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 LaFe0.65Co0.3−xPdxO3 (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 °C. Since no PdO species were detected up to the calcination temperature of 700 °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 °C under 5 vol.% H2 in N2 which was precalcined at 700 °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 °C perovskite can be concluded since no PdO was detected after re-oxidation at 600 °C.