Foundations of thermo-dielectrical analysis

Abstract

The dielectric susceptibility of dehydrated homoionic Zeolites was calculated by using a cation hopping model consisting of classical jumps over a barrier. The calculation method was based on determination of the response function of the homoionic dehydrated zeolite under transient excitation. The dielectric susceptibility expression obtained was compared with experimental dielectric spectra at different temperatures and the activation energy for cationic diffusion in the zeolites tested was also calculated. The results were within the range of values reported for cationic migration in the solid state. Further, there is a clear difference between the activation energies of Na and Ca diffusion and this fact forms a quantitative basis for the explanation of the thermodielectric thermograms of homoionic sodium and calcium zeolites and promote the understanding of the role of cationic polarization and cationic migration in thermodielectric analysis.The study of the role of cationic polarization in thermodielectric analysis by using the dispersion spectrum of zeolites measured with a dielectric spectrometer developed in our laboratory [1] was discussed in the first paper of the present series. The approach used was essentially qualitative and the aim of the present report is to give a quantitative discussion of the role of cationic migration in zeolite polarization phenomena. Zeolite was selected as model material because of the presence in its thermodielectric thermograms of the most important polarization effects recorded by this method [3][4][5][6][7].Therefore, the object of the present paper is the calculation of the dielectric susceptibility of dehydrated homoionic zeolites based on a model of cation hopping polarization [8]. Further, we compare the experimental John W'dey & Sons, Limite~ Chichester ~ Kiad6, Budap~