Low-frequency dielectric relaxation of Cs+-ions in single-crystals of mica-type layer-silicates

Measurements of the permittivity ?′ and of the dielectric loss ?″ have been made on oriented single-crystals of mica-type layer silicates (vermiculites) in the frequency range 30 Hz–10 MHz. A low-frequency region of dielectric absorption has been observed which has been assigned to the migration of Cs⁺-interlayer cations on free cation sites. In a close relation to this migration we have to assume the reorientation of large electric dipoles—originated in interstitial cation and negative layer charges. Applying the BAUER equation there results an activation enthalpy of diffusion across the lattice of 11.21 $\text{kcal}\text{mol}$. Estimates of an effective dipole moment and of the number of cations contributing to the process agree well with the structural and our experimental data.