Dielectric studies of molecular mobility in hydrated zeolites

 
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1993 (EN)
Dielectric studies of molecular mobility in hydrated zeolites (EN)

Daoukaki-Diamanti, D (EN)
Pissis, P (EN)

N/A (EN)

We report on detailed investigations of the dielectric relaxation mechanisms in a Na-13X zeolite by means of the method of thermally-stimulated depolarization currents (TSDC) over a wide range of temperatures, 77-300 K, and water content, 0.020-0.566 w w. Interest is mainly focused on quantitatively characterizing the effects of water on the motion of ions and the reduction of the mobility of water molecules in the confined pore geometry. Five distinct relaxation processes were identified. Three of them were attributed to motions of ions, namely, in the order of increasing temperature, local jumps of ions in the supercages, a Maxwell-Wagner effect and d.c. conductivity. The remaining two processes, present in the samples only for water content higher than a critical one for the completion of the first hydration layer, about 0.30, were ascribed to the reorientation of water molecules in the supercages and the small β-cages, respectively. The reduction of the mobility of water molecules was much stronger in the β-cages than in the supercages. © 1993. (EN)

journalArticle

Spectroscopy (EN)
Maxwell-Wagner effect (EN)
Zeolite supercages (EN)
Hydration (EN)
Porous materials (EN)
dielectric relaxation (EN)
water sorption (EN)
Water molecule mobility (EN)
Zeolites (EN)
Mass transfer (EN)
Dielectric relaxation (EN)
Thermally stimulated depolarization currents (EN)
Hydrated zeolites (EN)
depolarization currents (EN)
Dielectric relaxation spectroscopy (EN)
Dielectric polarization (EN)
conductivity (EN)
Ion motion (EN)
Electric current measurement (EN)
Crystal structure (EN)

Εθνικό Μετσόβιο Πολυτεχνείο (EL)
National Technical University of Athens (EN)

Journal of Physics and Chemistry of Solids (EN)

1993


PERGAMON-ELSEVIER SCIENCE LTD (EN)



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