Charge transfer in FeO: a combined molecular-dynamics and ab initio study

Area of Science:

• Materials Science
• Solid-State Physics
• Computational Chemistry

Background:

• Stoichiometric wustite (FeO) exhibits charge transfer via Fe(II)/Fe(III) valence interchange.
• Understanding charge transfer mechanisms is crucial for predicting electrical properties of transition metal oxides.

Purpose of the Study:

• To determine the rates of charge transfer in stoichiometric wustite.
• To investigate the factors influencing charge transfer, including lattice structure and defects.
• To predict the electrical conductivity anisotropy of wustite.

Main Methods:

• Molecular-dynamics simulations were employed to model charge transfer pathways.
• Ab initio electronic structure calculations provided complementary rate data.
• A mechanical shell model was used to account for polarizability changes during charge transfer.

Main Results:

• Calculated charge transfer rates for edge-sharing and corner-sharing FeO(6) octahedra were in good agreement between simulation methods.
• Wustite is predicted to exhibit anisotropic electrical conductivity, similar to hematite.
• Oxygen vacancies were found to lower charge transfer barriers and influence reorganization energy.

Conclusions:

• The study highlights the necessity of including polarizability effects for accurate charge transfer modeling in wustite.
• Lattice structure and oxygen vacancies significantly impact charge transport properties.
• The findings provide fundamental insights into the electronic behavior of wustite.