JP5801622B2 - Plate-like titanic acid compound and method for producing the same - Google Patents

Description

  The present invention relates to a plate-like titanic acid compound and a method for producing the same.

The inventors have succeeded in synthesizing plate-like BaTiO ₃ (BT) (Patent Document 1: JP 2007-22857). In this synthesis method, a plate-like compound of K _0.8 Li _0.27 □ _<0.01 Ti _1.73 O ₄ (where □ is a defect site of Ti) is obtained by solvothermal reaction of TiO ₂ with KOH and LiOH in an autoclave. The prepared plate-like compound is reacted with an acid such as dilute nitric acid to obtain plate-like titanic acid hydrate. A plate-like BaTiO ₃ can be obtained by subjecting the plate-like titanic acid hydrate to a solvothermal reaction with Ba (OH) ₂ or the like in an autoclave. In the obtained BaTiO ₃ , fine BaTiO ₃ particles aggregate to form a plate and are oriented in the direction of the (110) plane, but the primary particles of BaTiO ₃ or the crystallites themselves are not plate-shaped.

As a piezoelectric material or dielectric material, a solid solution of BaTiO ₃ and Bi _0.5 K _0.5 TiO ₃ or the like has attracted attention. The composition of this solid solution is Ba _1-x (Bi _0.5 K _0.5 ) _x TiO ₃ (0 <x <1), and the Curie temperature is as high as around 380 ° C., for example. In addition, K can be replaced with Na in any proportion, and Ba can be replaced with other alkaline earth elements such as Sr, Ca, Mg, or Pb, so the general composition is A _1-x (Bi _0.5 M _0.5 ) _x TiO ₃ Here, A represents at least one member of the group consisting of Ba, Sr, Ca, Mg, and Pb, M represents K or Na, and 0 <x <1 as described above.

Patent Document 2 (Japanese Patent Laid-Open No. 2001-151566) is a method in which BaCO ₃ , Bi ₂ O ₃ , K ₂ CO ₃ , Na ₂ CO ₃ , and TiO ₂ are wet-mixed and subjected to CIP (isotropic isostatic pressing). , A sintered body is disclosed by firing for 2 hours at 1050 to 1250 ° C., for example. The composition of the sintered body was changed to Ba _1-x (Bi _0.5 (K _z Na _1-z ) _0.5 ) _x by changing the mixing ratio of BaCO ₃ and Bi ₂ O ₃ , K ₂ CO ₃ and Na ₂ CO _3. It shows that the change can be made within the range of TiO ₃ (0 <x <1, 0 ≦ z ≦ 1). The particles constituting the sintered body of Patent Document 2 are not plate-shaped and are not oriented in a specific crystal plane direction.

In Patent Document 3 (Patent 3975518), Bi ₂ O ₃ and TiO ₂ are heated to 1050 ° C. in the presence of NaCl and KCl to synthesize plate-like Bi ₄ Ti ₃ O ₁₂ . Separately, Bi ₂ O ₃ , Na ₂ CO ₃ , K ₂ CO ₃ and TiO ₂ are heated to 850 ° C. to synthesize Bi _0.5 (Na _0.85 K _0.15 ) _0.5 TiO ₃ equiaxed powder. After mixing Bi ₄ Ti ₃ O ₁₂ and Bi _0.5 (Na _0.85 K _0.15 ) _0.5 TiO ₃ with a ball mill, adding Na ₂ CO ₃ , K ₂ CO ₃ , and TiO ₂ and forming into a tape shape, Bi _0.5 (Na _0.85 K _0.15 ) _0.5 TiO ₃ oriented in the (100) plane direction is synthesized by sintering at 1200 ° C. or the like. However, Bi _0.5 (Na _0.85 K _0.15 ) _0.5 TiO ₃ is obtained, not Ba _1-x (Bi _0.5 K _0.5 ) _x TiO ₃ , and is said to be oriented in the (100) plane direction However, it is not reported to be plate-shaped. As described above, the synthesis of plate-like Ba _1-x (Bi _0.5 K _0.5 ) _x TiO ₃ or the like is not known.

JP2007-22857 JP2001-151566 Patent 3975518

The subject of the present invention is that the composition is A _1-x (Bi _0.5 M _0.5 ) _x TiO ₃ (where A is an element of at least one member of the group consisting of Ba, Sr, Ca, Mg and Pb, and M is K or Na And 0 <x <1) to provide a plate-like titanate compound.

In the present invention, the composition formula is A _1-x (Bi _0.5 M _0.5 ) _x TiO ₃ (where A is at least one element of the group consisting of Ba, Sr, Ca, Mg, and Pb, and M is K or Na. 0 <x <1), A _1-x (Bi _0.5 M _0.5 ) _x TiO ₃ particles are aggregated into a plate shape, and the crystal is oriented in the (110) plane direction In the titanic acid compound.

The present invention also includes a compound of at least one member of the group consisting of Ti compound, Na, K, Rb, Cs and at least one element of the group consisting of Li, Mg, Co, Ni, Zn, Mn, Fe. A plate-like titanic acid represented by the general formula B _w C _y □ _z Ti _{(2- (w / 4 + ky / 4 + z)} O _{4 )} by reacting with a compound in a hydrophilic solvent under heating. The step of forming a salt (where B is at least one member of the group consisting of Na, K, Rb, Cs, and C is at least one member of the group consisting of Li, Mg, Co, Ni, Zn, Mn, Fe) , K represents the valence of the C element, □ represents the defect site of Ti, 0 <w <1, 0 <y <w, 0 ≦ z, 0 <y + z <1),
Reacting the obtained plate-like titanate with an acid to form plate-like titanate hydrate,
The obtained plate-like titanic acid hydrate is reacted with a compound of element A and a hydrophilic solvent under heating, using at least one member of the group consisting of Ba, Sr, Ca, Mg, and Pb as element A. In the method for producing a plate-like titanate compound, the step of introducing an A element into the plate-like titanate hydrate,
In the step of introducing the A element, by reacting the compound of the A element with the plate-like titanate hydrate at a ratio of less than 1 mol with respect to 1 mol of the Ti element in the plate-like titanate hydrate, While obtaining a plate-like substance composed of titanic acid hydrate and ATiO ₃ ,
By reacting the obtained plate-like substance with a compound of at least one member of the group consisting of Na and K, and a Bi compound in a hydrophilic solvent under heating, the composition formula is A _1-x (Bi _0.5 M _0.5 ) _x TiO ₃ (where M is K or Na, 0 <x <1) is agglomerated into a plate shape, and the crystal is oriented in the (110) plane direction Obtaining a titanic acid compound.

In the step of obtaining the plate-like titanate compound, for example, a plate-like substance containing ATiO ₃ , an oxide of bismuth and titanium, and titanic acid hydrate or titanium oxide is formed in the early stage of the reaction, and M in the late stage of the reaction. The element is introduced into the plate-like substance generated to form the A _1-x (Bi _0.5 M _0.5 ) _x TiO ₃ particles. A is preferably at least a member of the group consisting of Ba, Sr, Ca, and Mg, more preferably Ba or Sr, and particularly preferably Ba. In this specification, the description relating to the plate-like titanate compound also applies to the production method thereof, and the description relating to the production method of the plate-like titanate compound also applies to the plate-like titanate compound as it is. Na and K have the same behavior in the synthesis of the plate-like titanate compound, and Na can be used in place of K, or a part of K can be substituted with Na. In this specification, the hydrophilic solvent refers to a solvent that is freely miscible with water, such as water itself, ethanol, methanol, isopropanol, glycerin and the like. In this specification, the term “plate-like” does not mean that the shape of the secondary particles is plate-like, and that the primary particles or crystallites themselves are plate-like.

  Until the synthesis of plate-like titanic acid hydrate, it is known from Patent Document 1. Z representing the number of defect sites □ in Ti is generally a small number, for example, 0 or more and 0.01 or less. The element B is particularly preferably K which is inexpensive and has an appropriate ionic radius, and the element C is preferably Li which can be easily removed by an acid and has a small amount of impurities. w is, for example, 0.5 or more and less than 1.0, y is, for example, 0.2 or more and less than 0.5, and w> y, and particularly preferably, w is 0.6 or more and less than 1.0, and y is 0.2 or more and less than 0.4. Conversion to titanic acid hydrate with an acid is carried out, for example, at room temperature to 100 ° C., particularly preferably at room temperature to 60 ° C.

For example, when Ba (OH) ₂ etc., BiCl ₃ and KOH are mixed in plate-like titanic acid hydrate and solvothermal reaction is carried out in an autoclave, Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ (BBKT) etc. Can be synthesized. However, the obtained Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ etc. is not plate-like, but in the process where the plate-like titanic acid hydrate changes to Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ etc. The shape of is lost. On the other hand, when Ba or the like is introduced into the plate-like titanic acid hydrate by a solvothermal reaction at a ratio of less than 1 mol with respect to 1 mol of Ti, BaTiO ₃ etc. and titanic acid water remain while maintaining the plate-like shape. A substance consisting of a Japanese product can be obtained.

When Bi and K or Na are introduced into the obtained plate-like material by a solvothermal reaction, a portion of the titanic acid hydrate remains Bi ₁₂ TiO ₂₀ , Bi ₄ while maintaining the plate-like shape at the initial stage of the reaction. It changes to bismuth titanate compounds such as Ti ₃ O ₁₂ . If the reaction is continued, K is introduced into the plate-like material composed of an aggregate of BaTiO ₃ , titanic acid hydrate or titanium oxide, and bismuth titanate compound, and the composition is uniform within the plate-like material. Thus, plate-like Ba _1-x (Bi _0.5 M _0.5 ) _x TiO ₃ (M is Na or K) is obtained. The obtained Ba _1-x (Bi _0.5 M _0.5 ) _x TiO ₃ is oriented in the (110) plane direction and is suitable for a dielectric or piezoelectric material. The orientation in the direction of the (110) plane is the same for other plate-like titanate compounds of the present invention.

When Ba (OH) ₂ is replaced with other alkaline earth hydroxides or salts, Pb (OH) ₂ or Pb (NO ₃ ) ₂ etc., Ba is substituted with other alkaline earth or Pb Is obtained. Further, BaTiO _{3 and the} like are more stable than titanic acid hydrate, and even when the generated BaTiO _{3 and the} like come into contact with ions such as Bi, K, and Na, elements such as Ba are not replaced by Bi or the like. Therefore, when an element such as Ba is first introduced according to the target composition, and then Bi and K or Na are introduced, the target plate-like titanate compound is obtained.

a: Precursor titanate hydrate H _1.07 Ti _1.73 O ₄ xH ₂ O (HTO), b: HTO, Ba (OH) ₂ and BiCl ₃ in 150 mol / L KOH aqueous solution at 150 ° C and _{Ba 0.5 (Bi 0.5 K 0.5)} 0.5 TiO 3 was reacted for 12 hours, c: X-ray of the other by changing the reaction temperature to 200 ° C. the Ba _0.5 was reacted under the same conditions _{(Bi 0.5 K 0.5) 0.5 TiO} 3 Diffraction pattern a: FE-SEM image (Field Emission Scanning Electron Microscope Image) of HTO in Fig. 1a and b: Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO _{3 in} Fig. 1c a: Precursor titanate hydrate HTO, b: 0.5BaTiO ₃ -0.5HTO complex with partially introduced Ba into HTO, and c: 0.5BaTiO ₃ -0.5HTO complex with 3mol / L KOH Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ reacted with BiCl ₃ at 150 ° C. for 12 hours in aqueous solution, d: Ba _0.5 (reacted under the same conditions as c except that the reaction temperature was changed to 200 ° C. X-ray diffraction pattern of Bi _0.5 K _0.5 ) _0.5 TiO ₃ a: TEM image (Transmission Electron Microscope Image) of plate-like HTO, b: SAED pattern (Selected Area Electron Diffraction Pattern) of plate-like HTO, and c: TEM image and d of 0.5BaTiO ₃ -0.5HTO composite : Diagram showing SAED pattern of 0.5BaTiO ₃ -0.5HTO composite X-ray diffractogram of a product obtained by reacting 0.5BaTiO ₃ -0.5HTO complex and BiCl _{3 in} water at 200 ° C for 12 hours with varying KOH concentration. A is 0.1 mol / L KOH concentration, b is 0.5 mol / L, c is 1.5 mol / L, d is 3 mol / L, e is 5 mol / L, and f is 8 mol / L. In the FE-SEM image of the sample in Fig. 5, a is an image of a 0.5BaTiO ₃ -0.5HTO complex, b is an image of a product synthesized with a KOH concentration of 0.1 mol / L, and c is a product generated at 0.5 mol / L. Product image, d is the product image at 1.5 mol / L, e is the product image at 3 mol / L, and f is the product image at 8 mol / L. X-ray diffraction pattern of the product obtained by reacting 0.5BaTiO ₃ -0.5HTO complex with BiCl ₃ in 3mol / L KOH aqueous solution at 200 ° C for a predetermined time, a is the reaction time is 2 hours, b is 4 hours, c was 6 hours, d was 12 hours, and e was 48 hours. In the FE-SEM image of each sample in FIG. 7, a is a reaction time of 2 hours, b is 4 hours, c is 6 hours, and d is 48 hours. In the TEM images and EDS (Energy Dispersive X-ray Spectrum) of samples b and d in FIG. 7, the reaction time is 4 hours for c and d, and the reaction time is 12 hours for e and f. 7 shows the SAED pattern (a, c) and HRTEM image (b, d) (High Resolution Transmission Electron Microscope Image) of samples b and d in FIG. Is 12 hours. Diagram showing the model of plate-like bismuth potassium barium titanate (Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ )

  Although the optimal example for implementing this invention is shown below, this invention is not restrict | limited to an Example, Example can be changed according to well-known techniques, such as patent document 1, and those well-known to those skilled in the art.

Add titanium oxide, potassium hydroxide, and lithium hydroxide to an autoclave with a capacity of 30 mL so that the atomic ratio of Ti: K: Li is 5: 4: 1 and stir at 250 ° C. for 20 hours (more generally The reaction was carried out under hydrothermal conditions at 200 to 300 ° C. for 10 to 40 hours to obtain plate-like particles of K _0.80 Li _0.27 □ _<0.01 Ti _1.73 O ₄ . Note that □ indicating a defective portion of Ti is generally a small positive number less than 0.01. The composition of the plate-like particles was determined by atomic absorption analysis, and confirmed to be potassium lithium titanate by X-ray diffraction. The plate-like particles were treated with a 1M-HNO ₃ aqueous solution (20 mol of HNO ₃ per mol of plate-like particles) at room temperature to obtain plate-like H _1.07 Ti _1.73 O ₄ × H ₂ O (hereinafter referred to as HTO).

The obtained HTO was reacted with Ba (OH) ₂ and BiCl ₃ in a 3 mol / L KOH aqueous solution at 150 ° C. and 200 ° C. for 12 hours, respectively. Ba and Ti were mixed at a molar ratio of 0.5: 1, and Bi and Ti were similarly mixed at a molar ratio of 0.25: 1. The X-ray diffraction pattern of the raw material HTO (plate-like titanate hydrate) and the product Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ is shown in FIG. HTO is changed to Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ regardless of whether the reaction temperature is 150 ° C. or 200 ° C. FIG. 2 shows an FE-SEM image of the product reacted at 200 ° C. with the raw material HTO. The raw material HTO is a plate-like compound, but the product is no longer plate-like.

When Ba and Bi were introduced into HTO in one step, a plate-like compound could not be obtained. Therefore, we first introduced Ba into HTO and then introduced Bi and K. As a final goal, Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ was synthesized. First, Ba (OH) ₂ was added at a ratio of 0.5 mole to 1 mole of HTO and reacted by a solvothermal reaction. In order to gently introduce Ba into HTO, a 28: 2 ethanol-water mixed solvent in a volume ratio was used as a solvent, but the type of the solvent is arbitrary. At 150 ° C. and 200 ° C., Ba in Ba (OH) ₂ was introduced stoichiometrically into HTO. The obtained 0.5BaTiO ₃ -0.5HTO complex, in KOH aqueous solution 3 mol / L, and allowed to react each 12 hours at a reaction temperature of BiCl ₃ and 0.99 ° C. or 200 ° C.. If the product is Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ , the 3 mol / L KOH aqueous solution contains 50 times the amount of K atoms stoichiometrically required. In each example, a stoichiometrically required amount of Bi compound was used, but it is preferable to use a Bi compound that is not less than the stoichiometrically required amount and not more than 1.05 times. Fig. 3a shows the X-ray diffraction pattern of the plate-like HTO, b shows the X-ray diffraction pattern of the 0.5BaTiO ₃ -0.5HTO composite, c shows the X-ray diffraction pattern of the product at 150 ° C, and 200 ° C. The X-ray diffraction pattern of the product is shown in d. Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ (BBKT) is produced at 150 ° C. and 200 ° C., and TiO ₂ and Bi ₁₂ TiO ₂₀ are detected at 150 ° C. From this, it can be seen that the temperature of the solvothermal reaction is preferably 150 ° C or higher, the upper limit is, for example, 250 ° C, the reaction temperature is preferably 160 ° C or higher and 250 ° C or lower, particularly preferably 180 ° C or higher and 250 ° C or lower. is there.

FIG. 4 shows a TEM image and a SAED pattern of a plate-like HTO and a 0.5BaTiO ₃ -0.5HTO composite. FIG. 4c is a TEM image of the 0.5BaTiO ₃ -0.5HTO composite. Compared with the HTO TEM image a, it can be seen that BaTiO ₃ nanoparticles are distributed in the plate-like secondary particles. Moreover, it can be seen from the SAED pattern of the plate-like HTO that the sample is a single phase of HTO. In contrast, in the SAED pattern of the 0.5BaTiO ₃ -0.5HTO composite, it can be seen that the HTO pattern and the BaTiO ₃ pattern coexist.

FIG. 5 shows X-ray diffraction patterns of products obtained by reacting 0.5BaTiO ₃ -0.5HTO complex with BiCl ₃ at 250 ° C. for 12 hours in various concentrations of aqueous KOH. The KOH concentration is 0.1 mol / L for a, 0.5 mol / L for b, 1.5 mol / L for c, 3 mol / L for d, 5 mol / L for e, 8 mol / L for f, Bi ₄ Ti ₃ O for a ₁₂ , Bi ₄ Ti ₃ O ₁₂ and Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ coexist in b, and only Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ is seen in c to f.

FIG. 6 shows the FE-SEM image for the product of FIG. 5, where a is the raw material 0.5BaTiO ₃ -0.5HTO composite, b is 0.1 mol / L, c is 0.5 mol / L, and d is 1.5 mol. / L, e is 3 mol / L, and f is 8 mol / L. In b to f, a plate-like structure is maintained. In FIG. 5, Bi ₄ Ti ₃ O ₁₂ remained when the KOH concentration was 0.5 mol / L. Therefore, the KOH concentration is preferably 1 mol / L or more and 8 mol / L or less.

FIG. 7 shows an X-ray diffraction pattern of a product obtained by hydrothermal reaction of 0.5BaTiO ₃ -0.5HTO complex in BiCl ₃ and 3 mol / L KOH aqueous solution at 200 ° C. with varying reaction time. The reaction time is 2 hours for a, 4 hours for b, 6 hours for c, 12 hours for d, and 48 hours for e. The peak of Bi ₁₂ TiO ₂₀ is observed at 2 hours and 4 hours, and Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ is almost completely generated after 6 hours or more.

  FIG. 8 is an FE-SEM image of the sample of FIG. 7, where the reaction time is 2 hours for a, 4 hours for b, 6 hours for c, and 48 hours for d. When the reaction time is 48 hours as in d, the plate-like shape collapses. In view of the fact that the plate-like shape can be maintained by the reaction time of 12 hours in FIG. 6, the reaction time is preferably 5 hours or more and 20 hours or less.

  FIG. 9 shows a TEM image and an EDS spectrum of the sample of FIG. 7, where c and d have a reaction time of 4 hours, and e and f have a reaction time of 12 hours. When EDS analysis is performed on each of the c and e samples at three locations A, B, and C, the results are as shown in d and f in FIG. In a sample with a reaction time of 12 hours, the composition is uniform regardless of the location.

FIG. 10 shows the SAED pattern and HRTEM image of samples b and d in FIG. 7. The reaction time is 4 hours for the SAED pattern and b HRTEM image of a, and the reaction time is 12 hours for the c SAED pattern and d HRTEM image. It is. When the reaction time is 4 hours, the diffraction pattern and crystal lattice of Bi ₁₂ TiO ₂₀ are observed, and when the reaction time is 12 hours, only the diffraction pattern and crystal lattice of Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ are observed. It was.

From the above, the temperature of the solvothermal reaction is preferably 150 ° C. or higher and 250 ° C. or lower, more preferably 160 ° C. or higher and 250 ° C. or lower, and particularly preferably 180 ° C. or higher and 250 ° C. or lower. It can be seen that the reaction time is preferably 5 or more and 20 hours or less, and the KOH concentration is preferably 1 mol / L or more and 8 mol / L or less. When the reaction time is long, the reaction temperature is high, or the KOH concentration is high, the plate-like shape tends to collapse. Conversely, when the reaction temperature is low, the reaction time is short, or the KOH concentration is low, intermediate products other than Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ tend to remain. The above conditions are the most preferable conditions. For example, if the reaction time is 48 hours even at 130 ° C. and the KOH concentration is 8 mol / L, Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ can be obtained. Even when the reaction time is 2 hours, Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ can be obtained in the same manner if the KOH concentration is 8 mol / L and the reaction temperature is 250 ° C. Furthermore, the reaction conditions may be the same when K is introduced and when Na is introduced.

A production model of Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ is shown in FIG. For example, when a plate-like HTO is reacted with Ba (OH) ₂ with 0.5 / 1 Ba-Ti, the topological 0.5HTO-0.5BaTiO ₃ (BT-HTO) A nanocomposite is obtained. In this product, BaTiO ₃ particles are distributed inside the plate-like secondary particles as shown in FIG. 4c. The product was further Bi ³⁺ and K ⁺ and OH ^- and by hydrothermal reaction, initially Bi is introduced into the HTO, plate-like material containing a bismuth titanate compounds such as BaTiO ₃ and Bi ₁₂ TiO ₂₀ From the point of chemical stoichiometry, it can be seen that HTO or TiO ₂ is also included. When the reaction is further continued, K ⁺ is introduced into the particles and the composition becomes uniform. At this time, plate-like Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ is generated by heteroepitaxial crystal growth. All of the produced Ba _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ was strongly oriented in the (110) plane direction.

Although K element was used in the examples, Ba _0.5 (Bi _0.5 Na _0.5 ) _0.5 TiO ₃ could be synthesized in the same manner even when Na element was used. Of course, the ratio of K and Na can be any value. Instead of reacting HTO with Ba (OH) ₂ , reacting Sr (OH) ₂ , Ca (OH) ₂ , Mg (OH) ₂ , Pb (OH) ₂ with Sr _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ , Ca _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ , Mg _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ , Pb _0.5 (Bi _0.5 K _0.5 ) _0.5 TiO ₃ etc. can be synthesized It was. It was used BiCl ₃ as Bi source in the embodiment, may be a soluble Bi compound in an alkaline water at 200 ° C. temperature of about such BiI _3. A part of KOH may be KCl or K ₂ O. Instead of Ba (OH) ₂ , Ba ²⁺ ions may be introduced by BaCl ₂ or the like. In the examples, an example of x = 0.5 was studied as Ba _X (Bi _0.5 K _0.5 ) _1-x TiO ₃ . For each example of x = 0.05, 0.1, 0.3, 0.7, 0.9, 0.94, the same synthesis as in the example was attempted with a KOH concentration of 3 mol / L, a reaction temperature of 200 ° C., and a reaction time of 6 hours. Successful. Therefore, 0 <x <1, preferably 0.1 ≦ x ≦ 0.95, and particularly preferably 0.1 ≦ x ≦ 0.94.

Claims (7)

The composition formula is A _1-x (Bi _0.5 M _0.5 ) _x TiO ₃ (where A is an element of at least one member of the group consisting of Ba, Sr, Ca, Mg, and Pb, M is K or Na, and 0 < A plate-like titanate compound in which x <1), A _1-x (Bi _0.5 M _0.5 ) _x TiO ₃ particles are aggregated into a plate shape, and crystals are oriented in the (110) plane direction .   The plate-like titanic acid compound according to claim 1, wherein A is an element of at least one member of the group consisting of Ba, Sr, Ca, and Mg.   The plate-like titanate compound according to claim 2, wherein A is Ba. Hydrophilic compounds of Ti compounds, compounds of at least one member of the group consisting of Na, K, Rb, Cs and compounds of at least one member of the group consisting of Li, Mg, Co, Ni, Zn, Mn, Fe A plate titanate represented by the general formula B _w C _y □ _z Ti _{(2- (w / 4 + ky / 4 + z)} O ₄ ( Where B is at least one element of the group consisting of Na, K, Rb, Cs, C is at least one element of the group consisting of Li, Mg, Co, Ni, Zn, Mn, Fe, and k is the C element □ represents a defect site of Ti, 0 <w <1, 0 <y <w, 0 ≦ z, 0 <y + z <1),
Reacting the obtained plate-like titanate with an acid to form plate-like titanate hydrate,
The obtained plate-like titanic acid hydrate is reacted with a compound of element A and a hydrophilic solvent under heating, using at least one member of the group consisting of Ba, Sr, Ca, Mg, and Pb as element A. In the method for producing a plate-like titanate compound, the step of introducing an A element into the plate-like titanate hydrate is performed.
In the step of introducing the A element, by reacting the compound of the A element with the plate-like titanate hydrate at a ratio of less than 1 mol with respect to 1 mol of the Ti element in the plate-like titanate hydrate, While obtaining a plate-like substance composed of titanic acid hydrate and ATiO ₃ ,
By reacting the obtained plate-like substance with a compound of at least one member of the group consisting of Na and K, and a Bi compound in a hydrophilic solvent under heating, the composition formula is A _1-x (Bi _0.5 M _0.5 ) _x TiO ₃ (where M is K or Na, 0 <x <1) is agglomerated into a plate shape, and the crystal is oriented in the (110) plane direction Obtaining a plate-like titanate compound, and a method for producing a plate-like titanate compound. In the step of obtaining the plate-like titanate compound, a plate-like substance containing ATiO ₃ , an oxide of bismuth and titanium, and titanate hydrate or titanium oxide is formed in the early stage of the reaction, and M in the late stage of the reaction. The method for producing a plate-like titanic acid compound according to claim 4, wherein the element is introduced into the plate-like substance formed to form the A _1-x (Bi _0.5 M _0.5 ) _x TiO ₃ particles.   The method for producing a plate-like titanate compound according to claim 4 or 5, wherein A is an element of at least one member of the group consisting of Ba, Sr, Ca, and Mg.   The method for producing a plate-like titanate compound according to claim 6, wherein A is Ba.