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Systematic investigation of positron annihilation in metallic materials using first-principles
KTH, School of Engineering Sciences (SCI), Physics, Nuclear Engineering.ORCID iD: 0000-0002-2808-9372
KTH, School of Engineering Sciences (SCI), Physics, Nuclear Engineering.ORCID iD: 0000-0002-2381-3309
2022 (English)In: Article in journal (Other academic) Submitted
Abstract [en]

In this work, we present a systematic theoretical study on the positron annihilation in transition metals and other elements (C, Al, Si and P). The two-component density functional theory is utilized to calculate the positron annihilation characteristics (positron lifetimes and momentum distributions) in materials. Our calculations agree well with available reference experimental and theoretical data. We show that there exist clear trends on positron annihilation characteristics in materials. For the momentum distribution (Doppler broadening spectra), clear patterns are shown in 3d, 4d and 5d metal series with d-band filling. The characteristics of the Doppler spectra of transition metal elements are clearly presented. For the positron lifetime calculations, the lifetimes of transition metals evolve with their d-band filling in a similar behavior as their atomic volumes. We also show that the positron lifetimes have a linear relation with the atomic volumes for the same series. This work is expected to improve the understanding of the annihilation characteristics of elements. The results could be used to identify the defects in alloys, such as Fe-based alloys and high entropy alloys.

Place, publisher, year, edition, pages
2022.
National Category
Other Physics Topics
Research subject
Physics, Nuclear Engineering
Identifiers
URN: urn:nbn:se:kth:diva-319597OAI: oai:DiVA.org:kth-319597DiVA, id: diva2:1700941
Note

QC 20221005

Available from: 2022-10-04 Created: 2022-10-04 Last updated: 2022-10-06Bibliographically approved
In thesis
1. Modelling of radiation damage and positron annihilation in metallic materials
Open this publication in new window or tab >>Modelling of radiation damage and positron annihilation in metallic materials
2022 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The radiation damage is one of the key concerns in the research of materials used in radiation environments. In this thesis, we theoretically investigate the radiation damage phenomenon by focusing on two important topics: the defect production and evolution, and the defect characterization. 

The first part aims at two aspects. Firstly, a full energy range primary radiation damage model is presented based on modifying the athermal recombination corrected displacements per atom (arc-dpa) model. This modified full energy range model is validated by classical and ab initio molecular dynamics. Then, the modified model is used to estimate the radiation damage in electron-irradiated iron alloys and perform a systematic cluster dynamics study. The Cu precipitation in experiment is reproduced by the cluster dynamics model. This model is then used to predict the Cu precipitation in spent-fuel canisters up to 105 years. 

The second part focuses on positron annihilation in metallic materials. Positron annihilation spectroscopy (PAS) is a useful technique to characterize the ultrafine defects in materials. In this part, the state-of-the-art two-component density functional theory (TCDFT) is used to calculate the positron annihilation characteristics (positron lifetimes and Doppler broadening spectra) in materials. Firstly, a case study is performed in Fe-Cu system. Both vacancyfree Cu clusters and vacancy-Cu complexes are investigated. Then, a more systematic investigation is conducted to calculate the positron annihilation in transition metals. Finally, the positron annihilation in vacancy defects in tungsten is investigated by combining both experimental and theoretical results. The limitation of commonly used Boroński-Nieminen local density approximation is discussed.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2022
Series
TRITA-SCI-FOU ; 2022:49
Keywords
Radiation damage, First-principles, Positron annihilation spectroscopy, Cu precipitation, Two-component density functional theory, Tungsten, Transition metals
National Category
Other Physics Topics
Research subject
Physics, Nuclear Engineering; Physics
Identifiers
urn:nbn:se:kth:diva-319695 (URN)978-91-8040-384-9 (ISBN)
Public defence
2022-10-28, F3, Lindstedtsvägen 26,, Stockholm, 14:00 (English)
Opponent
Supervisors
Available from: 2022-10-06 Created: 2022-10-06 Last updated: 2022-10-06Bibliographically approved

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Yang, QiguiOlsson, Pär

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