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Trial lecture
September 22nd, 10:30 AM, Auditorium 3, Chemistry building
Trial lecture title: "Proton conducting oxides: what is the most important materials family (and 1-2 other structures), proton transport mechanism, similarities and differences to oxide ion conductors"
Kreeringssammendrag/Conferral summary
Dette arbeidet demonstrerer den sterke ytelsen til faste Bi2O3-baserte og smelte-fast fase V2O5-baserte kompositter når det gjelder oksygenfluks og oksygenutvekslingskinetikk, og bidrar til en grunnleggende forståelse av transportmekanismer og kinetikk i både bulk og overflate for blandet ledende komposittoksider. Reaksjonsveier og hastighetsbegrensende prosesser undersøkes ved hjelp av en kombinasjon av elektrokjemiske målinger, oksygenfluksmålinger og 18O-16O isotoputvekslingsteknikker.
Main research findings
Oxygen-permeable ceramics are essential for gas separation and electrochemical technologies, including applications in the steel and chemical industries, as well as in low-carbon or clean energy systems such as oxyfuel combustion and solid oxide fuel cells. However, slow oxygen reduction and evolution at the surfaces often hinder the development of these materials, highlighting the need for a deeper understanding of reaction pathways and rate-limiting steps in the oxygen exchange mechanism.
This work demonstrates the notable oxygen flux and surface kinetics of Tm-doped Bi2O3- (BTM) and (La0.8Sr0.2)0.99MnO3-δ (LSM) composites - on par with state-of-the art oxygen permeable membranes - and offers fundamental insights into the surface processes in mixed-conducting dual-phase materials. Furthermore, oxide melts - with their lower activation barriers for oxygen transport and kinetics - are promising candidates for operation at intermediate temperatures. The literature on oxygen transport in melts is limited, and on surface kinetics, virtually non-existent. We present the first in-situ investigation of oxygen transport and surface exchange across the solid-liquid transition in V2O5, both as a single-phase material and as part of a ZrV2O7-30mol%V2O5 composite. Reaction rates increase by several orders of magnitude during the melting of V2O5.
Candidate contact information
lkemhjel@uio.no
91605056
Adjudication committee
Scientist Rotraut Merkle
Max Planck Institute for Solid State Research, Germany
Professor Wilhelm Albert Meulenberg
Forschungszentrum Jülich GmbH, Germany
Professor Ola Nilsen
Department of Chemistry, University of Oslo, Norway
Supervisors
Professor Reidar Haugsrud
Department of Chemistry, University of Oslo, Norway
Research Fellow Tor Svendsen Bjørheim
Department of Chemistry, University of Oslo, Norway
Chair of defence
Professor Harald Walderhaug
Department of Chemistry, University of Oslo, Norway