Meta-stability and microstructure of the LaFe0.65Co0.3Pd0.05O3 perovskite compound prepared by a modified citrate route

In this paper we report the synthesis and analysis of lanthanum based perovskites substituted with Pd by employing a modified citrate route. Crystallization and phase sequences of the LaFe0.65Co0.3PdxO3 (x = 0, 0.05) perovskite(s) are analyzed by means of powder XRD and Rietveld refinement. Regarding the crystal phase development at the LaFe0.65Co0.3Pd0.05O3 perovskite a meta-stable structure can be postulated at temperatures up to 700 degrees C. Since no PdO species were detected up to the calcination temperature of 700 degrees C we can conclude that Palladium ions are successfully incorporated into the B-site of the crystal structure of the perovskite. Reduction of the LaFe0.65Co0.3Pd0.05O3 perovskite at 600 degrees C under 5 vol.% H-2 in N-2 which was precalcined at 700 degrees C causes segregation of palladium to form metallic particles with sizes between 10 and 15 nm. Reversible Pd ions reincorporation into the crystal lattice of the LaFe0.65Co0.3Pd0.05O3-700 degrees C perovskite can be concluded since no PdO was detected after re-oxidation at 600 degrees C. (c) 2008 Elsevier Ltd. All rights reserved.