Direct correlation between ferrite microstructure and electrical resistivity

Abstract

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 μm. 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 Å) at a spatial resolution of 50 μm. We have used a microprobe contact technique to measure the local electrical resistivity (∼35 Ω 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 Eg was found to account well for the observed 10−20 Ω cm resistivity variations.

Combined Effect of Microstructure, Surface Energy, and Adhesion Force on the Friction of PVA/Ferrite Spinel Nanocomposites

“…The properties of ferrites are influenced by the method of synthesis, the composition, the microstructure features, and the distribution of cations in the tetrahedral and octahedral sites in the lattice of the ferrite [8][9][10]. The distribution of equilibrium between the spinel structure cations depends on ionic, electronic, and polarizing effects [11][12][13][14].…”

X-ray colour imaging

“…The accuracy of the lattice parameters from the TOPAS refinement is lower than that expected from traditional powder measurements, occurring in this case to the second decimal place; however, detector efficiency improvements will alleviate this problem. The intensity variations due to local structural differences can be treated qualitatively to give information on grain clustering (Cernik et al 2007). However, the integrated intensities are not sufficiently reliable to enable structure determination or full Rietveld refinement.…”

On the localized impedance spectroscopic characterization of grain boundaries: General aspects and experiments on undoped SrTiO3

“…[5][6][7][8][9][10][11][12] In materials with the grain boundary resistance being of the same order of magnitude as the bulk resistance impedance spectroscopy can again help identify different contributions of the total resistance measured between two microelectrodes. Therefore, recent papers also dealt with the impedance spectroscopic analysis of grain boundaries in Fe-doped SrTiO 3 or Mn-Zn-ferrites using microelectrodes.…”