Dielectric ceramic and laminated ceramic capacitor

• US 8,248,753 B2
• Filed: 12/23/2009
• Issued: 08/21/2012
• Est. Priority Date: 01/16/2009
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Suzuki, Shoichiro, Takeda, Toshikazu
• Primary Examiner(s): Thomas, Eric
• Assistant Examiner(s): Ramaswamy, Arun
• Application Number:
  US12/645,985
• Publication Number:
  US 20100182733A1
• Time in Patent Office: 972 Days
• Field of Search: 3613211-3215, 361/320, 501/134, 501/136, 501/137
• US Class Current: 361/321.2
• CPC Class Codes: B32B 18/00 Layered products essentially comprising ceramics, e.g. refractory products
• CPC Class Codes: C01G 23/003 Titanates C01G23/001 takes precedence
• CPC Class Codes: C01P 2002/52 containing elements as dopants
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3215 Barium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3239 Vanadium oxides, vanadates or oxide forming salts thereof, e.g. magnesium vanadate
• CPC Class Codes: C04B 2235/3262 Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
• CPC Class Codes: C04B 2235/3293 Tin oxides, stannates or oxide forming salts thereof, e.g. indium tin oxide [ITO]
• CPC Class Codes: C04B 2235/3418 Silicon oxide, silicic acids, or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint glass constituents C04B2235/36
• CPC Class Codes: C04B 2235/6025 Tape casting, e.g. with a doctor blade
• CPC Class Codes: C04B 2235/656 characterised by specific heating conditions during heat treatment
• CPC Class Codes: C04B 2235/6582 Hydrogen containing atmosphere
• CPC Class Codes: C04B 2235/6584 at an oxygen percentage below that of air
• CPC Class Codes: C04B 2235/6588 Water vapor containing atmospheres
• CPC Class Codes: C04B 2235/768 Perovskite structure ABO3
• CPC Class Codes: C04B 2237/346 Titania or titanates
• CPC Class Codes: C04B 35/47 based on strontium titanates
• CPC Class Codes: C04B 35/6268 characterised by the applied pressure or type of atmosphere, e.g. in vacuum, hydrogen or a specific oxygen pressure
• CPC Class Codes: H01G 4/1227 based on alkaline earth titanates
• CPC Class Codes: H01G 4/30 : Stacked capacitors H01G4/33 takes precedence

Abstract

A dielectric ceramic for use in dielectric ceramic layers has a main component represented by a composition formula of (Sr_1-x-ySn_xBa_y)TiO₃, wherein x is 0.005≦x≦0.24, y is 0≦y≦0.25 in the composition formula. Preferably, the dielectric ceramic includes 0.01 mol to 5 mol of M (M is at least one of Mn and V) calculated as MO and/or 0.2 mol to 5 mol of Si calculated as SiO₂, with respect to 100 mols of the main component, and more preferably, further includes 0.1 mol to 25 mol of Ca calculated as CaO with respect to 100 mols of the main component. The dielectric ceramic has an increased dielectric constant permitting size reduction when used in a laminated ceramic capacitor.

Claims

1. A dielectric ceramic having a main component represented by a composition formula:

(Sr_1-x-ySn_xBa_y)_mTiO₃, wherein 0.005≦

x≦

0.24, 0≦

y≦

0.25 and m is about 1.

2. The dielectric ceramic according to claim 1, further comprising 0.01 mol to 5 mol of M, where M is at least one member of the group consisting of Mn and V) in terms of MO with respect to 100 mol of the main component.

3. The dielectric ceramic according to claim 2, further comprising 0.2 mol to 5 mol of Si in terms of SiO₂ with respect to 100 mol of the main component.

4. The dielectric ceramic according to claim 3, further comprising 0.1 mol to 25 mol of Ca in terms of CaO with respect to 100 mol of the main component.

5. The dielectric ceramic according to claim 4, wherein 0.01≦

x≦

0.2, y is greater than 0, and 0.99≦

m≦

1.15.

6. The dielectric ceramic according to claim 1, further comprising 0.2 mol to 5 mol of Si in terms of SiO₂ with respect to 100 mol of the main component.

7. The dielectric ceramic according to claim 6, further comprising 0.1 mol to 25 mol of Ca in terms of CaO with respect to 100 mol of the main component.

8. The dielectric ceramic according to claim 7, wherein 0.01≦

x≦

0.2, y is greater than 0, and 0.99≦

m≦

1.15.

9. The dielectric ceramic according to claim 1, further comprising 0.1 mol to 25 mol of Ca in terms of CaO with respect to 100 mol of the main component.

10. The dielectric ceramic according to claim 4, wherein 0.01≦

x≦

0.2, y is greater than 0, and 0.99≦

m≦

1.15.

11. The dielectric ceramic according to claim 1, wherein 0.01≦

x≦

0.2, y is greater than 0, and 0.99≦

m≦

1.15.

12. A laminated ceramic capacitor comprising:

a capacitor main body comprising a plurality of laminated dielectric ceramic layers, and a plurality of internal electrodes each of which is disposed at different interfaces between adjacent dielectric ceramic layers; and

a pair of external electrodes disposed at positions different from each other on the outer surface of the capacitor main body, wherein each external electrode is electrically connected to a different one of the internal electrodes, and

wherein the dielectric ceramic layers comprise the dielectric ceramic according to claim 11.

13. A laminated ceramic capacitor comprising:

a capacitor main body comprising a plurality of laminated dielectric ceramic layers, and a plurality of internal electrodes each of which is disposed at different interfaces between adjacent dielectric ceramic layers; and

a pair of external electrodes disposed at positions different from each other on the outer surface of the capacitor main body, wherein each external electrode is electrically connected to a different one of the internal electrodes, and

wherein the dielectric ceramic layers comprise the dielectric ceramic according to claim 9.

14. A laminated ceramic capacitor comprising:

a capacitor main body comprising a plurality of laminated dielectric ceramic layers, and a plurality of internal electrodes each of which is disposed at different interfaces between adjacent dielectric ceramic layers; and

a pair of external electrodes disposed at positions different from each other on the outer surface of the capacitor main body, wherein each external electrode is electrically connected to a different one of the internal electrodes, and

wherein the dielectric ceramic layers comprise the dielectric ceramic according to claim 8.

15. A laminated ceramic capacitor comprising:

a capacitor main body comprising a plurality of laminated dielectric ceramic layers, and a plurality of internal electrodes each of which is disposed at different interfaces between adjacent dielectric ceramic layers; and

a pair of external electrodes disposed at positions different from each other on the outer surface of the capacitor main body, wherein each external electrode is electrically connected to a different one of the internal electrodes, and

wherein the dielectric ceramic layers comprise the dielectric ceramic according to claim 6.

16. A laminated ceramic capacitor comprising:

a capacitor main body comprising a plurality of laminated dielectric ceramic layers, and a plurality of internal electrodes each of which is disposed at different interfaces between adjacent dielectric ceramic layers; and

a pair of external electrodes disposed at positions different from each other on the outer surface of the capacitor main body, wherein each external electrode is electrically connected to a different one of the internal electrodes, and

wherein the dielectric ceramic layers comprise the dielectric ceramic according to claim 5.

17. A laminated ceramic capacitor comprising:

a capacitor main body comprising a plurality of laminated dielectric ceramic layers, and a plurality of internal electrodes each of which is disposed at different interfaces between adjacent dielectric ceramic layers; and

a pair of external electrodes disposed at positions different from each other on the outer surface of the capacitor main body, wherein each external electrode is electrically connected to a different one of the internal electrodes, and

wherein the dielectric ceramic layers comprise the dielectric ceramic according to claim 4.

18. A laminated ceramic capacitor comprising:

a capacitor main body comprising a plurality of laminated dielectric ceramic layers, and a plurality of internal electrodes each of which is disposed at different interfaces between adjacent dielectric ceramic layers; and

a pair of external electrodes disposed at positions different from each other on the outer surface of the capacitor main body, wherein each external electrode is electrically connected to a different one of the internal electrodes, and

wherein the dielectric ceramic layers comprise the dielectric ceramic according to claim 3.

19. A laminated ceramic capacitor comprising:

a capacitor main body comprising a plurality of laminated dielectric ceramic layers, and a plurality of internal electrodes each of which is disposed at different interfaces between adjacent dielectric ceramic layers; and

a pair of external electrodes disposed at positions different from each other on the outer surface of the capacitor main body, wherein each external electrode is electrically connected to a different one of the internal electrodes, and

wherein the dielectric ceramic layers comprise the dielectric ceramic according to claim 2.

20. A laminated ceramic capacitor comprising:

a capacitor main body comprising a plurality of laminated dielectric ceramic layers, and a plurality of internal electrodes each of which is disposed at different interfaces between adjacent dielectric ceramic layers; and

a pair of external electrodes disposed at positions different from each other on the outer surface of the capacitor main body, wherein each external electrode is electrically connected to a different one of the internal electrodes, and

wherein the dielectric ceramic layers comprise the dielectric ceramic according to claim 1.