JPH0664970A - Production of lead titanate zirconate - Google Patents

Abstract

PURPOSE:To inexpensively mass produce lead titanate zirconate of a shape with a high degree of freedom by dissolving a lead compound, a Zr compound and a titanium alkoxide in acetic acid to give a sol solution and burning the solution. CONSTITUTION:Given amounts of lead acetate, lanthanum acetate and zirconyl nitrate are mixed and blended with acetic acid while stirring to give a transparent mixed solution. Then titanium butoxide is dripped into the solution and about 2ml triethylene glycol based on 1/100mol of each raw material is added and stirred to give a sol solution. Then a base plate of quartz glass, etc., is immersed in the sol solution and pulled up at about 2-10cm/minute speed to form a gel film on the base plate. Then the prepared film is dried and burnt at 500-850 deg.C to produce lead titanate zirconate such as thin film of PLZT.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention has good translucency and has a large electro-optical effect. Therefore, in addition to its use as a conventional piezoelectric ceramic material, an image display device, an optical storage element, an optical modulator, etc. The present invention relates to a method for producing lead zirconate titanate (PLZT) containing lanthanum, which is expected to be applied to optoelectronics, and more specifically to a method for producing lead zirconate titanate using a sol-gel method.

[0002]

2. Description of the Related Art Conventional methods for producing PLZT include an oxide mixing method, a PVD (physical vapor deposition) method, and a CVD (chemical vapor deposition) method. The oxide mixing method is based on La ₂ O ₃ , P
bO, ZrO ₂ , and TiO ₂ are mixed by a wet method, dried and then pelletized by a dry method, and then a binder and a solvent are added to form a sheet, and these are fired at 1100 to 1200 ° C. 1100 to 1200 ° C. under a pressure of 500Kg / cm ^2, 5~1
There is a method of hot pressing in oxygen for 0 hours. Also, P
Known methods include a sputtering method, an EB vapor deposition method, and an ion plating method as the VD method, and a plasma CVD method, a MOCVD (metal organic chemical vapor deposition) method, and the like as the CVD method.

[0003]

In the oxide mixing method, P
Since volatilization of bO occurs and composition variation occurs, it is indispensable to add excess PbO in advance or perform firing in a PbO atmosphere, but it is difficult to control the PbO vapor pressure. In addition, there are problems such as contamination during powder mixing, the presence of agglomerated particles, and voids left by the removal of the binder remaining inside the ceramics, which hinders densification and deteriorates the piezoelectric characteristics.

Further, although the PVD method and the CVD method can form a dense film, it is necessary to select the substrate to be deposited. In addition, the device is expensive and mass production is not possible. Further, since a gas phase is used as a raw material, there is a problem that composition control becomes difficult.

[0005]

In order to solve the above-mentioned problems, a lead compound and
Using zirconium compound and titanium alkoxide as raw materials,
A sol solution is prepared by using acetic acid as a solvent, and this is baked.

In order to solve the above problems, the invention according to claim 2 uses an inorganic or organic lanthanum compound other than chloride, a lead compound, a zirconium compound and a titanium alkoxide as raw materials, and acetic acid as a solvent. As the above, a sol solution is prepared and then baked.

[0007]

According to the method for producing lead zirconate titanate of the present invention, by using the sol-gel method, the sol-gel method has characteristics equivalent to those of the conventional method without controlling the atmosphere at a temperature as low as 850 ° C. or less. PLZT with uniform composition in molecular order
Can be fired. Further, the thus fired PLZT has a large degree of freedom in shape and can be mass-produced. In addition to the use as a conventional piezoelectric magnetic material utilizing the characteristics of PLZT, an image display device, an optical storage element, etc. It can be applied to a wide range of optoelectronics such as optical modulators.

[0008]

EXAMPLE First, a sol solution of PLZT raw material is prepared. The raw materials for the lanthanum, lead and zirconium compounds may be either organic or inorganic compounds as long as they are not chlorides. For example, lanthanum acetate and lanthanum nitrate are preferably used as raw materials for the lanthanum compound, lead acetate, lead nitrate and lead stearate are used as lead compounds, and zirconyl nitrate and zirconium propoxide are used as zirconium compounds.
Titanium alkoxide is used as the titanium raw material.
This alkoxide is subsequently polycondensed and allows gelation. As the titanium alkoxide, titanium ethoxide,
Titanium isopropoxide and titanium butoxide are preferably used.

A sol solution can be prepared from these raw materials by using acetic acid and alcohol as solvents.
Lanthanum, lead, zirconium and titanium raw materials can
Blend according to LZT composition, add acetic acid and alcohol to this and stir until a clear sol solution is obtained.
The alkoxide is easily hydrolyzed, so it is better to add it last. The concentration of acetic acid is 8.5N, about 10 ml is added to 1/100 mol of each raw material of PLZT. To the sol solution, in order to adjust the viscosity of the solution and make it highly stable, about 2 ml of ethylene glycol is added to 1/100 mol of each PLZT raw material,
It is desirable to stir. The first method of gelling this sol solution is to form a film on a substrate by a method such as a dip coating method, a spin coating method, an ultrasonic coating method, etc. After the film is formed, it is gelled.

Therefore, according to the present invention, PLZ is changed from the sol solution.
The first method for producing T is a method in which a gel film is formed on the substrate by various coating methods as described above and then fired at a temperature of 850 ° C. or lower, preferably 600 to 800 ° C. Second
The method is that the sol solution is placed in a container (for example, a crucible) that does not scatter during heating, calcined at 500 to 750 ° C, and
This is a method in which ZT powder is obtained, shaped and fired. The firing temperature is 800 ° C or lower, preferably 600 to 800 ° C.
In the third method, the sol solution is slowly dried (eg, allowed to stand at room temperature for 1 week) to be gelled, and the obtained gel-forming body is
This is a method of firing at a temperature of 800 ° C or lower.

FIG. 1 is a flow chart showing an example of the manufacturing process of the sol solution. Predetermined amounts of lead acetate trihydrate, lanthanum acetate sesquihydrate and zirconyl acetate dihydrate are added, and after adding acetic acid to the mixture, the solution is stirred until it becomes completely transparent. Next, a predetermined amount of titanium butoxide monomer is dropped using a buret or the like. To this mixed solution, ethylene glycols were added to each raw material 1 /
A sol solution is obtained by adding 2 ml to 100 mol and stirring. Substrates such as quartz, quartz glass with ITO, soda glass, and Pt plate are immersed in this, and 2-10 cm / min
At a speed of 1 to form a gel film on the substrate.
Depending on the number of times of pulling up, PLZT having a desired film thickness
A thin film can be formed. Here, about 0.18 per pull
The film thickness is μm, and the film thickness can be easily controlled by the number of pulling operations.

The film sample thus obtained is called sample A. Here, the sample A may be a film formed by a spin coating method or an ultrasonic coating method, and the film thickness can be controlled by the spin speed and the spray time. A powder sample obtained by drying the sol solution prepared above and baking it at 500 to 850 ° C. is referred to as Sample B. From the results of the film thickness and the powder X-ray diffraction, a perovskite phase began to precipitate from 500 ° C. in both Samples A and B, and became a perovskite phase by heat treatment at 600 ° C. From this, it was found that a PLZT single phase was obtained by heat treatment at 600 ° C. or higher. Next, for sample A, 30
As a result of measuring the transmittance from 0 to 800 nm, the film thickness is about 2 μm.
Even at m, the transmittance was about 70% near 600 nm.

An example of the dielectric constant of a typical composition of PLZT obtained in the above process is shown in FIG. Lead zirconate titanate (PLZT) containing lanthanum is Pb _{1-X / 100} La
_{X / 100} (Zr _{Y / 100} Ti _{Z / 100} ) _{1-X / 400} O ₃ [however, 0
≤ _x ≤ 1]. PLZ in the figure
T composition, for example in the _{PLZT (X / Y / Z)} , 9/65/35
Is Pb _0.93 La _0.07 (Zr _0.65 Ti _0.35 ) _0.978 O ₃ ,
_{7/65/35 Pb 0.93 La 0.07 (Zr 0.65 Ti} 0.35) 0.983
Indicates O ₃ . For example, _7/65/35 PLZT of the respective raw materials 1/10
0 mol, that is, lead acetate trihydrate 3.546 g, lanthanum acetate 1.5
Hydrate 0.240g, Zirconyl nitrate dihydrate 1.760g 8.5N
10.00 ml of acetic acid of 0 is added and dissolved by stirring. to this,
Add 0.01 mol of titanium butoxide dropwise, and further add 2.0 ml of triethylene glycol to prepare a sol solution, and then immerse it in a quartz substrate coated with ITO 10 times to form a 2.0 μm thick gel film. After forming, 700-850 ℃
It was prepared by firing at the temperature of 2 to 4 hours.

FIG. 2 shows P when the measurement frequency is 10 kHz.
LZT _(x / _65/35) shows the respective thermal treatment temperature dependence of the dielectric constant of the thin film having a thickness of 2.0μm for each composition. As is clear from FIG. 2, when the firing temperature exceeds 800 ° C., the characteristics deteriorate. This is because the lead component scatters from the sample and compositional variation occurs. Further, in the case of firing at 800 ° C. or lower, it shows the same characteristics as those of the conventional powder sintering method, even though firing is performed in the air without controlling the atmosphere. Further, here, all of the samples using the dip coding method, the spin coding method, and the ultrasonic spray method showed the same characteristics.

Furthermore, 800 ° C. to Pt plate 3, of thickness 2.5μm was produced by 2.0 hours heat treatment PLZT _(x / _65/35)
Shows the temperature dependence of the loss factor tanδ of the complex dielectric constant of the thin film dielectric constant and _{PLZT (7/65/35)} . The measurement frequency at this time is 10 kHz. From Fig. 3, the thin film with the composition of _x = 8-9 deteriorates in characteristics when the firing temperature exceeds 100 ° C.
In the case of firing at a temperature of 00 ° C or lower, the characteristics are the same as those of the conventional powder sintering method, even though the firing is performed in the air without controlling the atmosphere. In addition, taking a thin film with a composition of _x = 7 as an example, the loss coefficient tan δ of its dielectric constant and complex dielectric constant
Let's compare the change of. 190 for a composition thin film with _x = 7
When the temperature exceeds ℃, the characteristics deteriorate, but the heat loss decreases at around the same temperature.

As described above, in the present invention, a lead compound, a zirconium compound, and a titanium alkoxide are used as raw materials, a sol solution is prepared using acetic acid as a solvent, and the sol solution is fired to control the atmosphere at a temperature as low as 850 ° C. or less without controlling the atmosphere. PLZT having the same characteristics as the conventional method and having a uniform composition in atomic or molecular order can be fired.

Also, by using inorganic and organic lanthanum compounds other than chlorides, lead compounds and zirconium compounds and titanium alkoxide as raw materials and using acetic acid as a solvent to prepare a sol solution, which is then calcined, it is also possible to obtain 850 ° C. or lower. It has the same characteristics as the conventional method without controlling the atmosphere at low temperature,
Moreover, PLZ has a uniform composition on the atomic or molecular order.
T can be fired.

The PLZT thus fired according to the present invention has a good light-transmitting property and has a large electro-optical effect.
Application as optoelectronics to image display devices, optical storage elements, optical modulators, etc. is also conceivable. For example, by attaching a PLZT film to a rearview mirror of an automobile and electrically vibrating the film, it is possible to repel water in the rearview mirror even on a rainy day and improve the traveling safety of the automobile.

[0019]

As described above, according to the present invention, by using the sol-gel method, it has the same characteristics as the conventional method without controlling the atmosphere at a temperature as low as 850 ° C. PLZT having a uniform composition can be fired on the order. Furthermore, the PLZT thus fired is inexpensive, has a high degree of freedom in shape, and can be mass-produced.

The PLZT thus fired according to the present invention has a good translucency and a large electro-optical effect, and therefore, in addition to the conventional use as a piezoelectric magnetic material,
It can be applied to image display devices, optical storage elements, optical modulators and the like in a wide range of fields as optoelectronics.

[Brief description of drawings]

FIG. 1 is a flow chart showing an example of a process for producing a sol solution according to the present invention.

2 is a diagram showing each heat treatment temperature dependence of the dielectric constant of the thin film having a thickness of 2.0μm of PLZT _(X / _65/35) each composition.

[Figure 3] was produced in the Pt _{substrate, PLZT (X / 65/35} )
FIG. 5 is a diagram showing temperature dependence of loss coefficient tan δ of thin film dielectric constant and complex dielectric constant.

Claims (2)

[Claims] 1. A method for producing lead zirconate titanate, which comprises using a lead compound, a zirconium compound, and a titanium alkoxide as raw materials to prepare a sol solution using acetic acid as a solvent and firing the solution. 2. A lanthanum characterized in that an inorganic or organic lanthanum compound other than chloride, a lead compound, and a zirconium compound and a titanium alkoxide are used as raw materials, a sol solution is prepared using acetic acid as a solvent, and this is calcined. A method for producing lead zirconate titanate containing.