Anette Eleonora Gunnæs

• de Ruiter, Lisa; Gunnæs, Anette Eleonora; Dysthe, Dag Kristian & Austrheim, Håkon Olaf (2021). Quartz dissolution associated with magnesium silicate hydrate cement precipitation. Solid Earth (SE). ISSN 1869-9510. 12(2), s. 389–404. doi: 10.5194/se-12-389-2021.
• Larsen, Aleksander; Poulia, Anthoula; S. Azar, Amin; Bazioti, Kalliopi; Almeida Carvalho, Patricia & Gunnæs, Anette Eleonora [Vis alle 9 forfattere av denne artikkelen] (2021). Identifying Magnetic Phases in Additively Manufactured High-Entropy Alloy FeCoNiAlxMnx, 2021 IEEE 10th International Conference on “Nanomaterials: Applications & Properties” (NAP – 2021). IEEE. ISSN 978-1-6654-3907-7. s. NMM03-1–NMM03-4. doi: 10.1109/NAP51885.2021.9568591. Fulltekst i vitenarkiv
• Poulia, Anthoula; S. Azar, Amin; Schrade, M.; Graff, J.S.; Bazioti, Kalliopi & Gunnæs, Anette Eleonora [Vis alle 8 forfattere av denne artikkelen] (2021). Process–Structure–Property Relationship in FeCoNiAlxMnx Complex Concentrated Alloys Processed by Additive Manufacturing. Journal of materials engineering and performance (Print). ISSN 1059-9495. doi: 10.1007/s11665-021-06082-8.
• Poulia, Anthoula; S. Azar, Amin; Svec, Peter; Bazioti, Kalliopi; Belle, Branson & Gunnæs, Anette Eleonora [Vis alle 8 forfattere av denne artikkelen] (2020). Nanoscale Magnetic Properties of Additively Manufactured FeCoNiAlxMnx High-Entropy Alloys, 2020 IEEE 10th International Conference on “Nanomaterials: Applications & Properties” (NAP – 2020). IEEE. ISSN 978-1-7281-8506-4. s. 01NMM02-1–01NMM02-5. doi: 10.1109/NAP51477.2020.9309571. Fulltekst i vitenarkiv
• Kalyva, Maria Evangelou; Sunding, Martin Fleissner; Gunnæs, Anette Eleonora; Diplas, Spyridon & Redekop, Evgeniy (2020). Correlation between surface chemistry and morphology of PtCu and Pt nanoparticles during oxidation-reduction cycle. Applied Surface Science. ISSN 0169-4332. 532, s. 1–6. doi: 10.1016/j.apsusc.2020.147369. Fulltekst i vitenarkiv
• Gutterød, Emil Sebastian; Pulumati, S.H.; Kaur, Gurpreet; Lazzarini, Andrea; Solemsli, Bjørn Garding & Gunnæs, Anette Eleonora [Vis alle 13 forfattere av denne artikkelen] (2020). Influence of Defects and H2O on the Hydrogenation of CO2 to Methanol over Pt Nanoparticles in UiO-67 Metal-Organic Framework. Journal of the American Chemical Society. ISSN 0002-7863. 142(40), s. 17105–17118. doi: 10.1021/jacs.0c07153. Fulltekst i vitenarkiv
• Wachowski, Sebastian Lech; Szpunar, Iga; Sørby, Magnus Helgerud; Mielewczyk-Gryń, Aleksandra; Balaguer, Maria & Ghica, Corneliu [Vis alle 12 forfattere av denne artikkelen] (2020). Structure and water uptake in BaLnCo2O6−δ (Ln = La, Pr, Nd, Sm, Gd, Tb and Dy). Acta Materialia. ISSN 1359-6454. 199, s. 297–310. doi: 10.1016/j.actamat.2020.08.018. Fulltekst i vitenarkiv
• Gunnæs, Anette Eleonora; Tofan, Raluca; Berland, Kristian; Gorantla, Sandeep Madhukar; Storaas, Thomas Aarflot & Desissa, Temesgen Debelo [Vis alle 12 forfattere av denne artikkelen] (2020). Chemical stability of Ca3Co4−xO9+δ/CaMnO3−δ p–n junction for oxide-based thermoelectric generators. RSC Advances. ISSN 2046-2069. 10(9), s. 5026–5031. doi: 10.1039/c9ra07159h. Fulltekst i vitenarkiv
• Molino, Andrea; Holzinger, J.; Lukaszuk, Katarzyna Anna; Rojo-Gama, Daniel; Gunnæs, Anette Eleonora & Skibsted, J. [Vis alle 11 forfattere av denne artikkelen] (2019). Synthesis of ZSM-23 (MTT) zeolites with differentcrystal morphology and intergrowths: effects onthe catalytic performance in the conversion ofmethanol to hydrocarbons. Catalysis Science & Technology. ISSN 2044-4753. 9(23), s. 6782–6792. doi: 10.1039/c9cy01068h. Fulltekst i vitenarkiv
• Oyama, Kohei; Diplas, Spyridon; M'hamdi, Mohammed; Gunnæs, Anette Eleonora & S. Azar, Amin (2019). Heat source management in wire-arc additive manufacturing process for Al-Mg and Al-Si alloys. Additive Manufacturing. ISSN 2214-8604. 26, s. 180–192. doi: 10.1016/j.addma.2019.01.007. Fulltekst i vitenarkiv
• Guzik, Matylda N.; Schrade, Matthias; Tofan, Raluca; Almeida Carvalho, Patricia; Berland, Kristian & Sørby, Magnus Helgerud [Vis alle 9 forfattere av denne artikkelen] (2019). Long- and short-range structures of Ti1-xHfxNi1.0/1.1Sn half-Heusler compounds and their electric transport properties. CrysteEngComm. ISSN 1466-8033. 21, s. 3330–3342. doi: 10.1039/c9ce00046a. Fulltekst i vitenarkiv
• Hjelmeland, Trude Bjørgås; Bazioti, Kalliopi; Gunnæs, Anette Eleonora; Volkov, Y & Mikheenko, Pavlo (2019). Effect of colossal magnetoresistance material La0.67Ca0.33MnO3 on superconducting properties of YBa2Cu3O7-δ thin films. Journal of Magnetism and Magnetic Materials. ISSN 0304-8853. 487. doi: 10.1016/j.jmmm.2019.165335. Fulltekst i vitenarkiv
• Bundli, Silje; Dhak, Prasanta; Jensen, Martin; Gunnæs, Anette Eleonora; Nguyen, Phuong Dan & Fjellvåg, Helmer [Vis alle 7 forfattere av denne artikkelen] (2019). Controlled alloying of Pt-Rh nanoparticles by the polyol approach. Journal of Alloys and Compounds. ISSN 0925-8388. 779, s. 879–885. doi: 10.1016/j.jallcom.2018.11.301.
• Guzik, Matylda N.; Echevarria-Bonet, Cristina; Riktor, Marit Dalseth; Almeida Carvalho, Patricia; Gunnæs, Anette Eleonora & Sørby, Magnus Helgerud [Vis alle 7 forfattere av denne artikkelen] (2018). Half-Heusler phase formation and Ni atom distribution in M-Ni-Sn (M = Hf, Ti, Zr) systems. Acta Materialia. ISSN 1359-6454. 148, s. 216–224. doi: 10.1016/j.actamat.2018.01.019. Fulltekst i vitenarkiv
• Bergum, Kristin; Riise, Heine Nygard; Gorantla, Sandeep Madhukar; Lindberg, Per; Jensen, Ingvild Julie Thue & Gunnæs, Anette Eleonora [Vis alle 10 forfattere av denne artikkelen] (2018). Improving carrier transport in Cu2O thin films by rapid thermal annealing. Journal of Physics: Condensed Matter. ISSN 0953-8984. 30(7). doi: 10.1088/1361-648X/aaa5f4.
• Jensen, Ingvild Julie Thue; Gorantla, Sandeep Madhukar; Løvvik, Ole Martin; Gan, Jiantuo; Nguyen, Phuong Dan & Monakhov, Edouard [Vis alle 9 forfattere av denne artikkelen] (2017). Interface phenomena in magnetron sputtered Cu2O/ZnO heterostructures. Journal of Physics: Condensed Matter. ISSN 0953-8984. 29(43). doi: 10.1088/1361-648X/aa8799. Fulltekst i vitenarkiv
• Schrade, Matthias; Berland, Kristian; Eliassen, Simen Nut Hansen; Guzik, Matylda Natalia; Echevarria-Bonet, Cristina & Sørby, Magnus Helgerud [Vis alle 13 forfattere av denne artikkelen] (2017). The role of grain boundary scattering in reducing the thermal conductivity of polycrystalline XNiSn (X=Hf, Zr, Ti) half-Heusler alloys. Scientific Reports. ISSN 2045-2322. 7. doi: 10.1038/s41598-017-14013-8. Fulltekst i vitenarkiv
• Lindberg, Per Filip; Gorantla, Sandeep Madhukar; Gunnæs, Anette Eleonora; Svensson, Bengt Gunnar & Monakhov, Edouard (2017). Electronic properties and morphology of copper oxide/n-type silicon heterostructures. Journal of Physics: Condensed Matter. ISSN 0953-8984. 29(31). doi: 10.1088/1361-648X/aa77bc.
• Gan, Jiantuo; Gorantla, Sandeep Madhukar; Riise, Heine Nygard; Fjellvåg, Øystein Slagtern; Diplas, Spyridon & Løvvik, Ole Martin [Vis alle 9 forfattere av denne artikkelen] (2016). Structural properties of Cu2O epitaxial films grown on c-axis single crystal ZnO by magnetron sputtering. Applied Physics Letters. ISSN 0003-6951. 108:152110(15), s. 1–5. doi: 10.1063/1.4945985. Vis sammendrag

  Epitaxial Cu2O films grown by reactive and ceramic radio frequency magnetron sputtering on single crystalline ZnO (0001) substrates are investigated. The films are grown on both O- and Zn-polar surface of the ZnO substrates. The Cu2O films exhibit a columnar growth manner apart from a ∼5 nm thick CuO interfacial layer. In comparison to the reactively sputtered Cu2O, the ceramic-sputtered films are less strained and appear to contain nanovoids. Irrespective of polarity, the Cu2O grown by reactive sputtering is observed to have (111)Cu2O||(0001)ZnO epitaxial relationship, but in the case of ceramic sputtering the films are found to show additional (110)Cu2O reflections when grown on O-polar surface. The observed CuO interfacial layer can be detrimental for the performance of Cu2O/ZnO heterojunction solar cells reported in the literature.

• Gunnæs, Anette Eleonora; Gorantla, Sandeep Madhukar; Løvvik, Ole Martin; Gan, Jiantuo; Carvalho, Patricia & Svensson, Bengt Gunnar [Vis alle 10 forfattere av denne artikkelen] (2016). Epitaxial strain-induced growth of CuO at Cu2O/ZnO interfaces. Journal of Physical Chemistry C. ISSN 1932-7447. 120(41), s. 23552–23558. doi: 10.1021/acs.jpcc.6b07197. Vis sammendrag

  Cu2O/ZnO has been envisaged as a potential material system for the next generation thin film solar cells. So far, the experimental efforts to obtain conversion efficiencies close to the theoretically predicted value have failed. Combining aberration-corrected (scanning) transmission electron microscopy and density functional theory modelling, we have studied the interfaces between single crystal c-axis oriented ZnO and high-quality magnetron sputtered Cu2O films. Strikingly, our study shows that the first ~5 nm of the Cu-oxide films have the structure of the monoclinic CuO phase. The CuO layer is textured with the (111), (11¯1), (¯111), (1¯1 ¯1), (¯1 ¯11), (1¯11), (¯11¯1) and (100) planes parallel to the (0001) and (000¯1) ZnO interfaces. The ionic arrangement on these planes resembles the hexagonal arrangement of the ZnO interface and epitaxy exists across the interface. A continued epitaxial growth of [111] oriented Cu2O follows resulting in epitaxial 180o rotation twins in the Cu2O layer. For the case with the (100)CuO interfacial plane we have: (111)[1¯10]Cu2O II (100)[011]CuO II (0001)[11¯20]ZnO. Because of a closer lattice matching of CuO with ZnO and Cu2O, the total strain and energy is reduced compared to a pure (111)Cu2O II (0001)ZnO interface. The existence of CuO is anticipated to be a contributing factor for the low conversion efficiencies obtained experimentally.

• Song, Xin; Valset, Kjetil; Graff, Joachim Seland; Thøgersen, Annett; Gunnæs, Anette Eleonora & Luxsacumar, Sivakanesar [Vis alle 8 forfattere av denne artikkelen] (2015). Nanostructuring of undoped ZnSb by Cryo-Milling. Journal of Electronic Materials. ISSN 0361-5235. 44(8), s. 2578–2584. doi: 10.1007/s11664-015-3708-6. Vis sammendrag

  We report the preparation of nanosized ZnSb powder by cryo-milling. The effect of cryo-milling then hot-pressing of undoped ZnSb was investigated and compared with that of room temperature ball-milling and hot-pressing under different temperature conditions. ZnSb is a semiconductor with favorable thermoelectric properties when doped. We used undoped ZnSb to study the effect of nanostructuring on lattice thermal conductivity, and with little contribution at room temperature from electronic thermal conductivity. Grain growth was observed to occur during hot-pressing, as observed by transmission electron microscopy and x-ray diffraction. The thermal conductivity was lower for cryo-milled samples than for room-temperature ball-milled samples. The thermal conductivity also depended on hot-pressing conditions. The thermal conductivity could be varied by a factor of two by adjusting the process conditions and could be less than a third that of single-crystal ZnSb.

• Hage, Fredrik Sydow; Kepaptsoglou, Despoina Maria; Seabourne, Ché Royce; Ramasse, Quintim M.; Scott, Andrew J. & Prytz, Øystein [Vis alle 8 forfattere av denne artikkelen] (2014). Dielectric response of pentagonal defects in multilayer graphene nano-cones. Nanoscale. ISSN 2040-3364. 6(3), s. 1833–1839. doi: 10.1039/c3nr05419e.
• Nguyen, Phuong Dan; Gunnæs, Anette Eleonora; Sunding, Martin Fleissner & Olsen, Arne (2014). Heterogeneous nucleation and growth of CrSi2 in sputtered thin films of silicon/silicon nitride. Thin Solid Films. ISSN 0040-6090. 556, s. 200–205. doi: 10.1016/j.tsf.2014.01.080.
• Hage, Fredrik Sydow; Ramasse, Quentin; Kepaptsoglou, Despoina Maria; Prytz, Øystein; Gunnæs, Anette Eleonora & Helgesen, Geir [Vis alle 7 forfattere av denne artikkelen] (2013). Topologically induced confinement of collective modes in multilayer graphene nanocones measured by momentum-resolved STEM-VEELS. Physical Review B. Condensed Matter and Materials Physics. ISSN 1098-0121. 88(15). doi: 10.1103/PhysRevB.88.155408.
• Bleken, Bjørn Tore Lønstad; Wragg, David; Arstad, Bjørnar; Gunnæs, Anette Eleonora; Mouzon, Johanne & Helveg, Stig [Vis alle 12 forfattere av denne artikkelen] (2013). Unit cell thick nanosheets of zeolite H-ZSM-5: Structure and activity. Topics in catalysis. ISSN 1022-5528. 56(9-10), s. 558–566. doi: 10.1007/s11244-013-0010-9. Vis sammendrag

  Nanosheets of zeolite H-ZSM-5 were synthesized and characterized by X-ray diffraction, transmission electron microscopy (TEM), N2-physisorption, FT-IR spectroscopy, 27Al and 29Si MAS NMR spectroscopy in addition to catalytic testing in conversion of methanol to hydrocarbons (MTH). It was found that Rietveld analysis, involving anisotropic broadening parameters, gave average crystallite dimensions in good agreement with TEM images. The selectivities in MTH is intact in the mesoporous nanosheet H-ZSM-5 with the largest difference being a higher C3/C2 ratio compared to regular H-ZSM-5.

• Hadidi, Kianoosh; Hancke, Ragnhild; Norby, Truls; Løvvik, Ole Martin & Gunnæs, Anette Eleonora (2012). Atomistic study of LaNbO4; surface properties and hydrogen adsorption. International Journal of Hydrogen Energy. ISSN 0360-3199. 37(8), s. 6674–6685. doi: 10.1016/j.ijhydene.2012.01.065. Vis sammendrag

  We have calculated fundamental properties of pure and hydrogen-covered (010), (101), (100) and (001) surfaces of the low temperature monoclinic phase of LaNbO4 (LN). The (010) surface was the most stable one, exhibiting electronic structure and local geometric configurations similar to bulk. As the first stage of proton migration into the electrolyte, the ability of LN surfaces to split H2 molecules was probed indirectly by calculating the adsorption energy of H atoms on two of the LN surfaces. H adsorption on the (010) surface was found to be strongly endothermic, and thus cannot contribute much in splitting H2. The adsorption energy on the relatively unstable (101) surface was on the other hand approximately −0.6 eV, in the right range for surface H2 to be catalyzed beneficially. H adsorption on this surface was induced by surface states in the band gap of the clean surface. Since the unstable (101) surface is not abundant, the rate of dissociative adsorption of H2 on the LN surface can be anticipated to be very low. Application of the energies to simple adsorption isotherm calculations for typical proton conducting fuel cells (PCFCs) operating temperatures correspondingly showed very low H coverage, and it is not expected that LaNbO4 surfaces can contribute much to the H2 activation reaction of a PCFC anode.

• Hadidi, Kianoosh; Norby, Truls; Løvvik, Ole Martin & Gunnæs, Anette Eleonora (2012). Hydrogen energetics and charge transfer in the Ni/LaNbO4 interface from DFT calculations. International Journal of Hydrogen Energy. ISSN 0360-3199. 37(9), s. 8033–8042. doi: 10.1016/j.ijhydene.2011.11.032. Vis sammendrag

  Calculations based on density functional theory have been used to simulate interface structures between the tetragonal and monoclinic phases of LaNbO4 (LN) and Ni. Schottky barrier heights were calculated using the interface electronic structure; they were 3.0 and 1.8 eV for p- and n-type barriers. The hydrogen interstitials were found to be significantly higher stable in the LN part of the interface than in bulk LN. Also, the potential energy curve of hydrogen diffusion from Ni into LN exhibited a deep well of around 2 eV, located in the gap region between two components. The stability of H atom in the gap region and interfacial layers of LN is explained by metal-induced gap states and indicates that there will be an accumulation of hydrogen in this area. It was shown that hydrogen is ionized when enters from Ni to the LN interfacial layer, approaching to the O atoms and that the electron lost from hydrogen resides in the interface states, located in the band gap of LN.

• Kepaptsoglou, Despoina Maria; Hadidi, Kianoosh; Løvvik, Ole Martin; Magraso, Anna; Norby, Truls & Gunnæs, Anette Eleonora [Vis alle 8 forfattere av denne artikkelen] (2012). Interfacial Charge Transfer and Chemical Bonding in a Ni-LaNbO4 Cermet for Proton-Conducting Solid-Oxide Fuel Cell Anodes. Chemistry of Materials. ISSN 0897-4756. 24(21), s. 4152–4159. doi: 10.1021/cm302317f. Vis sammendrag

  In this work, we present an atomic scale study of the structural and chemical characteristics of interfaces between Ni and LaNbO4 grains in Ni–LaNbO4 cermets, a model composite material for anodes in proton-conducting solid-oxide fuel cells (SOFC). Electron energy loss spectroscopy (EELS) performed in an aberration-corrected scanning transmission electron microscope reveals the absence of reaction or interdiffusion layers at the interface. Changes in the valence state of Ni as well as in the electronic structure of La, reflected by changes in the EELS fine features at the interface, are shown to be related to charge transfer across the interface. The experimental results are in excellent agreement with ab initio calculations based on density functional theory, which predict that direct chemical bonds are formed between the metal and the ceramic at this abrupt interface, resulting in a redistribution of electronic charge across the interface.

• Sunding, Martin Fleissner; Hadidi, Kianoosh; Diplas, Spyridon; Løvvik, Ole Martin; Norby, Truls & Gunnæs, Anette Eleonora (2011). XPS characterisation of in situ treated lanthanum oxide and hydroxide using tailored charge referencing and peak fitting procedures. Journal of Electron Spectroscopy and Related Phenomena. ISSN 0368-2048. 184(7), s. 399–409. doi: 10.1016/j.elspec.2011.04.002.
• Magraso Sola, Anna; Frontera, Carlos; Gunnæs, Anette Eleonora; Tarancon, Albert; Marrero-López, David & Norby, Truls [Vis alle 7 forfattere av denne artikkelen] (2011). Structure, chemical stability and mixed proton-electron conductivity in BaZr0.9-xPrxGd0.1O3-delta. Journal of Power Sources. ISSN 0378-7753. 196(22), s. 9141–9147. doi: 10.1016/j.jpowsour.2011.06.076.
• Diplas, Spyridon; Løvvik, Ole Martin; Nordmark, Heidi; Kepaptsoglou, Despoina Maria; Graff, Joachim Seland & Ladam, Cecile [Vis alle 11 forfattere av denne artikkelen] (2010). Characterization of thin and ultrathin transparent conducting oxide (TCO) films and TCO-Si interfaces with XPS, TEM and ab initio modeling. Surface and Interface Analysis. ISSN 0142-2421. 42(6-7), s. 874–877. doi: 10.1002/sia.3355.
• Sunding, Martin Fleissner; Kepaptsoglou, Despoina Maria; Diplas, Spyridon; Norby, Truls & Gunnæs, Anette Eleonora (2010). XPS characterisation of the interface between anode and electrolyte in a proton conducting solid oxide fuel cell. Surface and Interface Analysis. ISSN 0142-2421. 42(6-7), s. 568–571. doi: 10.1002/sia.3383.
• Prytz, Øystein; Gunnæs, Anette Eleonora; Karlsen, Ole Bjørn; Breivik, Tallak Harald; Toberer, E. S. & Snyder, G. J. (2009). Nanoscale inclusions in the phonon glass thermoelectric material Zn4Sb3. Philosophical Magazine Letters. ISSN 0950-0839. 89(6), s. 362–369. doi: 10.1080/09500830902950464.

Se alle arbeider i Cristin

• Larsen, Aleksander; Poulia, Anthoula; S. Azar, Amin; Bazioti, Kalliopi; Almeida Carvalho, Patricia & Gunnæs, Anette Eleonora [Vis alle 9 forfattere av denne artikkelen] (2021). Identifying Magnetic Phases in Additively Manufactured High-Entropy Alloy FeCoNiAlxMnx.
• Bazioti, Kalliopi; Poulia, Anthoula; Løvvik, Ole Martin; S. Azar, Amin; Mikheenko, Pavlo & Diplas, Spyridon [Vis alle 7 forfattere av denne artikkelen] (2021). Advanced Scanning Transmission Electron Microscopy investigations of FeCoNi(AlMn)x high-entropy alloy: nanoscale structure and impact on magnetic properties.
• Bazioti, Kalliopi; Poulia, Anthoula; Løvvik, Ole Martin; S. Azar, Amin; Mikheenko, Pavlo & Diplas, Spyridon [Vis alle 7 forfattere av denne artikkelen] (2021). Structural evolution of FeCoNi(AlMn)x high-entropy alloy and impact on magnetic properties: nano-scale STEM-EELS investigations.
• Bazioti, Kalliopi; Poulia, Anthoula; Løvvik, Ole Martin; Almeida Carvalho, Patricia; S. Azar, Amin & Mikheenko, Pavlo [Vis alle 8 forfattere av denne artikkelen] (2021). STEM-EELS investigations and Lorentz microscopy unravelling the structural evolution of FeCoNi(AlMn)x high-entropy alloy and its impact on magnetic properties.
• Poulia, Anthoula; S. Azar, Amin; Gunnæs, Anette Eleonora; Bazioti, Kalliopi; Mikheenko, Pavlo & Diplas, Spyridon (2021). Tailoring mechanical and magnetic properties of the FeCoNi(AlMn)x high entropy alloys via compositional alterations.
• Poulia, Anthoula; S. Azar, Amin; Bazioti, Kalliopi; Gunnæs, Anette Eleonora; Mikheenko, Pavlo & Diplas, Spyridon (2021). Investigation of High Entropy Alloys via Magnetic Force Microscopy.
• Poulia, Anthoula; S. Azar, Amin; Bazioti, Kalliopi; Gunnæs, Anette Eleonora; Mikheenko, Pavlo & Diplas, Spyridon (2021). Additively manufactured FeCoNi(AlMn)x high entropy alloys: Mechanical and magnetic properties investigation.
• Almeida Carvalho, Patricia; Rahman, Jamil Ur; Soltani, Nayereh; Schrade, Matthias; Stange, Marit Synnøve Sæverud & Gunnæs, Anette Eleonora [Vis alle 8 forfattere av denne artikkelen] (2021). Functional high entropy antimonides and silicides.
• Almeida Carvalho, Patricia; Mayandi, Jeyanthinath; Rahman, Jamil Ur; Soltani, Nayereh; Schrade, Matthias & Gunnæs, Anette Eleonora [Vis alle 9 forfattere av denne artikkelen] (2021). Exploring the structure of high entropy oxides, silicides and antimonides for functional applications.
• Poulia, Anthoula; S. Azar, Amin; Svec, Peter; Bazioti, Kalliopi; Belle, Branson & Gunnæs, Anette Eleonora [Vis alle 8 forfattere av denne artikkelen] (2020). Nanoscale Magnetic Properties of Additively Manufactured FeCoNiAlxMnx High-Entropy Alloys.
• Kalyva, Maria Evangelou; Redekop, Evgeniy; Johansson, Niclas; Urpelainen, Samuli; Gunnæs, Anette Eleonora & Diplas, Spyridon [Vis alle 7 forfattere av denne artikkelen] (2019). AP-XPS study of bimetallic PtCu nanoparticles supported on SiO2 films.
• Sunding, Martin Fleissner; Løberg, Monika; S. Azar, Amin; Stange, Marit Synnøve Sæverud; Almeida Carvalho, Patricia & Karlsen, Ole Bjørn [Vis alle 10 forfattere av denne artikkelen] (2019). The Need for a Multi-Technique Approach in the Search for New Phase-Transforming Materials. Vis sammendrag

  Introduction/Purpose Reversible diffusionless first-order phase transformations are a fundamental part of phase change materials and shape memory alloys [1]. Some of these materials even possess useful physical characteristics that show abrupt changes e.g. in their electrical[2] and magnetic [3] polarizations. These phase transformations can be studied using multiple techniques, enabling access to different types of information including length scales and time periods, but how should this characterisation be approached? Methods TEM studies give highly relevant data in this field of research, from detailed crystallographic structures, to relative orientations between grains and phases and to the phase transformation temperature. However, TEM analyses are time consuming and requires small sample sizes and ad hoc preparation. High-throughput measurement techniques are thus required in the search for improved compositions and new materials in order to rapidly assess the properties of many samples or samples with graded composition [4]. Optical methods (for example unpolarised and polarised microscopy and thermal imaging) and electric conductivity measurements can for example be used to map phase transformation temperatures much faster and on much larger areas than traditional TEM techniques. XRD and SEM-EDS-EBSD can then be applied to obtain initial crystallographic and microstructure information on an intermediate size scale, before TEM is applied for the in-depth study of the most relevant compositions. Results We applied this multi-pronged approach in the search for Heusler and half-Heusler alloys with a low temperature martensitic phase transformation and with low thermal hysteresis, with potential applications in waste heat energy harvesting. Conclusions Drawing advantage of the strengths of multiple analysis techniques – with respect to the obtainable information, the sample size and/or the time frame of the analyses – renders the search for new phase change materials more effective. It enables faster identification of potential target compositions and of sample areas optimal for in depth studies. Selected references [1] David Dye, Nature Materials14 (8), 760 (2015). [2] M. M. Vopson, Critical Reviews in Solid State and Materials Sciences40 (4), 223 (2015). [3] L. Huang, D. Y. Cong, L. Ma, Z. H. Nie, Z. L. Wang, H. L. Suo, Y. Ren, and Y. D. Wang, Applied Physics Letters108 (3) (2016). [4] M. L. Green, C. L. Choi, J. R. Hattrick-Simpers, A. M. Joshi, I. Takeuchi, S. C. Barron, E. Campo, T. Chiang, S. Empedocles, J. M. Gregoire, A. G. Kusne, J. Martin, A. Mehta, K. Persson, Z. Trautt, J. Van Duren, and A. Zakutayev, Applied Physics Reviews 4 (1), 011105 (2017).

• Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Sørby, Magnus Helgerud; Wachowski, Sebastian Lech; Mielewczyk-Gryn, Aleksandra & Balaguer, Maria [Vis alle 9 forfattere av denne artikkelen] (2019). Hydration and hydrogenation of mixed conducting BaGd1‑xLaxCo2O6‑δ (BGLC).
• Løberg, Monika; Pike, Nicholas; Almeida Carvalho, Patricia; Karlsen, Ole Bjørn; Løvvik, Ole Martin & Gunnæs, Anette Eleonora (2019). Martensitic-like phase transformations within the Cu-Pd-Sn system .
• Løberg, Monika; Karlsen, Ole Bjørn; Løvvik, Ole Martin; Almeida Carvalho, Patricia & Gunnæs, Anette Eleonora (2019). Characterization of phase transformations within the Cu-Pd-Sn system - a possible shape memory alloy for energy conversion.
• Løberg, Monika; Pike, Nicholas; Karlsen, Ole Bjørn; Almeida Carvalho, Patricia; Løvvik, Ole Martin & Gunnæs, Anette Eleonora (2019). Characterization of phase transforming, Heusler based (Cu-Pd-Sn), alloys for energy harvesting. .
• Løberg, Monika; Løvvik, Ole Martin; Almeida Carvalho, Patricia; Karlsen, Ole Bjørn & Gunnæs, Anette Eleonora (2019). Phase Transformations within the Cu-Pd-Sn system.
• Strandbakke, Ragnar; Gunnæs, Anette Eleonora; Carvalho, Patricia A.; Mielewczyk-Gryn, Aleksandra; Wachowski, Sebastian & Balaguer, Maria [Vis alle 8 forfattere av denne artikkelen] (2018). Coupled hydration, cation reorganization and red-ox in MIEC perovskites .
• Løberg, Monika; Løvvik, Ole Martin & Gunnæs, Anette Eleonora (2018). Energy Conversion using Phase Transforming Materials - the Cu-Pd-Sn system.
• Løberg, Monika; Løvvik, Ole Martin & Gunnæs, Anette Eleonora (2018). Martensitic like phase transformations in the Cu-Pd-Sn system.
• de Ruiter, Lisa; Austrheim, Håkon Olaf; Gunnæs, Anette Eleonora & Dysthe, Dag Kristian (2018). Quartz dissolution and M-S-H cement precipitation in a high pH ultramafic system.
• de Ruiter, Lisa; Austrheim, Håkon Olaf; Dysthe, Dag Kristian & Gunnæs, Anette Eleonora (2018). Quartz weathering associated with magnesium silicate hydrate cement precipitation.
• Berland, Kristian; Eliassen, Simen Nut Hansen; Schrade, Matthias; Tofan, Raluca; Guzik, Matylda Natalia & Gunnæs, Anette Eleonora [Vis alle 11 forfattere av denne artikkelen] (2017). Using theory to understand thermoelectric materials.
• Guzik, Matylda N.; Schrade, Matthias; Tofan, Raluca; Berland, Kristian; Gunnæs, Anette Eleonora & Persson, Clas [Vis alle 8 forfattere av denne artikkelen] (2017). Structural Investigation of Ti1-xHfxNiySn Half-Heusler Compounds.
• Kepaptsoglou, Despoina Maria; Diplas, Spyridon; Gunnæs, Anette Eleonora & Ulyashin, Alexander (2017). On the evolution of properties of ITO layers deposited on crystalline and amorphous Si upon heat treatments.
• Gunnæs, Anette Eleonora; Diplas, Spyros & Ulyashin, Alexander G. (2017). A TEM and XPS study of epitaxially grown amorphous hydrogenated silicon in solar cell structures.
• Kepaptsoglou, Despoina Maria; Diplas, Spyridon; Ramasse, Quentin; Gunnæs, Anette Eleonora & Ulyashin, Alexander (2017). A high resolution electron microscopy and spectroscopy study of interfaces in Si-based solar cell heterojunctions.
• Gunnæs, Anette Eleonora (2017). Evaluation of a thermoelectric p-n junction at the macro and nano scale by X-ray and electron probe techniques.
• Lervik, Adrian; Bjørheim, Tor Svendsen; Nguyen, Phuong Dan; Diplas, Spyridon; Haugsrud, Reidar & Gunnæs, Anette Eleonora (2016). Chemical and Structural Investigations of Grain Boundaries in Y-Doped BaZrO3.
• Tofan, Raluca; Echevarria-Bonet, Cristina; Berland, Kristian; Schrade, Matthias; Sørby, Magnus Helgerud & Hauback, Bjørn Christian [Vis alle 10 forfattere av denne artikkelen] (2016). The effect of spark plasma sintering on structure and phase stability in half-Heusler thermoelectric alloys.
• Schrade, Matthias; Echevarria-Bonet, Cristina; Guzik, Matylda Natalia; Tofan, Raluca; Gunnæs, Anette Eleonora & Eliassen, Simen Nut Hansen [Vis alle 10 forfattere av denne artikkelen] (2016). Thermal properties of XNiSN (X = Ti, Zr, Hf) half Heusler alloys.
• Schrade, Matthias; Echevarria-Bonet, Cristina; Eliassen, Simen Nut Hansen; Berland, Kristian; Persson, Clas & Tofan, Raluca [Vis alle 9 forfattere av denne artikkelen] (2016). Thermal Properties of XNiSn(X = Hf, Zr, Ti) half Heusler Alloys.
• Tofan, Raluca; Echevarria-Bonet, Cristina; Berland, Kristian; Schrade, Matthias; Sørby, Magnus Helgerud & Hauback, Bjørn Christian [Vis alle 10 forfattere av denne artikkelen] (2016). Microstructural characterization of spark plasma sintered (X,X’)NiSn half‐Heusler alloys.
• Granerød, Cecilie Skjold; Nguyen, Phuong Dan; Gunnæs, Anette Eleonora & Prytz, Øystein (2016). The Structure Physics group.
• Gunnæs, Anette Eleonora (2016). Nanoscience with TEM at the Center for Material Science and Nanotechnology/NORTEM, Oslo, Norway.
• Song, Xin; Valset, Kjetil; Graff, Joachim Seland; Thøgersen, Annett; Gunnæs, Anette Eleonora & Carbalho, Partricia [Vis alle 9 forfattere av denne artikkelen] (2015). Nano Improves Thermoelectric Performance. Vis sammendrag

  The rule of thumb for improving the performance of thermoelectric materials is to reduce the thermal conduction, which attributes to electron transport and phonon transport. Phonons are characterized by different wavelength, Short wavelength phonons are scattered by impurity atoms in alloyed matels, Mid- and Long wavelength phonns are scattered by the iuinterfaces. Nanostructuring can engineer the phonon transport by introduce numerous grain boundaries, thus increasing phonon scattering, further improving thermal resistance. The aim of the present study is the nano-grains of the thermoelectric material ZnSb and the correlation with thermal transport measurements. We explored cryomilling (by ball-milling powders at Cryogenic temperature) as a technique to created nano—powders of ZnSb for pressing into pellets. The effect of cryomilling flowed by hot-pressing of undoped ZnSb was investigated.

• Echevarria-Bonet, Cristina; Tofan, Raluca; Schrade, Matthias; Gunnæs, Anette Eleonora; Persson, Clas & Sørby, Magnus Helgerud [Vis alle 7 forfattere av denne artikkelen] (2015). Enhancement of the thermoelectric properties in nanostructured half-Heusler alloys.
• Fjellvåg, Øystein Slagtern; Sjåstad, Anja Olafsen; Haugsrud, Reidar & Gunnæs, Anette Eleonora (2015). Investigation of Novel Hydride Oxides for Holistic Understanding of Functional Materials.
• Ulvestad, Asbjørn; Mæhlen, Jan Petter; Andersen, Hanne Flåten; Gunnæs, Anette Eleonora; Prytz, Øystein & Kirkengen, Martin (2015). Characterization of PECVD-Grown a-SiC:H for use as Coating for Silicon Thin Film Anodes in Li-Ion Batteries.
• Gunnæs, Anette Eleonora (2015). Atomkikking med Norges supermikroskop.
• Lervik, Adrian; Haugsrud, Reidar; Diplas, Spyridon & Gunnæs, Anette Eleonora (2015). A TEM approach to BZY.
• Løvvik, Ole Martin; Song, Xin; Valset, Kjetil; Flage-Larsen, Espen; Fjeld, Harald & Graff, Joachim Seland [Vis alle 14 forfattere av denne artikkelen] (2014). Thermoelectric materials from first principles to final applications: Basic and applied thermoelectrics in Oslo.
• Song, Xin; Valset, Kjetil; Graff, Joachim Seland; Thøgersen, Annett; Gunnæs, Anette Eleonora & Luxsacumar, Sivakanesar [Vis alle 7 forfattere av denne artikkelen] (2014). Nanostructuring by Cryomilling of Undoped ZnSb.
• Song, Xin; Persson, Clas; Norby, Truls; Flage-Larsen, Espen; Karlsen, Ole Bjørn & Hansen, Vidar [Vis alle 15 forfattere av denne artikkelen] (2014). Conversion of Heat and Energy: Thermoelectrics.
• Roaldset, Elen; Bering, Dag; Aerts, Maarten & Gunnæs, Anette E. (2013). Kaolinite Group minerals from weathered anorthosite, SW Norway. Berichte derDeutschen Ton- und Tonmineralgruppe e.V.. ISSN 1432-7007. 15, s. 27–27.
• Qureishy, Thomas; Hansen, Vidar; Karlsen, Ole Bjørn; Gunnæs, Anette Eleonora & Taftø, Johan (2012). Superstructures in Mg2Si1-xSnx.
• Holmestad, Randi; Walmsley, John Charles; Prytz, Øystein; Soleim, Bjørn Gunnar; Van Helvoort, Antonius & Olsen, Arne [Vis alle 18 forfattere av denne artikkelen] (2012). NORTEM – ambitions and plans.
• Norby, Truls; Fjeld, Harald; Gunnæs, Anette Eleonora; Hadidi, Kianoosh; Kepaptsoglou, Despoina Maria & Løvvik, Ole Martin [Vis alle 8 forfattere av denne artikkelen] (2010). Experimental and Computational Studies of Bulk and Interfaces of a Ceramic Proton Conductor at Atomic and Nano Scale.
• Hage, Fredrik Sydow; Helgesen, Geir; Gunnæs, Anette Eleonora & Prytz, Øystein (2010). Graphitization of carbon nanocones and nanodiscs.
• Hadidi, Kianoosh; Løvvik, Ole Martin; Norby, Truls & Gunnæs, Anette Eleonora (2010). Atomistic studies of LaNbO4 surfaces and Ni-LaNbO4 interface.
• stokkan, Therese S.; Gunnæs, Anette Eleonora; Kepaptsoglou, Despoina Maria & Magraso Sola, Anna (2010). Phase segregation in NiO/LaNbO4 composites.
• Sunding, Martin Fleissner; Kepaptsoglou, Despoina Maria; Diplas, Spyridon; Gunnæs, Anette Eleonora & Norby, Truls (2010). Metal-Oxide interfaces in proton conducting fuel cells studied by angle-resolved XPS.
• Prytz, Øystein; Gunnæs, Anette Eleonora; Breivik, Tallak Harald; Toberer, E. S.; Snyder, G. J. & Taftø, Johan (2009). Nanostructured thermoelectric materials, reduction of thermal conductivity in Zn4Sb3.
• Diplas, Spyridon; Løvvik, Ole Martin; Nordmark, Heidi; Kepaptsoglou, Despoina Maria; Graff, Joachim Moe & Gunnæs, Anette Eleonora (2009). Characterisation of transparent conducting oxide (TCO) films and TCO-Si interfaces with XPS, TEM and ab-initio modelling.
• Helgesen, Geir; Knudsen, K.D.; Skjeltorp, Arne Torbjørn; Knaapila, M.; Pinheiro, J.P. & Bourgeaux, M. [Vis alle 9 forfattere av denne artikkelen] (2009). The structure and properties of carbon cones.
• Fontaine, Marie-Laure; Larring, Yngve; Mei, Sen; Bredesen, Rune; Syvertsen, Guttorm E & Lein, H. L. [Vis alle 17 forfattere av denne artikkelen] (2009). Proton Conducting SOFCs – From Fundamental Understanding to Fuel Cell Stacks.
• Gunnæs, Anette Eleonora; Prytz, Øystein; Olsen, Arne; Helgesen, Geir & Knudsen, K. D. (2009). Structural study of C-cones and discs by use of analytical TEM.
• Hage, Frefrik Sydow; Gunnæs, Anette Eleonora; Olsen, Arne & Magraso Sola, Anna (2009). A structural study of lanthanum tungstate by CBED.
• Prytz, Øystein; Gunnæs, Anette Eleonora; Breivik, Tallak Harald; Toberer, Eric; Snyder, Jeff & Taftø, Johan (2008). Transmission Electron Microscopy Studies of Nanostructure in ß-Zn4Sb3.
• Prytz, Øystein; Gunnæs, Anette Eleonora; Toberer, Eric; Snyder, Jeff & Taftø, Johan (2008). Transmission electron microscopy search for defects and disorder causing the low thermal conductivity of Zn4Sb3.
• Gunnaes, Anette E.; Gunnæs, Anette Eleonora; Schrade, Matthias; Almeida Carvalho, Patricia & Røsvik, Mari Mathillas (2021). Structural Characterization of High Entropy Metal Silicide Alloys. An investigation of the Si:Cr:Fe:Co:Ni:Cu system. UiO.
• Solemsli, Bjørn Gading; Olsbye, Unni; Gunnæs, Anette Eleonora & Gutterød, Emil Sebastian (2020). A Study of Catalytic Pt Nanoparticles inside a Nano-porous Functionalized UiO MOF-matrix for CO2-Hydrogenation . Kjemisk Institutt, Universitetet i Oslo. Vis sammendrag

  Hydrogenation of carbon dioxide hasreceivedincreasingattentionin catalytic research the last decade as a sustainable alternativeforproducing high value chemicals thattodayare produced fromfossil fuels. The aim of this thesis has been two-fold: First, to study Pt nanoparticles formed in various UiO-66 and -67 metal-organic frameworks (MOFs) by Transmission Electron Microscopy (TEM), and second, to study the Pt-containing MOFs as catalysts for the CO2hydrogenation reaction.Three Zr-based UiO-66 MOF and nineUiO-67 MOF samples containing different amountsof functionalized linkers were impregnated withdifferent amounts ofK2PtCl4and reduced in H2at 350 ̊C for 4 hours to form Pt nanoparticles embedded in the MOF matrix.The samples were then testedin a H2/CO2feed at 8 bar and 170 ̊Cfor the hydrogenation reaction. After testing,TEMwas used to investigate the formation of Pt nanoparticles andtheir relationship with the surrounding MOF structure. The study revealed that, despite variable the linkers in the MOF,the conversion of CO2isdominated bythe reverse water-gas shift reaction,suggestingthat the linkers donot partakethe reactions mechanisms. Analysis usingTEMrevealedthat the Pt nanoparticles grow independently of its surroundings inside the MOFs with no observable growth relationshipwith the MOF. The nanoparticles are seen to grow into octahedral crystals that are larger than the pores in the framework. Samples with different amountsof missing linker type defects show that the presence of open Zr-node sitesenhances the selectivity towards methanol. A sample of Pt-functionalized UiO-67 with 10% [2,2’-bipyridine]5,5’-dicaboxylicacidlinker was oxidised toinduce missing linkerdefects post synthetically. After reduction in H2at 350 ̊C for 4 hours, the sample was oxidized in situin synthetic air for three different time spans. Careful analysis with N2-adsroption and TEM revealedthat the structure of the MOF deteriorates and loses accessible surface area with increasing timeon steam, while keeping the dispersion of the Pt nanoparticles. PXRD analysis revealedthe formation of tetragonal ZrO2. Extensive testsfrom 1-30 bar and 170-375 ̊C reveal a lower conversion and higher selectivity towards methanol for a fully calcined sample, indicating that the Zr-nodes behave similarlyto non-MOF ZrO2supports. Transient kinetic studies of the parent UiO-67 sample revealedthat the sample behaves similarlytopreviously studied systemsby Gutterød et al., and showed the presence of an inverse kinetic isotope effect for methane and methanolformation upon H2/D2exchange.

• Fjellvåg, Øystein; Sjåstad, Anja Olafsen & Gunnæs, Anette Eleonora (2019). Oxyhydrides - Synthesis, Crystal Structure and Properties. Universitetet i Oslo. ISSN 1501-7710. 2019(2153).
• Løberg, Monika & Gunnæs, Anette Eleonora (2017). Influence of Mn Stoichiometry on the Structure and Thermoelectric Properties of CaMn(1+y)O(3-d). University of Oslo (UiO). Vis sammendrag

  The energy consumption of present day society is ever increasing and the sources for more and cleaner energy is sought for. A possible contributor are thermoelectric generators, which convert parts of a heat flux directly into electrical energy. Unfortunately, the efficiency of current generators is too low for large scale commercialization, and new and better materials must be designed. In the present master project, the performance of n-type thermoelectric oxide CaMn(1+y)O(3-d) is attempted improved by creating precipitates within the nano-range. The precipitates could be anticipated to enhance phonon scattering, thereby lowering thermal conductivity and enhance the overall thermoelectric properties of the material. A sample series of CaMn(1+y)O(3-d), with composition y = 0, 0.020 , 0.036, 0.074 and 0.10, has been synthesized by solid state reaction and the microstructure and thermoelectric properties were characterized. Secondary phase, CaMn2O4, precipitates were found from X-ray diffraction and Scanning Electron Microscopy in the size range 5-10 um. Further investigations into the presence of nanoprecipitates were performed by Transmission Electron Microscopy finding no areas enriched in manganese within the CaMnO3 matrix. Electrical resistivity and Seebeck coefficient were measured from room temperature up to 600C finding a resistivity ranging from 20 - 100 mOhm cm and Seebeck coefficient from -300 to -200 uVK-1, showing no trend with manganese content. Thermal conductivity measurements were performed, showing a thermal conductivity between 2.3 - 3.6 Wm-1K-1, however no trend with varying manganese content was observed. Further, the obtained thermoelectric data was compared with samples fabricated using a different synthesis method, yielding similar results and no significant variations was observed. The absence of a Mn-dependency in all transport parameters was carefully confirmed by a thorough investigation of potential experimental influences, like sample porosity, impurity level and measurement uncertainty. Finally, the results are qualitatively rationalized using a simple Callaway model for the thermal conductivity. The concluding remarks are that all manganese excess will manifest as secondary phase CaMn2O4 and no manganese rich precipitates will exist within the CaMnO3 matrix. The variation in manganese content does not influence the thermoelectric properties of CaMn(1+y)O(3-d).

• Lervik, Adrian; Haugsrud, Reidar; Diplas, Spyridon & Gunnæs, Anette Eleonora (2016). Structural- and Compositional Investigations of Grain Boundaries in Y-Doped BaZrO3. Universitetet i Oslo.
• Povia, Mauro; Sartori, Sabrina & Gunnæs, Anette Eleonora (2015). In Situ Operando SAXS and WAXS Characterization of the Anode Materials (a-P/C and FeSb2) for Rechargeable Sodium Ion Batteries. Department of Physics, UiO.
• Hadidi, Kianoosh; Løvvik, Ole Martin; Norby, Truls Eivind & Gunnæs, Anette Eleonora (2012). Atomistic study of interfaces in the anode electrode of proton conducting fuel cells. Universitetet i Oslo.

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