JPS61158821A - Production of lead titanate crystallite - Google Patents

Abstract

PURPOSE:In wet synthesis method in an alkali aqueous solution, to obtain the titled crystallite of perovskite type having high uniformity of composition and high purity, and a little lattice strain without requiring heat treatment, by specifying pH and the reaction temperature. CONSTITUTION:A soluble Ti compound or its hydrolyzate is reacted with a lead compound in an aqueous solution at >= 12.7pH at >= 175 deg.C. Consequently, lead titanate crystallite of perovskite phase can be selectively synthesized. The prepared crystallite is extremely uniform cubic granules, and has improved orientation. The crystallite has high stoichiometric properties during synthesis and has high purity, so it has improved characteristics and a little lattice strain without carrying out heat treatment particularly. Consequently, it is considered to be extremely advantageous for piezoelectric characteristics and pyroelectric characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing perovskite-type lead titanate microcrystals that can be used as ferroelectric, piezoelectric, or pyroelectric materials.

[Conventional technology]

In the field of dielectrics and ceramics, new synthesis methods for dielectric oxide fine particles, which serve as raw materials, are being developed in response to the miniaturization of electronic components and the diversification of applications.

For example, in multilayer ceramic capacitors, it is necessary to reduce the thickness of the ceramic layer in order to increase the capacitance as well as reduce the size and weight, and making the dielectric oxide, which is the raw material, finer particles is an important issue. Furthermore, from the viewpoint of the withstand voltage of the capacitor, abnormal grain growth and generation of non-uniform particles during the sintering stage are undesirable, and there is an urgent need to develop a method for synthesizing uniform fine particles.

For similar reasons, there is a demand for the development of uniform atomization technology for piezoelectric actuators, bimorphs, pyroelectric infrared sensors, etc. that use piezoelectric or pyroelectric materials, and especially when considering the use in sensors. In this case, if an oriented ceramic can be produced, it is considered to be advantageous in terms of manufacturing costs, etc., compared to an oriented thin film produced by high-frequency sputtering.

On the other hand, the dielectric oxide that is the raw material for dielectric ceramics is
Lead titanate is widely used because it has many excellent properties. Then, this lead titanate (P b T i 07
) are generally lead oxide (PbO) and titanium oxide (TiO
□), and after grinding and mixing with a ball mill, 800
It is synthesized by pre-calcining at ~1000°C, pulverizing again until uniform, and then performing main firing.

By the way, when lead titanate fine particles are synthesized by such a method, evaporation of PbO becomes a major problem. That is, as the temperature during the above-mentioned pre-calcination is higher, the amount of evaporation of PbO increases exponentially, and there is a possibility that the composition of the obtained lead titanate fine particles may change. Therefore, in order to avoid this, it is necessary to take considerable measures during heat treatment, such as performing firing in a PBO atmosphere. Alternatively, in order to suppress the evaporation of PbO, it may be possible to lower the temperature of the pre-calcination and then perform the main firing, but in this case, a considerable amount of unreacted PBO may remain at the end of the above-mentioned pre-calcination. ,
There is a risk that this unreacted PbO may vaporize during the main firing stage, so atmosphere control is also required here. For this reason, lead titanate fine particles obtained by the solid phase reaction method using heat treatment as described above,
Δ site defects in perovskite structures such as Pb and -ST i Ol are likely to occur, and there is a high possibility that this non-stoichiometry will adversely affect piezoelectric properties, pyroelectric properties, etc. Further, even if it is assumed that a product with high stoichiometry can be obtained by high-temperature heat treatment, the sinterability will deteriorate as long as the raw material cleavage procedure as described above is used.

This is because lead titanate has the highest crystal anisotropy among those with a perovskite structure, that is, it has a large square strain, so the coefficient of thermal expansion in a specific direction is significantly different.
This is because cracks may occur when the temperature is lowered from a high temperature. Furthermore, in order to avoid this, it is conceivable to add various additives to improve the sinterability, but in this case, problems with piezoelectric properties arise. In other words, lead titanate has the advantage that the electromechanical coupling coefficient for longitudinal waves is larger than that for transverse waves, and is effectively used in areas that cannot be reached with other piezoelectric materials. It is quite conceivable that the addition of this material will degrade its properties.

Therefore, for the reasons mentioned above, there are almost no examples of application of lead titanate in its pure form to dielectric ceramics using the solid phase reaction method, and it is difficult to obtain either one of the contradictory properties of piezoelectric properties and sinterability. The reality is that we are putting a lot of emphasis on it and putting it into practical use.

On the other hand, in order to achieve practical use as a raw material for transparent ceramics, additives for capacitors, materials for low-temperature sintering, etc., we have to deal with the problem of non-uniformity of particles, lack of activity, etc. in the solid phase reaction method.
Attempts have been made to improve the contamination of impurities and obtain uniform fine particles.

For example, Japanese Patent Publication No. 51-2080 discloses a wet synthesis method in which salts of A ions and B ions in A B O3 of a perovskite structure to be synthesized are reacted at boiling in an alkaline aqueous solution. However, in this method, [A ion]/[B ion concentration ratio,
Since the ion concentration ratio during synthesis is not 1, the composition tends to fluctuate, and the synthesized product is amorphous and hydrated. Therefore, heat treatment at 300 to 400°C is necessary to obtain crystalline particles. Furthermore, decantation is performed to remove excess pbcβ, which becomes an impurity during synthesis, but it is difficult to completely remove this PbC1.

Alternatively, the oxalate method and the Shella acid ethanol method are known as other methods, but in the former, the solubility of oxalate may differ depending on the type of metal ion, and the pH range of precipitation may differ. It is difficult to obtain one with a uniform composition. Furthermore, since an organic compound called oxalate is used, there are many problems in terms of manufacturing cost and productivity. Furthermore, in the latter case, although compositional uniformity has been improved to some extent, problems remain in terms of manufacturing cost, productivity, etc.

Furthermore, the so-called metal alkoxide method involves synthesizing an organometallic compound represented by the general formula M(OR), synthesizing from it a composite alkoxide represented by the general formula M-ML(OR)m, and then hydrolyzing it. has also been proposed, but it has many problems in terms of manufacturing costs and productivity. Further, although the obtained precipitate is of high purity, it is amorphous and requires heat treatment at about 400°C.

[Problem that the invention seeks to solve]

Thus, using conventional synthesis methods, it is difficult to synthesize crystalline lead titanate microcrystals from the liquid phase without heat treatment.
It has been difficult to obtain lead titanate microcrystals with high uniformity and purity.

Therefore, the present invention has been proposed in view of the actual situation in the technical field as described above. The purpose of the present invention is to provide a method for producing lead titanate microcrystals that can produce lead titanate microcrystals.

[Means for solving problems]

The inventors of the present invention sought to develop a synthesis method capable of wet-synthesizing crystalline lead titanate fine particles of high purity, uniformity, and low lattice strain without heat treatment, and as a result of long-term research, they found that the pH and By setting the synthesis temperature to a predetermined value, it is possible to synthesize perovskite-type lead titanate microcrystals, pyrochlore-type lead titanate microcrystals, or acicular lead titanate microcrystals having a new crystal phase. I discovered that.

The present invention was completed based on such findings, and consists of combining a soluble titanium compound or its hydrolysis product and a lead compound in an aqueous solution with a T)HI of 3.7 or higher and an lR
It is characterized in that the reaction is carried out at a temperature of 175°C or higher.

In the present invention, in order to create lead titanate microcrystals, a soluble titanium compound such as titanium tetrachloride (T i C1,) or its hydrolysis product, and a hydrolysis product of a lead compound or its hydrolysis product are used. Mix with water-soluble salt,
K'', N
It is sufficient to completely remove alkaline cations such as a'' and anions such as C7!-, and then filter and dry.

Here, the pH and reaction temperature during the above reaction are important,
Depending on the pH and reaction temperature, lead titanate microcrystals in the perovskite phase (hereinafter referred to as PE phase), pyrochlore phase (hereinafter referred to as P and Y phases), or new acicular crystalline phase (hereinafter referred to as PE phase) can be formed. PX phase) lead titanate microcrystals are formed. The present inventors conducted repeated experiments and determined that the pH during the above reaction was
We attempted to create a phase diagram of lead titanate microcrystals obtained by varying the reaction temperature. The results are shown in Figure 1. From this figure 1,
It was found that the PY phase is stable in the low-alkali high temperature range to the high-alkali low temperature range, the PR phase is stable only in the high-alkali high temperature range, and furthermore, the PX phase is formed only within a specific range. In Figure 1, the numbers in parentheses represent slightly generated by-products, and 8M represents amorphous.
Represents the state of lead titanate.

That is, to create PE phase lead titanate microcrystals,
It is necessary to set the pH to 12.7 or higher and the reaction temperature to 175°C or higher, and preferably to set the pH to 13.1 or higher and the reaction temperature to 190°C or higher. By setting within such a range, PE phase lead titanate microcrystals are selectively generated. In this case, a reaction time of less than 1 hour is sufficient. The PE phase lead titanate microcrystals obtained here are crystalline precipitates that contain almost no water, and the particle size is 6.
They are very uniform dice-shaped crystal fine particles with a size of ~8μ. In particular, the dice-shaped crystal planes are (hoe) and (00I
It is also possible to create a highly oriented sheet by mixing an appropriate resin binder and performing so-called casting. Moreover, it is also possible to create a three-sided disk by pressure molding, and it is expected to be used as a raw material powder that can be subjected to highly oriented firing. Furthermore, the particle size of the lead titanate microcrystals of the PE phase obtained can be changed by changing the stirring speed during the reaction or by slightly changing the pH, and the stoichiometry can also be changed. expensive. Furthermore, the PE phase obtained here is
By performing heat treatment, the distortion of the lattice decreases as the temperature increases, and in particular, the lattice distortion of the C axis is extremely small, which is advantageous in terms of piezoelectric and pyroelectric properties.

On the other hand, pH 12.1 or higher and reaction temperature 1°0~
190°C, preferably pH 13.0 or higher, reaction temperature 11
By setting the temperature to 110 to 175°C, PY phase lead titanate microcrystals are selectively generated. Although a reaction time of one hour or less is sufficient, the longer the reaction time, the better the crystallinity of the obtained PY phase. The lead titanate microcrystals of the PY phase obtained here also have extremely high stoichiometry, and the particle size is less than 0.2μ, which is one order of magnitude larger than that obtained by conventional solid-phase reaction methods. Because of its small size, it has high utility value as a base material or additive for capacitor materials, or as a raw material for high-density sintered bodies.

Also, pH 11,2-13. When the O1 reaction degree is set to 145°C or higher, PX phase lead titanate microcrystals are generated, especially when the pH is 11.5 to 12.5 and the reaction temperature is 180°C.
By setting the temperature above .degree. C., the PX phase is almost generated as a single phase. In this case as well, a reaction time of 1 hour or less is sufficient. This PX phase lead titanate microcrystal is a previously unknown crystal phase, and as a result of X-ray diffraction, a, = 1
It was confirmed that it was a tetragonal crystal with 2.34 people and C0 = 14.5 people. In addition, the PX phase lead titanate microcrystals are acicular particles with a thickness of 0.1 to 0°2μ and a length of 108 or more, and undergo a phase transition to a perovskite phase by heat treatment at 600 to 700°C. It was found that no change in particle shape was observed even at times, and this acicularity was maintained up to 900-1000°C. Therefore, this PX phase lead titanate microcrystal is
Since its shape is acicular and its acicular ratio is several dozen or more, it is expected to be used as a composite material.

Furthermore, in regions other than the above, amorphous lead titanate with a P b /Ti molar ratio of almost 1 is produced, but even in this case, the hydrothermal reaction cannot be carried out on the alkaline side with a pH of 7 or higher. preferable. In particular, when only lead titanate in an amorphous state is required, a pH of 1O or less is required, and the reaction temperature is preferably 110°C or higher, more preferably 150°C or higher. . The amorphous lead titanate undergoes a phase transition to the PE phase by heat treatment at 700°C or higher, but when lead titanate in the amorphous state synthesized at pH 7 or lower was heat-treated at 830°C,
PbTijO, was mainly produced. In particular, pH=4
In this case, most of the P b T ijO, and the pH
As the temperature increases, PbTij07 becomes PbTio.

It was found that the mixture was gradually mixed. From this point of view, it can be said that pH≧7 is preferable in order to utilize the amorphous lead titanate as an additive or the like.

On the other hand, in order to obtain a Ti compound or its hydrolysis product as a starting material in synthesizing the above-mentioned lead titanate microcrystals, a salt such as T i Ce, T i (So, f) L is mixed with water. or dissolve the aqueous solution in
Hydrolysis may be carried out using an alkaline aqueous solution such as KOH, NaOH, NH, +OH, and LiOH.

However, when using Ti(SOJ-), it is necessary to hydrolyze it with these alkaline solutions to create Ti0L-nH,O (titanium oxide hydrate) and repeat decantation and filtration to remove SO and Ni. good.

In addition, as a lead compound, lead acetate Pb (CH, C00)
1.3H, O, lead nitrate p b (No,),, lead chloride P
bcξ etc. can be used. However, when using lead chloride, it is preferable to treat it with alkaline hot water in advance.

Although the molar ratio of these starting materials is not particularly limited, they can be synthesized at a ratio of 1:1. Further, at this time, if Pb is in excess, it can be easily cleaned, but if Ti is in excess, a removal operation is required.

As mentioned above, an apparatus called an autoclave is used for the reaction at a high temperature of 100°C or higher, and its inner container contains high alkali,
It is preferable to use a material that can withstand high temperatures, such as polytetrafluoroethylene (so-called Teflon).

[Effect]

In this way, in the wet synthesis method of lead titanate microcrystals,
By selecting pH and synthesis temperature, PE phase (perovskite phase), PY phase (pyrochlore phase), PX phase (
It is possible to synthesize three types of lead titanate microcrystals with a new crystalline phase.In particular, by setting the pH to 12.7 or higher and the reaction temperature to 175°C or higher, it is possible to synthesize lead titanate microcrystals in the perovskite phase. are selectively synthesized.

〔Example〕 The present invention will be explained below using specific experimental examples.

It goes without saying that the present invention is not limited to these experimental examples.

Experimental Example 1 A glass of ice water was prepared, and a titanium tetrachloride solution was gently dropped little by little into it. At this time, the solution was cloudy at the beginning, but after stirring for several hours, a completely transparent titanium tetrachloride aqueous solution was obtained. This is 250m! ! The solution was transferred to a volumetric flask and used as a standard solution. Accurately take 10 ml of this standard solution, hydrolyze it with excess aqueous ammonia, and
After O,·n H,0 was filtered off, it was heat-treated at 1000°C and the concentration was determined by gravimetric method. Here, the concentration of titanium tetrachloride was 1.010 mol/L'.

On the other hand, 22.32 g of lead acetate Pb (CH,Coo), .3H,O was accurately weighed and dissolved in 100 mff of water.

Then, P b /T i = 1.0 was added to this lead acetate solution.
The above titanium tetrachloride standard solution was heated to 58°2 so that
6 ml was added gradually. At this time, a white precipitate of p b c z is formed, but this does not pose any problem in the subsequent reaction.

Furthermore, a KOH solution was prepared in advance, and this was added to adjust the pH to 14.0.

Also, is it completely melted at this time? fl-N was set to 400 m#.

Divide this into 4 equal parts to obtain sample solutions of 100 mA each, transfer each sample solution to a Teflon autoclave container, use an autoclave, and heat in an electric furnace for 100 to 23 mA.
The synthesis was carried out for a reaction time of 1 hour while changing the temperature within a range of 0°C.

The obtained precipitate was thoroughly washed with warm water, and decantation was repeated until the pH of the supernatant reached around 7. After removing impurities, this was filtered and dried day and night to obtain lead titanate microcrystals. Ta.

The obtained lead titanate microcrystals were analyzed by X-ray diffraction to determine the proportion of crystal phases contained therein. The results are shown in Figure 2. Here, the synthesized amount is expressed by the height of the diffraction X-ray peak of (101) for the PE phase and (222) for the PY phase.

From FIG. 2, it can be seen that the composite sum rapidly changes from the PY sum to the PE phase around 175°C.

Here, the lead titanate microcrystals obtained at a reaction temperature of 200°C or higher have a single PE phase, and the diffraction X-ray spectrum (by Cu target and Ni filter) is as shown in Figure 3. and A37M card (6-0452
This coincided with the peak position of No. 3, and it was confirmed that it was a single perovskite phase. Furthermore, when the lattice constants of this PE phase lead titanate microcrystal were determined using the Nelson-Riley extrapolation function, it was confirmed that it is a tetragonal crystal with a = 3.901 and c = 4.150. Ta. However, the relative intensity of each diffraction X-ray peak of the above-mentioned PE phase is significantly different from that of the A37M card. (100), (001) and (2
It was found that the diffraction X-ray peaks of (00) and (002) were very large. From this, it can be seen that the lead titanate microcrystals of the PR phase are predominantly oriented in the pressurizing direction when the glass sample plate is filled by the powder method.

Furthermore, since the PE phase lead titanate microcrystals are easily oriented just by coating, the diffraction peak (003) is not normally seen in the diffraction X-ray spectrum.
A peak of (004) also appears. Therefore, using this, we use the JOnes method to calculate β・COS θ/λ−
Plot 5in θ/λ (where β represents the integral width of the diffraction X-ray peak and λ represents the wavelength of the X-ray, respectively),
The lattice strain (in the C-axis direction) of the obtained PE phase lead titanate microcrystals was investigated.

The results are shown in Figure 5. In this Figure 5, straight line A represents PE phase lead titanate microcrystals obtained at a reaction temperature of 200°C, straight line B represents those obtained by heat treatment at 830°C, and straight line C represents those obtained by heat treatment at 1220°C. Represent each. Moreover, the broken line represents that of perovskite-type lead titanate microcrystals created by solid-phase reaction at 1055°C.

In FIG. 5, the steeper the slope of the straight line, the greater the variation in the lattice constant. Therefore, from FIG. 5, the PE phase lead titanate microcrystals obtained in this experimental example are as follows:
It is understood that especially when a certain degree of heat treatment is applied, the inclination is smaller and the lattice fluctuation with respect to the C axis is smaller than that obtained by normal solid phase reaction.

Furthermore, based on this FIG. 5, the dependence of the C-axis lattice constant variation on the heat treatment temperature in the lead titanate microcrystals of the PR phase was investigated. The results are shown in Figure 6. In this Figure 6, K indicates the range of the C-axis lattice constant of PE phase lead titanate microcrystals obtained at a reaction temperature of 200°C, and L indicates the range of the C-axis lattice constant of 83°C.
The range of the C-axis lattice constant of the heat treated product at 0°C, M is 12
Each represents the range of the C-axis lattice constant of those heat-treated at 20'C. Further, N represents that of perovskite-type lead titanate microcrystals created by solid phase reaction at 1055°C.

From FIG. 6, it can be seen that as the heat treatment temperature increases, the variation range of the C-axis lattice constant decreases. In addition, when using the solid phase method, even if heat treatment is performed at 1055°C,
300 PE phase lead titanate microcrystals obtained in this experimental example
The synthesis method of this experimental example is also advantageous in terms of this lattice variation, which is comparable to that obtained by heat treatment at about °C.

Furthermore, when we analyzed the composition of the PE phase lead titanate microcrystals synthesized in this experimental example, we found that Pb/Ti=1.006
±O, OO5, and it was confirmed that the stoichiometry was extremely high. Furthermore, from the scanning electron micrograph (SEM) shown in Fig. 7, the lead titanate microcrystals of the PE phase obtained in this experimental example were cubic (dice-shaped) with a -side of 7 to 8μ. It was observed to have an angular surface.

The PE phase lead titanate microcrystals shown in FIG. 7 are as follows:
It was prepared under the conditions of pH 14.0, reaction temperature 216° C., and reaction time 1 hour.

On the other hand, pi within the same range (but in a lower temperature range (170℃)
Figure 8 shows the diffraction of lead titanate microcrystals in the PY phase synthesized at pH = 13.1, reaction temperature 148°C, and reaction time 1 hour. The X-ray spectrum (Cu target, Ni filter) is shown. This diffraction X-ray spectrum is JCPDS
It was confirmed to be a pyrochlore phase, matching the card (26-142).It was also confirmed to be a cubic crystal with a lattice constant of 10.37 people.

Furthermore, scanning electron micrographs (SEM) show that the PY phase lead titanate microcrystals obtained in this experimental example have a particle size of about 0.
Spherical particles of 2μ were observed.

Experimental Example 2 Similarly to Experimental Example 1 above, a titanium tetrachloride standard solution with a concentration of 0.9681 mol/N was prepared.

On the other hand, 1 lead nitrate P b (N O, 7) L 3H10
After accurately weighing 9.49 g and dissolving it in 100 mff of water, 60.79 ml of the above titanium tetrachloride standard solution was added so that Pb/Ti = 1.000, and further KO
While adjusting the pH with H aqueous solution, the total solution volume was 400 mJ,
The pH was set to 12.9.

Next, this was divided into 5 equal parts, and in the same manner as in Experimental Example 1, 8Qmj! Each sample solution was reacted in an autoclave at a temperature of 130 to 230°C to obtain lead titanate microcrystals.

The obtained lead titanate microcrystals were analyzed by X-ray diffraction (Cu target, Ni filter) to determine the proportion of the crystal phase contained therein. The results are shown in Figure 9.

In addition, here, the synthesized amount is expressed by the height of the diffraction X-ray peak of (l O1) for the PE phase, (222) for the PY phase, and (330) for the PX phase. .

From this Figure 9, it can be seen that when the reaction temperature is below 130°C, the state is amorphous, but when the reaction temperature exceeds 140°C, the PY phase begins to precipitate rapidly, and as the temperature is raised further, the PX phase gradually forms. It was confirmed that the PE phase precipitated at 195° C. and suddenly precipitated at 195°C.

Experimental Example 3 A PE phase product was synthesized in the same manner as in the previous experimental example under the conditions of pH = 14.0°, reaction temperature 210°C, and reaction time 1 hour, and thermal analysis measurements were performed. The thermal analysis conditions were 20
At a heating rate of °C/win, the reference standard sample has a heat capacity of P b T i03, which is considered to be close to P by,
L a,, 7 i 0. was used. This is commercially available P
b O, L a, O, , T io, S are mixed in a predetermined molar ratio and subjected to surface phase reaction, and since the Curie point is below room temperature, there is no problem.

The results are shown in FIG. In addition, in this Figure 10,
TG indicates the result of thermal MN analysis, and DTA indicates the result of differential thermal analysis. Furthermore, in differential thermal analysis, EXO generates heat and E
ndo represents endotherm.

From FIG. 10, it can be seen that the lead titanate microcrystals in the PE phase have almost no weight loss, and two exothermic reactions are observed in the region of 400 to 500°C. Here, the exothermic reaction at high temperatures is considered to be heat generation at the Curie temperature associated with the transition from tetragonal to cubic crystals.

〔Effect of the invention〕

As is clear from the above explanation, by selecting the pH and reaction temperature in wet synthesis in an alkaline aqueous solution, perovskite type, pyrochlore type, and needle-like type with a new crystal phase can be produced. Synthesized, especially at pH 12.7 or higher.

By setting the reaction temperature to 175'C or higher, it becomes possible to selectively synthesize lead titanate microcrystals in the perovskite phase.

Furthermore, the lead titanate microcrystals obtained are extremely uniform dice-shaped particles with excellent orientation. Furthermore, this lead titanate microcrystal has high stoichiometry and high purity during synthesis, so it is less affected by impurities and has excellent properties. Furthermore, lattice distortion can be greatly reduced by particularly performing heat treatment, which is therefore considered to be extremely advantageous for piezoelectric and pyroelectric properties.

[Brief explanation of drawings]

FIG. 1 is a phase diagram according to pH and temperature in a wet synthesis method. Figure 2 is a characteristic diagram showing the temperature dependence of the PE phase and PY phase at pH 14.0, Figure 3 is a diffraction X-ray spectrum of the resulting PE phase lead titanate microcrystals, and Figure 4 is a typical This is a diffraction X-ray spectrum of perovskite-type lead titanate microcrystals obtained by the solid-phase reaction method. Figure 5 shows β・
This is a cos θ/λ−5in θ/λ correlation diagram, and FIG. 6 is a characteristic diagram showing the heat treatment temperature dependence of C-axis lattice constant variation in PE phase lead titanate microcrystals. FIG. 7 is a scanning electron micrograph of PE phase lead titanate microcrystals. FIG. 8 is a diffraction X-ray spectrum of PY phase lead titanate microcrystals synthesized at a pH of 13,1 and a reaction temperature of 148°C. Figure 9 shows the PE phase and PY phase at pH 12.9. FIG. 3 is a characteristic diagram showing the temperature dependence of the px phase. FIG. 10 is a characteristic diagram showing the results of thermal analysis of PE phase lead titanate microcrystals.

Claims (1)

[Claims] A soluble titanium compound or its hydrolysis product and a lead compound are mixed in an aqueous solution at a pH of 12.7 or higher and a temperature of 175°C.
A method for producing lead titanate microcrystals, characterized by carrying out the reaction as described above.