abstract
Complex impedance spectroscopy (CIS) technique has been utilized to investigate the intra- and intergranular contributions to the impedance in pristine and wolframium (tungsten, W) -substituted strontium bismuth tantalate [SrBi2(Ta1-xWx)(2)O-9 (SBTW); x=0.0, 0.025, 0.05, 0.075, 0.1 and 0.2] ceramics as a function of temperature and frequency. CIS studies reveal that the electrical relaxation process was temperature dependent and non-Debye type. The temperature dependence of the relaxation time was found to obey the Arrhenius law. DC conductivity of the studied samples obtained from the CIS data decreased for W content upto x=0.05, followed by a subsequent increase with x > 0.05. Electrical conductivity data including the typical values of the activation energies at high temperature indicated that the conductivity in the studied ceramics was essentially due to the contribution of doubly ionized oxygen vacancies to the conduction process. (C) 2012 Elsevier B.V. All rights reserved.
keywords
MODULUS SPECTROSCOPY; COMPLEX IMPEDANCE; SRBI2TA2O9; RELAXATION; TRANSPORT; GLASSES; OXIDES
subject category
Physics
authors
Coondoo, I; Panwar, N; Tomar, A; Jha, AK; Agarwal, SK
our authors
Indrani Coondoo
Junior Researcher
Neeraj Panwar
Post-doc Fellowshipacknowledgements
One of the authors (I.C.) would like to thank Portuguese Foundation for Science and Technology (FCT) for the Postdoctoral Grant through no. SFRH/BPD/81032/2011. The author S.K.A. would like to thank the Council of Scientific and Industrial Research (CSIR), India for providing the financial grants under the Emeritus Scientist scheme.