A Novel, Simple and Highly Efficient Route to Obtain PrBaMnO Double Perovskite: Mechanochemical Synthesis.

In this work, a mechanochemical route was proposed for the synthesis of the PrBaMnO (PMBO) double layered perovskite phase. The mechanochemical reaction between PrO, BaO, 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 PrBaMnO phase was formed. When this new phase was subsequently annealed at a high temperature in an inert Ar atmosphere, the layered PrBaMnO phase was obtained without needing to use a reducing atmosphere. At 1100 °C, the fully reduced layered PrBaMnO 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 PrBaMnO phase. The microstructural characterization by SEM, TEM, and HRTEM ascertained the formation of the intended PrBaMnO 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).