Influence of Processing Condition on Dielectric Properties of K0,5Na0,5NbO3/CoFe2O4 Magnetoelectric Composites

Reference Presenter Authors
08-095 Leonardo Luís Lemes Lemes, L.L.(Universidade Federal de São Carlos); Zabotto, F.L.(Universidade Federal de São Carlos); Garcia, D.(Universidade Federal de São Carlos); Magnetoelectric composites are materials formed by the combination of magnetostrictive and piezoelectric phases, which by means of a mechanical coupling between them makes possible the control of the electric polarization by the application of magnetic fields and the magnetization when applied an electric field. The most well succeeded magnetoelectric composite materials are constituted by lead based piezoelectric matrices (as Pb(ZrxTi1-x)O3, or PZT ferroelectric compounds) which are extremely harmful to the environment and the human health. In order to development of novel lead-free magnetoelectric composites materials, in this work the analysis of the dielectric and magnetoelectric properties of composites based on KNbO3-NaNbO3 (KNN) piezoelectric solid solution as a function of processing conditions are presented. Samples were obtained by solid state mixture of oxides/carbonates and the conventional sintering method was performed at different temperature/soaking time. It was observed that the increment of soaking time result in samples with apparent density optimized (> 95%) and the maintenance of electric resistivity close to 10^9 Ohm / m. On the other hand, when the sintering temperature is increased, it is noticed that the apparent density of samples remains at 95% of the theoretical value, but it is observed a decrease in the electric resistivity which indicates a interdiffusion between the piezoelectric and magnetostrictive phases during the sintering process. Therefore, it is observed that samples sintered at a temperature of 1050 ° C with a soaking time of 10 hours presented better integrity between the constituent phases and consequently better dielectric and magnetoelectric properties.
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