Co?Substituted BiFeO ₃ : Electronic, Ferroelectric, and Thermodynamic Properties from First Principles

Bismuth ferrite, BiFeO3, is a multiferroic solid that attracting increasing attention as potential photocatalytic material, because the ferroelectric polarization enhances separation of photogenerated carriers. With motivation finding routes to engineer band gap and alignment, while conserving or enhancing properties, thermodynamic, electronic, properties BiCoxFe1?xO3 solutions (x = 0, 0.0625, 0.125) using density functional theory are investigated. It shown can be reduced from 2.9 2.1 eV by cobalt substitution, simultaneously spontaneous polarization, which associated with notably larger Born effective charge Co compared Fe cations. The interaction between impurities discussed, strongly attractive drive aggregation Co, evidenced Monte Carlo simulations. Phase into Co-rich phase therefore predicted thermodynamically preferred, homogenous solution only exist in metastable form, protected slow cation diffusion kinetics. Finally, alignment pure Co-substituted BiFeO3 relevant redox potentials, context its applicability photocatalysis, discussed.