Configurational Changes

Abstract

Anomalous variations of thermodynamic properties are observed when the configuration of a phase changes. A few examples will first show the diversity of these changes and their influence on the heat capacity. The most dramatic kind of configurational effects, phase transitions, will then be discussed as continuous and first-order transformations. From the critical point of fluids, we will introduce critical exponents and order parameters and illustrate their general usefulness by means of Landau theory for crystal-crystal transitions. We will investigate kinetic transitions, through which systems lose internal equilibrium and acquire a nonzero entropy at 0 K. The most important example will be that of the glass transition, in the light of which a few order-disorder transitions in crystals will be finally discussed.