Structural transformations in cubic structure of Mn/Co perovskites in reducing and oxidizing atmospheres

ABO3ABO3 (A=La, Pr; B  =Mn, Co), AB1−xBx′O3 (A=La, Pr; B  =Mn, Co; B′=B′=Co, Pd), and AB1−x−yCoyPdxO3AB1−x−yCoyPdxO3 (A=La, Pr; B  =Fe, Mn) (x=0.05x=0.05, 0.37; y=0.38y=0.38) perovskites were synthesized via malic acid complexation. O2-TPD, O2-TPO, and H2-TPR treatments were carried out to study the oxidation and reduction behavior of the synthesized perovskites. LaCo0.95Pd0.05O3, PrCo0.95Pd0.05O3, and PrCoO3 perovskites had the highest desorption, oxidation, and reduction activity within the studied perovskite series. Powder XRD studies revealed structural transformation of the cubic structure of all synthesized perovskites except LaFe0.57Co0.38Pd0.05O3 in H2/Ar atmosphere when the temperature was over 400 °C. The decomposed structure reverted to the original perovskite structure under oxidizing atmosphere. This reversion was accompanied by increased oxygen desorption activity. It was noticed that the Co and Mn combinations in the B-site of the perovskites structure decreased the thermal stability of the synthesized perovskites.

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