Magnetic properties of bulk nanocrystalline cobalt ferrite obtained by high-pressure field assisted sintering

Abstract We present here an investigation aimed at exploring the role of microstructure on magnetic properties nanostructured cobalt ferrite. Bulk, almost fully dense, nanograined ferrites have been obtained starting from nanopowders prepared by a simple, inexpensive, water-based, modified Pechini method. This synthesis yielded largely aggregated, pure single-phase ferrite nanoparticles ca. 35 nm average size, which then densified high-pressure field-assisted sintering. Different sintering conditions (pressure up to 650 MPa and temperature 800 °C) procedures used both as-prepared milled in order obtain materials with spectrum complex microstructures. In all cases, process did not produce any change phase composition. At same time, using high uniaxial pressure combination relatively low temperatures times, allowed for obtaining degree densification while preserving nanometric size crystallites. Moreover, we observed that best are necessarily associated more uniform microstructure, but rather arise delicate balance between moderate aggregation, grain density.