Dielectric composite materials including an electronically tunable dielectric phase and a calcium and oxygen-containing compound phase

• US 20040063566A1
• Filed: 09/27/2002
• Published: 04/01/2004
• Est. Priority Date: 09/27/2002
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Paratek Microwave Incorporated (Blackberry Limited)
• Inventors: Zhang, Xubai, Underhill, Elijah, Caspers, Christopher
• Granted Patent: US 6,960,546 B2
• Time in Patent Office: Days
• US Class Current: 501/134
• CPC Class Codes: B32B 2307/75 Printability
• CPC Class Codes: C04B 2235/3205 Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3213 Strontium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3215 Barium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3229 Cerium oxides or oxide-forming salts thereof
• 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 2235/3244 Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3249 containing also titanium oxide or titanates, e.g. lead zirconate titanate (PZT)
• CPC Class Codes: C04B 2235/3251 Niobium oxides, niobates, tantalum oxides, tantalates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3255 Niobates or tantalates, e.g. silver niobate
• CPC Class Codes: C04B 2235/3256 Molybdenum oxides, molybdates or oxide forming salts thereof, e.g. cadmium molybdate
• CPC Class Codes: C04B 2235/3258 Tungsten oxides, tungstates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/326 Tungstates, e.g. scheelite
• CPC Class Codes: C04B 2235/3287 Germanium oxides, germanates or oxide forming salts thereof, e.g. copper germanate
• CPC Class Codes: C04B 2235/3293 Tin oxides, stannates or oxide forming salts thereof, e.g. indium tin oxide [ITO]
• CPC Class Codes: C04B 2235/6025 Tape casting, e.g. with a doctor blade
• CPC Class Codes: C04B 2235/604 Pressing at temperatures other than sintering temperatures
• CPC Class Codes: C04B 35/4682 : based on BaTiO3 perovskite phase
• CPC Class Codes: C04B 35/47 : based on strontium titanates
• CPC Class Codes: C04B 35/6262 : of calcined, sintered clinker or ceramics
• CPC Class Codes: H01B 3/12 : ceramics
• CPC Class Codes: H01G 4/1227 : based on alkaline earth titanates

Abstract

Dielectric composite materials including an electronically tunable dielectric phase and a calcium and oxygen-containing compound are disclosed. The tunable phase may comprise a material such as barium strontium titanate. The calcium/oxygen compound may comprise CaO or a transition metal-containing compound such as Ca₂Nb₂O₇ or CaTiO₃. The material may also include a rare earth oxide dopant such as CeO₂. The materials resist dielectric breakdown and possess improved combinations of electronic properties. The materials may be tailored for specific applications.

Claims

1. An electronically tunable dielectric material comprising at least one electronically tunable dielectric phase, at least one calcium and oxygen-containing compound, and at least one rare earth oxide dopant.

2. The electronically tunable dielectric material of claim 1, wherein the calcium and oxygen-containing compound comprises from about 0.25 to about 80 weight percent of the material.

3. The electronically tunable dielectric material of claim 1, wherein the calcium and oxygen-containing compound comprises from about 1 to about 20 weight percent of the material.

4. The electronically tunable dielectric material of claim 1, wherein the calcium and oxygen-containing compound comprises CaO.

5. The electronically tunable dielectric material of claim 1, wherein the calcium and oxygen-containing compound comprises at least one metal selected from Nb, Ti, Ta, V, Cr, Zr, Mo, Hf and W.

6. The electronically tunable dielectric material of claim 5, wherein the calcium and oxygen-containing compound further comprises CaO.

7. The electronically tunable dielectric material of claim 1, wherein the calcium and oxygen-containing compound comprises Nb, Ti and/or Ta.

8. The electronically tunable dielectric material of claim 1, wherein the calcium and oxygen-containing compound comprises CaTiO₃, CaSnO₃, CaZrO₃, Ca₂Nb₂O₇, Ca₂Ta₂O₇, CaWO₄, CaMoO₄, Ca₂Ti, CaCo₃, CaHfO₃, and/or CaGeO₃.

9. The electronically tunable dielectric material of claim 1, wherein the calcium and oxygen-containing compound comprises Ca₂Nb₂O₇ and/or CaTiO₃.

10. The electronically tunable dielectric material of claim 1, wherein the rare earth oxide dopant comprises from about 0.1 to about 5 mole percent of the material.

11. The electronically tunable dielectric material of claim 1, wherein the rare earth oxide dopant comprises from about 0.25 to about 2 mole percent of the material.

12. The electronically tunable dielectric material of claim 1, wherein the rare earth oxide dopant comprises from about 0.5 to about 1.5 mole percent of the material.

13. The electronically tunable dielectric material of claim 1, wherein the rare earth oxide dopant comprises and oxide of Sc, Y, La, Ce, Pr, Nd, Sm, Dy, Gd, Ho and/or Er.

14. The electronically tunable dielectric material of claim 1, wherein the rare earth oxide dopant comprises CeO₂.

15. The electronically tunable dielectric material of claim 1, wherein the at least one electronically tunable dielectric phase is selected from barium strontium titanate, barium titanate, strontium titanate, barium calcium titanate, barium calcium zirconium titanate, lead titanate, lead zirconium titanate, lead lanthanum zirconium titanate, lead niobate, lead tantalate, potassium strontium niobate, sodium barium niobate/potassium phosphate, potassium niobate, lithium niobate, lithium tantalate, lanthanum tantalate, barium calcium zirconium titanate, sodium nitrate, and combinations thereof.

16. The electronically tunable dielectric material of claim 1, wherein the at least one electronically tunable dielectric phase comprises barium strontium titanate.

17. The electronically tunable dielectric material of claim 16, wherein the barium strontium titanate is of the formula Ba_xSr₁₋

xTiO₃, where x is from about 0.15 to about 0.6.

18. The electronically tunable dielectric material of claim 1, wherein the material has a lifetime of at least 24 hours at 85°

C. and 10 μ

A applied at 10 V/μ

A.

19. The electronically tunable dielectric material of claim 1, wherein the material has a tunability at an electric field strength of 2 V/μ

A of at least 2 percent.

20. An electronically tunable dielectric material comprising at least one electronically tunable dielectric phase and at least one calcium and oxygen-containing compound which comprises at least one metal selected from Nb, Ti, Ta, V, Cr, Zr, Mo, Hf and W.

21. The electronically tunable dielectric material of claim 20, wherein the calcium and oxygen-containing compound comprises from about 0.25 to about 80 weight percent of the material.

22. The electronically tunable dielectric material of claim 20, wherein the calcium and oxygen-containing compound comprises from about 1 to about 20 weight percent of the material.

23. The electronically tunable dielectric material of claim 20, wherein the calcium and oxygen-containing compound comprises Nb, Ti and/or Ta.

24. The electronically tunable dielectric material of claim 20, wherein the calcium and oxygen-containing compound comprises CaTiO₃, CaSnO₃, CaZrO₃, Ca₂Nb₂O₇, Ca₂Ta₂O₇, CaWO₄, CaMoO₄, Ca₂Ti, CaCo₃, CaHfO₃, and/or CaGeO₃.

25. The electronically tunable dielectric material of claim 20, wherein the calcium and oxygen-containing compound comprises Ca₂Nb₂O₇ and/or CaTiO₃.

26. The electronically tunable dielectric material of claim 20, wherein the calcium and oxygen-containing compound further comprises CaO.

27. The electronically tunable dielectric material of claim 20, wherein the material further comprises at least one rare earth oxide dopant.

28. The electronically tunable dielectric material of claim 27, wherein the rare earth oxide dopant comprises from about 0.1 to about 5 mole percent of the material.

29. The electronically tunable dielectric material of claim 27, wherein the rare earth oxide dopant comprises an oxide of Sc, Y, La, Ce, Pr, Nd, Sm, Dy, Gd, Ho and/or Er.

30. The electronically tunable dielectric material of claim 27, wherein the rare earth oxide dopant comprises CeO₂.

31. The electronically tunable dielectric material of claim 20, wherein the at least one electronically tunable dielectric phase is selected from barium strontium titanate, barium titanate, strontium titanate, barium calcium titanate, barium calcium zirconium titanate, lead titanate, lead zirconium titanate, lead lanthanum zirconium titanate, lead niobate, lead tantalate, potassium strontium niobate, sodium barium niobate/potassium phosphate, potassium niobate, lithium niobate, lithium tantalate, lanthanum tantalate, barium calcium zirconium titanate, sodium nitrate, and combinations thereof.

32. The electronically tunable dielectric material of claim 20, wherein the at least one electronically tunable dielectric phase comprises barium strontium titanate.

33. The electronically tunable dielectric material of claim 20, wherein the barium strontium titanate is of the formula Ba_xSr₁₋

xTiO₃, where x is from about 0.15 to about 0.6.

34. The electronically tunable dielectric material of claim 20, wherein the materials has a lifetime of at least 24 hours at 85°

C. and 10 μ

A and applied at 10 V/μ

A.

35. The electronically tunable dielectric material of claim 20, wherein the material has a tunability at an electric field strength of 2 V/μ

A of at least 2 percent.

36. A method of making an electronically tunable dielectric material comprising:

mixing powders of at least one electronically tunable dielectric material, at least one calcium and oxygen-containing compound, and at least one rare earth oxide dopant; and

sintering the mixture.

37. The method of claim 36, wherein the powders have average particle sizes of from about 0.1 to about 5 microns.

38. A method of making an electronically tunable dielectric material comprising:

mixing powders of at least one electronically tunable dielectric material and at least one calcium and oxygen-containing compound which comprises at least one metal selected from Nb, Ti, Ta, V, Cr, Zr, Mo, Hf and W; and

sintering the mixture.

39. The method of claim 38, wherein the powders have average particle sizes of from about 0.1 to about 5 microns.