US4246128A
Expired / Lapsed
US
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Method of making MnZn ferrites
Assignee: AT&T Inc
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Filing: 1979-08-08
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Granted: 1981-01-20
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Expires: 1999-08-08
Abstract
Abstract Desirable properties of manganese zinc ferrites are obtained without the need for controlling or changing the oxygen partial pressure during the sintering and cooling steps by adding a small amount of germanium or gallium to the ferrite and using an atmosphere, such as air, during the sintering and cooling steps, that has at least 1 percent oxygen by volume.
Inventors
- 👤 Patrick K. Gallagher
- 👤 Ernst M. Gyorgy
- 👤 David W. Johnson, Jr.
- 👤 Murray Robbins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 06:28
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/26; C04B35/2658
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
171 words
A method of producing a manganese zinc ferrite having a relative temperature coefficient of permeability less than 0.02 percent over the temperature range from -40 degrees C. to 80 degrees C., and the atom composition Mn a Zn b A x Fe 2+d O r ; the sum of a and b is greater than or equal to 0.65 and less than or equal to 0.99; d is greater than 0.0 and less than or equal to 0.2; comprising: forming a mixture of ferrite components corresponding to said atom composition; sintering said mixture in a first atmostphere at a temperature between approximately 1150 degrees C. and 1300 degrees C.; said first atmosphere comprising at least 1 percent, by volume, oxygen; and cooling said mixture to ambient temperature in a second atmosphere CHARACTERIZED IN THAT: A is selected from the group consisting of germanium and gallium; x is greater than or equal to 0.01 and less than or equal to 0.15; said second atmosphere comprises at least 1 percent, by volume, oxygen.
Claim 2
Independent Claim
171 words
A method of producing a manganese zinc ferrite having a relative temperature coefficient of permeability less than 0.02 percent over the temperature range from -40 degrees C. to 80 degrees C., and the atom composition Mn a Zn b A x Fe 2+d O r ; the sum of a and b is greater than or equal to 0.65 and less than or equal to 0.99; d is greater than 0.0 and less than or equal to 0.2; comprising: forming a mixture of ferrite components corresponding to said atom composition; sintering said mixture in a first atmostphere at a temperature between approximately 1150 degrees C. and 1300 degrees C.; said first atmosphere comprising at least 1 percent, by volume, oxygen; and cooling said mixture to ambient temperature in a second atmosphere CHARACTERIZED IN THAT: A is selected from the group consisting of germanium and gallium; x is greater than or equal to 0.01 and less than or equal to 0.15; said second atmosphere comprises at least 1 percent, by volume, oxygen.
Claim 3
Dependent Claim
12 words
A method as recited in claim 1 in which A is germanium.
Claim 4
Dependent Claim
18 words
A method as recited in claim 2 in which d is greater than 0.03 and less than 0.1.
Claim 5
Dependent Claim
15 words
A method as recited in claim 3 in which x is between 0.025 and 0.05.
Claim 6
Dependent Claim
18 words
A method as recited in claim 2 or 4 in which said temperature is approximately 1300 degrees C.
Claim 7
Dependent Claim
21 words
A method as recited in claim 2 or 4 in which said first and second atmospheres comprise approximately 20 percent oxygen.
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) | 1984-01-20 | 1984-07-21 | 1985-01-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-20 | 1988-07-21 | 1989-01-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-20 | 1992-07-21 | 1993-01-20 | $7700.00 | Window Closed / Lapsed |