Disputation: Liv-Elisif Queseth Kalland
MSc. Liv-Elisif Queseth Kalland at the Department of Chemistry, Faculty of Mathematics and Natural Sciences, is defending the thesis « Ab-initio modelling and experimental study of order-disorder, hydration, and ionic conductivity of fluorite-related oxides » for the degree of Philosophiae Doctor.
Due to the ongoing Pandemic, the Disputation will be held digital using Zoom. The Chair of Defence will lead the Disputation and the Defence technician will solve technical issues.
Ex auditorio questions: The Chair of Defence will invite the audience to ex auditorio questions. These can be asked orally, by clicking "Participants - Raise hand" in the Zoom menu. The Zoom-host will grant you to speak in the meeting.
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22th. of Jan. at 10:30 AM, Zoom
Title:"Importance of protons in battery design"
Protonledende oksider er mulige faste elektrolytter i bærekraftige elektrokjemiske prosesser innen energikonvertering med hydrogen som energibærer og i produksjonen av hydrogenholdige kjemikalier. Liv-Elisif Queseth Kalland har med eksperimentelle og teoretiske metoder studert sammenhengen mellom ioneledningsevnen og uorden i krystallstrukturen til et utvalg protonledende oksider med fluorittrelaterte strukturer. Arbeidet viser hvordan ordning av defektene i strukturen ikke bare begrenser oksidion-ledningsevnen, men også opptaket av protoner fra vanndamp og derved proton-ledningsevnen.
Main research findings
Hydrogen will play a key role in a zero-emission society, and proton (H+) conducting oxides have gained interest as solid-state electrolytes for next-generation electrochemical devices for fuel cells and electrolyzers. Understanding the effect of structure on materials functional properties is important for enhancing the performance of such electrolytes. Oxides with fluorite related crystal structures are interesting for their high oxide ion and proton (H+) conductivities, and in this work the relationship between the atomic structure and the materials properties such as ionic conductivity and hydration properties have been studied for three different oxides. They are oxygen deficient with respect to the fluorite structure and the vacant oxide ion sites can thus be ordered or disordered. Through a combination of different experimental and computational methods the nature and degree of ordering and the atomic structure have been determined, and correlated to the properties of the cations present, such as size and electronegativity. The work further focuses on whether ordering the oxide ion vacancies affects the hydration and consequently the proton conductivity. The results have led us to propose a new model for hydration of heavily doped yet disordered fluorite oxides.