Bulk and grain boundary conductivity of Ca0.97Ti1-xFexO3-delta materials
authors Chinarro, E; Jurado, JR; Figueiredo, FM; Frade, JR
nationality International
journal SOLID STATE IONICS
author keywords calcium titanate; impedance spectroscopy; grain boundaries
keywords STRONTIUM-TITANATE CERAMICS; ACCEPTOR-DOPED TITANATES; CALCIUM TITANATE; ELECTRICAL-CONDUCTIVITY; DEFECT STRUCTURE; IMPEDANCE SPECTROSCOPY; OXYGEN PERMEATION; LAYER; SR0.97TI1-XFEXO3-DELTA; CHEMISTRY
abstract Polycrystalline Ca0.97Ti1-xFexO3-delta samples with x = 0, 0.01, 0.035, 0.07 and 0.15 were prepared by a conventional ceramic route and characterised by impedance spectroscopy at different temperatures in air. Spectra obtained for samples with low iron contents (x < 0.05) clearly show two separated bulk and grain boundary contributions, which were used to determine the corresponding conductivities. Though the bulk conductivity of those samples increases slightly with additions of Fe, the true grain boundary conductivity was found nearly independent of the content of Fe, except for effects of microstructure, such as differences in grain size. The grain boundary layer thickness was also estimated. The impedance spectra obtained for samples with Fe contents of 7% or higher show a single contribution attributed to the bulk suggesting a very low grain boundary resistance, and thus revealing a major change in grain boundary behaviour relative to samples with small Fe contents. (C) 2003 Elsevier Science B.V. All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 0167-2738
year published 2003
volume 160
issue 1-2
beginning page 161
ending page 168
digital object identifier (doi) 10.1016/S0167-2738(03)00151-6
web of science category Chemistry, Physical; Physics, Condensed Matter
subject category Chemistry; Physics
unique article identifier WOS:000183883000019
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