Oxygen permeability of LaGa0.65Ni0.20Mg0.15O3-δ ceramics: Effect of synthesis method

• Autor(a) principal: Shaula, A.L.
• Data de Publicação: 2003
• Outros Autores: Viskup, A.P., Kharton, V.V., Logvinovich, D.I., Naumovich, E.N., Frade, J.R., 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/10773/21982
• topic: Ceramics; Chemical synthesis; Ionic conductivity; Oxides; Surface properties; Lanthanum compounds; Microstructure; Oxygen permeable membranes; Synthesis (chemical); Thermal expansion; Oxygen permeability; Ceramic materials

Oxygen ionic transport in dense LaGa0.65Ni0.20Mg0.15O3-δ membranes, prepared by the standard ceramic synthesis technique and via glycine-nitrate process (GNP), was studied using measurements of the total conductivity, oxygen permeation and faradaic efficiency (FE). At 1223 K oxygen transfer through LaGa0.65Ni0.20Mg0.15O3-δ ceramics is mainly determined by the bulk ambipolar conductivity, while decreasing temperature leads to a greater role of the surface exchange rate. In spite of moderate difference in the ceramic microstructures, the surface exchange limitations are considerably higher for the membranes prepared by the standard ceramic route compared to GNP-synthesized material. Thermal expansion and partial ionic and electronic conductivities were found essentially independent of the synthesis method. The level of oxygen ionic conduction in LaGa0.65Ni0.20Mg0.15O3-δ, characterized by the activation energy of about 150 kJ/mol and ion transference numbers in the range 1 × 10-3-5 × 10-2 at 973-1223 K, is higher than that in La(Ga,Ni)O3-δ perovskites and comparable to La2NiO4-based phases.