T. Ohgushi et K. Ishimaru, Dielectric properties of dehydrated NaA zeolite, analyses and calculation of dielectric spectra, PHYS CHEM P, 3(15), 2001, pp. 3229-3234
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.