Published online by Cambridge University Press: 03 March 2011
We report studies on the correlation between the microstructure, the magneto-crystalline structure, and the magnetic properties of barium hexaferrite powders. The samples consisted of typical hexagonal plate-like particles with approximate sizes of 80, 180, and 500 nm, obtained by microemulsion, coprecipitation, and solid-state reaction techniques, respectively, and were characterized by x-ray powder diffraction and scanning and transmission electron microscopy. The hyperfine parameters of the hexaferrite powders with different particle size were investigated by Mössbauer spectroscopy. We also measured the magnetization-versus-magnetic field dependence of the submicron powders at high magnetic fields up to 30 T at 4.2 K. Finally, we comment on the surface effects observed because of particle size reduction from micron to nanoscale dimensions.