Manufacture of .gamma.-iron(III) oxide
AssigneeBASF SE
InventorsEduard Schoenafinger, Bernd Leutner
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Abstract
A process for the manufacture of acicular .gamma.-iron(III) oxide of improved crystallinity and high coercive force by heating goethite or acicular alpha-iron(III) oxide particles at temperatures of from 500.degree. to 800.degree. C, reduction of the resulting product at temperatures of from 280.degree. to 600.degree. C and subsequent oxidation of the magnetite to .gamma.-iron(III) oxide of improved crystallinity and high coercive force.
Claims4
In a process for the manufacture of acicular .gamma.-iron(III) oxide of improved crystallinity and high coercive force by heating goethite or acicular .gamma.-iron(III) oxide at a temperature of from 500.degree. to 800.degree. C, reducing the resulting product to magnetite at a temperature of from 280.degree. to 600.degree. C and subsequently oxidizing the magnetite to .gamma.-iron(III) oxide, the improvement which comprises adding heat to the magnetite in an inert gas atmosphere to maintain a temperature of from 400.degree. to 600.degree. C after the reduction step has been completed.
Dependencies are inferred from the claim text.