Hollow iron submicron spheres with strong ferromagnetism

Hollow iron submicron spheres with high saturation magnetization at room temperature were successfully developed for the first time. By means of spray pyrolysis, α -Fe2O3 hollow spheres with the diameter ranging from 0.5 µm to 2.5 µm and an average shell thickness of approximately 20 nm could be obtained in large scale. In subsequent reductive annealing under dilute hydrogen atmosphere, as-synthesized α -Fe2O3 can be transformed into Fe3O4,...