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Phase transformation-induced tetragonal FeCo nanostructures.

Maogang Gong¹, Alec Kirkeminde, Manfred Wuttig

¹Department of Chemistry, University of Kansas , Lawrence, Kansas 66045, United States.

|October 1, 2014

Summary

Researchers developed a new method to create high-performance tetragonal iron-cobalt (FeCo) nanomagnets without rare-earth elements. This technique uses phase transformation to control structure and enhance magnetic properties for potential green energy applications.

Keywords:

Iron−cobalt alloy core/shell magnetocrystalline anisotropy nanomagnetism

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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

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Published on: June 7, 2018

Area of Science:

Materials Science
Nanotechnology
Magnetism

Background:

Tetragonal FeCo nanostructures offer high magnetocrystalline anisotropy and magnetization without rare-earth elements.
Controlling the metastable structure, size, and stoichiometry of these nanostructures is challenging.

Purpose of the Study:

To demonstrate a novel templated growth and phase transformation method for fabricating high-performance tetragonal FeCo nanostructures.
To investigate the influence of shell thickness and stoichiometry on magnetic properties.

Main Methods:

AuCu templated FeCo shell growth.
Thermally induced phase transformation of AuCu core (FCC to L10).
Experimental characterization and lattice mismatch calculations to confirm structural changes and relaxation.

Main Results:

Successfully triggered FeCo shell transformation from BCC to body-centered tetragonal phase.
Achieved high coercivity (846 Oe) and saturation magnetization (221 emu/g) in the tetragonal FeCo structure.
Identified a critical FeCo shell thickness for relaxation and confirmed shell thickness/stoichiometry dictate magnetic characteristics.

Conclusions:

The study provides a general route to fabricate high-performance metastable nanomagnets using phase transformation.
This method enables control over structure and magnetic properties of FeCo nanostructures.
Potential applications in green energy technologies are highlighted.