On the Dispersion of Resistivity and Dielectric Constant of Some Semiconductors at Audiofrequencies

Semiconducting ${\mathrm{Ni}}_{0.4}$ ${\mathrm{Zn}}_{0.6}$ ${\mathrm{Fe}}_2$ ${\mathrm{O}}_4$, prepared in different ways, has been investigated. It appeared that the ac resistivity and the apparent dielectric constant of the material show a dispersion which can be explained satisfactorily with the help of a simple model of the solid: there should be well-conducting grains separated by layers of lower conductivity. Dispersion formulas are given. There is good agreement between experiment and theory.