Theoretical investigation of iron incorporation in hexagonal barium titanate

The incorporation of Fe impurities in hexagonal barium titanate is studied in the framework of density functional theory. Formation energies are calculated to find the most probable defect structure. The substitution of Fe at the two inequivalent Ti sites accompanied by oxygen vacancies in different positions is studied. Additionally, different charge states of defects are taken into account. The structural aspects of the different defects are also studied in detail. In summary, the theoretical results are in agreement with recent experimental results found by means of electron paramagnetic resonance.