Electronically tunable ceramic materials including tunable dielectric and metal silicate phases

• US 6,514,895 B1
• Filed: 06/15/2000
• Issued: 02/04/2003
• Est. Priority Date: 06/15/2000
• Status: Expired due to Term

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Paratek Microwave Incorporated (Blackberry Limited)
• Inventors: Chiu, Luna H., Zhang, Xubai, Sengupta, Louise
• Primary Examiner(s): GROUP, KARL E
• Application Number:
  US09/594,837
• Time in Patent Office: 964 Days
• Field of Search: 501/137, 501/138, 501/139
• US Class Current: 501/137
• CPC Class Codes: C04B 2111/00844 for electronic applications
• CPC Class Codes: C04B 35/04 based on magnesium oxide
• CPC Class Codes: C04B 35/16 based on silicates other than clay zircon C04B35/48
• CPC Class Codes: C04B 35/465 based on alkaline earth metal titanates
• CPC Class Codes: C04B 41/009 characterised by the material treated
• CPC Class Codes: C04B 41/4539 as a emulsion, dispersion or suspension
• CPC Class Codes: C04B 41/5024 Silicates C04B41/5022 takes precedence; silico-fluorides C04B41/5018
• CPC Class Codes: C04B 41/5041 Titanium oxide or titanates
• CPC Class Codes: C04B 41/87 Ceramics
• CPC Class Codes: H01P 1/181 using ferroelectric devices
• CPC Class Codes: H01Q 3/44 varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element

Abstract

The present invention relates to electronically tunable dielectric materials which have favorable properties for many applications, including the area of radio frequency (RF) engineering and design. The electronically tunable materials include an electronically tunable dielectric phase such as barium strontium titanate in combination with a metal silicate phase such as Mg₂SiO₄. The electronically tunable materials may be provided in bulk, thin film and thick film forms for use in devices such as phased array antennas, tunable filters and the like.

Claims

1. An electronically tunable dielectric material comprising;

at least one electronically tunable dielectric phase comprising barium strontium titanate; and

at least one metal silicate phase comprising a silicate of at least one metal selected from Be, Mg, Ca, Sr, Ba, Ra, Li, Na, K, Rb, Cs, Al, Zr, Zn, Fr, B, Fe, Mn, Cu, Ce, Cr, La, Y, Ti, Ta, Nb, Mo, W, Ni, Pd, Pb and Bi, wherein the metal silicate comprise from about 5 to about 65 weight percent of material.

2. The electronically tunable dielectric material of claim 1, wherein the metal silicate phase comprises a silicate of at least one metal selected from Mg, Ca, Sr and Ba.

3. The electronically tunable dielectric material of claim 1, wherein the metal silicate phase comprises Mg₂SiO₄, CaSiO₃, BaSiO₃ and/or SrSiO₃.

4. The electronically tunable dielectric material of claim 1, wherein the barium strontium titanate is of the formula Ba_xSr₁₋

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

5. The electronically tunable dielectric material of claim 1, wherein the metal silicate comprises from about 10 to about 50 weight percent of the material.

6. The electronically tunable dielectric material of claim 1, further comprising up to about 10 weight percent of at least one additional oxide material selected from oxides of Ba, Mg, Zr, Ca, Fe, Sr, Nb, Ta, Cr, Sn, Mn, W, Al, Ti, Na, K, Nd, Pr, Y and La.

7. The electronically tunable dielectric material of claim 1, wherein the material has a tunability of at least 10 percent at 8 V/micron.

8. The electronically tunable dielectric material of claim 1, wherein the material has a tunability of at least 25 percent at 8 V/micron.

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

mixing particles of at least one electronically tunable dielectric material and particles of at least one metal silicate material, wherein the electronically tunable dielectric material comprises barium strontium titanate, the metal silicate material comprises a silicate of at least one metal selected from Be, Mg, Ca, Sr, Ba, Ra, Li, Na, K, Rb, Cs, Al, Zr, Zn, Fr, B, Fe, Mn, Cu, Ce, Cr, La, Y, Ti, Ta, Nb, Mo, W, Ni, Pd, Pb and Bi, and the metal silicate comprises from about 5 to about 65 weight percent of the material; and

sintering the material.

10. The method of claim 9, wherein the electronically tunable dielectric particles and the metal silicate particles have average particle sizes of from about 0.1 to about 5 micron.

11. The method of claim 9, wherein the electronically tunable dielectric particles and the metal silicate particles have average particle sizes of from about 1.5 to about 2.5 micron.

12. The method of claim 9, wherein the metal silicate material comprises a silicate of at least one metal selected from Mg, Ca, Sr and Ba.

13. The method of claim 9, wherein the metal silicate material comprises Mg₂SiO₄, CaSiO₃, BaSiO₃ and/or SrSiO₃.

14. The method of claim 9, wherein the barium strontium titanate is of the formula Ba_xSr₁₋

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

15. The method of claim 9, wherein the metal silicate comprises from about 10 to about 50 weight percent of the sintered mixture.

16. The method of claim 9, further comprising adding up to about 10 weight percent of at least one additional oxide material selected from oxides of Ba, Mg, Zr, Ca, Fe, Sr, Nb, Ta, Cr, Sn, Mn, W, Al, Ti, Na, K, Nd, Pr, Y and La to the electronically tunable dielectric and metal silicate particles.

17. The method of claim 9, wherein the sintered mixture has a tunability of at least about 10 percent at 8 V/micron.

18. The method of claim 9, wherein the sintered mixture has a tunability of at least about 25 percent at 8 V/micron.