Crystal Research and Technology
Cryst. Res. Technol. 42, 699 (2007) - Abstract -

Impedance spectroscopy of Na and Nd doped strontium bismuth titanate

R. Rizwana, T. Radha Krishna, A. R. James*, and P. Sarah

Material Research Lab., CVR College of Engg., Mangalpalli, Ibrahimpatan, R R District-501 510, A.P, India
*Defence Metallurgical Research Lab., Kanchanbagh, Hyderabad-500 058, A.P, India

Keywords complex impedance spectroscopy, grainboundaries, equivalent circuit, ac conductivity, hopping transport
PACS 73.50.Gr, 78.55.Qr, 77.22.Jp, 77.22.Gm, 76.60.Es
DOI 10.1002/crat.200610891

Sr0.2Na0.4Nd0.4Bi4Ti4O15 is prepared by Sol-Gel route using the modified polymeric precursor method based on the Pechini process and its electrical properties are investigated by Complex Impedance Spectroscopy (CIS). Results are presented in two ways, complex plane plots (real versus imaginary) and spectroscopic plots (real and imaginary against frequency). CIS has provided convincing evidence for the existence of both grain (bulk) and grain-boundary effects that were separated in the frequency domain of the impedance spectrum. Experimental data are fitted to two parallel RC equivalent circuits in series. The values of resistance and capacitance of bulk and grain boundary contributions are also calculated. Relaxation times are calculated for both grains and grainboundaries. Conduction and charge carrier behaviors are studied from frequency and temperature dependence of ac conductivity. The ac conductivity follows a two-power law behavior at different temperatures with frequency exponents s1 and s2.




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