Formation of the hard-magnetic epsilon iron oxide phase from akaganéite nanoparticles
Elongated akaganéite (<i>β</i>-FeOOH) nanoparticles were prepared by a forced hydrolysis route using FeCl<sub>3</sub><b>·</b>6H<sub>2</sub>O employing various urea concentrations.<i>β</i>-FeOOH nanoparticles stabilized within the SiO<sub>2</sub>matrix were annealed at different temperatures, ranging from 500 °C to 1300 °C. It was observed that<i>β</i>-FeOOH underwent a temperature-induced conversion to<i>γ</i>-Fe<sub>2</sub>O<sub>3</sub>and subsequently to<i>ϵ</i>-Fe<sub>2</sub>O<sub>3</sub>. Due to the<i>ϵ</i>-Fe<sub>2</sub>O<sub>3</sub>phase formation, the coercivity rapidly increased to 16 kOe for samples annealed at 900 °C and reached values up to 21.5 kOe when annealed at 1200 °C. At a higher temperature of 1300 °C, the<i>ϵ</i>-Fe<sub>2</sub>O<sub>3</sub>phase transforms mainly into the<i>α</i>-Fe<sub>2</sub>O<sub>3</sub>phase, which causes the coercivity to rapidly drop to negligible values.
Authors
- Senoy Thomas (ORCID: https://orcid.org/0000-0001-9072-3584)
- Aladin Ullrich (ORCID: https://orcid.org/0000-0003-0486-0975)
- M. Albrecht (ORCID: https://orcid.org/0000-0002-0795-8487)
- Navya Joseph
- Sreerag Gopi (ORCID: https://orcid.org/0000-0002-4476-6433)
Institutions
- University of Augsburg (DE)
- Cochin University of Science and Technology (IN)
Publication Details
- Journal
- Nanotechnology
- Published
- 2024-10-17
- DOI
- https://doi.org/10.1088/1361-6528/ad844f
- Citations
- 1
- Primary Topic
- Iron oxide chemistry and applications
- Type
- article
- Field-Weighted Citation Impact
- 0.10
Funders
- Kerala State Council for Science, Technology and Environment