Browsing NTNU Open by Author "Vullum, Per Erik"

Now showing items 1-20 of 75

    • 3D aligned-carbon-nanotubes@Li2FeSiO4 arrays as high rate capability cathodes for Li-ion batteries 

      Zhou, Haitao; Lou, Fengliu; Vullum, Per Erik; Einarsrud, Mari-Ann; Chen, De; Vullum-Bruer, Fride (Journal article; Peer reviewed, 2013-09-27)
      3D aligned-carbon-nanotubes (ACNTs)@Li2FeSiO4 nanocomposite arrays on Al foil were developed as cathode materials for Li-ion batteries. The ACNTs were grown directly on an Al foil by a chemical vapor deposition method to ...

    • Atomap - Automated Analysis of Atomic Resolution STEM Images 

      Nord, Magnus Kristofer; Vullum, Per Erik; MacLaren, I; Tybell, Per Thomas Martin; Holmestad, Randi (Journal article, 2017)
      Atomic resolution scanning transmission electron microscopy (STEM) data contain a large amount of information about the structure of a crystalline material. Often, this information is hard to extract, due to the large ...

    • Atomap: a new software tool for the automated analysis of atomic resolution images using two-dimensional Gaussian fitting 

      Nord, Magnus Kristofer; Vullum, Per Erik; MacLaren, Ian; Tybell, Per Thomas Martin; Holmestad, Randi (Journal article; Peer reviewed, 2017)
      Scanning transmission electron microscopy (STEM) data with atomic resolution can contain a large amount of information about the structure of a crystalline material. Often, this information is hard to extract, due to the ...

    • 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 ...

    • Bandgap measurement of high refractive index materials by off-axis EELS 

      Vatanparast, Maryam; Egoavil, Ricardo; Reenaas, Turid Worren; verbeeck, Johan; Holmestad, Randi; Vullum, Per Erik (Journal article; Peer reviewed, 2017)
      In the present work Cs aberration corrected and monochromated scanning transmission electron microscopy electron energy loss spectroscopy (STEM-EELS) has been used to explore experimental set-ups that allow bandgaps of ...

    • Bottom-Up Fabrication of Oxygen Reduction Electrodes with Atomic Layer Deposition for High-Power-Density PEMFCs 

      Dull, Sam; Xu, Shicheng; Goh, Timothy; Lee, Dong Un; Higgins, Drew; Orazov, Marat; Koshy, David; Vullum, Per Erik; Kirsch, Sebastian; Huebner, Gerold; Torgersen, Jan; Jaramillo, Thomas F; Prinz, Friedrich (Journal article, 2021)
      As the platinum (Pt) loading in proton exchange membrane fuel cell cathodes is driven down to reduce costs, catalyst utilization becomes increasingly important. Here, we report an atomic layer deposition-facilitated electrode ...

    • Broadband infrared and THz transmitting silicon core optical fiber 

      Sørgård, Trygve; Song, Seunghan; Vullum, Per Erik; Kores, Cristine; Mølster, Kjell Martin; Laurell, Fredrik; Hawkins, Thomas A.; Ballato, John; Österberg, Ulf Lennart; Gibson, Ursula (Peer reviewed; Journal article, 2020)
      Silicon waveguide structures are a viable alternative for the transmission of signals over a wide range of frequencies, and new fabrication methods are key to increased applications. In this work, THz transparency of ...

    • Bulk substitution of F-terminations from Ti3C2Tx MXene by cation pillaring and gas hydrolysation 

      Fagerli, Frode Håskjold; Vullum, Per Erik; Grande, Tor; Wang, Zhaohui; Selbach, Sverre Magnus; Wiik, Kjell; Wagner, Nils Peter (Journal article, 2023)
      Applications of 2D MXenes are limited by the difficulty of controlling bulk termination groups after the initial HF etching step without forming surface oxides. Here, we report on gas hydrolysation using a continuous flow ...

    • Cation Disorder in Ferroelectric Ba4M2Nb10O30 (M = Na, K, and Rb)Tetragonal Tungsten Bronzes 

      Nylund, Inger-Emma; Løndal, Nora Statle; Walker, Julian; Vullum, Per Erik; Einarsrud, Mari-Ann; Grande, Tor (Journal article; Peer reviewed, 2022)

    • Centrosymmetric Tetragonal Tungsten Bronzes A4Bi2Nb10O30 (A = 2 Na, K, Rb) with a Bi 6s Lone Pair 

      Nylund, Inger-Emma; Zeiger, Caren Regine; Peng, Ding; Vullum, Per Erik; Walker, Julian; Einarsrud, Mari-Ann; Grande, Tor (Peer reviewed; Journal article, 2022)
      A first-principles study of the tetragonal tungsten bronze (TTB) K4Bi2Nb10O30 has suggested that the Bi 6s lone pair causes in-plane polarization (within the a–b plane), corresponding to the one found in Pb5Nb10O30 (PN), ...

    • Characterization of BaTiO3/La0.7Sr0.3MnO3 Thin Films on SrTiO3(111) Substrates - A Transmission Electron Microscopy Study 

      Holstad, Theodor Secanell (Master thesis, 2016)
      In this work, an oxide thin film system was investigated by using transmission electron microscopy (TEM) techniques. It is of great interest to study such systems due to their current applications as well as potential ...

    • Cold welding of steel and aluminum alloys - Joining processes, intermetallic phases and bond strength 

      Arbo, Siri Marthe (Doctoral theses at NTNU;2020:16, Doctoral thesis, 2020)
      Steel and aluminum are two of the most commonly used metals in today’s society and can be found everywhere, in vehicles, buildings, ships, and in most new electronic devices to name a few. Both metals have desirable ...

    • Compositional and structural properties of pulsed laser-deposited ZnS:Cr films 

      Nematollahi, Mohammadreza; Yang, Xiaodong; Seim, Eivind; Vullum, Per Erik; Holmestad, Randi; Gibson, Ursula; Reenaas, Turid Worren (Journal article; Peer reviewed, 2016)
      We present the properties of Cr-doped zinc sulfide (ZnS:Cr) films deposited on Si(100) by pulsed laser deposition. The films are studied for solar cell applications, and to obtain a high absorption, a high Cr content ...

    • 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 ...

    • Continental weathering and recovery from ocean nutrient stress during the Early Triassic Biotic Crisis 

      Knies, Jochen Manfred; Schönenberger, Jasmin; Zwingmann, Horst; van der Lelij, Roelant; Smelror, Morten; Vullum, Per Erik; Vogt, Christoph; Fredin, Ola; Muller, Alxel; Grasby, Stephen E.; Beauchamp, Benoit; Viola, Giulio (Peer reviewed; Journal article, 2022)
      Following the latest Permian extinction ∼252 million years ago, normal marine and terrestrial ecosystems did not recover for another 5-9 million years. The driver(s) for the Early Triassic biotic crisis, marked by high ...

    • Critically testing olivine-hosted putative martian biosignatures in the Yamato 000593 meteorite - Geobiological implications 

      McLoughlin, Nicola; Grosch, Eugene Gerald; Vullum, Per Erik; Guagliardo, Paul; Saunders, Martin; Wacey, David (Journal article; Peer reviewed, 2019)
      On rocky planets such as Earth and Mars the serpentinization of olivine in ultramafic crust produces hydrogen that can act as a potential energy source for life. Direct evidence of fluid–rock interaction on Mars comes from ...

    • Detecting minute amounts of nitrogen in GaNAs thin films using STEM and CBED 

      Vatanparast, Maryam; Shao, Yu-Tsun; Rajpalke, Mohana; Fimland, Bjørn-Ove; Reenaas, Turid Dory; Holmestad, Randi; Vullum, Per Erik; Zuo, Jian Min (Journal article; Peer reviewed, 2021)
      Nitrogen (N) is a common element added to GaAs for band gap engineering and strain compensation. However, detection of small amounts of N is difficult for electron microscopy as well as for other chemical analysis techniques. ...

    • Direct Integration of Strained-Pt Catalysts into Proton-Exchange-Membrane Fuel Cells with Atomic Layer Deposition 

      Xu, Shicheng; Wang, Zhaoxuan; Dull, Sam; Liu, Yunzhi; Lee, Dong Un; Pacheco, Lezama; Orazov, Marat; Vullum, Per Erik; Dadlani, Anup; Vinogradova, Olga; Schindler, Peter; Tam, Qizhan; Schladt, Thomas; Mueller, Jonathan E.; Kirsch, Sebastian; Huebner, Gerold; Higgins, Drew; Torgersen, Jan; Viswanathan, Venkatasubramanian; Jaramillo, Thomas F; Prinz, Friedrich (Peer reviewed; Journal article, 2021)
      The design and fabrication of lattice-strained platinum catalysts achieved by removing a soluble core from a platinum shell synthesized via atomic layer deposition, is reported. The remarkable catalytic performance for the ...

    • The effect of addition of the redox mediator dimethylphenazine on the oxygen reaction in porous carbon electrodes for Li/O2 batteries 

      Vullum-Bruer, Fride; Vullum, Per Erik; Svensson, Ann Mari; Augustin, Matthias (Peer reviewed; Journal article, 2023)
      Secondary Li–O2 batteries are promising due to their potentially high theoretical energy density. However, both the discharge (oxygen reduction reaction, ORR) and the recharge reaction (oxygen evolution reaction, OER) are ...