Dielectric material, a method for producing the same and a dielectric resonator device comprising same

• US 6,117,806 A
• Filed: 10/24/1997
• Issued: 09/12/2000
• Est. Priority Date: 10/25/1996
• Status: Expired due to Term

• Current Assignee: NGK Spark PLUG Company Limited (Niterra Co., Ltd.)
• Original Assignee: NGK Spark PLUG Company Limited (Niterra Co., Ltd.)
• Inventors: Ohbayashi, Kazushige, Tosa, Akifumi, Yokoi, Hitoshi
• Primary Examiner(s): GROUP, KARL E
• Application Number:
  US08/957,627
• Time in Patent Office: 1,054 Days
• Field of Search: 501/135, 501/137, 501/138, 501/139
• US Class Current: 501/135
• CPC Class Codes: C04B 35/495 based on vanadium, niobium, tantalum, molybdenum or tungsten oxides or solid solutions thereof with other oxides, e.g. vanadates, niobates, tantalates, molybdates or tungstates
• CPC Class Codes: H01P 7/10 Dielectric resonators

Abstract

Dielectric materials are disclosed that are based on BaO--ZnO--Ta₂ O₅ represented by the formula Ba(Zn_1/3 Ta_2/3)O₃. Ba has been partly replaced by K and either Zn or Ta has been replaced by at least one element selected from Mg, Zr, Ga, Ni, Nb, Sn. The dielectric materials have a relatively high permittivity, a small absolute value of the temperature coefficient of resonance frequency, and a high unloaded quality factor. A method for producing the dielectric materials is also disclosed which includes mixing given amounts of starting materials, such as, for example, BaCO₃, ZnO, Ta₂ O₅, K₂ CO₃, MgCO₃, SnO₂ or ZrO₂, compacting the mixture to produce a compact, sintering the compact in an oxidizing atmosphere such as, for example, air, at 1,400 and 1,600° C., more preferably at 1,550 to 1,600° C. for 2 hours, and then heating the sintered compact at a temperature lower than the sintering temperature by from 50 to 250° C., e.g., by 100° C., for at least 12 hours, preferably for 24 hours. A dielectric resonator comprising the dielectric material of the present invention is also disclosed.

Claims

1. A dielectric material comprising a complex metal oxide having a perovskite crystal structure wherein the complex metal oxide contains:

a first metal oxide wherein the metal comprises Ba and at least two metals selected from Zn, Ta, and a metal Q, wherein Q is selected from the group consisting of Mg, Ca, Sr, La, B, Al, Ga, Ti, Zr, Hf, V, Nb, Si, Sn, Sb, Mn, Fe, Co, W, and Ni; and

a second metal oxide wherein the metal comprises K and Ta.

2. The dielectric material of claim 1, wherein Q is selected from the group consisting of Mg, Zr, Ga, Ni, Nb, and Sn.

3. The dielectric material of claim 1, wherein the first metal oxide comprises Ba, Ta and at least one metal selected from Zn and Q.

4. The dielectric material of claim 1, wherein the first metal oxide comprises Zn and Ta.

5. The dielectric material of claim 1, wherein the molar ratio of (i) Ba to (ii) the sum of the two metals selected from Zn, Ta, and Q in the first metal oxide is about 1:

1.

6. The dielectric material of claim 5, wherein the first oxide is Ba(Zn_1/3 Ta_2/3)O₃.

7. The dielectric material of claim 6, wherein the second metal oxide is a potassium tantalum oxide.

8. The dielectric material of claim 7, wherein the dielectric material comprises 99.9-80 mol % Ba(Zn_1/3 Ta_2/3)O₃ and 0.1-20 mol % of a potassium tantalum oxide;

and

wherein the molar ratio of potassium to tantalum in the potassium tantalum oxide ranges from 0.60;

1 to 2.00;

1.

9. The dielectric material of claim 8, wherein the molar ratio of potassium to tantalum in the potassium tantalum oxide ranges from 1.00:

1 to 2.00;

1.

10. The dielectric material of claim 7, wherein the dielectric material comprises 99.9-85 mol % Ba(Zn_1/3 Ta_2/3)O₃ and 0.1-15 mol % of a potassium tantalum oxide;

and

wherein the molar ratio of potassium to tantalum in the potassium tantalum oxide ranges from 0.60;

1 to 2.00;

1.

11. The dielectric material of claim 10, wherein the molar ratio of potassium to tantalum in the potassium tantalum oxide ranges from 1.00:

1 to 2.00;

1.

12. A complex metal oxide having a perovskite crystal structure wherein the complex metal oxide consists essentially of:

a first metal oxide wherein the metal consists of Ba and at least two metals selected from Zn, Ta, and a metal Q, wherein Q is selected from the group consisting of Mg, Ca, Sr, La, B, Al, Ga, Ti, Zr, Hf, V, Nb, Si, Sn, Sb, Mn, Fe, Co, W, and Ni; and

a second metal oxide wherein the metal consists of K and Ta.

13. The complex metal oxide of claim 12, wherein Q is selected from the group consisting of Mg, Zr, Ga, Ni, Nb, and Sn.

14. The complex metal oxide of claim 12, wherein the first metal oxide comprises Ta and at least one metal selected from Zn and Q.

15. The complex metal oxide of claim 12, wherein the first metal oxide comprises Zn and Ta.

16. The complex metal oxide of claim 12, wherein the molar ratio of (i) Ba to (ii) the sum of the two metals selected from Zn, Ta, and Q in the first metal oxide is about 1:

1.

17. The complex metal oxide of claim 16, wherein the first oxide is Ba(Zn_1/3 Ta_2/3)O₃.

18. The complex metal oxide of claim 17, wherein the second metal oxide is a potassium tantalum oxide.

19. The complex metal oxide of claim 18, wherein the dielectric material comprises 99.9-80 mol % Ba(Zn_1/3 Ta_2/3)O₃ and 0.1-20 mol % of a potassium tantalum oxide;

and

wherein the molar ratio of potassium to tantalum in the potassium tantalum oxide ranges from 0.60;

1 to 2.00;

1.

20. The complex metal oxide of claim 19, wherein the molar ratio of potassium to tantalum in the potassium tantalum oxide ranges from 1.00:

1 to 2.00;

1.

21. The complex metal oxide of claim 18, wherein the dielectric material comprises 99.9-85 mol % Ba(Zn_1/3 Ta_2/3)O₃ and 0.1-15 mol % of a potassium tantalum oxide;

and

wherein the molar ratio of potassium to tantalum in the potassium tantalum oxide ranges from 0.60;

1 to 2.00;

1.

22. The complex metal oxide of claim 21, wherein the molar ratio of potassium to tantalum in the potassium tantalum oxide ranges from 1.00:

1 to 2.00;

1.

23. A complex oxide having a perovskite crystal structure comprising:

about 40 to about 50 wt % BaO;

about 6 to about 9 wt % ZnO;

up to about 16 wt % of a metal oxide of Mg, Zr, Ga, Ni, Nb, or Sn, or combinations thereof;

about 30 to about 49 wt %Ta₂ O₅ ; and

about 0.04 to about 2 wt % K₂ O.

24. A dielectric resonator, comprising:

a dielectric material comprising a complex metal oxide having a perovskite crystal structure wherein the complex metal oxide comprises;

a first metal oxide wherein the metal comprises Ba and at least two metals selected from Zn, Ta, and a metal Q, wherein Q is selected from the group consisting of Mg, Ca, Sr, La, B, Al, Ga, Ti, Zr, Hf, V, Nb, Si, Sn, Sb, Mn, Fe, Co, W, and Ni; and

a second metal oxide wherein the metal comprises K and Ta;

a metal casing enclosing the dielectric resonator; and

an insulating holder member attached to the dielectric resonator with a heat-resitive adhesive layer.

25. The dielectric resonator of claim 24, wherein Q is an element selected from the group consisting of Mg, Zr, Ga, Ni, Nb and Sn.

26. The dielectric resonator of claim 24, wherein the first metal oxide comprises Ba, Ta and at least one metal selected from Zn and Q.

27. The dielectric resonator of claim 24, wherein the first metal oxide comprises Zn and Ta.

28. The dielectic resonator of claim 24, wherein the molar ratio of (i) Ba to (ii) the sum of the two metals selected from Zn, Ta, and Q in the first metal oxide is about 1:

1.

29. The dielectric resonator of claim 28, wherein the first oxide is Ba(Zn_1/3 Ta_2/3)O₃.

30. The dielectric resonator of claim 29, wherein the second metal oxide is a potassium tantalum oxide.

31. The dielectric resonator of claim 30, wherein the dielectric material comprises 80-99.9 mol % Ba(Zn_1/3 Ta_2/3)O₃ and 0.1-20 mol % of a potassium tantalum oxide;

and

wherein the molar ration of potassium to tantalum in the potassium tantalum oxide ranges from 0.60;

1 to 2.00;

1.

32. The dielectric resonator of claim 31, wherein the molar ration of potassium to tantalum in the potassium tantalum oxide ranges from 1.00:

1 to 2.00;

1.

33. The dielectric resonator of claim 30, wherein the dielectric material comprises 85-99.9 mol % Ba(Zn_1/3 Ta_2/3)O₃ and 0.1-15 mol % of a potassium tantalum oxide;

and

wherein the molar ratio of potassium to tantalum in the potassium tantalum oxide ranges from 0.60;

1 to 2.00;

1.

34. The dielectric resonator of claim 33, wherein the molar ratio of potassium to tantalum in the potassium tantalum oxide ranges from 1.00:

1 to 2.00;

1.

35. A method of producing a complex metal oxide having a perovskite crystal structure, wherein the complex metal oxide comprises:

a first metal oxide wherein the metal comprises Ba and at least two metals selected from Zn, Ta, and a metal Q, wherein Q is selected from the group consisting of Mg, Ca, Sr, La, B, Al, Ga, Ti, Zr, Hf, V, Nb, Si, Sn, Sb, Mn, Fe, Co, W, and Ni; and

a second metal oxide wherein the metal comprises K and Ta, the method comprising the steps of;

mixing a barium compound with at least two metals selected from Zn, Ta, and a metal Q, wherein Q is selected from the group consisting of Mg, Ca, Sr, La, B, Al, Ga, Ti, Zr, Hf, V, Nb, Si, Sn, Sb, Mn, Fe, Co, W, and Ni to produce a mixture;

compacting the mixture to produce a compact;

sintering the compact at a sintering temperture of between 1,300 and 1,650°

C; and

heat-treating the compact at a temperture 50-250°

C. lower than the sintering temperture in an oxidizing atmosphere for at least 12 hours.

36. The method of claim 35, wherein Q is selected from the group consisting of Mg, Zr, Ga, Ni, Nb, and Sn.

37. The method of claim 35, wherein the sintering is conducted at a temperature of between 1,400 and 1,600°

C.

38. The method of claim 37, wherein the sintering is conducted at a temperature of between 1,550 and 1,600°

C.

39. The method of claim 35, wherein the heat treatment is conducted at a temperature 70-200°

C. lower than the sintering temperature.

40. The method of claim 39, wherein the heat treatment is conducted at a temperature 80-150°

C. lower than the sintering temperature.

41. The method of claim 35, wherein air is used as the oxidizing atmosphere.

42. The method of claim 35, wherein Q is selected from the group consisting of Mg, Zr, Ga, Ni, Nb, and Sn.

43. The method of claim 35, wherein the first metal oxide comprises Ba, Zn and Ta.

44. The method of claim 35, wherein the molar ratio of (i) Ba to (ii) the sum of the two metals selected from Zn, Ta, and Q in the first metal oxide is about 1:

1.

45. The method of claim 44, wherein the first oxide is Ba(Zn_1/3 Ta_2/3)O₃.

46. The method fo claim 45, wherein the second metal oxide is a potassium tantalum oxide.

47. The method of claim 46, wherein the complex metal oxide comprises 80-99.9 mol % Ba(Zn_1/3 Ta_2/3)O₃ and 0.1-20 mol % of a potassium tantalum oxide;

and

wherein the molar ratio of potassium to tantalum in the potassium tantalum oxide ranges from 0.60;

1 to 2.00;

1.

48. The method of claim 47, wherein the molar ratio of potassium to tantalum in the potassium tantalum oxide ranges from 1.00:

1 to 2.00;

1.

49. The method of claim 46, wherein the dielectric material comprises 85-99.9 mol % Ba(Zn_1/3 Ta_2/3)O₃ and 0.1-15 mol % of a potassium tantalum oxide;

and

wherein the molar ratio of potassium to tantalum in the potassium tantalum oxide ranges from 0.60;

1 to 2.00;

1.

50. The method of claim 49, wherein the molar ratio of potassium to tantalum in the potassium tantalum oxide ranges from 1.00:

1 to 2.00;

1.

51. A dielectric resonator, comprising:

a dielectric material comprising a complex metal oxide having a perovskite crystal structure wherein the complex metal oxide comprises;

about 40 to about 50 wt % BaO;

about 6 to about 9 wt % ZnO;

up to about 16 wt % of a metal oxide of Mg, Zr, Ga, Ni, Nb, or Sn, or combinations thereof;

about 30 to about 49 wt % Ta₂ O₅ ; and

about 0.04 to about 2 wt % K₂ O;

a metal casing enclosing the dielectric resonator; and

an insulating holder member attached to the dielectric resonator with a heat-resistive adhesive layer.