Non-Arrhenius viscosity related to short-time ion dynamics in a fragile molten salt.
The equation T x sigmaDC(T) = alpha x exp[--(E*/kappa(B)T)--gamma x exp(E*/kappa(B)T)] has been used to understand the non-Arrhenius behaviour of the DC conductivity in supercooled glass-forming melts. Here, alpha, gamma and E* are parameters, E* denoting the activation energy for an elementary displacive step. Unlike the empirical VTF relation, our equation provides a link between the long-time and the short-time ion dynamics as observed in broad-band conductivity spectra. Surprisingly, the same equation with the same value of E* but different gamma successfully describes the fluidity (inverse viscosity) of a fragile glass-forming melt. This opens up the possibility of relating non-Arrhenius viscosities to short-time properties, which is in agreement with recent experimental and computer-simulation results.
Westfälische Wilhelms-Universität Münster, Institut für Physikalische Chemie and Sonderforschungsbereich 458, Corrensstrasse 30, D-48149 Münster, Germany.
Prabhakar
P
Singh
Radha D
RD
Banhatti
Klaus
K
Funke