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Microstructural defects in γ-Fe2O3 particles

Published online by Cambridge University Press:  31 January 2011

Ernest L. Hall  and
Ami E. Berkowitz
Ernest L. Hall
Affiliation:
General Electric Company, Corporate Research and Development, Schenectady, New York 12301
Ami E. Berkowitz*
Affiliation:
General Electric Company, Corporate Research and Development, Schenectady, New York 12301
*
a)Present adress: Center for Magnetic Recording Rescarch, R-001, University of California, San Diego, La Jolla, California 92093.
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Abstract

The microstructure of three different types of γ-Fe2O3 particles were examined using transmission electron microscopy. These included pure γ-Fe2O3, γ-Fe2O3 that had been surface modified using Co, and γ-Fe2O3 that had been doped with Co. The major internal microstructural defects found in the particles in all of the samples were pores and antiphase boundaries. Some particles also had a very high density of dislocations and low-angle boundaries. In general, the particles could be described as single crystals with symmetric cross section. The structure is based on a tetragonal unit cell, and each particle is divided into antiphase domains in which the c axis is oriented at 90°with respect to adjoining domains. The particles often exhibited very irregular shapes. No effect of Co modification was seen on the internal or surface structure of the particles. The Co-doped particles were found to be smaller in size and contained a lower density of internal defects. The effect of the microstructural defects and morphological irregularities in these particles on magnetic behavior is discussed.

Type
Articles
Information
Journal of Materials Research , Volume 1 , Issue 6 , December 1986 , pp. 836 - 844
Copyright
Copyright © Materials Research Society 1986

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