Titanium-Containing Perovskite Compound and Production Method Thereof

• US 20070205389A1
• Filed: 03/24/2005
• Published: 09/06/2007
• Est. Priority Date: 03/25/2004
• Status: Abandoned Application

• Current Assignee: Showa Denko KK
• Original Assignee: Showa Denko KK
• Inventors: Kurozumi, Tadatoshi, Tanaka, Jun, Shirakawa, Akihiko
• Application Number:
  US10/593,832
• Publication Number:
  US 20070205389A1
• Time in Patent Office: Days
• US Class Current: 252/62.90R
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 23/003 Titanates C01G23/001 takes precedence
• CPC Class Codes: C01G 23/006 Alkaline earth titanates
• CPC Class Codes: C01G 23/047 Titanium dioxide
• CPC Class Codes: C01G 23/07 Producing by vapour phase processes, e.g. halide oxidation
• CPC Class Codes: C01P 2002/34 perovskite-type (ABO3)
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: C01P 2006/42 Magnetic properties
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3232 Titanium oxides or titanates, e.g. rutile or anatase
• CPC Class Codes: C04B 2235/3236 Alkaline earth titanates
• CPC Class Codes: C04B 2235/5409 expressed by specific surface values
• CPC Class Codes: C04B 2235/5445 submicron sized, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 2235/5454 nanometer sized, i.e. below 100 nm
• CPC Class Codes: C04B 2235/5463 Particle size distributions
• CPC Class Codes: C04B 2235/549 the particle size being expressed by crystallite size or primary particle size
• CPC Class Codes: C04B 2235/761 Unit-cell parameters, e.g. lattice constants
• CPC Class Codes: C04B 2235/9615 : Linear firing shrinkage
• CPC Class Codes: C04B 35/46 : based on titanium oxides or titanates containing also zirconium or hafnium oxides, zirconates or hafnates C04B35/49
• CPC Class Codes: C04B 35/4682 : based on BaTiO3 perovskite phase
• CPC Class Codes: H01G 4/1227 : based on alkaline earth titanates
• CPC Class Codes: H10N 30/853 : Ceramic compositions

Abstract

The present invention relates to a method for producing a titanium-containing perovskite compound, characterized in that the method comprises a step of reacting titanium oxide produced through a vapor-phase method with at least one element selected from a group of alkaline earth metal compound and Pb compound in an alkaline solution; a perovskite compound obtained by the method; and electronic materials and the like using the compound. The titanium-containing perovskite compound obtained by the method in the present invention has a small particle diameter and few impurities, is excellent in electric characteristics, and enables to make the size of electronic devices smaller since the compound can be shaped in a thin film product.

Claims

1. A method for producing a titanium-containing perovskite compound, characterized in that the method comprises a step of reacting titanium oxide produced through a vapor-phase method with at least one element selected from a group of alkaline earth metal compound and Pb compound in an alkaline solution.

2. The method for producing a titanium-containing perovskite compound as claimed in claim 1, wherein primary particles of the titanium-containing perovskite compound have a diameter (D1) that is 50 to 200% the size of primary particles of the titanium oxide serving as a starting material, the size (D1) being determined by converting the specific surface area (S) of the particles obtained by the BET method to the total surface area of spheres in accordance with the following equation (1):

D1=6/ρ

S 

 

(1)

wherein ρ

represents a density of the particles and S represents a BET specific surface area.

3. The method for producing a titanium-containing perovskite compound as claimed in claim 1, using ultrafine particles of titanium oxide having a BET specific surface area of 3 to 200 m²/g.

4. The method for producing a titanium-containing perovskite compound as claimed in claim 1, using the titanium oxide produced by oxidizing titanium tetrachloride at high temperature by use of an oxidizing gas.

5. The method for producing a titanium-containing perovskite compound as claimed in claim 4, using the titanium oxide produced by a vapor-phase method is produced by respectively introducing a titanium tetrachloride-containing gas and an oxidizing gas which are heated in advance to 500°

C. or higher into a reaction tube at a flow rate of 10 m/sec or more.

6. The method for producing a titanium-containing perovskite compound as claimed in claim 5, using the titanium oxide produced by retaining the titanium tetrachloride-containing gas and the oxidizing gas in the reaction tube for reaction for one second or shorter under a high-temperature condition higher than 600°

C.

7. The method for producing a titanium-containing perovskite compound as claimed in claim 6, using the titanium oxide produced under a condition of an average gas flow rate in the reaction tube of 5 m/sec or more.

8. The method for producing a titanium-containing perovskite compound as claimed in claim 1, using the titanium oxide produced by a vapor-phase method is produced by introducing the preheated titanium tetrachloride-containing gas and oxidizing gas into the reaction tube in such a manner that turbulence is generated in the reaction tube.

9. The method for producing a titanium-containing perovskite compound as claimed in claim 8, using the titanium oxide produced by introducing the titanium tetrachloride-containing gas and the oxidizing gas into the reaction tube through a coaxial parallel flow nozzle and the inner tube of the coaxial parallel flow nozzle has an inside diameter of 50 mm or less.

10. The method for producing a titanium-containing perovskite compound as claimed in claim 4, wherein the titanium-tetrachloride-containing gas has a titanium tetrachloride content of 10 to 100%.

11. The method for producing a titanium-containing perovskite compound as claimed in claim 5, wherein each of the titanium tetrachloride-containing gas and the oxidizing gas is heated in advance at 800°

C. or higher.

12. The method for producing a titanium-containing perovskite compound as claimed in claim 1, wherein the titanium oxide produced by a vapor-phase method has a mean particle diameter at a 90% cumulative weight on the particle size distribution curve (D₉₀) of 2.2 μ

m or less.

13. The method for producing a titanium-containing perovskite compound as claimed in claim 1, wherein the titanium oxide produced through a vapor-phase method has a distribution constant n, as calculated from the following Rosin-Rammler equation (2), of 1.7 or more:

R=100 exp(−

bDⁿ) 

 

(2)

wherein D is a particle diameter;

R is the percentage of the number of particles larger than D (particle diameter) with respect to the total number of particles;

n is a distribution constant; and

b is a reciprocal of particle characteristic constant.

14. The method for producing a titanium-containing perovskite compound as claimed in claim 1, wherein the titanium oxide produced by a vapor-phase method contains anatase-crystal-form titanium oxide.

15. The method for producing a titanium-containing perovskite compound as claimed in claim 1, using an alkaline solution in which a basic compound exists.

16. The method for producing a titanium-containing perovskite compound as claimed in claim 15, wherein the basic compound is selected from ammonium, organic amine and hydroxide of ammonium salt.

17. A titanium-containing perovskite compound, which is produced by a method as claimed in claim 1.

18. The titanium-containing perovskite compound exhibiting ferroelectricity as claimed in claim 17.

19. A dielectric material containing a titanium-containing perovskite compound as claimed in claim 18.

20. A paste containing a titanium-containing perovskite compound as claimed in claim 18.

21. A slurry containing a titanium-containing perovskite compound as claimed in claim 18.

22. A thin-film product containing a titanium-containing perovskite compound as claimed in claim 18.

23. A dielectric ceramics containing a titanium-containing perovskite compound as claimed in claim 18.

24. A pyroelectric ceramics containing a titanium-containing perovskite compound as claimed in claim 18.

25. A piezoelectric ceramics containing a titanium-containing perovskite compound as claimed in claim 18.

26. A capacitor containing a dielectric ceramics as claimed in claim 23.

27. An electronic device containing a thin film product as claimed in claim 22.

28. A sensor containing a thin film product as claimed in claim 22.

29. A dielectric film employing a titanium-containing perovskite compound as claimed in claim 18.

30. A capacitor employing a dielectric film as claimed in claim 29.

31. A ferroelectric memory employing a titanium-containing perovskite compound as claimed in claim 18.

32. A capacitor built in a substrate, which capacitor employs a titanium-containing perovskite compound as claimed in claim 18.