International audienceAccurate conductivity measurements as a function of hydrostatic pressure (1 – 5000 bars) and temperature (20 – 150 °C) have been performed on a cationic inorganic glass and a cationic conducting polymer.In both cases, the conductivity decreases with increasing pressure and the variation of Inσ at constant temperature as a function of pressure gives straight lines with slopes which allow an “activation volume”, ΔV*, to be obtained by the relationship (∂lnσ/∂P)T=− (ΔV*/RT). In the case of silver metaphosphate glass, studied below its glass transition temperature, the activation volume (5 cm3⋅mol−1) is temperature independent and equal to the molar volume of the silver cation. Since the transport mechanism implies a free ...