Influence of the Hydrogen Reduction Time and Temperature on the Morphology Evolution and Hematite/Magnetite Conversion of Spindle-Type Hematite Nanoparticles

FH – HES

Authors

  • Thierry Chappuis Ecole d'Ingénieurs et d'Architectes de Fribourg, Boulevard de Pérolles 80, CP 32 CH-1705 Fribourg, Switzerland. thierry.chappuis@hefr.ch
  • Izabela Bobowska Ecole d'Ingénieurs et d'Architectes de Fribourg, Boulevard de Pérolles 80, CP 32 CH-1705 Fribourg, Switzerland
  • Stefan Hengsberger Ecole d'Ingénieurs et d'Architectes de Fribourg, Boulevard de Pérolles 80, CP 32 CH-1705 Fribourg, Switzerland
  • Ennio Vanoli Ecole d'Ingénieurs et d'Architectes de Fribourg, Boulevard de Pérolles 80, CP 32 CH-1705 Fribourg, Switzerland
  • Hervé Dietsch University of Fribourg, Adolphe Merkle Institute, Route de l'Ancienne Papeterie, P. O. BOX 209, CH-1723 Marly 1, Switzerland. herve.dietsch@unifr.ch

DOI:

https://doi.org/10.2533/chimia.2011.979

Keywords:

Anisotropic nanoparticles, Hematite, Hybrid structure, Hydrogen reduction, Iron oxide nanoparticles, Magnetite

Abstract

We report on the transformation via hydrogen reduction of spindle-type hematite nanoparticles into hematite/magnetite hybrid iron oxide particles. The transformation process consists of the reduction of nanoparticles powder in an autoclave using hydrogen gas at a fixed pressure of 11 bars. Both temperature and time of reduction are varied between 300 °C to 360 °C and 0 to 45 h. X-Ray powder diffraction data on the obtained powder and corresponding Rietveld refinement allow the amount of reduced hematite to be determined as a function of these two parameters. Kinetics parameters are measured and an estimation of the activation energy is obtained through linearization of the Arrhenius equation. While reduction is dramatically accelerated at higher temperature, the morphology of the nanoparticles only remain qualitatively unchanged at 300 °C as seen from transmission electron microscopy images. The mechanisms underlying morphology changes are still under study and seem to be closely related to reactor pressure.

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Published

2011-12-14

How to Cite

[1]
T. Chappuis, I. Bobowska, S. Hengsberger, E. Vanoli, H. Dietsch, Chimia 2011, 65, 979, DOI: 10.2533/chimia.2011.979.