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Major phase transformations and magnetic property changes caused by electromagnetic fields at microwave frequencies

Published online by Cambridge University Press:  31 January 2011

Rustum Roy ,
Ramesh Peelamedu ,
Craig Grimes ,
Jiping Cheng  and
Dinesh Agrawal
Rustum Roy*
Affiliation:
Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802
Ramesh Peelamedu
Affiliation:
Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802
Craig Grimes
Affiliation:
Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802
Jiping Cheng
Affiliation:
Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802
Dinesh Agrawal
Affiliation:
Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802
*
a)Address all correspondence to this author.102A Materials Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802.rroy@psu.edu
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Abstract

We demonstrate in this paper that common crystalline phases can be made noncrystalline and hard magnets can be converted to soft magnets in the solid state in several seconds at temperatures far below the melting points. New crystal structures and magnetic structures of ferromagnetic oxides (ferrites such as BaFe12O19, CoFe2O4, Fe3O4, and ZnFe2O4, etc.) are formed by reacting either the stoichiometric mixture of oxides or the preformed phase-pure crystalline material in a pure H field (or E field) at microwave (2.45 GHz) frequencies. These major changes in the magnetic properties as well as major structural phase changes are caused by the magnetic field.

Type
Rapid Communications
Information
Journal of Materials Research , Volume 17 , Issue 12 , December 2002 , pp. 3008 - 3011
Copyright
Copyright © Materials Research Society 2002

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