ESS Science Symposium - Neutrons for Future Energy Strategies

27 May 2013, 08:00 → 29 May 2013, 20:00 Europe/Zurich

Paul Scherrer Institut

Neutrons for Future Energy Strategies

May 27 - 29, 2013 at Paul Scherrer Institute Villigen, Switzerland

Monday, 27 May

Registration

Opening

1 Opening - K.N.Clausen

Speaker: Dr Kurt N. Clausen (PSI)

Session I

2 Energy Research at the Paul Scherrer Institute

Energy is the topic of two of PSI's research departments. Harvesting of renewable energies, transformation to energy carriers for flexible use, and efficient conversion of final energy into energy services have remained at the focus of General Energy. As a first energy chain, biomass resources that are not competing with higher value-added use, are transformed into methane, which can then be converted efficiently to electricity, heat, and motive power in near-zero emission combustion devices. The second value chain targets harvesting solar energy, which is transformed into either electricity or hydrogen produced by high-temperature solar chemistry. The envisaged area of application is transportation, based on either electrochemical storage in advanced batteries or on fuel cell propulsion trains. Advanced characterization at PSI's large facilities is intensely used in the experimental activities. These efforts are framed by experimental studies of environmental consequences of the energy-related activities for the atmosphere, by life cycle analysis, and by studying scenarios for the future development of the energy system.

Speaker: Alexander Wokaun (Paul Scherrer Institut)

3 Solar Fuels : from natural to artificial photosynthesis - chemistry for the production of hydrogen from solar energy and water

The paper will discuss the need for Solar Fuels and overview the different scientific paths to achieve this goal. Visions and strategies in research in the Swedish Consortium for Artificial Photosynthesis and the European network SOLAR-H2 will be covered. Our research aims for the production of hydrogen from solar energy and water. Water shall be oxidized in a catalytic process using solar energy. The electrons from water shall be used in a second process to reduce protons to hydrogen. We apply a biomimetic approach where we copy key principles from natural enzymes that accomplish partial reactions. Water oxidation using solar energy is carried out by Photosystem II using a catalytic Mn4 complex. In our chemistry we also develop Mn-based catalytic systems and use a photoactive Ru-center to drive oxidative electron transfer. I will describe our recent research on light driven, multi-electron transfer in these Mn systems and a recent water oxidizing catalyst based on a cobalt nano-particle. To accomplish reduction of protons to hydrogen we mimic the di-iron center in hydrogenase enzymes. Some recent results on these biomimetic Fe-Fe complexes will be described. Magnuson, A., Anderlund, M., Johansson, O., Lindblad, P., Lomoth, R., Polivka, T., Ott, S., Stensjö, K., Styring, S., Sundström, V. and Hammarström L. (2009) Biomimetic and Microbial Approaches to Solar Fuel Generation. Accounts Chemical Res., 42, 1899-1909 Ott, S., Styring, S., Hammarström, L., and Johansson, O. (2010) Towards Solar Fuels using a biomimetic Approach. Progress in the Swedish Consortium for Artificial Photosynthesis. In “Energy production and storage”; Inorganic Chemical Strategies for a Warming World, edited by Robert Crabtree, Chichester, UK: John Wiley & Sons, Ltd, pp 199-227 Shevchenko, D., Anderlund, M. F., Thapper, A. and Styring, S. (2011) Photo-driven water oxidation with visible light using a cobalt containing catalyst Energy and Environmental Science, 4, 1284-1287 Risch, M., Shevchenko, D., Anderlund, M.F., Styring, S., Heidkamp, J., Lange, K.M., Thapper, A. and Zaharieva, I. (2012) Atomic structure of cobalt-oxide nanoparticles active in light-driven catalysis of water oxidation Intl J.Hydr. Research, 37; 8878-8888 S. Kaur-Ghumaan, L. Schwartz, R. Lomoth, M. Stein, S. Ott Catalytic (2012) Hydrogen Evolution from Mononuclear Ferrous Carbonyl Complexes as Minimal Functional Models of the [FeFe] Hydrogenase Active Site Angew. Chem. Int. Ed. 49, 8033-8036.

Speaker: Prof. Stenbjörn Styring (Photochemistry and Molecular Science, Department for Chemistry – Ångström laboratory. The Ångström Laboratory, Uppsala University, Sweden)

10:30 Coffee Break I

Session II

4 Protein dynamics tunes energy levels for efficient light harvesting in photosynthesis

Photosynthetic antenna complexes can serve as role models for bioinspired artificial solar cells. Light harvesting and excitation energy transfer in photosynthesis is relatively well understood at cryogenic temperatures up to ~100 K (see e.g. [1] and references therein), where crystal structures of several photosynthetic complexes including the major antenna complex of green plants (LHC II) are available at nearly atomic resolution [2,3]. The situation is much more complex at higher or even physiological temperatures, because spectroscopic properties typically undergo drastic changes at about 120 – 150 K. Recently, we have addressed this problem using a combination of quasielastic neutron scattering (QENS) and optical spectroscopy on native LHC II and mutants lacking individual pigment molecules. Absorption difference spectra of mutant LHC II reveal spectroscopic changes at ~80 K for individual chromophores. The complementary QENS data indicate an onset of conformational protein motions at about the same temperature. This finding suggests that excited state positions in LHC II are affected by protein dynamics. In more detail, this would mean that at cryogenic temperatures the antenna system is trapped in a certain protein conformation. At higher temperature, however, a variety of conformational substates with different spectral position may be thermally accessible. This finding implies that pigment-protein interactions „fine-tune“ electronic energy-levels of LHC II for efficient excitation energy transfer to the reaction center at physiological temperatures. 1. Jankowiak, R.; Reppert, M.; Zazubovich, V.; Pieper, J.; Reinot, T. Chemical Reviews (2011), 111 (8), 4546. 2. Liu, Z. et al., Nature 2004, 428, 287. 3. Standfuss, J.; Lamborghini, M.; Kühlbrandt, W.; van Scheltinga, A.C.T. EMBO J. 2005, 24, 919. 4. Pieper, J.; Schödel, R.; Irrgang, K.-D.; Voigt, J.; Renger, G. J. Phys. Chem. B. 2001, 105, 7115. 5. Rogl, H.; Schödel, R.; Lokstein, H.; Kühlbrandt W.; Schubert, A. Biochemistry 2002, 41, 2281. 6. Pieper, J.; Rätsep, M.; Jankowiak, R.; Irrgang, K.-D.; Voigt, J.; Renger, G.; Small, G. J. J. Phys. Chem. A. 1999, 103, 2412.

Speaker: Prof. Jörg Pieper (University of Tartu)

5 The investigation of materials related to nuclear technologies by means of neutron imaging methods

In the context of nuclear installations like nuclear power plants as well as accelerators and target facilities, there are many research topics relating to safe operation, improved utilization of nuclear fuel, waste disposal and final disassembling. In particular, non-invasive and non-destructive methods are needed to gain insight into non- or difficult reachable locations in materials or components, to reduce the risk of contamination and the applied doses for the involved scientists. Neutron imaging can provide very interesting options for the study of nuclear fuel and its cladding. The high penetration power for heavy elements (in particular uranium) and the high contrast for light elements (hydrogen, boron) provide often better condition than the more common X-ray techniques. It makes it possible to apply special sample environments like shielding or furnaces with well defined atmospheres and use them for in-situ experiments. On the one hand, it becomes possible to investigate the integrity of spent fuel even if the high burn up is accompanied with the emission of large amounts of gamma radiation. In respect to the cladding, the uptake of hydrogen by the Zr alloy is linked to the risk for embrittlement and failure. Studies with irradiated cladding were successfully done. Current investigations are focused onto the understanding of the hydrogen ingress to cladding under operational and accidental conditions where inactive samples are investigated ex-situ and under in-situ conditions. Additionally, basic research for instance of the hydrogen diffusion in zirconium or of the sequence of formation of chemical compounds during air oxidation of zirconium alloys is in progress. For the efficient use of nuclear fuel and the safe operation of power plants the thermal hydraulic conditions of the coolant flow are essential. Due to the high attenuation properties of neutrons for water, annular two-phase flows can be very efficiently studied on-line and in 3D in dummy fuel rod bundles. We also used the technology of neutron imaging of highly activated samples for the study of target components of the SINQ target after 2 years of full exposure. The lead rods are sufficiently transparent for thermal neutrons and the request was to find out which “visible” modifications happen during proton beam exposure. The NEUTRA beam line is well equipped for such kinds of studies and can be used for similar experiments on request.

Speaker: Dr Stephane Valance (PSI)

6 Neutron diffraction supporting mechanical metallurgy

Reducing weight or increase operating temperature are possible ways to reduce energy consumption. For metals this usually means developing stronger microstructures so that less material has to be used or creep resistant alloys that can operate longer and at a higher temperature. The playground to optimize the mechanical properties is vast and that is why even after a long-standing mature research history in metallurgy, new microstructures with advanced properties are continuously emerging. The structure-mechanics relation in metals is truly multiscale: the atomic to the macro scale are connected by a series of reactions that determine the resulting microstructural evolution under load. The ability to use physics-based computational models at all lengthscales for the understanding and the prediction of the mechanical behavior has revolutionized engineering and contributed to new innovations. Neutron diffraction has contributed to a great extend to the science and engineering of metals. A neutron powder diffraction pattern is a static footprint of a microstructure providing information on all constituent phases. When performed insitu this footprint can be followed during deformation and give information on phase transformation mechanisms, degradation phenomena in fatigue and creep processes, or the dynamics of the development of microstresses in a Bauschinger tests. In recent years in-situ neutron diffraction has proven to be a very useful tool to validate and further develop computational models. This will be illustrated using examples of neutron diffraction studies performed at the time-of-flight strain scanner POLDI at SINQ which is equipped with an insitu tensile rig and soon also a biaxial tension/torsion deformation rig. The examples include research on superalloys, MAX phases, Al alloys and high-temperature bainitic steels.

Speaker: Dr Steven Van Petegem (PSI)

12:50 Lunch Break

Session III

7 THE CATALYTIC CARBON DIOXIDE – FORMIC ACID CYCLE FOR HYDROGEN STORAGE AND DELIVERY

The interconversion of hydrogen and carbon dioxide/carbonates to chemical energy carriers has attracted considerable interest for the development of novel energy technologies, because it combines hydrogen storage and CO2 utilization. Carbon dioxide and carbonates have been proven to be viable H2 vectors, as these widely available natural C1 sources can be easily hydrogenated to formic acid and formates. On the other hand, formic acid can be selectively decomposed into CO free carbon dioxide and hydrogen, H2 gas can be generated very efficiently from formic acid in homogeneous catalytic reactions, using ruthenium and iron catalysts with phosphine ligands.

Speaker: Prof. Gabor Laurenczy (EPFL)

8 Watching the formation of metal hydrides in situ

In the quest for low-cost, low-weight, high-capacity reversible hydrogen storage media, real-time in situ studies are gaining more attention recently. This is because it is now commonly accepted that the lack of reversibility is one of the key obstacles for the use of low-weight hydrogen stores. In order to follow the formation of crystalline solids both during the hydrogenation and the dehydrogenation process and including the hydrogen positions, in situ neutron powder diffraction is a powerful method. We have constructed a gas pressure cell for in situ neutron powder diffraction of solid-gas reactions such as hydrogenation (deuteration). The sample holder is based on a 10 cm long free standing sapphire crystal tube [1]. By proper orientation of the single crystal Bragg peaks of the container material can be avoided, resulting in a very clean background as compared to most other designs for gas-pressure cells made e. g. of silica or metals. Using a laser heating and gas pressure controller, the hydrogenation (deuteration) of intermetallics can be studied in real time routinely up to 100 bar gas pressure and 700 K at present. At a time resolution in the order of one minute high quality diffraction data can be collected suitable for detailed Rietveld analysis in most cases. This development allowed getting a deeper insight into reaction pathways of the hydrogen uptake in intermetallics and the formation of metal hydrides. In palladium the α→β transition of the hydride (deuteride) could be followed, yielding in a detailed picture of the H(D) distribution during the whole process. The hydrogenation of palladium rich intermetallics MPd3 (M = Mg, In, Tl) proceeds through metastable intermediates, which could be fully structurally characterized [2]. Moreover, a complete reaction mechanism was proposed, which allowed the planned syntheses of designed metastable intermetallic compounds and metal hydrides [2]. Further examples include the hydrogenation of Dy5Pd2, Zintl phases like SrGa2 and the light-weight hydrogen storage material Li3N, illustrating the potential and limitations of the sapphire single crystal based gas pressure cell for in situ neutron powder diffraction on solid-gas reactions. [1] B. C. Chakoumakos, C. J. Rawn, A. J. Rondinone, L. A. Stern, S. Circone, S. H. Kirby, Y. Ishii, C. Y. Jones, B. H. Toby, Can. J. Phys. 2003, 81, 183-189. [2] H. Kohlmann, N. Kurtzemann, R. Weihrich, T. Hansen, Z. Anorg. Allg. Chem. 2009, 635, 2399-2405. [3] H. Kohlmann, E. Talik, T. C. Hansen, J. Solid State Chem. 2012, 187, 244-248

Speaker: Prof. Holger Kohlmann (Leipzig University)

9 Phases of electrolytes controlled the degradation behavior in electrolyte-supported solid oxide fuel cell

Metal oxide membranes for solid electrolytes are critical components in high temperature electrochemical energy converters such as ceramic fuel cells and electrolyzers, and thus of high relevance for a sustainable energy economy. However we found that the major degradation of conductivity in the electrolyte-supported fuel cell stacks is caused from decay of ions conductivity contribution. Results from impendence spectra show that the part of ion conduc-tivity through the grain decreases and almost keeps the same values in the contribution through grain boundary. In this work, we applied the X-ray and Neutron powder diffraction on long term operated electrolyte material, 12 moles% Scandia doped stabilized zirconia (6ScSZ) from the real commercial electrolyte-supported fuel cell stacks. In the ScSZ phase equipment diagram, the Scandia elements doping stabilized zirconia shows the major phases in the structure would be separating into tetragonal T’ and cubic T’’ phases. The phase transition between 2 phase groups in the SZ is not controlled by diffusion process but rather with oxygen vacancies slightly displaced and ordered in the unit cell and transforms from cubic to tetragonal P42/NMC symmetry. In our quantitative phase analysis, the results also supported the phase composition changed with different aged time. After 1250 hours aged, the amount of tetragonal phase grows. Furthermore, in our observation, the transport properties can be healed after annealing above 1300 degree and the phase composition returned to one as pristine 6ScSZ.

Speaker: Dr Tzu-Wen Huang Huang (EMPA)

10 Dedicated Sample Environment for Energy Research

For a successful operation of a neutron facility it is of particular importance to provide the users the best technical and scientific support in order to perform highest impact investigations. The quality of the available sample environment support is certainly a key aspect for excellent scientific results. Except for the unique compatibility with complex sample environments, Neutron scattering offers several key advantages including sensitivity to oxygen and hydrogen, seen likely as the energy carrier in future energy distribution, which motivate research on hydrogen storage materials, hydride batteries and solid oxide fuel cells. The performance of the material components for these applications is sensitive to external parameters, such as the temperature and the partial pressure of Hydrogen, Oxygen or water. To achieve greater understanding it is essential to use complex sample cells for extensive in-situ studies under conditions that mimic the operational conditions for the real application. Sample environment at the Helmholtz-Centre Berlin is traditionally focused on extreme physical parameters combined with a strong user support. In the last decade the increasing complexity of neutron investigations required the development of different in-situ sample environment equipment. In this presentation we show several examples for neutron investigations using dedicated equipment for neutron scattering experiments under controlled gas atmospheres. Thereby, the focus is on structural investigations on host materials for gas storage [1-3] as well as on the in-situ synthesis and catalysis studies [4-7]. Examples of gas pressures cells, high and low temperature environments and gas dosing equipment are presented and discussed in the context of these and related applications. Another important issue is the support in sample- and experiment preparation by providing labs, expertise and equipment to the neutron users even beyond their particular beamline investigations. [1] Methane storage mechanism in the Metal-Organic Framework Cu3(btc)2: An in situ neutron diffraction study, J. Getzschmann, I. Senkovska, D. Wallacher, M. Tovar, D. Fairen-Jimenez, T. Düren, J. M. van Baten, R. Krishna, S. Kaskel, Microporous & Mesoporous Materials 136, 50 (2010) [2] Improving the Hydrogen Adsorption Properties of a Hydroxyl-Modified MIL-53(Al) Structural Analogue by Li-Doping, D. Himsel, D. Wallacher, M. Hartmann, Angewandte Chemie – International Edition 48, 4639 (2009) [3] CO2 Adsorption to Sub-Single Hydration Layer Montmorillonite Clay Studied by Excess Sorption and Neutron Diffraction, G. Rother, E.S. Ilton, D. Wallacher, T. Hauß, H.T. Schaef, O. Qafoku, K.M. Rosso, A.R. Felmy, E.G. Krukowski, A. Stack, R.J. Bodnar, Environmental Science & Technology 47, 205 (2013) [4] Hydrogen storage: the remaining scientific and technological challenges, M. Felderhoff, C. Weidenthaler, R. von Helmolt, and U. Eberle, Phys. Chem. Chem. Phys. 9, 2643 (2007) [5] Hydrogen cycling behavior of LiBD4/Al studied by in situ neutron diffraction, A. Remhof, O. Friedrichs, F. Buchter, P. Mauron, J.W. Kim, K.H. Oh, A. Buchsteiner, D. Wallacher, A. Züttel, J. Alloys and Compounds 484, 654 (2009) [6] In situ Neutron Diffraction Study of a Methanol Synthesis Catalyst under Working Conditions, T. Kandemir, D. Wallacher, M. Tovar, M. Behrens, Z. Anorg. Allg. Chem. 636, 2088 (2010) [7] In situ Neutron Diffraction as a Probe on Formation and Decomposition of Nitrides and Hydrides: A Case Study M. Widenmeyer, R. Niewa, T. C. Hansen, H. Kohlmann, Z. Anorg. Allg. Chem. 2013, 639, 285-295

Speaker: Dr Dirk Wallacher (Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner Platz 1, D-14109 Berlin, Germany)

17:00 Coffee Break II

Session IV

11 Materials Science for Future Energy Applications

One of the most important scientific problems to solve for our modern society is how to convert and store clean energy. In order to accomplish a paradigm shift in this field we need to understand the fundamental dynamical processes that govern the transfer of energy on an atomic scale. For future energy devices like solid-state batteries (SSB) as well as solid-oxide fuel cells (SOFC) this means understanding and controlling the complex mechanisms of ion diffusion in solid matter. Only recently, developments of state-of-the-art large scale experimental facilities e.g. neutron/muon spallation sources as well as free electron lasers, have opened new possibilities for studying such intrinsic material properties in a straightforward manner. Layered transition metal oxides (TMOs) have been extensively studied both for their correlated electronic properties (frustrated magnetism and superconductivity) as well as for energy applications e.g. Li-ion batteries or thermoelectrics. Recently these two fields have been unified under the framework of the layered NaxCoO2 family where Na-ion vacancy order as well as dynamics has been shown to tailor low-temperature magnetic and thermoelectric properties. In addition, room-temperature sodium batteries are currently receiving considerable attention since the available lithium reserves of our planet are very limited. In many ways the NaxCoO2 compound is the Na-analog of the most common Li-ion battery electrode LixCoO2. Hence, understanding Na-ion diffusion mechanisms of NaxCoO2 would seem a logical first step. Consequently, we have conducted systematic studies of this compound using neutron powder diffraction (NPD), quasi-elastic neutron scattering (QENS) and muon spin relaxation/rotation ($\mu$SR) as a function of temperature as well as Na-content (x) and pressure. Our high-resolution T-dependent NPD data display a "melting" of the ordered Na-ion planes in two steps, involving an intriguing crossover from 1D to 2D Na diffusion [1]. It is evident that the onset and evolution of ion-diffusion is intrinsically linked to a series of subtle structural transitions that unlocks the diffusion pathways. The diffraction data is readily supported by our preliminary QENS experiments [2] that show a strong increase of inelastic intensity at two different temperatures, indicating the activation of two unique diffusion mechanisms. Further, from our recently developed $\mu$SR techniques [3] it is possible to follow the Na-ion hopping-rate ($\nu$) on a local scale. $\nu$(T) is found to increase exponentially around room-temperature, in line with the onset of “melting” in the NPD/QENS data. The temperature dependence is well fitted by an Arrhenius type equation, indicative of a diffusive process and the activation energy as well as diffusion constant (DNa) can be extracted. Additional $\mu$SR measurements as a function of Na-content (x) [4] display an interesting, yet counterintuitive increase of Na-diffusion with decreasing c-axis length (increasing x). Such behavior motivated us to perform also pressure dependent NPD measurements, which indicated the same type of increase in Na-dynamics with elevated pressure (i.e. smaller c-axis) [5]. In summary, our current research has established a novel and detailed insight into the ion diffusion mechanisms in this group of compounds. This allows us to contemplate and actively consider future possibilities for tuning fundamental physical properties as well as solid state engineering of energy related materials with improved functional properties. REFERENCES [1] M. Medarde, M. Månsson et al., arXiv:1302.0708 [2] F. Juranyi et al., publication in progress [3] J. Sugiyama, M. Månsson et al., PRL., 103, 147601 (2009) [4] M. Månsson et al., Submitted for publication [5] Y. Sassa, M. Månsson et al., publication in progress

Speaker: Dr Martin Mansson (Laboratory for Quantum Magnetism (LQM), EPF Lausanne)

12 Bottom-up approach to high performance magnets

Permanent magnets are responsible for the inter-conversion between energy in the form of electricity and motion. Therefore development of improved permanent magnets is paramount for a sustainable future. In recent years the world market for high performance permanent magnets has been dominated by neodymium rare-earth magnets, but unfortunately rare-earth minerals are found only in few geographical areas. This is causing geopolitical and strategic issue and magnetic materials without rare-earth elements are urgently needed. Therefore we are working on designing and producing improved permanent magnetic materials that do not include rare-earth elements. A good candidate for permanent magnetic applications is SrFe12O19 a ferrimagnetic compound with high coercivity field and a hexagonal symmetry. Supercritical synthesis of SrFe12O19 allows size and shape control of nanoparticles to produce single domain nanoparticles. The produced powders have been characterized by Rietveld analysis refinement of X-ray powder diffraction data. Neutron powder diffraction data is underway to characterize the atomic spin configuration and the effect of particle size.

Speaker: Dr Mogens Christensen (Aarhus University)

Tuesday, 28 May

Session V

13 Using neutron and synchrotron sources for in industrial catalysis

The importance of large-scale facilities such as neutron and synchrotron sources in industrial catalysis still increases. Developments of new neutron- and synchrotron-based techniques both contribute to and are driven by developments in catalysis. The need to study catalysts at high temperatures and pressures in a reactive gas or liquid atmosphere resulted in the design and construction of in situ and operando reactors to perform structural characterization of catalysts under relevant reaction conditions. Neutron- and synchrotron-based techniques are especially versatile for the study of catalysts under reaction conditions due to the high penetrating power of neutrons and X-rays, the tunability of the energies over a broad range and the possibility to collect data with a high temporal and spatial extent. Several relevant properties such as elemental composition, chemical state, bond distances, particle sizes and size distributions, phase composition and the structure of the pore system can be studied by synchrotron-based methods. Similar and complementary information can be obtained by neutron-based techniques. The development of single techniques such as XAFS to analogues with a high time resolution (QEXAFS) was broadened over the years to the combined use of several techniques, as no single technique can give all information necessary to understand the catalyst structure. Combinations of several in situ synchrotron-based techniques, e.g. XAFS/(A)XRD and SAXS/WAXS as well as the combination of synchrotron techniques with laboratory-based techniques such as XAFS/Raman and XAFS/IR-spectroscopy, were developed. Also, the range of length scales has broadened over the years and with the advent of 3rd generation synchrotron sources, with highly brilliant beamlines, new options for studying catalysts and related nano-materials with a high spatial and temporal resolution were enabled. X-ray microscopy and X-ray tomography can be used to study the pore system of a catalyst and crack formation in catalyst tablets on many different length scales. Pore characterization is of crucial importance for heterogeneous catalysts, because the reactants and products have to be able to enter and exit the catalytic active sites present within the pores. In this contribution some examples are given of the industrial use of some neutron- and synchrotron-based techniques for the understanding and development of heterogeneous catalysts. The use of in situ XAFS, AXRD and complementary neutron diffraction and SAXS for the characterization of Cu-based methanol-synthesis catalysts will be shown. Furthermore, the use of micro-tomography in industrial catalysis for the investigation of the pore system of DeNOx catalysts for removal of NOx from exhaust gasses and the study of cracks in catalyst tablets will be illustrated. Finally, some challenges for the collaboration between large-scale facilities and industrial users will be highlighted.

Speaker: Dr Alfons Molenbroek (Haldor Topsøe A/S)

14 Status Report of the J-PARC MLF (The J-PARC Materials & Life Science Experimental Facility)Status Report of the J-PARC MLF (The J-PARC Materials & Life Science Experimental Facility)

J-PARC MLF was designed to be a 1 MW spallation neutron source. Presently the power of the proton accelerator is 300 kW with a very stable operation at 94%, a world-class stability, after recovering in January 2012 from the damages by the devastating disaster happened in March 2011. In order to increase the proton power over 300KW, we need an improvement on the target to mitigate the pitting on the Hg-target container. Now we have been injecting helium micro bubbles in the target. The Laser Doppler vibrometory from the container showed us that vibration on the proton bombardment has obviously reduced by the injection. 20 instruments have been already funded. 16 of them are operated for user program and four instruments are under either commissioning or construction. Operational time for user program in JFY2012 was about 180 days, and we have received more than 550 experimental proposals from users. We have introduced innovative instrument design, such as multi-Ei measurement, pulse-shaping chopper at beam ports viewing the coupled moderator, intensive background suppression design, event-recording data acquisition etc. Instruments perform quite well at world class and users are very much enjoying experiments. World-class scientific outputs have been already created in various scientific fields, ranging from Li-battery science to bio-molecular science. Since J-PARC is internationally open for users, we have got experimental proposals from abroad more than 10% of the whole proposals. More than 30% of proposals have come from industries, such as Toyota, Nissan, Honda, Panasonic and other big industries. This fact has revealed a new horizon has come in the neutron scattering science in the 21 century. We are expecting the number of proposals and users will be improved more than three times at 1MW in three years’ time.

Speaker: Dr Masatoshi Arai (J-PARC Center JAEA)

15 Neutron imaging and advanced electrochemical analysis of operating fuel cells

Polymer electrolyte fuel cells (PEFCs) are expected to play an important role in the future energy landscape, as the used fuel (hydrogen) allows a better integration of renewable sources. Although they can be considered a technologically viable product for mobility applications (automobiles, buses), the deployment of PEFCs still requires a reduction of the cost of this technology. In combination with the reduction of material costs (e.g. lower platinum loadings), an optimization of the transport processes results in an increased power per unit of area, resulting in a lower cost for a specified power output. In this optic, the issues related to water management in PEFCs have been extensively studied in the past decade. Neutron imaging is particularly well suited for water visualization, because of the high contrast of liquid water and the good transparency of fuel cell construction materials. Although the spatial resolution of neutron imaging is limited, recent improvement in the imaging setups [1] combined with specific anisotropic enhancements for fuel cells [2] allowed meeting the resolution required for resolving the different layers of a cell. In this talk, a short overview of the uses of neutron imaging in fuel cell research (at PSI and other institutes) will be given. Detailed results will be presented for the latest research results obtained at PSI using the newly developed multi-cell setup [3], which allows operating and imaging of up to 6 small scale cells. These results are not limited to water visualization, but combine imaging with advanced electrochemical analysis methods such as Electrochemical Impedance Spectroscopy (EIS) and Pulsed Gas Analysis (PGA) [4, 5]. Finally, an outlook will be given about the possible future uses of neutron imaging in electrochemical energy research. 1. E. Lehmann, G. Frei, G. Kühne, and P. Boillat, Nucl. Instr. Meth. A 576, 389 (2007). 2. P. Boillat, G. Frei, E. H. Lehmann, G. G. Scherer, and A. Wokaun, Electrochem. Solid St. 13, B25 (2010). 3. P. Oberholzer, P. Boillat, R. Siegrist, A. Kaestner, E. H. Lehmann, G. G. Scherer, and A. Wokaun, Electrochem. Commun. 20, 67 (2012). 4. P. Oberholzer, P. Boillat, A. Kaestner, E. H. Lehmann, G. Scherer, T. J. Schmidt, and A. Wokaun, J. Electrochem. Soc., Submitted for publication (2013). 5. P. Boillat, P. Oberholzer, A. Kaestner, R. Siegrist, E. H. Lehmann, G. G. Scherer, and A. Wokaun, J. Electrochem. Soc. 159, F210 (2012).

Speaker: Dr Pierre Boillat (Paul Scherrer Institut)

11:00 Coffee Break III

Session VI

16 Improving Performance and Efficiency of an Existing Energy Solution

While there is a strong initiative to develop new (ideally renewable) energy sources for future applications, there is still a requirement for sustaining existing energy solutions, but with improved performance and efficiency. In the foreseeable future, there will continue to be a need for efficient steam based turbo-machinery for power generation, but with greater operating flexibility, to enable faster start-up times when required to supplement unavailable renewable resources such as wind or solar energy (e.g. the wind does not always blow and the sun does not always shine). Turbine start-up times can be unnecessarily slow, simply because the constitutive model equations used to represent the cyclic response of materials used for high temperature rotors can be overly conservative. The objective of a recently completed Swiss CCMX-MERU funded project was to develop an elevated temperature evolutionary cyclic plasticity model with microstructural quantities providing the internal state variables to enable turbine start-up times to be determined in a less conservative way. Details of the gained experience of using neutron diffraction facilities in Europe and the United States for making ex-situ measurements to determine dislocation density and sub-grain size evolution during low cycle fatigue loading of a high temperature turbine rotor steel at elevated temperatures are presented, along with complementary microstructural evidence obtained by electron microscopy. The way in which this microstructural information was used to underpin a new microstructurally based evolutionary cyclic plasticity model is also reviewed. Turbo-machinery efficiency is improved by increasing the temperature of the steam at the inlet stage of the high pressure module and/or by increasing the dimensions of the last stage blades at the exhaust of the low pressure module. As last stage blade size is increased, upper blade aerofoil speeds increase and enhanced water droplet erosion becomes a problem. One solution to limit this form of damage is to locally thermal harden blade leading edges. Unfortunately, limiting the risk of erosion damage in this way, increases local susceptibility to environmental cracking. Susceptibility to environmental cracking depends on material (hardness), environment and applied stress, and local applied stresses can be minimized by laser peening to generate compressive surface residual stresses to depths of ~1-2mm. While the effectiveness of this solution can be demonstrated by a hole drilling technique on test plates, proof of concept on complex blade geometries requires residual stress measurement by neutron diffraction.

Speaker: Dr Stuart Holdsworth (EMPA)

17 Neutron scattering studies of structure and dynamics of proton conducting perovskites for next-generation fuel cells

Understanding the fundamental properties of materials of relevance for alternative energy technologies is crucial in addressing the global challenge of cleaner sources of energy. In this presentation I aim to demonstrate the important role that neutron scattering now plays in advancing the state of the art of the fundamental understanding of proton conducting oxides, which show potential to be used as electrolytic membranes in next-generation, environmentally friendly, fuel cells, operating in the intermediate temperature range from ~200 to ~500 °C [1]. In particular, the breadth of recent neutron scattering work on perovskite type oxides, which continue to be considered as the most promising materials for intermediate temperature applications [2], is reviewed. Key fundamental properties that are addressed include crystal structures and proton sites, hydrogen-bonding interactions, and proton dynamics. Techniques, which are touched upon, are neutron diffraction, neutron total scattering, and in- and quasi-elastic neutron scattering. Furthermore, the perspectives for future neutron studies within this field of research [3] are discussed. [1] L. Malavasi, C. Fisher, S.M. Islam, Chem. Soc. Rev. 39 (2010) 4370. [2] E. Fabbri, L. Bi, D. Pergolesi, E. Traversa, Adv. Mater. 24 (2012) 195. [3] M. Karlsson, Dalton Trans. 42 (2013) 317.

Speaker: Dr Maths Karlsson (Chalmers University of Technology)

18 Nanostructure of the aqueous phase and impact on proton transport in radiation-grafted fuel cell membranes

We present a SANS study of radiation-grafted fuel cell membranes containing styrenesulfonic acid. The influence of the nano-structure of the aqueous phase on the proton conductivity is studied. We model the structure of the aqueous phase using a stochastic approach and estimate the tortuosity of the aqueous phase via the self-diffusion of a Brownian walker. We find a strong dependence of the tortuosity on the volume fraction of the aqueous phase. The long-range proton diffusion clearly correlates with tortuosity and is found to govern the proton conductivity.

Speakers: Dr Sandor Balog (Adolphe Merkle Institute, University of Fribourg), Dr Urs Gasser (PSI / LNS)

13:20 Lunch

19 PSI tour

16:30 Coffee break IV

Session VII

20 Molecular Spectroscopy, Computer Modelling and the State of the Art in INS spectroscopy for Energy Materials

Molecular spectroscopy is a very powerful tool to study the dynamical properties of solid, liquid and gases. Inelastic Neutron scattering (INS) is a very powerful tool to study hydrogen-containing materials. With the development of neutron spallation sources, and the use of epithermal neutrons, inelastic neutron scattering can measure the vibrational spectra of materials on the whole range of vibrational motions (0-4400 cm−1) and effectively opening up the field of neutron spectroscopy [1]. The recently commissioned Lagrange instrument at the ILL, although based at a reactor source can also access up to similar energy transfers. With the new generation of neutron instruments, like the ones at the ESS it will be possible to expand the realm of INS spectroscopy to time resolved experiments and beyond hydrogen. These sources have increased neutron fluxes and are making possible to increase the number of spectroscopic neutron studies of gas adsorption, catalysis, energy materials etc. Computer modeling is crucial in understanding and interpreting vibrational spectroscopy, in particular the correlation between model and experiment is bridged by the aClimax program [2]. In this paper I will present the state of the art in neutron scattering spectroscopy showing applications to study in-situ ammoniation reactions, metal hydrides for hydrogen storage applications [3] as well as CO2 and SO2 gas sequestration at source using MOFs [4]. I will also discuss the use of computer modeling to aid the interpretation of results and future science that will be possible when the ESS comes on-line. References: [1] Mitchell PCH, Parker SF, Ramirez-Cuesta A, Tomkinson J. Vibrational Spectroscopy with Neutrons, with applications in Chemistry, Biology, Materials Science and Catalysis. London: World Scientific; 2005. [2] Ramirez-cuesta, A. Computer Physics Communications 2004, 157, 226–238. [3] Ramirez-Cuesta, A. J.; Jones, M. O.; David, W. I. F. Materials Today 2009, 12, 54–61. Borgschulte, A.; Gremaud, R.; Züttel, A.; Martelli, P.; Remhof, A.; Ramirez-Cuesta, A.; Refson, K.; Bardaji, E.; Lohstroh, W.; Fichtner, M.; Hagemann, H.; Ernst, M. Physical Review B 2011, 83, 024102. [4] Yang, S.; Sun, J.; Ramirez-Cuesta, A. J.; Callear, S. K.; David, W. I. F.; Anderson, D. P.; Newby, R.; Blake, A. J.; Parker, J. E.; Tang, C. C.; Schröder, M. Nature chemistry 2012, 4, 887–94.

Speaker: Dr Ramirez-Cuesta Timmy (ISIS STFC)

21 Proton dynamics in polymeric electrolyte membranes for high-temperature fuel cells: incoherent neutron scattering study

Polybezimidazole (PBI) membranes attract increasing interest as electrolytes for high-temperature polymer fuel cells with a typical operation temperature of 160°C. After being loaded with phosphoric acid PBI membranes provide very good proton conductivity which increases with an increasing amount of acid in the system. Additionally, such membranes show good chemical resistance and high glass transition temperature (~700 K). Although this kind of material has been already studied macroscopically (conductivity, rheology etc.), the microscopic dynamics has not been investigated in detail except from some molecular dynamic simulations. The neutron scattering techniques offer a new window to reveal the microscopic processes which are related to electrical ion conduction and allow to study the dynamics of protons and the polymer matrix separately. The Q-dependence of the scattering provides additional information about the system. Recent backscattering and neutron spin-echo (NSE) results will be presented.

Speaker: Dr Oxana Ivanova (Juelich Centre for Neutron Science, Outstation at FRM-II (MLZ), Forschungszentrum Juelich, Garching, Germany)

22 ESS – Instrumentation at the European neutron source of the future

The ESS is currently planning a next generation spallation neutron source to be built in Lund, Sweden. The 5MW source with a repetition rate of 14Hz is with a pulse duration of 2.86ms designed to be a long pulse source. The unique source parameters also trigger unique instrumentation solutions in order to take maximum advantage of the powerful source for all kinds of instruments. A straw-man suite of 22 instruments to be built at the ESS is currently under intense investigation and concepts enter the selction phase. Among those are several that are key to the science topic of this science symposium. The combination of the high source brilliance and unique instrument solutions is foreseen to push the boundaries of science that is currently feasible through the utilization of the unique probe, which neutrons represent for large number of applications. Envisaged efficiency gains up to more than an order of magnitude will allow for smaller samples, more irregular or sophisticated and hierarchical structures as well as faster kinetics or slower dynamics in systems to move into the focus of neutron scattering.

Speaker: Dr Markus Strobl (ESS-AB)

23 Closing Remarks / Discussion

Conference Dinner

Schloss Böttstein

Wednesday, 29 May

09:00 Departure