Communication: Inflection in the pressure dependent conductivity of the protic ionic liquid C8HIM NTf2

Temperature and pressure dependent broadband dielectric measurements were performed on the protic ionic liquid C8HIM NTf2 over a frequency range from 0.1 Hz to 1 MHz. The temperature dependence of the inverse dc-conductivity exhibits the super-Arrhenius like behavior typical for glass forming materials. However, in the pressure dependence both slower and faster than exponential developments occur, resulting in an inflection in the corresponding curves. The experimental data was successfully fitted with a model incorporating both features. While similar transitions have been observed in the pressure dependent viscosity or structural relaxation times, this is the first time such a behavior is reported in the conductivity.