Fabricating iron oxide with high phase purity

Various types of iron oxide (FeO) are typically distinguished by the number of iron and oxygen atoms coordinated with one another. However, specific iron and oxygen coordination is also an important factor to consider, as a molecule’s various phases can exhibit vastly different material properties. In recent years, epsilon-phase iron oxide (ε-Fe₂O₃), a rare polymorph of Fe₂O₃, has been a material of special interest and is receiving significant attention due to its exemplary magnetic properties. ε- Fe₂O₃ has many promising applications in areas such as high-density magnetic recording media and information storage, millimeter-wave absorption, and magnetic resonance imaging.

Due to the complicated synthetic procedures and a large variety of reaction parameters, fabricating ε-Fe₂O₃ with high-phase purity remains a challenge. To address these obstacles, Livermore researchers have identified critical reaction parameters to improve the phase purity of ε-Fe₂O₃ and tested the effects of all possible reaction parameters through systematic studies. The team used a combination of structural and magnetic characterization techniques to obtain an accurate and reliable phase purity analysis of the ε- Fe₂O₃ phase. Furthermore, researchers were able to identify the optimal conditions that maximize the magnetic coercivity and phase purity of ε-Fe₂O₃, providing insight into the effects of each parameter on the Fe₂O₃ phase-transition pathway.

The research appeared in the Journal of Physical Chemistry C and was highlighted on the issue’s cover. Lead co-author of the paper Jinkyu Han (MSD) says, “We believe that this work will not only provide a pathway toward the rational design of this material but will also enable the fabrication of technologically relevant magnetic architectures.”

Portions of this work were supported by LLNL’s Laboratory Directed Research and Development program (20-LW-039).

[J. Cleron, A.A. Baker, T. Nakotte, A. Troksa, J. Han, Exploring Critical Synthetic Parameters for Nanoscale ε-Fe2O3 and Their Influence on Magnetic Behaviors, The Journal of Physical Chemistry C (2022), doi: 10.1021/acs.jpcc.2c00626.]