Formation add migration of cation defects in the perovskite oxide LaMnO3

Atomistic simulation techniques have been employed to investigate the energ etics of cation formation and migration in cubic, rhombohedral and orthorho mbic LaMnO3. The calculations suggest that for rhombohedral and orthorhombi c lanthanum manganite, oxidative nonstoichiometry leads to-the formation of cation vacancies on both La and Mn sites, though tending towards more La v acancies, The activation energy for,lanthanum vacancy migration was found t o increase with departure from cubic perovskite symmetry in the order: cubi c < rhombohedral < orthorhombic. A number of different pathways for mangane se vacancy migration were examined. The lowest energy pathway was found to be a Curved path between Mn sites that are adjacent along the < 100 > (cubi c) directions. Calculated migration energies for this path also increased w ith distortion from the cubic form. The effect of composition on cation mig ration energies was also examined.