ELECTRICAL AND DIELECTRIC-PROPERTIES OF SILICON SUBSTITUTED COBALT FERRITES

An extensive study of electrical and dielectric properties, on a serie s of Si substituted CoFe2O4 (Co1+xSixFe2-2xO4), has been performed by means of DC electrical resistivity, AC resistivity and dielectric cons tant measurements as a function of temperature. The decrease in DC res istivity with increasing Si4+ concentration is attributed to the Verwe y mechanism between Fe2+ --> Fe3+ and Co2+ --> Co3+. AC resistivity (r ho(AC)), dielectric constant (xi'), dielectric loss (xi '') and loss t angent (tans) show strong temperature dependence at 1 kHz. These resul ts indicate that Si substitution increases the values of xi' and xi '' with increasing temperature, whereas rho(AC) and tan delta decrease w ith increasing temperature. (C) 1998 Elsevier Science B.V. All rights reserved.