Dielectric and magnetic properties of some gadolinium silica nanoceramics

Some nanostructure gadolinium silica glass-ceramics were obtained undergoing a sol gel method and a heat-treatment at 1000 degrees C about two hours. The magnetic and dielectric properties of these samples were studied. The magnetic properties were evidenced performing susceptibility measurements in the 80-300K temperature range. A Curie-Weiss behavior has acquired. The values estimated for paramagnetic Curie temperature being small and positive suggest the presence of weak ferromagnetic interactions between Gd3+ ions. The dielectric properties were evaluated from dielectric permittivity (epsilon(r)) and dielectric loss (tan delta) measurements at the frequency 1 kHz, 10 kHz and 100 kHz, in the 25-225 degrees C temperature range and dielectric dispersion at room temperature for 79.5 kHz - 1GHz frequency area. The dielectric properties suggest that the main polarization mechanism corresponds to interfacial polarization, characteristic for polycrystalline-structured dielectrics. The polycrystalline structure of the samples is due to the polymorphous transformations of the nanostructure silica crystallites in the presence of gadolinium oxide. They were highlighted by SEM micrographs.