A Novel, Simple and Highly Efficient Route to Obtain PrBaMn(2)O(5+δ) Double Perovskite: Mechanochemical Synthesis

In this work, a mechanochemical route was proposed for the synthesis of the PrBaMn(2)O(5+δ) (PMBO) double layered perovskite phase. The mechanochemical reaction between Pr(6)O(11), BaO(2), and MnO powders with cationic stoichiometric ratios of 1/1/2 for Pr/Ba/Mn was performed using high-energy milling conditions in air. After 150 min of milling, a new phase with perovskite structure and cubic symmetry consistent with the A-site disordered Pr(0.5)Ba(0.5)MnO(3) phase was formed. When this new phase was subsequently annealed at a high temperature in an inert Ar atmosphere, the layered PrBaMn(2)O(5+δ) phase was obtained without needing to use a reducing atmosphere. At 1100 °C, the fully reduced layered PrBaMn(2)O(5) phase was achieved. A weight gain was observed in the 200–300 °C temperature range when this fully reduced phase was annealed in air, which was consistent with the transformation into the fully oxidized PrBaMn(2)O(6) phase. The microstructural characterization by SEM, TEM, and HRTEM ascertained the formation of the intended PrBaMn(2)O(5+δ) phase. Electrical characterization shows very high electrical conductivity of layered PBMO in a reducing atmosphere and suitable in an oxidizing atmosphere, becoming, therefore, excellent candidates as solid oxide fuel cell (SOFC electrodes).