Phase transitions in molecular crystals as an example of coupled systems studies

Abstract

Molecular crystals exhibit phase transitions under various temperature, pressure and concentration conditions. Thermodynamic quantities such as the specific heat, thermal expansion and isothermal compressibility show critical behaviour near the transition point. This critical behaviour can be observed experimentally and it can also be predicted using various theoretical models. Phase transitions in molecular crystals as an example of coupled studies are reviewed here. Thermodynamic, ferroelectric, ferromagnetic systems and composite materials which show phase transitions, are all included. Phase diagrams of those materials are also the subject of this study. Various theoretical models and the analysis of the experimental data from the literature for some molecular crystals as coupled systems close to the phase transitions, are reviewed including those developed by our group. Some of those analyses are illustrated for different coupled systems exhibiting phase transitions. For all these materials studied, a wide range of references are included, which may lead the readers to study the other aspects of the coupled systems near the phase transitions, either using the same kind of analysis methods given here or developing some others by using several theoretical models.