2020 Spring Meeting
Nanomaterials and advanced characterizationO
New developments in the modeling and analysis of radiation damage in materials II
Nowadays, it is common to find technological environments subject to irradiation with energetic particles, such as for instance materials in spintronics, semiconductors, space applications or nuclear reactors. This particle/matter interaction strongly affects the properties of the materials. This symposium will provide a forum to discuss the latest development in the characterization and modeling of particle/solid interactions.
The use of particle (ions, photons, neutrons, protons...) beams over a broad range of energies is a powerful tool to synthesize, test, and modify the properties of advanced materials. On the other hand, there also exist technological applications subject to undesired energetic particle fluxes that strongly degrade their performances. Research and applications of energetic particle beams encompass, among others, advanced electro-optical devices, nanostructures, strain engineering, nuclear materials, and space exploration. In most cases, particle beam modification of materials relies on the energy transfer from the energetic particles to atomic nuclei and/or electrons of the target. Usually, the deposited energy leads to defect generation and damage accumulation. These phenomena are sometimes desired, e.g., to simulate radiation environments such as those encountered in space and nuclear reactors; but they may also be a drawback, for instance in ion doping processes, or in the synthesis of nanostructures. In any case, understanding the mechanisms of damage formation and accumulation in materials as a result of energy deposition under irradiation is a crucial task to tackle.
This symposium is the follow-up of the 2018 edition which took place during the E-MRS Spring meeting and gathered ~ 60 scientists (speakers + posters) from more than 10 countries around the world. The aim of this symposium is therefore to provide a forum for researchers to present and discuss the developments and improvements of experimental characterization techniques, computational tools, theoretical models and codes for data fitting in the field of radiation damage. Special focus will be given to techniques, protocols, and methodologies allowing damage quantification. The coupling of experimental and computational characterizations will also receive particular attention. Finally, recent progress in in situ measurements, small-scale testing as well as improvements of conventional techniques to investigate radiation damage will also be addressed. To finish, this symposium is cross-disciplinary on a wide range of materials including metals, semiconductors, and iono-covalent materials with different dimensionality (e.g. 0D quantum dots, 1D nanowires or tubes, 2D thin film materials and 3D bulk materials) and on a broad range of irradiation conditions, experimental techniques and computational simulations.
Hot topics to be covered by the symposium:
The topics covered by the symposium include, but are not restricted to,
the following hot topics:
- Time resolved measurements of phase transformations, micro-structural changes, and surface effects
- High (time/space) resolution characterization of defects and disorder
- Computer simulation and modeling of damage formation and evolution
- Combination of computing and experimental approaches
- Quantification of radiation disorder
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Authors : Laurence Luneville, Philippe Garcia, David Simeone
Affiliations : CEA Saclay 91191 Gif sur Yvette, France; CEA Cadarrache, St Paul-lez Durance, France; CEA Saclay 91191 Gif sur Yvette, France
Resume : In non miscible AcB1-c binary alloys, radiation-induced mixing acts in conjunction with purely thermodynamic effects to produce steady states associated with unexpected micro-structures. In this work, we provide an analytical solution to the minimization problem of the pseudo free-energy which predicts the appearance of all possible steady states in the continuum approach. Two distinct types of steady states result from the minimization of this pseudo free energy: a non periodic one similar to the one observed at equilibrium, and a periodic one. For a given periodic steady state, it appears that different values of the average composition c will lead to different microstructures. This result, corroborated by previously reported and newly acquired experimental data, extends analyzing the emergence of non periodic steady states using a dynamic phase diagram to periodic steady states via a structure diagram which goes beyond the temperature concept.
Authors : Maik Lang, Eric O’Quinn, William Cureton, Alexandra Navrotsky, and Joerg Neuefeind
Affiliations : Maik Lang, Eric O’Quinn, and William Cureton: Department of Nuclear Engineering, University of Tennessee, Knoxville, TN, 37996, USA Alexandra Navrotsky: School of Molecular Sciences and Center for Materials of the Universe, Arizona State University, Temp AZ 85281 USA Joerg Neuefeind: Chemical and Engineering Materials Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN, USA
Resume : We present neutron total scattering with pair distribution function (PDF) analysis combined with high-temperature calorimetry as a new strategy for the characterization of radiation effects in materials. Irradiation experiments were performed at the UNILAC accelerator of the GSI Helmholtz Center with heavy ions of specific energy of 11.4 MeV/u. The use of swift heavy ions with a very high penetration depth (up to 100 µm) produces the sufficiently large irradiated sample mass (~150 mg) required for bulk structural and thermodynamic analysis. Structural characterization of the irradiated samples was performed at the Nanoscale Ordered Materials Diffractometer beamline at the Spallation Neutron Source (Oak Ridge National Laboratory). High temperature oxide melt solution calorimetry and differential scanning calorimetry was utilized to investigate the thermodynamic properties and energetic evolution using the same set of irradiated samples. We studied various ion-induced structural modifications, such as defect formation (CeO2 and ThO2), disordering (Er2Sn2O7), and amorphization (Dy2Ti2O7). This advanced analytical approach demonstrated that irradiation-induced structural modifications, and their thermal recovery, are much more complex than previously thought with distinct processes occurring over different length scales and temperature regimes. While radiation resistant simple oxides form low-energy defects that readily recover, amorphizable ternary oxides with a high degree of order form a local damage structure that persists structurally and energetically when subject to very high temperatures.
Authors : Jean-Paul Crocombette
Affiliations : DEN, Service de Recherches de Métallurgie Physique, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
Resume : The analysis of ion irradiation experiments often starts with an estimation of the number of defects (the so-called primary damage) created by the irradiation. Binary Collision Approximation (BCA) calculations provide such an estimation. In this framework, two types of damage calculation exist: Full Cascade and Quick Calculations. Full Cascade calculations describe fully the cascades while in Quick Calculations, only the trajectory of the ion is followed, and effective formulas give an estimation of the damage resulting from each collision of the ion. We will briefly recall our implementation of Quick Calculations of damage in the Iradina code , which is a modern, fast and open source alternative to SRIM. Quick calculations were implemented for elemental and multi-component solids. Good agreement is obtained with SRIM. We will show that Quick Calculations are unphysical in multi-component systems. First, the predicted numbers of created defects per atomic species are illogical. In addition, the balance between ballistic and electronic losses is not correctly reproduced. We therefore advise to favour Full Cascade over Quick Calculation because it more grounded physically and applicable to all materials. Quick Calculations remain a good option for pure solids in the case of actual quantitative comparisons with neutron irradiations simulations in which damage levels are estimated with the NRT (Norgett-Robinson and Torrens) formulas. : “Quick calculation of damage for ion irradiation: implementation in Iradina and comparisons to SRIM”, Jean-Paul Crocombette and Christian Van Wambekke, EPJ Nuclear Sci. Technol. 5, 7 (2019)
Poster session : Chairman to be defined
Authors : Alexandre Boulle, Vincent Mergnac
Affiliations : Institut de Recherche sur les Céramiques - CNRS UMR 7315 - Limoges France, Université de Limoges - Direction des Systèmes d’Information - Limoges France
Resume : The determination of sub-surface strain and disorder profiles is an essential step in the characterization of ion irradiated materials. Among the few existing techniques that allow to reach this goal X-ray diffraction (XRD) has the advantage of being simultaneously sensitive to strain and disorder, while being a non-destructive technique that allows to determine these quantities on an absolute scale. The main obstacle on this path is that the determination of the depth-resolved strain/disorder profiles requires a careful modeling and simulation of experimental data, a task that is often restricted to experts of the XRD technique. In order to make the XRD determination of strain/disorder profiles more intuitive we previously developed the free and open-source software RaDMaX (https://aboulle.github.io/RaDMaX/). RaDMaX is written in Python and therefore requires the installation of a full Python development environment which can be a disincentive for a non-negligible amount of potential users. With this in mind, we rewrote RaDMaX in order to make it able to run in a web browser. This program, RaDMax-online, allows the users to upload XRD data, analyze and fit the data on the web, and download the simulation results. It can be found at: https://aboulle.github.io/RaDMaX-online/ . The program entirely relies on free / open-source libraries related to the Python ecosystem (NumPy, SciPy, Jupyter, ipywidgets, bqplot, voila). The website is deployed using Docker containers.
Authors : B.L.Oksengendler*(1,2), A.F.Zatsepin(2), A.N.Kiryakov(2), N.N.Nikiforova(1), S.Suleymanov(3)
Affiliations : (1) Institute of Ion-Plasma and Laser Technologies (IPLT UAS), Tashkent, Uzbekistan; (2) Ural Federal University (UrFU), Yekaterinburg, Russia; (3) Materials Science Institute “Physics-Sun” (MSI UAS), Tashkent, Uzbekistan
Resume : A thorough analysis of the so-called hybrid objects made it possible to make a new classification of them and revealed a useful opportunity to distinguish them into the so-called complex systems. Their complexity can be described with very great commonality within the framework of five code concepts: nano, fractality, low dimensionality, chirality and synergetics. Applying the methods of radiation physics in series to each, and then in various combinations of the above features of hybrid media, it was possible to build models of basic atomic rearrangements such as radiation defect formation, radiation-stimulated diffusion, and basic radiation-stimulated quasi-chemical reactions. This allows you to outline a rough response of hybrid media to the effects of certain types of radiation, for example, fast electrons and ions, ordinary visible light and concentrated solar radiation. Particular attention is paid to electron-ion processes at interfaces with different curvatures. Cases of satisfactory agreement with experiment are discussed basing on various materials as examples.
Authors : 1Marie-Noëlle de Noirfontaine, 2Enric Garcia – Caurel, 3Sandrine Tusseau – Nenez, 1,4Mireille Courtial,1Olivier Cavani, 5Ferenc Borondics,1Frédéric Dunstetter, 1Dominique Gorse – Pomonti
Affiliations : 1Laboratoire des Solides Irradiés, Ecole Polytechnique, CNRS UMR 7642, CEA-DSM-IRAMIS, IP Paris, F-91128 Palaiseau Cedex, France 2Laboratoire de Physique des Interfaces et des Couches Minces, UMR CNRS 7647, Ecole Polytechnique, IP Paris, F-91128 Palaiseau Cedex, France 3 Laboratoire de Physique de la Matière Condensée, UMR CNRS 7643, Ecole Polytechnique, IP Paris, F-91128, Palaiseau Cedex 4 Université d’Artois, 1230 Rue de l’Université, F-62408 Béthune, France 5 Synchrotron SOLEIL, F-91192, Gif - sur - Yvette Cedex, France
Resume : Portlandite Ca(OH)2 and brucite Mg(OH)2 are isomorphous. They belong to the family of CdI2 type compounds with a layered structure giving them interesting physico-chemical and electronic properties for a number of industrial applications. Commercial powders were electron-irradiated at 2.5 MeV, room temperature and high dose rate (of order 20kGy/s) using the accelerator NEC Pelletron of the SIRIUS platform. Portlandite and brucite are found stable up to doses as high as 10 GGy and even more. Some subtle differences exist between these two compounds, that were revealed and analyzed by X-ray diffraction and IR spectroscopy.
Authors : N. Daghbouja*, M . Callistib*, H. S. Sena*, , M. Karlikc,d, J. Čapeke, P. Minárikd T. Polcara, V. Havránekf
Affiliations : a Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Technická 2, 160 00 Prague 6, Czechia b Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, United Kingdom c Department of Materials, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Trojanova 13, 120 00 Prague 2, Czechia d Department of Physics of Materials, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Prague 2, Czechia e Department of Solid State Engineering, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Trojanova 13, 120 00 Prague 2, Czechia f Nuclear Physics Institute CAS, v.v.i., Husinec - Řež 130, 250 68 Řež, Czech Republic
Resume : Sputter-deposited Zr/Nb nanoscale metallic multilayers (NMMs) with thin and thick periodicities were subjected to Cu+ irradiation with low and high fluences. Radiation-induced strain normally to interfaces was measured; the thinner layered exhibited a tensile strain in Nb layers, while a compressive strain applied in Zr layers. The thicker multilayer exhibited a compressive strain in both layers. The obtained results well supported by DFT calculations, which show that Cu trap at different positions depending on layer periodicities. For thin layers, Cu occupies tetrahedral site and basal plane of Nb and Zr respectively. For thick layers, Cu tends to form clusters.
Authors : D. Messou*(1, 2), S Béchu (2,1), S. Gaiaschi (3), M. Frégnaux (2,1), C. Eypert (3), P. Chapon (3), M. Bouttemy (2,1), A. Etcheberry (2,1)
Affiliations : (1) Institut Photovoltaïque d’Île de France (IPVF), 18 Boulevard Thomas Gobert, 91120 Palaiseau, France; (2) Institut Lavoisier de Versailles (UMR 8180), Université de Versailles-Saint-Quentin-en-Yvelines – CNRS, 45 avenue des États-Unis, 78035 Versailles, France ; (3) HORIBA Scientifique, 14 Boulevard Thomas Gobert - Passage Jobin Yvon CS 45002 91120 Palaiseau, France
Resume : Nowadays the development of tandem solar cells promotes the interest for III-V semiconductor materials. Such architecture evolutions of solar cells require an appropriate characterization strategy to accurately understand the chemical properties at the different interfaces constitutive of the heterojunction based device. Our methodology consists in reaching interfaces of interest quickly by Glow Discharge – Optical Emission Spectroscopy (GD-OES) and performing X-ray Photoelectron Spectroscopy (XPS) analyses directly inside the GD-OES crater. But the GD-OES profiling process and the Ar plasma sputtering stop lead to possible surface degradation of the explored material and re-deposition processes in the crater. The behavior of binary semiconductors (InP, GaAs and GaP) is compared to ternary ones (InGaAs, InGaP and AlGaAs). The GD-OES crater bottom is systematically studied to determine the possible perturbations of its surface chemistry, morphology, and optical signal (XPS, Auger, SEM-EBSD, ellipsometry). These techniques reveal the presence of a superficial damaged overlayer requiring to develop regeneration (chemical or physical) steps. Depending on the material, more or less pronounced modification of the crater roughness and composition are shown, as well as an amorphization. To complete this study, the surface chemical state obtained after GD-OES Ar plasma profiling is compared to the one obtained by ionic etching using Ar+ bombardment inside the XPS analysis chamber.
Authors : A. I. Popov and E. A. Kotomin
Affiliations : Institute of Solid State Physics, University of Latvia, Riga, Latvia E-mail: email@example.com
Resume : Already about 60 years ago, Levi and Dienes performed first studies of radiation damage in Al2O3 crystals caused by fast neutrons, and almost fifty years ago, Compton and Arnold measured the threshold energy to displace atoms by incident energetic electrons. At the Second International Conference on Radiation Effects in Insulators (Albuquerque, 1983), J.H. Crawford summarized in his report the work done by that time and discussed what we still did not know at all or not enough . In particular, he highlighted how scanty was our knowledge of interstitial defects. Since then, many attractive ideas have been suggested, and many precise experiments have been carried out. It is impossible to list all or even the most interesting and important of them in a single presentation (see, e.g., [2,3]). Therefore, in the present talk we will try to summarize only key results related to simple electron centers (F, F+ and their dimers, colloids) with a special attention to interstitial defects: their electronic structure, role and manifestations in the processes of thermal annealing of the F-type centers in Al2O3  and several other ionic oxides, such as MgO, MgAl2O4, ZnO, BeO and Y3Al5O12. We will also discuss the possible solution of the second puzzle, mentioned by Crawford, namely why and how the so-called hole V-type centers could be formed under optical transformation of the electron centers F+→ F in α-Al2O3 and MgO single crystals. Finally, we will discuss the process of the intrinsic high-temperature migration/transformation of F centers in ionic oxides and demonstrate how F-type dimer centers and metallic colloids could be formed as a part of the process .  J.H. Crawford, Nucl. Instrum. Meth. B 1 (1984) 159-165.  E.A. Kotomin and A.I. Popov, Nucl. Instrum. Meth. B 141 (1998) 1-15.  S.J. Zinkle and C. Kinoshita, J. Nucl. Mat. 251 (1997) 200-217.  A.I. Popov, A. Lushchik, et al. Nucl. Instrum. Meth. B 433 (2018) 93-97.  V.N. Kuzovkov, E.A. Kotomin, and A.I. Popov, J. Nucl. Mater., 502 (2018) 295-300.
Authors : Dechao Meng(1), Geng Li(2), Xiangyu Sun(1), Yu Song(1), Donghua Yue(3), Chenbowen Li(2), LiQiang Xu(4), Haoliang Huang(5), Feng Chen(4), Ke Wang(2), Yijia Du(1)
Affiliations : (1) Microsystem and Terahertz Research Center & Institute of Electronic Engineering, China Academy of Engineering Physics, Chengdu, 610200, China. (2) State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China (3) Institute of Systematical Engineering, China Academy of Engineering Physics, Mianyang, 621900, China. (4) Department of Physics, University of Sciences and Technology of China, and High Magnetic Field Laboratory, Chinese Academy of Sciences (CAS), Hefei 230026, China (5) National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, China
Resume : Prior work on gamma ray irradiation of functional materials has shown a direct correlation between total ionic dose (TID) and degradation of functional properties. Generally, the gamma ray would lead to charge traps generation/accumulation, and result in more deterioration than enhancement of the properties. Various methods have attempted to elucidate such process at both micro and macro scales. Some phenomenological models  have been developed to quantify defect interactions. Though it was also used to manipulate the performance of functional materials, gamma ray is far beyond effective engineering method, which seems to only cause degradations. Achieving obvious promotion and relatively precise prediction seems to be the main drawback in application of gamma ray defect engineering. Similar to the dose dependent dielectric constant, almost all the remnant polarizations (Pr) follow the monotonous degradation model  well, with a few exceptions [2-6]. These “strange” Pr firstly increased and then decreased in TID experiments, which could be well modeled using a modified Weibull`s rule  as ΔPr/Pr=1-exp(-a*x^(1-b)) c*x, where x means the irradiation dose. These results mainly obtained from poled samples indicate that the pristine piezoelectric states might contribute to the additional linear part and significantly influence the defect interaction and promote the radiation hardness. It initializes our further work about gamma ray in ferroelectric materials. Then great efforts have been taken in manipulation of pristine states to promote gamma ray as an effective defect engineering method, achieving both piezoelectric enhancement and degradation. High performance PbZr0.52Ti0.48O3 (PZT) films have been selected and fabricated on silicon based substrate at several micrometers. A perovskite structured bufferlayer of a few nanometers was optimized to stabilize the structures. Obvious Pr enhancements were confirmed even at different dose rate, but absent in a bulk ceramics and these films in reference with even similar composition but lower textured structures. It means that the pristine structural states play the similar role to bias in these exceptions. XRD, pole figure and SEM results suggest the films to be 99% highly textured, which stabilized a large remnant polarization without electrical bias. EBSD and STEM reveal a gradient evolution of grain orientation along the thickness. It might cause another internal field across the film confirmed by KPFM, which acts as a bias field and actually poles the films. In summary, we eventually achieve gamma ray defect engineering in ferroelectric metal oxides by manipulating the pristine sates in highly textured films, and develop a modified degradation model to predict the performance. It provides a new method that forgoes chemical doping and might benefit further advances in microelectronics and micro-electro-mechanical systems.  Sci. Rep. 7, 5308 (2017);  Phys. Rev. 184, 476 (1969);  IEEE T. Nucl. Sci, 37, 1703(1990);  IEEE T. Nucl. Sci, 37, 1713(1990); Thin Solid Films 562,185(2014);  J. Alloy. Compd., 152148 (2019)
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Materials I : Tiziana Cesca
Authors : C. Grygiel, A. Ribet, J. G. Mattei, H. Lebius, E. Balanzat, I. Monnet
Affiliations : CIMAP, Normandie Univ, ENSICAEN, UNICAEN, CEA, CNRS, 14000 Caen, France
Resume : Experiments at large-scale facilities as ion accelerators allow the simulations for materials of real working conditions such as radiative environments ranging from nuclear to space applications. Indeed, swift heavy ion irradiation leads mainly to the deposition of intense electronic excitations entailing defect formation and structural modifications that depend on material characteristics. Since few years the development of versatile laboratory X-Ray diffractometers allows high resolution in grazing geometry being suitable for the irradiated material characterizations where the upper irradiated part of samples might be strongly and non-homogeneously modified in depth. Damage depth profiles are thus established in irradiated materials by using combination of in-situ GIXRD, ex-situ HR-XRD, TEM and even UV-Vis absorption. In the presentation, an overview on defect formation and structural modifications (amorphization, strain, grain subdivision) associated to energy deposition processes (Se or Sn) induced by swift heavy ion irradiation in functional materials will be presented.
Authors : Matthew J. Lloyd, Robert G. Abernethy, Bethany Jim, Mark R. Gilbert, Ian Griffiths, Jack C. Haley, Paul A. J. Bagot, Enrique Martinez, Duc Nguyen-Manh, Michael P. Moody, David E. J. Armstrong
Affiliations : Department of Materials, University of Oxford and UKAEA; Department of Materials, University of Oxford and UKAEA; Department of Materials, University of Oxford; UKAEA; Department of Materials, University of Oxford; Department of Materials, University of Oxford; Department of Materials, University of Oxford; Theoretical Division, Los Alamos National Laboratory; UKAEA; Department of Materials, University of Oxford; Department of Materials, University of Oxford
Resume : The realisation of fusion energy is dependant on the development of resilient plasma facing materials that can withstand the combined effects of high energy neutron irradiation and high operating temperatures. Transmutation in these components leads to the production of Re and Os, and a composition that varies significantly with time . The precipitation of Re and Os, observed experimentally in both ion and neutron studies is a potential life limiting factor . In this research, neutron irradiated W was irradiated to 1.67dpa at 900oC, producing a post irradiation composition of W-1.4at.%Re-0.1at.%Os. Characterisation using a combination of Atom Probe Tomography (APT) and Scanning Tunnelling Electron Microscopy (STEM) found mostly voids decorated with both Re and Os, as well as smaller isolated precipitates. Grain boundaries were also decorated with both Re and Os. Experimental results were supported by a multicomponent, atomistic kinetic Monte Carlo model  incorporating both vacancy & interstitial defects, and solute concentration dependant interactions.  Gilbert, M.R. and Sublet, J.-C., Nuclear Fusion, 2011.  Lloyd, M.J., Abernethy, R.G., Gilbert, M.R., Griffiths, I., Bagot, P.A., Nguyen-Manh, D., Moody, M.P. and Armstrong, D.E., 2019. Scripta Materialia, 173, pp.96-100.  Lloyd, M.J., Abernethy, R.G., Armstrong, D.E., Bagot, P.A., Moody, M.P., Martinez, E. and Nguyen-Manh, D., 2019. The European Physical Journal B, 92(10), p.241.
Authors : 1Marie-Noëlle de Noirfontaine, 2Enric Garcia – Caurel, 2Daniel Funes-Fernando, 1,3Jihane Jdaini, 4Sandrine Tusseau – Nenez, 1,5Mireille Courtial, 1Frédéric Dunstetter, 3Céline Cau – dit –Coumes, 1Dominique Gorse – Pomonti
Affiliations : 1Laboratoire des Solides Irradiés, Ecole Polytechnique, CNRS UMR 7642, CEA-DSM-IRAMIS, IP Paris, F-91128 Palaiseau Cedex, France 2Laboratoire de Physique des Interfaces et des Couches Minces, UMR CNRS 7647, Ecole Polytechnique,IP Paris, F-91128 Palaiseau Cedex, France 3Laboratoire d’études des Ciments et Bitumes pour le Conditionnement (LCBC) - CEA-DEN, DE2D/SEAD/LCBC - Marcoule, F-30207 Bagnols-sur-Cèze, France 4 Laboratoire de Physique de la Matière Condensée, UMR CNRS 7643, Ecole Polytechnique, IP Paris, F-91128, Palaiseau Cedex 5Université d’Artois, 1230 Rue de l’Université, F-62408 Béthune, France
Resume : Brushite CaHPO4.2H2O (Dicalcium Phosphate Dihydrate: DCPD) is considered as a sorbent of strontium (90Sr2+) which is a contaminant present in some acidic effluents produced by cleaning operations during the dismantling of former nuclear facilities. The idea is to check how electron - radiation - sensitive is this material, since structural and chemical changes caused by irradiation might affect significantly its ion exchange capacity. The energy deposited by the projectile electron into the target is known to be approximated as the sum of two contributions, ballistic and electronic. But only their order of magnitude is supposed to be known. As a result, the structural damage caused by electron irradiation cannot be even reasonably estimated and the radiation sensitivity of brushite has to be checked experimentally. In this paper, powder X-ray diffraction and Raman spectroscopy are associated to analyze the damage effects to brushite following electron irradiation. The accelerator NEC Pelletron of the SIRIUS platform is used for electron irradiation at 2.5 MeV (dose rate of order 20 kGy/s). Amorphization of brushite is observed with increasing dose, and was found complete at 6 GGy. The Raman spectroscopy study tells us that the ultimate compound at the highest dose could be of type anhydrous pyrophosphate. Consequences regarding the damage mechanisms are considered.
Authors : Roger Smith
Affiliations : School of Science, Loughborough University, LE11 3TU, UK
Resume : Both borosilicate and iron phosphate glasses are used for the encapsulation of high level nuclear waste. A description of how atomistic models can be used, together with molecular dynamics simulations of radiation damage in these glasses to understand the damage processes and to explain why glasses are an especially good choice for waste encapsulation. In the case of crystals the amount of damage produced by an irradiation event is usually categorised by the number of Frenkel pairs produced but this cannot be used in the case of a glass. It will be shown that a useful concept instead is the change in atomic co-ordination induced by the collision cascade. It will also be demonstrated how some modern simulation techniques can be used to determine how the glasses relax over times scale longer than those generally accessible by molecular dynamics.
Authors : J.-F. Barbot, M.-F. Beaufort, A. Boulle, A. Declémy
Affiliations : Institut Pprime, Département Physique et Mécanique des Matériaux, CNRS-Université de Poitiers, ENSMA, TSA 41123, 86073 Poitiers Cedex 9 Institut de Recherche sur les Céramiques, CNRS UMR 7315, Limoges, France
Resume : Single crystals of 4H-SiC were implanted by noble gases under different conditions (fluence and temperature). The elastic strain buildup was particularly studied at elevated temperature for which the dynamical recombination prevents the amorphous transition. A phenomenological model based on Multi-Step-Damage Accumulation (MSDA) and cascade recovery (Gibbon's model) allows to fit the evolution of the maximal elastic strain according to the fluence and for different temperatures of implantation. In addition, with the help of transmission electron microscopy the evolution of the implantation related defects under annealing was studied. The formation of nanocavities was observed under severe implantation/annealing conditions of Xe implantation. These cavities are found of different nature according to the xenon and damage distribution as well as the related-strain profile (obtained by the simulations of the XRD curves). The surface swelling (step height) under implantation/annealing was also studied leading to different activation energies supporting the idea of different defects contributions to swelling.
Modelling of damage and defects II : Chairman to be defined
Authors : Daniel Mason, Andrea Sand, Sergei Dudarev
Affiliations : CCFE, Culham Centre for Fusion Energy, Abingdon, Oxfordshire OX14 Q3DB, United Kingdom; Department of Physics, University of Helsinki, PO Box 43, FI-00014, Helsinki, Finland; CCFE, Culham Centre for Fusion Energy, Abingdon, Oxfordshire OX14 Q3DB, United Kingdom
Resume : The theoretical basis of object kinetic Monte Carlo, and many related methods, is that the current state of the system consists of set of spatially discrete objects- point defects, dislocation loops and voids - which may evolve and interact with each other with predefined rules. An object is typically described with a small number of parameters - for instance a void may be defined by the number of vacancies contained, but there is no reason why additional shape information should not be retained if such information is useful. The logical limit of the amount of information retained per object is a description of the atomic types and positions. We describe the development of a new object kinetic Monte Carlo code where the elementary defect objects are off-lattice atomistic configurations. An object evolves by internal rearrangements of the atoms, which can be found on-the-fly. Such rearrangements typically transform one object into another, but can also involve displacement of the centre-of-mass, or splitting one object into two. Elastic interactions are handled with interatomic potentials within an object, and with the dipole tensor formalism between objects. We track visited configurations to build up a relevant database of objects plus events. Once a good database is found we can evolve mobile interstitial clusters faster than the equivalent MD simulation, even at high temperature. We apply the model to the evolution of 20 keV PKA cascades in tungsten, and capture complex internal relaxations of sessile objects instigated by object collisions. These cascades are evolved to experimental timescales at technologically relevant temperatures 600-900 K. We discuss the lessons learnt and the challenges for modelling irradiation damage evolution with object kinetic Monte Carlo. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under grant agreement No. 633053, and from the RCUK Energy Programme [grant number EP/P012450/1]. The views and opinions expressed herein do not necessarily reflect those of the European Commission. AES acknowledges support from the Academy of Finland through project No. 311472.
Authors : Pavlos Mouratidis, James McHugh, Kenny Jolley, Malcolm Heggie, Patrick Briddon
Affiliations : Loughborough University Department of Chemistry;Loughborough University Department of Chemistry;Loughborough University Department of Chemistry;Loughborough University Department of Chemistry;Newcastle University School of Engineering
Resume : Graphite has been the material of choice in construction of nuclear reactors for many years due to its low neutron absorption cross-section and high scattering cross-section. The physical properties of a graphite moderator can greatly influence the cost, safety and lifespan of a reactor. Neutron collision damage in graphite results in the formation of basal dislocations. The subsequent interaction of basal dislocations with each other and the surrounding lattice causes severe dimensional changes along the basal direction. There has been a lot of interest recently in AB and AC stacking grain boundaries in bilayer graphene. Transition from AB to AC stacking can be described by the glide of partial basal dislocations resulting in expansion of dislocation cores and buckling of the bilayer. Herein we present full ab initio and molecular dynamics calculations of basal dislocation network structures in bilayer graphene and few-layer graphene in large supercells of up to 100 nm.
Authors : Gonzalo Valles, Carlo L. Guerrero, Fernando Jiménez, Christophe J. Ortiz
Affiliations : Laboratorio Nacional de Fusión por Confinamiento Magnético-CIEMAT, Spain
Resume : Owing to their properties, reduced-activation ferritic/martensitic (RAFM) steels are proposed as structural materials for in-vessel components of future fusion reactors. Neutron irradiation produces defects in the material, leading to detrimental effects on its mechanical properties such as hardening and embrittlement. Dislocation mobility, which is related to the mechanical behaviour of the material, is highly influenced by the defects created due to neutron/ion irradiation. Moreover, it has been reported that dislocations have an influence on the spatial distribution of defects in bcc iron. Elastic interactions between dislocations and SIA clusters lead to dislocation decoration and to an inhomogeneous spatial distribution of SIA clusters. In this work, we present a study of the influence of spatial defect distribution on dislocation mobility in the case of self-ion irradiation on bcc iron. For this purpose, defect distribution in the presence of dislocations is calculated by MEGA code, an object kinetic Monte Carlo code based on GPU programming which allows the study of high irradiation doses, large spatial regions and elastic interactions between SIA clusters and dislocations. Dislocation mobility in the presence of defects, either placed at random positions or at those positions previously calculated by okMC, is studied by means of Dislocation Dynamics technique with MoDELib suit of codes.
Authors : López, P.*(1), Aboy, M.(1), Muñoz, I.(1), Santos, I.(1), Marqués, L.A.(1), Couso, C.(2), Ullán, M.(2) & Pelaz L.(1)
Affiliations : (1) Departamento de Electricidad y Electrónica, Universidad de Valladolid, ETSI Telecomunicación, Paseo de Belén 15, 47011 Valladolid, Spain (2) Centro Nacional de Microelectrónica (IMB-CNM, CSIC), Campus UAB, 08193 Bellaterra, Barcelona, Spain
Resume : Si detectors built on p-type substrates are suitable for high energy physics applications due to their improved radiation hardness. However, they are still strongly affected by irradiation-induced displacement damage, as it alters the net space charge. It has been reported that the effective doping concentration (Neff) undergoes a fast decay for low neutron fluences, attributed to an acceptor removal process, and that the removal rate decreases as the initial dopant concentration increases. This process is associated to dopant deactivation by damage, but its microscopic origin and the reason for the rate dependence on resistivity are still unknown. We use atomistic simulations to analyze the acceptor removal process in samples with B concentrations ranging from 1013 to 1017 cm-3, irradiated up to 1016 cm-2 1-MeV neq fluences. Si recoils are simulated within a binary collision approximation scheme, following the energy distribution of primary knock-on atoms calculated with the SPECTRA-PKA code. The subsequent dopant-defect interactions are simulated with a kinetic Monte Carlo code with detailed models of defect and dopant diffusion, as well as dopant deactivation. The simulated Neff dependence on fluence and the obtained removal rates are consistent with experiments. Through the analysis of defect-dopant interactions we will shed light on the atomistic mechanisms responsible for the acceptor removal process, and will explain some intriguing features not understood until now.
Authors : Abner Velazco Torrejón, Armand Béché, Johan Verbeeck
Affiliations : EMAT, Antwerp University, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
Resume : The current strategies to reduce beam damage in a transmission electron microscope (TEM) consists in reducing the electron dose, calculated in electrons per area (usually given in square angstrom), that is delivered to the sample either by decreasing the electron beam current or making fast acquisitions of images, resulting in low signal-to-noise ratio images. A new approach from the field of data compression has been proposed to overcome or alleviate the problem of beam damage in TEM. The so-called compressed sensing technique is based on a sub-sampling approach where the information can be retrieved from a reduced data acquisition . In STEM (Scanning TEM) mode, with compressed sensing is possible to retrieve an image scanning a fewer number of pixels than with normal acquisition. This non-conventional method of dose reduction has been recently implemented in STEM [2,3] and it has showed the possibility of atomic-resolution imaging of beam sensitive materials . As with this sub-sampling technique the sample is not irradiated consecutively, we proposed that a dissipation of a dynamic process of beam damage could be involved in damage reduction when the dose is accumulated at a slower rate than the diffusion of this process. Charging or heating of the sample would follow these model, for instance. In the conventional raster scanning where the probe is scanned across the sample line by line, the dose is accumulated in a consecutive order. If only the order of the scanning positions is modified, skipping a fixed number of pixels between two scanning positions in a line and scanning the missing pixels after completing all the scan lines, for instance, the dose in the surrounding area of a specific point in the sample would be accumulated at a different time rate than with the raster scanning. If any dynamic mechanism is involved, this strategy could dissipate or reduce damage on the sample. With the help of a programmable scan engine different alternative scanning strategies were tested on a beam sensitive sample (commercial Linde type A Zeolite) where the total electron dose was kept constant but its temporal distribution modified. Our results showed less damage when scanning in a different order than raster scanning. These findings demonstrate that the way how the dose is distributed plays an important role on beam damage which gave some insights about the mechanism which can be modelled by a diffusion process. Diffusion simulations can be useful to find a suitable scanning strategy according to the sample characteristics to outrun beam damage in STEM.  Candes E. J., Romberg J. K. and Tao T., Communications on Pure and Applied Mathematics, 59, 1207-1223 (2006).  Béché, A., Goris, B., Freitag, B., Verbeeck, J., Appl. Phys. Lett. 2016, 108, 093103.  A. Stevens, L. Luzi, H. Yang, L. Kovarik, B. Mehdi, A. Liyu, M. Gehm, and N. Browning, Appl. Phys. Lett. 112, 043104 (2018).
Authors : M. Scepanovic, M. A. Auger, T. Leguey, V. de Castro
Affiliations : Universidad Carlos III de Madrid
Resume : One of the main structural candidate materials for advanced nuclear fusion reactors over the last decade are oxide dispersed strengthened reduced activation ferritic steels (ODS RAFS). A fine, homogeneous, dispersion of stable nanoparticles such as Y2O3 would allow increasing their upper operating temperatures and radiation damage resistance. However, currently available results require further research to clarify the effect of irradiation on these materials. The main objective of this work is to investigate the microstructural stability of different ODS RAFS with nominal composition Fe–14Cr–2W–0.3Ti–0.3Y2O3 (wt%) subjected to simultaneous dual (Fe3+, He+) ion irradiation at 400 °C to 30 dpa. The characterization of the steels has been accomplished using Transmission electron microscopy (TEM), Atom Probe Tomography (APT) and Positron Annihilation Spectroscopy (PAS). The stability of the nanoparticles has been investigated. The irradiation induced damage has been characterized, focusing in the study of open volume defects. There is a slight change in the chemical composition of nanoparticles after irradiation. The mean size and mean distance of nanoclusters is lower after the irradiation pointing to dissolution of larger nanoclusters and nucleation of new, smaller ones. PAS investigations show a limited increase of open volume defects after the irradiation suggesting a possible entrapment of all injected He ions into the open-volume defects simultaneously created by the Fe irradiation or/and recombination of vacancies and interstitials due to the intermediate temperature of the irradiation. CDB profiles show no clear relation between positron traps and He.
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|08:45||PLENARY SESSION 2|
Authors : Lin JUN (1), Guillaume TOQUER (1), Sandrine DOURDAIN (1), Clara GRYGIEL (2), Xavier DESCHANELS (1)
Affiliations : (1) ICSM, CEA, CNRS, Univ Montpellier, Marcoule, France; (2) Centre de Recherche sur les Ions, les matériaux et la photonique, CEA-DSM-IRAMIS-CIMAP BP 5133 14 070 Caen Cedex 5, France
Resume : Mesoporous silicas have been proposed for the treatment of radioactive effluents by a new strategy called separation / conditioning. This strategy would allow both the separation of the radionuclide using a selective organic ligand, and its encapsulation after collapse of the porosity by “soft” way (sol-gel reaction, heating under stress or irradiation) to obtain a primary wasteform matrix. This low temperature process would be particularly interesting for the treatment of radioactive effluents containing volatile elements (Cs, I). The talk reports recent results on the dimensional change and the collapse of mesoporous silica pellets under electron beams (2MeV) representative of the beta decay of Cs. The irradiated samples were analyzed by density measurement, Small Angle X-Rays (SAXS), nitrogen adsorption-desorption isotherms to evaluate the evolution of the mesoporous network and Nuclear Magnetic Resonance (NMR), infrared spectroscopy (IR) for the silica network. A mechanism will be proposed to explain the evolution of the mesoporous structure under irradiation. P. Makowski, X. Deschanels, A. Grandjean, D. Meyer, G. Toquer and F. Goettmann, New J. Chem., 2012, 36, 531. Y. Lou, S. Dourdain, C. Rey, Y. Serruys, D. Siméone, N. Mollard, X. Deschanels, Micropor. Mesopor. Mater, 2017, 251, 146.
Authors : F. Bergner, M. Hernández-Mayoral, L. Malerba, M.J. Konstantinović, C. Pareige
Affiliations : Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden, Germany; Division of Materials, CIEMAT, Avenida Complutense 40, 28040 Madrid, Spain; SCK•CEN, Nuclear Material Science Institute, Boeretang 200, B–2400 Mol, Belgium; Groupe de Physique des Matériaux, Université et INSA de Rouen, UMR 6634 CNRS, Avenue de l’Université, BP 12, 76801 Saint Etienne du Rouvray, France
Resume : One of the open issues concerning the quantitative understanding of irradiation hardening in Cr steels is related to the spatial arrangement of irradiation-induced dislocation loops with respect to pre-existing dislocations and its consequences for irradiation hardening. In order to tackle this issue, a number of neutron-irradiated industrial-purity Fe-Cr alloys (Cr between 2.5 and 12%) was studied by means of TEM. Loops in irradiated Fe-Cr alloys of lower Cr content were found to arrange more homogeneously in the matrix. In contrast, loops tend to arrange preferentially along dislocation lines for higher Cr contents [Hernandez-Mayoral et al., JNM 474 (2016) 88]. At the same time, reported tensile stress-strain curves [Matijasevic et al., JNM 377 (2008) 147] exhibit trends from smooth elastic-plastic transitions towards yield drops for both increasing Cr and increasing neutron exposure with an exception to be discussed. The poster is aimed to rationalize both observations, namely dislocation decoration at the nm length scale and yield effects at the macroscale, on the basis of the source hardening model [Trinkaus et al., JNM 251 (1997) 172]. In particular, calculated unlocking stresses are found to correlate with measured values of the upper yield stress.
Authors : Matteo Vanazzi, Boris Paladino, Jing Hu, Wei-Ying Chen, Meimei Li, Marco G. Beghi, Fabio Di Fonzo.
Affiliations : Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia, Via Pascoli 70/3, 20133 Milano (MI), Italy; Energy Department, Politecnico di Milano, Via Ponzio 34/3, 20133 Milano (MI), Italy; Nuclear Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois, USA.
Resume : Future generation nuclear reactors present intrinsic benefits in terms of economics, safety and waste management. However, innovative material strategies must be designed. Recently, coatings have earned great attention in the nuclear field as a reliable cost-efficient solution. In this framework, amorphous/nano-crystalline oxides have been characterized as corrosion-resistant anti-diffusion barriers. Previously, oxide films have been tested under ion irradiation, proving high stability up to 150 dpa. This radiation tolerance has been related to the amorphousness of the pristine material, which evolves towards a crystalline structure under irradiation. To preserve the radiation tolerance and improve the range of operation, the amorphous state must be conserved as long as possible. In this work, the stabilization of traditional oxides by doping is discussed. Firstly, pure and doped materials have been compared by thermal annealing, showing a significant increase in the crystallization temperature of the mixed systems. Then, irradiation tests have been performed with in situ TEM. Samples have been irradiated with different ions, up to 20 dpa. Experiments have been conducted at 600 °C and at 800 °C, to observe the effects of temperature on the radiation induced crystallization. Dopants retard the crystallization threshold even under irradiation and stabilize the intermediate metastable phases, conserving partially the pristine characteristics. While pure systems suffer from voids formation after crystallization (a traditional phenome for bulk oxides), no swelling appears in the doped counterpart.
Authors : Shengli Chen (1,2,*), David Bernard (1), Léonie Tamagno (1,#) & Olivier Litaize (1)
Affiliations : (1) CEA, DEN, DER, SPRC, LEPh, 13108 Saint-Paul-Lez-Durance, France (2) Université Grenoble Alpes, I-MEP2, 38402 Saint Martin d'Hères, France (#) Current address at CEA, DEN, DTN, SMTA, LMN, 13108 Saint-Paul-Lez-Durance, France
Resume : The mechanical and thermal property change of materials under irradiation is an important challenge for nuclear materials. For a typical Pressurized Water Reactor (PWR), radiation damage of the Reactor Pressure Vessel (RPV) is one of the most important issues that determine the operating lifetime of a reactor. Accurate calculation with realistic uncertainty estimates of radiation damage is thus of great importance. In nuclear reactors, radiation damage of materials is mainly induced by energetic neutrons. The accurate uncertainty quantification of neutron radiation damage requires thus the complete covariance matrix of damage cross section and the covariance matrix of neutron flux spectrum. Covariance matrices of different Prompt Fission Neutron Spectra (PFNS) of 235U are propagated to the neutron flux spectra in a simplified PWR RPV (such as the examples shown in Ref. ). Covariance matrix of damage cross section is propagated from nuclear reaction model parameters and primary damage model parameters. The total uncertainties of neutron-induced displacement damage from both the uncertainties of PFNS and the uncertainty of damage cross section are deduced using the so-called “sandwich” formula. In addition to the calculation of total uncertainty of primary radiation damage in the RPV, Primary Knock-on Atom (PKA) spectra and the corresponding covariance matrices are obtained by considering the covariance matrix of neutron flux spectra (but without considering the uncertainties from nuclear reaction data). These PKA spectra and the associated covariance matrices can be used together with molecular dynamics or binary collision approximation simulations to accurately determine the radiation damage and the corresponding uncertainty. Using the standard Norgett-Robinson-Torrens formula, numerical results show that the complete covariance matrices of neutron flux (resulting from covariance matrices of PFNS) lead to about 4% relative uncertainty (depending on different PFNS) for the atomic displacement damage of the RPV, whereas only 1% uncertainty is obtained if the correlations of neutron flux spectra in the RPV at different energies are not considered for generating the PKA spectra.  L. Berge, “Contribution à la modélisation des spectres de neutrons prompts de fission. Propagation d’incertitudes sur un calul de fluence cuve,” PhD thesis, Université Grenoble Alpes, 2015.
Authors : R. E. Schäublin1,2, V. Vojtech1, S. Küchler1, S. S. A. Gerstl1,2, J. F. Löffler1
Affiliations : 1 Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland 2 Scientific Center for Optical and Electron Microscopy, ETH Zurich, 8093 Zurich, Switzerland
Resume : Ferritic steel is one of the most promising candidate structural material of future fusion reactors. The extreme conditions when exposed to the fusion plasma, with high temperatures and 14 MeV fusion neutron irradiation, lead to a microstructural modification that impacts properties. Besides the generation of dislocation loops and cavities, there is Cr-rich α' precipitation, which leads to hardening and embrittlement, as well as changes in magnetic properties. In order to better understand and model its evolution a detailed description of its structure is needed. Fe-Cr model alloys are used to understand the fundamental mechanisms at play. Fe-20Cr (in wt.%) were considered in this work, with a thermally-driven decomposition induced by an anneal at 500 °C that leads to a high number density of α' precipitates that are few nanometers in diameter. The α' precipitates’ structure, composition and interface with the matrix were investigated using high-end transmission electron microscopy correlated to atom probe tomography and supported by molecular dynamics simulations.
Authors : Juan Pablo Balbuena, Maria Jose Caturla
Affiliations : Department of Applied Physics, University of Alicante (SPAIN)
Resume : In a recent study we addressed the formation mechanisms of <100> loops in pure iron. In this model, the migration of the loops did not depend on the local environment. In fact, <100> loops were considered immobile while ½<111> loops migration followed an Arrhenius law using some predefined prefactors and migration barriers depending on their size. With the present study we want to move a step forward by considering long range interactions between dislocation loops of any size. Expressions for elastic interactions between dislocation loops derived from Dudarev et al. are included into our custom version of the kinetic Monte Carlo code MMonCa. Preliminary calculation show that, for high enough concentrations of loops, the mobility is biased by the presence of the other loops. We plan to perform simulations in irradiated pure iron to explore and evaluate the effects of such interactions into the one dimensional migration of ½<111> loops. In a last instance we plan to compare our results with those obtained by Arakawa et al. who obtained activation energies for loop diffusion of 1.3 eV, independent of the loop size, value that is one order of magnitude higher than that obtained with molecular dynamics simulations. This first approach in using elastic interactions are not accounting for thermally fluctuating small changes in the direction of the Burgers vector, as predicted by Boleininger e et al.
Authors : Karthik Guda Vishnu, Alejandro Strachan
Affiliations : School of Materials Engineering, Purdue University
Resume : Radiation hard microelectronic components are essential for aeronautics and space applications and the reduced feature sizes at advanced technology nodes make these devices more susceptible to failure due to irradiation. Our objective is to investigate the atomic-level mechanisms of irradiation-induced defect generation in semiconductor/dielectric heterostructures relevant for FinFETs and nanosheet transistors. We focus on the initial generation of radiation cascades and the annealing that takes place over the first tens of picoseconds using large-scale molecular dynamics simulations using accurate reactive interatomic potentials. We modeled Si/amorphous-SiO2 heterostructures and considered 10 keV Si and O primary knock-on atoms. A detailed analysis of the MD trajectories enabled us to characterize displaced atoms and defective ones. As could be expected, we find that the Si/SiO2 interfaces acts as sinks for O defects but, quite surprisingly, Si defects accumulate at interfaces and preferentially anneal in the bulk SiO2 and Si regions.
|18:30||AWARD CEREMONY followed by SOCIAL EVENT|
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|08:45||PLENARY SESSION 3|
No abstract for this day
Ceramics Research Institute - 12, rue Atlantis, 87068 Limoges, France+33 5 87 50 23 82
Laboratorio Nacional de Fusión por Confinamiento Magnético - Avenida Complutense, 40, 28040, Madrid, Spain+34 914 96 25 82
Department of Materials Science and Engineering, 2300 Hayward St, Ann Arbor, MI 48109, USA+1 734 764 8717
Dipartimento di Fisica e Astronomia "G. Galilei" - Via Marzolo, 8, I-35131 Padova, Italy39 0498277044