Magnetoelectric Measurements by Two Different Methods of Cobalt Ferrite-Barium Titanate Composites

Abstract

The magnetoelectric coefficient, α = dE/dH, of different compositions of BaTiO3-CoFe2O4 composites was measured by using the dynamic method and also a new method developed in our laboratory which is based on pulsed magnetic fields. The values obtained by both methods are congruent, with the largest magnetoelectric coefficient obtained for the composite with 25% wt. Barium titanate. The magnetoelectric composites were synthesized by the ceramic method. The magnetoestrictive cobalt ferrite powders were synthesized by coprecipitation of cobalt and iron sulfates in acetone and a heat treatment at 1100°C. Commercial piezoelectric barium titanate powders were used of reactive quality (Aldrich, size < 2 μ m). The coupling via elastic deformations of these two phases inside the composite properly polarized, produced a magnetoelectric effect. The starting powders and the composites were characterized by thermal analysis, x-ray diffraction, scanning electron microscopy and particle size distribution using light scattering. Rietveld refinements were also made at the starting powders and composites.