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Producing Magnetic Particles With Good Characteristics

IP.com Disclosure Number: IPCOM000083832D
Original Publication Date: 1975-Aug-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Larson, TL: AUTHOR

Abstract

It is desirable that magnetic particles which are to be utilized in producing magnetic recording media exhibit certain characteristics. These characteristics include high coercivity, high-squareness ratio, high-magnetic moment and other properties. It is not unusual for magnetic cobalt-phosphorus particles produced by chemical reduction, to exhibit less than completely desirable properties for each of these characteristics.

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Producing Magnetic Particles With Good Characteristics

It is desirable that magnetic particles which are to be utilized in producing magnetic recording media exhibit certain characteristics. These characteristics include high coercivity, high-squareness ratio, high-magnetic moment and other properties. It is not unusual for magnetic cobalt-phosphorus particles produced by chemical reduction, to exhibit less than completely desirable properties for each of these characteristics.

It has now been determined that control of the reaction time involved in the production of the particles has an effect upon these characteristics. For example, where cobalt-phosphorus particles are produced from a heated cobalt cation, hypophosphite anion aqueous bath, in which the pH is controlled with ammonium hydroxide, decreased reaction time results in particles exhibiting improved magnetic properties.

For example, in a given reaction bath, wherein the particle formation reaction was allowed to proceed for 140 seconds, the resulting cobalt-phosphorus particles showed a squareness ratio of 0.25 and a coercivity of about 356 oersteds. When the same bath was prepared and allowed to react for only 20 seconds, the squareness ratio was found to have increased to 0.36 and the coercivity to have increased to 497 oersteds. It is, therefore, seen that both the coercivity and squareness ratio of cobalt-phosphorus particles can be increased by decreasing the reaction time.

Reaction time is contro...