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MM: Fachverband Metall- und Materialphysik
MM 8: Materials for the Storage and Conversion of Energy II
MM 8.5: Vortrag
Montag, 9. März 2026, 16:45–17:00, SCH/A216
Defect Landscape of Ba2In2O5: The Role of Oxygen Interstitials — •Rachele Sciotto and Karsten Albe — achgebiet Materialmodellierung, Institut für Materialwissenschaft, Technische Universität Darmstadt, Otto-Berndt-Str. 3, D-64287 Darmstadt, Germany
Ba2In2O5 (BIO) is a promising n-type mixed ionic and electronic conductor (MIEC) for oxygen permeation membranes and solid oxide fuel cells (SOFCs). At ambient conditions, BIO adopts an orthorhombic brownmillerite structure with alternating InO6 octahedral and InO4 tetrahedral layers that can host interstitial oxygen atoms at sites of structural vacancies. Existing defect thermodynamics models consider only this type of oxygen interstitial; however, oxygen interstitials forming O-O dumbbells, found in oxides like ZnO and In2O3, are also possible. In this work, we investigate the potential existence of O-O dumbbells in BIO using density functional theory (DFT). By calculating formation enthalpies as a function of Fermi level and concentrations as a function of oxygen chemical potential, we identify two distinct classes of interstitial configurations. Neutral O-O dumbbells are stabilized over a wide Fermi-level range, while negatively charged interstitials at the structural oxygen vacancy site become favorable under n-type conditions. Although the neutral dumbbells do not contribute to charge compensation, they form in high concentrations. They could therefore serve as intermediate positions for oxygen diffusion pathways, thereby influencing the material’s ionic and electronic conductivity.
Keywords: Barium indate; Oxygen interstitials; Defect thermodynamics; Density functional theory; Charge compensation