Cog dielectric with high K

• US 5,238,673 A
• Filed: 05/26/1992
• Issued: 08/24/1993
• Est. Priority Date: 11/16/1990
• Status: Expired due to Term

• 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): GALLO, CHRISTOPHER
• Application Number:
  US07/889,011
• Time in Patent Office: 455 Days
• Field of Search: 501/137, 501/138, 501/139, 423/77, 423/85, 423/598
• US Class Current: 423/598
• CPC Class Codes: C04B 35/462 based on titanates
• CPC Class Codes: H01G 4/1254 based on niobium or tungsteen, tantalum oxides or niobates, tantalates

Abstract

A composition consisting essentially of 60.0-70.0 mol % TiO₂, 14.3-20.0 mol % Nd₂ O₃, 11.0-16.7 mol % BaO, 1.0-8.0 mol % ZrO₂ and 0.05-0.30 mol % CeO₂. This composition is useful for forming densified ceramic dielectric bodies having a dielectric constant of at least 65 and which meet COG specifications, and multilayer capacitors that contain such dielectric bodies.

Claims

1. A process for preparing finely divided particles of a composition consisting essentially of:

(a) 60.0-70.0 mol % TiO₂ ;

(b) 14.3-20.0 mol % Nd₂ O₃ ;

(c) 11.0-16.7 mol % BaO;

(d) 1.0-8.0 mol % ZrO₂ ; and

(e) 0.05-0.30 mol % CeO₂.

comprising the steps of;

(a) admixing a chelating solution comprising a chelating agent and solvent with metal compounds TiX_n, NdX_n, ZrX_n and CeX_n wherein each X is independently selected from the group consisting of HCO₂ --, CH₃ CO₂ --, ^- OH, -OR, ^- NO₃ and ^- Cl, R is alkyl, and n is 3 or 4;

(b) mixing in a high turbulence energy environment the metal chelate admixture and an alkaline solution containing Ba²⁺, the pH of the resultant mixture being greater than 11;

(c) heating the product of step (b) at 90°

-105°

C. for at least 3 hours;

(d) isolating, washing and drying the metal oxide product of step (c);

(e) granulating and calcining the resultant powder at a temperature in the range of 850°

-1150°

C.

2. The process of claim 1 wherein the chelating agent consists essentially of alpha-hydroxycarboxylic acids and alphaaminocarboxylic acids.

3. The process of claim 2 wherein the chelating agent is selected from the group consisting of lactic acid, glycolic acid, malic acid, citric acid, ethylene diamine tetracetic acid and glycine.

4. The process of claim 1 wherein the solvent consists essentially of deionized water, and mixtures of deionized water with methanol, ethanol, isopropanol, or acetic acid.

5. A process for preparing finely divided particles of a composition consisting essentially of:

(a) 60.0-70.0 mol % TiO₂ ;

(b) 14.3-20.0 mol % Nd₂ O₃ ;

(c) 11.0-16.7 mol % BaO;

(d) 1.0-8.0 mol % ZrO₂ ; and

(e) 0.05-0.30 mol % CeO₂.

said process comprising the steps of;

(a) admixing an aqueous solvent with metal compounds Ti(OCl)₂, Zr(OCl)₂, NdNO₃ and CeNO₃ ;

(b) mixing in a high turbulence energy environment the metal admixture of step (a) and an alkaline solution containing Ba²⁺, the pH of the resultant slurry being in the range of 1-3;

(c) adding sufficient base to the slurry of step (b) to raise the pH to greater than 11, thereby precipitating product;

(d) heating the product of step (c) at 90°

-105°

C. for at least 3 hours;

(e) isolating the metal oxide product of step (d);

(f) calcining at a temperature in the range of 850°

-1150°

C. and granulating the isolated product from step (e).

6. The process of claim 5 wherein the solvent consists essentially of deionized water, and mixtures of deionized water with methanol, ethanol, isopropanol, or acetic acid.