Dielectric relaxation under pressure in granular dielectrics containing water: Compensation rule for the activation parameters

► We explore for the first time the role of hydrostatic compression to the dielectric relaxation of water-saturated porous dielectrics. ► The activation volume and enthalpy for dielectric relaxation in wetted sandstone are determined experimentally. ► A compensating rule interconnecting the relaxation parameters determined in pressure-temperature experiments; i.e., between the activation volume and the activation enthalpy.