Calorimetry through dielectric measurements: A powerful investigation technique for condensed matter

Froehlich entropy (FE) is the entropy variation of a material under an applied electric field. Under suitable hypotheses, this quantity can be calculated from the real part of the permittivity as a function of temperature. A straightforward physical interpretation correlates FE to the state-of-order of the considered physical system, when the analysis of FE gives several information about the evolution in temperature of the explored compound, especially of its phase transition features. Here we present a comprehensive review of the physical systems (dipolar liquids and nematicons, organic molecular crystals, metallic nanoparticles, inorganic disordered ferroelectrics, etc.) where this method has been used with the aim of evaluating their state-of-order on temperature. The variety of compounds where this approach was applied indicates that the estimation of the FE is a reliable tool to accomplish studies on the state-of-order of different classes of materials. Therefore, FE estimation can be considered a fruitful and trustworthy investigation technique, which can be used as an alternative to standard experimental approaches.