Papers by Mattias Thuvander
Materials, Mar 19, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Social Science Research Network, 2022
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2016
ACS Applied Materials & Interfaces, Feb 3, 2021
Silver alloying of Cu(In,Ga)Se 2 absorbers for thin film photovoltaics offers improvements in ope... more Silver alloying of Cu(In,Ga)Se 2 absorbers for thin film photovoltaics offers improvements in open-circuit voltage, especially when combined with optimal alkali-treatments and certain Ga concentrations. The relationship between alkali distribution in the absorber and Ag alloying is investigated here, combining experimental and theoretical studies. Atom probe tomography analysis is implemented to quantify the local composition in grain interiors and at grain boundaries. The Na concentration in the bulk increases up to ∼60 ppm for [Ag]/([Ag] + [Cu]) = 0.2 compared to ∼20 ppm for films without Ag and up to ∼200 ppm for [Ag]/([Ag] + [Cu]) = 1.0. First-principles calculations were employed to evaluate the formation energies of alkali-on-group-I defects (where group-I refers to Ag and Cu) in (Ag,Cu)(In,Ga)Se 2 as a function of the Ag and Ga contents. The computational results demonstrate strong agreement with the nanoscale analysis results, revealing a clear trend of increased alkali bulk solubility with the Ag concentration. The present study, therefore, provides a more nuanced understanding of the role of Ag in the enhanced performance of the respective photovoltaic devices.
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2020
Microstructure and properties of as-built laser powder bed fusion (LPBF) steels differ from the c... more Microstructure and properties of as-built laser powder bed fusion (LPBF) steels differ from the conventional ones, and they may contain some porosity and lack of fusion. Therefore, post-treatments, including hot isostatic pressing (HIP), are used to densify the material, and tailor the properties of the final product. Usually, HIP is performed as an operation separate from heat treatment. In the present investigation a new approach was used, in which the whole cycle of the heat treatment was carried out in HIP under pressure, and the influence of HIP on microstructure of an advanced stainless maraging tool steel manufactured by LPBF was investigated. For a comparison, a conventional steel grade of the same chemical composition, after a heat treatment at the same temperature-time conditions, was also characterized. The microstructure of the steel was investigated by means of advanced microscopy and atom probe tomography. The influence of the manufacturing route, heat treatment and HIP on microstructure, austenitic phase fraction and size distribution of precipitates was investigated, and the role of high pressure in stabilization of austenite in the microstructure was discussed. It was concluded that since HIP influences phase transformations, a fundamental understanding of the influence of HIP on microstructure is necessary, and development of new post processing regimes guaranteeing the best performance of the material is required.
Materials Characterization, Jun 1, 2023
Ultramicroscopy, Nov 1, 2022
Physical Review Materials, Aug 22, 2018
The Supplemental Material document includes 1. Movie Captions, 2. Methods (experimental and compu... more The Supplemental Material document includes 1. Movie Captions, 2. Methods (experimental and computational details), 3. Supplemental Discussions 1-5 and 4. Supplemental Figures S1-S4.
Journal of Radioanalytical and Nuclear Chemistry, May 21, 2022
substitution for UO 2 from a chemical point of view. ThO 2 is a highly insoluble compound, mainly... more substitution for UO 2 from a chemical point of view. ThO 2 is a highly insoluble compound, mainly due to the fact that ionic thorium only exists as the strong Lewis acid in the tetravalent oxidation state and, therefore, could potentially be able to protect the more redox sensitive and thus more soluble UO 2 from oxidation from the tetravalent to the hexavalent state and, ultimately, its dissolution in water. UO 2 is not per se more soluble in its tetravalent state than ThO 2 but can be readily oxidised to the hexavalent state and then dissolve. Dissolution of UO 2 may be a problem under different scenarios, for example, during interim storage of spent fuel, in a final repository, and in the case of fuel cladding failure during normal reactor operations. It is assumed that groundwater could intrude in the repository, and one of the scenarios that have been evaluated by SKB (The Swedish Nuclear Fuel and Waste Management Co) for the proposed KBS-3 concept for spent fuel management, is that the assumed reducing conditions in the water-filled repository would change to oxidizing conditions [5]. Together with a scenario with defective fuel canisters, this would increase the dissolution rate of the deposited fuel, which would then be in direct contact with groundwater. The radioactivity release from such a worst-case scenario would possibly be mitigated by partial substitution of UO 2 in the fuel
International Journal of Fatigue, Dec 1, 2016
Duplex stainless steels (DSS) have become candidate materials for structural applications, where ... more Duplex stainless steels (DSS) have become candidate materials for structural applications, where conventional austenitic stainless steels fail due to very high cycle fatigue (VHCF) in combination with corrosive attack. It seems that DSS exhibit a fatigue limit, which can be attributed to the two-phase austenitic-ferritic microstructure. Ultrasonic VHCF testing revealed that the phase boundaries are efficient obstacles for the transmission of slip bands and microstructural fatigue cracks up to 10 9 cycles and even beyond. The barrier strength is determined by the misorientation relationship between neighbouring grains but also by the strength of the individual phases. By thermal treatment at 475°C, spinodal decomposition of the ferrite phase results in the formation of Cr-rich a´ precipitates. While during static loading these precipitates give rise to a loss in ductility (475°C embrittlement), it was shown that the HCF strength can be increased and that there is also a tendency towards a beneficial effect on the VHCF behaviour. A more detailed analysis of the local plasticity sites by means of atom probe tomography (APT) revealed a dissolution of the a´ precipitates within operated slip bands. The dissolution might be an indication for a local softening mechanism that limits the VHCF strengthening effect of spinodal decomposition.
Journal of Applied Physics, Aug 3, 2015
Doping mechanisms of Mn in GaAs nanowires (NWs) that have been grown self-catalytically at 600 C ... more Doping mechanisms of Mn in GaAs nanowires (NWs) that have been grown self-catalytically at 600 C by molecular beam epitaxy (MBE) are investigated using advanced electron microscopy techniques and atom probe tomography. Mn is found to be incorporated primarily in the form of non-magnetic tetragonal Ga 0.82 Mn 0.18 nanocrystals in Ga catalyst droplets at the ends of the NWs, while trace amounts of Mn (22 6 4 at. ppm) are also distributed randomly in the NW bodies without forming clusters or precipitates. The nanocrystals are likely to form after switching off the reaction in the MBE chamber, since they are partially embedded in neck regions of the NWs. The Ga 0.82 Mn 0.18 nanocrystals and the low Mn concentration in the NW bodies are insufficient to induce a ferromagnetic phase transition, suggesting that it is difficult to have high Mn contents in GaAs even in 1-D NW growth via the vapor-liquid-solid process. V
Nuclear Materials and Energy
Nuclear Materials and Energy
Journal of Nuclear Materials
Journal of Nuclear Engineering
The development of coatings for accident-tolerant fuels (ATFs) for light water reactor (LWR) appl... more The development of coatings for accident-tolerant fuels (ATFs) for light water reactor (LWR) applications promises improved corrosion resistance under accident conditions and better performances during operation. CrN and TiN coatings are characterized by high wear resistance coupled with good corrosion resistance properties. They are generally used to protect materials in applications where extreme conditions are involved and represent promising candidates for ATF. Zr cladding tubes coated with 5 µm-thick CrN or TiN, exposed in an autoclave to simulated PWR chemistry and BWR chemistry, were characterized with SEM, EDS, and STEM. The investigation focused on the performance and oxidation mechanisms of the coated claddings under simulated reactor chemistry. Both coatings provided improved oxidation resistance in a simulated PWR environment, where passivating films of Cr2O3 and TiO2, less than 1 µm-thick, formed on the CrN and TiN outer surfaces, respectively. Under the more challengin...
Journal of Nuclear Materials, 2022
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Papers by Mattias Thuvander