ragnarst

• Miruszewski, Tadeusz; Strandbakke, Ragnar; Dzierzgowski, Kacper; Szpunar, Iga; Mielewczyk-Gryń, Aleksandra & Wachowski, Sebastian [Vis alle 7 forfattere av denne artikkelen] (2024). A modified DC Hebb-Wagner polarization method for determining the partial protonic electrical conductivity in mixed-conducting BaGd<inf>0.3</inf>La<inf>0.7</inf>Co<inf>2</inf>O<inf>6−δ</inf>. Journal of Materials Chemistry A. ISSN 2050-7488. doi: 10.1039/d4ta00100a.
• Dayaghi, Amir Masoud; Polfus, Jonathan M.; Strandbakke, Ragnar; Pokle, Anuj; Almar, Laura & Escolastico, Sonia [Vis alle 10 forfattere av denne artikkelen] (2023). Effects of sintering additives on defect chemistry and hydration of BaZr0.4Ce0.4(Y,Yb)0.2O3−δ proton conducting electrolytes. Solid State Ionics. ISSN 0167-2738. 401. doi: 10.1016/j.ssi.2023.116355.
• Balcerzak, Daria; Szpunar, Iga; Strandbakke, Ragnar; Saeed, Sarmad Waheed; Bazioti, Kalliopi & Mielewczyk-Gryń, Aleksandra [Vis alle 12 forfattere av denne artikkelen] (2023). Oxide nanoparticle exsolution in Lu-doped (Ba,La)CoO3. CrysteEngComm. ISSN 1466-8033. 25(30), s. 4306–4316. doi: 10.1039/d3ce00422h.
• Mielewczyk-Gryń, Aleksandra; Yang, Shuhao; Balaguer, Maria; Strandbakke, Ragnar; Sørby, Magnus Helgerud & Szpunar, Iga [Vis alle 11 forfattere av denne artikkelen] (2023). Energetics of formation and stability in high pressure steam of barium lanthanide cobaltite double perovskites. Dalton Transactions. ISSN 1477-9226. 52(17), s. 5771–5779. doi: 10.1039/d2dt03989c.
• Strandbakke, Ragnar; Wragg, David Stephen; Sørby, Magnus Helgerud; Guzik, Matylda; Gunnæs, Anette Eleonora & Szpunar, Iga [Vis alle 12 forfattere av denne artikkelen] (2022). Structural properties of mixed conductor Ba1−xGd1−yLax+yCo2O6−δ. Dalton Transactions. ISSN 1477-9226. 51(48), s. 18667–18677. doi: 10.1039/d2dt02277j. Fulltekst i vitenarkiv Vis sammendrag

  Ba1−xGd1−yLax+yCo2O6−δ (BGLC) compositions with large compositional ranges of Ba, Gd, and La have been characterised with respect to phase compositions, structure, and thermal and chemical expansion. The results show a system with large compositional flexibility, enabling tuning of functional properties and thermal and chemical expansion. We show anisotropic chemical expansion and detailed refinements of emerging phases as La is substituted for Ba and Gd. The dominating phase is the double perovskite structure Pmmm, which is A-site ordered along the c-axes and with O vacancy ordering along the b-axis in the Ln-layer. Phases emerging when substituting La for Ba are orthorhombic Ba-deficient Pbnm and cubic LaCoO3-based R[3 with combining macron]c. When La is almost completely substituted for Gd, the material can be stabilised in Pmmm, or cubic Pm[3 with combining macron]m, depending on thermal and atmospheric history. We list thermal expansion coefficients for x = 0–0.3, y = 0.2.

• Vijayan Sobhana, Dilimon; Strandbakke, Ragnar & Norby, Truls (2022). Impedance spectroscopy study of Au electrodes on Gd-doped CeO<inf>2</inf> (GDC) – Molten Li<inf>2</inf>CO<inf>3</inf>+Na<inf>2</inf>CO<inf>3</inf> (LNC) composite electrolytes. Journal of Power Sources. ISSN 0378-7753. 522. doi: 10.1016/j.jpowsour.2022.230986. Fulltekst i vitenarkiv
• Emhjellen, Linn Katinka Susanne Shi; Strandbakke, Ragnar & Haugsrud, Reidar (2021). Electrical transport in a molten-solid V2O5–ZrV2O7 composite. Journal of Materials Chemistry A. ISSN 2050-7488. 9(34), s. 18537–18545. doi: 10.1039/D1TA03750A. Fulltekst i vitenarkiv
• Zhu, Junjie; Gudmundsdottir, Jonina Björg; Strandbakke, Ragnar; Both, Kevin Gregor; Aarholt, Thomas & Almeida Carvalho, Patricia [Vis alle 12 forfattere av denne artikkelen] (2021). Double Perovskite Cobaltites Integrated in a Monolithic and Noble Metal-Free Photoelectrochemical Device for Efficient Water Splitting. ACS Applied Materials & Interfaces. ISSN 1944-8244. 13(17), s. 20313–20325. doi: 10.1021/acsami.1c01900. Fulltekst i vitenarkiv Vis sammendrag

  Water photoelectrolysis has the potential to produce renewable hydrogen fuel, therefore addressing the intermittent nature of sunlight. Herein, a monolithic, photovoltaic (PV)-assisted water electrolysis device of minimal engineering and of low (in the μg range) noble-metal-free catalysts loading is presented for unassisted water splitting in alkaline media. An efficient double perovskite cobaltite catalyst, originally developed for high-temperature proton-conducting ceramic electrolyzers, possesses high activity for the oxygen evolution reaction in alkaline media at room temperatures too. Ba1–xGd1–yLax+yCo2O6−δ (BGLC) is combined with a NiMo cathode, and a solar-to-hydrogen efficiency of 6.6% in 1.0 M NaOH, under 1 sun simulated illumination for 71 h, is demonstrated. This work highlights how readily available earth-abundant materials and established PV methods can achieve high performance and stable and monolithic photoelectrolysis devices with potential for full-scale applications.

• Dayaghi, Amir Masoud; Haugsrud, Reidar; Stange, Marit Synnøve Sæverud; Larring, Yngve; Strandbakke, Ragnar & Norby, Truls Eivind (2021). Increasing the thermal expansion of proton conducting Y-doped BaZrO3 by Sr and Ce substitution. Solid State Ionics. ISSN 0167-2738. 359. doi: 10.1016/j.ssi.2020.115534. Fulltekst i vitenarkiv Vis sammendrag

  Proton conducting oxide electrolytes find potential application in proton ceramic fuel cells and electrolyzers operating at intermediate temperatures, e.g. 400–600 °C. However, state-of-the-art proton conducting ceramics based on Y-doped BaZrO3 (BZY) have lower thermal expansion coefficient (TEC) than most commonly applied or conceived supporting electrode structures, making the assembly vulnerable to degradation due to cracks or spallation. We have increased the TEC of 20 mol% Y-doped BZY (BZY20) by partially substituting Ba and Zr with Sr and Ce, respectively, to levels which still maintain the cubic structure and sufficiently minor n-type conduction; (Ba0.85Sr0.15)(Zr0.7Ce0.1Y0.2)O2.9 (BSZCY151020). High temperature XRD shows that this material has a cubic structure (space group ) in the temperature range of 25–1150 °C and a linear TEC of ~10 × 10−6 K−1, as compared to the ~8 × 10−6 K−1 for BZY. It exhibited a DC conductivity of ~5 mS cm−1 at 600 °C in wet H2. This electrolyte with increased TEC may find application in proton ceramic electrochemical cells in general and metal supported ones in particular.

• Szpunar, Iga; Strandbakke, Ragnar; Sørby, Magnus Helgerud; Wachowski, Sebastian Lech; Balaguer, Maria & Tarach, Mateusz [Vis alle 12 forfattere av denne artikkelen] (2020). High-temperature structural and electrical properties of BaLnCo2O6 positrodes. Materials. ISSN 1996-1944. 13(18), s. 1–18. doi: 10.3390/ma13184044. 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
• Andersen, Håkon; Xu, Kaiqi; Malyshkin, Dmitry; Strandbakke, Ragnar & Chatzitakis, Athanasios Eleftherios (2020). A highly efficient electrocatalyst based on double perovskite cobaltites with immense intrinsic catalytic activity for water oxidation. Chemical Communications. ISSN 1359-7345. 56(7), s. 1030–1033. doi: 10.1039/c9cc08765f.
• Szpunar, Iga; Wachowski, Sebastian; Miruszewski, Tadeusz; Dzierzgowski, Kacper; Górnicka, Karolina & Klimczuk, Tomasz [Vis alle 12 forfattere av denne artikkelen] (2019). Electric and magnetic properties of Lanthanum Barium Cobaltite. Journal of The American Ceramic Society. ISSN 0002-7820. 103(3), s. 1809–1818. doi: 10.1111/jace.16865. Fulltekst i vitenarkiv
• Vøllestad, Einar; Strandbakke, Ragnar; Tarach, Mateusz; Catalán-Martinez, David; Fontaine, Marie-Laure & Beeaff, Dustin [Vis alle 9 forfattere av denne artikkelen] (2019). Mixed proton and electron conducting double perovskite anodes for stable and efficient tubular proton ceramic electrolysers. Nature Materials. ISSN 1476-1122. 18(7), s. 752–759. doi: 10.1038/s41563-019-0388-2. Fulltekst i vitenarkiv Vis sammendrag

  Hydrogen production from water electrolysis is a key enabling energy storage technology for the large-scale deployment of intermittent renewable energy sources. Proton ceramic electrolysers (PCEs) can produce dry pressurized hydrogen directly from steam, avoiding major parts of cost-driving downstream separation and compression. However, the development of PCEs has suffered from limited electrical efficiency due to electronic leakage and poor electrode kinetics. Here, we present the first fully operational BaZrO3-based tubular PCE, with 10 cm2 active area and a hydrogen production rate above 15 Nml min−1. The novel steam anode Ba1−xGd0.8La0.2+xCo2O6−δ exhibits mixed p-type electronic and protonic conduction and low activation energy for water splitting, enabling total polarization resistances below 1 Ω cm2 at 600 °C and Faradaic efficiencies close to 100% at high steam pressures. These tubular PCEs are mechanically robust, tolerate high pressures, allow improved process integration and offer scale-up modularity.

• Kaklidis, N.; Strandbakke, Ragnar; Arenillas, A.; Menendez, Javier A; Konsolakis, M. & Marnellos, G.E. (2019). The synergistic catalyst-carbonates effect on the direct bituminous coal fuel cell performance. International Journal of Hydrogen Energy. ISSN 0360-3199. 44(20), s. 10033–10042. doi: 10.1016/j.ijhydene.2019.02.038. Fulltekst i vitenarkiv
• Sun, Xinwei; Xu, Kaiqi; Fleischer, Christian; Liu, Xin; Grandcolas, Mathieu & Strandbakke, Ragnar [Vis alle 9 forfattere av denne artikkelen] (2018). Earth-abundant electrocatalysts in proton exchange membrane electrolyzers. Catalysts. ISSN 2073-4344. 8:657(12), s. 1–41. doi: 10.3390/catal8120657. Fulltekst i vitenarkiv Vis sammendrag

  In order to adopt water electrolyzers as a main hydrogen production system, it is critical to develop inexpensive and earth-abundant catalysts. Currently, both half-reactions in water splitting depend heavily on noble metal catalysts. This review discusses the proton exchange membrane (PEM) water electrolysis (WE) and the progress in replacing the noble-metal catalysts with earth-abundant ones. The efforts within this field for the discovery of efficient and stable earth-abundant catalysts (EACs) have increased exponentially the last few years. The development of EACs for the oxygen evolution reaction (OER) in acidic media is particularly important, as the only stable and efficient catalysts until now are noble-metal oxides, such as IrOx and RuOx. On the hydrogen evolution reaction (HER) side, there is significant progress on EACs under acidic conditions, but there are very few reports of these EACs employed in full PEM WE cells. These two main issues are reviewed, and we conclude with prospects for innovation in EACs for the OER in acidic environments, as well as with a critical assessment of the few full PEM WE cells assembled with EACs.

• Konsolakis, M.; Kaklidis, N.; Kyriakou, V.; Garagounis, I.; Kraia, Tzouliana & Arenillas, A. [Vis alle 9 forfattere av denne artikkelen] (2018). The combined impact of carbon type and catalyst-aided gasification process on the performance of a Direct Carbon Solid Oxide Fuel Cell. Solid State Ionics. ISSN 0167-2738. 317, s. 268–275. doi: 10.1016/j.ssi.2018.01.026.
• Kraia, Tzouliana; Wachowski, Sebastian Lech; Vøllestad, Einar; Strandbakke, Ragnar; Konsolakis, M. & Norby, Truls Eivind [Vis alle 7 forfattere av denne artikkelen] (2017). Electrochemical performance of Co3O4/CeO2 electrodes in H2S/H2O atmospheres in a proton-conducting ceramic symmetrical cell with BaZr0.7Ce0.2Y0.1O3 solid electrolyte. Solid State Ionics. ISSN 0167-2738. 306, s. 31–37. doi: 10.1016/j.ssi.2017.04.010. Fulltekst i vitenarkiv
• Bausa, Nuria; Solis, Cecilia; Strandbakke, Ragnar & Serra, José Manuel (2017). Development of composite steam electrodes for electrolyzers based on barium zirconate. Solid State Ionics. ISSN 0167-2738. 306, s. 62–68. doi: 10.1016/j.ssi.2017.03.020. Fulltekst i vitenarkiv
• Strandbakke, Ragnar; Vøllestad, Einar; Robinson, Shay Alexander; Fontaine, Marie-Laure & Norby, Truls Eivind (2017). Ba0.5Gd0.8La0.7Co2O6-δ infiltrated in porous BaZr0.7Ce0.2Y0.1O3 backbones as electrode material for proton ceramic electrolytes. Journal of the Electrochemical Society. ISSN 0013-4651. 164(4), s. F196–F202. doi: 10.1149/2.0141704jes.
• Vøllestad, Einar; Schrade, Matthias; Segalini, Julie; Strandbakke, Ragnar & Norby, Truls Eivind (2017). Relating defect chemistry and electronic transport in the double perovskite Ba1-xGd0.8La0.2+xCo2O6-d (BGLC). Journal of Materials Chemistry A. ISSN 2050-7488. 5(30), s. 15743–15751. doi: 10.1039/c7ta02659e. Fulltekst i vitenarkiv
• Kaklidis, N.; Kyriakou, V.; Marnellos, G.E.; Strandbakke, Ragnar; Arenillas, A. & Menendez, JA [Vis alle 7 forfattere av denne artikkelen] (2016). Effect of fuel thermal pretreament on the electrochemical performance of a direct lignite coal fuel cell. Solid State Ionics. ISSN 0167-2738. 288, s. 140–146. doi: 10.1016/j.ssi.2015.12.003.
• Strandbakke, Ragnar; Dyrlie, Oddvar; Hage, Fredrik Sydow & Norby, Truls (2016). Reaction kinetics of protons and oxide ions in LSM/lanthanum tungstate cathodes with Pt nanoparticle activation. Journal of the Electrochemical Society. ISSN 0013-4651. 163(6), s. F507–F515. doi: 10.1149/2.0881606jes.
• Strandbakke, Ragnar; Cherepanov, Vladimir A.; Zuev, Andrey Yu.; Tsvetkov, Dmitry S.; Argirusis, Christos & Sourkouni, Georgia [Vis alle 8 forfattere av denne artikkelen] (2015). Gd- and Pr-based double perovskite cobaltites as oxygen electrodes for proton ceramic fuel cells and electrolyser cells. Solid State Ionics. ISSN 0167-2738. 278, s. 120–132. doi: 10.1016/j.ssi.2015.05.014.
• Magraso Sola, Anna; Fontaine, Marie-Laure; Larring, Yngve; Bredesen, Rune; Syvertsen, Guttorm Ernst & Lein, Hilde Lea [Vis alle 11 forfattere av denne artikkelen] (2011). Development of Proton Conducting SOFCs Based on LaNbO4 Electrolyte - Status in Norway. Fuel Cells. ISSN 1615-6846. 11(1), s. 17–25. doi: 10.1002/fuce.201000052.
• Magraso Sola, Anna; Xuriguera, Helena; Varela, Manuel; Sunding, Martin Fleissner; Strandbakke, Ragnar & Haugsrud, Reidar [Vis alle 7 forfattere av denne artikkelen] (2010). Novel Fabrication of Ca-Doped LaNbO4 Thin-Film Proton-Conducting Fuel Cells by Pulsed Laser Deposition. Journal of The American Ceramic Society. ISSN 0002-7820. 93(7), s. 1874–1878. doi: 10.1111/j.1551-2916.2010.03650.x.
• Strandbakke, Ragnar; Kongshaug, Camilla; Haugsrud, Reidar & Norby, Truls (2009). High-Temperature Hydration and Conductivity of Mayenite, Ca12Al14O33. Journal of Physical Chemistry C. ISSN 1932-7447. 113(20), s. 8938–8944. doi: 10.1021/jp9009299.

Se alle arbeider i Cristin

• Roen, Stine; Norby, Truls; Strandbakke, Ragnar & Polfus, Jonathan M. (2023). Electrochemical characterization of Ba0.95La0.05(Fe0.7Ni0.2Zn0.1)O3-δ for proton ceramic electrochemical cells.
• Strandbakke, Ragnar (2023). Hydration, stability and electrochemistry of electrode materials for proton ceramic electrochemical cells.
• Småbråten, Didrik Rene; Polfus, Jonathan; Strandbakke, Ragnar; Singh, Kalpana; Veenstra, Peter & Fontaine, Marie-Laure (2023). DFT modelling of thermodynamic and kinetic parameters in electrochemical proton ceramic conducting cells.
• Strandbakke, Ragnar; Singh, Kalpana & Norby, Truls (2022). Effect of partial conductivities on the polarisation resistance of positrodes for proton ceramic fuel cells and electrolysers.
• Singh, Kalpana; Norby, Truls & Strandbakke, Ragnar (2022). Effect of partial conductivities on the polarisation resistance of positrodes for proton ceramic fuel cells and electrolysers.
• Chatzitakis, Athanasios; Zhu, Junjie; Gudmundsdottir, Jonina Björg; Strandbakke, Ragnar; Both, Kevin Gregor & Aarholt, Thomas [Vis alle 12 forfattere av denne artikkelen] (2022). A monolithic and noble metal-free photoelectrochemical device of minimal engineering for efficient, unassisted water splitting.
• Dayaghi, Amir Masoud; Polfus, Jonathan; Strandbakke, Ragnar; Vøllestad, Einar; Haugsrud, Reidar & Norby, Truls (2022). Effects of NiO, ZnO and CuO sintering additives on the hydration of BaZr0.4Ce0.4(Y,Yb)0.2O3-δ proton conducting electrolytes.
• Strandbakke, Ragnar; Balaguer, María; Carrillo, Alfonso; Wachowski, Sebastian Lech; Mielewczyk-Gryń, Aleksandra & Szpunar, Iga [Vis alle 13 forfattere av denne artikkelen] (2021). Hydration and electrochemistry of mixed conducting cobaltites.
• Strandbakke, Ragnar; Balaguer, María; Carrillo, Alfonso; Wachowski, Sebastian Lech; Mielewczyk-Gryń, Aleksandra & Szpunar, Iga [Vis alle 14 forfattere av denne artikkelen] (2021). Hydration and electrochemistry of mixed conducting cobaltites.
• Saeed, Sarmad Waheed & Strandbakke, Ragnar (2020). Resent Activities in FunKeyCat.
• Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Sørby, Magnus Helgerud; Szpunar, Iga; Wachowski, Sebastian Lech & Mielewczyk-Gryń, Aleksandra [Vis alle 10 forfattere av denne artikkelen] (2020). Governing principles of hydration in mixed conducting oxides.
• Saeed, Sarmad Waheed & Strandbakke, Ragnar (2019). FunKeyCat - An Overview.
• Strandbakke, Ragnar; Saeed, Sarmad Waheed & Carrillo, Alfonso (2019). Exsolution activities in the FunKeyCat project: Exsolving oxide nano-catalysts from cathode materials.
• Strandbakke, Ragnar; Vøllestad, Einar; Sørby, Magnus Helgerud & Norby, Truls Eivind (2019). Defect chemistry of mixed conducting double perovskites .
• Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Sørby, Magnus Helgerud; Szpunar, Iga; Wachowski, Sebastian Lech & Mielewczyk-Gryn, Aleksandra [Vis alle 9 forfattere av denne artikkelen] (2019). Protons in mixed conducting Ba1‑xGd1‑yLax+yCo2O6‑δ (BGLC).
• 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).
• Strandbakke, Ragnar; Balaguer, Maria; Wachowski, Sebastian Lech; Mielewczyk-Gryn, Aleksandra; Almeida Carvalho, Patricia & Sørby, Magnus Helgerud [Vis alle 7 forfattere av denne artikkelen] (2019). Protonics, stability and electrochemistry of Ba1‑xGd1-yLax+yCo2O6-δ (BGLC).
• Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Vøllestad, Einar; Mielewczyk-Gryn, Aleksandra; Wachowski, Sebastian Lech & Lewandowska, Iga [Vis alle 9 forfattere av denne artikkelen] (2019). Defect chemistry of mixed conducting double perovskites .
• Strandbakke, Ragnar; Wragg, David; Carvalho, Patricia; Mielewczyk-Gryn, Aleksandra; Wachowski, Sebastian & Balaguer, Maria [Vis alle 8 forfattere av denne artikkelen] (2018). Coupled hydration and red-ox in MIEC BGLC perovskites .
• Balaguer, Maria; Tarach, Mateusz; Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Mielewczyk-Gryn, Aleksandra & Wachowski, Sebastian [Vis alle 11 forfattere av denne artikkelen] (2018). Hydration Stability of Mixed Conducting Layered Oxides .
• Wachowski, Sebastian; Levandowska, Iga; Sørby, Magnus Helgerud; Balaguer, Maria; Bjørheim, Tor Svendsen & Gazda, Maria [Vis alle 10 forfattere av denne artikkelen] (2018). Governing Principles in Hydration of Mixed Conducting Oxides: Structure and Hydration of BaLnCo2O6-d.
• Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Mielewczyk-Gryn, Aleksandra; Wachowski, Sebastian; Lewandowska, Iga & Balaguer, Maria [Vis alle 10 forfattere av denne artikkelen] (2018). Governing Principles in Hydration of Mixed Conducting Oxides.
• 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 .
• Strandbakke, Ragnar; Vøllestad, Einar; Norby, Truls Eivind; Sartori, Sabrina; Guzik, Matylda Natalia & Lang, Julien (2017). Hydration and structural properties of mixed conductor Ba1‑xGd0.8La0.2+xCo2O6-δ (BGLC).
• Strandbakke, Ragnar; Vøllestad, Einar & Norby, Truls Eivind (2017). Development of oxygen-side electrodes for proton conducting fuel cells and electrolysers.
• Strandbakke, Ragnar; Vøllestad, Einar; Norby, Truls Eivind; Sartori, Sabrina; Guzik, Matylda Natalia & Lang, Julien (2017). Hydration and structural properties of mixed conductor Ba1‑xGd0.8La0.2+xCo2O6-δ (BGLC).
• Norby, Truls; Strandbakke, Ragnar; Chen, Min; Robinson, Shay Alexander & Kjølseth, Christian (2016). Fundamentals of electrodes for ceramic proton conducting electrolytes.
• Fontaine, Marie-Laure; Xing, Wen; Bredesen, Rune; Denonville, Christelle; Polfus, Jonathan M. & Strandbakke, Ragnar [Vis alle 10 forfattere av denne artikkelen] (2016). Proton conducting electrolysers with tubular segmented-in-series cells for hydrogen production.
• Vøllestad, Einar; Strandbakke, Ragnar; Beeaff, Dustin & Norby, Truls (2016). Proton Ceramic Steam Electrolysers.
• Norby, Truls; Strandbakke, Ragnar; Vøllestad, Einar; Chen, Min; Robinson, Shay Alexander & Kjølseth, Christian (2016). Proton ceramic electrodics.
• Vøllestad, Einar; Strandbakke, Ragnar & Norby, Truls (2016). Tailoring the properties of BGLC double perovskites.
• Vøllestad, Einar; Strandbakke, Ragnar; Beaff, Dustin & Norby, Truls (2016). Proton Ceramic Steam Electrolysers.
• Strandbakke, Ragnar; Vøllestad, Einar; Prato, Rafael Alberto; Wragg, David; Sartori, Sabrina & Norby, Truls (2016). Structural and electrochemical properties of hydrated mixed conductor Ba1-xGd0.8La0.2+xCo2O6-d.
• Strandbakke, Ragnar; Vøllestad, Einar; Prato, Rafael Alberto; Wragg, David & Norby, Truls (2016). Structural and electrochemical properties of hydrated mixed conductor Ba1-xGd0.8La0.2+xCo2O6-d.
• Norby, Truls; Fontaine, Marie-Laure; Strandbakke, Ragnar; Denonville, Christelle; Vøllestad, Einar & Vigen, Camilla Kaori [Vis alle 8 forfattere av denne artikkelen] (2016). Development of tubular proton conducting electrolysers.
• Fontaine, Marie-Laure; Denonville, Christelle; Strandbakke, Ragnar; Vøllestad, Einar; Norby, Truls & Bredesen, Rune [Vis alle 8 forfattere av denne artikkelen] (2016). Proton conducting electrolytes integrated in tubular segmented-in-series cells for pressurized hydrogen production.
• Vøllestad, Einar; Fontaine, Marie-Laure; Denonville, Christelle; Strandbakke, Ragnar; Norby, Truls & Vigen, Camilla Kaori [Vis alle 7 forfattere av denne artikkelen] (2016). Development of tubular proton conducting electrolysers.
• Fontaine, Marie-Laure; Denonville, Christelle; Strandbakke, Ragnar; Serra, José Manuel; Beeaff, Dustin R. & Vigen, Camilla Kaori [Vis alle 8 forfattere av denne artikkelen] (2016). Development of Tubular Proton Ceramic Electrolysers (PCEs).
• Vøllestad, Einar & Strandbakke, Ragnar (2015). Den nye vannkraften. Aftenposten Viten. ISSN 2464-3033.
• Strandbakke, Ragnar; Vøllestad, Einar & Norby, Truls (2015). Characterization of ionic transport and electrode kinetics in systems with multiple charge carriers .
• Strandbakke, Ragnar; Vøllestad, Einar & Norby, Truls (2015). Characterization of electrodes on ionic conductors with transport of more than one type of charge carriers.
• Strandbakke, Ragnar; Vøllestad, Einar & Norby, Truls (2015). Characterization of double perovskite electrodes on ionic conductors with transport of more than one type of charge carriers .
• Strandbakke, Ragnar; Vøllestad, Einar & Norby, Truls (2015). Investigation of Ba1-xGd0.8La0.2+xCo2O6-δ as Oxygen Electrode Material for Proton Conducting Fuel Cells and Electrolyzer Cells.
• Strandbakke, Ragnar; Vøllestad, Einar & Norby, Truls (2015). Investigation of BaGd0.8La0.2Co2O6-δ as Oxygen Electrode Material for Proton Conducting Fuel Cells and Electrolyzer Cells .
• Vøllestad, Einar; Strandbakke, Ragnar; Fontaine, Marie-Laure & Norby, Truls (2015). Infiltrated Double Perovskite Electrodes for Proton Conducting Steam Electrolysers.
• Vøllestad, Einar; Strandbakke, Ragnar & Norby, Truls (2015). Infiltrated Double Perovskite Electrodes for Proton Conducting Steam Electrolysers.
• Evans, Anna; Strandbakke, Ragnar; Patricio, Sonia; Marques, Fernando & Norby, Truls (2015). Ionic transport in ceramic-carbonate composites.
• Evans, Anna; Xing, Wen; Strandbakke, Ragnar & Norby, Truls (2015). Transport properties of molten carbonates and ceria-carbonate composites.
• Strandbakke, Ragnar; Norby, Truls; Zuev, Andrey; Cherepanov, Vladimir & Argirusis, Christos (2014). Model and methodology for investigation of oxygen electrodes on BZCY* electrolytes.
• Strandbakke, Ragnar; Evans, Anna & Norby, Truls (2014). Investigation of the ionic transport in ceramic-carbonate composites.
• Norby, Truls; Strandbakke, Ragnar; Cherepanov, Vladimir; Zuev, Andrey & Argirusis, Christos (2014). Model and methodology for investigation of oxygen electrodes on BZCY electrolytes.
• Norby, Truls; Strandbakke, Ragnar; Evans, Anna & Xing, Wen (2014). Characterisation of transport in oxides with more than one ionic charge carrier.
• Strandbakke, Ragnar (2013). Gd and Pr-based double perovskite cobaltites as air side electrodes for Proton Conducting Solid Oxide Fuel Cells / Electrolyzer Cells.
• Strandbakke, Ragnar (2013). Recent developments in air side electrodes for PC-SOFC / PC-SOEC.
• Strandbakke, Ragnar; Norby, Truls & Haugsrud, Reidar (2010). A study of Pt electrodes on proton conducting Ca-doped LaNbO4.
• Norby, Truls; Kjølseth, Christian; Strandbakke, Ragnar; Magraso Sola, Anna & Fontaine, Marie-Laure (2009). Protonics for fuel cells.
• Norby, Truls; Kjølseth, Christian; Strandbakke, Ragnar & Fontaine, Marie-Laure (2009). Protonics for Fuel Cells.
• Strandbakke, Ragnar & Magraso, A (2008). Electrodes.
• Kongshaug, Camilla; Strandbakke, Ragnar; Haugsrud, Reidar & Norby, Truls (2008). Presence and Charge Transport of Hydrogen-containing Species in Mayenite, Ca12Al14O33.
• Norby, Truls; Huse, Morten; Strandbakke, Ragnar; Magraso Sola, Anna & Haugsrud, Reidar (2008). Efficient and stable proton conducting SOFC (PC-SOFC) for hydrogen and reformed fossil fuels.
• Strandbakke, Ragnar; Kongshaug, Camilla; Haugsrud, Reidar & Norby, Truls (2008). High temperature hydration, conductivity and reduction of mayenite, Ca12Al14O33.
• Kongshaug, Camilla; Strandbakke, Ragnar; Haugsrud, Reidar & Norby, Truls (2008). High Temperature Transport Properties in Hydrated Mayenite, Ca12Al14O33.
• Kongshaug, Camilla & Strandbakke, Ragnar (2006). High Temperature Properties of Mayenite Ca12Al14O33.
• Abbas, Haider; Haugsrud, Reidar & Strandbakke, Ragnar (2022). Defect and transport in Ba7M’4-x MoxO20+z (M’=Nb,Ta). Universitetet i Oslo.
• Svee, Tord; Norby, Truls; Haugsrud, Reidar; Strandbakke, Ragnar; Thoreton, Vincent & Clar, Daniel (2021). Surface kinetics of BaGd1-xLaxCo2O6-𝛿 for use as an anode material in proton ceramic electrolyser cells. Universitetet i Oslo. Vis sammendrag

  The main topic of this thesis is the surface kinetics of BaGdxLa1-xCo2O6-δ (BGLC), a mixed ionic electronic conducting double perovskite, with operation temperatures between 400-700 °C that shows potential for use as an anode in Proton Conducting Ceramic Electrolysers (PCEC). While showing promise the material is still limited by its surface reactions, notably adsorption and dissociation. To test the variation in surface kinetics with the ratio of lanthanides on the A’-site, five compositions with differing lanthanide content was synthesised with a sol-gel synthesis path: BGLC19 (BaGd0.1La0.9Co2O6-δ), BGLC37 (BaGd0.3La0.7Co2O6-δ), BGLC55 (BaGd0.5La0.5Co2O6-δ), BGLC73 (BaGd0.7La0.3Co2O6-δ) and BGLC91 (BaGd0.9La0.1Co2O6-δ). Acceptable phase purity was determined through X-ray diffractometry (XRD), the batches sieved into four different grain size ranges, with diameters of 63-45 μm being used for all later experiments. Scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis were applied to examine the morphology and determine the specific surface area of the samples. Pulse isotope exchange (PIE) and gas phase analysis (GPA) were used to examine the surface kinetics of the samples. The PIE data also allows us to extract the adsorption and incorporation energy of gas species from the total activation energy. Comparative measurements in 21% oxygen at 400 °C for BGLC19 with GPA and PIE resulted in surface exchange coefficients for oxygen of 6.8×10-5 mol m-2 s -1 (PIE) and 1.3×10-5 mol m-2 s -1 (GPA), with the difference being attributed to exchange rates in GPA being limited by gas diffusion in the chamber. An experiment was also performed with PIE on BGLC19 in 21% and 2% oxygen, resulting in surface exchange coefficients of 6.8×10-5 mol m-2 s -1 (21%) and 1.2×10-4 mol m-2 s -1 (2%) at 400 °C. The total activation energy E0 for oxygen exchange was lower in 2% oxygen (0.84 eV in 2% vs 1.1 eV in 21%), but with a slightly higher adsorption energy Eads (0.79 eV in 2% vs 0.62 eV in 21%). Measurements were also performed with PIE in 2% oxygen across compositions, with BGLC55 showing the lowest incorporation energy Einc for oxygen at 0.82 eV but with the highest E0 (0.91 eV) and Eads (0.92 eV) of the set. BGLC73 displayed the lowest values for total activation and adsorption energies at 0.62 eV (E0) and 0.69 eV (Eads). The highest surface exchange rates for oxygen were measured for BGLC19, BGLC73 and BGLC91 at over 1×10-4 mol m-2 s -1 , while the values for BGLC37 and BGLC55 were around 6×10-4 mol m-2 s -1 . 3 PIE experiments involving the exchange of water vapour were also performed on BGLC37 and BGLC91, with BGLC73 exchanging the most water up to 450 °C. With unclear data and very little to no D2O measured by the mass spectrometer, these experiments remain inconclusive.

• Westvold Johansen, Hege; Haugsrud, Reidar & Strandbakke, Ragnar (2020). Defects and transport in donor doped LaNbO4. Universitetet i Oslo.
• Andersen, Håkon; Norby, Truls Eivind & Strandbakke, Ragnar (2020). Functional Properties and Electrochemical Performance of New Positrode Materials for Proton Ceramic Electrochemical Cells. Universitetet i Oslo. Vis sammendrag

  Proton Ceramic Electrochemical Cells (PCECs) exhibit high efficiency at lower temperatures due to the low activation energy ofproton transport. PCECs havealso obtained a great interest for its fuel utilisation, which result in a higher operating cell voltage and efficiency. However, the development of efficient commercial PCECs has been held back by the lack ofanefficient electrode at the oxygen steam side, also known as positrode.BaGd0.8La0.2Co2O6-δ (BGLC82) has shown to be a state of the art positrode, with Mixed Proton and Electronic Conductivity (MPEC). By using BGLC82 as a backbone in developing new and efficient electrode materials, the primary object of this thesis is to study the functional properties of selected doped BGLC82 materials, with their focus as positrodematerials for PCECs. BGLC82 was 10 % doped with the chosen materials zinc, titanium and zirconia (BaGd0.8La0.2Co1.8X0.2O6-δX=Zn, Ti, Zr). The BGLC82 compositionswere synthesised by solid-state reaction (SSR). BGLC82 Ti and Zn showed to obtain single phases, whereasBGLC82: Zr exhibit a secondary phase of BaZrO3. To try to obtain a single phase of BGLC82: Zr sol-gel (SG) synthesis was used. BGLC82: Zr still exhibited the same secondary phase obtained for SSR, but with a lower amount. This implies that the solubility of Zr in BGLC82 was exceeded.BGLC82 Ti and Zn were tested for proton uptake by Thermogravimetric Analysis (TGA)at 300 –500 °C. The measurementsshowed that BGLC82: Ti exhibitsa higher proton uptake than BGLC82, whereas BGLC82: Zn obtain lower proton uptake than BGLC82. This implies that the donor dopant stabilises the protonic defectsin the BGLC82 structure, dueto the basisety of the cation. For the experimental setup, small pellets of the BGLC82 composites were placed on top of a BaZr0.7Ce0.2Y0.1O3-δ(BZCY72) at the same time and held in place by a spring load. To obtain the best contact between the electrodes and the electrolyte, the surfaces in contact were polished. Platinumwas used as counter and reference electrode,placed on the opposite side of the BGLC82 composite electrodes.

• Pedersen, Madeeha Khalid; Norby, Truls Eivind & Strandbakke, Ragnar (2019). Fundamentals of Positrodes for Proton Ceramic Electrochemical Cells. Universitetet i Oslo.
• Emhjellen, Linn Katinka; Haugsrud, Reidar; Bjørheim, Tor Svendsen & Strandbakke, Ragnar (2017). Defects and Transport in SrFe1-xMoxO3-δ. Universitetet i Oslo.
• Prato Modestino, Rafael Albert; Haugsrud, Reidar; Strandbakke, Ragnar & Vøllestad, Einar (2016). TRANSPORT PROPERTIES AND SURFACE KINETICS OF Ba0.8+xGd0.8La0.2+xCo2O6-d. Universitetet i Oslo. Vis sammendrag

  The main topics of this thesis are the surface kinetics and bulk diffusion of oxygen in Ba(1-x)Gd0.8La(0.2+x)Co2O(6-d) (BGLC). Previous work has identified BGLC as very promising electrode material for SOFC’s and electrolyzers. With conductivities in the range of ~1000 S/cm and polarization resistances in the order of 10^-2 Ocm2 around operating temperatures (i.e. 500-700 ºC). BGLC is in line to surpass current state of the art materials. Yet in order to introduce a new electrode, thorough characterization needs to be performed on its physicochemical properties. BGLC has been identified as double perovkite (double on the c-axis) by x-ray diffractometry (XRD), and synchotron measurements, in the form of AA'B2O(6-d). Cobalt occupies the B sites at the cell’s corners, with octahedral coordination of oxygen atoms, while barium and the lanthanides occupy the center of each square cell. Such a structure is highly defective; the heterovalency between barium and the lanthanides introduces oxygen vacancies in the material. The perfect structure is defined at BaGd0.8La0.2Co2O6 in order to establish a defect model. It is suggested that cobalt ions of differing valence (+2, +3 and +4) are evenly distributed through the material, and that the oxygen sites are ordered in layers surrounding the different cations. From this starting point, effects of temperature and atmosphere on the structure and properties of BGLC is studied. High temperature in-situ XRD in the temperature range from 25 to 800 ºC shows little change in the structure. As opposed to other perovskites (ex.: GdBaCo2O6-d), BGLC remains stable through operating temperatures. Lanthanum can be used to dope the barium sites without compromising stability, leading to more compositions. Synchotron data shows the majority of oxygen vacancies aggregated in the lanthanide layer (O1 site), a reduced amount in the cobalt layer (O2 site), and no vacancies present in the barium layer (O3 site). Such a flexible structure can be reduced or oxidized easily. Changes in temperature using a thermal balance revealed the oxygen non-stoichiometry as function of temperature down to [O] ~4.9. The same experiments were performed isothermally with changing pO2. The defect model proposed is able to model the data closely for BGLC and related double perovskites. These oxygen vacancies allow for ionic diffusion through the material. The transport regimes were divided in two: surface exchange of oxigen, and bulk diffusion (self-, chemical, and tracer). Thermogravimetry (TG), isotope exchange gas phase analysis (GPA) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) were employed to measure the diffusion coefficients (D) and surface coefficient (k) of BGLC at various temperatures between 350 to 800 ºC. Dchem was measured to 10^-6 to 10^-7 cm2/s at relatively low temperatures of 600 – 500 ºC with an equally low activation energy of ~0.74 eV. This leads to an oxide ion conductivity of 10^-2 to 10^-3 S/cm at operating conditions. The values were found to be competitive with state-of-the-art materials in literature. The pre-exponential values and activation energies are in close agreement to related double perovskites such as GdBaCo2O6-d and PrBaCo2O6-d. The oxygen surface exchange was studied using GPA, where a mass spectrometer tracks the concentration of species in the gas phase of a reaction chamber. Various reaction sequences are proposed for the oxygen exchange process of adsorption-dissociation-association-desorption. The desorption/adsorption steps were found to be rate limiting for this material. The surface exchange coefficient, k, is characterized by 6.0*10^-2 Exp(-66570/RT), a high value for k0 and low Ea for perovskites, but on par with novel double-perovskites. An imporant of feature of BGLC is the relatively high proton content (~1 mol%) under wet atmosphere. The hydration properties are included and modeled in the defect structure.

• Strandbakke, Ragnar; Norby, Truls Eivind & Haugsrud, Reidar (2014). Oxygen electrodes for ceramic fuel cells with proton and oxide ion conducting electrolytes. Universitetet i Oslo.
• Sass, Tobias; Norby, Truls Eivind & Strandbakke, Ragnar (2013). Yttrium Doped Barium Zirconate: Electrical Properties and Electrodes. Universitetet i Oslo.

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