High K dielectric compositions with fine grain size

• US 5,155,072 A
• Filed: 06/29/1990
• Issued: 10/13/1992
• Est. Priority Date: 06/29/1990
• Status: Expired due to Fees

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Burn, Ian, Bruno, Salvatore A.
• Primary Examiner(s): Bell, Mark L.
• Assistant Examiner(s): Green, Anthony J.
• Application Number:
  US07/564,586
• Time in Patent Office: 837 Days
• Field of Search: 501/137, 501/138, 501/139
• US Class Current: 501/138
• CPC Class Codes: C04B 35/4682 based on BaTiO3 perovskite phase
• CPC Class Codes: H01G 4/1218 based on titanium oxides or titanates H01G4/1245 takes precedence
• CPC Class Codes: H05K 1/0306 Inorganic insulating substrates, e.g. ceramic, glass

Abstract

A composition comprising finely divided particles of modified barium titanate; and an admixture of calcium, titanium and manganese; the modified barium titanate particles containing Zr, Zn and Nb homogeneously distributed on an atomic scale throughout the particles according to the formula:

BaTi.sub.1-(x+3y/2) (Zr.sub.x Zn.sub.y/2 Nb.sub.y) O.sub.3

wherein x=0.01-0.20 and y=0.005-0.075. This composition forms a dielectric layer having a Curie Temperature below 25° C., a dielectric constant of at least 10,000 and grain size of 5 microns or less and is useful in multilayer electrical devices such as circuits and capacitors.

Claims

1. A composition for forming a densified dielectric body having a Curie Temperature below 25°

C., a dielectric constant of at least 10,000 and grain size of 5 microns or less, the composition compirising;

(a) finely divided particles of modified barium titanate; and

(b) an admixture of (1) oxides of calcium, and titanium, precursors thereof, or calcium titanate and (2) manganese oxide, precursors thereof, barium manganate or calcium manganate;

the admixture comprising in wt. % of the composition;

3. The composition of claim 1 wherein the admixture of oxides or precursors thereof is coated on the surface of the modified barium titanate particles.

5. The composition of claim 1 further comprising a zinc borate fluxing agent.

6. The composition of claim 1 further comprising an organic medium containing a solution of volatile organic solvent and organic polymeric binder.

7. A dielectric sheet comprising a cast layer of the composition of claim 5 which has been heated to remove the volatile organic solvent.

8. A dielectric ceramic layer comprising the sheet of claim 6 which has been fired to volatilize the organic medium therefrom and to densify the inorganic components by sintering.

2. 25-5.0 wt. % CaO;

0.25-5.0 wt. % TiO₂ ; and

0.025-0.20 wt. % MnO;

the modified barium titanate particles containing Zr, Zn and Nb homogeneously distributed on an atomic scale throughout the particles according to the formula;

space="preserve" listing-type="equation">BaTi.sub.1-(x+3y/2) (Zr.sub.x Zn.sub.y/2 Nb.sub.y)O.sub.3

wherein

x =0.01-0.20 and

y =0.005-0.075.

4. The composition of claim 2 wherein x =0.07 and y =0.027.