Mechanistic Elucidation of Surface Cation Segregation in Double Perovskite PrBaCo2O5+δ Material using MD and DFT Simulations for Solid Oxide Fuel Cells

Progress in Developing LnBaCo2O5+δ as an Oxygen Reduction Catalyst for Solid Oxide Fuel Cells

“…According to Lee et al [206], the segregation originates from the dopant's elastic and electrostatic interactions with the host lattice. A slight size mismatch between the dopant and host cations could reduce this segregation, promoting a more stable cathode surface [205][206][207][208][209][210][211][212][213][214][215]. Nonetheless, the majority of research on the surface microstructure of double perovskite cathodes relies on basic sintering processes in the air, which differs significantly from actual battery operating conditions.…”

Segregation and interdiffusion processes in perovskites: a review of recent advances

“…Calculations of the surface segregation of A-cations in double perovskite electrodes were performed using a combined theoretical approach based on density functional theory and molecular dynamics. 107–109 The simulation results revealed that the migration of oxygen anions and the creation of oxygen vacancies are least favoured in the Ba-plane for PrBaCo 2 O 5+ δ , GdBaCo 2 O 5+ δ , and PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+ δ . The surface containing Ba cations is the most stable due to migration of cations from near-surface region to the surface, which promotes the structure cleavage and evolution of new phases.…”

Controlling surface cation segregation in a double perovskite for oxygen anion transport in high temperature energy conversion devices

“…6,7 More specifically, the A 0 -site cation in the structure is observed to preferentially segregate to the surface, forming a secondary oxide phase. [8][9][10][11] In order to reduce surface cation segregation, strategies may be adapted in the design and synthesis of the materials, which may provide desired breakthroughs in the development of electrodes for energy storage devices. In the present work, two such strategies are investigated using theoretical simulations employing molecular dynamics (MD) and density functional theory (DFT) to control cation segregation and provide a molecular-level rationale for electrode design.…”

“…Thus, a specific focus on Ba cations, entailing their partial substitution, may provide a recipe for reducing segregation. In general, a trial approach in substitution is attempted for synthesizing high-performance electrode materials, which has led to a variety of co-doped double perovskite structures, 10,13 such as PrBa 1Àx Sr x Co 2Ày Fe y O 5+d (PBSCF). Our group has synthesized PBSCF as a geometrically well-defined thin-film electrode to assess the limitations in its electrochemical performance arising from surface cation segregation.…”