KR100890006B1 - PZT based piezoelectric thick film containing organic materials and nano pore, and preparation method thereof - Google Patents

Abstract

The present invention relates to a PZT-based piezoelectric thick film containing an organic material containing Pb (Zr _x Ti _1-x ) O ₃ and having nano-pores, and a method for manufacturing the same. The film deposition time is shorter than that of a thick film, and the film can be manufactured at a high heat treatment rate and a cooling rate. The thickness of the film that can be deposited is thick, so that the film has excellent electrical properties and stability. Therefore, the PZT-based piezoelectric thick film according to the present invention can be usefully used for sensors and actuators having high sensitivity, high power, stability and fast response speed.

PZT thick film, aerosol deposition method, organic material, pyrolysis, heat treatment, residual stress, nano fine pores

Description

PPT-based piezoelectric thick film containing organic material and nano-pores and method for preparing the same {PZT based piezoelectric thick film containing organic materials and nano pores, and preparation method}

1 (a) is a thermogravimetric analysis graph of the PZT powder according to the present invention, (b) is a graph showing the organic content according to the present invention;

Figure 2 (a) is a particle size analysis graph of the PZT powder according to the present invention, (b) is an electron scanning micrograph of the powder according to the present invention;

Of Figure 3 (a) is a heat treatment before and after picture of the PZT-based thick film of Comparative Example 1, (b) is a heat treatment before and after the picture in accordance with the present invention;

4 is an electron scanning microscope photograph of the cross section and the surface of the PZT-based thick film according to the present invention;

5 is an electron scanning microscope photograph of the microstructure of the PZT-based thick film according to the present invention according to the heat treatment step;

6 is an X-ray diffraction graph according to each manufacturing process of the PZT-based thick film according to the present invention;

7 is a graph showing the residual polarization of the PZT-based thick film according to the present invention, the ferroelectric properties of the constant electric field; And

8 is a graph showing dielectric properties of the PZT thick film according to the present invention.

The present invention relates to a PZT-based piezoelectric thick film containing an organic material and having nano-pores, and a method of manufacturing the same.

Piezoelectric effect can be divided into piezoelectric direct effect and piezoelectric inverse effect. Piezoelectric direct effect is a voltage generating function, and when an external stress or vibration displacement is applied to the piezoelectric element, an electric signal is generated at its output end. It is applied to various sensors. In addition, the piezoelectric adverse effect refers to a phenomenon in which a device causes mechanical displacement by applying a voltage to the piezoelectric element from the outside as a displacement generating function and is mainly applied to an actuator. The piezoelectric direct effect and the piezoelectric adverse effect are collectively called a piezoelectric effect, and ceramics having such a function are called piezoelectric materials.

It can be applied as an acceleration sensor using the principle that can convert vibration into electrical energy, and the device such as pickup of record disk, microphone, speaker, buzzer, etc. It is used. In addition, it can transmit and receive ultrasonic waves, so it is used as a probe (probe), fish detector of the ultrasonic sensor.

When a force or pressure is applied from the outside, high voltage sparks can be generated, which is applied to gas appliances and piezoelectric transformers. Other applications include ceramic filters, delay lines, ultrasonic cleaners, ultrasonic processors, ultrasonic welders, and ultrasonic humidifiers.

PZT-based oxide ceramics, a typical piezoelectric material, have excellent ferroelectricity, pyroelectricity, and piezoelectric properties, so that many applications are made in various fields in the form of a film as well as bulk. Recently, much attention has been paid to PZT-based thin films and thick films, which have advantages such as high sensitivity, high power, and fast response speed in manufacturing sensors and actuators using MEMS technology that meet the requirements of miniaturization and integration of electromechanical composite parts. It is concentrated.

PZT-based piezoelectric thick films having thicknesses of several tens of microns or more can obtain not only a large generation force but also excellent responsiveness and stable electrical characteristics, and meet the requirements of thin and short and high performance of piezoelectric components. It is expected to create infinite value by newly applying to various fields that have not been used in the past, but it is difficult to manufacture piezoelectric thick films having dense and excellent electrical properties by using conventional thick film manufacturing methods.

The screen printing method, which is one of the conventional representative PZT-based thick film manufacturing methods, is a method of depositing a film by compressing a paste on a desired substrate by mixing various additives with a raw material powder to form a paste. However, densification requires heat treatment at a high temperature of about 900 ° C. or higher, and when silicon is used as a substrate, an interfacial reaction between the silicon substrate and the film at high temperatures is inevitable. Therefore, a method of adding a material having a low melting point to lower the post-heating temperature for densification may be used, but the addition of a non-piezoelectric material has a problem of degrading the properties of the film.

The aerosol deposition method is a method of forming a dense coating layer on the surface of the substrate by spraying the ultra-fine particles of micron size or less at room temperature to the substrate at a supersonic speed by the difference in the internal pressure between the powder supply device and the substrate and the carrier gas. It has the advantage that a dense thick film can be manufactured at a high deposition rate. The exact film formation mechanism of the aerosol deposition method is not yet known, but since the final formed coating layer is composed of ultra-fine grains and amorphous particles of several tens of nanometers or less, the powder particles are further affected by the strong mechanical impact force generated when the powder particles and the substrate collide with each other. In order to reduce the small particle size and thereby create a new particle surface of the high energy state generated, strong bonding between particles is caused, and it is believed that densification has been achieved due to the progress of such bonding.

However, the inside of the coating layer formed by the aerosol deposition method contains a large number of defects due to the fracture of the powder particles by a strong mechanical impact force, especially in the case of PZT-based piezoelectric thick film has a very low physical properties. In addition, the microstructure composed of ultrafine grains and amorphous particles also adversely affect the electrical properties of the film. Therefore, in order to solve this problem, the PZT-based piezoelectric thick film manufactured by the aerosol deposition method must be heat-treated after deposition. The post-heat treatment removes defects in the film, and as the crystallization and grain growth occur, the electrical properties of the piezoelectric thick film are improved.

One of the characteristics of the piezoelectric thick film prepared by the aerosol deposition method is that a large residual compressive stress is applied to the inside of the film after deposition because the film is formed by colliding powder particles on the substrate. Is bigger. In addition, the difference in coefficient of thermal expansion between the film and the substrate also causes residual stress in the film. Therefore, even if the thick film manufactured by the aerosol deposition method is healthy, if the post-heat treatment is performed to improve the characteristics, the film and the substrate are separated from each other due to the difference in the coefficient of thermal expansion accumulated between the film and the substrate, thereby damaging the film. Easy to be This phenomenon becomes worse as the thickness of the film becomes thicker, and in order to solve this problem, a method of increasing the temperature and cooling rate very slowly (30 ° C./h) during heat treatment has been used. When the thickness is about 20 μm or more, there is a problem that it is almost impossible to obtain a healthy piezoelectric film after heat treatment even if the heat treatment process is controlled.

Therefore, the present inventors deposited the film by using aerosol deposition method using the raw material powder to which the organic material was added, and then heated the film on the hot plate to remove the organic matter present in the film, thereby forming nano-pores in the film, and the final film The nano-pores present in the film during the heat treatment solve the residual compressive stress accumulated in the film to produce a healthy PZT-based piezoelectric thick film having high bonding properties and high properties even after the final heat treatment. The present invention was completed by confirming that the piezoelectric thick film is thicker and has excellent electrical properties.

The present invention has been devised to solve the above problems of the prior art, and an object of the present invention is to provide a PZT-based piezoelectric thick film containing an organic material and having nano-pores.

In addition, after depositing the film through aerosol deposition method using PZT-based powder, by removing the organic material to create nano-pores in the film to relieve the residual compressive stress inside the film, excellent bonding to the substrate even after the second heat treatment The present invention provides a method for producing a PZT-based piezoelectric thick film having excellent characteristics.

In order to achieve the above object, the present invention provides a PZT-based piezoelectric thick film containing an organic material containing Pb (Zr _x Ti _1-x ) O ₃ , and having nano-pores.

Hereinafter, the present invention will be described in detail.

The present invention provides an PZT-based piezoelectric thick film containing an organic material containing Pb (Zr _x Ti _1-x ) O ₃ and having nano-pores.

PZT-based piezoelectric thick film according to the present invention is one of Pb-containing organic materials such as lead acetate [Pb (CH ₃ CO ₂ ) ₂ 3H ₂ O]), lead nitrate (Pb (NO ₃ ) ₂ ]) At least one of Zr-containing organics such as zirconium propoxide, zirconium ethoxide, zirconium butoxide, zirconium chloride, and titanium propoxide It is preferable to include at least one of Ti-containing organic substances such as propoxide, titanium ethoxide, titanium butoxide and titanium chloride.

In the present invention, in the PZT-based piezoelectric thick film containing an organic material containing Pb (Zr _x Ti _1-x ) O ₃ and having nano-pores, the composition of Pb, Zr and Ti is Pb (Zr _x Ti _1- x) O ₃ , wherein x is preferably 0.4 to 0.6. When x is less than 0.4 and exceeds 0.6, physical properties may deteriorate beyond the phase boundary (MPB) composition.

Further, the base composition may additionally include various oxides that act as hardeners or softeners, and a relaxed ferroelectric such as lead magnesium nitrate (PMN) or lead zinc niobate (PZN), and PZT or Pb ( Composite compounds with PbTiO ₃ ) may be added.

In the PZT piezoelectric thick film according to the present invention, the content of the organic material is preferably 1% to 30%. At this time, if the organic content is 30% or more, there is a problem in that the final density of the film is very low, and if it is less than 1%, there is a problem that less porosity is generated, thereby reducing the effect of reducing the residual compressive stress.

PZT-based piezoelectric thick film according to the present invention has nano-pores. The fine pores are generated at the sites where the above-mentioned organic matter is partially removed by heat treatment, and the content thereof is inversely proportional to the residual content of the organic matter. Therefore, the ratio of the nano-sized pores is preferably 30% ~ 1%. The nano-pores serve to reduce residual compressive stress in the thick film, thereby preventing cracks from occurring even when the thick film is increased. As a result, the problem of thick film thickness limitation pointed out as a problem of the conventional thick film can be solved.

In addition, the present invention comprises the steps of synthesizing the PZT-based raw material powder containing an organic material (step 1); Preparing a thick film by depositing the powder synthesized in step 1 on a substrate (step 2); Pyrolysing the organic material in the thick film prepared in step 2 (step 3); And heat treating the thick film pyrolyzed in step 3 (step 4).

Hereinafter, the manufacturing method will be described in detail step by step.

In the method for producing a PZT piezoelectric thick film according to the present invention, the step 1 contains an organic material containing Pb (Zr _x Ti _1-x ) O ₃ , and comprises a raw material powder of a PZT piezoelectric thick film having nano-pores. Synthesis step. Step 1 may be performed by steps 1a to 1c as follows.

Preparing a PZT-based precursor solution using a sol-gel method (step 1a); Preparing the precursor solution into a powder (step 1b); And controlling the organic matter content in the powder by heat-treating the dried powder (step 1c).

Step 1a is a step of preparing a precursor solution of a ceramic polymer precursor (preceramic polymer) that is an organic material containing a ceramic element by a conventional sol-gel method, a ceramic containing lead (Pb), zirconium (Zr), titanium (Ti) It involves dissolving the polymer precursor in a solvent to mix and then performing a hydration reaction. The organic material according to the present invention is one or more of Pb-containing organic materials such as lead acetate [Pb (CH ₃ CO ₂ ) ₂ 3H ₂ O]) and lead nitrate [Pb (NO ₃ ) ₂ ]). At least one of Zr-containing organics such as zirconium propoxide, zirconium ethoxide, zirconium butoxide, zirconium chloride, titanium propoxide ), An organic substance containing Pb, Zr and Ti containing at least one of Ti-containing organic substances such as titanium ethoxide, titanium butoxide, titanium chloride, and the like.

Step 1b is a step of drying and pulverizing the precursor solution of step 1a, removing the volatiles in the precursor solution to a powder state, and pulverizing the material to a uniform size, which includes milling the powder.

Step 1c is a step of thermally treating the powder of step 1b to thermally decompose the organic material contained in the powder, thereby controlling the organic content in the powder by heat treatment. It is preferable that the said heat processing is 200 degreeC-600 degreeC. At this time, if the heat treatment temperature exceeds 600 ℃, the content of the organic matter is too small, there is a problem that the nano-pores do not occur in the thick film, if less than 200 ℃, the content of the organic material in the raw material powder is too high to the pore in the final film Since the fraction is too high, there is a problem that the density and electrical properties of the film are very low.

It is preferable that the particle size of the PZT raw material powder synthesized by Step 1 is 0.3 μm to 10 μm in average particle diameter. Particles in the above range of about 10 μm or more cause a nonuniformity of the surface and thickness of the film and there is a problem in that a dense film is not formed when 0.3 μm or less.

Of step 1 above The composition of the organic material including Pb, Zr and Ti is Pb (Zr _x Ti _{1 -} x) O ₃ , wherein x is preferably 0.4 to 0.6. When x is less than 0.4 and exceeds 0.6, physical properties may deteriorate beyond the phase boundary (MPB) composition.

Furthermore, the organic material of step 1 may further include various oxides that act as hardeners or softeners, and may include a complex compound of a relaxed ferroelectric such as PMN or PZN and PZT or Pb (PbTiO ₃ ). can do.

Step 2 according to the present invention is a step of depositing the raw material powder of step 1 on a substrate at room temperature. At this time, the coating method used is preferably an aerosol deposition method. The organic material powder synthesized in step 1 is accelerated and deposited by using an aerosol deposition method, and oxygen, nitrogen, and air may be used to transfer the organic material powder, and the gas flow rate is in the range of 20 L / min to 50 L / min. Is preferred. At this time, there is a problem that it is difficult to obtain a dense film at a flow rate of less than 20 l / min, and there is a problem that the uniformity of the deposited film is lowered and the surface roughness is increased at a flow rate exceeding 50 l / min. In addition, the substrate may be silicon, alumina, sapphire, strontium titanate (SrTiO ₃ ), stainless steel, titanium and titanium alloys.

Step 3 according to the present invention is a step of removing the organic material in the thick film by first heat-treating the thick film deposited in the step 2. The organic material is thermally decomposed and removed through the first heat treatment of Step 3, and a plurality of nanometer-sized pores are formed in the place occupied by the removed organic material.

The first heat treatment temperature is preferably 300 ℃ ~ 500 ℃. The nano-pores are formed by the heat treatment, and as a result, the residual compressive stress in the film is reduced, so that a healthy film that is not separated from the substrate may be manufactured even after the second heat treatment.

Step 4 according to the present invention is a step of secondary heat treatment of the thick film after the first heat treatment in step 3. By the heat treatment of step 4 it is possible to increase the crystallinity of the first heat-treated thick film and to enhance the electrical properties. This heat treatment temperature is preferably 600 ℃ to 900 ℃. Through the secondary heat treatment, defects formed in the thick film during the deposition are removed, and as the crystallization and crystal grain growth of the thick film are made, a piezoelectric thick film having excellent characteristics is manufactured. In addition, even when the formed nanomicropores are thick films formed thickly by controlling the residual stress of the thick films, a stable thick film which does not occur with the substrate can be obtained.

Hereinafter, the present invention will be described in detail through examples. However, the following examples are only for exemplifying the present invention, and the contents of the present invention are not limited to the following examples.

Example 1 Preparation of Powder Containing Organic Matter

In order to prepare a PZT precursor solution using the sol-gel method,
A Pb precursor to prepare a solution obtained by dissolving a lead acetate _{(Pb acetate [Pb (CH 3} COO) 2 · 3H 2 O]) powder, 234 g of 2-methoxyethanol solvent, 563 g. In addition, 150 g of zirconium-n-propoxide (Zr-n-propoxide [Zr (OCH ₂ CH ₂ CH ₃ ) ₄ ]) as a Zr precursor, and titanium isopropoxide (Ti-i-propoxide Ti) as a titanium precursor. A solution in which 87 g of [OCH (CH ₃ ) ₂ ] ₄ ) was dissolved in 296 g of solvent propanol was prepared. The mixed solution of the two solutions was stirred for 1 hour, and then 44 g of the stirred solution was added to proceed with the hydration reaction for 24 hours. At this time, the composition of PZT in the precursor solution is Pb (Zr _0.52 Ti _0.48 ) O _{3, which} is known to exhibit the best electrical properties, and the precursor solution having a concentration of 0.45 M was prepared. The precursor solution was dried and pulverized by wet milling with ethanol to make the powder heat-treated at a temperature of 300 ° C. for aerosol deposition.

Example 2 Preparation of Powder Containing Organic Matter

Except that the heat treatment was carried out at 350 ℃ was prepared in the same manner as in Example 1.

Example 3 Preparation of Powder Containing Organic Matter

Except that the heat treatment was carried out at 450 ℃ was prepared in the same manner as in Example 1.

Figure 1 (a) and Table 1 is the result of the thermogravimetric analysis (Thermogravimetric analysis, TA Instruments, USA., SDT2960) of the dried powder of step 1b.

Temperature of powder (℃) 300 350 450 700 Weight of powder (%) 81.5 78.2 75.7 71.7

1 (a) and As shown in Table 1, the dried powder is 81.5% at 300 ℃, 78.2% at 350 ℃, 75.7% at 450 ℃, 71.7% at 700 ℃ it is found that the weight loss of the powder increases as the heat treatment temperature increases It can be seen that the organic matter contained in the dried powder is decomposed by heat, and thus the amount of organic matter removed is changed depending on the temperature. Therefore, it can be seen that control of the organic matter content in the powder is possible by controlling the powder heat treatment temperature.

Thus, in the present embodiment, the powder heat treatment is carried out at a temperature of 300 ℃ (Example 1), 350 ℃ (Example 2), 450 ℃ (Example 3), and then carried out thermogravimetric analysis of the organic content of each powder It is shown in Figure 1 (b).

As shown in (b) of FIG. 1, Example 1 includes 12 wt%, Example 2 includes 8 wt%, and Example 3 includes 5 wt% of organic matter, and the organic matter in the powder through the heat treatment of step 1c. It was confirmed that the content can be adjusted.

Figure 2 (a) is the result of measuring the size of the powder prepared using the particle size analyzer (HELOS / BF, Sympatec GmbH, Germany) of Example 3, Figure 2 (b) using a scanning electron microscope This is the result of analyzing the actual form and size of the powder. As shown in (a) of Figure 2 it can be seen that Example 3 has a wide particle size distribution with a size of 0.3 ㎛ ~ 10 ㎛. In addition, as shown in (b) of Figure 2, the powder particles have an irregular shape, it can be seen that the particle size distribution is similar to the particle size analysis results.

Example 4 Preparation of PZT-Based Piezoelectric Thick Film Containing Organic Matter and Having Nano Micropores

Using the final powder of Example 3, a film having a thickness of about 10 μm to 100 μm was prepared by an aerosol deposition method with a 5 mm × 12 mm area. Subsequently, the organic film in the deposited thick film was completely removed through a first heat treatment in which the deposited thick film was heated at 440 ° C. for 1 hour using a hot plate, and the final PZT system was subjected to a second heat treatment at 700 ° C. for 1 hour. A piezoelectric thick film was obtained.

Comparative Example 1 Preparation of PZT Thick Film Containing No Organic Matter

Solid phase reaction was used to prepare PZT powder containing no organic matter. PbO (68.5 g), ZrO ₂ (19.7 g), TiO ₂ (11.8 g) powders were mixed and dried through a ball mill, and then calcined at 850 ° C. for 2 hours to synthesize PZT powders. The powder was again milled to a size suitable for aerosol deposition to produce a final PZT powder. Using the powder, a PZT film having a thickness of 10 μm to 100 μm was formed on a Pt / Ti / SiO ₂ / Si substrate on a Pt / Ti / SiO ₂ / Si substrate with a thickness of 5 mm × 12 mm, and the film was used at an electric furnace for 1 hour at 700 ° C. After the second heat treatment to obtain a final PZT film.

3 is a photograph of Example 4 at 100 μm and Comparative Example 1 at 20 μm on a Pt / Ti / SiO ₂ / Si substrate. As shown in (a) of FIG. 3, the film is sound immediately after the powder of Comparative Example 1 is deposited on the substrate during the formation of Comparative Example 1, but after performing the second heat treatment at 700 ° C., the thick film thickness When the thickness is 20 µm or more, it can be seen that the film is damaged while separation between the substrates occurs. On the other hand, in the thick film of Example 3 shown in (b) of FIG. 3 at 100 μm, no separation between the film and the substrate or cracks were observed in the film even after the second heat treatment, thereby ensuring that the PZT-based piezoelectric thick film was soundly formed. These results showed the same results in the entire thick film formed, respectively.

Figure 4 shows the microstructure of the surface of Example 4 analyzed by scanning electron microscopy. (A) is a cross-sectional photograph of a thick film deposited at 20 탆, respectively, and (b) is a photograph of its surface. In addition, (c) is a cross-sectional photograph of a thick film formed in 100 ㎛ and (d) is a surface photograph thereof. As shown in (a) and (c) of FIG. 4, all thick films having different thicknesses have a uniform film thickness, and it can be seen that cracking or separation of the film does not proceed even after the heat treatment. In addition, as shown in (b) and (d) of Figure 4, even if the film thickness is thickened to 100 ㎛ almost no change in the size of the particles in the film, it is confirmed that the particles of uniform size around about 100 nm Can be.

FIG. 5 is a photograph of Example 4 deposited at 20 μm, followed by scanning electron microscopy of the microstructure before and after the first and second heat treatments. FIG. As shown in FIG. 5, while the thick film immediately after depositing the thick film shows a dense structure with little pores, the organic material in the thick film (b) that is primarily heat treated is removed. As a result, a plurality of nano-pores were generated, and the pores were maintained in the thick film (FIG. 5C) after the second heat treatment. Thus, the pores generated in the film observed in (b) serves to relieve the residual compressive stress accumulated in the film, so that the film remains healthy after the second heat treatment.

FIG. 6 shows X-ray diffraction analysis results (D-MAX 2200, Rigaku Co., Japan) for the films deposited using Example 3 and the films after the first and second heat treatment. The analysis can provide information about the phase change of the deposited film in the first and second heat treatment steps. In the case of the deposited film, the width of the peak is wide and the strength is low, which is typical of the film produced by the aerosol deposition method. When the deposited film is subjected to the first heat treatment, the peak intensity of the PZT crystal phases including the PZT (110) phase around 31 ° C. is increased and the peak width is reduced. It means that it is progressed. In the case of the second heat-treated film, the peak intensity was higher and the peak width was also markedly reduced. This is because the crystallization proceeded more and the crystal grains grew as the heat treatment was performed at a temperature higher than the first heat treatment temperature. do. In addition, a second phase such as a pyrochlore phase, which is generally known to degrade the properties of the PZT film, is not observed at all in the secondary heat-treated film. The PZT thick film is excellent because it is made of pure PZT crystal phase having a perovskite structure. It can exhibit electrical characteristics.

Experimental Example 1 Measurement of Electrical Properties of PZT Thick Films Containing Organics and PZT Thick Films Containing Organics

Ferroelectric properties of the thick films prepared in Examples 1, 2 and 3 by the method of Example 4 and the thick films prepared in Comparative Example 1 with a 10 μm thickness (Precision LC, Radiant Technologies Inc., USA ) Is shown in Figure 7 and Table 2. Figure 7 (a) is a graph showing the measurement of the polarization vs. the electric field strength of the Examples and Comparative Examples and Figure 7 (b) is a measurement of the change in the residual polarization and constant field values of the Examples and Comparative Examples It is a graph (the field value refers to the value on the left axis and the residual polarization refers to the value on the right axis). In the film having a thickness of 20 µm or more in Comparative Example 1, since the film was damaged after the heat treatment and the electrical properties could not be measured, the characteristic value of the thick film having the thickness of 10 µm was shown.

Example 1 Example 2 Example 3 Comparative Example 1 Residual Polarization (μC / ㎠) 17 16.5 22.3 12.8 Constant field (kV / cm) 67 53.5 48.5 32 Non-dielectric constant 523 549 635 995 Dielectric loss 0.080 0.022 0.020 0.018

As shown in FIG. 7 and Table 2, hysteresis curves showing typical ferroelectric properties were observed for all films.

 From (b) of FIG. 7, in the case of a film deposited using a powder containing an organic substance, each residual polarization is shown in Comparative Example 1 (12.8), Example 2 (16.5), Example 1 (17.0), and Example 3 In order of (22.3). In particular, the residual polarization value (22.3) of Example 3 was increased by about 70% compared to Comparative Example 1 (12.8) to confirm the excellent ferroelectric properties. In addition, the respective electric field values decreased in the order of Example 1 (67.0), Example 2 (53.5), and Example 3 (48.5), and showed excellent ferroelectric properties due to the change of porosity in the film according to the organic content.

8 and Table 2 show and measure the specific dielectric constant and dielectric loss of Example 1, Example 2, Example 3 and Comparative Example 1. As shown in Fig. 8 and Table 2, the dielectric constant is increased to Example 1 (523), Example 2 (549), and Example 3 (635), respectively, and the dielectric loss is Example 1 (0.080) and practice. Reduced to Example 2 (0.022), Example 3 (0.020), the higher the pyrolysis temperature, the higher the specific dielectric constant, the lower the dielectric loss was confirmed excellent electrical properties.

As described above, when the thick film was prepared by the aerosol deposition method using the raw material powder containing the organic material and subjected to the first heat treatment and the second heat treatment, the thick film having a thickness of 100 μm was not separated from the substrate after the heat treatment. It remained healthy and no cracking was observed in the thick film. In addition, the PZT thick film prepared by the above method was confirmed to have excellent electrical properties.

The present invention is a PZT-based piezoelectric thick film containing an organic material and nano-pores, by depositing a thick film using PZT powder containing an organic material as a raw material powder, and then forming a nano-pores in the thick film through the first heat treatment By performing the second heat treatment to improve the electrical characteristics, it is possible to produce a healthy PZT-based piezoelectric thick film that does not separate from the substrate and does not crack even when the thick film thickness is increased. In particular, the PZT-based piezoelectric thick film prepared by the present invention has a shorter film deposition time than a conventional thick film, can be produced at a high heat treatment rate and a cooling rate, and has a superior thickness and the excellent electrical properties and stability. Therefore, the PZT-based piezoelectric thick film according to the present invention can be usefully used for sensors and actuators having high sensitivity, high power, stability and fast response speed.

Claims (23)

A PZT-based piezoelectric thick film containing an organic material containing Pb (Zr _x Ti _1-x ) O ₃ and having nano-pores. The organic material of claim 1, wherein the organic material comprises at least one Pb-containing organic material selected from the group consisting of lead acetate (Pb (CH ₃ CO ₂ ) ₂ 3H ₂ O) and lead nitrate (Pb (NO ₃ ) ₂ ); One or more Zr-containing organics selected from the group consisting of zirconium propoxide, zirconium ethoxide, zirconium butoxide and zirconium chloride; And at least one Ti-containing organic material selected from the group consisting of titanium propoxide, titanium ethoxide, titanium butoxide and titanium chloride. delete The PZT-based piezoelectric thick film according to claim 1, wherein x is in a range of 0.4 to 0.6. The PZT-based piezoelectric thick film according to claim 1, wherein the organic material further comprises an oxide serving as a reinforcing agent or a softening agent. The PZT-based piezoelectric thick film according to claim 1, wherein the organic material further comprises a relaxed ferroelectric of PMN or PZN. The PZT-based piezoelectric thick film according to claim 1, wherein the organic content is 1% to 30%. The PZT-based piezoelectric thick film of claim 1, wherein a content of the nano-sized pores is 30% to 1%. Synthesizing a PZT-based raw material powder containing an organic material containing Pb (Zr _x Ti _1-x ) O ₃ (step 1); Preparing a thick film by depositing the powder synthesized in step 1 on a substrate (step 2); Primary heat treatment of the thick film prepared in step 2 (step 3); And Secondary heat treatment of the thick film pyrolyzed in step 3 (step 4) A method for producing a PZT-based piezoelectric thick film according to claim 1, comprising a. The method of claim 9, wherein step 1 Preparing a PZT-based precursor solution using a sol-gel method (step 1a); Drying the precursor solution to form a powder (step 1b); And Heat-treating the dried powder to adjust the content of organic matter in the powder (step 1c) Method for producing a PZT-based piezoelectric thick film comprising a. The organic material of claim 9 or 10, wherein the organic material is at least one Pb-containing organic material selected from the group consisting of lead acetate (Pb (CH ₃ CO ₂ ) ₂ 3H ₂ O) and lead nitrate (Pb (NO ₃ ) ₂ ). ; One or more Zr-containing organics selected from the group consisting of zirconium propoxide, zirconium ethoxide, zirconium butoxide and zirconium chloride; And at least one Ti-containing organic material selected from the group consisting of titanium propoxide, titanium ethoxide, titanium butoxide and titanium chloride. The method of claim 10, wherein the heat treatment of step 1c is in the range of 200 ° C to 600 ° C. The method for producing a PZT-based piezoelectric thick film according to claim 9 or 10, wherein the average particle diameter of the synthesized PZT-based raw material powder is 0.3 µm to 10 µm. delete The method for producing a PZT-based piezoelectric thick film according to claim 9 or 10, wherein x is in a range of 0.4 to 0.6. The method of manufacturing a PZT piezoelectric thick film according to claim 9 or 10, wherein the organic material further comprises an oxide serving as a reinforcing agent or a softening agent. The method of manufacturing a PZT piezoelectric thick film according to claim 9 or 10, wherein the organic material further comprises a complex compound of PMN or PZN with a relaxed ferroelectric. The method of manufacturing a PZT piezoelectric thick film according to claim 9 or 10, wherein the organic content is 1% to 30%. 10. The method of claim 9, wherein the deposition method of Step 2 is an aerosol deposition method. 20. The method for manufacturing a PZT-based piezoelectric thick film according to claim 19, wherein a gas flow rate in the aerosol deposition method is 20 L / min to 50 L / min. 10. The PZT piezoelectric body according to claim 9, wherein the substrate of step 2 is any one selected from the group consisting of silicon, alumina, sapphire, strontium titanate (SrTiO ₃ ), stainless steel, titanium, and a titanium alloy. Thick film production method. 10. The method of claim 9, wherein the first heat treatment temperature of step 3 is in the range of 300 ° C to 500 ° C. 10. The method of claim 9, wherein the secondary heat treatment temperature of step 4 is in the range of 600 ° C to 900 ° C.

Images