Impedance and modulus spectroscopy studies on Ba0.1Sr0.81La0.06Bi2Nb2O9 ceramic

The modulus and impedance spectroscopy studies on barium strontium lanthanum bismuth niobate (Ba0.1Sr0.81La0.06Bi2Nb2O9, BSLBN) were investigated in the frequency range, 45 Hz-5 MHz and in the temperature duration from room temperature (rt) to 570 degrees C. The dielectric anomaly with a broad peak was observed at 485 degrees C. Simultaneous substitution of Ba2+ and La3+ increases the transition temperature of SrBi2Nb2O9 (SBN) from 392 to 485 degrees C. XRD studies in BSLBN revealed anorthorhombic structure with lattice parameters a=5.5023 angstrom, bla = 1.000 and c = 25.0697 angstrom. Impedance and modulus plots were used as tools to analyze the sample behavior as a function of frequency. Cole-Cole plots showed non-Debye relaxation. DC and AC conductivity measurements were performed on BSLBN. The electric modulus which describes the dielectric relaxation behavior is fitted to the Kohlrausch exponential function. Near the phase transition temperature, a stretched exponential parameter P indicating the degree of distribution of the relaxation time has a small value. (c) 2006 Elsevier B.V. All rights reserved.