Ceramic ferroelectric material

• US 5,312,790 A
• Filed: 06/09/1993
• Issued: 05/17/1994
• Est. Priority Date: 06/09/1993
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Gilde, Gary, Sengupta, Louise C., Ngo, Eric, Stowell, Steven, Lancto, Robert
• Primary Examiner(s): Bell, Mark L.
• Assistant Examiner(s): JONES, DEBORAH D
• Application Number:
  US08/076,291
• Time in Patent Office: 342 Days
• Field of Search: 501/137, 501/153
• US Class Current: 522/127
• CPC Class Codes: C04B 35/117 Composites
• CPC Class Codes: C04B 35/465 based on alkaline earth metal titanates
• CPC Class Codes: C04B 35/49 containing also titanium oxides or titanates
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 3/36 with variable phase-shifters

Abstract

A novel ceramic ferroelectric material having a low dielectric constant, loss and high tunability. The material is a composite comprising Barium Strontium Titanate (BSTO) and a ceramic material having a low dielectric constant. The preferred composite is represented by Ba_1-x Sr_x TiO₃ -Al₂ O₃, wherein x is greater than 0.00, but less than or equal to 0.70, and wherein the percent weight ratio between Ba_1-x Sr_x TiO₃ and Al₂ O₃ ranges from approximately 99%-40% and 1%-60%, respectively. The novel materials possess superior electronic properties; and they may be employed in various antenna systems.

Claims

1. A ceramic ferroelectric composite material consisting essentially of

Barium Strontium Titanate, said Barium Strontium Titanate represented as Ba_1-x Sr_x TiO₃, wherein x is greater than 0.0 but less than or equal to 0.70;

and

alumina;

wherein said Barium Strontium Titanate and alumina are present in amounts to provide a composite having a low dielectric constant, low loss tangent and high tunability.

2. The ceramic ferroelectric composite material of claim 1, wherein said Barium Strontium Titanate is Ba_1-x Sr_x TiO₃, wherein x=0.35 to 0.40.

3. The ceramic ferroelectric composite material of claim 2, wherein the weight ratio of said Barium Strontium Titanate to alumina ranges from approximately 99%-40% Barium Strontium Titanate to approximately 1%-60% alumina.

4. The ceramic ferroelectric composite material of claim 3, wherein the ratio of Barium Strontium Titanate to alumina is approximately 70% wt. Barium Strontium Titanate to approximately 30% wt. alumina.