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Preparing A Nickel-iron Ferrite

IP.com Disclosure Number: IPCOM000098070D
Original Publication Date: 1961-Dec-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Shafer, MW: AUTHOR

Abstract

The method prepares nickel-iron ferrites with the spinel structure in which the iron nickel ratio is between 0.5 and 2.0, and the metal to oxygen ratio is about 3 to 4. In the iron nickel oxygen ternary diagram, the composition lies on the line between points a and b.

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Preparing A Nickel-iron Ferrite

The method prepares nickel-iron ferrites with the spinel structure in which the iron nickel ratio is between 0.5 and 2.0, and the metal to oxygen ratio is about 3 to 4. In the iron nickel oxygen ternary diagram, the composition lies on the line between points a and b.

The nickel iron ferrite is prepared by coprecipitating the iron and nickel either as hydroxides, oxalates, or carbonates, filtering, washing, and drying at 110 degrees C. The resulting washed precipitate should have an iron-nickel ratio within the limits described. The dried material is then put in inert containers (Au, Ag, or Pt) and placed in steel pressure vessels, connected to a pressurized oxygen source. A small quantity of water, 5 to 8 drops, is added to the pressure vessel before the oxygen is introduced. The oxygen is then introduced at the desired pressure and the vessel sealed by means of a valve. It is then heated to the desired temperature for about 200 to 300 hours.

The amount of nickel III which goes into the spinel lattice is a function of both the temperature and oxygen pressure. At 1900 psi, the maximum pressure available, and at 375 degrees C, a spinel is formed in which approximately 40% of the nickel is present in the oxidation state of three. As the temperature is increased to about 125O degrees C this percentage decreases to zero. A similar decrease in the nickel III concentration is obtained by isothermally decreasing the oxygen pressure.

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