Mixed conduction induced by grain boundary engineering

abstract

Mixed oxygen-ion electronic conductors were prepared starting from the well-established solid electrolyte La0.95Sr0.05Ga0.90Mg0.10O3-delta (LSGM). The adopted strategy involved selective grain boundary doping with iron to form a grain boundary region with high electronic conductivity. Scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS), impedance spectroscopy in air (around 300 degrees C) and high temperature (700-800 degrees C) ac conductivity measurements as a function of po(2) all suggest that this doping strategy was successful. In fact, on increasing the Fe-dopant level, Fe always concentrated along the grain boundary region (as confirmed by SEM/EDS), the total conductivity increased and each individual impedance arc decreased, in agreement with predictions based on the presence of a parallel pathway for electronic transport. Furthermore, the increase in total conductivity (or) with dopant level showed a positive log a versus log Po-2 dependence, typical of hole conductivity. (c) 2006 Elsevier Ltd. All rights reserved.

keywords

OXYGEN PERMEATION PROPERTIES; ELECTRICAL-PROPERTIES; ELECTRONIC CONDUCTION; COMPOSITE MEMBRANES; LANTHANUM GALLATE; BISMUTH OXIDE; DC TECHNIQUES; PERMEABILITY; TRANSPORT; SYSTEM

subject category

Materials Science

authors

Gomes, E; Figueiredo, FM; Marques, FMB

our authors

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