IMPEDANCE AND MODULUS SPECTROSCOPY STUDIES ON LEAD FREE Ba (Tio.96Sno.o2Zr0.02) O3

Abstract

The electrical parameters of the polycrystalline of Ba (Tio.96Sno.o2Zr0.02) 03 in a frequency range of 40Hz to 1MHz at 200-4000C were obtained by the AC complex inpedence spectroscopy technique. A single phase perovskite compound of tetragonal symmetry with space group P4mm was confirmed by X-ray diffraction technique. This study was carried out by means of simultaneous analysis of impedance, modulus and electrical conductivity. Impedence spectroscopy analysis reveal a non-debye type relaxation phenomenon. Grain and grain boundary conduction is observed from complex impedence spectrum by the appearance of two semicircular arcs in the cole-cole (Nyquist) plot at 4000C. this suggests that the grains and grain boundaries are responsible for the conduction mechanisms of the material at high temperature. The bulk resistence of the material decreases with rising temperature similar to a semiconductor which indicates the negative temperature coefficient of resistance (NTCR) character of the sample which makes it for use as highly sensitive thermistor. The bulk and grain boundary resistance, capacitance and relaxation time at 4000C are found to be 44.07, 148.41kΩ, 3.23 x 10-10, 1.17 x 10-8 Farad, and 1.42 x 10-5, 2.55 x 10-3 respectively. AC conductivity of the ceramics increases as a function of frequency due to relaxation phenomenon arisen due to mobile charge carriers. The nature of frequency dependence of AC conductivity confirms the Jonscher’s power law.