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Self-Assembled Structures of Gas-Phase Prepared FePt Nanoparticles

Published online by Cambridge University Press:  15 March 2011

Bernd Rellinghaus
Affiliation:
Experimentelle Tieftemperaturphysik and Sonderforschungsbereich 445, Gerhard-Mercator-Universität, D-47048 Duisburg, Germany
Sonja Stappert
Affiliation:
Experimentelle Tieftemperaturphysik and Sonderforschungsbereich 445, Gerhard-Mercator-Universität, D-47048 Duisburg, Germany
Mehmet Acet
Affiliation:
Experimentelle Tieftemperaturphysik and Sonderforschungsbereich 445, Gerhard-Mercator-Universität, D-47048 Duisburg, Germany
Eberhard F. Wassermann
Affiliation:
Experimentelle Tieftemperaturphysik and Sonderforschungsbereich 445, Gerhard-Mercator-Universität, D-47048 Duisburg, Germany
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Abstract

We report on a non-lithographic method for the preparation of self-assembled FePt nanoparticles via inert-gas condensation. Prior to deposition the particles can be sintered in flight at temperatures as high as TS = 1273 K. Whereas un-sintered particles have irregular shapes, particles sintered at elevated temperatures TS ≥ 793 K show a regular faceting. (High resolution) transmission electron microscopy ((HR)TEM) shows that these regularly faceted particles are of icosahedral structure. When being deposited onto amorphous carbon films, the gas-phase sintered particles are found to have a high mobility. In particular, for the high-temperature sintered FePt nanoparticles, we observe that this mobility leads to the formation of particle arrays with hexagonal close-packed arrangements. Within these ordered patches, the particles are separated from one another. Analytical investigations using energy filtered TEM (EFTEM) show that a carbon layer is formed between the particles. Magnetization analyses give results showing that the gas-phase sintered particles are superparamagnetic at room temperature with a blocking temperature of TB = 49K.

Type
Research Article
Copyright
Copyright © Materials Research Society 2002

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