Abstract :
Thermally induced transformations in materials (e.g. melting, decomposition or solid–solid phase changes) alter their dielectric properties and hence their ability to interact with a microwave field. This paper describes a new technique, microwave thermal analysis, where microwaves are used both to heat a material and as a means of detecting thermal transitions. Two approaches are described. The first is based on the changes in the temperature of a material when subjected to a constant microwave power and the second on the microwave power profile obtained when a material is heated in a controlled (linear) manner. Both approaches can provide qualitative and quantitative information on solid state processes. A classification is proposed for the different types of results found for various materials and transitions. The advantages and limitations of studying transitions and reactions using microwave energy are discussed.