Electrical properties of K0.5Bi0.5TiO3

Lead-free potassium bismuth titanate K0.5Bi0.5TiO3 (KBT) is prepared by conventional double sintering method in a closed crucible with excess KBT powder around the samples. The Phase formation was confirmed by XRD-studies and the lattice constants were calculated. The dielectric measurements in the temperature range 30-600 degrees C at set frequencies (10 KHz to I MHz) indicate broad dielectric peaks around 380 degrees C. The pyroelectric measurements were carried out on poled samples in the temperature range of 30-500 degrees C. The pyroelectric measurements confirm the ferroelectric nature of the samples. The impedance measurements were carried out in the frequency range of 1 KHz to 1 MHz as a function of temperature. The relaxation times were calculated from the frequency explicit plots of imaginary part of impedance (Z '') and the Arrhenius plots of the relaxation times indicate activation energy of 1.08 eV and 0.56 eV below and above 385 degrees C, respectively. The dc conductivity results indicate activation energy 0.54 eV below 400 degrees C and 0.85 eV above 400 degrees C. The ac conductivity values computed from the impedance data follow the universal power law. (C) 2007 Elsevier B.V. All rights reserved.