Anomalous electrical conductivity behavior at elevated pressure in the protic ionic liquid procainamide hydrochloride.
Using broadband dielectric spectroscopy, we investigated the effect of hydrostatic pressure on the conductivity relaxation time τ{σ} of the supercooled protic ionic liquid, procainamide hydrochloride, a common pharmaceutical. The pressure dependence of τ{σ} exhibited anomalous behavior in the vicinity of the glass transition T{g}, manifested by abrupt changes in activation volume. This peculiar behavior, paralleling the change in temperature dependence of τ{σ} near T{g}, is a manifestation of the decoupling between electrical conductivity and structural relaxation. Although the latter effectively ceases in the glassy state, free ions retain their mobility but with a reduced sensitivity to thermodynamic changes. This is the first observation of decoupling of ion migration from structural relaxation in a glassy conductor by isothermal densification.
Institute of Physics, Silesian University, ul. Uniwersytecka 4, 40-007 Katowice, Poland.
Z
Z
Wojnarowska
C M
CM
Roland
A
A
Swiety-Pospiech
K
K
Grzybowska
M
M
Paluch