Structural, dielectric, thermal and electron magnetic resonance studies of magnetic porous glasses filled with ferroelectrics

Magnetic, dielectric and thermal properties of multiferroic nanoparticles were synthesized with a novel magnetic porous glass-based method. We report the properties of empty magnetic porous glasses and ones filled with NaNO2 or KNO3 ferroelectrics. It was shown that the ferroelectric nanocomposites obtained on the basis of porous glasses exhibit both ferroelectric and ferromagnetic properties. The dielectric permittivity and the ac conductivity were discussed as a function of frequency and temperature. For all obtained multiferroic nanocomposites the dielectric results show a ferroelectric-like behavior. The specific heat was measured using the DSC method and the anomaly of the ferroelectric phase transitions was indicated. We report on the magnetic properties of multiferroic nanocomposites investigated by EMR at two frequencies (X, S band). Both the temperature and the frequency dependencies of the narrow and broad resonance lines fulfilled a condition for the superparamagnetic behavior of porous glasses with ferroelectric particles inside. Finally, we were able to measure the ferroelectric polarization for magnetic porous glasses filled with NaNO2 ferroelectrics. The particle-size dependent magnetic, dielectric and thermal properties of the obtained multiferroics nanocomposites were studied.