The crystal and magnetic structures of orthorhombic ε-Fe 2O3 have been studied by simultaneous Rietveld refinement of X-ray and neutron powder-diffraction data in combination with Mössbauer spectroscopy, as well as magnetization and heat-capacity measurements. It has been found that above 150 K, the ε-Fe2O3 polymorph is a collinear ferrimagnet with magnetic moments directed along the a axis, whereas the magnetic ordering below 80 K is characterized by a square-wave incommensurate structure. The transformation between these two states is a second-order phase transition and involves subtle structural changes mostly affecting the coordination of the tetrahedral and one of the octahedral Fe sites. The temperature dependence of the ε-Fe2O3 magnetic properties is discussed in light of these results. © 2006 American Chemical Society.
Gich, M., Frontera, C., Roig, A., Taboada, E., Molins, E., Rechenberg, H. R., Ardisson, J. D., Macedo, W. A. A., Ritter, C., Hardy, V., Sort, J., Skumryev, V., & Nogués, J. (2006). High- and low-temperature crystal and magnetic structures of ε-Fe <inf>2</inf>O<inf>3</inf> and their correlation to its magnetic properties. Chemistry of Materials, 18, 3889-3897. https://doi.org/10.1021/cm060993l