AC response of Bimodified Pb0.92La0.08(Zr0.65Ti0.35)(0.98)O-3 ceramics

摘要

Polycrystalline electroceramics have been prepared by varying modifier to former (Bi/La) ratios (z/1 - z) according to the complex formula Pb-0.92[ La(1-z)Biz](0.08)[Zr0.65Ti0.35](0.98)O-3 (PLBZT), where z = 0.0, 0.3, 0.6. The electrical properties of PLBZT compounds were studied using the ac impedance spectroscopy technique over a wide range of temperature ( 30 - 500 degrees C) in the frequency range of 100 Hz-1 MHz. Nyquist plots recorded at different temperatures show a decrease in the bulk resistance (Rb) with rise in temperature for PLZT material (z = 0.0) i.e., NTCR behavior like semiconductors. The Nyquist plots also indicates that the bulk resistance of the material has been observed to be concentration dependent and decreased in two order of magnitude with higher Bi-addition in PLZT matrix. Bismuth (Bi) substitution at the lanthanum (La) position not only resulted in lowering of the electrical resistance with its higher concentration but also has changed the NTCR behavior of PLZT (z = 0.0) to PTCR (positive temperature coefficient of resistance) for PLBZT. Electrical property studied by complex impedance spectroscopic method also indicates the evidence of (i) single electrical relaxation attributed to the presence of bulk contribution to the electrical properties, (ii) presence of temperature dependent electrical relaxation phenomenon and (i) diminution in the barrier to the mobility of charge carrier on Bi-substitution.