• Clennell, Michael
• Josh, Matthew

Abstract

Limitation of the macroscopic approach to molecular behavior or microscopic mechanisms of clay mineral polarization is not well understood and is still controversial, for example, no consensus has been reached on the types of polarization and their frequency ranges among researchers. The aim of the present study was to quantify the frequency-dependence of the complex permittivity of K+- smectite partially or fully saturated with water and to determine the relaxation frequency of the K+- smectite for pore size of ~ 1nm(smectite matrix with basal spacing of 1.6 nm) with water contents that varied from 20 to 100 wt.% using molecular dynamics (MD) simulations. The simulation results of the dielectric spectra evidenced an unchanged polarization mechanism occurring within the K+- smectite with nano-pore size, characterized by a water content dependent dielectric strength, but water content independent characteristic frequency of ~ 30 GHz. The permittivity relaxation was found to be non-Debye type relaxation. Instead, a circular arc locus was a good representation of the simulated data. The deviation from pure Debye behavior reduced and the dielectric permittivity became much more significant as water content increases. The results presented here identified the dielectric relaxation due to the orientational correlation of the water molecules near the K+- smectite surface and gave support to the idea that the relaxation frequency reflects the dimension of pores. This work constitutes a novel contribution to the dielectric spectra of overall wet K+-smectite by extending the dielectric behavior of this system to a microscopic level description.

Topics

• impedance spectroscopy
• pore
• mineral
• surface
• simulation
• molecular dynamics
• strength
• dielectric strength