Dielectric properties of dehydrated NaA zeolite, analyses and calculation of dielectric spectra

Dielectric spectra (epsilon', epsilon" and tan delta) of dehydrated NaA zeo lite were measured in the temperature range 330-510 K and analyzed in detai l to determine the characteristic values (epsilon (s), epsilon (infinity), beta and peak frequency) of the dielectric relaxations. Two relaxations cau sed by Na+ ion as an exchangeable cation were measured in the spectra and t he relaxations on the lower and higher frequency sides had activation energ ies of 60 and 49 kJ mol(-1), respectively. By using the optimum characteris tic values determined, the spectra of epsilon', epsilon" and tan delta at e ach temperature were calculated, and each calculated spectrum was in good a greement with the measured spectrum. The temperature dependences of all cha racteristic values were determined and hence it was possible to calculate t he spectra at various temperatures. The characteristic values were also est imated by plotting the measured data on the Cole-Cole plane and separating the Cole-Cole curve separated into three parts including two circular arcs. The characteristic values estimated by this method were not in agreement w ith those determined by the former method. The limitations of the latter me thod are discussed.