Electrical and magnetic properties of coprecipited Ba-hexaferrites with addition of SiO2

Abstract

Preliminary results on the effects of magnetic, electrical and structural characteristics of BaFe12O19, with addition of SiO2, prepared by the chemical coprecipitation method are reported. Several firing temperatures were used to investigate the admixture of SiO2 in the samples. Experimental data of electrical conductivity were obtained by ac measurements. Results are presented in terms of thermal and frequency dependent conductivity, sigma(omega). Universal sigma(0) + A omega s-type behavior is observed for log sigma(omega) vs logf

while log sigma(omega) against 1000,/T, at fixed frequencies, exhibit deviation of an Arrhenius behavior as frequency increases. Generally speaking, curves of ac measurements follow the jump relaxation model. The addition of SiO2 modifies slightly the observed conductivity. Saturation magnetization and coercitivity as a function of the thermal treatment of the samples, in the interval 950 degrees C-1220 degrees C, are also reported.