Magnetoelectric effect and electrical properties in BTO + Ni0.93Co0.02Cu0.05Fe2O4 particulate composites

Two phase particulate magnetoelectric (ME) composites with compositions (1 - y)BaTiO3 (BTO) + (y)Ni0.93Co0.02Cu0.05Fe2O4 (NiCoCu) (where y = 0.00, 0.15, 0.30, 0.45 and 1.00) were prepared by double sintering ceramic technique. X-ray diffraction patterns confirm the presence of the constituent phases, i.e. ferroelectric and ferrite phase in the composites. Studies on dc resistivity and thermo-emf as a function of temperature were carried out. ac conductivity measurements in the frequency range 100 Hz to 1 MHz, conclude that the conduction is due to small polaron hopping mechanism. The variation of dielectric constant and loss tangent (tan delta) in the frequency range 20 Hz to 1 MHz was also studied. The magnetoelectric voltage coefficient (dE/dH)(H) was measured as a function of intensity of applied magnetic field and mole percent of constituent phases at room temperature. The maximum magnetoelectric, voltage coefficient of 587.75 mu V/cmOe was observed for 70% BaTiO3 + 30% Ni0.93Co0.02Cu0.05Fe2O4 composite at dc magnetic field of 2.1 kOe. The ME response has been explained in terms of resistivity and content of ferroelectric phase. (c) 2007 Elsevier B.V. All rights reserved.