol-like ferroelectric substance. It is characterized by being produced by firing a body precursor solution. According to a third aspect of the present invention, there is provided a method of manufacturing a ferroelectric element, wherein the sol ferroelectric element is added to the ferroelectric paste in order to produce a mixed paste. The amount of the body precursor solution is 10 wt% to 40 wt% based on the ferroelectric paste. Further, the method for manufacturing a ferroelectric element according to claim 4 is the method according to claim 1, claim 2 or claim 3.
Among the constitutions described in the above, a ferroelectric paste is produced using ferroelectric fine particles produced by firing a sol-like ferroelectric precursor solution obtained by hydrolyzing a metal alkoxide, The method is characterized in that the paste is mixed with the sol-form ferroelectric precursor solution to prepare a mixed paste, and the mixed paste is applied on a predetermined substrate, dried and fired. That is, a ferroelectric paste is produced from ferroelectric fine particles produced by firing a sol-like ferroelectric precursor solution obtained by hydrolyzing a metal alkoxide, and the sol-like ferroelectric paste is further poured into the ferroelectric paste. A mixed paste is prepared by mixing and sufficiently stirring the dielectric precursor solution, and the mixed paste is applied to a substrate, dried and fired to obtain a desired ferroelectric element.

(Action) In order to achieve the above object, according to the present invention, a ferroelectric sol-gel powder as ferroelectric fine particles is
A ferroelectric paste is prepared by dispersing in an alcohol solvent, adding a dispersant, a plasticizer, and a polymer binder and sufficiently stirring the mixture. A mixed paste is prepared by adding a sol ferroelectric precursor solution to the ferroelectric paste. Then, the mixed paste is applied to a substrate, dried and fired to obtain a ferroelectric film, that is, a ferroelectric element. As a result, the obtained ferroelectric film has a higher film density and better electric characteristics than the conventional ferroelectric film.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an ink jet head according to the best mode for carrying out the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram of an inkjet head.

In the ink chamber forming member 11, an ink chamber 12 for storing ink is formed.
The diaphragm 1 and the diaphragm 13 are closely bonded to each other by bonding or a method of integrally forming the diaphragm and the ink chamber.

The lower electrode 14 of the ferroelectric element 15 is formed at a position opposite to the ink chamber 12 of the diaphragm 13 by sputtering, screen printing, a sol-gel method, or the like. A ferroelectric element 15 is formed thereon by a sol-gel method,
Finally, the upper electrode 16 is formed by sputtering, screen printing, a sol-gel method, or the like.

Next, an operation method of the ink jet head shown in FIG. 1 will be described. Sandwiching the ferroelectric element 15,
By applying a voltage to the upper electrode 14 and the lower electrode 16, the ferroelectric element is displaced by utilizing the piezoelectric characteristics of the ferroelectric element, the diaphragm is pushed out to the ink chamber side, and the ink in the ink chamber is ejected. .

Next, a method of forming the ferroelectric element 15 will be described. FIG. 2 is a flowchart showing a method for forming a ferroelectric element according to the present invention. Using this flowchart, a method of forming a ferroelectric element according to the present invention will be described step by step while comparing with a conventional example. Step 1 Until the metal alkoxide solution is hydrolyzed to obtain ferroelectric fine particles. Step 2 Ferroelectric fine particles, solvent, binder, dispersant,
Step 3 Until a plasticizer is mixed to obtain a ferroelectric paste. Step 3 Until a sol ferroelectric precursor solution is added to the ferroelectric paste obtained in Step 2, until a mixed paste is obtained. Step 4 The mixed paste is applied to the substrate, dried and fired until a ferroelectric element is obtained.

Steps 1 to 4 will be described in more detail with reference to Examples. In the following description, a ferroelectric element and its manufacture will be described with reference to a typical example of a lead zirconate titanate (PZT) element.

[0015]

EXAMPLES (Example 1) (Step 1) 2.67 g (0.0094 mol) of titanium tetraisopropoxide, which is a metal alkoxide, was added to 100 parts.
g of isopropanol in the solution
100 g of 1N hydrochloric acid in isopropanol is gradually added, and the mixture is refluxed and hydrolyzed for 8 hours. After the reaction, 0.0188 mol of ethoxyethanol is added and stirred to obtain a mixed solution. This mixed solution is used as a titanium precursor solution. 4.06 g (0.0106 mol) of zirconium tetranormal butoxide, which is also a metal alkoxide
In 100 g of isopropanol,
0.0212 mol of ethoxyethanol is added, and 100 g of 0.001 N hydrochloric acid in isopropanol is gradually added. The mixture is refluxed for 8 hours and hydrolyzed. By this reaction, a high molecular weight reaction proceeds as in the case of titanium, and a mixed solution is obtained. This mixed 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, which is a metal alkoxide, was added to this mixed solution.
(0.02 mol) and refluxed for 0.5 hour to obtain a sol ferroelectric precursor solution. This sol ferroelectric precursor solution is referred to as a sol PZT precursor solution (a).

The sol-form PZT precursor solution (a) is placed in a crucible and fired at 650 ° C. for 1 hour. As a result, PZT fine particles, which are ferroelectric fine particles having an average particle diameter of 0.1 μm, were formed.

(Step 2) 21.09 g of n-butanol
(Solvent), 12.6 g of propylene carbonate (plasticizer), 2.19 g of ethylene glycol, 1.2 ethoxyethanol
4 g and 0.32 g of cyclohexanol (both dispersants) are weighed and mixed in a container. Polyvinyl butyral (hereinafter, referred to as “PVB”) having a molecular weight of 300 is mixed therein at a concentration of 25%. In the case of this embodiment, 12.5 g is mixed. The solution thus obtained is used as a PVB binder solution.

6 g of the PVB binder solution is taken out and placed in a plastic container. To this, 15 g of PZT fine particles having an average particle diameter of 0.1 μm prepared in advance in step 1 were added, and 2,000 rpm using a stirring and defoaming apparatus.
Stir at pm for 5 minutes. As a result, a homogeneous PZT paste as a ferroelectric paste was obtained.

As described above, the steps 1 and 2 follow almost the same steps as the conventional example, but the subsequent steps 3 and subsequent are the parts showing the features of the present invention.

(Step 3) Take out the PZT paste prepared in step 2 into a mortar, concentrate the sol-form PZT precursor solution (a) prepared in step 1 to 40% by weight of PZT using an evaporator, and add a pestle. And stir for 2 minutes. In the case of this example, the concentration is reduced to 16.29 g by using an evaporator to make PZT 40% by weight. The amount of P to be produced depends on the amount of the sol-form PZT precursor solution added here.
The electrical characteristics of the ZT film change. Usually, 0.3 g of the sol-form PZT precursor solution is added to 3 g of the PZT paste.
g to 1.2 g, that is, 10 to 40% by weight. Further, preferably, 0.6 g or more
0.9 g, that is, 20 to 30% by weight is preferably added. In this example, 0.3 g, 0.6 g, and 3 g of the sol-form PZT precursor solution were added to 3 g of the PZT paste.
Five types were prepared by adding 0.8 g, 0.9 g and 1.2 g, respectively. Further, for comparison with the present example, a conventional example in which the sol-form PZT precursor solution was not added was also prepared. As described above, the PZT fine particles that have been mixed in advance are uniformly dispersed in the binder solution and the sol-like PZT precursor solution, and the PZT concentration is higher at this point than when the paste is prepared using only the PZT fine particles. You can see that. Thus, a PZT mixed paste as a mixed paste was produced.

(Step 4) A platinum electrode is formed on a silicon substrate, and the PZT mixed paste prepared in Step 3 is applied thereon with a bar coater or the like, and the PZT mixed paste is applied at 50 ° C. for 30 minutes at room temperature.
Dry for 90 minutes at 250 ° C. for 0 minutes. Then, at a heating rate of 10 ° C./min.
The temperature was raised to 0 ° C., and the main firing was performed for 1 hour to obtain a perovskite PZT film having a thickness of about 30 μm.
That is, a ferroelectric element is manufactured.

A gold electrode was deposited on the PZT film thus obtained, and the electrical characteristics of the film were measured using an LCR meter. Table 1 shows the results. Table 1 shows how the relative dielectric constant of the fired film changes depending on the amount of the sol-form PZT precursor solution added in Step 3.

[0024]

[Table 1]

Table 1 shows how the relative dielectric constant, which is one of the electrical characteristics, changes when the amount of the sol-form PZT precursor solution added is changed. From this, PZT
When the precursor solution is added, the relative dielectric constant value is increased in any of the addition amounts in the range of 0.3 g to 1.2 g as compared with the case where the PZT precursor solution is not added. Further, when the PZT precursor solution is added in the range of 0.6 g to 0.9 g, the relative dielectric constant value is further increased as compared with the case where 0.3 g or 1.2 g of the PZT precursor solution is added.

(Embodiment 2) Another embodiment will be described with reference to Embodiment 2. This example is different from Example 1 mainly in the method of producing the sol-form PZT precursor solution in Step 1. (Step 1) 2.67 g (0.0094 mol) of titanium tetraisopropoxide, which is a metal alkoxide, was added to 100
g of isopropanol in the solution
100 g of 1N hydrochloric acid in isopropanol is gradually added, and the mixture is refluxed and hydrolyzed for 8 hours. After the reaction, 0.0188 mol of ethoxyethanol is added, and the mixture is refluxed and hydrolyzed for 0.5 hour after the reaction. 2.79 g (0.000 g) of diethoxy lead was added to this solution.
94 mol), refluxed for 0.5 hour and hydrolyzed to obtain a mixed solution. This mixed solution is used as a titanium lead precursor solution.

Similarly, 4.06 g of zirconium tetranormal butoxide, which is a metal alkoxide (0.01
(0.6 mol) in 100 g of isopropanol, 0.0212 mol of ethoxyethanol is added, and 100 g of 0.001 N hydrochloric acid in isopropanol is gradually added, followed by refluxing for 8 hours for hydrolysis.
By this reaction, a high molecular weight reaction proceeds as in the case of titanium. After this reaction, 3.15 g (0.0106 mol) of metal alkoxide and diethoxy lead are added, and the mixture is refluxed for 0.5 hour to obtain a mixed solution. . This mixed solution is used as a zirconium lead precursor solution.

After the titanium lead precursor solution and the zirconium lead precursor solution are mixed and refluxed for 0.5 hour, a sol ferroelectric precursor solution is obtained. This sol ferroelectric precursor solution is referred to as a sol PZT precursor solution (b).

The sol-form PZT precursor solution (b) is placed in a crucible and fired at 650 ° C. for 1 hour. As a result, PZT fine particles, which are ferroelectric fine particles having an average particle diameter of 0.1 μm, were formed.

(Step 2) 21.09 g of n-butanol
(Solvent), 12.6 g of propylene carbonate (plasticizer), 2.19 g of ethylene glycol, 1.2 ethoxyethanol
4 g and 0.32 g of cyclohexanol (both dispersants) are weighed and mixed in a container. Polyvinyl butyral (hereinafter, referred to as “PVB”) having a molecular weight of 300 is mixed therein at a concentration of 25%. In this case, 12.5 g is mixed. The solution thus obtained is used as a PVB binder solution.

6 g of the PVB binder solution is taken out and placed in a plastic container. To this, 15 g of the PZT fine particles prepared in advance in step 1 are added, and the mixture is stirred at 2000 rpm for 5 minutes using a stirring and defoaming apparatus.
As a result, a homogeneous PZT paste which was a ferroelectric paste was obtained.

As in the first embodiment, the features of the present invention will be described below from step 3 onward.

(Step 3) The PZT paste prepared in step 2 is taken out into a mortar, and the sol-form PZT precursor solution (b) prepared in step 1 is concentrated to 40% by weight of PZT using an evaporator. And stir for 2 minutes. In the case of this example, the concentration is reduced to 16.29 g by using an evaporator to make PZT 40% by weight. The electrical characteristics of the PZT film to be formed vary depending on the amount of the PZT precursor solution added here. Usually, 0.3 g of sol-form PZT precursor solution is added to 3 g of PZT paste.
It is preferable to add 1.2 g, that is, 10 to 40% by weight. Further, preferably, 0.6 g to 0.9 g
g, that is, 20 to 30% by weight. In this example, 0.8 g, that is, 27 wt% of the sol-form PZT precursor solution was added to 3 g of the PZT paste. In this way, the previously mixed P
The ZT fine particles are uniformly dispersed in the binder solution and the sol-like PZT precursor solution. It can be seen that the PZT concentration is higher at this point than when the paste was prepared using only the PZT fine particles. Thus, a PZT mixed paste as a mixed paste was produced.

(Step 4) A platinum electrode is formed on a silicon substrate, and the PZT mixed paste prepared in Step 3 is applied thereon using a bar coater or the like.
Dry for 90 minutes at 250 ° C. for 0 minutes. Then, at a heating rate of 10 ° C./min.
The temperature was raised to 0 ° C., and the main firing was performed for 1 hour to obtain a perovskite PZT film having a thickness of about 30 μm.
That is, a ferroelectric element is manufactured.

[0035]

According to the present invention, the ferroelectric sol-gel powder is
A ferroelectric paste is prepared by dispersing in an alcohol solvent, adding a dispersant, a plasticizer, and a binder and sufficiently stirring the mixture. A mixed paste is prepared by adding a sol-like ferroelectric precursor solution to the paste, and the paste is applied to a substrate, dried, and fired. And high electrical properties.
Further, even if firing is performed at a lower temperature than in the past, a ferroelectric element having good electric characteristics can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of an ink jet head using a ferroelectric element according to the present invention.

FIG. 2 shows PZT in Examples 1 and 2 of the present invention.
It is a figure which shows the flow of film production.

[Explanation of symbols]

 Reference Signs List 11 ink chamber forming member 12 ink chamber 13 diaphragm 14 lower electrode 15 ferroelectric element 16 upper electrode

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C04B 35/49

Claims (4)

[Claims] 1. A ferroelectric paste is prepared using ferroelectric fine particles, and a sol ferroelectric precursor solution prepared by hydrolyzing a metal alkoxide is added to the ferroelectric paste. A method for producing a ferroelectric element, comprising producing a mixed paste. 2. The ferroelectric element according to claim 1, wherein the ferroelectric fine particles are obtained by firing a sol-like ferroelectric precursor solution obtained by hydrolyzing a metal alkoxide. Production method. 3. The sol ferroelectric precursor solution to be added to the ferroelectric paste to produce a mixed paste is added in an amount of 10% by weight to the ferroelectric paste.
3. The method for producing a ferroelectric device according to claim 1, wherein the content is 40% by weight. 4. A mixed paste produced by adding a sol-like ferroelectric precursor solution produced by hydrolyzing a metal alkoxide to a ferroelectric paste produced using ferroelectric fine particles, is fixed on a substrate. 4. The method for manufacturing a ferroelectric element according to claim 1, wherein the ferroelectric element is manufactured through a process of applying, drying, and firing.