Processing and electrical conductivity of lanthanum gallate core-shell heterostructures
authors Gomes, E; Figueiredo, FM; Marques, FMB
nationality International
journal BOLETIN DE LA SOCIEDAD ESPANOLA DE CERAMICA Y VIDRIO
author keywords core-shell; gallate; grain boundary; mixed conductor; impedance spectroscopy
keywords ELECTROCHEMICAL PERMEABILITY; ELECTRONIC CONDUCTIVITY; MECHANICAL ACTIVATION; OXYGEN PERMEATION; OXIDE; CERAMICS
abstract The electrical properties of a lanthanum gallate solid electrolyte were modified by selectively doping the grain boundaries with Fe. This was achieved by sandwiching a La0.95Sr0.05Ga0.90Mg0.10O3-delta (LSGM) dense pellet between LaFeO3 samples. Annealing at 1550 degrees C in air for several hours promoted Fe diffusion into LSGM via the grain boundaries. Scanning electron microscopy and energy-dispersive spectroscopy analyses showed that iron was located at the grain boundary while the grain bulk preserved the LSGM composition. Impedance spectra obtained at low temperature consist of the two usual bulk and grain boundary contributions. A significant increase in total conductivity was observed for the iron-doped samples, the effect being greater for the grain boundary contribution. The total conductivity measured for the iron-containing material revealed a slight decrease with decreasing oxygen partial pressure, suggesting the onset of p-type electronic conduction. Estimates of the p-type electronic conductivity (6) were obtained by fitting the low temperature impedance spectra to a simple equivalent circuit including one parallel electronic branch. The value for sigma(P) in air at 300 degrees C is 3.1x10(-6) S/cm and the activation energy is 75.1 kJ/mol between 300 and 400 degrees C.
publisher SOC ESPANOLA CERAMICA VIDRIO
issn 0366-3175
year published 2006
volume 45
issue 3
beginning page 144
ending page 149
web of science category Materials Science, Ceramics
subject category Materials Science
unique article identifier WOS:000238195900006
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journal analysis (jcr 2017):
journal impact factor 1.049
5 year journal impact factor 0.524
category normalized journal impact factor percentile 53.704
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