ORIGINS OF THE DIELECTRIC ABSORPTION IN C ERAMICS

This paper deals with the fundamental aspect of the dielectric absorpt ion of the conducting ceramics and ferroelectric ceramics. We show tha t is possible to evidence dielectric relaxations due to charge carrier s such as electrons and ions, to dipoles reorientations in ferroelectr ics and to interfacial polarization phenomena (grain boundaries) in po lycrystalline compounds. The importance of all these phenomena is disc ussed in relation with their possible interventions in microwave absor ption mechanisms.