Dielectric relaxation studies in the Dy 2O 3CaO system

Abstract

Dielectric relaxation studies have been carried out for Dy 2O 3CaO solid-solid solutions containing four concentrations (3.5, 6.0, 11.0 and 16.0 mol.%) of CaO, at temperatures varying from 93 to 243 K and at selected fixed frequencies. Three types of relaxations (referred as I, II and III) have been identified, the first two of which are Ca 2+-associated and the third La 1+-associated. The identification of the dipole complexes was verified by the identical values of the activation energy E obtained for a typical complex for all four samples, in other words for all the concentrations of CaO in Dy 2O 3: 0.36-0.38 eV for type I, 0.18-0.19 eV for type II and 0.09-0.10 eV for type III. Initially the dipole concentration for each type of Ca-associated complex was found to be proportional to the concentration of CaO added, but a saturation effect was observed for increased CaO concentration, which may be due to increasing order in the nature of formation of domains and microcrystallites. However, the type III complex concentration was found to decrease with increase in CaO.