• Approaching the Limits of Aspect Ratio in Free-Standing Al2O3 3D Shell Structures 

      Burgmann, Stephanie; Lid, Markus Joakim; Chaikasetsin, Settasit; Bjørdal, Dag Skjerven; Prinz, Fritz; Provine, John; Berto, Filippo; Van Helvoort, Antonius; Torgersen, Jan (Peer reviewed; Journal article, 2022)
      Nanoscale free-standing membranes are used for a variety of sensors and other micro/nano-electro-mechanical systems devices. To tune performance, it is indispensable to understand the limits of aspect ratios achievable. ...
    • Atomic resolution imaging of beryl: an investigation of the nano-channel occupation 

      Van Helvoort, Antonius; Holst, Bodil; Schmitz, F.D.; Arivazhagan, V.; Vullum, Per Erik (Journal article; Peer reviewed, 2016)
      Beryl in different varieties (emerald, aquamarine, heliodor etc.) displays a wide range of colours that have fascinated humans throughout history. Beryl is a hexagonal cyclo-silicate (ring-silicate) with channels going ...
    • Atomic-scale 3D imaging of individual dopant atoms in an oxide semiconductor 

      Hunnestad, Kasper Aas; Hatzoglou, Constantinos; Zeeshan, Muhammad; Vullum, Per Erik; Yan, Zewu; Bourret, Edith; Van Helvoort, Antonius; Selbach, Sverre Magnus; Meier, Dennis (Peer reviewed; Journal article, 2022)
      The physical properties of semiconductors are controlled by chemical doping. In oxide semiconductors, small variations in the density of dopant atoms can completely change the local electric and magnetic responses caused ...
    • Composition Analysis by STEM-EDX of Ternary Semiconductors by Internal References 

      Nilsen, Julie Stene; Van Helvoort, Antonius (Peer reviewed; Journal article, 2021)
      A practical method to determine the composition within ternary heterostructured semiconductor compounds using energy-dispersive X-ray spectroscopy in scanning transmission electron microscopy is presented. The method ...
    • Conductivity control via minimally invasive anti-Frenkel defects in a functional oxide 

      Evans, Donald; Holstad, Theodor Secanell; Mosberg, Aleksander Buseth; Småbråten, Didrik Rene; Vullum, Per Erik; Dadlani, Anup; Shapovalov, Konstantin; Yan, Zewu; Bourret, Edith; Gao, David Zhe; Akola, Jaakko; Torgersen, Jan; Van Helvoort, Antonius; Selbach, Sverre Magnus; Meier, Dennis (Peer reviewed; Journal article, 2020)
      Utilizing quantum effects in complex oxides, such as magnetism, multiferroicity and superconductivity, requires atomic-level control of the material’s structure and composition. In contrast, the continuous conductivity ...
    • Contact-free reversible switching of improper ferroelectric domains by electron and ion irradiation 

      Roede, Erik Dobloug; Mosberg, Aleksander Buseth; Evans, Donald; Bourret, Edith; Yan, Zewu; Van Helvoort, Antonius; Meier, Dennis (Peer reviewed; Journal article, 2021)
      Focused ion beam (FIB) and scanning electron microscopy (SEM) are used to reversibly switch improper ferroelectric domains in the hexagonal manganite ErMnO3. Surface charging is achieved by local ion (positive charging) ...
    • Correlated subgrain and particle analysis of a recovered Al-Mn alloy by directly combining EBSD and backscatter electron imaging 

      Ånes, Håkon Wiik; Van Helvoort, Antonius; Marthinsen, Knut (Journal article, 2022)
      Correlated analysis of (sub)grains and particles in alloys is important to understand transformation processes and control material properties. A multimodal data fusion workflow directly combining subgrain data from electron ...
    • Correlating laser energy with compositional and atomic-level information of oxides in atom probe tomography 

      Hunnestad, Kasper Aas; Hatzoglou, hatzoglou; Vurpillot, F.; Nylund, Inger-Emma; Yan, Z.; Bourret, E.; Van Helvoort, Antonius; Meier, Dennis (Peer reviewed; Journal article, 2023)
      Atom probe tomography (APT) is a 3D analysis technique that offers unique chemical accuracy and sensitivity with sub-nanometer spatial resolution. There is an increasing interest in the application of APT to complex oxides ...
    • Crystal Phase Mapping by Scanning Precession Electron Diffraction and Machine Learning Decomposition 

      Ånes, Håkon Wiik; Andersen, Ingrid Marie; Van Helvoort, Antonius (Journal article; Peer reviewed, 2018)
      Analyzing the distribution of crystal phases is required to understand nanostructures. Conventional analysis in the transmission electron microscope (TEM) include acquiring dark-field (DF) images for each expected crystal ...
    • Crystallographic relationships of T-/S-phase aggregates in an Al–Cu–Mg–Ag alloy 

      Sunde, Jonas Kristoffer; Johnstone, D.N.; Wenner, Sigurd; Van Helvoort, Antonius; Midgley, Paul A.; Holmestad, Randi (Journal article; Peer reviewed, 2018)
      T-(Al20Cu2Mn3) phase dispersoids are important for limiting recovery and controlling grain growth in Al-Cu alloys. However, these dispersoids can also reduce precipitation hardening by acting as heterogeneous nucleation ...
    • Determination of GaAs zinc blende/wurtzite band offsets utilizing GaAs nanowires with an axial GaAsSb insert 

      Ahtapodov, Lyubomir; Kauko, H; Munshi, A Mazid; Fimland, Bjørn-Ove; Van Helvoort, Antonius; Weman, Helge (Journal article; Peer reviewed, 2017)
      By applying a correlated micro-photoluminescence spectroscopy and transmission electron microscopy (TEM) approach, we have utilized molecular beam epitaxy grown self-catalysed GaAs nanowires (NWs) with an axial GaAsSb ...
    • Effect of the nanostructuring by high-pressure torsion process on the secondary phase precipitation in UNS S32750 Superduplex stainless steel 

      Biserova-Tahchieva, A; Chatterjee, Dipanwita; Van Helvoort, Antonius; Llorca-Isern, N; Cabrera, J. M. (Journal article; Peer reviewed, 2021)
    • Epitaxially grown III-arsenide-antimonide nanowires for optoelectronic applications 

      Ren, Dingding; Ahtapodov, Lyubomir; Van Helvoort, Antonius; Weman, Helge; Fimland, Bjørn-Ove (Journal article; Peer reviewed, 2019)
      Epitaxially grown ternary III-arsenide-antimonide (III-As–Sb) nanowires (NWs) are increasingly attracting attention due to their feasibility as a platform for the integration of largely lattice-mismatched antimonide-based ...
    • FIB lift-out of conducting ferroelectric domain walls in hexagonal manganites 

      Mosberg, Aleksander Buseth; Roede, Erik Dobloug; Evans, Donald; Holstad, Theodor S.; Bourret, Edith; Yan, Zewu; Van Helvoort, Antonius; Meier, Dennis (Journal article; Peer reviewed, 2019)
      A focused ion beam (FIB) methodology is developed to lift out suitable specimens containing charged domain walls in improper ferroelectric ErMnO3. The FIB procedure allows for extracting domain wall sections with well-defined ...
    • FIB lift-out of conducting ferroelectric domain walls in hexagonal manganites 

      Evans, Donald; Meier, Dennis; Mosberg, Aleksander Buseth; Roede, Erik Dobloug; Holstad, Theodor S.; Bourret, Edith; Yan, Zewu; Van Helvoort, Antonius (Journal article; Peer reviewed, 2019)
      A focused ion beam (FIB) methodology is developed to lift out suitable specimens containing charged domain walls in improper ferroelectric ErMnO3. The FIB procedure allows for extracting domain wall sections with well-defined ...
    • Growth study of self-assembled GaN nanocolumns on silica glass by plasma assisted molecular beam epitaxy 

      Liudi Mulyo, Andreas; Konno, Yuta; Nilsen, Julie Stene; Van Helvoort, Antonius; Fimland, Bjørn-Ove; Weman, Helge; Kishino, Katsumi (Journal article; Peer reviewed, 2017)
      We demonstrate GaN nanocolumn growth on fused silica glass by plasma-assisted molecular beam epitaxy. The effect of the substrate temperature, Ga flux and N2 flow rate on the structural and optical properties are studied. ...
    • High resolution crystal orientation mapping of ultrathin films in SEM and TEM 

      Heinig, M. F.; Chatterjee, Dipanwita; Van Helvoort, Antonius; Wagner, Jakob B.; Kadkhodazadeh, S; Ånes, Håkon Wiik; Niessen, F; Bastos da Silva, A. (Peer reviewed; Journal article, 2022)
      Ultrathin metallic films are important functional materials for optical and microelectronic devices. Dedicated characterization with high spatial resolution and sufficient field of view is key to the understanding of the ...
    • Image Processing of 2-D Snow Images for Cross-Country Skiing 

      Rosenberg, Fredrik (Master thesis, 2020)
      Snø er et porøst og komplekst materiale med innflytelse på både vitenskapelige, teknologiske og sosiale arenaer. Dette gjør analyse av snø til en viktig, men krevende oppgave. Tredimensjonal snø analyse gir nøyaktig ...
    • In-situ observations of dislocation recovery and low angle boundary formation in deformed aluminium 

      Ånes, Håkon Wiik; Van Helvoort, Antonius; Marthinsen, Knut (Journal article; Peer reviewed, 2019)
      An experimental study of the recovery of dislocations and low angle boundary formation in aluminium is presented. By combining in-situ annealing with orientation mapping in the transmission electron microscope, maps of ...
    • Nanocrystal segmentation in scanning precession electron diffraction data 

      Bergh, Tina; Johnstone, D.N.; Crout, P; Høgås, Simon; Midgley, Paul A.; Holmestad, Randi; Vullum, Per Erik; Van Helvoort, Antonius (Journal article; Peer reviewed, 2019)
      Scanning precession electron diffraction (SPED) enables the local crystallography of materials to be probed on the nanoscale by recording a two‐dimensional precession electron diffraction (PED) pattern at every probe ...