Compositions – Magnetic – Iron-oxygen compound containing
Patent
1986-11-06
1989-04-18
Garvin, Patrick P.
Compositions
Magnetic
Iron-oxygen compound containing
C01G 4906
Patent
active
048225096
ABSTRACT:
A highly magnetic isotropic iron oxide powder with a uniform particle size distribution and particle size in the range from 0.005 to 0.2 micrometer consists of a mixed iron oxide exhibiting gamma (Fe.sub.2 O.sub.3) and ferrite (Fe.sub.3 O.sub.4) structure, having the empirical formula Fe.sub.72-x O.sub.96, where x has a value between 2 to 7, an aspect ratio of at most 2:1 and a temperature coefficient of coercivity of less than -0.7% per degree Celcius. The mixed oxide is optionally a cobalt-modified mixed iron oxide containing 2-6% by weight of cobalt and is obtained by heating ultrafine, ferrite particles in a controlled, oxidizing atmosphere at a temperature of 240.degree. C. to 320.degree. C. for a period of one to three hours.
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"IEEE Transactions on Magnetics", vol. MAG-18, No. 6, 1083 (1982)-`High Coercivity Particulate Magnetic Media In-Situ Partial Reduction of gamma Fe.sub.2 O.sub.3 and Modified gamma Fe.sub.2 O.sub.3 ' by V. M. De Palma et al.
Bishara Jeries I.
Rudd Eric J.
Vaccaro Anthony J.
Eltech Systems Corporation
Fourson George R.
Freer John J.
Garvin Patrick P.
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