Ceramic ferroelectric composite material-BSTO-ZnO

• US 5,635,433 A
• Filed: 09/11/1995
• Issued: 06/03/1997
• Est. Priority Date: 09/11/1995
• Status: Expired due to Term

• Current Assignee: United States Secretary of the Army
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Sengupta, Louise
• Primary Examiner(s): Jones, Deborah
• Assistant Examiner(s): TROILO, LOUIS
• Application Number:
  US08/528,626
• Time in Patent Office: 631 Days
• Field of Search: 501/137, 501/138
• US Class Current: 501/137
• CPC Class Codes: C04B 35/453 based on zinc, tin, or bismuth oxides or solid solutions thereof with other oxides, e.g. zincates, stannates or bismuthates
• CPC Class Codes: C04B 35/465 based on alkaline earth metal titanates

Abstract

A novel ceramic ferroelectric material having a high dielectric constant, aow loss tangent, a low threshold voltage, a high nonlinear voltage exponent and a high tunability. The material is a composite comprising Barium Strontium Titanate (BSTO) and zinc oxide (ZnO). The preferred composite is represented by Ba_1-x Sr_x TiO₃ --ZnO, wherein x is greater than 0.00, but less than or equal to 0.75, and wherein the percent weight ratio between BSTO and ZnO ranges from approximately 99%-50% and 1%-50% respectively. The novel materials possess superior electronic properties, and they may be employed in multilayer capacitors, capacitor-varistors, non-volatile computer memory or phased array antenna systems.

Claims

1. A ceramic Ferroelectric composite material BSTO-ZnO material consisting of;

Barium Strontium Titanate, said barium Strontium Titanate represented as Ba_1-x Sr_x TiO₃, wherein said x is greater than 0.0 but less than or equal to 0.75;

and zinc oxide represented as ZnO;

wherein the weight ratio of said Barium Strontium Titanate to zinc oxide ranges from approximately 99-50% wt. said Barium Strontium Titanate to approximmately 1%-50% wt. said zinc oxide.

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

3. The ceramic ferroelectric composite material-BSTO-ZnO according to claim 1, wherein the ratio of said Barium Strontium Titanate to said zinc oxide is approximately 70% wt. said Barium Strontium Titanate to approximately 30% wt. said zinc oxide.

4. The ceramic ferroelectric composite material-BSTO-ZnO according to claim 1, wherein the weight ratio of said Barium Strontium Titanate to said zinc oxide ranges from approximately 99%-85% wt. said Barium Strontium Titanate to approximately 1%-15% wt. said zinc oxide for use in phased array antenna systems.

5. The ceramic ferroelectric composite material BSTO-ZnO according to claim 1, wherein the weight ratio of said Barium Strontium Titanate to said zinc oxide ranges from approximately 85%-50% wt. said Barium Strontium Titanate to approximately 15%-50% Wt. said zinc oxide for use in a capacitor-varistor protection device for microelectric circuits;

wherein said Barium Strontium Titanate and said zinc oxide are present in an amount to provide a composite having a a high dielectric constant of from approximately 3500 to 110,000; and

a low loss tangent of 0.5 or less;

a low threshold voltage of between 5-100 volts;

a high nonlinear voltage exponent, and

and high tunability ranging from 4 to 50%.