Abstract
Lead free Potassium bismuth Titanate K0.5Bi0.5TiO3 (KBT) was prepared by high temperature solid state reaction method in a closed crucible with excess KBT powder around the samples. A room temperature study of XRD confirms, single phase formation with tetragonal structure .Grain and grain boundary conduction is observed from complex impedance spectrum at high temperatures (425°C) by the appearance of two semicircular arcs. The Cole-Cole plots of impedance spectrum consisted of a Circular arc followed by a semicircular spur indicate that the dielectric phenomenon of KBT is due to conductive grain boundaries. The temperature variation of grain resistance and grain boundary resistance is observed with the activation energies. The presence of non-Debye type multiple relaxations has been confirmed by complex modulus analysis. The dielectric data obtained from impedance measurements, indicates broad dielectric peaks around 380°C. The ferroelectric nature confirmed from hysteresis plot. The DC Conductivity results indicate activation energy 0.54 eV below 400°C and 0.85 eV above 400°C. The AC conductivity values and electric modulus values are computed from the impedance data. The activation energies of AC conductivity have observed to decrease with decrease in frequencies.
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