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Alumina Doped Lithium Bearing Ferrites

IP.com Disclosure Number: IPCOM000089921D
Original Publication Date: 1968-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Gogos, B: AUTHOR [+2]

Abstract

Ferrite storage cores made from lithium-bearing ferrites are enhanced by addition of milled alumina. The addition of up to three weight percent alumina to the general formula Li(x) M(1-2x) Fe(2+x) O(4), where x = 0 - 0.1, causes an increase in switching threshold currents. These increased threshold currents produce a faster switching core. The effect is illustrated in drawing A.

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Alumina Doped Lithium Bearing Ferrites

Ferrite storage cores made from lithium-bearing ferrites are enhanced by addition of milled alumina. The addition of up to three weight percent alumina to the general formula Li(x) M(1-2x) Fe(2+x) O(4), where x = 0 - 0.1, causes an increase in switching threshold currents. These increased threshold currents produce a faster switching core. The effect is illustrated in drawing A.

In lithium-bearing ferrites of moderate to high lithium concentrations, Li at. no. = 0.2 - 0.45, the addition of up to five weight percent milled Al(2) O(3) acts to decrease the heat treatment required to produce a given threshold. The reduced heat treatment takes the form of either reduced sintering temperature or shorter firing times. Because of this reduced heat treatment, less lithia is volatilized and the ferrite is more nearly stoichiometric, drawing B.

Processing of the ferrite follows the normal ceramic technology except that the alumina particles, having been milled in a steel mill with steel balls, are homogenized with calcined and milled ferrite powder prior to the final pelletizing process. Pressing and sintering follow in the normal manner. The milling of the alumina is a necessary step, otherwise, shearing of the B-H loop occurs in these materials.

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