Response of dielectric behaviour in piezoelectric and magnetostrictive composites

The magnetoelectric composites consisting of ferrite and ferroelectric phases viz. (y)Mn_0.45Ni_0.05Zn_0.50Fe₂O₄₊ (1™y)BaZr_0.52Ti_0.48O₃ in which y varies from 0.20-0.80 mol% were prepared by standard solid state reaction method. X-ray analysis of these composites confirms the presence of both the phases, i.e. ferroelectric and ferrite in the composites. Detailed studies of dielectric constant, loss tangent, and ac conductivity, as a function of frequency (20 Hz - 10 MHz) were studied. The dielectric constant decreases steeply at lower frequencies and remains constant at higher frequencies, indicating dielectric dispersion. This may be attributed to polarization due to changes in the valence states of cations and space charge polarization. Results of ac conductivity show that conduction occurs by hopping of charge carriers. The static magnetoelectric voltage coefficient was measured as a function of applied dc magnetic field. It decreases with increasing dc magnetic field. These composites may be useful as transducer, magnetic sensors, filter, etc.