Catalytic and physico-chemical properties of La1−xSrxCoO3 perovskites

Effect of structural disorder on the catalytic activity of mixed La−Sr−Co−Fr−O perovskites

“…Probably, strains accumulated in the transient metastable sample due to a cooperative effect of the iron impurity are partly relaxed by the generation of incoherent grain boundaries or other extended defects. As a result, a high density of surface defect centers is ensured; its importance for CO oxidation has already been shown [7]. Further attempts to elucidate details of the coordination of cations in the transient sample using IR spectroscopy of the lattice modes failed due t~ a high density of free charge carriers (electrons [8]), since high absorbance made registration of spectra impossible.…”

“…This trend is not appreciably changed by the action of the reaction mixture. Taking into account the relative secondary ion yields of Co, La, and Sr cations estimated to be 0.11, 1 (chosen as a reference) and 3.6, respectively [7], a certain enrichment of the surface layer with Sr and Co might be inferred.…”

“…are expected to affect catalytic properties even more substantially than a continuous accumulation of point defects. Indeed, for a strontium-substituted lanthanum cobaltite La~.xSrxCoO3, transition from the orthorhombic to the cubic structure was earlier found to occur at x=0.4 [6,7]. A high degree of sample disordering was registered within the composition range of transition due to emergence of surface steps, clusters of a new phase and grain boundaries.…”