liu.seSök publikationer i DiVA
Ändra sökning
Avgränsa sökresultatet
1 - 9 av 9
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Lin, Shuyao
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. Tech Univ Wien, Austria.
    Casillas-Trujillo, Luis
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Mayrhofer, Paul H.
    Tech Univ Wien, Austria.
    Sangiovanni, Davide
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Koutna, Nikola
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Tech Univ Wien, Austria.
    Machine-learning potentials for nanoscale simulations of tensile deformation and fracture in ceramics2024Ingår i: npj Computational Materials, E-ISSN 2057-3960, Vol. 10, nr 1, artikel-id 67Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Machine-learning interatomic potentials (MLIPs) offer a powerful avenue for simulations beyond length and timescales of ab initio methods. Their development for investigation of mechanical properties and fracture, however, is far from trivial since extended defects-governing plasticity and crack nucleation in most materials-are too large to be included in the training set. Using TiB2 as a model ceramic material, we propose a training strategy for MLIPs suitable to simulate mechanical response of monocrystals until failure. Our MLIP accurately reproduces ab initio stresses and fracture mechanisms during room-temperature uniaxial tensile deformation of TiB2 at the atomic scale ( approximate to 103 atoms). More realistic tensile tests (low strain rate, Poisson's contraction) at the nanoscale ( approximate to 104-106 atoms) require MLIP up-fitting, i.e., learning from additional ab initio configurations. Consequently, we elucidate trends in theoretical strength, toughness, and crack initiation patterns under different loading directions. As our MLIP is specifically trained to modelling tensile deformation, we discuss its limitations for description of different loading conditions and lattice structures with various Ti/B stoichiometries. Finally, we show that our MLIP training procedure is applicable to diverse ceramic systems. This is demonstrated by developing MLIPs which are subsequently validated by simulations of uniaxial strain and fracture in TaB2, WB2, ReB2, TiN, and Ti2AlB2.

  • 2.
    Casillas-Trujillo, Luis
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. Uppsala Univ, Sweden.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Effect of magnetic disorder on Cr interaction with 1/2 < 111 > screw dislocations in bcc iron2023Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 133, nr 12, artikel-id 125103Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate how the magnetic state influences the interaction of Cr substitutional impurities with 1/2?111? screw dislocations in bcc Fe via density functional theory (DFT). We compare the paramagnetic state, modeled with a non-collinear disordered local moment (DLM) model, with the ferromagnetic state. In a previous work [Casillas-Trujillo et al., Phys. Rev. B 102, 094420 (2020)], we have shown that the magnetic moment and atomic volume landscape around screw dislocations in the paramagnetic state of iron are substantially different from that in the ferromagnetic state. Such a difference can have an impact in the formation energies of substitutional impurities, in particular, magnetic solutes. We investigate the formation energies of Cr solutes as a function of position with respect to the screw dislocation core, the interaction of Cr atoms along the dislocation line, and the segregation profile of Cr with respect to the dislocation in paramagnetic and ferromagnetic bcc iron. Our results suggest that with increasing temperature and connected entropic effects, Cr atoms gradually increase their occupation of dislocation sites, close to twice the amount of Cr in the DLM case than in the ferromagnetic case, with possible relevance to understand mechanical properties at elevated temperatures in low-Cr ferritic steels in use as structural materials in nuclear energy applications.

    Ladda ner fulltext (pdf)
    fulltext
  • 3.
    Xu, Liubin
    et al.
    Univ Tennessee, TN 37996 USA.
    Casillas Trujillo, Luis
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Univ Tennessee, TN 37996 USA.
    Gao, Yanfei
    Univ Tennessee, TN 37996 USA.
    Xu, Haixuan
    Univ Tennessee, TN 37996 USA.
    Compositional effects on stacking fault energies in Ni-based alloys using first-principles and atomistic simulations2021Ingår i: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 197, artikel-id 110618Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Stacking fault energy (SFE) in fcc materials is a fundamental property that is closely related to Shockley partial dislocations and deformation twinning, the latter of which is potentially responsible for some of the exceptional mechanical properties observed in Ni-based high/medium-entropy alloys. In this study, the SFEs and twinning energies over a wide range of compositions are systematically determined in model Ni-based binary alloys using both first-principles density functional theory (DFT) and atomistic simulations with interatomic potentials. Particularly, different compositional dependences of SFEs are observed in the selected binary alloys (Ni-Cu, NiCo, and Ni-Fe) from DFT calculations. We find that SFEs of Ni-Co follow a linear-mixing rule while Ni-Cu and NiFe systems exhibit non-linear compositional dependences, especially in the concentrated region towards the center of the phase diagram. Analyses of the magnetic structures help clarify the origins of the non-linear dependences. The fidelity of existing interatomic potentials for these alloys is evaluated against DFT. Using the interatomic potentials with the overall highest fidelity, the SFE calculations are extended to Cantor-related ternary alloys (Ni-Co-Cr and Ni-Co-Fe) and the spatial features of the fault energies in atomistic simulations are also discussed. These results provide the basis for a systematic understanding of the compositional effects on the SFEs and twinning energies, which could be useful for a systematic tuning of mechanical properties in nonequimolar alloys, thus leading to a broad field in alloy design.

  • 4.
    Casillas Trujillo, Luis
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Osinger, Barbara
    Uppsala Univ, Sweden.
    Lindblad, Rebecka
    Uppsala Univ, Sweden.
    Karlsson, Dennis
    Uppsala Univ, Sweden.
    Abrikossov, Alexei
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Fritze, Stefan
    Uppsala Univ, Sweden.
    von Fieandt, Kristina
    Uppsala Univ, Sweden.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Hotz, Ingrid
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Jansson, Ulf
    Uppsala Univ, Sweden.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Natl Univ Sci & Technol MISIS, Russia.
    Lewin, Erik
    Uppsala Univ, Sweden.
    Experimental and theoretical evidence of charge transfer in multi-component alloys - how chemical interactions reduce atomic size mismatch2021Ingår i: Materials Chemistry Frontiers, E-ISSN 2052-1537, Vol. 5, nr 15, s. 5746-5759Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ab initio simulations of a multi-component alloy using density functional theory (DFT) were combined with experiments on thin films of the same material using X-ray photoelectron spectroscopy (XPS) to study the connection between the electronic and atomic structures of multi-component alloys. The DFT simulations were performed on an equimolar HfNbTiVZr multi-component alloy. Structure and charge transfer were evaluated using relaxed, non-relaxed, as well as elemental reference structures. The use of a fixed sphere size model allowed quantification of charge transfer, and separation into different contributions. The charge transfer was generally found to follow electronegativity trends and results in a reduced size mismatch between the elements, and thus causes a considerable reduction of the lattice distortions compared to a traditional assumption based on tabulated atomic radii. A calculation of the average deviation from the average radius (i.e. the so-called delta-parameter) based on the atomic Voronoi volumes gave a reduction of delta from ca. 6% (using the volumes in elemental reference phases) to ca. 2% (using the volumes in the relaxed multi-component alloy phase). The reliability of the theoretical results was confirmed by XPS measurements of a Hf22Nb19Ti18V19Zr21 thin film deposited by sputter deposition. The experimentally observed core level binding energy shifts (CLS), as well as peak broadening due to a range of chemical surroundings, for each element showed good agreement with the calculated DFT values. The single solid solution phase of the sample was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) including energy dispersive spectroscopy (EDS) with nm-resolution. These observations show that the HfNbTiVZr solid solution phase is non-ideal, and that chemical bonding plays an important part in the structure formation, and presumably also in the properties. Our conclusions should be transferable to other multi-component alloy systems, as well as some other multi-component material systems, and open up interesting possibilities for the design of material properties via the electronic structure and controlled charge transfer between selected metallic elements in the materials.

    Ladda ner fulltext (pdf)
    fulltext
  • 5.
    Casillas Trujillo, Luis
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Armiento, Rickard
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Identification of materials with strong magnetostructural coupling using computational high-throughput screening2021Ingår i: Physical Review Materials, E-ISSN 2475-9953, Vol. 5, nr 3, artikel-id 034417Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Important phenomena such as magnetostriction, magnetocaloric, and magnetoelectric effects arise from, or could be enhanced by, the coupling of magnetic and structural degrees of freedom. The coupling of spin and lattice also influence transport and structural properties in magnetic materials, in particular around phase transitions. In this paper we propose a method for screening materials for a strong magnetostructural coupling by assessing the effect of the local magnetic configuration on the atomic forces using density functional theory. We have employed the disordered local moment approach in a supercell formulation to probe different magnetic local configurations and their forces and performed a high-throughput search on binary and ternary compounds available in the Crystallography Open Database. We identify a list of materials with a strong spin-lattice coupling out of which several are already known to display magnetolattice coupling phenomena such as Fe3O4 and CrN. Others, such as Mn2CrO4 and CaFe7O11, have been less studied and have yet to reveal their potentials in experiments and applications.

  • 6.
    Baldinozzi, Gianguido
    et al.
    Univ Paris Saclay, France.
    Casillas Trujillo, Luis
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Patel, Maulik K.
    Univ Liverpool, England.
    Sickafus, Kurt E.
    Univ Tennessee, TN 37996 USA.
    Structural complexity of Y6BO12 fluorite-related ternary oxides2021Ingår i: MRS Advances, E-ISSN 2059-8521, Vol. 6, nr 4-5, s. 107-111Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Oxides with generic stoichiometry M7O12 occupy, in a generic phase diagram, an intermediate place between fluorite and bixbyite structure types. Their structure is derived from the ideal fluorite structure, and it is characterized by a more or less pronounced ordering of the O vacancies within the average fluorite sublattice. We believe that ternary oxides with this kind of formula provide interesting degrees of flexibility for understanding the structural characteristic of these structures in the context of fission product stabilization in nuclear fuels and in the field of actinide waste forms as well. We would like to discuss the structural characteristics of the chemical bonds in ternary systems consisting of trivalent and hexavalent cations. Eventually, in compounds with generic formula Y6B+6O12, the B cation can be either a transition metal (W, Mo) or hexavalent uranium. We believe that studying the polyhedron of the sevenfold coordinated Y ion is particularly interesting to understand the flexibility of the chemical bonds: it is often described in the literature as a mono-capped trigonal prism, with bond lengths exhibiting an extremely large dispersion, ranging for instance from 2.19 to 2.70 angstrom in Y6WO12. We would discuss the implications of this large dispersion of distances on the chemical bond characteristics and compare DFT models with established experimental knowledge on pristine and irradiated specimens. Graphic abstract

  • 7.
    Casillas Trujillo, Luis
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Configurational thermodynamics of a 1/2111 screw dislocation core in Mo-W solid solutions using cluster expansion2020Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 128, nr 4, artikel-id 045114Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, we have developed a methodology to obtain an ab initio cluster expansion of a system containing a dislocation and studied the effect of configurational disorder on the 1/2111 screw dislocation core structure in disordered Mo1-xWx alloys. Dislocation cores control the selection of glide planes, cross slip, and dislocation nucleation. Configurational disorders in alloys can impact the dislocation core structure and affect dislocation mobility. For our calculations, we have used a quadrupolar periodic array of screw dislocation dipoles and obtained the relaxed structures and energies using density functional theory. We have obtained the dislocation core structure as a function of composition and the interaction energies of solutes with the dislocation as a function of position with respect to the core. With these energies, we performed mean-field calculations to assess segregation toward the core. Finally, with the calculated energies of 1848 alloy configurations with different compositions, we performed a first principle cluster expansion of the configurational energetics of Mo1-xWx solid solutions containing dislocations.

    Ladda ner fulltext (pdf)
    fulltext
  • 8.
    Casillas Trujillo, Luis
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Jansson, Ulf
    Uppsala Univ, Sweden.
    Sahlberg, Martin
    Uppsala Univ, Sweden.
    Ek, Gustav
    Uppsala Univ, Sweden.
    Nygard, Magnus M.
    Inst Energy Technol, Norway.
    Sorby, Magnus H.
    Inst Energy Technol, Norway.
    Hauback, Bjorn C.
    Inst Energy Technol, Norway.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Natl Univ Sci & Technol MISIS, Russia.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Interstitial carbon in bcc HfNbTiVZr high-entropy alloy from first principles2020Ingår i: Physical Review Materials, E-ISSN 2475-9953, Vol. 4, nr 12, artikel-id 123601Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The remarkable mechanical properties of high-entropy alloys can be further improved by interstitial alloying. In this work we employ density functional theory calculations to study the solution energies of dilute carbon interstitial atoms in tetrahedral and octahedral sites in bcc HfNbTiVZr. Our results indicate that carbon interstitials in tetrahedral sites are unstable, and the preferred octahedral sites present a large spread in the energy of solution. The inclusion of carbon interstitials induces large structural relaxations with long-range effects. The effect of local chemical environment on the energy of solution is investigated by performing a local cluster expansion including studies of its correlation with the carbon atomic Voronoi volume. However, the spread in solution energetics cannot be explained with a local environment analysis only pointing towards a complex, long-range influence of interstitial carbon in this alloy.

    Ladda ner fulltext (pdf)
    fulltext
  • 9.
    Casillas Trujillo, Luis
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Gambino, Davide
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Ventelon, Lisa
    Univ Paris Saclay, France.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Screw dislocation core structure in the paramagnetic state of bcc iron from first-principles calculations2020Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 102, nr 9, artikel-id 094420Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Iron-based alloys are widely used as structural components in engineering applications. This calls for a fundamental understanding of their mechanical properties, including those of pure iron. Under operational temperatures the mechanical and magnetic properties will differ from those of ferromagnetic body-centered-cubic iron at 0 K. In this theoretical work we study the effect of disordered magnetism on the screw dislocation core structure and compare with results for the ordered ferromagnetic case. Dislocation cores control some local properties such as the choice of glide plane and the associated dislocation mobility. Changes in the magnetic state can lead to modifications in the structure of the core and affect dislocation mobility. In particular, we focus on the core properties of the 1/2 &lt; 111 &gt; screw dislocation in the paramagnetic state. Using the noncollinear disordered local moment approximation to address paramagnetism, we perform structural relaxations within density functional theory. We obtain the dislocation core structure for the easy and hard cores in the paramagnetic state, and compare them with their ferromagnetic counterparts. By averaging the energy of several disordered magnetic configurations, we obtain an energy difference between the easy- and hard-core configurations, with a lower, but statistically close, value than the one reported for the ferromagnetic case. The magnetic moment and atomic volume at the dislocation core differ between paramagnetic and ferromagnetic states, with possible consequences on the temperature dependence of defect-dislocation interactions.

    Ladda ner fulltext (pdf)
    fulltext
1 - 9 av 9
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf