Cationic motion in dehydrated zeolites

ferent ~ entre eux du point de vue coordination et Cnergie potentielle. Le nombre ile sites vides est du meme ordre de grandeur que le nombre de sites occupes. I1 en suit que la migration des cations est corrCl&e. La relaxation die-lectrique est dkcrite par un moment dipolaire par cubo-octahbdre. La grandeur de ce moment dCpend de la compo-sition cationique des cubo-octahkdres. La conductivitk ionique est due au mouvement des cations dans les super-cages. Le mouvement corrClC demande un facteur de corrklation de conductivik5 ionique dans l'iquation de Nernst-Einstein a part du facteur de correlation gkometrique. Abstract.- The exchangeable cations in dehydrated zeolites, types X and Y, are located on several energeti-cally and coordinatively different sites. The number of vacant sites is of the same orde; of magnitude as the number of occupied sites. As a result, the motions of the cations as evidenced by the dielectric relaxation and electrical conductivity, are highly correlated. The dielectric relaxation can be described in terms of a dipole moment per cubooctahedron, the magnitude of which depends on the number of cations in the cubooctahedron. The ionic conduction due to the movement of the cations in the supercages, requires the introdaction of an ionic conducti-vity correlation factor besides the classical geometrical correlation factor in the Nernst-Einstein equation. 1. Introduction.- In dehydrated, synthetic zeo-lites, types X and Y, the exchangeable cations occup