Issue 10, 2020

Production of Fe nanoparticles from γ-Fe2O3 by high-pressure hydrogen reduction

Abstract

In this work, the reduction of iron oxide γ-Fe2O3 nanoparticles by hydrogen at high pressures is studied. Increasing the hydrogen pressure enables reduction of γ-Fe2O3 to α-Fe at significantly lower temperatures. At low pressures, a temperature of 390 °C is necessary whereas at 530 bar complete reduction can be realized at temperatures as low as 210 °C. This leads to significant improvement in the final particle morphology, maintaining high surface-to-volume ratio of the nanoparticles with an average size of 47 ± 5 nm which is close to that of the precursor γ-Fe2O3. Neck formation, coalescence and growth during reduction can be significantly suppressed. Investigations of magnetic properties show that saturation magnetization of the reduced α-Fe nanoparticles decreases with particle size from 209 A m2 kg−1 at 390 °C reduction temperature to 204 A m2 kg−1 at 210 °C. Coercivity for the fine iron particles reaches 0.076 T which exceeds the theoretical anisotropy field. This is attributed to nano-scale surface effects.

Graphical abstract: Production of Fe nanoparticles from γ-Fe2O3 by high-pressure hydrogen reduction

Article information

Article type
Paper
Submitted
01 aug 2020
Accepted
26 aug 2020
First published
26 aug 2020
This article is Open Access
Creative Commons BY license

Nanoscale Adv., 2020,2, 4777-4784

Production of Fe nanoparticles from γ-Fe2O3 by high-pressure hydrogen reduction

I. Dirba, C. A. Schwöbel, A. Zintler, P. Komissinskiy, L. Molina-Luna and O. Gutfleisch, Nanoscale Adv., 2020, 2, 4777 DOI: 10.1039/D0NA00635A

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