ANALYSIS OF EXPERIMENTAL PROBLEMS CONNECTED WITH POLARIZATION CONDUCTIVITY MEASUREMENTS APPLICATION TO ELECTRONIC AND IONIC TRANSPORT

The notion of ''free charge'' and ''bound charge'' is discussed in the field of polarization conductivity. The relation sigma(ac) = sigma(u)psilon + sigma'(omega) is justified. The determination of parameter s of equation sigma'(omega) = A omega(s) is discussed, and an experimental set-up using high impedance electrodes is justified by a simple calculation. The proposed method and therefore the different hypotheses used, have been verified by the study of the polarization conductivity of an electronic semiconductor (pyrocarbon) and of ionic semiconductors (xAg(2)S-yGeS(2), xNa(2)SiO(2)) for given values of x and y. The frequency dependence of s = f(omega) is reported and analysed. This general approach has been tested on a pyrocarbon: which has a high d.c. conductivity.