Structural and impedance spectroscopy study of Samarium modified Barium Zirconium Titanate ceramic prepared by mechanochemical route

Abstract

Samarium modified Barium Zirconium Titanate (BZT) ceramics with general formula [Ba1-xSm2x/3](Zr0.05Ti0.95O3) [x = 0, 0.01, 0.02, 0.03 and 0.04] have been prepared by high energy ball milling. The Rietveld refinement of BaZr0.05Ti0.95O3 (BZT) shows a single phase tetragonal symmetry with space group P4mmm and TEM micrograph shows that the crystalline size is in the submicron range. X-ray diffraction (XRD) patterns confirm that no phase change occurs with the addition of Samarium in BZT upto x <= 0.03 and a small pyrochlore phase exists at x = 0.04. The complex impedance (Nyquist) plots display a single semicircle highlighting the influence of grain resistance on the electrical behavior. Negative temperature coefficient of resistance behavior is observed in all compositions. The activation energy calculated from Z '' and DC conductivity confirms that the oxygen vacancies play an important role in the conduction mechanism. (C) 2014 Elsevier B.V. All rights reserved.