Direct correlation between ferrite microstructure and electrical resistivity

Variations in the composition and microstructure of Mn-Zn soft ferrites have been directly correlated with spatial variations in electrical resistivity, which were both observed to occur on a length scale of approximately 500 mu m. Tomographic energy dispersive diffraction imaging (TEDDI) was used to determine the nonsystematic change in the lattice parameter across the sample volume (8.48 +/- 0.05 A) at a spatial resolution of 50 mu m. We have used a microprobe contact technique to measure the local electrical resistivity (similar to 35 Omega cm) and density functional theory to model the band structure. The band structure calculations directly utilized the experimentally measured lattice parameters from the TEDDI measurements and were in good agreement with the measured resistivity. The mean band gap shrinkage was found to be 0.02 eV. This value for E-g was found to account well for the observed 10-20 Omega cm resistivity variations. (c) 2007 American Institute of Physics.