JP6950404B2 - A method for producing a liquid composition for forming a piezoelectric film and a method for forming a piezoelectric film using this liquid composition. - Google Patents

Description

The present invention is a method for producing a liquid composition for forming a piezoelectric film which does not contain lead, does not contain a highly toxic and corrosive solvent, has excellent storage stability, and has few voids in the membrane, and this liquid. The present invention relates to a method for forming a piezoelectric film using a composition.

Lead zirconate titanate (PZT) is well known as a piezoelectric material. However, since PZT contains lead, a lead-free, that is, lead-free piezoelectric material is required for the purpose of reducing the environmental load. Examples of the method for forming the piezoelectric film include a solid phase method, a gas phase method, and a chemical solution method. The solid phase method has a problem that the firing temperature is high because a piezoelectric film is formed by physically mixing, crushing, and molding the oxide powder and then firing at 1000 to 1300 ° C. Further, the sputtering method, which is a vapor phase method, is a method of forming a piezoelectric film by colliding, for example, ionized argon or the like with an oxide target in a vacuum and depositing the elements ejected by the collision on a substrate. However, there is a problem that the composition deviates from the oxide used as the target, and it is not suitable as a method for forming a piezoelectric film using multiple elements. In addition, since a high vacuum is required, it is unavoidable to increase the size of the device.

On the other hand, in the chemical solution deposition (CSD) method, a precursor solution containing a metal element having a target composition is used to form a film on a substrate by, for example, a spin coating method, a dip coating method, an inkjet method, or the like, and then fired. Because it is a method of forming a piezoelectric film, it is possible to form a piezoelectric film at a lower temperature than the solid phase method, and because it does not require a high vacuum, it can be formed with a small device. preferable.

Conventionally, as one of the methods for forming a piezoelectric film by the CSD method, a piezoelectric material having a structural formula of _{(Bi 0.5} Na _0.5 ) TiO _3- (Bi _0.5 K _0.5 ) TiO _3- Bi (Mg _0.5 Ti _0.5 ) O ₃ A method for forming a film (see, for example, Non-Patent Document 1) has been proposed. In Non-Patent Document 1, 72.5 mol _{(Bi 0.5 Na 0.5) TiO 3} -22.5 mol _{(Bi 0.5 K 0.5) TiO 3} -5 mol _{Bi (Mg 0.5 Ti 0.5) O} 3 (BNT-BKT-BMgT) After reporting that the bulk ceramic of No. 1 exhibits a large high electric field piezoelectric constant (d ₃₃ ^* = 570 pm / V), silicon obtained by platinumizing a piezoelectric film having the same composition as the above composition using the CSD method. It is formed on the substrate.

In the method shown in Non-Patent Document 1, it is necessary to excessively dope the precursor solution with volatile cations in order to obtain a pure phase perovskite, and a heat treatment temperature of 700 ° C. improves the piezoelectric properties. (P _max = 52μC / cm ² and P _r = 12μC / cm ²⁾ that, quantitative compositional analysis of the film subjected to heat treatment at 650 ° C. and 700 ° C. to exhibit the achievement of near theoretical atomic ratio, electron microscopy through thickness The compositional variation observed in is in good agreement with the presence of voids formed between the continuous spin-coated layers, and the strain measurements of both poles and single poles were made with a dual beam laser interferometer at about 75 pm / V. It is shown that a high piezoelectric constant (d _{33, r) was obtained.}

In this method, bismuth acetate, sodium acetate trihydrate, potassium acetate, magnesium acetate tetrahydrate, and titanium isopropoxide are used as liquid precursors. First, titanium isopropoxide is stabilized with acetic acid in a dry atmosphere to prepare a Ti solution in order to prevent the reaction of water in the atmosphere with the titanium precursor. Next, bismuth acetate is dissolved in propionic acid, and sodium acetate, potassium acetate, and magnesium acetate are separately dissolved in methanol to prepare Bi, Na, K, and Mg solutions. Next, an appropriate amount of Bi, Na, K and Mg solutions is carefully added dropwise to the Ti solution using a syringe. When preparing the solution, add an excess of cations to compensate for the high volatility of the cations.

YH Jeon et al., "Large Piezoresponse and Ferroelectric Properties of (Bi0.5Na0.5) TiO3- (Bi0.5K0.5) TiO3-Bi (Mg0.5Ti0.5) O3 Thin Films Prepared by Chemical Solution Deposition", J . Am. Ceram. Soc., 1-7 (2013)

However, the piezoelectric film formed by the method shown in Non-Patent Document 1 has a high void ratio and has a problem that it does not become a dense film. Further, since propionic acid having corrosiveness is used as a solvent, there is a problem that it is necessary to take measures against corrosion of the manufacturing apparatus at the time of mass production. In addition, there is a problem that methanol is used as a solvent and is highly harmful to the human body.

An object of the present invention is a method for producing a liquid composition for forming a piezoelectric film which does not contain lead, does not contain a highly toxic and corrosive solvent, has excellent storage stability, and has few voids in the film. It is an object of the present invention to provide a method for forming a piezoelectric film using this liquid composition.

A first aspect of the present invention is a method for producing a liquid composition for forming a alkoxide film composed of a metal oxide containing Bi and Ti as main components and Na, K and X as subcomponents. A Ti stabilization step in which Ti alkoxide and a stabilizer are mixed and refluxed to prepare a first mixed solution, and a Bi raw material, a Na raw material, a K raw material, and an X raw material are mixed together in this first mixed solution and refluxed. A raw material mixing step of preparing a second mixed solution, a hydrolysis step of mixing water with the second mixed solution and refluxing to prepare a third mixed solution, and a hydrolysis step of mixing an organic solvent with the third mixed solution and refluxing. In the hydrolysis step, the solution containing Ti alkoxide, which is the second mixed solution, contains 5 to 20 with respect to 100 mol% of Ti elements in the Ti alkoxide. a method for producing a mole% of water is reacted by mixing the second mixture, wherein the benzalkonium be partially hydrolyzing the Ti alkoxide liquid composition. However, X is at least one of Mg, Zn and Ni.

The second aspect of the present invention is the invention based on the first aspect, and the reaction in the hydrolysis step is a mixture of the solution containing Ti alkoxide and the water at a temperature of 100 to 150 ° C.30. This is a method for producing a liquid composition, which is carried out by refluxing for about 60 minutes.

The third aspect of the present invention is the invention based on the first aspect , wherein the metal raw material of Na and / or K among the metal raw materials other than Ti of the metal oxide is Na alkoxide and / or K alkoxide. This is a method for producing a liquid composition in which an amine-based stabilizer is mixed together with the metal raw material and a solvent.

The fourth aspect of the present invention is the piezoelectricity obtained by applying a liquid composition produced by a method based on any one of the first to third aspects to a substrate, calcining the substrate, and then firing and crystallizing the liquid composition. It is a method of forming a body membrane.

A fifth aspect of the present invention is an invention based on the fourth aspect, the piezoelectric film, the main component of Bi and Ti, Ri Do a metal oxide containing Na, K and X as a sub-component a formation method of the piezoelectric void index of the film is Ru der 10% less pressure collector film. However, X is at least one of Mg, Zn and Ni.

The sixth aspect of the present invention is the invention based on the fifth aspect , wherein the metal oxide is (Bi _0.5 Na _0.5 ) TiO _3- (Bi _0.5 K _0.5 ) TiO _3- Bi (X _0.5 Ti _0.5 ). This is a method for forming a piezoelectric film having a composition of O _3.

In the method for producing a liquid composition according to the first aspect of the present invention, in the hydrolysis step, water is mixed with a liquid containing Ti alkoxide, which is a second mixture, and reacted to partially hydrolyze the Ti alkoxide. By doing so, the alkoxide is desorbed and a Ti—O—Ti network is formed in the liquid composition. As a result, the residue of carbon (C) in the piezoelectric film formed of this liquid composition is suppressed, and the piezoelectric film having few voids can be formed. Further, the obtained liquid composition does not contain lead, does not contain a highly toxic and corrosive solvent, has excellent storage stability, and does not precipitate even if stored at room temperature for 1 month after production.
Further, in the method for producing a liquid composition according to the first aspect of the present invention, Ti alkoxide and a stabilizer are mixed and refluxed before the hydrolysis step, so that water in the atmosphere reacts with Ti alkoxide first. It is possible to stabilize the Ti of the Ti alkoxide without doing so.
Further, in the method for producing a liquid composition according to the first aspect of the present invention, a metal oxide is added to a liquid in which Ti alkoxide and a stabilizer are mixed and refluxed after the Ti stabilization step and before the hydrolysis step. Since all the metal raw materials other than Ti and the solvent are mixed together and the mixed solution is refluxed, the liquid composition in one pot in a short time as compared with the conventional method of injecting all the metal raw materials separately. Can be manufactured.

In the method for producing a liquid composition according to the second aspect of the present invention, the reaction in the hydrolysis step is carried out by refluxing a liquid containing a Ti alkoxide and a liquid in which water is mixed at a temperature of 100 to 150 ° C. for 60 to 180 minutes. , The alkoxide is sufficiently desorbed in the liquid composition, and the Ti—O—Ti network is surely formed.

In the method for producing a liquid composition according to the third aspect of the present invention, by using Na alkoxide and / or K alkoxide as the metal raw material of Na and / or K, these alkoxides are more liquid than other metal raw materials. Since the thermal decomposition temperature of the liquid composition is lowered during the heat treatment after the composition is applied to the substrate, the residual carbon in the film is reduced, and a more dense alkoxide film can be formed. By using an amine-based stabilizer, a rapid hydrolysis reaction is suppressed, and uniform coating becomes possible.

In the method for forming a piezoelectric film according to the fourth aspect of the present invention, since the piezoelectric film is formed from the above liquid composition, it is possible to form a dense film that is lead-free and has few voids in the film.

The piezoelectric film formed by the method of the fifth aspect of the present invention has a feature of being lead-free and having few voids in the film.

The piezoelectric film formed by the method of the sixth aspect of the present invention has a metal oxide of (Bi _0.5 Na _0.5 ) TiO _3- (Bi _0.5 K _0.5 ) TiO _3- Bi (X _0.5 Ti _0.5 ) O ₃ . Since it has a composition and is lead-free, it has the advantage of having a smaller environmental load than lead-based materials.

It is a flowchart which shows the process of manufacturing the liquid composition of embodiment of this invention. It is a photographic figure which imaged the cross section of the piezoelectric film on the Pt lower electrode of an Example and a comparative example by SEM. FIG. 2A is a cross-sectional photograph of the piezoelectric membrane of Example 2 when water is added, and FIG. 2B is a cross-sectional photograph of the piezoelectric membrane of Comparative Example 1 when water is not added. It is a figure.

Next, a mode for carrying out the present invention will be described with reference to the drawings.

[Method for producing liquid composition]
As shown in FIG. 1, the method for producing the liquid composition of the present embodiment includes a Ti stabilization step 11 in which a Ti (titanium) alkoxide and a stabilizer are mixed and refluxed to prepare a first mixed liquid, and the first mixture thereof. A raw material mixing step 12 in which a Bi (bismuth) raw material, a Na (sodium) raw material, a K (potassium) raw material, and an X raw material are mixed together in one mixed liquid and refluxed to prepare a second mixed liquid, and this second mixed liquid. It includes a hydrolysis step 13 in which water is mixed with water and refluxed to prepare a third mixed solution, and a dilution step 14 in which an organic solvent is mixed with the third mixed solution and refluxed to dilute the third mixed solution. Here, X in the preparation step 12 of the second mixed solution is at least one of Mg (magnesium), Zn (zinc) or Ni (nickel). The characteristic configuration of this embodiment is that steps 11 to 14 are performed in one pot. Here, in one pot (container), after preparing the first mixed solution in one container, Bi, Na, K and X raw materials are simultaneously charged into the first mixed solution in the same container and reacted. The second mixed solution is prepared, and then water is mixed with the second mixed solution in the same container to prepare the third mixed solution, and then the organic solvent is mixed with the third mixed solution in the same container. Refers to producing the liquid composition of the present embodiment.

[Stabilization process of Ti alkoxide]
In the method for producing the liquid composition of the present embodiment, first, Ti alkoxide as a Ti raw material and a stabilizer are mixed and refluxed in a container at a temperature of 100 to 150 ° C. for 30 to 60 minutes to prepare a first mixed liquid. do. The reason for stabilizing the Ti raw material first is to suppress the reaction between water in the atmosphere and Ti alkoxide. As Ti alkoxides, titanium tetraethoxydo: Ti (OEt) ₄ , titanium tetraisopropoxide: Ti (OiPr) ₄ , titanium tetra n-butoxide: Ti (OiBu) ₄ , titanium tetraisobutoxide: Ti (OiBu) ₄ , Titanium tetra t-butoxide: Ti (OtBu) ₄ , Titanium dimethoxydiisopropoxide: Ti (OMe) ₂ (OiPr) _{2, and the} like. Examples of the stabilizer include acetic acid and acetylacetone. The stabilizer is preferably mixed so as to have a molar ratio (Ti alkoxide: stabilizer) of 1: 1 to 1: 4 with respect to Ti alkoxide. The atmosphere of mixing and refluxing is not particularly limited, but a dry atmosphere such as a dry air atmosphere, a dry nitrogen atmosphere, or a dry argon atmosphere is preferable so that the water in the atmosphere does not react with the Ti alkoxide.

[Ingredient mixing process of Bi, Na, K, X]
Next, the Bi raw material, the Na raw material, the K raw material, and the X raw material are mixed together with the first mixed liquid obtained in the Ti stabilization step, and refluxed in the same container at a temperature of 100 to 150 ° C. for 30 to 180 minutes. 2 Prepare a mixture. Examples of the Bi raw material include bismuth acetate, bismuth 2-ethylhexanoate, bismuth nitrate (III), pentahydrate and the like. Examples of the Na raw material include sodium acetate, sodium 2-ethylhexanoate, sodium (Na) alkoxide and the like. Examples of the K raw material include potassium acetate, potassium 2-ethylhexanoate, potassium (K) alkoxide, and the like. Examples of Na alkoxide include sodium methoxide: Na ₂ (OMe), sodium ethoxide: Na ₂ (OEt), and sodium t-butoxide: Na ₂ (OtBu). Examples of K alkoxide include potassium ethoxyoxide: K ₂ (OEt) and potassium t-butoxide: K ₂ (OtBu). By using Na alkoxide and / or K alkoxide, these alkoxides lower the thermal decomposition temperature of the liquid composition during heat treatment after the liquid composition is applied to the substrate, so that the carbon in the membrane is lower than the acetate. The residue is reduced, and a more dense alkoxide film can be formed. When Na alkoxide is used as the Na raw material, or when K alkoxide is used as the K raw material, these alkoxides react quickly, so an amine-based stabilizer is mixed with these alkoxides so as to suppress the rapid reaction. do. Examples of the amine-based stabilizer include 2-methylaminoethanol, 2-dimethylaminoethanol, 1-amino-2-propanol, ethanolamine, dimethanolamine, diethanolamine, triethanolamine and the like. The amine-based stabilizer is preferably mixed so as to have a molar ratio (Ti: stabilizer) of 1: 0.2 to 1: 2 with respect to the Ti raw material.

Among the X raw materials, the Mg raw material includes magnesium acetate, 2-ethylhexanoate, and the like, and the Zn raw material includes zinc acetate, 2-ethylhexanoate, zinc nitrate, and the like, and the Ni raw material includes zinc acetate, zinc nitrate, and the like. Examples include nickel acetate, nickel 2-ethylhexanoate, and zinc nitrate. In the mixture of the Bi raw material, the Na raw material, the K raw material, the X raw material, and the Ti raw material, it is desirable that the ratio of A site ion: B site ion is 125: 100 to 105: 100. This is because the main A-site ions, Bi, Na, and K, evaporate during firing, and the film composition after firing deviates from the charged composition. The atmosphere of mixing and refluxing is not particularly limited, but a dry atmosphere such as a dry air atmosphere, a dry nitrogen atmosphere, or a dry argon atmosphere is preferable so that the water in the atmosphere does not react with each raw material. Bi raw material, Na raw material, K raw material and X raw material are added and mixed together in the first mixed solution, a solvent (for example, propylene glycol) is added, the mixture is refluxed in a nitrogen atmosphere, and distilled under reduced pressure to remove by-products. After that, a solvent (for example, propylene glycol) may be further added to this solution to adjust the concentration, and further, any solvent of n-butanol, ethanol, or isopropanol may be added to this solution.

[Hydrolysis process of Ti alkoxide with water]
Next, water is mixed with the second mixed solution obtained in the raw material mixing step of Bi, Na, K, and X, and the mixture is refluxed in the same container at a temperature of 100 to 150 ° C. for 60 to 180 minutes to prepare the third mixed solution. Prepare. If the reflux temperature is less than 100 ° C., partial hydrolysis of Ti alkoxide in the second mixed solution does not proceed. If the temperature exceeds 150 ° C., the reaction proceeds too quickly and control becomes difficult. It is preferably 120 to 130 ° C. Further, if the reflux time is less than 60 minutes, the partial hydrolysis of the Ti alkoxide in the second mixed solution does not proceed sufficiently. If it exceeds 180 minutes, the productivity deteriorates. It is preferably 90 to 120 minutes. The water is pure water such as distilled water or ion-exchanged water or ultrapure water. Water is mixed at a ratio of 5 to 20 mol%, preferably 10 to 15 mol% with respect to 100 mol% of the Ti element in the Ti alkoxide in the second mixed solution. If it is less than 5 mol%, the progress of hydrolysis is not sufficient, the desorption of alkoxide in the liquid composition is insufficient, the Ti—O—Ti network is not formed, and a dense film cannot be obtained. If it exceeds 20 mol%, hydrolysis proceeds excessively and precipitation occurs.

[Dilution step with organic solvent and production of liquid composition]
Further, an organic solvent is mixed with the third mixture in which Ti alkoxide is partially hydrolyzed, and the mixture is refluxed to dilute the third mixture. The liquid composition obtained by diluting this third mixed liquid is the liquid composition of the present invention. Examples of the organic solvent include ethanol, n-butanol, isopropanol and the like. Dilution is performed so that the oxide concentration in the third mixed solution, which is the liquid composition, is 5 to 20% by mass. If necessary, it is preferable to dilute the third mixture and then filter it with a filter to remove dust, because the pot life of the liquid composition can be extended.

Next, examples of the present invention will be described in detail together with comparative examples.

<Example 1>
Titanium isopropoxide and acetylacetone were added to the flask so as to have a molar ratio of 1: 4 with respect to titanium isopropoxide, and reflux was carried out in an oil bath at 150 ° C. for 30 minutes. Bismus 2-ethylhexanoate, sodium acetate trihydrate, potassium acetate, magnesium acetate tetrahydrate, and propylene glycol were added thereto, and the mixture was refluxed in an oil bath at 150 ° C. for 1 hour. The Bi raw material, the Na raw material, the K raw material, and the Mg raw material were mixed in a molar ratio (Bi: Na: K: Mg: Ti) at 60: 43.5: 13.5: 3: 100. After refluxing, ultrapure water was added at a ratio of 5 mol% to 100 mol% of Ti element in titanium isopropoxide in a state where the boiling of the liquid had subsided, and the mixture was refluxed again in an oil bath at 150 ° C. for 1 hour. Was done. After refluxing, the unreacted product was removed by reducing the pressure to 0.03 MPa with a portable aspirator. Ethanol was added to the obtained product to dilute it until the oxide concentration reached 15% by mass. The obtained liquid was filtered through a filter to remove dust, and a liquid composition was obtained.

<Examples 2 to 10 and Comparative Examples 1 to 3>
As shown in Table 1, the raw materials were selected, the mixed mol% of each raw material was determined, and the liquid compositions of Examples 2 to 10 and Comparative Examples 1 to 3 were obtained in the same manner as in Example 1. The item of "(water / Ti) x 100" in Table 1 is the amount of water added, and the amount of addition is mol% with respect to 100 mol% of Ti element in titanium isopropoxide.

<Example 11>
Sodium ethoxide was used instead of the sodium acetate trihydrate used as the Na raw material used in Examples 1 to 10, and 2-methylaminoethanol was used as the amine-based stabilizer. This amine-based stabilizer was mixed so as to have a molar ratio (Ti: stabilizer) of 1: 1 with respect to the Ti raw material. Other than that, as shown in Table 2, the raw materials were selected, the mixed mol% of each raw material was determined, and the liquid composition of Example 11 was obtained in the same manner as in Example 1.

<Example 12>
Sodium ethoxydo was used instead of the sodium acetate trihydrate of the Na raw material used in Examples 1 to 10, and potassium t-butoxide was used instead of potassium acetate of the K raw material, and 2-methyl was used as the amine-based stabilizer. Amino ethanol was used. This amine-based stabilizer was mixed with the Ti raw material so as to have a molar ratio (Ti: stabilizer) of 1: 2. Other than that, as shown in Table 2, the raw materials were selected, the mixed mol% of each raw material was determined, and the liquid composition of Example 12 was obtained in the same manner as in Example 1.

<Example 13>
Sodium methoxydo was used in place of the sodium acetate trihydrate of the Na raw material used in Examples 1 to 10, potassium ethoxide was used in place of potassium acetate of the K raw material, and 2-dimethylaminoethanol was used as a stabilizer. Using. This stabilizer was mixed with the Ti raw material so as to have a molar ratio (Ti: stabilizer) of 1: 1.4. Other than that, as shown in Table 2, the raw materials were selected, the mixed mol% of each raw material was determined, and the liquid composition of Example 13 was obtained in the same manner as in Example 1.

<Comparative evaluation test>
In order to evaluate the liquid compositions obtained in Examples 1 to 13 and Comparative Examples 1 to 3, a substrate with a Pt lower electrode was prepared by the following method. First, a 4-inch Si substrate was thermally oxidized to form a 500 nm oxide film on its surface. Ti was formed on the oxide film by a sputtering method to a thickness of 20 nm, and then fired in an infrared rapid heating (RTA) furnace in an oxygen atmosphere at 700 ° C. for 1 minute to form a titanium oxide film. A (111) oriented Pt lower electrode having a thickness of 100 nm was formed on the titanium oxide film by a sputtering method.

500 μL of the liquid compositions obtained in Examples 1 to 13 and Comparative Examples 1 to 3 were separately dropped onto the Pt lower electrode of the substrate, and spin coating was performed at 4000 rpm for 15 seconds. Further, calcination was carried out on a hot plate at 300 ° C. for 5 minutes. After repeating this operation three times, firing was performed in an infrared rapid heating furnace at 700 ° C., an oxygen atmosphere, a heating rate of 10 ° C. per second, and a holding time of 1 minute. The cross section of the obtained film is observed by SEM, and the area of the film portion and the void portion in the film is calculated by image analysis of the cross-sectional image. [Area of void portion / image area of film portion] × 100 The void rate (%) was calculated by performing the above calculation. These results are shown in Table 1. A cross-sectional photograph of the piezoelectric membrane of Example 2 is shown in FIG. 2 (a), and a cross-sectional photograph of the piezoelectric membrane of Comparative Example 1 is shown in FIG. 2 (b). As for the presence or absence of precipitation of the liquid, the obtained liquid composition was stored in a refrigerator at 5 ° C. for one month in a sealed container, and then the presence or absence of precipitation of the liquid composition was visually inspected.

As is clear from Table 1, in the liquid composition to which no water was added as in Comparative Example 1, precipitation of the liquid composition did not occur, but the void ratio was as high as 40%. Further, in the liquid composition in which only 3 mol% was added with respect to 100 mol% of the Ti element as in Comparative Example 2, precipitation of the liquid composition did not occur, but the void ratio was as high as 28%. Further, in the liquid composition in which a large amount of 22 mol% was added with respect to 100 mol% of the Ti element as in Comparative Example 3, the liquid composition was precipitated and the void ratio was as high as 24%.

On the other hand, in the liquid compositions of Examples 1 to 10, precipitation of the liquid composition does not occur, and 5 to 20 mol% of water is added to 100 mol% of Ti elements regardless of the film composition and the element ratio. By reacting and partially hydrolyzing, the void ratio was as low as 3 to 10%, and it was confirmed that a dense film could be obtained. From this, it was found that the liquid compositions of Examples 1 to 10 had good storage stability even though they did not contain highly toxic 2-methoxyethanol or highly corrosive acetic acid.

In particular, by comparing Examples 1 to 4 and Comparative Examples 1 to 3, when the amount of water to be reacted is less than 5 mol%, the densification of the membrane does not proceed sufficiently, and when it is more than 20 mol%. It was found that the storage stability of the liquid was poor and the denseness of the film was not sufficiently improved. Although the detailed mechanism is unknown, the amount of residual carbon in the film is reduced as a result of lowering the thermal decomposition temperature of Ti and its composite compound by hydrolyzing Ti with an appropriate amount of water, and during firing. It is considered that one of the causes is that the void formation caused by degassing was suppressed.

Further, as is clear from Table 2, Na alkoxide was used as the Na raw material and K alkoxide was used as the K raw material, respectively, as compared with Examples 1 to 10 in which sodium acetate was used as the Na raw material and potassium acetate was used as the K raw material. In Examples 11 to 13 used, since the thermal decomposition temperature of these alkoxides was lower than that of the acetate salt, the residual carbon in the film was reduced, and the void ratio was 3 to 4%. It was confirmed that a dense film could be obtained.

The piezoelectric film formed by using the liquid composition of the present invention can be used as a MEMS application such as a vibration power generation element, a pyroelectric sensor, an actuator, an inkjet head, and an autofocus.

Claims (6)

A method for producing a liquid composition for forming a piezoelectric film composed of a metal oxide containing Bi and Ti as main components and Na, K and X as sub-components.
A Ti stabilization step in which a Ti alkoxide and a stabilizer are mixed and refluxed to prepare a first mixed solution, and a Bi raw material, a Na raw material, a K raw material, and an X raw material are mixed together in this first mixed solution and refluxed. A raw material mixing step of preparing a second mixed solution, a hydrolysis step of mixing water with the second mixed solution and refluxing to prepare a third mixed solution, and a hydrolysis step of mixing an organic solvent with the third mixed solution and refluxing. Including a dilution step of diluting the third mixed solution
In the hydrolysis step, 5 to 20 mol% of water with respect to 100 mol% of the Ti element in the Ti alkoxide is mixed with the liquid containing the Ti alkoxide which is the second mixed solution. manufacturing method of the Ti alkoxide partially hydrolyzed to a liquid composition comprising a benzalkonium reacted.
However, X is at least one of Mg, Zn and Ni. The method for producing a liquid composition according to claim 1, wherein the reaction in the hydrolysis step is carried out by refluxing a liquid containing the Ti alkoxide and the water at a temperature of 100 to 150 ° C. for 60 to 180 minutes. Claim that the metal raw material of Na and / or K among the metal raw materials other than Ti of the metal oxide is Na alkoxide and / or K alkoxide, and the amine-based stabilizer is mixed together with the metal raw material and the solvent. 1. The method for producing a liquid composition according to 1. A method in which a liquid composition produced by the method according to any one of claims 1 to 3 is applied to a substrate, calcined, and then fired to form a crystallized piezoelectric film. The piezoelectric film is composed mainly of Bi and Ti, Na, Ri Do metal oxide containing K and X as an auxiliary component, wherein the piezoelectric film piezoelectric according to claim 4, wherein the void ratio is less than 10% of Method of forming body membrane.
However, X is at least one of Mg, Zn and Ni. The method for forming a piezoelectric film according to claim 5, wherein the metal oxide has _{a composition of (Bi 0.5} Na _0.5 ) TiO _3- (Bi _0.5 K _0.5 ) TiO _3- Bi (X _0.5 Ti _0.5 ) O ₃ .

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