US3894970A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preparing high temperature stable gamma iron oxide
Assignee: International Business Machines Corp
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Filing: 1973-03-26
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Granted: 1975-07-15
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Expires: 1993-03-26
Abstract
Abstract A method of making a high temperature stable ferromagnetic material comprising gamma Fe2O3 and between 0.08 to 5% by weight based on weight of Fe2O3 of a cation chosen from the group having a cation size at least substantially that of Na and less than that of Cs . Typically, the cation is chosen from the group consisting of sodium, potassium, or calcium. Magnetic and temperature stability can be achieved to temperatures in excess of 700*C before the cubic gamma magnetic brown iron oxide converts to the alpha rhombehedral red nonmagnetic iron oxide.
Inventors
- 👤 Genevieve Marie Adams
- 👤 John Irving Crowley
- 👤 Keith Harris Larson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:25
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70652; G11B5/70668
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
61 words
A METHOD OF INCREASING THE MAGNETIC AND COLOR TEMPERATURE STABILITY OF Y-FE2O3 COMPRISING THE STEPS OF MIXING Y-FE2O3 WITH A SOLUTION CHOSEN FROM THE GROUP CONSISTING OF HYDROXIDE AND PHOSPHATE OF SODIUM, POTASSIUM AND CALCIUM CONTAINING BETWEEN 0.08-5% BY EIGHT BASED ON THE WEIGHT OF FE203 OF SODIUM, POTASSIUM OR CALCIUM, AND EVAPORATING THE SOLVENT FROM THE SOLUTION OF THE MIXTURE.
Claim 2
Independent Claim
61 words
A METHOD OF INCREASING THE MAGNETIC AND COLOR TEMPERATURE STABILITY OF Y-FE2O3 COMPRISING THE STEPS OF MIXING Y-FE2O3 WITH A SOLUTION CHOSEN FROM THE GROUP CONSISTING OF HYDROXIDE AND PHOSPHATE OF SODIUM, POTASSIUM AND CALCIUM CONTAINING BETWEEN 0.08-5% BY EIGHT BASED ON THE WEIGHT OF FE203 OF SODIUM, POTASSIUM OR CALCIUM, AND EVAPORATING THE SOLVENT FROM THE SOLUTION OF THE MIXTURE.
Claim 3
Dependent Claim
12 words
The method of claim 1 wherein the solution includes an expoxy resin.
Claim 4
Dependent Claim
13 words
The method of claim 1 wherein the solution includes a synthetic polymer resin.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-07-14 | 1979-01-13 | 1979-07-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-14 | 1983-01-13 | 1983-07-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-14 | 1987-01-13 | 1987-07-15 | $7700.00 | Window Closed / Lapsed |