Abstract
The resistivity of polycrystalline MgZn-ferrites (Mg1.8-xZn0.2Fe1+xO4, 0.79≤x≤1.23) was measured in the temperature range 293-393 K. It showed a maximum value near the stoichiometric composition. Analysis by complex impedance spectroscopy indicated that a potential barrier exists at the grain boundary in stoichiometric composition. According to TEM analysis, the silica concentration at the grain boundaries was higher than the silica concentration of grains. Actually, the resistance at the grain boundaries is one of order magnitude higher than the resistance of grains. This result supports the findings of both complex impedance spectroscopy analysis and TEM.
