The effect of transformations induced by annealing at different temperatures (450<Ta<1000 °C) on the structure and magnetic properties of acicular α-Fe2O3particles (major axis: 330±50 nm; minor axis: 70±10 nm) have been investigated by X-ray diffraction, TEM, SEM and magnetization measurements. The particles were prepared by hydrolysis and polymerization in an aqueous solution of FeCl3. In the as-prepared sample, particles are constituted by small units (3-5 nm) separated by a less dense interlayer, while keeping the same crystallographic orientation. With increasing Ta, the sample microstructure evolves towards a collapse of the small units and then to a coalescence of particles. Coherently, the spin reorientation Morin temperature TMincreases with Ta, the highest value (TM= 259 K) being comparable to that of the bulk sample.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
Suber, L., Fiorani, D., Imperatori, P., Foglia, S., Montone, A., & Zysler, R. (1999). Effects of thermal treatments on structural and magnetic properties of acicular α-Fe. Nanostructured Materials, 11(6), 797 - 803. https://doi.org/10.1016/S0965-9773(99)00369-4