Theoretical Study of Cubic and Orthorhombic Nd 1– x Sr x MnO 3 as a Potential Solid Oxide Fuel Cell Cathode

In this paper, the atomic and electronic structures of cubic and orthorhombic Nd 1– x Sr x MnO 3 are investigated using the projector augmented‐wave (PAW) methods within the spin‐polarization generalized gradient approximation (GGA+ U ), where U is on‐site Coulomb interaction correction. The optimized structure parameters of both cubic and orthorhombic bulk phases are obtained. The difference between the AFM and FM structures for NdMnO 3 is very small, indicating a small magneto‐elastic effect. In Nd 1– x Sr x MnO 3 , the pseudo‐cubic lattice constant decreases on increasing Sr doping due to the oxidation of Mn 3+ cations to the smaller Mn 4+ cations. The result of the total density of states shows the majority spin without gap and the minority spin with 4.8 × 10 −19  J gap, indicating a half‐metallic ground state for NdMnO 3 in GGA+ U treatment. The Bader effective charges in both cubic and orthorhombic phases are analyzed. The oxygen vacancy formation energy of Nd 1– x Sr x MnO 3 becomes smaller as the Sr doping concentration increases. The oxygen vacancies can be formed more easily on Nd 0.5 Sr 0.5 MnO 3 than other systems. These results suggest that Nd 0.5 Sr 0.5 MnO 3 could be a promising candidate for application in SOFC.