Title: Method of increasing the coercivity of magnetite films

Abstract: A method of increasing the coercivity of a magnetic device having a magnetite film reduced from alpha ferric oxide. The alpha ferric oxide film is reduced to magnetite by subjecting it to a temperature greater than 400.degree. C in a reducing atmosphere. The temperature of the film is then changed to between about 150.degree. and 300.degree. C, and the reducing atmosphere is replaced by an oxidizing atmosphere. The film is subjected to the oxidizing atmosphere while the temperature is held between 150.degree. and 300.degree. C, thus causing the magnetite film to become partially oxidized to form a solid solution of magnetite and gamma ferric oxide as represented by the formula, (1-x)Fe.sub.3 O.sub.4 .sup.. xFe.sub.2 O.sub.3, where x is between 0.49 and 0.85.

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Inventors: Chen, Shih-Lu (Painted Post, NY, US)
Murphy, James A. (Painted Post, NY, US)

Application Number: 257336
Filing Date: 1972-05-26
Publication_date: 1976-12-07
Assignee: Corning Glass Works (Corning, NY)
Primary Class(es): 427/129 427/130
Other Classes:
US Patent Ref:

2919207	Dec, 1959	Scholzel	117/235.
3031338	Apr, 1962	Bourdeau	117/107.
3620841	Nov, 1971	Comstock	117/235.
3634137	Jan, 1972	Akashi et al.	117/235.
3647661	Mar, 1972	Matsushita	117/235.
3652334	Mar, 1972	Abeck et al.	117/235.
3653962	Apr, 1972	Akashi et al.	117/235.
3703411	Nov, 1972	Melezoglu	117/235.
3795542	Mar, 1974	Halaby	117/49.

Other Refs:
Primary Examiner: Pianalto, Bernard D.
Assistant Examiner:
Attorney: Zebrowski; Walter S., Patty, Jr.; Clarence R.