Reidar Haugsrud

• Shen, Yizhou & Haugsrud, Reidar (2025). Oxygen Surface Exchange Kinetics of Ce0.99Gd0.01O2−δ and La2Ce2O7−δ. Journal of the Electrochemical Society. ISSN 0013-4651. 172. doi: 10.1149/1945-7111/ae22e4. Full text in Research Archive Show summary

  Exploring the influence of acceptor doping on oxygen exchange is essential to utilize electrochemical transport of oxygen in ceria-based materials. Through gas phase analysis (GPA) we have elucidated the mechanism of oxygen exchange on Ce 0.99 Gd 0.01 O 2− δ and La 2 Ce 2 O 7− δ under dry and humid conditions, scenarios commonly encountered in the practical working conditions of solid oxide electrochemical cells and oxygen transport membranes. The oxygen exchange is rate-limited by the dissociation of adsorbed molecular oxygen for both materials. La 2 Ce 2 O 7− δ exhibits a higher oxygen exchange rate with lower activation energy than Ce 0.99 Gd 0.01 O 2− δ . This has been interpreted to reflect primarily higher concentration of oxygen vacancies in La 2 Ce 2 O 7− δ compared to Ce 0.99 Gd 0.01 O 2− δ . However, this increase remains moderate under conditions of relatively low electron concentration. Humidity diminishes the exchange rate due to the dissociative adsorption of water molecules into the surface oxygen vacancies, forming hydroxyl groups effectively blocking reactive sites for oxygen species.

• Shen, Yizhou & Haugsrud, Reidar (2025). Apparent non-monotonic electrical conductivity relaxation of 1 % Gd-doped ceria. Solid State Ionics. ISSN 0167-2738. 431. doi: 10.1016/j.ssi.2025.117016. Full text in Research Archive Show summary

  Steady-state and transient electrical conductivities of 1 % Gd-substituted ceria have been characterized from 550 to 800 °C under oxidizing conditions. The temperature and oxygen pressure dependencies of the steady-state conductivity resemble those of pristine ceria, with predominant n-type conductivity and some contribution of p-type conductivity under the most oxidizing conditions. Depending on temperature and oxygen partial pressure, the relaxation of the conductivity follows one-fold monotonic, two-fold monotonic, or non-monotonic behavior, despite the predominance of two charge carriers in the bulk material. Possible explanations for this peculiar phenomenon are discussed based on surface-exchange-limited oxygen exchange.

• Wen, Yabing; Rosnes, Andreas; Jiang, Bo; Prytz, Øystein; Norby, Truls & Haugsrud, Reidar [Show all 7 contributors for this article] (2025). Nickel-Induced Lattice Defects Limit Proton Uptake in Barium Zirconate Electrolytes. Journal of the American Chemical Society. ISSN 0002-7863. 148. doi: 10.1021/jacs.5c13935. Full text in Research Archive Show summary

  Nickel provides essential catalytic properties for hydrogen electrodes in proton-conducting ceramic electrochemical cells. However, Ni diminishes the hydration capability and proton conductivity when incorporated into electrolyte materials including BaZr0.8Yb0.2O3−δ studied here. Through semiquantitative atomic-resolution scanning transmission electron microscopy, density functional theory simulations, X-ray total scattering, and absorption spectroscopy, we reveal that Ni forms point defect clusters with the Yb acceptors wherein oxygen vacancies are trapped and resist hydration. The resulting effective acceptor concentration is described by point defect reactions in quantitative agreement with thermogravimetric measurements of hydration for samples substituted with 2–5 mol % Ni by BaNiO2 addition. Moreover, excess B-site cations due to NiO addition induce the formation of antiphase boundaries (APBs) that are enriched in Yb and thereby deplete the bulk of acceptors, further suppressing hydration. The adverse effects of Ni are thereby resolved into two novel mechanisms, opening new avenues in point defect engineering for high-performance electrolytes.

• Dayaghi, Amir Masoud; Almar, Laura; Escolástico, Sonia; Jiang, Bo; Carvalho, Patricia Almeida & Alfaro, Jose Manuel Serra [Show all 8 contributors for this article] (2025). On the cation distribution in acceptor doped Ba(Zr,Ce)O3 (Zr,Ce)O2 co-ionic composite electrolytes. Journal of Materials Chemistry A. ISSN 2050-7488. 13(39), p. 33528–33540. doi: 10.1039/d5ta02711j. Full text in Research Archive Show summary

  Composite co-ionic ceramic electrolytes that combine proton and oxide ion conductors hold potential for co-electrolysis of CO2 and H2O for syngas production due to flexible control of the transport numbers of the two charge carriers. Contrary to purely oxide ion co-electrolysis, co-ionic co-electrolysis embodies the supply of CO2 and H2O separately to the negative and positive electrodes, respectively. This study focuses on the development of a chemically stable co-ionic composite electrolyte of an acceptor-doped Ba(Zr,Ce)O3 proton conducting perovskite phase and an acceptor-doped (Ce,Zr)O2 oxide ion conducting fluorite phase, annealed at temperatures between 800 and 1600 °C. Comprehensive evaluations of the composites' microstructure, hydration, and conductivity were performed, revealing that annealing temperature and cation selection significantly impact the properties and performance of co-ionic electrolytes. Higher annealing temperatures drive cation redistribution, with the perovskite phase becoming zirconium-rich at its B-site and depleted in acceptor dopants, resulting in diminished hydration and protonic conductivity. Herein, we show that composites pairing cerium-rich fluorite phases (e.g., Ce0.8Gd0.2O1.9, CGO20, or Ce0.8Y0.2O1.9, CYO20) display markedly improved performance. The BaCe0.8Y0.2O2.9 (BCY20)–CYO20 system (1 : 1 weight ratio) achieved the highest conductivity (σ = 0.01 Scm−1 at 650 °C in wet Ar), establishing itself as a promising candidate for co-ionic electrolyte applications in solid oxide electrochemical cells.

• Andersen, Håkon & Haugsrud, Reidar (2025). Effects of particle size on oxygen surface exchange kinetics determined by pulse isotope exchange. Applied Surface Science. ISSN 0169-4332. 690. doi: 10.1016/j.apsusc.2025.162601. Full text in Research Archive Show summary

  Methods based on heterogeneous isotope exchange between the gas-phase and oxide surfaces have become popular experimental approaches for enhancing the fundamental understanding of rate-limiting elementary processes of the surface kinetics and developing materials with increased electrocatalytic activity towards oxygen reduction. This contribution explores the limitations of the pulse isotope exchange (PIE) technique, focusing on how particle size of the sample affects the reliability of derived kinetic parameters. Dense powders of varying particle sizes were evaluated for two materials with fundamentally different defect chemistries and transport properties: La0.6Sr0.4FeO3-δ (LSF64) and (Y2O3)0.04(ZrO2)0.96 (8-YSZ). The findings show that the ratio between the oxygen exchange and diffusion coefficients is crucial to determine the appropriate range of particle sizes that maintains the system within a kinetic regime governed by surface kinetics, adhering to the PIE approach prerequisites. If particles are too large, homoexchange and bulk diffusion can affect the measurements resulting in erroneous kinetic parameters.

• Emhjellen, Linn Katinka Susanne Shi & Haugsrud, Reidar (2025). Oxygen Exchange Across the Melting Point of V2O5–Advancing Beyond Solids? Advanced Functional Materials. ISSN 1616-301X. 35(31). doi: 10.1002/adfm.202501274. Full text in Research Archive Show summary

  Oxide melts have the potential to enhance the performance and reduce operating temperature in sustainable chemical and electrochemical technologies by improving the kinetics of the oxygen reduction reaction and oxide ion transport. This study provides the first in situ investigation of the effects of the solid-liquid phase transition on the rate of oxygen exchange for V2O5, both as single-phase material and as a component in a ZrV2O7-30mol%V2O5 composite. Upon melting of the V2O5 phase, the rate coefficients for both surface and bulk oxygen kinetics increase several orders of magnitude. The rate-determining step of the oxygen exchange reaction shifts from incorporation to dissociative adsorption. Oxygen kinetics of molten V2O5 matches, and in some cases surpasses state-of-the-art solid-state oxide-based materials. Although liquid oxide-based components may offer enhanced performance and efficiency, addressing challenges related to chemical and mechanical stability is required before application in next-generation electrochemical cells and oxygen transport membranes can be viable.

• Gudmundsdottir, Jonina Björg; Thoreton, Vincent; Jiang, Bo; Pokle, Anuj; Vøllestad, Einar & Haugsrud, Reidar [Show all 7 contributors for this article] (2025). Oxygen exchange kinetics of BaGd0.3La0.7Co2O6−δ with exsolved Co3O4 nanoparticles in dry and humid atmospheres. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 27(16), p. 8467–8477. doi: 10.1039/d4cp04791e. Full text in Research Archive Show summary

  The oxygen exchange kinetics of BaGd0.3La0.7Co2O6−δ were investigated with pulsed isotope exchange (PIE) measurements in dry and humid atmospheres in the temperature range 400–600 °C in 0.005–0.21 bar O2. Synchrotron X-ray diffraction and scanning transmission electron microscopy (STEM) revealed exsolved Co3O4 nanoparticles dispersed on the surfaces that may contribute to the catalytic activity of the material towards the oxygen exchange reactions. The obtained oxygen exchange rate was 4.45 × 10−3 mol m−2 s−1 at 600 °C in 0.21 bar O2 with an activation energy of 0.76 eV. The rate determining step of the exchange reaction was determined to be dissociative adsorption of oxygen in both dry and humid atmospheres based on the individual rates of dissociative adsorption and incorporation, as well as pO2 dependencies of the oxygen exchange rate of around 1. The effect of water on the oxygen exchange rate was found to be dependent on the oxygen partial pressure, decreasing the rate at 0.21 bar O2 and 600 °C by a factor of approx. 2, while increasing the rate at 0.02 bar and 0.005 bar O2 by a similar amount. In situ thermogravimetric analysis was used to characterise the oxygen non-stoichiometry of the material throughout the oxygen exchange measurements.

• Emhjellen, Linn Katinka Susanne Shi; Thoreton, Vincent; Xing, Wen & Haugsrud, Reidar (2025). Superior Oxygen Exchange Kinetics on Bi2O3-Based Mixed Conducting Composites. ACS Physical Chemistry Au. 5(2), p. 239–248. doi: 10.1021/acsphyschemau.4c00111. Full text in Research Archive Show summary

  The kinetics of oxygen exchange dictate the rate of redox reactions, which is crucial for electrochemical-based sustainable technologies. In this study, we use isotope exchange pulse responses to elucidate the oxygen exchange mechanism for (Bi0.8Tm0.2)2O3−δ (BTM)–(La0.8Sr0.2)0.99MnO3−δ (LSM) composites. With an optimized composition and microstructure, these composites can achieve polarization resistances below 0.01 Ω·cm2 at 700 °C. Analysis of the oxygen exchange rate, , by splitting it into elementary processes using the serial two-step scheme, demonstrates that both the dissociative adsorption and incorporation of oxygen are accelerated in BTM–LSM compared to the parent phases. Dissociative adsorption of molecular oxygen is rate-limiting below 900 °C in the range 0.002–0.05 atm O2 and below 850 °C in 0.21 atm O2. Cation interdiffusion or changes in the electronic structure at the interface between the two materials create an electrocatalytically active region spanning 1–40 nm around the BTM–LSM phase boundary. Oxygen exchange coefficients within this region were estimated to be 2–3 orders of magnitude higher compared to those of the entire composite surface. We propose two potential pathways for oxygen exchange in BTM–LSM, with calculated pO2 dependencies for each rate-determining step (rds). The pO2 dependency of reveals that molecular oxygen is involved in the rds.

• Shen, Yizhou; Thoreton, Vincent & Haugsrud, Reidar (2024). Unravelling the oxygen exchange mechanism on La2Ce2O7. Materials Advances. 6(1), p. 409–422. doi: 10.1039/d4ma00840e. Full text in Research Archive
• Dayaghi, Amir Masoud; Polfus, Jonathan M.; Strandbakke, Ragnar; Pokle, Anuj; Almar, Laura & Escolastico, Sonia [Show all 10 contributors for this article] (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. Full text in Research Archive
• Li, Zuoan & Haugsrud, Reidar (2023). Surface kinetics and bulk transport in La2Ni0.5Cu0.5O4+δ membranes from conductivity relaxation. Journal of the European Ceramic Society. ISSN 0955-2219. 43(2), p. 462–467. doi: 10.1016/j.jeurceramsoc.2022.10.046. Full text in Research Archive Show summary

  This work reports conductivity relaxation measurements on both uncoated (1.2 mm thick) and coated (2.0 mm thick) La2Ni0.5Cu0.5O4+δ membranes in the temperature range between 550-850 °C and oxygen partial pressures from 0.01 to 1.0 atm. The results show that surface kinetics has a significant effect on the relaxation profiles, especially at low temperatures and should not be neglected when extracting transport parameters. Oxygen chemical diffusion and surface exchange coefficients have been determined by transient conductivity with surface modification. Higher activation energy of surface exchange compared to bulk diffusion is observed in La2Ni0.5Cu0.5O4+δ, similar to that in La2NiO4+δ. Based on the oxygen partial pressure dependence of the surface exchange coefficient, it has been revealed that oxygen dissociative adsorption rate-limits the surface exchange.

• Emhjellen, Linn Katinka Susanne Shi; Liu, Xin; Polfus, Jonathan M. & Haugsrud, Reidar (2022). Native point defects and polaron transport in zirconium pyrovanadate. Solid State Ionics. ISSN 0167-2738. 386, p. 1–8. doi: 10.1016/j.ssi.2022.116033. Full text in Research Archive
• Emhjellen, Linn Katinka Susanne Shi; Xing, Wen; Li, Zuoan & Haugsrud, Reidar (2022). Oxygen permeability and surface kinetics of composite oxygen transport membranes based on stabilized δ-Bi2O3. Journal of Membrane Science. ISSN 0376-7388. 660, p. 1–6. doi: 10.1016/j.memsci.2022.120875. Full text in Research Archive Show summary

  Composite ceramic membranes based on the ionic conducting Tm-stabilized δ-Bi2O3 (BTM) and the electronic conducting (La0.8Sr0.2)0.99MnO3-δ (LSM) exhibit among the highest oxygen flux values reported for Bi2O3-based membranes. Here, we use pulse-response isotope exchange (PIE) and oxygen flux measurements to elaborate on limiting factors for the oxygen permeation in BTM - 40-70 vol% LSM composites. Once both phases percolate, between 30 and 50 vol% BTM, the flux is essentially independent of the BTM/LSM volume ratio. The oxygen permeability is under mixed diffusion- and surface control, gradually becoming more bulk-limited with increasing temperature. The oxygen exchange coefficients of BTM-LSM are significantly higher than its constituent phases, revealing that a cooperative surface exchange mechanism enhances the kinetics. Some of the Tm was substituted with Pr to introduce electronic conductivity in BTM. (Bi0.8Tm0.15Pr0.05)2O3-δ (BTP) exhibits higher surface exchange coefficients compared to BTM, but the oxygen flux remains one order of magnitude lower than that of percolating BTM-LSM composites.

• Hasle, Ida; Waldow, Stephan P.; Gries, Ute N.; Souza, Roger A. De; Vøllestad, Einar & Haugsrud, Reidar (2021). B-site cation inter-diffusion in yttrium substituted barium zirconate. Journal of Materials Chemistry A. ISSN 2050-7488. 9(37), p. 21142–21150. doi: 10.1039/d1ta02391h. Full text in Research Archive Show summary

  B-site cation inter-diffusion in the ABO3 perovskite yttrium-substituted barium zirconate (BZY) was studied at temperatures from 1100 to 1460 °C under reducing and oxidising conditions. The experiments followed two different approaches using Ce as a chemical tracer for Zr. By fitting diffusion profiles of the cation obtained by either Electron Probe Microanalysis (EPMA) or Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), we determined bulk, grain-boundary and effective diffusion coefficients. The activation energies of bulk diffusion (4.5 ± 0.4 eV) are similar to the migration enthalpy obtained by a computational approach (∼4 eV). On this basis, we conclude that the activation energies correspond to the migration enthalpies, assuming that the concentration of Zr vacancies in the bulk was frozen-in. Grain-boundary diffusion coefficients were found to be more than four orders of magnitude higher than the corresponding bulk values, while the activation energies of grain-boundary diffusion are relatively similar to those for bulk. This was attributed to higher concentrations of cation vacancies in space-charge layers at the boundaries. Overall, the results show that BZY electrolytes are highly stable towards degradation related to B-site cation diffusion.

• 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), p. 18537–18545. doi: 10.1039/D1TA03750A. Full text in Research Archive Show summary

  Molten-solid composite oxides are candidates as oxygen transport membranes (OTMs) at intermediate temperatures (500–700 °C). Effects of the constituent phases and interphases on surface reactions and transport processes in these composites are elusive. Here we contribute fundamental insight to such materials systems, applying electrochemical impedance spectroscopy (EIS) and electromotive force (emf) measurements to investigate the electrical conductivity characteristics of a 30 mol% V2O5–ZrV2O7 composite with a eutectic melting point at ∼670 °C. When V2O5 melts and increases the V2O5 volume percolation, the electrical conductivity increases by a factor of 10 and the activation energy increases from 0.21 to ∼0.7 eV. The oxygen red-ox reaction at the surface changes from being rate limited by charge transfer processes to mass transfer processes as a consequence of fast oxygen exchange in molten V2O5 as compared to the all-solid composite. These effects coincide with the ionic transport number rising from essentially zero to ∼0.4, reflecting a significant increase in the relative oxide ion conductivity. Oxygen permeation across a 30 mol% V2O5–ZrV2O7 membrane was estimated to be in the same order as for several dual-phase membranes, but one magnitude lower than for single-phase mixed conducting membranes at intermediate temperatures.

• 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. Full text in Research Archive Show summary

  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.

• Kalland, Liv-Elisif Queseth; Løken, Andreas; Bjørheim, Tor Svendsen; Haugsrud, Reidar & Norby, Truls Eivind (2020). Structure, hydration, and proton conductivity in 50% La and Nd doped CeO2 – La2Ce2O7 and Nd2Ce2O7 – and their solid solutions. Solid State Ionics. ISSN 0167-2738. 354. doi: 10.1016/j.ssi.2020.115401. Full text in Research Archive Show summary

  We have measured water uptake and hydration enthalpy in 50% La and Nd doped CeO2, also to be taken as compositions in the series La2−xNdxCe2O7 (x = 0.0, 0.5, 1.0 and 2.0) using combined thermogravimetry (TG) and differential scanning calorimetry (DSC), TG-DSC. The TG-DSC data unambiguously yield standard molar hydration enthalpies of ~−74 kJ/mol independent of water uptake. The interpretation of the TG results, however, does not fit a classical model of hydration of all oxygen vacancies. Instead, the hydration appears to be limited to a small fraction of the free vacancies. Hydration further decreases as the Nd content (x) and long-range order increases and regions of disorder decrease. We propose a new model explaining why hydration occurs only in a small fraction of the nominally free vacancies: The higher basicity of La/Nd compared to Ce promotes protonation at oxide ion sites with high coordination to La/Nd, and the observed water uptake and modelling suggests that mainly oxide ions fully coordinated to 4 La/Nd neighbours become protonated. The statistical variation of coordination around oxygen sites in a disordered fluorite oxide creates a limited number of such oxide ions sites which results in limited hydration. The model matches well the experimental results and DFT calculations of proton trapping at the fully La-coordinated sites for 50% La-doped CeO2, and also rationalizes conductivity data.

• Stefan, Elena; Denonville, Christelle; Larring, Yngve; Stange, Marit Synnøve Sæverud & Haugsrud, Reidar (2019). Oxidation study of porous metal substrates for metal supported proton ceramic electrolyzer cells. Corrosion Science. ISSN 0010-938X. 164. doi: 10.1016/j.corsci.2019.108335. Full text in Research Archive
• Stange, Marit Synnøve Sæverud; Dayaghi, Amir Masoud; Denonville, Christelle; Larring, Yngve; Rørvik, Per Martin & Haugsrud, Reidar [Show all 7 contributors for this article] (2019). Fabrication of metal-supported proton-conducting electrolysers with thin film Sr- And Ce-doped BZY electrolyte. ECS Transactions. ISSN 1938-5862. 91(1), p. 941–949. doi: 10.1149/09101.0941ecst. Full text in Research Archive Show summary

  n this work, we present fabrication and initial testing of metal-supported proton ceramic electrolyser (MS-PCEC) single cells with a thin electrolyte. Plansee ITM porous metal is used as metal support. Spray-coating is used to deposit a conducting layer of La1-xSrxTi1-yNiyO3-δ (LSTN) which is used for low temperature (600-800 °C) deposition of a gas-tight, thin-film layer (~2 μm) of electrolyte by pulsed laser deposition (PLD). Post-annealing of the electrolyte is evaluated to improve its performance. In order to have a smaller thermal expansion coefficient (TEC) mismatch towards LSTN (~10-11 × 10-6 K-1), we developed a new Sr- and Ce-doped proton-conducting electrolyte, yielding a larger TEC (~10-11 × 10-6 K-1) compared to BZY (~8 × 10-6 K-1). The cell with Pt as air electrode shows acceptable open circuit voltage and low overpotentials at 600 °C, demonstrating the potential of developing the first working MS-PCEC.

• Liu, Xin; Bjørheim, Tor Svendsen; Vines, Lasse; Fjellvåg, Øystein; Granerød, Cecilie Skjold & Prytz, Øystein [Show all 10 contributors for this article] (2019). Highly Correlated Hydride Ion Tracer Diffusion in SrTiO3–xHx Oxyhydrides. Journal of the American Chemical Society. ISSN 0002-7863. 141(11), p. 4653–4659. doi: 10.1021/jacs.8b12985. Full text in Research Archive Show summary

  Mixed oxide hydride anion systems constitute a novel class of materials exhibiting intriguing properties such as solid-state hydride ion conduction and fast anion exchange. In this contribution we derive the kinetics of hydride ion transport in a mixed oxide–hydride system, SrTiO3–xHx, through isotope exchange and depth profiling. Density functional theory (DFT) calculations indicate that migration of H– to neighboring vacant oxygen lattice sites is fast, but that long-range transport is impeded by slow reorganization of the oxygen sublattice. From measured hydride tracer-diffusion coefficients and the correlation factors derived from DFT, we are able to derive the hydrogen self-diffusion coefficients in SrTiO3–xHx. More generally, the explicit description of hydride ion transport in SrTiO3–xHx through combination of experimental and computational methods reported in this work can be applied to explore anion diffusion in other mixed anion systems.

• Desissa, Temesgen D.; Haugsrud, Reidar; Wiik, Kjell & Norby, Truls Eivind (2018). Inter-diffusion across a direct p-n heterojunction of Li-doped NiO and Al-doped ZnO. Solid State Ionics. ISSN 0167-2738. 320, p. 215–220. doi: 10.1016/j.ssi.2018.03.011. Full text in Research Archive Show summary

  We herein report inter-diffusion across the interface between p-type Ni0.98Li0.02O and n-type Zn0.98Al0.02O for various applications including p-n-heterojunction diodes and oxide thermoelectrics. Diffusion couples were made of polished surfaces of ceramic samples pre-sintered at 1250 and 1350 °C for Ni0.98Li0.02O and Zn0.98Al0.02O, respectively. The inter-diffusion couples were annealed at 900–1200 °C for 160 h in ambient air. Electron Probe Micro Analysis (EPMA) was used to acquire diffusion profiles, followed by fitting to Fick's second law and Whipple–Le Claire's models for bulk and grain-boundary diffusion calculation, respectively. Zn2+ diffused into Ni0.98Li0.02O mainly by bulk diffusion with an activation energy of 250 ± 10 kJ/mol, whereas Ni2+ diffused into Zn0.98Al0.02O by both bulk and enhanced grain boundary diffusion with activation energies of 320 ± 120 kJ/mol and 245 ± 50 kJ/mol, respectively. The amount of Al3+ diffused from the Al-doped ZnO into the NiO phase was too small for a corresponding diffusion coefficient to be calculated. Li-ion distribution and diffusivity were not determined due to lack of analyzer sensitivity for Li. The bulk and effective diffusivities of Zn2+ and Ni2+ into NiO and ZnO enable prediction of inter-diffusion lengths as a function of time and temperature, allowing estimates of device performance, stability, and lifetimes at different operation temperatures.

• Liu, Xin; Bjørheim, Tor Svendsen & Haugsrud, Reidar (2018). Formation of defects and their effects on hydride ion transport properties in a series of K2NiF4-type oxyhydrides. Journal of Materials Chemistry A. ISSN 2050-7488. 6(4), p. 1454–1461. doi: 10.1039/c7ta08435h. Full text in Research Archive
• Stefan, Elena; Stange, Marit Synnøve Sæverud; Denonville, Christelle; Larring, Yngve; Hildenbrand, Nicolas & Norby, Truls Eivind [Show all 7 contributors for this article] (2017). Layered microstructures based on BaZr0.85Y0.15O3−δ by pulsed laser deposition for metal-supported proton ceramic electrolyser cells. Journal of Materials Science. ISSN 0022-2461. 52(11), p. 6486–6497. doi: 10.1007/s10853-017-0884-1. Full text in Research Archive Show summary

  Planar metal-supported cell designs provide cost-effective scaling-up of solid oxide fuel cells and electrolysers. Here, we report on the fabrication of a BaZr0.85Y0.15O3−δ–NiO (BZY15–NiO) composite electrode and BaZr0.85Y0.15O3−δ (BZY15) proton-conducting electrolyte films on metal and ceramic substrates using pulsed laser deposition (PLD). The results demonstrate successful sequential deposition of porous electrode and dense electrolyte structure by PLD at moderate temperatures, without the need for subsequent high-temperature sintering. The decrease in roughness of the metal substrate used for deposition by spray-coating intermediary oxide layers had significant importance to the fabrication of functional layers as thin films. Crystalline porous BZY15–NiO and dense BZY15 films were sequentially deposited at high substrate temperature on metal supports (MS) with or without an electron-conducting barrier oxide layer, e.g. MS/(BZY15–Ni)/(BZY15–NiO)/BZY15 and MS/CeO2/(BZY15–NiO)/BZY15. The different microstructures for electrode and electrolyte were achieved with deposition steps at different substrate temperatures (800, 600 °C) and a gradual decrease in the pressure of O2 in the deposition chamber.

• Malerød-Fjeld, Harald; Clark, Daniel Ryan; Yuste-Tirados, Irene; Zanón, Raquel; Catalán-Martinez, David & Beeaff, Dustin [Show all 12 contributors for this article] (2017). Thermo-electrochemical production of compressed hydrogen from methane with near-zero energy loss. Nature Energy. 2(12), p. 923–931. doi: 10.1038/s41560-017-0029-4. Full text in Research Archive
• Sazinas, Rokas; Sakaguchi, Isao; Hasle, Ida Margrete; Polfus, Jonathan M.; Haugsrud, Reidar & Einarsrud, Mari-Ann [Show all 7 contributors for this article] (2017). Tracer diffusion of 96Zr and 134Ba in polycrystalline BaZrO3. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 19(32), p. 21878–21886. doi: 10.1039/C7CP04039C. Full text in Research Archive Show summary

  Cation tracer diffusion in polycrystalline cubic BaZrO3 perovskites was studied using the stable isotopes 134Ba and 96Zr in air at 1015–1200 and 1300–1500 °C, respectively. Thin films of 134BaO and 96ZrO2 were deposited on polished BaZrO3 pellets by drop casting of aqueous precursor solutions containing the tracers. Isotope distribution profiles were recorded using secondary ion mass spectrometry. All the depth profiles exhibited two distinct regions, which enabled the assessment of both lattice and grain boundary diffusion using Fick's second law and Whipple–Le Clair's equation. The grain boundary diffusion of both cations was several orders of magnitude higher than the lattice diffusion. The lattice diffusion of Ba2+ was found to be significantly faster than the lattice diffusion of Zr4+, while the activation energies were comparable, respectively 395 ± 44 and 435 ± 67 kJ mol−1. Activation energies for the diffusion of Ba2+ and Zr4+ through a Ba2+ vacancy were calculated by density functional theory using the nudged elastic band method. The calculated and experimental activation energies were in excellent agreement. The cation diffusion data in BaZrO3 are compared to previous data on A and B-site diffusivity in perovskites. Finally, the diffusivity of Zr4+ in compounds with perovskite and fluorite crystal structures is discussed in relation to the chemical stability of BaZrO3-based materials.

• Escolastico, S; Solis, C; Haugsrud, Reidar; Magraso, Anna & Serra, J. M. (2017). On the ionic character of H2 separation through mixed conducting Nd5.5W0.5Mo0.5O11.25−δ membrane. International Journal of Hydrogen Energy. ISSN 0360-3199. 42(16), p. 11392–11399. doi: 10.1016/j.ijhydene.2017.02.087. Full text in Research Archive
• Hancke, Ragnhild & Haugsrud, Reidar (2017). The correlation between surface kinetic and bulk diffusion properties of proton conducting oxides. Solid State Ionics. ISSN 0167-2738. 306, p. 48–54. doi: 10.1016/j.ssi.2017.02.006. Full text in Research Archive
• Liu, Xin; Bjørheim, Tor Svendsen & Haugsrud, Reidar (2017). Formation and migration of hydride ions in BaTiO3-xHx oxyhydride. Journal of Materials Chemistry A. ISSN 2050-7488. 5(3), p. 1050–1056. doi: 10.1039/c6ta06611a. Full text in Research Archive
• Stange, Marit Synnøve Sæverud; Stefan, Elena; Denonville, Christelle; Larring, Yngve; Rørvik, Per Martin & Haugsrud, Reidar (2017). Development of novel metal-supported proton ceramic electrolyser cell with thin film BZY15–Ni electrode and BZY15 electrolyte. International Journal of Hydrogen Energy. ISSN 0360-3199. 42(19), p. 13454–13462. doi: 10.1016/j.ijhydene.2017.03.028. Full text in Research Archive Show summary

  Metal supports for planar MS-PCEC were manufactured using tape-casting of low-cost ferritic stainless steel. A coating protecting the metal support against oxidation was applied by vacuum infiltration and a buffer layer of La0.5Sr0.5Ti0.75Ni0.25O3–δ (LSTN) was further deposited to smoothen the surface. The BaZr0.85Y0.15O3–δ–NiO (BZY15–NiO) cathode and the BaZr0.85Y0.15O3–δ (BZY15) electrolyte were applied by pulsed laser deposition (PLD) at elevated substrate temperatures (at 700 °C and 600 °C, respectively). The main challenges are related to the restrictions in sintering temperature and atmosphere induced by the metal support, as well as strict demands on the roughness of substrates used for PLD. Reduction treatment of the half cells confirmed that NiO in the BZY15–NiO layer was reduced to Ni, resulting in increased porosity of the BZY15–Ni cathode, while keeping the columnar and dense microstructure of the BZY15 electrolyte. Initial electrochemical testing with a Pt anode showed a total resistance of 40 Ω·cm2 at 600 °C. Through this work important advances in using metal supports and thin films in planar PCEC assemblies have been made.

• Cao, Yong; Xiong, Chunyan; Jian, Li; Vøllestad, Einar; Evans, Anna & Haugsrud, Reidar (2016). Enhancement of the electron conductivity of La27(W0.85Nb0.15)5O55.5-δ by Mo doping for hydrogen permeation. Journal of the Electrochemical Society. ISSN 0013-4651. 163(10), p. F1151–F1156. doi: 10.1149/2.1251609jes. Full text in Research Archive
• Bjørheim, Tor Svendsen; Løken, Andreas & Haugsrud, Reidar (2016). On the relationship between chemical expansion and hydration thermodynamics of proton conducting perovskites. Journal of Materials Chemistry A. ISSN 2050-7488. 4(16), p. 5917–5924. doi: 10.1039/c5ta10090a. Full text in Research Archive Show summary

  In this contribution, we determine the compositional dependence of the chemical expansion and entropy of hydration of the proton conducting perovskites BaZrO3, BaSnO3, BaCeO3, and SrZrO3 by first principles phonon calculations. The calculations reveal that the cubic BaZrO3 and BaSnO3, which display the least favourable hydration enthalpies, −72 and −65 kJ mol−1, respectively, exhibit the most favourable entropies, −108 and −132 J mol−1 K−1, respectively. The strong compositional dependency of the hydration entropy primarily originates from the entropy gain upon filling the oxygen vacancy, which is closely related to the chemical expansion coefficient of oxygen vacancies, and thus the chemical expansion upon hydration. The chemical expansion coefficient of oxygen vacancies is more negative for the cubic than the orthorhombic perovskites, leading to a considerably larger chemical expansion upon hydration of the former. The calculations therefore suggest that challenges associated with chemical expansion upon hydration of BaZrO3 proton conducting electrolytes to some extent can be avoided, or reduced, by partial substitution of Zr by Ce.

• Wachowski, Sebastian Lech; Mielewczyk-Gryn, Aleksandra; Zagorski, Krzysztof; Li, Cheng; Jasinski, Piotr & Skinner, Stephen J [Show all 8 contributors for this article] (2016). Influence of Sb-substitution on ionic transport in lanthanum orthoniobates. Journal of Materials Chemistry A. ISSN 2050-7488. 4(30), p. 11696–11707. doi: 10.1039/c6ta03403a. Full text in Research Archive
• Løken, Andreas; Haugsrud, Reidar & Bjørheim, Tor Svendsen (2016). Unravelling the fundamentals of thermal and chemical expansion of BaCeO3 from first principles phonon calculations. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 18(45), p. 31296–31303. doi: 10.1039/C6CP05710A. Full text in Research Archive Show summary

  Differentiating chemical and thermal expansion is virtually impossible to achieve experimentally. While thermal expansion stems from a softening of the phonon spectra, chemical expansion depends on the chemical composition of the material. In the present contribution, we, for the first time, completely decouple thermal and chemical expansion through first principles phonon calculations on BaCeO3, providing new fundamental insights to lattice expansion. We assess the influence of defects on thermal expansion, and how this in turn affects the interpretation of chemical expansion and defect thermodynamics. The calculations reveal that the linear thermal expansion coefficient is lowered by the introduction of oxygen vacancies being 10.6 × 10−6 K−1 at 300 K relative to 12.2 × 10−6 K−1 for both the protonated and defect-free bulk lattice. We further demonstrate that the chemical expansion coefficient upon hydration varies with temperature, ranging from 0.070 to 0.115 per mole oxygen vacancy. Ultimately, we find that, due to differences in the thermal expansion coefficients under dry and wet conditions, the chemical expansion coefficients determined experimentally are grossly underestimated – around 55% lower in the case of 10 mol% acceptor doped BaCeO3. Lastly, we evaluate the effect of these volume changes on the vibrational thermodynamics.

• Skomedal, Gunstein; Burkov, Alexander; Samunin, Alexander Yu; Haugsrud, Reidar & Middleton, Peter Hugh (2016). High temperature oxidation of Mg2(Si-Sn). Corrosion Science. ISSN 0010-938X. 111(1), p. 325–333. doi: 10.1016/j.corsci.2016.05.016. Full text in Research Archive
• Cao, Yong; Duan, Nanqi; Jian, Li; Evans, Anna & Haugsrud, Reidar (2016). Effect of Nb Doping on Hydration and Conductivity of La27W5O55.5. Journal of The American Ceramic Society. ISSN 0002-7820. 99(10), p. 3309–3316. doi: 10.1111/jace.14346. Full text in Research Archive
• Liu, Xin; Bjørheim, Tor Svendsen & Haugsrud, Reidar (2016). Thermochemical properties of rare-earth oxyhydrides from first principles phonon calculations. RSC Advances. 6(12), p. 9822–9826. doi: 10.1039/c5ra26552e. Full text in Research Archive

View all works in NVA

• Gudmundsdottir, Jonina Björg; Haugsrud, Reidar; Vøllestad, Einar & Polfus, Jonathan (2024). Oxygen Exchange Kinetics of BaGd0.3La0.7Co26-d Air/Steam Electrode for Proton Ceramic Electrochemical Cells. Full text in Research Archive
• Gudmundsdottir, Jonina Björg; Haugsrud, Reidar; Vøllestad, Einar & Polfus, Jonathan (2024). Oxygen Exchange Kinetics of BaGd0.3La0.7Co2O6-d Air/Steam Electrode for Proton Ceramic Electrochemical Cells. Full text in Research Archive
• Andersen, Håkon; Larring, Yngve & Haugsrud, Reidar (2024). Kinetic study of novel oxygen carriers for chemical looping for hydrogen production: Ca0.6La0.4Ti0.1CrxMn0.9-xO3-δ (x = 0, 0.3, 0.45, 0.6 & 0.9). Full text in Research Archive
• Andersen, Håkon; Larring, Yngve & Haugsrud, Reidar (2024). Kinetic study of novel oxygen carriers for chemical looping for hydrogen production: Ca0.6La0.4Ti0.1CrxMn0.9-xO3-δ (x = 0.3, 0.45 & 0.6). Full text in Research Archive
• Gudmundsdottir, Jonina Björg; Vøllestad, Einar; Haugsrud, Reidar & Polfus, Jonathan (2023). Oxygen Exchange Kinetics of BaGd0.3La0.7Co2O6-d. Full text in Research Archive
• Andersen, Håkon; Larring, Yngve & Haugsrud, Reidar (2023). Particle size effects on pulse isotope exchange measurements. Full text in Research Archive
• Xing, Wen; Emhjellen, Linn Katinka Susanne Shi; Haugsrud, Reidar & Li, Zuoan (2022). Ceramic composite oxygen transport membranes based on stabilised Bi2O3. Full text in Research Archive
• Thoreton, Vincent & Haugsrud, Reidar (2022). Surface Exchange Study of Proton Ceramic Electrochemical Cell’s Positrode by Gas Phase. Full text in Research Archive
• Stange, Marit Synnøve Sæverud; Denonville, Christelle; Stefan, Elena; Dayaghi, Amir Masoud; Larring, Yngve & Rørvik, Per Martin [Show all 9 contributors for this article] (2022). Fabrication and testing of thin-film based metal-supported proton ceramic electrochemical cells. Full text in Research Archive
• 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. Full text in Research Archive
• Stange, Marit Synnøve Sæverud; Stefan, Elena; Dayaghi, Amir Masoud; Denonville, Christelle; Larring, Yngve & Rørvik, Per Martin [Show all 8 contributors for this article] (2021). Pulsed Laser Deposition of Electrolytes for Metal-Supported Proton-Conducting Electrolysis Cells. Full text in Research Archive
• Norby, Truls; Dayaghi, Amir Masoud; Storhaug, Sjur; Chen, Henry; Haugsrud, Reidar & Stange, Marit Synnøve Sæverud [Show all 9 contributors for this article] (2021). BSZCY151020: A proton ceramic electrolyte with increased TEC for planar applications. Full text in Research Archive
• Stange, Marit Synnøve Sæverud; Stefan, Elena; Denonville, Christelle; Dayaghi, Amir Masoud; Larring, Yngve & Rørvik, Per Martin [Show all 11 contributors for this article] (2021). Processing route for Metal Supported Proton Conducting Ceramic Cells. Full text in Research Archive
• Thoreton, Vincent; Liu, Xin; Li, Zuoan & Haugsrud, Reidar (2021). Effect of water vapour on the oxygen surface exchange kinetics of CaTi0.9Fe0.1O3-δ. Full text in Research Archive
• Thoreton, Vincent; Liu, Xin; Li, Zuoan; Bjørheim, Tor Svendsen & Haugsrud, Reidar (2020). Surface exchange kinetics of CaTi0.9Fe0.1O3-δ. Full text in Research Archive
• Stange, Marit Synnøve Sæverud; Dayaghi, Amir Masoud; Denonville, Christelle; Larring, Yngve; Rørvik, Per Martin & Haugsrud, Reidar [Show all 7 contributors for this article] (2019). Key challenges in fabrication of metal-supported thin film proton conducting electrolyser cells. Full text in Research Archive
• Stange, Marit Synnøve Sæverud; Dayaghi, Amir Masoud; Denonville, Christelle; Larring, Yngve; Rørvik, Per Martin & Haugsrud, Reidar [Show all 7 contributors for this article] (2019). Fabrication of Metal-Supported Proton-Conducting Electrolysers with Thin Film Sr- and Ce-Doped BZY Electrolyte. Full text in Research Archive
• Dayaghi, Amir Masoud; Stange, Marit Synnøve Sæverud; Denonville, Christelle; Larring, Yngve; Rørvik, Per Martin & Haugsrud, Reidar [Show all 7 contributors for this article] (2019). Thin-film electrolyte with TEC optimized for metal-supported proton ceramic electrochemical cell. Full text in Research Archive
• Thoréton, Vincent; Bjørheim, Tor Svendsen; Liu, Xin; Li, Zuoan & Haugsrud, Reidar (2019). Influence of water vapour on the surface exchange kinetics of functional oxides. Full text in Research Archive
• Norby, Truls Eivind; Liu, Xin; Bjørheim, Tor Svendsen & Haugsrud, Reidar (2019). Hydride ion conduction. Full text in Research Archive
• Norby, Truls Eivind; Kalland, Liv-Elisif Queseth; Løken, Andreas; Bjørheim, Tor Svendsen & Haugsrud, Reidar (2019). Hydration of fluorite-related rare-earth cerates. Full text in Research Archive
• Emhjellen, Linn Katinka; Xing, Wen; Li, Zuoan & Haugsrud, Reidar (2019). Electrochemical Transport in Molten/Solid Composite V2O5-ZrV2O7. Full text in Research Archive
• Li, Zuoan; Liu, Xin & Haugsrud, Reidar (2019). Dissociation of oxygen on oxides determined by a modified gas phase analysis (GPA). Full text in Research Archive
• Clark, Daniel Ryan; Malerød-Fjeld, Harald; Budd, Michael; Catalán-Martinez, David; Beeaff, Dustin & Norby, Truls Eivind [Show all 7 contributors for this article] (2018). Design and development of next-generation protonic reactors. Full text in Research Archive
• Haugsrud, Reidar; Chen, Min & Bjørheim, Tor Svendsen (2017). SSPC-18 Conference Special Issue. Solid State Ionics. ISSN 0167-2738. 306, p. 1–1. doi: 10.1016/j.ssi.2017.04.012. Full text in Research Archive
• Stange, Marit Synnøve Sæverud; Denonville, Christelle; Larring, Yngve; Stefan, Elena; Rørvik, Per Martin & Haugsrud, Reidar [Show all 7 contributors for this article] (2017). Manufacturing of Metal Supported Protonic Ceramic Electrolyser Cells (PCEC). Full text in Research Archive
• Clark, Daniel Ryan; Kjølseth, Christian; Malerød-Fjeld, Harald; Morejudo, Selene Hernandez; Zanon, R. & Serra, J [Show all 11 contributors for this article] (2017). Intensified Conversion of Natural Gas Using Proton-Conducting Ceramics. Full text in Research Archive
• Li, Zuoan & Haugsrud, Reidar (2017). Oxygen dissociation rate of oxide ion conductors determined by a novel gas phase analysis technique. Full text in Research Archive
• Løken, Andreas; Bjørheim, Tor Svendsen & Haugsrud, Reidar (2016). The detrimental role of acceptor and oxygen vacancy clustering on the hydration and transport properties of proton conducting oxides. Full text in Research Archive
• Stange, Marit Synnøve Sæverud; Stefan, Elena; Denonville, Christelle; Larring, Yngve; Rørvik, Per Martin & Fontaine, Marie-Laure [Show all 7 contributors for this article] (2016). Development of metal supported proton ceramic electrolyser cells (PCEC) for renewable hydrogen production. Full text in Research Archive
• Stange, Marit Synnøve Sæverud; Stefan, Elena; Denonville, Christelle; Fontaine, Marie-Laure; Larring, Yngve & Haugsrud, Reidar (2016). Development of metal supported proton ceramic electrolyser cells (PCEC) for renewable hydrogen production. Full text in Research Archive
• Stange, Marit Synnøve Sæverud; Stefan, Elena; Denonville, Christelle; Larring, Yngve & Haugsrud, Reidar (2016). DEVELOPMENT OF MS-PCEC. Full text in Research Archive
• Liu, Xin; Bjørheim, Tor Svendsen & Haugsrud, Reidar (2016). Hydride migration and electron localization in BaTiO3-xHx oxyhydride. Full text in Research Archive
• Stange, Marit Synnøve Sæverud; Stefan, Elena; Denonville, Christelle; Larring, Yngve; Rørvik, Per Martin & Haugsrud, Reidar (2016). Progress on development of metal-supported proton conducting electrolysis cells (PCEC). Full text in Research Archive
• Hasle, Ida Margrete; Vøllestad, Einar; Haugsrud, Reidar; Souza, Roger De; Gries, Ute & Waldow, Stephan (2016). B-site Cation (Zr4+) Diffusion in Yttrium doped Barium Zirconate. Full text in Research Archive
• Stefan, Elena; Stange, Marit Synnøve Sæverud; Denonville, Christelle; Larring, Yngve; Norby, Truls & Haugsrud, Reidar (2016). Fabrication of Multi-layered Microstructures based on BaZr0.85Y0.15O3-δ for Metal Supported Proton Ceramic Electrolyzer Cells by Pulsed Laser Deposition. Full text in Research Archive
• Hasle, Ida Margrete; Haugsrud, Reidar & Polfus, Jonathan M. (2016). Computational Studies of Cation Transport in Barium Zirconate. Full text in Research Archive
• 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. Full text in Research Archive
• Løken, Andreas; Olsen, Malin Solheim; Bjørheim, Tor Svendsen & Haugsrud, Reidar (2016). The Effect of Clustering of Acceptors and Oxygen Vacancies on the Hydration and Transport of Proton Conducting Oxides. Full text in Research Archive
• Løken, Andreas; Haugsrud, Reidar & Bjørheim, Tor Svendsen (2016). Unravelling the Fundamentals of Thermal and Chemical Expansion of Proton Conducting Oxides. Full text in Research Archive
• Stange, Marit Synnøve Sæverud; Denonville, Christelle; Stefan, Elena; Haugsrud, Reidar; Rørvik, Per Martin & Larring, Yngve (2015). Development of thin film based metal supported PCEC. Full text in Research Archive
• Stefan, Elena; Stange, Marit Synnøve Sæverud; Denonville, Christelle; Larring, Yngve; Dahl-Hansen, Runar & Rørvik, Per Martin [Show all 8 contributors for this article] (2015). Electrode and Electrolyte Microstructures based on BaZr0.85Y0.15O3-δ for Proton Ceramic Electrolyzer Cells by Pulsed Laser Deposition. Full text in Research Archive
• Stefan, Elena; Stange, Marit Synnøve Sæverud; Denonville, Christelle; Larring, Yngve; Dahl-Hansen, Runar & Rørvik, Per Martin [Show all 8 contributors for this article] (2015). Characterization of BaZr0.85Y0.15O3-δ Thin Films for Proton Ceramic Electrolyzer Cells by Pulsed Laser Deposition. Full text in Research Archive
• Stefan, Elena; Stange, Marit Synnøve Sæverud; Denonville, Christelle; Dahl-Hansen, Runar; Larring, Yngve & Rørvik, Per Martin [Show all 9 contributors for this article] (2015). Fabrication and Characterization of Metal Supported Proton Ceramic Electrolyzer Cells (PCEC). Full text in Research Archive
• Lervik, Adrian; Haugsrud, Reidar; Diplas, Spyridon & Gunnæs, Anette Eleonora (2015). A TEM approach to BZY. Full text in Research Archive
• Fjellvåg, Øystein Slagtern; Sjåstad, Anja Olafsen; Haugsrud, Reidar & Gunnæs, Anette Eleonora (2015). Investigation of Novel Hydride Oxides for Holistic Understanding of Functional Materials. Full text in Research Archive
• Emhjellen, Linn Katinka Susanne Shi; Haugsrud, Reidar & Bjørheim, Tor Svendsen (2025). Oxygen transport and surface kinetics in molten and solid composites. Universitetet i Oslo. Full text in Research Archive Show summary

  Oxygen-permeable ceramics are essential for gas separation and electrochemical technologies, including applications in the steel and chemical industries, as well as in low-carbon or clean energy systems such as oxyfuel combustion and solid oxide fuel cells. However, slow oxygen reduction and evolution at the surfaces often hinder the development of these materials, highlighting the need for a deeper understanding of reaction pathways and rate-limiting steps in the oxygen exchange mechanism. This work demonstrates the notable oxygen flux and surface kinetics of Tm-doped Bi2O3- (BTM) and (La0.8Sr0.2)0.99MnO3-δ (LSM) composites - on par with state-of-the art oxygen permeable membranes - and offers fundamental insights into the surface processes in mixed-conducting dual-phase materials. Furthermore, oxide melts - with their lower activation barriers for oxygen transport and kinetics - are promising candidates for operation at intermediate temperatures. The literature on oxygen transport in melts is limited, and on surface kinetics, virtually non-existent. We present the first in-situ investigation of oxygen transport and surface exchange across the solid-liquid transition in V2O5, both as a single-phase material and as part of a ZrV2O7-30mol%V2O5 composite. Reaction rates increase by several orders of magnitude during the melting of V2O5.

• Storhaug, Sjur; Haugsrud, Reidar & Norby, Truls (2022). Sintering and electrical properties of proton conducting BSZCY151020. Universitetet i Oslo. Full text in Research Archive
• Abbas, Haider; Haugsrud, Reidar & Strandbakke, Ragnar (2022). Defect and transport in Ba7M’4-x MoxO20+z (M’=Nb,Ta). Universitetet i Oslo. Full text in Research Archive
• Chen, Henry; Norby, Truls; Haugsrud, Reidar & Dayaghi, Amir Masoud (2022). Sintering Behavior and Conductivity of (Ba0.85Sr0.15)(Zr0.7Ce0.1Y0.2)O3-δ Doped with ZnO as Sintering Aid. Universitetet i Oslo. Full text in Research Archive
• Mäntysalo, Visa Aleksi & Haugsrud, Reidar (2021). Synthesis and Characterization of La4BaCu5-xCoxOα as a Positrode for Proton Ceramic Electrochemical Cells - An Experimental and First Principles Investigation. Universitetet i Oslo. Full text in Research Archive
• 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. Full text in Research Archive Show summary

  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.

• Alsgaard, Erik Erlend Pham; Norby, Truls; Haugsrud, Reidar & Bjørheim, Tor Svendsen (2021). Protonic Transport Properties of Perovskite Heterostructures. Universitetet i Oslo. Full text in Research Archive Show summary

  Proton ceramic fuel cells based on an yttrium-doped barium zirconate electrolyte might pose as a viable option for future hydrogen applications. High resistances in the electrolyte however hampers the performance of the material. Therefore, a novel heterostructure engineering strategy is applied in order to investigate alternative solutions to reducing the resistances. This thesis aims to deepen our understanding of how heterostructures and their interfaces might affect the electrolyte resistances. The goal of the following approach is to circumvent proton trapping at acceptor dopant sites. A job-sharing model has been investigated where one phase “supplies” the protons while the other phase conducts them. The proton donor phase is acceptor doped and more acidic than the other phase, resulting in a net transfer of protons over to the conductive phase. The latter phase, free of trap sites and enriched in charge carriers, is then hypothesized to exhibit a conductivity increase. Modern computational methods allow for compositions to be investigated theoretically without having to perform tedious experiments. While experiments measure the actual effects of the system of interest, the results might be ambiguous as they often are a combination of several contributions. Theoretical computations on the other hand might give insight into trends, often on the atomistic scale, else impossible to separate from other effects experimentally. Combining the two methods, in depth knowledge and understanding of the system is acquirable. The model system, an alternating multi layered BaZr1-xYxO3/SrTi1-xScxO3 film was fabricated by pulsed laser deposition onto a (100) MgO substrate. The thin (60 nm) films were by X-ray diffraction confirmed to be grown epitaxially, made possible by a good lattice match between the substrate and the films. Impedance spectroscopy measurements of the BaZrO3/SrTi0.9Sc0.1O3 film showed a conductivity of 0.27 mS/cm, comparable to the conductivity of the reference BaZr0.9Y0.1O3 film (0.28 mS/cm). The activation energy of the heterostructure was measured to 0.45 eV, lower than for the reference BaZrO3 and BaZr0.9Y0.1O3 films and in the range of the proton migration activation energy. The SrTi0.9Sc0.1O3 had a larger activation energy of 0.64 eV, expected for oxide ion conduction mechanism. VII When going to dry from humid atmosphere for the BaZr1-xYxO3 containing films was a decrease in conductivity of 55 % to 65 %, attributed to a decrease in charge carrier (proton) concentrations which was further confirmed by a hydrogen isotope exchange. A slope of 0.143 was observed in the Arrhenius plot of the SrTi0.9Sc0.1O3 film, indicating that ionic defects dominate concentration-wise whilst minority holes contribute significantly to the conductivity in the measured pO2 range. First principles calculations of a BaZr0.984Y0.016O3H0.016 4 by 4 supercell showed the energy difference a at set of Y-H + distances. The trapping energy of the protons was calculated as a function of in-plane strain and was found to increase with more negative (compressive) strain. Additionally, strain in general decreases the long-range mobility of protons in the yttrium dopants because of an energy barrier, larger than or equal to the trapping energy. Removing -0.5 % of strain was found to result in an activation energy decrease, increasing the conductivity by a factor of two. The calculated trapping energy change for different levels of strain agree well with experimental activation energies from literature [1]. Comparisons of measurements between reference films and the BaZrO3/SrTi0.9Sc0.1O3 heterostructure supports the job-sharing model. By assuming that the space charge region of the BaZrO3 and SrTi0.9Sc0.1O3 does not affect the conductivity of the latter, a conductivity increase of a factor of 14 was calculated for the BaZrO3 layer of the heterostructure compared to the reference BaZrO3 film.

• Kalland, Liv-Elisif Queseth; Norby, Truls Eivind; Mohn, Chris Erik & Haugsrud, Reidar (2021). Ab initio modelling and experimental studies of order-disorder, hydration, and ionic conductivity of fluorite related oxides. Universitetet i Oslo. Full text in Research Archive Show summary

  Hydrogen will play a key role in a zero-emission society, and proton (H+) conducting oxides have gained interest as solid-state electrolytes for next-generation electrochemical devices for fuel cells and electrolyzers. Understanding the effect of structure on materials functional properties is important for enhancing the performance of such electrolytes. Oxides with fluorite related crystal structures are interesting for their high oxide ion and proton (H+) conductivities, and in this work the relationship between the atomic structure and the materials properties such as ionic conductivity and hydration properties have been studied for three different oxides. They are oxygen deficient with respect to the fluorite structure and the vacant oxide ion sites can thus be ordered or disordered. Through a combination of different experimental and computational methods the nature and degree of ordering and the atomic structure have been determined, and correlated to the properties of the cations present, such as size and electronegativity. The work further focuses on whether ordering the oxide ion vacancies affects the hydration and consequently the proton conductivity. The results have led us to propose a new model for hydration of heavily doped yet disordered fluorite oxides.

• Johansen, Hege Westvold; Haugsrud, Reidar & Strandbakke, Ragnar (2020). Defects and transport in donor doped LaNbO4. Universitetet i Oslo. Full text in Research Archive
• Johansen, Hege Westvold & Haugsrud, Reidar (2020). Defects and transport in donor doped LaNbO4. Universitetet i Oslo. Full text in Research Archive
• Desissa, Temesgen D.; Norby, Truls Eivind & Haugsrud, Reidar (2018). Stability and properties of materials and interfaces for oxide thermoelectrics. Universistetet i Oslo. Full text in Research Archive
• Liu, Xin; Haugsrud, Reidar; Bjørheim, Tor Svendsen & Fjellvåg, Helmer (2018). Defect, Stability and Transport in Oxyhydrides. Universitetet i Oslo. Full text in Research Archive
• Stub, Sindre Østby; Haugsrud, Reidar & Norby, Truls Eivind (2017). Protonic Conduction in Porous Oxides. Universitetet i Oslo. Full text in Research Archive
• Løken, Andreas; Haugsrud, Reidar; Norby, Truls Eivind & Bjørheim, Tor Svendsen (2017). Hydration thermodynamics of oxides. Universitetet i Oslo. Full text in Research Archive
• Emhjellen, Linn Katinka; Haugsrud, Reidar; Bjørheim, Tor Svendsen & Strandbakke, Ragnar (2017). Defects and Transport in SrFe1-xMoxO3-δ. Universitetet i Oslo. Full text in Research Archive
• Gutterød, Emil Sebastian; Haugsrud, Reidar & Polfus, Jonathan M. (2016). An Experimental and Computational Study of Nitrogen Activation on Promoted Ruthenium Catalysts. Universitetet i Oslo. Full text in Research Archive
• Modestino, Rafael Albert Prato; Haugsrud, Reidar; Strandbakke, Ragnar & Vøllestad, Einar (2016). TRANSPORT PROPERTIES AND SURFACE KINETICS OF Ba0.8+xGd0.8La0.2+xCo2O6-d. Universitetet i Oslo. Full text in Research Archive Show summary

  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. The different basicity in the oxygen sites defined (O1, O2 and O3) is used to elucidate the hydration of the material. O3, the always-filled oxygen site is considered the main site for protonation due to its basicity (relative to the other oxygen sites). The adjacent vacancies in O2, a unique feature to BGLC, then allow for hydration. TGA hydration data resulted in an extracted entropy and enthalpy of hydration of ~ -120 J/molK and -46 kJ/mol respectively for all compositions of BGLC. Thourough agreement between the techniques used allow the characterization of the material properties, and the development of BGLC as future cathode material.

• Lervik, Adrian; Haugsrud, Reidar; Diplas, Spyridon & Gunnæs, Anette Eleonora (2016). Structural- and Compositional Investigations of Grain Boundaries in Y-Doped BaZrO3. Universitetet i Oslo. Full text in Research Archive Show summary

  Proton-conducting electrolytes are candidates for a range of electrochemical applications. The search for one which may operate in the intermediate temperature range of 400-800 °C has been ongoing for a while, and Yttrium-doped BaZrO3 (BZY) have been established as one of the most promising materials. Unfortunately, its highly refractory nature makes processing difficult, and generally results in a small grained polycrystalline material with high areas of highly resistive grain boundaries. The cause of resistive grain boundaries is attributed to the formation of space-charge layers, where negatively charged defects segregate close to the grain boundaries in order to compensate the positively charged grain boundary core. A sample prepared unconventionally using extreme temperatures of 2200 °C overcame the grain boundary problem, but an unanswered question is: what did occur during the high temperature treatment? In this thesis, conventional samples were prepared by the Solid State Reaction (SSR) method and characterised by a range of methods. X-Ray Diffraction (XRD) indicates the presence of two cubic phases with slightly different lattice parameters, and X-ray Photoelectron Spectorscopy (XPS) shows Y situated two different chemical states with a seperation of ~2.6 eV. Energy Dispersive Spectroscopy (EDS) performed in the Transmission Electron Microscope (TEM) shows an enrichment of Y and depletion of Ba at the grain boundaries. These are strong indications that Y also substitutes on Ba site in the structure. The microstructure has grains of ~600 nm and the grain boundaries mostly adapt random configurations. Conductivity measurements by impedance spectroscopy indicates the presence of highly resistive grain boundaries, as the conductivity of grain boundaries is three orders of magnitude lower than that of bulk (0.001 vs. 0.000001 S/cm at 400 °C in wet O2). In the high temperature sample the same degree of Ba depletion is not observed, but Y also segregates to the grain boundaries. The grain boundaries are also more frequently near a Coincident Site Lattice (CSL) type grain boundary; an indication of grain boundary migration during the high temperature treatment. Furthermore, two samples prepared through the Solid State Reactive Sintering (SSRS) method, with Ba non-stoichiometry (x = ±0.02, in Ba_{x}Y_{0.15}Zr_{0.75}O_{3}), have been studied by TEM. The goal was to gain more understanding on how the addition of small amounts of NiO assists in the sintering stage, and how it is distributed in the resulting sample. The results shows that Ni rich phase(s) are present at the grain boundaries and triple points in the Ba rich sample. In the Ba deficient sample no secondary phases are observed, but the Ni content is found to be twice as high at the grain boundaries than in the grain interior (bulk).

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