Alloy exsolution in co-doped PrBaMn2-xTMxO5+δ (TM = Co and/or Ni) obtained by mechanochemistry

Doped-PrBaMn 2-x TM x O 5+δ samples with TM = Co and/or Ni were synthesized by a mechanochemical route from stoichiometric oxide precursor mixtures (Pr 6 O 11 , BaO 2 , MnO, NiO and CoO) using a planetary mill at 600 rpm for 150 min. A disordered ABO 3 pseudocubic perovskite phase was obtained after the milling process that was transformed, as established by XRD, into the double layered AA’B 2 O 5+δ perovskite phase after annealing at 900 °C in a reducing atmosphere (10%H 2 /Ar). The microstructural characterization by SEM, TEM, and HRTEM ascertained that this reducing treatment induced the exsolution of Ni and Co metallic nanoparticles from the doped samples. Ni-Co alloys were even exsolved when the layered manganite phase was co-doped with both transition metals. It was confirmed that the exsolution process was reversible by switching the working atmosphere from reducing to oxidizing. Polarization resistance values of the doped samples determined in symmetrical cells in air and H 2 , as well as the electrochemical performance of electrolyte LSGM-supported planar cells suggested that these samples can be used as symmetrical electrodes in SOFCs. • Highly efficient fabrication of PrBaMn 2-x TM x O 5+δ ( TM = Co, Ni) by mechanosynthesis. • Formation of double layered PrBaMn 2 O 5+δ perovskite phase in reducing atmosphere. • Exsolution of Ni and Co metallic nanoparticles in reducing atmosphere. • Enhanced ORR and HRR activities in both reducing and oxidizing atmospheres. • High power densities on symmetrical cell with PrBaMn 1.7 Ni 0.225 Co 0.075 O 5+δ electrode.