Oxygen diffusion in the orthorhombic FeNbO₄ material: a computational study

Area of Science:

• Materials Science
• Computational Chemistry
• Solid-State Physics

Background:

• ABO4-type materials are promising for luminescence and photocatalysis.
• Orthorhombic iron niobate (o-FeNbO4) shows potential for catalytic electrodes.
• Computational simulation of o-FeNbO4 is challenging due to its disordered nature.

Purpose of the Study:

• To computationally investigate the ordered structure of o-FeNbO4.
• To determine the bulk properties and oxygen diffusion pathways in o-FeNbO4.
• To assess the impact of disorder and vacancies on o-FeNbO4 properties for electrode applications.

Main Methods:

• Force field parameter validation using GULP code.
• Analysis of cation disorder probabilities in supercells.
• Density Functional Theory (DFT) calculations for bulk properties.
• Simulation of oxygen diffusion pathways in stoichiometric and non-stoichiometric structures.

Main Results:

• An ordered configuration of stoichiometric o-FeNbO4 was identified as dominant.
• DFT calculations showed bulk properties comparable to monoclinic FeNbO4.
• Oxygen vacancies were found to enhance oxygen diffusion.
• Lattice distribution of Fe and Nb influences diffusion energy barriers.

Conclusions:

• The study provides insights into the dominant ordered structure of o-FeNbO4.
• Computational methods were validated for simulating disordered materials.
• Oxygen mobility in o-FeNbO4 is influenced by vacancies and cation distribution, critical for electrode applications.