JPH062585B2 - Method for producing lead titanate microcrystals - Google Patents

Description

The present invention relates to a method for producing perovskite-type lead titanate microcrystals useful as a ferroelectric material, a piezoelectric material, and a pyroelectric material.

[Conventional technology]

In the field of dielectric porcelain, development of a new synthesis method of dielectric oxide fine particles as a raw material has been advanced due to miniaturization of electronic parts and diversification of applications.

For example, in a multilayer ceramic capacitor, it is necessary to reduce the thickness of the ceramic layer in order to increase the capacity and reduce the size and weight, and it is an important issue to make the dielectric oxide as a raw material into fine particles. Further, from the viewpoint of the withstand voltage of the capacitor, abnormal grain growth and generation of non-uniform particles are not preferable at the sintering stage, and development of a method for synthesizing uniform fine particles is urgently needed.

Alternatively, in the case of piezoelectric actuators, bimorphs, pyroelectric infrared sensors, etc. that use piezoelectric bodies and pyroelectric bodies, development of uniform microparticulation technology is demanded for the same reason, and in particular, we considered the use for sensors. In this case, if an oriented ceramic can be produced, it is considered to be advantageous in terms of manufacturing cost and the like as compared with an oriented thin film formed by a high frequency sputtering method.

On the other hand, as the dielectric oxide that is the raw material of the dielectric porcelain,
Lead titanate, which has a number of excellent properties, is widely used. This lead titanate (PbTiO ₃ ) is generally mixed with lead oxide (PbO) and titanium oxide (TiO ₂ ), pulverized and mixed in a ball mill, and then 800-100
Pre-fire at 0 ° C, crush again until uniform,
It is synthesized by the method of performing main firing.

By the way, when synthesizing fine particles of lead titanate by such a method, evaporation of PbO becomes a big problem. That is, the higher the temperature during the calcination, the more the amount of PbO evaporated exponentially increases, which may change the composition of the obtained lead titanate fine particles. Therefore, in order to avoid this, it is necessary to take considerable measures during the heat treatment, such as firing in a PbO atmosphere. Alternatively, in order to suppress the evaporation of PbO, it is conceivable to lower the temperature of the calcination and then carry out the main calcination, but in this case, a considerable amount of unreacted PbO remains at the end of the calcination. ,
This unreacted PbO may be vaporized at the stage of the main calcination, and it is necessary to control the atmosphere here as well. Therefore, in the lead titanate fine particles obtained by the solid-phase reaction method utilizing the heat treatment as described above,
Like Pb _1-8 TiO _3, A site defects in the perovskite structure are likely to occur, and this non-stoichiometry has a high possibility of adversely affecting piezoelectric characteristics, pyroelectric characteristics and the like.
Even if it is assumed that a material having a high stoichiometry is obtained by the high temperature heat treatment, the sinterability is deteriorated as long as the above-mentioned raw material preparation procedure is performed. This is because lead titanate has the highest crystal anisotropy among those having a perovskite type structure, that is, since the square strain is large, the coefficient of thermal expansion in a specific direction is significantly different, and when the temperature is lowered from a high temperature, This is because it causes cracks. Further, in order to avoid this, various additives may be added to improve the sinterability, but in this case, a problem in piezoelectric characteristics arises. That is, lead titanate takes advantage of the fact that the electromechanical coupling coefficient of longitudinal waves is larger than that of transverse waves, and is effectively used in a portion that cannot be reached by other piezoelectric materials. It is fully conceivable that the characteristics will be deteriorated by adding. Therefore, for the above reasons, there are few examples of application of lead titanate in a pure form to dielectric porcelain by the solid-state reaction method, and one of the contradictory characteristics of piezoelectric property and sinterability is The reality is that they are put to practical use with an emphasis on them.

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

For example, Japanese Patent Publication No. 51-2080 discloses a mixed synthesis method in which a salt of an A ion and a B ion in ABO ₃ having a perovskite structure to be synthesized is reacted in an alkaline aqueous solution under boiling. However,
In this method, the condition of [A ion] / [B ion] ≧ 1.8 is required, and since the ion concentration ratio of synthesis is not 1, composition variation is likely to occur. It is a Japanese product. Therefore, to obtain crystalline particles, 30
A heat treatment of 0 to 400 ° C is required. Further, decantation is performed to remove excess PbCl ₂ that becomes an impurity during synthesis, but it is difficult to completely remove this PbCl ₂ .

Alternatively, as another method, the oxalate method and the oxalate ethanol method are known, but in the former case, the solubility of the oxalate may differ depending on the type of metal ion, or the pH range in which precipitation occurs may differ. It is difficult to obtain a uniform composition. Moreover, since an organic compound called oxalate is used, there are many problems in terms of manufacturing cost and productivity. Further, in the latter, although the uniformity of the composition is improved to some extent, problems remain in terms of manufacturing cost and productivity.

Further, a so-called metal alkoxide in which an organometallic compound represented by the general formula M (OR) _n is synthesized and a composite alkoxide represented by the general formula M _I M _II (OR) _m is synthesized and then hydrolyzed Although a law has been proposed,
There are many problems in terms of manufacturing cost and productivity. Also,
The resulting precipitate is of high purity but is amorphous,
After all, it is necessary to perform heat treatment at about 400 ° C.

[Problems to be solved by the invention]

As described above, it is difficult to synthesize the crystalline lead titanate fine particles from the liquid phase without heat treatment by the conventional synthesis method.
It was difficult to obtain lead titanate microcrystals with high uniformity and purity.

Therefore, the present invention has been proposed in view of the actual situation of the technical field as described above, and is a lead titanate microcrystal (especially perovskite-type lead titanate having high composition uniformity and purity and low lattice distortion). It is an object of the present invention to provide a method for producing lead titanate microcrystals capable of producing microcrystals.

[Means for solving problems]

The present inventors have developed a synthetic method capable of performing wet synthesis of crystalline lead titanate fine particles having high purity, uniform and less lattice distortion without heat treatment, and as a result of extensive research over a long period of time, pH and It is possible to synthesize perovskite-type lead titanate microcrystals, pyrochlore-type lead titanate microcrystals or acicular lead titanate microcrystals having a novel crystal phase by setting the synthesis temperature to a predetermined value. Found.

The present invention has been completed based on such findings, and a soluble titanium compound or a hydrolysis product thereof and a lead compound in an aqueous solution have a pH of 12.7 or higher and a temperature of 175.
It is characterized in that the reaction is carried out at a temperature of not less than 0 ° C. and under the pH and temperature conditions within the region where the perovskite type lead titanate microcrystal PE is mainly formed in FIG. 1 attached.

In the present invention, to prepare lead titanate microcrystals, for example, a soluble titanium compound such as titanium tetrachloride (TiCl ₄ ) or a hydrolysis product thereof and a hydrolysis product of a lead compound or a water-soluble salt thereof are used. Are mixed and reacted in an alkaline aqueous solution at a high temperature of 100 ° C. or higher, and the formed precipitate is washed with water or warm water to completely remove alkali cations such as K ⁺ and Na ⁺ and anions such as Cl ^−. It may be removed, filtered and dried.

Here, the pH and reaction temperature during the reaction are important, and the perovskite phase (hereinafter,
Lead titanate microcrystals of PE phase), pyrochlore phase (hereinafter, PY phase), or acicular novel crystal phase of lead titanate microcrystals (hereinafter, PX phase) are formed. The present inventors repeated experiments and attempted to create a phase diagram of lead titanate microcrystals obtained by changing the pH and reaction temperature during the above reaction. The results are shown in Fig. 1. From FIG. 1, the PY phase is stable in the low alkaline high temperature range to the high alkaline low temperature range, and the PE phase is stable only in the high alkaline high temperature range.
It has been found that the X phase only forms within a certain range. In FIG. 1, parentheses represent those that are slightly produced as by-products, and AM represents lead titanate in an amorphous state.

That is, in order to produce 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 it is preferable to set the pH to 13.1 or higher and the reaction temperature to 190 ° C or higher. By setting in such a range,
PE phase lead titanate microcrystals are selectively formed. In this case, the reaction time of 1 hour or less is sufficient. The PE phase lead titanate microcrystals obtained here are crystalline precipitates containing almost no water, and are very uniform dice-shaped crystal microparticles having a particle size of about 6 to 8 μm. Particularly, the dice-shaped crystal planes are the (h00) and (001) planes a and c, and a highly oriented sheet can be prepared by mixing a suitable resin binder and performing so-called casting. It is possible. It is also possible to produce an a-plane disk by pressure molding, and it is expected as a raw material powder suitable for highly oriented firing. Further, the particle size of the obtained lead phase titanate microcrystals of the PE phase can be changed by changing the stirring rate during the reaction, slightly shifting the pH, and the stoichiometry. high. Furthermore, the PE phase obtained here is advantageous in piezoelectric / pyroelectric properties because the strain of the lattice decreases as the temperature rises by heat treatment, and in particular, the lattice strain of the c-axis is extremely small. Is.

On the other hand, pH 12.1 or more, reaction temperature 100-190
℃, preferably pH 13.0 or more, reaction temperature 110-175
By setting the temperature to ℃, lead titanate microcrystals of PY phase are selectively formed. A reaction time of 1 hour or less is sufficient, but the longer the time, the better the crystallinity of the obtained PY phase. The PY-phase lead titanate microcrystals obtained here are also highly stoichiometric and their particle size is 0.2μ or less, which is an order of magnitude smaller than that obtained by the conventional solid-phase reaction method. Therefore, it is highly useful as a base material or an additive material for a capacitor material or a raw material for a high-density sintered body.

Further, when the pH is set to 11.2 to 13.0 and the reaction temperature is set to 145 ° C or higher, lead titanate microcrystals of the PX phase are generated, and particularly, pH 11.5 to 12.5 and the reaction temperature are set to 180 ° C or higher. By doing so, the PX phase is almost formed as a single phase. In this case, the reaction time of 1 hour or less is sufficient. This PX-phase lead titanate microcrystal is a conventionally unknown crystal phase, and as a result of X-ray diffraction, a _O = 12.34Å, c _O =
It was confirmed to be 14.5 Å tetragonal. The lead titanate microcrystals of the PX phase are acicular particles having a thickness of 0.1 to 0.2 μ and a length of 10 μ or more, and undergo a phase transition to a perovskite phase by heat treatment at 600 to 700 ° C. Even when the particle shape was not changed, the acicularity was 900 to 100.
It was found to be maintained up to 0 ° C. Therefore, this P
Since the X-phase lead titanate microcrystals are acicular and have an acicular ratio of tens or more, they are expected as a composite material.

Further, in a region other than the above, amorphous lead titanate having a Pb / Ti molar ratio of almost 1 is produced, and in this case as well, it is preferable to carry out the hydrothermal reaction on the alkaline side having a pH of 7 or more. Particularly, when only lead titanate in an amorphous state is required, a pH condition of 10 or lower is required, and a reaction temperature is preferably 110 ° C. or higher, more preferably 150 ° C. or higher. . The above-mentioned amorphous lead titanate undergoes a phase transition to a PE phase when subjected to a heat treatment at 700 ° C. or higher. However, when amorphous lead titanate synthesized at a pH of 7 or less is heat treated at 830 ° C., PbTi ₃ O ₇
Was mainly generated. Particularly, at pH = 4, this PbTi ₃ O ₇
Most of them are PbTi ₃
It was found that PbTiO ₃ was gradually mixed with O ₇ . From this, it can be said that pH ≧ 7 is preferable in order to use the amorphous lead titanate as an additive or the like.

On the other hand, in synthesizing the lead titanate microcrystals, in order to obtain a starting Ti compound or a hydrolysis product thereof, is it necessary to dissolve a salt such as TiCl ₄ or Ti (SO ₄ ) ₂ in water. , Or its aqueous solution, KOH, NaO
It may be hydrolyzed with an alkaline aqueous solution such as H, NH ₄ OH, or LiOH. However, when Ti (SO ₄ ) ₂ is used, it is hydrolyzed with these alkaline solutions to form TiO ₂
· _NH 2 creates O a (titanium oxide hydrate), by repeated decantation or filtration, may be removed ^{SO _2-4.}

Further, as the lead compound, lead acetate Pb (CH ₃ COO) is used.
₂ · _{3H 2} O, lead nitrate Pb _{(NO 3) 2,} lead chloride PbC
l ₂ etc. can be used. However, when lead chloride is used, it is preferable to treat it with alkaline hot water in advance.

The molar ratio of these starting materials is not particularly limited, but they can be synthesized at a ratio of 1: 1. At this time, if Pb is excessive, it can be easily washed, but if Ti is excessive, a removing operation is necessary.

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

[Action]

Thus, in the wet synthesis method of lead titanate microcrystals,
By selecting pH and synthesis temperature, it is possible to synthesize three types of lead titanate microcrystals of PE phase (perovskite phase), PY phase (pyrochlore phase), and PX phase (new crystal phase). Especially, pH 12.7 or higher, reaction temperature 175
By setting the temperature at or above 0 ° C, lead perovskite phase lead titanate microcrystals are selectively synthesized.

〔Example〕

 Hereinafter, the present invention will be described from specific experimental examples.

Needless to say, the present invention is not limited to these experimental examples.

Experimental example 1. Ice water was prepared in a beaker, and titanium tetrachloride solution was gently added dropwise thereto. At this time, although it became cloudy in the initial stage, when stirring was continued for several hours, a completely transparent aqueous solution of titanium tetrachloride was obtained. This was transferred to a 250 ml volumetric flask and used as a standard solution. The standard solution accurately fractionated 10ml from hydrolyzed with excess aqueous ammonia, TiO 2 _· n
After H ₂ O was filtered off, heat treatment was performed at 1000 ° C., and the concentration was determined by a gravimetric method. Here, the concentration of titanium tetrachloride is 1.0
It was 10 mol /.

Meanwhile, lead acetate _{Pb (CH 3 COO) 2 ·} 3H 2 O 22.
32 g was precisely weighed and dissolved in 100 ml of water.

Then, 58.26 ml of the above titanium tetrachloride standard solution was gradually added to this lead acetate solution so that Pb / Ti = 1.000. At this time, white precipitation of PbCl ₂ occurs,
This does not hinder the subsequent reaction.

Furthermore, a KOH solution was prepared in advance, and this was added to adjust the pH to pH = 14.0. At this time, the total amount of the solution was adjusted to 400 ml.

This is evenly divided into 4 equal parts to obtain 100 ml of each sample solution, and each sample solution is transferred to a Teflon autoclave container, and the autoclave is used for 100 to 2 by an electric furnace.
The temperature was changed within the range of 30 ° C., and the synthesis was carried out for a reaction time of 1 hour.

The obtained precipitate was thoroughly washed with warm water, and decantation was repeated until the pH of the supernatant became around 7, to remove impurities, which was then filtered off and dried for a day and night to obtain lead titanate microcrystals. .

The obtained lead titanate microcrystals were analyzed by X-ray diffraction, and the proportion of the contained crystal phase was investigated. Results are shown in FIG. The amount of each synthesis was represented by the height of the diffraction X-ray peak of (101) for the PE phase and (222) for the PY phase.

It can be seen from FIG. 2 that the synthetic phase rapidly changes from the PY phase to the PE phase at around 175 ° C.

Here, the lead titanate microcrystals obtained at a reaction temperature of 200 ° C. or higher have almost a single PE phase, and the diffraction X-ray spectrum (by Cu target and Ni filter) is as shown in FIG. And the ASTM card [6-045
It coincided with the peak position of 2], and it was confirmed that the perovskite phase was a single phase. Further, when determining the lattice constant of the lead titanate crystallites of the PE phase than extrapolation function of _{Nelson-Riley, a o = 3.901Å} , the tetragonal of c o ₌ 4.150Å was confirmed. However, the relative intensity of each diffraction X-ray peak of the PE phase is significantly different from that of the ASTM card, and is, for example, the diffraction X-ray spectrum of that obtained by the usual solid phase reaction at 1055 ° C. shown in FIG. In comparison, (100), (001) and (200), (00
It was found that the diffraction X-ray peak of 2) was very large.
From this, it is understood that the lead phase titanate microcrystals of the PE phase are predominantly oriented in the pressing direction at the time of filling the glass sample plate by the powder method.

Furthermore, since the lead titanate microcrystals in the PE phase are easily oriented by coating, they are not usually seen as diffraction peaks in the diffraction X-ray spectrum (003),
A peak of (004) also appears. Therefore, by utilizing this, using the method of Jones, β ・ cos θ / λ−sin θ / λ
(However, β represents the integrated width of the diffraction X-ray peak, and λ represents the wavelength of X-ray.) And the lattice strain (c-axis direction) of the obtained PE phase lead titanate microcrystals was investigated. It was Results are shown in FIG. In FIG. 5, a straight line A is a lead phase titanate microcrystal of PE phase obtained at a reaction temperature of 200 ° C., a straight line B is obtained by heat-treating this at 830 ° C., and a straight line C.
Represents the one heat-treated at 1220 ° C., respectively. Also,
The broken line represents that of the perovskite-type lead titanate microcrystal prepared by the solid-phase reaction at 1055 ° C.

In FIG. 5, the steeper the slope of the straight line, the greater the fluctuation of the lattice constant. Therefore, from FIG. 5, the PE-phase lead titanate microcrystals obtained in this experimental example are
It is understood that the inclination is small and the lattice variation with respect to the c-axis is small as compared with the case of a normal solid-phase reaction, especially when a certain amount of heat treatment is applied.

Further, based on FIG. 5, the heat treatment temperature dependency of the c-axis lattice constant variation in the lead phase titanate microcrystal of the PE phase was investigated. Results are shown in FIG. In FIG. 6, K represents the range of the c-axis lattice constant of PE phase lead titanate microcrystals obtained at a reaction temperature of 200 ° C., and L represents 83
C-axis lattice constant range, M was 12 after heat treatment at 0 ° C
The ranges of the c-axis lattice constants of the ones heat-treated at 20 ° C. are shown. Further, N represents that of perovskite type lead titanate microcrystals prepared by a solid phase reaction at 1055 ° C.

From FIG. 6, it can be seen that the variation range of the c-axis lattice constant decreases as the heat treatment temperature increases. Further, in the case of the solid phase method, even if heat treatment is performed at 1055 ° C.,
The PE phase lead titanate microcrystals obtained in this experimental example
It is almost the same as the one heat-treated at about ° C, and the synthetic method of this experimental example is also advantageous in terms of this lattice variation.

Further, when the composition analysis of the lead phase titanate microcrystals of the PE phase synthesized in this experimental example was performed, Pb / Ti = 1.006 ±
At 0.005, it was confirmed to be very stoichiometric. Also, from the scanning electron micrograph (SEM) shown in FIG. 7, the lead phase titanate microcrystals of the PE phase obtained in this experimental example are cubic (diced) with a side of 7 to 8 μ, and are square. It was observed that it had a rough surface. The PE phase lead titanate microcrystals shown in FIG. 7 were prepared under the conditions of pH 14.0, reaction temperature 216 ° C., and reaction time 1 hour.

On the other hand, even if the pH is within the same range, PY-phase lead titanate microcrystals are formed in a lower temperature range (170 ° C. or lower).
The figure shows the diffraction X-ray spectrum (by Cu target, Ni filter) of lead titanate microcrystals of PY phase synthesized at pH = 13.1, reaction temperature 148 ° C., reaction time 1 hour. This diffraction X-ray spectrum can be found in the JCPDS card [2
6-142] and was confirmed to be a pyrochlore phase. In addition, it was confirmed that the lattice constant was 10.27Å cubic crystal.

Further, from the scanning electron micrograph (SEM), the PY phase lead titanate microcrystals obtained in this experimental example had a grain size of about 0.2.
It was observed to be spherical particles of μ.

Experimental example 2. A titanium tetrachloride standard solution having a concentration of 0.9681 mol / was prepared in the same manner as in Experimental Example 1 above.

Meanwhile, 19.49 g of lead nitrate _{Pb (NO 3) 2 · 3H} 2 O
Was weighed accurately, dissolved in 100 ml of water, and then Pb / T
The above titanium tetrachloride standard solution 6 so that i = 1.000
0.79 ml was added, and while adjusting the pH with an aqueous KOH solution, the total amount of solution was 400 ml and pH = 12.9.

Next, this was equally divided into 5 equal parts, and by the same method as in Experimental Example 1, 80 ml of each sample solution was reacted in the range of 130 to 230 ° C. using an autoclave to obtain lead titanate microcrystals.

The obtained lead titanate microcrystals were analyzed by X-ray diffraction (Cu target, Ni filter), and the proportion of the contained crystal phase was investigated. The results are shown in Fig. 9. PE here
(101) for phase, (222) for PY phase
In the PX phase, the amount of each synthesis was represented by the height of the diffraction X-ray peak of (330).

From FIG. 9, it can be seen that while the reaction temperature is 130 ° C. or lower, it is in an amorphous state, whereas when the reaction temperature exceeds 140 ° C., the PY phase begins to precipitate rapidly, and the PX phase gradually increases with increasing temperature. It was confirmed that the PE phase suddenly began to precipitate at 195 ° C.

Experimental example 3. According to the same method as the above experimental example, pH = 14.0, reaction temperature 2
A PE phase product was synthesized under the conditions of 10 ° C. and a reaction time of 1 hour and subjected to thermal analysis measurement. The thermal analysis conditions are 20 ° C.
The heat capacity of the reference standard sample is P
Pb _1/2 La _1/3 T, which is considered to be close to bTiO _3.
iO ₃ was used. This is commercially available PbO, La ₂ O ₃ ,
TiO ₂ is mixed at a predetermined molar ratio and solid-phase reacted, and there is no problem because the Curie point is room temperature or lower.

The results are shown in Fig. 10. In addition, in FIG.
TG shows the result of thermogravimetric analysis, and DTA shows the result of differential thermal analysis. Furthermore, in differential thermal analysis, Exo is exothermic, and E
ndo represents endotherm.

From FIG. 10, the lead phase titanate microcrystals in the PE phase show almost no weight loss, and in the region of 400 to 500 ° C.,
Two exothermic reactions are observed. Here, the exothermic reaction at high temperature is considered to be exothermic at the Curie temperature accompanying the transition from tetragonal to cubic.

〔The invention's effect〕

As is clear from the above description, in wet synthesis in an alkaline aqueous solution, by selecting pH and reaction temperature, perovskite type, pyrochlore type, needle-like one having a novel crystal phase, respectively, are synthesized. But especially,
By setting the pH to 12.7 or higher and the reaction temperature to 175 ° C. or higher, it becomes possible to selectively synthesize lead perovskite phase lead titanate microcrystals.

Further, the obtained lead titanate microcrystals are very uniform dice-shaped particles and have excellent orientation. Further, since the lead titanate microcrystals have high stoichiometry during synthesis and high purity, they are less affected by impurities and have excellent characteristics. Furthermore, it is considered that the lattice distortion is extremely reduced by performing the heat treatment, which is extremely advantageous for the piezoelectric characteristics and the pyroelectric characteristics.

[Brief description of drawings]

FIG. 1 is a phase diagram according to pH-temperature in the wet synthesis method. Fig. 2 is a characteristic diagram showing the temperature dependence of PE phase and PY phase at pH 14.0, Fig. 3 is a diffraction X-ray spectrum of lead titanate microcrystals of the PE phase obtained, and Fig. 4 is usually 2 is a diffraction X-ray spectrum of perovskite-type lead titanate microcrystals obtained by the solid-state reaction method of FIG. Fig. 5 shows β ・ related to the lattice strain of PE phase lead titanate microcrystals.
FIG. 6 is a cos θ / λ-sin θ / λ correlation diagram, and FIG. 6 is a characteristic diagram showing heat treatment temperature dependence of c-axis lattice constant variation in PE phase lead titanate microcrystals. FIG. 7 is a scanning electron micrograph of lead titanate microcrystals in the PE phase. Figure 8 shows PY synthesized at pH13.1 and reaction temperature 148 ℃.
3 is a diffraction X-ray spectrum of a phase lead titanate microcrystal. FIG. 9 is a characteristic diagram showing the temperature dependence of the PE phase, PY phase, and PX phase at pH 12.9. FIG. 10 is a characteristic diagram showing the results of thermal analysis of PE phase lead titanate microcrystals.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hidemasa Tamura Inventor Hidemasa Tamura 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (56) Reference JP-A-57-106524 (JP, A) JP 57-191232 (JP, A)

Claims (1)

[Claims] 1. A soluble titanium compound or a hydrolysis product thereof and a lead compound in an aqueous solution at a pH of 12.7 or higher and a temperature of 1.
A method for producing lead titanate microcrystals, which comprises reacting at 75 ° C. or higher and under pH and temperature conditions within a region where perovskite-type lead titanate microcrystals PE are mainly formed in FIG. 1 attached.