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The interaction of ...
The interaction of hydrogen with metallic glass
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- Bylin, Johan (författare)
- Uppsala universitet,Materialfysik
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- Pálsson, Gunnar K., Associate Professor (preses)
- Uppsala universitet,Materialfysik
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- Scheicher, Ralph H., Researcher (preses)
- Uppsala universitet,Materialteori
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- Andersson, Gabriella, Professor, 1972- (preses)
- Uppsala universitet,Materialfysik
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- Pundt, Astrid, Professor Dr (opponent)
- Karlsruher Institut für Technologie, Germany
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(creator_code:org_t)
- ISBN 9789151320755
- Uppsala : Acta Universitatis Upsaliensis, 2024
- Engelska 82 s.
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Serie: Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 ; 2376
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Abstract
Ämnesord
Stäng
- Combining theoretical ab initio calculations with high-purity thin film sample synthesis and in situ measurements is a compelling way to bridge the gap in our understanding concerning hydrogen in metallic glasses, which is the primary work of this dissertation thesis. The main emphasis has been on how hydrogen affects the structure of metallic glasses, and how those changes influence not only the electronic properties of the amorphous metals but also their thermal stability. The real-space correlations in the form of the pair distribution functions in thin metallic films have primarily only been accessible through synchrotron radiation. An effective methodological procedure using laboratory-based x-ray sources is here brought forth, which, for the first time, can produce accessible and accurate pair distribution functions from thin films down to a thickness of 80 nm. The underpinning mechanisms behind the hydrogen-induced volume expansion of metallic glasses in the form of the dipole force tensor and an elastic hydrogen-hydrogen interaction were examined using in situ neutron reflectometry and first-principles calculations of expanding V80Zr20 amorphous structures. The dipole force tensor was concluded to be similar in magnitude to a mole-fraction-weighted sum of the ones found in hydrogen-contained vanadium and zirconium crystals, and the theoretical calculations demonstrated that it and the interaction energy varies with hydrogen concentration. The electronic structure of the metallic glass V80Zr20 was determined via hard x-ray photoemission spectrometry and confirmed by first-principles calculations to be modified by the presence of hydrogen, in which a collection of s-d hybridized states 7 eV below the Fermi level was formed. The changes closer to the Fermi level, together with the volume expansion, were via experiments and ab initio calculations established to cause a parabolic change in resistance and a strong wavelength dependence on the optical transmission. The thermal stability of amorphous VxZr1-x metals, investigated via ab initio calculations of the thermodynamic driving force towards crystallization, was found to affirm the observed hydrogen-induced enhancement in thermal stability.
Ämnesord
- NATURVETENSKAP -- Fysik -- Den kondenserade materiens fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Condensed Matter Physics (hsv//eng)
Nyckelord
- metallic glass
- hydrogen
- thin film
- density functional theory
- stochastic quenching
- molecular dynamics
- x-ray diffraction
- pair distribution function
- neutron reflectometry
- volume expansion
- elastic hydrogen-hydrogen interaction
- dipole force tensor
- electronic structure
- optical conductivity
- resistivity
- optical transmission
- x-ray photoelectron spectroscopy
- thermodynamic driving force
- Gibbs free energy
- Physics with spec. in Atomic, Molecular and Condensed Matter Physics
- Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik
Publikations- och innehållstyp
- vet (ämneskategori)
- dok (ämneskategori)
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