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Transmission electron microscopy study of barium hexaferrite formation from barium carbonate and hematite

Published online by Cambridge University Press:  31 January 2011

Hanns P. Steier ,
Joaquin Requena  and
José S. Moya
Hanns P. Steier
Affiliation:
Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049 Madrid, Spain
Joaquin Requena
Affiliation:
Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049 Madrid, Spain
José S. Moya
Affiliation:
Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049 Madrid, Spain
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Abstract

The formation of barium hexaferrite from stoichiometric mixtures of BaCO3 and Fe2O3 has been investigated by means of differential thermal analysis and thermogravimetry, x-ray diffraction, and transmission electron microscopy–energy dispersive spectrometry. The first step, which implies decarbonatation and monoferrite formation, includes the formation of various intermediate compounds, which are formed at contact points between BaCO3 and Fe2O3 grains, and implies diffusion of both species. In the second step, barium hexaferrite is formed at interfaces between monoferrite and iron oxide mainly by diffusion of barium through the BF6 lattice into the hematite lattice. This exothermic reaction process leads to nonagglomerated pseudohexagonal platelets with an average particle size very close to the one of the starting powder mixture (∼1 μm).

Type
Articles
Information
Journal of Materials Research , Volume 14 , Issue 9 , September 1999 , pp. 3647 - 3652
Copyright
Copyright © Materials Research Society 1999

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References

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