Method for preparation of ferrites

• US 6,193,904 B1
• Filed: 03/12/1998
• Issued: 02/27/2001
• Est. Priority Date: 03/12/1998
• Status: Expired due to Fees

• Current Assignee: Northrop Grumman Corporation
• Original Assignee: Northrop Grumman Corporation
• Inventors: Vasilow, Theodore R., Stough, Daryl R., Smith, James D. B., Schoch, Karl F. Jr.
• Primary Examiner(s): KOSLOW, CAROL M
• Application Number:
  US09/041,220
• Time in Patent Office: 1,083 Days
• Field of Search: 423/594, 252/62.56, 252/62.57, 252/62.61, 252/62.62, 252/62.67
• US Class Current: 252/62.62
• CPC Class Codes: C01G 49/009 Compounds containing, besides iron, two or more other elements, with the exception of oxygen or hydrogen
• CPC Class Codes: C01P 2002/30 Three-dimensional structures
• CPC Class Codes: C01P 2002/88 by thermal analysis data, e.g. TGA, DTA, DSC
• CPC Class Codes: C01P 2004/03 obtained by SEM
• CPC Class Codes: C01P 2006/60 Optical properties, e.g. expressed in CIELAB-values
• CPC Class Codes: C04B 35/26 based on ferrites
• CPC Class Codes: H01F 1/344 Ferrites, e.g. having a cubic spinel structure (X2+O)(Y23+O3), e.g. magnetite Fe3O4

Abstract

Methods of preparing ferrite powders for use in microwave elements such as isolators, circulators, phase shifters and transmission line elements. In one method separate precipitations of metal dicarboxylate salts such as oxalates or malonates are mixed with a ferrous dicarboxylate. This is followed by mixing and calcining of the precipitated dicarboxylates to form the ferrite powder. In another method metal acetates in a solution of concentrated acetic acidare mixed with iron powder to form a solution which is mixed with malonic acid. The resulting mixed metal malonates are processed into a powder which is calcined to obtain the ferrite. To form a lithium ferrite, lithium carbonate is added to prepared powders prior to the calcining step.

Claims

1. A method of preparing a ferrite microwave element, comprising the steps of:

(A) mixing at least two separately prepared metal dicarboxylates, at least one of which is ferrous dicarboxylate;

(B) calcining the mixed metal dicarboxylates to form said ferrite; and

(C) additionally processing said ferrite to form a microwave element.

2. A method of preparing a ferrite microwave element, comprising the steps of:

(A) mixing at least two separately prepared metal dicarboxylates, at least one of which is a rare earth metal dicarboxylate and another of which is a ferrous dicarboxylate;

(B) calcining the mixed metal dicarboxylates to form said ferrite; and

(C) additionally processing said ferrite to form a microwave element.

3. A method of preparing a ferrite powder comprising the steps of:

(A) dissolving at least first and second metal acetates in a solution of concentrated acetic acid to form a first solution;

(B) deaerating said first solution;

(C) adding iron powder to the deaerated solution;

(D) refluxing the solution;

(E) cooling the solution;

(F) deaerating a solution of oxalic acid in water;

(G) mixing the solution of oxalic acid with the first solution to form a precipitate of mixed oxalates;

(H) filtering, washing and drying the mixed oxalates precipitate to form a mixed oxalate powder;

(I) adding lithium carbonate to said mixed oxalate powder; and

(J) calcining said lithium carbonate and said mixed oxalate powder to form said ferrite.

4. A method of preparing a ferrite compound, comprising the step of:

(A) mixing at least two separately prepared metal dicarboxylates, at least one of which is ferrous dicarbonate;

(B) adding lithium carbonate powder to the mixture of step (A); and

(C) calcining the mixed metal dicarboxylates and lithium carbonate powder to form Said ferrite.

5. A method of preparing a ferrite powder comprising the steps of:

(A) dissolving a first metal acetate in water and mixing the resulting solution with a solution of an aqueous dicarboxylic acid to form a first metal dicarboxylate precipitate;

(B) filtering, washing and drying said first metal dicarboxylate precipitate to form a first metal dicarboxylate powder;

(C) separately dissolving at least a second metal acetate in water and mixing the resulting solution with a solution of an aqueous dicarboxylic acid to form at least a second metal dicarboxylate precipitate;

(D) filtering, washing and drying said at least second metal dicarboxylate precipitate to form at least a second metal dicarboxylate powder;

(E) mixing a ferrous dicarboxylate powder with said first and said at least second metal dicarboxylate powders;

(F) adding lithium carbonate powder to the mixture of step (E); and

(G) calcining the mixed powders and lithium carbonate powder to form said ferrite.

6. A method of preparing a ferrite powder comprising the steps of:

(A) dissolving at least first and second metal acetates in a solution of concentrated acetic acid to form a first solution;

(B) deaerating said first solution;

(C) adding iron powder to the deaerated solution;

(D) refluxing the solution;

(E) deaerating a solution of malonic acid in water;

(F) mixing the solution of malonic acid with the first solution to form a precipitate of mixed malonates;

(G) cooling the results of step (F);

(H) filtering, washing and drying the mixed malonate precipitate to form a mixed malonate powder;

(I) adding lithium carbonate powder to the mixed malonate powder; and

(J) calcining the mixed malonate powder and lithium carbonate powder to form said ferrite.