(Keynote) The Piezoelectric Effect and Ionic Liquids

We have studied the response of room temperature ionic liquids to surface charge and had found the establishment of a free charge density gradient, ρ f , in these materials that persists for ca . 50 μm ( e -1 depth). We have also applied mechanical force to room temperature ionic liquids with the resulting development of a potential across the ionic liquid when contained in a vessel. These two effects are manifestations the converse and direct piezoelectric effects, respectively. For the converse piezoelectric effect, the induced gradient is seen to be ca . 100 μC/cm 3 /μm and for the direct piezoelectric effect, the relationship between force applied and potential developed is ca . 16 mV/N. We will discuss the observation of the direct piezoelectric effect in the liquid phase and its possible utility.