Effect of the synthesis route on the microstructure and the reducibility of LaCoO3

Isothermal reverse water gas shift chemical looping on La0.75Sr0.25Co(1−)Fe O3 perovskite-type oxides

“…The first (lowtemperature) region corresponded to formation of oxygen vacancies in the structure of the material as a consequence of changes in the oxidation state of Co and Fe possibly changing from Co 4+ to Co 3+ , Co 3+ to Co 2+ [32] and Fe 4+ to Fe 3+ [30] respectively. The second (high-temperature) region corresponded to the reduction of the oxygen-vacant perovskite into its base oxides [32,44] and metal phases [45] for the Co-containing samples (with reduction proportional to their Co content), and predominantly oxygen vacancies formation on the Fe-rich perovskites [30], although Fe 0 has been detected by XRD on Y = 0.8 samples after reduction under H 2 at 800 • C [39]. The TPR profiles showed that as the Fe:Co ratio increases, the two reduction regions shifted to higher temperatures and the TPR profiles decreased in intensity.…”

“…The molar ratios of the precursors used was (A site:B site:citric acid:ethylene glycol = 1:1:10:40) following the synthesis method of Ivanova et al [32].…”

Effect of Er substitution on ultrasonic anomaly in Dy0.5−xErxBa0.5CoO3 cobaltates

“…Rare-earth (RE) cobaltates with provskite structure of the general composition of the type RECoO 3 and hole-doped RE 1Àx A x CoO 3 as well as their half-doped RE 0.5 A 0.5 CoO 3 (where RE is a trivalent rare-earth ion such as La, Nd, Dy, and Gd, and A is a divalent alkaline-earth ion such as Sr, Ca or Ba) have been given fair attention in a recent years due to their unique magnetic and transport properties as well as the potential application [1][2][3][4][5][6]. In addition to the lattice, charge and spin degrees of freedom which are found in many other transition metal oxides, the cobaltates also display interesting features originating from the 'spin state' at Co-site [7,8].…”

Effect of different solvents in the synthesis of LaCoO3 nanopowders prepared by the co-precipitation method

“…Armelao et al [20] prepared LaCoO 3 by two process namely combustion synthesis and molten chloride flux process at 800°C for 17 h and 950°C for 24 h respectively. Ivanova et al [21] have also successfully synthesized LaCoO 3 powders by two techniques: (i) pechini route from the aqueous solution of citric acid to a suspension of CoCO 3 in aqueous solution of La(NO 3 ) 3 .6H 2 O and (ii) conventional solid state reaction between La 2 O 3 and CoCO 3 . In the pechini process, pure LaCoO 3 phase was obtained by calcining at 600°C for 20 h whereas in conventional solid state process, pure LaCoO 3 was obtained by annealing at 800°C for 20 h. Gaki et al [11] pointed that the polymerizable complex method can be successfully applied for the preparation of LaCoO 3 .…”