Dielectric and Magnetoelectric Characterization of CoFe_(2)O_(4)/Sr_(0.5)Ba_(0.5)Nb_(2)O_(6) Composites

摘要

Magnetoelectric composites were created through incorporating dispersed CoFe_(2)O_(4) ferromagnetic grains into a Sr_(0.5)Ba_(0.5)Nb_(2)O_(6) relaxor ferroelectric matrix. The two phases are chemically compatible and coexist in the dense, sintered composites. Unlike other relaxors, the Sr_(0.5)Ba_(0.5)Nb_(2)O_(6)-containing composites can be electrically poled. The apparent dielectric constant is enhanced by the conductivity in the ferrite phase and the space charge at the phase interface. A significant magnetoelectric effect was observed in all compositions investigated, with a maximum dE/dH value of 24.8 mV/cm/Oe obtained for 0.4CoFe_(2)O_(4)/0.6Sr_(0.5)Ba_(0.5)Nb_(2)O_(6), which is much greater than that of magnetoelectric compounds and solid solutions. These results demonstrate that the Pb-free (Sr,Ba)Nb_(2)O_(6) relaxor can be advantageously used as the matrix for ferromagnetic/ferroelectric composites in the future development of magnetoelectric materials.