dc.contributor.author | Hoedl, Maximilian F. | |
dc.contributor.author | Gryaznov, Denis | |
dc.contributor.author | Merkle, Rotraut | |
dc.contributor.author | Kotomin, Eugene A. | |
dc.contributor.author | Maier, Joachim | |
dc.date.accessioned | 2020-08-27T13:57:15Z | |
dc.date.available | 2020-08-27T13:57:15Z | |
dc.date.issued | 2020 | |
dc.identifier.issn | 1932-7447 | |
dc.identifier.uri | https://dspace.lu.lv/dspace/handle/7/52496 | |
dc.description | Financial support by the German–Israeli Foundation for Scientific Research and Development (grant I-1342-302.5/2016) and the Latvian Council of Science (grant lzp-2018/1-0147 (D.G., E.A.K.)) is gratefully acknowledged. The authors further thank Guntars Zvejnieks for help with CRYSTAL code calculations. | en_US |
dc.description.abstract | Protonic-electronic mixed-conducting perovskites are relevant as cathode materials for protonic ceramic fuel cells (PCFCs). In the present study, the relation between the electronic structure and the thermodynamics of oxygen nonstoichiometry and hydration is investigated for BaFeO3-δ and Ba0.5Sr0.5FeO3-δ by means of density functional theory. The calculations are performed at the PBE + U level and yield ground-state electronic structures dominated by an oxygen-to-metal charge transfer with electron holes in the O 2p valence bands. Oxygen nonstoichiometry is modeled for 0 ≤ δ≤ 0.5 with oxygen vacancies in doubly positive charge states. The energy to form an oxygen vacancy is found to increase upon reduction, i.e., decreasing concentration of ligand holes. The higher vacancy formation energy in reduced (Ba,Sr)FeO3-δ is attributed to a higher Fermi level at which electrons remaining in the lattice from the removed oxide ions have to be accommodated. The energy for dissociative H2O absorption into oxygen vacancies is found to vary considerably with δ, ranging from ≈-0.2 to ≈-1.0 eV in BaFeO3-δ and from ≈0.2 to ≈-0.6 eV in Ba0.5Sr0.5FeO3-δ. This dependence is assigned to the annihilation of ligand holes during oxygen release, which leads to an increase in the ionic charge of the remaining lattice oxide ions. The present study provides sound evidence that p-type electronic conductivity and the susceptibility for H2O absorption are antagonistic properties since both depend in opposite directions on the concentration of ligand holes. The reported trends regarding oxygenation and hydration energies are in line with the experimental observations. | en_US |
dc.description.sponsorship | Latvian Council of Science lzp-2018/1-0147; German–Israeli Foundation for Scientific Research and Development grant I-1342-302.5/2016; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART² | en_US |
dc.language.iso | eng | en_US |
dc.publisher | American Chemical Society | en_US |
dc.relation | info:eu-repo/grantAgreement/EC/H2020/739508/EU/Centre of Advanced Material Research and Technology Transfer/CAMART² | en_US |
dc.relation.ispartofseries | The Journal of Physical Chemistry C;120 | |
dc.rights | info:eu-repo/semantics/openAccess | en_US |
dc.subject | Research Subject Categories::NATURAL SCIENCES:Physics | en_US |
dc.title | Interdependence of Oxygenation and Hydration in Mixed-Conducting (Ba,Sr)FeO3-δPerovskites Studied by Density Functional Theory | en_US |
dc.type | info:eu-repo/semantics/article | en_US |
dc.identifier.doi | 10.1021/acs.jpcc.0c01924 | |