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Preparation of Fe(2)O(3) Needles by Decomposition of Iron Salt

IP.com Disclosure Number: IPCOM000050559D
Original Publication Date: 1982-Nov-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

McLachlan, DS: AUTHOR

Abstract

Various salts can be decomposed by heat or can react chemically with the surrounding atmosphere to form a metal or an oxide. An example of an oxide-forming salt is a hydrate of iron nitrate which is molten at about 50 degrees C and decomposes at about 200 degrees C. Decomposition in an oxygen atmosphere should ensure the formation of the higher oxide.

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Preparation of Fe(2)O(3) Needles by Decomposition of Iron Salt

Various salts can be decomposed by heat or can react chemically with the surrounding atmosphere to form a metal or an oxide. An example of an oxide- forming salt is a hydrate of iron nitrate which is molten at about 50 degrees C and decomposes at about 200 degrees C. Decomposition in an oxygen atmosphere should ensure the formation of the higher oxide.

For magnetic recording purposes the Fe(2)O(3) should be in needle form. This may be accomplished by methods as follows:
1. By injecting a fine stream (of a pre-selected diameter) of

the salt (molten or in aqueous solution) into a furnace

(containing oxygen, if necessary) where it decomposes into

a fine wire of Fe(2)O(3) which is broken into needles later.
2. If difficulties (such as unavoidable formation of droplets)

are experienced in the above method, an alternate method is

to cause decomposition to occur by directing a stream

against

a hot spinning drum (or between hot anvils). The nature of

the stream and the decomposition surface determines the size

and shape of the pieces of Fe(2)O(3) produced. The shape

varies

from needles to platelets.
3. Another method for overcoming droplet formation is to cause

decomposition to occur inside a fine hot tube. The resulting

needles and gas are blown out the far end.
4. A further possibility is to dissolve the salt in an aqueous

photoresist. Gelatine solutions can act as photoresists.

The geometry wanted is defin...