Characterization of perovskite powders for cathode and oxygen membranes made by different synthesis routes

Strontium lanthanum manganite (LSM) and lanthanum ferrite (LSF) perovskite cathode and oxygen membrane materials were synthesized using different techniques: spray pyrolysis, a modified citrate route, oxalate and carbonate co-precipitations. The use of Ca, a cheaper substituent on the A-site, was explored along to the substitution of La by Pr. The differently sourced powders were characterized by TG/DTA, XRD, ICP, TEM, XPS, PSD and BET. The co-precipitation of La, Ca and Fe was also possible using the cyanide route. This complexation method allowed the precipitation of a crystalline phase as evidenced by XRD. Among all methods, the cyanide and carbonate co-precipitation allowed the lowest perovskite phase transformation for LSF and LCF, followed by the nitrate (i.e. 'spray pyrolysis'). These phase transformation differences affected much the particle size distribution and the surface areas of these materials, the carbonate and the cyanide routes giving rise to very fine powders in the nm range. XPS and TEM analyses indicated uneven composition distributions. These different powder characteristics are expected to affect the catalytic and electrochemical properties of these materials. (c) 2005 Elsevier Ltd. All rights reserved.