Ceramic composition

Patent metadata

Field	Value
Publication number	US-9487445-B2
Application number	US-201414762149-A
Country	US
Kind code	B2
Filing date	Mar 24, 2014
Priority date	Mar 28, 2013
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

Abstract

A novel ceramic composition having a high relative dielectric constant. A ceramic composition includes a unit cell having at least two crystal structures selected from the group made of a monoclinic crystal, a tetragonal crystal, an orthorhombic crystal, and a rhombohedral crystal, characterized in that when the crystal structures are represented by the symmetry notation according to the Glazer method, namely x n1 y n2 z n3 , n1, n2, and n3 are at least one selected from the group made of + and −, or at least two selected from the group made of 0, +, and −. By using this ceramic composition, a novel ceramic composition having a high relative dielectric constant can be obtained.

First claim

The invention claimed is:

1. A ceramic composition which is a perovskite-type ceramic composition comprising a unit cell having at least two crystal structures selected from the group consisting of a monoclinic crystal, a tetragonal crystal, an orthorhombic crystal, and a rhombohedral crystal, wherein when the crystal structures are represented by the symmetry notation according to the Glazer method, namely x n1 y n2 z n3 , n1, n2, and n3 are at least one selected from the group consisting of + and −, or at least two selected from the group consisting of 0, +, and −,
wherein the perovskite-type ceramic composition is not derived from a solid solution consisting of BiFeO 3 and SrTiO 3 .

2. The ceramic composition according to claim 1 , wherein when the tetragonal crystal is represented by the symmetry notation according to the Glazer method, x=y and the tetragonal crystal is expressed as x 0 y 0 z − .

3. The ceramic composition according to claim 1 , wherein when the rhombohedral crystal is represented by the symmetry notation according to the Glazer method, x=y=z and the rhombohedral crystal is expressed as x − y − z − .

4. The ceramic composition according to claim 1 , wherein at least two are selected from the monoclinic crystal, the tetragonal crystal, and the rhombohedral crystal.

5. The ceramic composition according to claim 1 , wherein the ceramic composition is represented by general formula ABR 3 where A is at least one selected from the group consisting of Ba, Bi, Ca, Na, Sr, and K, B is at least one selected from the group consisting of Nb, Ta, Ti, Zr, Fe, Hf, Sn, Co, and Mn, and R is O or N.

6. The ceramic composition according to claim 2 , wherein when the rhombohedral crystal is represented by the symmetry notation according to the Glazer method, x=y=z and the rhombohedral crystal is expressed as x − y − z − .

7. The ceramic composition according to claim 2 , wherein at least two are selected from the monoclinic crystal, the tetragonal crystal, and the rhombohedral crystal.

8. The ceramic composition according to claim 3 , wherein at least two are selected from the monoclinic crystal, the tetragonal crystal, and the rhombohedral crystal.

9. The ceramic composition according to claim 6 , wherein at least two are selected from the monoclinic crystal, the tetragonal crystal, and the rhombohedral crystal.

10. The ceramic composition according to claim 2 , wherein the ceramic composition is represented by general formula ABR 3 where A is at least one selected from the group consisting of Ba, Bi, Ca, Na, Sr, and K, B is at least one selected from the group consisting of Nb, Ta, Ti, Zr, Fe, Hf, Sn, Co, and Mn, and R is O or N.

11. The ceramic composition according to claim 3 , wherein the ceramic composition is represented by general formula ABR 3 where A is at least one selected from the group consisting of Ba, Bi, Ca, Na, Sr, and K, B is at least one selected from the group consisting of Nb, Ta, Ti, Zr, Fe, Hf, Sn, Co, and Mn, and R is O or N.

12. The ceramic composition according to claim 6 , wherein the ceramic composition is represented by general formula ABR 3 where A is at least one selected from the group consisting of Ba, Bi, Ca, Na, Sr, and K, B is at least one selected from the group consisting of Nb, Ta, Ti, Zr, Fe, Hf, Sn, Co, and Mn, and R is O or N.

13. The ceramic composition according to claim 4 , wherein the ceramic composition is represented by general formula ABR 3 where A is at least one selected from the group consisting of Ba, Bi, Ca, Na, Sr, and K, B is at least one selected from the group consisting of Nb, Ta, Ti, Zr, Fe, Hf, Sn, Co, and Mn, and R is O or N.

14. The ceramic composition according to claim 7 , wherein the ceramic composition is represented by general formula ABR 3 where A is at least one selected from the group consisting of Ba, Bi, Ca, Na, Sr, and K, B is at least one selected from the group consisting of Nb, Ta, Ti, Zr, Fe, Hf, Sn, Co, and Mn, and R is O or N.

15. The ceramic composition according to claim 8 , wherein the ceramic composition is represented by general formula ABR 3 where A is at least one selected from the group consisting of Ba, Bi, Ca, Na, Sr, and K, B is at least one selected from the group consisting of Nb, Ta, Ti, Zr, Fe, Hf, Sn, Co, and Mn, and R is O or N.

16. The ceramic composition according to claim 9 , wherein the ceramic composition is represented by general formula ABR 3 where A is at least one selected from the group consisting of Ba, Bi, Ca, Na, Sr, and K, B is at least one selected from the group consisting of Nb, Ta, Ti, Zr, Fe, Hf, Sn, Co, and Mn, and R is O or N.

17. The ceramic composition according to claim 1 , wherein the perovskite-type ceramic composition is derived from a solid solution of (Bi 0.5 Na 0.5 )TiO 3 and SrTiO 3 .

18. The ceramic composition according to claim 1 , wherein the perovskite-type ceramic composition is derived from a solid solution of (Bi 0.5 Na 0.5 )TiO 3 and (Ca 0.35 Sr 0.65 )TiO 3 .

19. The ceramic composition according to claim 1 , wherein the perovskite-type ceramic composition is derived from a solid solution of (Bi 0.5 Na 0.5 )TiO 3 and CaTiO 3 .

Assignees

• Tdk Corp

Inventors

• Natsui Hidesada
• Masai Taku
• Aman Sanshiro

Classifications

• C04B2235/768

  Perovskite structure ABO3 · CPC title

• C01G49/00

  Compounds of iron · CPC title

• C04B35/47

  based on strontium titanates · CPC title

• C04B2235/3232

  Titanium oxides or titanates, e.g. rutile or anatase · CPC title

• C04B2235/5454

  nanometer sized, i.e. below 100 nm · CPC title