Mixed conduction induced by grain boundary engineering

• Autor(a) principal: Gomes, Eduarda
• Data de Publicação: 2006
• Outros Autores: Figueiredo, F. M., Marques, F. M. B.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/20.500.11960/3055
• topic: Lanthanum gallate; Ionic conductivity

Mixed oxygen-ion electronic conductors were prepared starting from the well-established solid lectrolyte La0.95Sr0.05Ga0.90Mg0.10O3−δ (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 ◦C) and high temperature (700–800 ◦C) ac conductivity measurements as a function of pO2 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 (σ) with dopant level showed a positive log σ versus log pO2 dependence, typical of hole conductivity.