CN103193482B - A kind of lead zirconate titanate thick film and preparation method thereof - Google Patents

Abstract

The invention discloses a method for preparing a lead zirconate titanate thick film, which is used for forming a lead zirconate titanate thick film on a titanium sheet. The method specifically includes: configuring a precursor solution in an autoclave liner; solution, and put the autoclave into a magnetic stirrer for magnetic stirring; finally, take out the titanium sheet to realize the reaction on the titanium sheet to form a lead zirconate titanate (PZT) thick film. The invention also discloses a lead zirconate titanate thick film prepared by the method. The preparation process of the present invention is completed once in the liquid phase without post-heat treatment, avoiding the interdiffusion of components between the substrate and the thick film caused by excessive temperature, and the thickness of the film can be controlled by repeating the number of crystallization processes, which is simple and feasible. In addition, the prepared film is not controlled by the size and shape of the substrate. The PZT thick film can be prepared on the surface of a three-dimensional structure, and the prepared PZT thick film has a uniform surface and a composition near the quasi-isomorphic phase boundary.

Description

A kind of lead zirconate titanate thick film and preparation method thereof

technical field

The invention belongs to the field of ceramic thick film preparation, in particular to a method for preparing a lead zirconate titanate (PZT) thick film.

Background technique

Lead zirconate titanate (PZT) material exhibits excellent piezoelectric, ferroelectric, and dielectric properties at the quasi-isomorphic phase boundary (Zr/Ti=52/48), and PZT thick film (generally refers to PZT film with a thickness greater than 1 μm) ) devices not only have low operating voltage, high frequency of use, and are compatible with semiconductor integrated circuits, but also have similar electrical properties to piezoelectric bulk devices. Therefore, in recent years, PZT thick films have been used in underwater acoustics, medical ultrasonic diagnosis, MEMS and other fields have been widely used.

The commonly used preparation methods of lead zirconate titanate (PZT) generally include sol-gel method, screen printing method, casting method, electrophoretic deposition method and hydrothermal method. Among them, the sol-gel method is often used, but when using this method, due to the large amount of organic matter, it is easy to generate pores, the probability of cracking of the prepared PZT thick film is relatively high, and the lower temperature is prone to produce pyrochlore heterophase, the prepared thick film The surface of the film is rough and the density is not good enough. The screen printing method is the most mature technology, but it is difficult to mix the slurry evenly, and the post-calcination temperature is higher than 850°C, which will lead to the interdiffusion of the thick film and the substrate and the volatilization of PbO, which will affect the electrical properties. The tape casting method is not compatible with MEMS, and the thick film needs to be bonded to the substrate. The process is relatively complicated and the reliability is not high. The disadvantage of the electrophoretic deposition method is that the efficiency is low when the electric field strength is low, and the prepared film is thinner, and the high electric field strength easily leads to rough cracking of the film layer, and the electrode is also prone to other electrochemical reactions.

At present, the defects caused by the above-mentioned methods can be better overcome by using the hydrothermal method. Generally, the method of preparing PZT thick film by hydrothermal method is usually heated in an oven. Since the precursor solution for preparing PZT thick film is a suspension, when the oven heating is not introduced into the stirring function, the solution in the autoclave will be stratified, resulting in The PZT thick film is not uniform and the ratio of zirconium and titanium deviates from Zr/Ti=52/48, so that the composition of the prepared PZT thick film deviates from the quasi-isomorphic phase boundary, which greatly affects the electrical properties of the prepared PZT thick film.

Contents of the invention

One of the purposes of the present invention is to provide a method for preparing a lead zirconate titanate (PZT) thick film, the process is simple, the prepared PZT thick film has a uniform surface, its composition is at the quasi-isomorphic phase boundary, and its electrical properties are relatively large. improve.

The method of the present invention not only can provide the high temperature and high pressure conditions for preparing PZT thick film by the hydrothermal method by utilizing the heating method of the collector type constant temperature heating magnetic stirrer, but also ensures the uniformity of the solution in the reaction process by using its own magnetic stirring function , to a great extent solved the problem of uneven surface and composition deviation of quasi-isomorphic phase boundary of PZT thick film prepared by oven heating.

The technical scheme adopted to realize the object of the present invention is as follows:

A method for preparing a lead zirconate titanate thick film, which is used to generate a lead zirconate titanate thick film on a titanium sheet, is characterized in that the method specifically includes:

Configure the precursor solution in the autoclave liner;

The titanium sheet is vertically immersed in the precursor solution, and the autoclave is placed in a magnetic stirrer for magnetic stirring;

Finally, the titanium sheet is taken out, and then a thick film of lead zirconate titanate (PZT) can be formed on the titanium sheet.

As a further preference of the present invention, the precursor solution is prepared from lead nitrate, zirconium oxychloride, titanium tetrachloride and potassium hydroxide.

As a further preference of the present invention, the titanium tetrachloride can be replaced by titanium dioxide or butyl phthalate.

As a further preference of the present invention, the molar ratio of Zr/Ti in the precursor solution is preferably 52/48.

As a further preference of the present invention, the magnetic stirrer is filled with silicone oil, and the autoclave is submerged in the silicone oil and stirred by magnetic heating to carry out the reaction.

As a further preference of the present invention, the heating reaction temperature is 110° C. to 130° C., and the reaction time may be 24 hours.

As a further preference of the present invention, the titanium sheet is vertically immersed in the precursor solution after being fixed by a shrapnel arranged in the inner tank of the autoclave, and the shrapnel is fixed in the inner tank by bending at both ends.

As a further preference of the present invention, the shrapnel is made of titanium sheet,

As a further preference of the present invention, before the titanium sheet is immersed in the precursor solution, it is firstly cleaned and pretreated to remove surface pollutants.

Another object of the present invention is to provide a lead zirconate titanate thick film prepared by the above preparation method.

The surface of the PZT thick film prepared by the method of the invention is uniform, and the composition is at the quasi-isotype phase boundary, thereby greatly improving its electrical performance. The PZT thick film prepared by this method has the following advantages:

1. The preparation process is completed in the liquid phase at one time, without post-heat treatment.

2. The temperature used is low (below 200°C), which avoids interdiffusion of components between the substrate and the thick film due to excessive temperature.

3. The thickness of the film can be controlled by repeating the crystallization process times, which is simple and feasible.

4. The prepared film is not controlled by the size and shape of the substrate, and the PZT thick film can be prepared on the surface of the three-dimensional structure.

5. The prepared film has piezoelectric properties without polarization.

6. The surface of the prepared PZT thick film is uniform, and the composition is near the quasi-isomorphic phase boundary (Zr/Ti=52/48). 7. The equipment is simple and the cost is low.

Description of drawings

Figure 1 is a schematic diagram of the interior of an autoclave according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of a system for preparing a PZT thick film by an oil bath hydrothermal method according to an embodiment of the present invention.

Fig. 3 is the XRD phase diagram of the PZT thick film of the embodiment of the present invention.

Fig. 4 is a SEM image of the PZT thick film of the embodiment of the present invention.

In the figure, 1 is the stainless steel shell of the autoclave, 2 is the Teflon liner, 3 is the titanium sheet, 4 is the precursor solution, 5 is the magnet, 6 is the temperature sensor, 7 is the autoclave, 8 is the silicone oil, and 9 is the heating wire.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

According to a preferred embodiment of the present invention, the preparation method of PZT thick film comprises following specific steps:

1. Pretreatment of Ti slices

First, cut the titanium sheet into a certain size (the area can be adjusted according to the needs, preferably 2cm×1cm in this example, other sizes can also be used), then the Ti sheet is mechanically polished to remove the corroded part of the surface, and deionized Rinse with water, then perform alcohol ultrasound (the time is preferably 10min), rinse again with deionized water and perform acetone ultrasound (for example, the time can be 10min), then perform alcohol ultrasound again (the time is preferably 10min), and finally use deionized water Rinse well and dry for later use.

2. Preparation of precursor solution

In this embodiment, the precursor solution is composed of lead nitrate Pb(NO ₃ ) ₂ , zirconium oxychloride ZrClO ₂ .8H ₂ O, titanium tetrachloride TiCl ₄ and potassium hydroxide KOH. The above-mentioned raw materials are preferably directly added to the polytetrafluoroethylene liner of the autoclave to avoid secondary pollution.

First, weigh lead nitrate Pb(NO ₃ ) ₂ and zirconium oxychloride ZrClO ₂ .8H ₂ O according to the molar ratio Zr/Ti=52/48, add deionized water after mixing and stir for a certain period of time (such as 20min), then Add TiCl ₄ aqueous solution and stir (the time is preferably 10min), then weigh a certain amount of KOH and add it slowly, and finally stir the mixed solution for a certain period of time (for example, 40min) to form a precursor solution. In this embodiment, the consumption of each component can be adjusted according to the actual size of the autoclave. In addition, in this embodiment, the filling degree of the autoclave is preferably 80%, the molar ratio of zirconium and titanium ions is preferably Zr/Ti=52/48, and other ratios can also be used, and the KOH concentration is preferably 4 mol/l.

Based on the above conditions, the precursor solution for preparing PZT thick film was prepared.

In this embodiment, the concentration of KOH can be selected as 2mol/l～6mol/l, but the PZT crystal phase prepared with a concentration of 4mol/l is the best, because the reaction is slower if the concentration is too low, which is not conducive to the reaction. Occurrence and too high a concentration is easy to generate other impurities.

The molar ratio of Zr/Ti can generate PZT in the range of 90/10～10/90, but the ratio of Zr/Ti of the precursor in this embodiment is preferably 52/48, and the prepared PZT thick film sample Zr/Ti corresponds to this ratio.

The _TiCl in the above-mentioned embodiment can also be TiO ₂ and butyl phthalate, but the surface morphology of the PZT thick film prepared with TiO ₂ and butyl phthalate is irregular, while the surface morphology of the PZT thick film prepared with _TiCl is crystalline. Uniform particle size, obvious cubic particles, and good surface morphology. Therefore, TiCl ₄ is preferred as the titanium source in this embodiment.

3. Put the Ti sheet and magnet into the autoclave

First, use a narrow Ti sheet (the width can be adjusted as needed, such as 0.2-0.5 cm, preferably 0.3 cm in this embodiment) to make a shrapnel, and fix the titanium sheet cleaned in step 1 on the shrapnel. Then, put the titanium sheet with the shrapnel into the inner tank of the autoclave containing the precursor solution prepared according to step 2, use the support of the shrapnel to keep the Ti sheet vertically submerged in the solution, and put the magnet at the bottom of the autoclave , to react. As shown in Figure 1.

During the reaction process, the Ti sheet should be placed vertically to avoid contact with the inner wall of the autoclave, causing the reactants in the precursor solution to be deposited unevenly on the Ti sheet. Membrane formation.

In this embodiment, the autoclave is placed in a heat-collecting constant temperature heating magnetic stirrer to ensure that the autoclave is submerged in silicone oil, as shown in FIG. 2 . The reaction conditions can preferably set the reaction temperature at 130° C., the reaction time at 24 h, and adjust the rotation speed to carry out the reaction.

In this embodiment, the PZT thick film can be prepared at a reaction temperature of 110°C to 130°C, preferably 130°C, a higher temperature can accelerate the reaction process

4. Clean PZT thick film

After the reaction, a thick PZT film can be formed. When the autoclave is naturally cooled to room temperature, the PZT thick film is taken out from the autoclave, cleaned with deionized water, and dried in an oven.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (7)

1. a hydrothermal preparing process for lead zirconate titanate thick film, for generating lead zirconate titanate thick film in titanium sheet, it is characterized in that, the method specifically comprises:

Precursor aqueous solution is configured in autoclave inner bag;

Cleaned described titanium sheet is dipped vertically in described precursor aqueous solution, and described autoclave is put into magnetic stirring apparatus carries out magnetic agitation;

Finally, take out titanium sheet, reaction in titanium sheet can be realized and generate lead zirconate titanate (PZT) thick film;

Wherein, be filled with silicone oil in described magnetic stirring apparatus, described autoclave to be submerged in silicone oil and is reacted by magnetic agitation under certain heating-up temperature, and heating reaction temperature is 110 DEG C ~ 130 DEG C;

Described titanium sheet is dipped vertically in described precursor aqueous solution after being fixed by the shell fragment be arranged in autoclave inner bag, and this shell fragment is fixed in above-mentioned inner bag by the bending of two ends.

2. the hydrothermal preparing process of a kind of lead zirconate titanate thick film according to claim 1, wherein, described precursor aqueous solution is formulated by plumbi nitras, zirconium oxychloride, titanium tetrachloride and potassium hydroxide.

3. the hydrothermal preparing process of a kind of lead zirconate titanate thick film according to claim 2, wherein, described titanium tetrachloride can be replaced titanium dioxide or Butyl Phthalate.

4. the hydrothermal preparing process of a kind of lead zirconate titanate thick film according to any one of claim 1-3, wherein, in described precursor aqueous solution, mole value of Zr/Ti is 90/10 ~ 10/90.

5. the hydrothermal preparing process of a kind of lead zirconate titanate thick film according to any one of claim 1-3, wherein, in described precursor aqueous solution, mole value of Zr/Ti is 52/48.

6. the hydrothermal preparing process of a kind of lead zirconate titanate thick film according to claim 1, wherein, described shell fragment is made up of titanium sheet.

7. the hydrothermal preparing process of a kind of lead zirconate titanate thick film according to any one of claim 1-3, wherein, described titanium sheet, before immersion precursor aqueous solution, first carries out cleaning pretreatment, to remove surface contaminant.