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1. Stress Corrosion Cracking in Amorphous Phase Separated Oxide Glasses: A Holistic Review of Their Structures, Physical, Mechanical and Fracture Properties

Author

Weiying Feng, Daniel Bonamy, Fabrice Célarié, Paul C. M. Fossati, Stéphane Gossé, Patrick Houizot, and Cindy L. Rountree

Subjects
sodium borosilicate glasses, amorphous phase separation, miscibility gap, physical properties, mechanical properties, dynamic fracture, Chemical technology, TP1-1185
Abstract

Stress corrosion cracking is a well-known phenomenon in oxide glasses. However, how amorphous phase separation (APS) alters stress corrosion cracking, and the overall mechanical response of an oxide glass is less known in literature. APS is a dominant feature concerning many multicomponent systems, particularly the ternary sodium borosilicate (SBN) glass systems. Its three constituent oxides have significant industrial relevance, as they are the principal components of many industrial oxide glasses. Simulations and experimental studies demonstrate the existence of a two-phase metastable miscibility gap. Furthermore, theory suggests the possibility of three-phase APS in these oxide glasses. Literature already details the mechanisms of phase separation and characterizes SBN microstructures. Realizing that glasses are structurally sensitive materials opens a number of other questions concerning how the mesoscopic APS affects the continuum behavior of glasses, including dynamic fracture and stress corrosion cracking. This paper reviews current literature and provides a synthetic viewpoint on how APS structures of oxide glasses alter physical, mechanical, dynamic fracture, and stress corrosion cracking properties.

Published
2021
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3. Effect of architecture disorder on the elastic response of two-dimensional lattice materials

Author

Antoine Montiel, Thuy Nguyen, Cindy L. Rountree, Valérie Geertsen, Patrick Guenoun, Daniel Bonamy, Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Research Center [Pôle Universitaire Léonard de Vinci] (DVRC), De Vinci Research Center, Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire (LIONS), Nanosciences et Innovation pour les Matériaux, la Biomédecine et l'Energie (ex SIS2M) (NIMBE UMR 3685), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), CEA PTC Materiaux & Procédés, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Pôle Universitaire Léonard de Vinci (PULV), The CEA PTC Materiaux & Procédés(project lightToughMetaMat), and Palacin, Serge

Subjects
[CHIM.MATE] Chemical Sciences/Material chemistry, Condensed Matter - Materials Science, beam model, 78.55.Qr elasticity, random lattice, PACS numbers: 46.50.+a,62.20.M-,78.55.Q, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, [CHIM.MATE]Chemical Sciences/Material chemistry, elastic constants, Condensed Matter - Soft Condensed Matter, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], [PHYS.MECA.MEMA] Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], numerical simulation, numbers: 46.50.+a, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Soft Condensed Matter (cond-mat.soft), elasticity, 62.20.M
Abstract

International audience; We examine how disordering joint position influences the linear elastic behavior of lattice materials via numerical simulations in two-dimensional beam networks. Three distinct initial crystalline geometries are selected as representative of mechanically isotropic materials low connectivity, mechanically isotropic materials with high connectivity, and mechanically anisotropic materials with intermediate connectivity. Introducing disorder generates spatial fluctuations in the elasticity tensor at the local (joint) scale. Proper coarse-graining reveals a well-defined continuum-level scale elasticity tensor. Increasing disorder aids in making initially anisotropic materials more isotropic. The disorder impact on the material stiffness depends on the lattice connectivity: Increasing the disorder softens lattices with high connectivity and stiffens those with low connectivity, without modifying the scaling between elastic modulus and density (linear scaling for high connectivity and cubic scaling for low connectivity). Introducing disorder in lattices with intermediate fixed connectivity reveals both scaling: the linear scaling occurs for low density, the cubic one at high density, and the crossover density increases with disorder. Contrary to classical formulations, this work demonstrates that connectivity is not the sole parameter governing elastic modulus scaling. It offers a promising route to access novel mechanical properties in lattice materials via disordering the architectures.

Published
2022
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4. Stress Corrosion Cracking in Amorphous Phase Separated Oxide Glasses: A Holistic Review of Their Structures, Physical, Mechanical and Fracture Properties

Author

F. Celarie, Stéphane Gossé, Patrick Houizot, Daniel Bonamy, Cindy L. Rountree, Weiying Feng, Paul C. M. Fossati, Université Paris-Saclay, CEA- Saclay (CEA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UNIV-RENNES), Service de la Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME), Département de Physico-Chimie (DPC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, DIM-MAP AFM4aStory, ANR-17-CE08-0004,ToughGlasses,Amélioration de la réponse des verres d'oxydes à la Corrosion Sous Contrainte (CSC)(2017), Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Spinodal decomposition, Oxide, 02 engineering and technology, TP1-1185, mechanical properties, 01 natural sciences, physical properties, chemistry.chemical_compound, Metastability, 0103 physical sciences, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], Composite material, Stress corrosion cracking, sodium borosilicate glasses, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, [PHYS]Physics [physics], Borosilicate glass, miscibility gap, Chemical technology, dynamic fracture, General Medicine, 021001 nanoscience & nanotechnology, Microstructure, stress corrosion cracking, chemistry, amorphous phase separation, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], Fracture (geology), 0210 nano-technology, Ternary operation
Abstract

International audience; Stress corrosion cracking is a well-known phenomenon in oxide glasses. However, how amorphous phase separation (APS) alters stress corrosion cracking, and the overall mechanical response of an oxide glass is less known in literature. APS is a dominant feature concerning many multicomponent systems, particularly the ternary sodium borosilicate (SBN) glass systems. Its three constituent oxides have significant industrial relevance, as they are the principal components of many industrial oxide glasses. Simulations and experimental studies demonstrate the existence of a two-phase metastable miscibility gap. Furthermore, theory suggests the possibility of three-phase APS in these oxide glasses. Literature already details the mechanisms of phase separation and characterizes SBN microstructures. Realizing that glasses are structurally sensitive materials opens a number of other questions concerning how the mesoscopic APS affects the continuum behavior of glasses, including dynamic fracture and stress corrosion cracking. This paper reviews current literature and provides a synthetic viewpoint on how APS structures of oxide glasses alter physical, mechanical, dynamic fracture, and stress corrosion cracking properties

Published
2021
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5. Conductivity via Thermally Induced Gap States in a Polyoxometalate Thin Layer

Author

Cindy L. Rountree, Amanda Generosi, Barbara Paci, Anna Proust, Qirong Zhu, Claire Mathieu, Nicholas Barrett, Guillaume Izzet, Pierre Gouzerh, Séverine Renaudineau, Ludovic Tortech, Xihui Liang, Institut Parisien de Chimie Moléculaire (IPCM), Chimie Moléculaire de Paris Centre (FR 2769), Institut de Chimie du CNRS (INC)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Innovation en Chimie des Surfaces et NanoSciences (LICSEN), Nanosciences et Innovation pour les Matériaux, la Biomédecine et l'Energie (ex SIS2M) (NIMBE UMR 3685), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Consiglio Nazionale delle Ricerche [Roma] (CNR), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), DIM NanoK, région Ile de France, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Innovation en Chimie des Surfaces et NanoSciences (LICSEN UMR 3685), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR)

Subjects
Materials science, Photoemission spectroscopy, 02 engineering and technology, Conductivity, 010402 general chemistry, 7. Clean energy, 01 natural sciences, Polyoxometalate Thin Layer, Physical and Theoretical Chemistry, Electrical conductor, Deposition (law), business.industry, Thermally Induced Gap- States, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Thermal conduction, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Characterization (materials science), General Energy, Polyoxometalate, Optoelectronics, 0210 nano-technology, business, Layer (electronics)
Abstract

International audience; We report a study of alpha-[P2W18O62]6-, Wells-Dawson polyoxometalate layers deposited on ITO coated glass substrates. A variety of techniques has been used including atomic force microscopy for surface topography characterization, current mapping and current-voltage characteristics, X-ray photoemission spectroscopy for chemical analysis, UV-visible photoemission spectroscopy for determination of band line-ups and energy dispersive X-ray reflectivity for determination of layer thicknesses and scattering length densities. The conditions of film deposition and subsequent thermal annealing strongly affect the film characteristics. In particular, we show that nanostriped films a few tens of nm thick can be obtained in a reproducible manner and that such structuring is accompanied by the appearance of gap-states and by a switch from an insulating to a conductive state. Current-voltage characteristics demonstrate that highly ordered films of K 6 [P 2 W 18 O 62 ] allow electron flow only from ITO to [P2W18O62]6-, thus showing a rectifying effect. Finally, we integrate the POM layer 2 into an organic photovoltaic device and show the conduction through it thanks to favorable band alignment between ITO, the gap states and the active photovoltaic layers.

Published
2019
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6. Roughness of oxide glass subcritical fracture surfaces

Author

Frederic Lechenault, Matthieu George, Matteo Ciccotti, Cindy L. Rountree, Cédric Ottina, Gaël Pallares, Elisabeth Bouchaud, Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS (LPS), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Gulliver (UMR 7083), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique de l'ENS Lyon (Phys-ENS), École normale supérieure - Lyon (ENS Lyon)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, Sciences et Ingénierie de la Matière Molle (SIMM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Sciences et Ingénierie de la Matière Molle (UMR 7615) (SIMM), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, FOS: Physical sciences, 02 engineering and technology, Surface finish, Condensed Matter - Soft Condensed Matter, 01 natural sciences, Root mean square, Crack closure, 0103 physical sciences, Materials Chemistry, Surface roughness, Forensic engineering, surface, Coupling (piping), Composite material, 010306 general physics, Stress intensity factor, roughness, glass, Fracture mechanics, 021001 nanoscience & nanotechnology, fracture, Ceramics and Composites, Fracture (geology), Soft Condensed Matter (cond-mat.soft), 0210 nano-technology, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Abstract

International audience; An original setup combining a very stable loading stage, an atomic force microscope and an environmental chamber, allows to obtain very stable sub-critical fracture propagation in oxide glasses under controlled environment, and subsequently to finely characterize the nanometric roughness properties of the crack surfaces. The analysis of the surface roughness is conducted both in terms of the classical root mean square roughness to compare with the literature, and in terms of more physically adequate indicators related to the self-affine nature of the fracture surfaces. Due to the comparable nanometric scale of the surface roughness, the AFM tip size and the instrumental noise, a special care is devoted to the statistical evaluation of the metrologic properties. The 2 roughness amplitude of several oxide glasses was shown to decrease as a function of the stress intensity factor, to be quite insensitive to the relative humidity and to increase with the degree of heterogeneity of the glass. The results are discussed in terms of several modeling arguments concerning the coupling between crack propagation, material's heterogeneity, crack tip plastic deformation and water diffusion at the crack tip. A synthetic new model is presented combining the predictions of a model by Wiederhorn et al. [1] on the effect of the material's heterogeneity on the crack tip stresses with the self-affine nature of the fracture surfaces.

Published
2017
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7. Role of particle aggregation on the structure of dried colloidal silica layers

Author

Georges Gauthier, Arnaud Lesaine, Véronique Lazarus, Marianne Impéror-Clerc, Cindy L. Rountree, Daniel Bonamy, Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Fluides, automatique, systèmes thermiques (FAST), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des Solides (LPS), Institut des Sciences de la mécanique et Applications industrielles (IMSIA - UMR 9219), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), ANR-11-IDEX-0003,IPS,Idex Paris-Saclay(2011), ANR-10-LABX-0032,LaSIPS,LABORATORY FOR SYSTEMS AND ENGINEERING OF PARIS SACLAY(2010), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-EDF R&D (EDF R&D)

Subjects
Materials science, Colloidal silica, Dispersity, FOS: Physical sciences, 02 engineering and technology, Condensed Matter - Soft Condensed Matter, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Crystallinity, 0103 physical sciences, Colloids, 010306 general physics, Porosity, Drying, Self-assembly, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Amorphous solid, Particle aggregation, Chemical engineering, Volume fraction, Soft Condensed Matter (cond-mat.soft), Particle size, 0210 nano-technology, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Abstract

International audience; The process of colloidal drying gives way to particle self-assembly in numerous elds including photonics or biotechnology. Yet, the mechanisms and conditions driving the nal particle arrangement in dry colloidal layers remain elusive. Here, we examine how the drying rate selects the nanostructure of thick dried layers in four dierent suspensions of silica nanospheres. Depending on particle size and dispersity, either an amorphous arrangement, a crystalline arrangement, or a rate-dependent amorphous-to-crystalline transition occurs at the drying surface. Amorphous arrangements are observed in the two most polydisperse suspensions while crystallinity occurs when dispersity is lower. Counter-intuitively in the latter case, a higher drying rate favors ordering of the particles. To complement these measurements and to take stock of the bulk properties of the layer, tests on the layer porosity were undertaken. For all suspensions studied herein, faster drying yields denser dry layers. Crystalline surface arrangement implies large bulk volume fraction (∼ 0.65) whereas amorphous arrangements can be observed in layers with either low (down to ∼ 0.53) or high (∼ 0.65) volume fraction. Lastly, we demonstrate via targeted additional experiments and SAXS measurements, that the packing structure of the layers is mainly driven by the formation of aggregates and their subsequent packing, and not by the competition between Brownian diusion and convection. This highlights that a second dimensionless ratio in addition to the Peclet number should be taken into account, namely the aggregation over evaporation timescale.

Published
2020
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8. Electrostriction, Electroresistance and Electromigration in Epitaxial BaTiO3 - based Heterostructures: Role of Interfaces and Electric Poling

Author

Antoine Barbier, D. Stanescu, Brice Sarpi, Thomas Aghavnian, Cindy L. Rountree, Jean-Baptiste Moussy, Hélène Magnan, Maxime Rioult, Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire Nano-Magnétisme et Oxydes (LNO), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), and Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX)

Subjects
Materials science, electric poling, 7. Clean energy, Electromigration, topography deformation, Condensed Matter::Materials Science, chemistry.chemical_compound, barium titanate, General Materials Science, ComputingMilieux_MISCELLANEOUS, memristor effect, Electrostriction, Spintronics, Ferroelectric materials, business.industry, Poling, Heterojunction, [CHIM.MATE]Chemical Sciences/Material chemistry, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Ferroelectricity, piezoresponse force microscopy PFM, Piezoresponse force microscopy, chemistry, Barium titanate, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Optoelectronics, Kelvin probe force microscopy KPFM, business, ferroelectric thin films
Abstract

Ferroelectric materials hold significant promise for potential applications in a number of fields including spintronics and solar energy harvesting. When integrating them into heterostructures, it ...

Published
2019
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9. Highly porous layers of silica nano-spheres sintered by drying: Scaling up of the elastic properties from the beads to the macroscopic mechanical properties

Author

Cindy L. Rountree, Daniel Bonamy, Arnaud Lesaine, Georges Gauthier, Véronique Lazarus, Fluides, automatique, systèmes thermiques (FAST), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la mécanique et Applications industrielles (IMSIA - UMR 9219), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), ANR-10-LABX-0032,LaSIPS,LABORATORY FOR SYSTEMS AND ENGINEERING OF PARIS SACLAY(2010), ANR-10-LABX-0039,PALM,Physics: Atoms, Light, Matter(2010), ANR-11-IDEX-0003,IPS,Idex Paris-Saclay(2011), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-EDF R&D (EDF R&D)

Subjects
Materials science, drying of colloidal dispersions, FOS: Physical sciences, PACS numbers: 82.70 Dd, 62.20.de, 81.16.Dn, 02 engineering and technology, Physics - Classical Physics, Condensed Matter - Soft Condensed Matter, mechanical properties, 01 natural sciences, Homogenization (chemistry), [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], 0103 physical sciences, Composite material, 010306 general physics, Porosity, Anisotropy, [PHYS]Physics [physics], Continuum mechanics, Multi-scale homogenization approaches, linear elasticity, Classical Physics (physics.class-ph), Fracture mechanics, General Chemistry, particles sintering, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Soft Condensed Matter (cond-mat.soft), 0210 nano-technology, Porous medium, Contact area, Rule of mixtures, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], highly interconnected porosity
Abstract

International audience; Layers obtained by drying a colloidal dispersion of silica spheres are found to be a good benchmark to test the elastic behaviour of porous media, in the challenging case of high porosities and nano-sized microstructures. Classically used for these systems, Kendall's approach explicitly considers the effect of surface adhesive forces onto the contact area between the particles. This approach provides the Young's modulus using a single adjustable parameter (the adhesion energy) but provides no further information on the tensorial nature and possible anisotropy of elasticity. On the other hand, homogenization approaches (e.g. rule of mixtures, and Eshelby, Mori-Tanaka and self-consistent schemes), based on continuum mechanics and asymptotic analysis, provide the stiffness tensor from the knowledge of the porosity and the elastic constants of the beads. Herein, the self-consistent scheme accurately predicts both bulk and shear moduli, with no adjustable parameter, provided the porosity is less than 35%, for layers composed of particles as small as 15 nm in diameter. Conversely, Kendall's approach is found to predict the Young's modulus over the full porosity range. Moreover, the adhesion energy in Kendall's model has to be adjusted to a value of the order of the fracture energy of the particle material. This suggests that sintering during drying leads to the formation of covalent siloxane bonds between the particles.

Published
2018
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10. Recent progress to understand stress corrosion cracking in sodium borosilicate glasses: linking the chemical composition to structural, physical and fracture properties

Author

Cindy L. Rountree, Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, This work has been supported by a number of funding agenciesincluding CEA, Triangle de la Physique (RTRA), Ile-de-France(C’Nano and ISC-PIF), National Science Foundation GraduateResearch program (Grant No. 0401467), ANR-10-LABX-0039,PALM,Physics: Atoms, Light, Matter(2010), and ANR-10-LABX-0032,LaSIPS,LABORATORY FOR SYSTEMS AND ENGINEERING OF PARIS SACLAY(2010)

Subjects
010302 applied physics, [PHYS]Physics [physics], Materials science, Acoustics and Ultrasonics, Borosilicate glass, Metallurgy, Oxide, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Corrosion, Stress (mechanics), chemistry.chemical_compound, Fracture toughness, chemistry, 0103 physical sciences, Fracture (geology), Stress corrosion cracking, 0210 nano-technology, Stress intensity factor
Abstract

This topical review is dedicated to understanding stress corrosion cracking in oxide glasses and specifically the SiO$_2$ B$_2$O$_3$ Na$_2$O (SBN) ternary glass systems. Many review papers already exist on the topic of stress corrosion cracking in complex oxide glasses or overly simplified glasses (pure silica). These papers look at how systematically controlling environmental factors (pH, temperature...) alter stress corrosion cracking, while maintaining the same type of glass sample. Many questions still exist, including: What sets the environmental limit? What sets the velocity versus stress intensity factor in the slow stress corrosion regime (Region I)? Can researchers optimize these two effects to enhance a glass’ resistance to failure? To help answer these questions, this review takes a different approach. It looks at how systemically controlling the glass’ chemical composition alters the structure and physical properties. These changes are then compared and contrasted to the fracture toughness and the stress corrosion cracking properties. By taking this holistic approach, researchers can begin to understand the controlling factors in stress corrosion cracking and how to optimize glasses via the initial chemical composition.

Published
2017
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12. Influence of Electronic Irradiation on Failure and Hardness Properties of Pure Silica Glasses

Author

Marina Barlet, Bruno Boizot, Cindy L. Rountree, J-M. Delaye, Richard Caraballo, Daniel Bonamy, M. Gennisson, Service de Physique et de Chimie des Surfaces et Interfaces (SPCSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Service d'Etudes du Comportement des Matériaux de Conditionnement (SECM), Laboratoire des Matériaux et Procédés Actifs (LMPA), Département de recherche sur les technologies pour l'enrichissement, le démantèlement et les déchets (DE2D), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Département de recherche sur les Procédés et Matériaux pour les Environnements complexes (DPME), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010302 applied physics, Oxide minerals, Materials science, Fracture mechanics, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, General Medicine, Crystal structure, 021001 nanoscience & nanotechnology, Microstructure, 01 natural sciences, Crystallographic defect, Indentation, 0103 physical sciences, Vickers hardness test, Irradiation, Composite material, 0210 nano-technology
Abstract

International audience; This paper’s focus is the failure and hardness properties of pure amorphous silica (Corning 7980) after β-irradiation at differentdoses (0-2 GGy). Crack propagation takes place in the SCC regime (10−7-10−10 m.s−1) and Vickers indentation techniques probethe hardness properties of the samples. Irradiation is found to create point defects which mainly include E’ centers, Non-BridgingOxygen Hole Centers and Peroxy Radicals. β-irradiation herein invokes minor changes in the structure. A small effect of β-irradiation on SCC and hardness variations cannot be eliminated, despite minute variations in the SCC and the hardness properties.

Published
2014
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13. Adsorbate Screening of Surface Charge of Microscopic Ferroelectric Domains in Sol–Gel PbZr$_{0.2}$ Ti$_{0.8}$ O$_3$ Thin Films

Author

O. Copie, Olivier Renault, Sara Gonzalez, Nicholas Barrett, Nicolas Chevalier, Claire Mathieu, D. Martinotti, Cindy L. Rountree, Gwenael Le Rhun, Institut Jean Lamour (IJL), Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude des NanoStructures et Imagerie de Surface (LENSIS), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX), Laboratoire d'Electronique et nanoPhotonique Organique (LEPO), The CEA Nanoscience program, IMPACT N4S, ANR-15-IDEX-0004,LUE,Isite LUE(2015), and Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, PZT, Analytical chemistry, 02 engineering and technology, Electron, PFM, 01 natural sciences, law.invention, PEEM, law, 0103 physical sciences, surface, General Materials Science, Surface charge, Thin film, 010306 general physics, Polarization (electrochemistry), Sol-gel, LEEM, [PHYS]Physics [physics], polarization, Condensed matter physics, screening, 021001 nanoscience & nanotechnology, Ferroelectricity, Curie temperature, Electron microscope, AFM, 0210 nano-technology
Abstract

International audience; We present a study of adsorbate screening of surface charge in microscopic ferroelectric domains in a sol−gel grown PbZr$_{0.2}$ Ti$_{0.8}$ O$_3$ thin film. Low-energy and photoemission electron microscopies were employed to characterize the temperature dependence of surface charge and polarization of ferroelectric domains written by atomic force microscopy. We study the role of charged adsorbates in screening of polarization-bound charges. We demonstrate that full-field electron microscopy is suitable for the determination of ferroelectric system properties such as the Curie temperature.

Published
2017
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14. Low energy electron imaging of domains and domain walls in magnesium-doped lithium niobate

Author

Claire Mathieu, Mael Guennou, Cindy L. Rountree, Guillaume F. Nataf, Patrick Grysan, D. Martinotti, Nicholas Barrett, Jens Kreisel, Laboratoire d'Etude des NanoStructures et Imagerie de Surface (LENSIS), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Materials Research and Technology (MRT) Department, Luxembourg Institute of Science and Technology (LIST), Physics and Materials Science Research Unit, University of Luxemburg, Laboratoire d'Electronique et nanoPhotonique Organique (LEPO), and Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX)

Subjects
[PHYS]Physics [physics], 010302 applied physics, Multidisciplinary, Materials science, Condensed matter physics, Band gap, Doping, Lithium niobate, Physics [G04] [Physical, chemical, mathematical & earth Sciences], 02 engineering and technology, Electron, 021001 nanoscience & nanotechnology, 01 natural sciences, Ferroelectricity, Article, law.invention, chemistry.chemical_compound, Low-energy electron microscopy, Physique [G04] [Physique, chimie, mathématiques & sciences de la terre], chemistry, law, Electric field, 0103 physical sciences, Electron microscope, 0210 nano-technology
Abstract

The understanding of domain structures, specifically domain walls, currently attracts a significant attention in the field of (multi)-ferroic materials. In this article, we analyze contrast formation in full field electron microscopy applied to domains and domain walls in the uniaxial ferroelectric lithium niobate, which presents a large 3.8 eV band gap and for which conductive domain walls have been reported. We show that the transition from Mirror Electron Microscopy (MEM – electrons reflected) to Low Energy Electron Microscopy (LEEM – electrons backscattered) gives rise to a robust contrast between domains with upwards (Pup) and downwards (Pdown) polarization, and provides a measure of the difference in surface potential between the domains. We demonstrate that out-of-focus conditions of imaging produce contrast inversion, due to image distortion induced by charged surfaces, and also carry information on the polarization direction in the domains. Finally, we show that the intensity profile at domain walls provides experimental evidence for a local stray, lateral electric field.

Published
2016
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15. Role of evaporation rate on the particle organization and crack patterns obtained by drying a colloidal layer

Author

Daniel Bonamy, Georges Gauthier, Véronique Lazarus, Keyvan Piroird, Cindy L. Rountree, Arnaud Lesaine, Fluides, automatique, systèmes thermiques (FAST), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Triangle de la Physique (RTRA), Ile-de-France (C'Nano and ISC-PIF) and Investissements d'Avenir of LabEx PALM (ANR-10-LABX-0039-PALM) and LabEx LaSIPS (ANR-10-LABX-0040-LaSIPS)

Subjects
Materials science, Solid structure, Cracks, Porous film, Evaporation rate, education, General Physics and Astronomy, FOS: Physical sciences, 02 engineering and technology, Condensed Matter - Soft Condensed Matter, 010402 general chemistry, 01 natural sciences, Colloid, Surface analysis via Atomic force microscopy (AFM), Colloids, Composite material, [PHYS.COND.CM-SM]Physics [physics]/Condensed Matter [cond-mat]/Statistical Mechanics [cond-mat.stat-mech], Nanoscopic scale, Condensed Matter - Statistical Mechanics, Statistical Mechanics (cond-mat.stat-mech), Self-assembly, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Particle, Soft Condensed Matter (cond-mat.soft), 0210 nano-technology, Layer (electronics), [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Abstract

International audience; – A scientific hurdle in manufacturing solid films by drying colloidal layers is preventing them from fracturing. This paper examines how the drying rate of colloidal liquids influences the particle packing at the nanoscale in correlation with the crack patterns observed at the macroscale. Increasing the drying rate results in more ordered, denser solid structures, and the dried samples have more cracks.Yet, introducing a holding period (at a prescribed point) during the drying protocol results in a more disordered solid structure with significantly less cracks. To interpret these observations, this paper conjectures that a longer drying protocol favors the formation of aggregates. It is further argued that the number and size of the aggregates increase as the drying rate decreases. This results in the formation of a more disordered, porous film from the viewpoint of the particle packing, and a more resistant film, i.e. less cracks, from the macroscale viewpoint.

Published
2016
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16. From network depolymerization to stress corrosion cracking in sodium-borosilicate glasses: Effect of the chemical composition

Author

Bruno Boizot, Richard Caraballo, Jean-Marc Delaye, Marina Barlet, Sylvain Peuget, Cindy L. Rountree, Daniel Bonamy, Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Service d'Etudes du Comportement des Matériaux de Conditionnement (SECM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), CEA, AREVA, Triangle de la Physique (RTRA) and Ile-de-France (C'Nano and ISC-PIF) have supported this research work., and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Chemical substance, Materials science, Sodium, Analytical chemistry, chemistry.chemical_element, Sodium borosilicate glass, 02 engineering and technology, 01 natural sciences, 0103 physical sciences, Materials Chemistry, Organic chemistry, Stress corrosion cracking, Boron, Chemical composition, 010302 applied physics, [PHYS]Physics [physics], Borosilicate glass, Depolymerization, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Fracture, chemistry, Chemical bond, Ceramics and Composites, 0210 nano-technology
Abstract

International audience; The study herein examines how chemical composition impacts sub-critical stress corrosion cracking (SCC) in sodium borosilicate glasses. The crack speed versus stress intensity factor (v vs. K$_I$) curves were obtained for seven ternary SiO$_2$-Na$_2$ O-B$_2$ O$_3$ (SBN) glasses of selected chemical compositions. Na$_2$O plays an interesting role in the SCC behavior. First, increasing the Na$_2$O concentration yields an increase in the environmental limit (K$_e$). Second, increasing the Na$_2$O concentration affects how fast SCC occurs as K$_I$ increases (i.e. the slope in region I SCC). This second effect is highly nonlinear: it is insignificant for Na$_2$O < 20% but it becomes increasingly important above 20%, when sodium acts as a network modifier. Raman spectroscopy and Molecular Dynamics (MD) simulations aid in revealing the structural variations which arise from increasing concentrations of Na$_2$O. Na$_2$O causes the relative proportions of the different chemical bonds accessible in SBN glasses to vary. For this series of glasses, the Si–O–Si bond does not dominate the SCC properties. SCC variations originate in the mesoscale structure where sodium ions act as network modifiers on both the silica and borate units, thus yielding a partial depolymerization (i.e. a decrease in the reticulation level) of the network. This second effect reveals itself to be the one responsible for the SCC chemical dependency. Poisson's ratio increases approximately linearly with increasing Na$_2$O concentration , and thus, it is also not simply proportional to the slope in region I SCC. Partial depolymerization of the glass provides a novel prospective on the controlling factors in the sub-critical crack growth.

Published
2016
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17. A unified study of crack propagation in amorphous silica: Using experiments and simulations

Author

Elisabeth Bouchaud, Cindy L. Rountree, C. Guillot, Daniel Bonamy, Rajiv K. Kalia, and S. Prades

Subjects
Materials science, Condensed matter physics, Mechanical Engineering, Metals and Alloys, Nucleation, Fracture mechanics, Fractography, Surface finish, Molecular dynamics, Brittleness, Mechanics of Materials, Cavitation, Materials Chemistry, Forensic engineering, Exponent
Abstract

Atomistic aspects of dynamic fracture in amorphous silica are investigated with molecular dynamics (MD) simulations. Simulations on amorphous silica were performed for two system sizes, 15 million and 113 million atoms. Crack propagation in these systems is accompanied by nucleation and growth of nanometer scale cavities up to 20 nm ahead of the crack tip. Cavities coalesce and merge with the advancing crack to cause mechanical failure. This scenario was also observed experimentally during stress corrosion ultra-slow fracture of glass using atomic force microscopy (F. Celarie et al., Phys. Rev. Lett. 90 (2003) 075504; S. Prades, D. Bonamy, D. Dalmas, E. Bouchaud, C. Guillot, Int. J. Sol. Struct. 42 (2004) 637). This mechanism has macroscopic consequences in terms of sample life-time and deformation field. The morphology of the fracture surfaces has also been studied by calculating the height–height correlation function. In general experiments reveal two universal roughness exponents, 0.5 for small length scales and 0.8 for large length scales. The MD simulations of the 15 million and 113 million atoms system find the first roughness exponent (0.5), but the second exponent (0.8) occurs over length scales inaccessible to MD simulations. Finally, the 113 million atoms simulation was used to map out the morphology and dynamics of the whole crack front.

Published
2007
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18. Local electronic structure and photoelectrochemical activity of partial chemically etched Ti-doped hematite

Author

Maxime Rioult, D. Stanescu, Rachid Belkhou, Cindy L. Rountree, Hélène Magnan, Stefan Stanescu, Antoine Barbier, Francesco Maccherozzi, Laboratoire Nano-Magnétisme et Oxydes (LNO), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), TASC - Laboratory TASC, INFM-CNR, Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX), and This work was funded by the CEA project DSM-Energie Hemaphoto and supported in part by Triangle de la Physique and Ile-de-France (C'Nano and ISC-PIF) under the IMAFMP grants.

Subjects
Materials science, Band gap, Inorganic chemistry, Oxide, 02 engineering and technology, 010402 general chemistry, 7. Clean energy, 01 natural sciences, chemistry.chemical_compound, Materials Chemistry, Absorption (electromagnetic radiation), [PHYS]Physics [physics], Surfaces and Interfaces, Hematite, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 0104 chemical sciences, Surfaces, Coatings and Films, Chemical energy, Chemical engineering, chemistry, visual_art, Photoelectrolysis, visual_art.visual_art_medium, Photocatalysis, Water splitting, 0210 nano-technology
Abstract

International audience; The direct conversion of solar light into chemical energy or fuel through photoelectrochemical water splitting is promising as a clean hydrogen production solution. Ti-doped hematite (Ti:α-Fe 2 O 3) is a potential key photoanode material, which despite its optimal band gap, excellent chemical stability, abundance, non-toxicity and low cost, still has to be improved. Here we give evidence of a drastic improvement of the water splitting performances of Ti-doped hematite photoanodes upon a HCl wet-etching. In addition to the topography investigation by atomic force microscopy, a detailed determination of the local electronic structure has been carried out in order to understand the phenomenon and to provide new insights in the understanding of solar water splitting. Using synchrotron radiation based spectromicroscopy (X-PEEM), we investigated the X-ray absorption spectral features at the L 3 Fe edge of the as grown surface and of the wet-etched surface on the very same sample thanks to patterning. We show that HCl wet etching leads to substantial surface modifications of the oxide layer including increased roughness and chemical reduction (presence of Fe 2+) without changing the band gap. We demonstrate that these changes are profitable and correlated to the drastic changes of the photocatalytic activity.

Published
2015
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19. Nanoscale damage during fracture in silica glass

Author

Cindy L. Rountree, Krishnaswa Ravi-Chandar, S. Prades, C. Guillot, Elisabeth Bouchaud, Davy Dalmas, Laurent Ponson, and Daniel Bonamy

Subjects
Coalescence (physics), Nanostructure, Materials science, Metallurgy, Computational Mechanics, Nucleation, Fracture mechanics, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Corrosion, Mechanics of Materials, Corrosion fatigue, Modeling and Simulation, Cavitation, 0103 physical sciences, Composite material, 010306 general physics, 0210 nano-technology, Nanoscopic scale
Abstract

We report here atomic force microscopy experiments designed to uncover the nature of failure mechanisms occuring within the process zone at the tip of a crack propagating into a silica glass specimen under stress corrosion. The crack propagates through the growth and coalescence of nanoscale damage spots. This cavitation process is shown to be the key mechanism responsible for damage spreading within the process zone. The possible origin of the nucleation of cavities, as well as the implications on the selection of both the cavity size at coalescence and the process zone extension are finally discussed.

Published
2006
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20. Multiresolution atomistic simulations of dynamic fracture in nanostructured ceramics and glasses

Author

Priya Vashishta, Cindy L. Rountree, Laurent Van Brutzel, Aiichiro Nakano, Shuji Ogata, and Rajiv K. Kalia

Subjects
Coalescence (physics), Materials science, Computational Mechanics, Dangling bond, Strained silicon, Amorphous solid, chemistry.chemical_compound, Fracture toughness, Silicon nitride, chemistry, Mechanics of Materials, Chemical physics, Modeling and Simulation, visual_art, visual_art.visual_art_medium, Ceramic, Stress intensity factor
Abstract

Multimillion atom molecular-dynamics (MD) simulations are performed to investigate dynamic frac- ture in glasses and nanostructured ceramics. Using multiresolution algorithms, simulations are carried out for up to 70 ps on massively parallel computers. MD results in amorphous silica (a-SiO2) reveal the formation of nanoscale cavities ahead of the crack tip. With an increase in applied strain, these cavities grow and coalesce and their coalescence with the advancing crack causes fracture in the system. Recent AFM studies of glasses confirm this behavior. The MD value for the critical stress intensity factor of a-SiO2 is in good agreement with experiments. Molecular dynamics simulations are also performed for nanostructured silicon nitride (n-Si3N4). Structural correlations in n-Si3N4 reveal that interfacial regions between nanoparticles are amorphous. Under an external strain, nanoscale cavities nucleate and grow in interfacial regions while the crack meanders through these regions. The fracture toughness of n-Si3N4 is found to be six times larger than that of crystalline α-Si3N4. We also investigate the morphology of fracture surfaces. MD results reveal that fracture surfaces of n-Si3N4 are characterized by roughness exponents 0.58 below and 0.84 above a certain crossover length, which is of the order of the size of Si3N4 nanoparticles. Experiments on a variety of materials reveal this behavior. The final set of simulations deals with the interaction of water with a crack in strained silicon. These simulations couple MD with a quantum-mechanical (QM) method based on the density functional theory (DFT) so that chemical processes are included. For stress intensity factor K = 0. 4M Pa m 1/2 , we find that a decomposed water molecule becomes attached to dangling bonds at the crack or forms a Si-O-Si structure. At K = 0. 5M Pa m 1/2 , water molecules

Published
2003
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21. Antiferromagnetic long-range spin ordering in Fe- andNiFe2-dopedBaTiO3multiferroic layers

Author

Cindy L. Rountree, Hélène Magnan, D. Stanescu, Cristian Mocuta, N. Jedrecy, T. Aghavnian, R. Belkhou, V. Badjeck, Antoine Barbier, and Philippe Ohresser

Subjects
Valence (chemistry), Materials science, Absorption spectroscopy, 02 engineering and technology, Crystal structure, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, Condensed Matter::Materials Science, Crystallography, Tetragonal crystal system, Ferromagnetism, 0103 physical sciences, X-ray crystallography, Antiferromagnetism, Multiferroics, 010306 general physics, 0210 nano-technology
Abstract

We report on the Fe doping and on the comparative Ni-Fe codoping with composition close to $\mathrm{NiF}{\mathrm{e}}_{2}$ of fully oxidized $\mathrm{BaTi}{\mathrm{O}}_{3}$ layers (\ensuremath{\sim}20 nm) elaborated by atomic oxygen plasma assisted molecular beam epitaxy; specifically any role of oxygen vacancies can be excluded in our films. Additionally to the classical in situ laboratory tools, the films were thoroughly characterized by synchrotron radiation x-ray diffraction and x-ray absorption spectroscopy. For purely Fe-doped layers, the native tetragonal perovskite structure evolves rapidly toward cubiclike up to 5% doping level above which the crystalline order disappears. On the contrary, low codoping levels $(\ensuremath{\sim}5%\mathrm{NiF}{\mathrm{e}}_{2})$ fairly improve the thin film crystalline structure and surface smoothness; high levels (\ensuremath{\sim}27%) lead to more crystallographically disordered films, although the tetragonal structure is preserved. Synchrotron radiation magnetic dichroic measurements reveal that metal clustering does not occur, that the Fe valence evolves from ${\mathrm{Fe}}^{2+}$ for low Fe doping levels to ${\mathrm{Fe}}^{3+}$ for high doping levels, and that the introduction of Ni favors the occurrence of the ${\mathrm{Fe}}^{2+}$ valence in the films. For the lower codoping levels it seems that ${\mathrm{Fe}}^{2+}$ substitutes ${\mathrm{Ba}}^{2+}$, whereas ${\mathrm{Ni}}^{2+}$ always substitutes ${\mathrm{Ti}}^{4+}$. Ferromagnetic long-range ordering can be excluded with great sensitivity in all samples as deduced from our x-ray magnetic absorption circular dichroic measurements. On the contrary, our linear dichroic x-ray absorption results support antiferromagnetic long-range ordering while piezoforce microscopy gives evidence of a robust ferroelectric long-range ordering showing that our films are excellent candidates for magnetic exchange coupled multiferroic applications.

Published
2015
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22. Hardness and toughness of sodium borosilicate glasses via Vickers's indentations

Author

Marina Barlet, Thibault Charpentier, Daniel Bonamy, Tanguy Rouxel, Jean-Marc Delaye, Cindy L. Rountree, Mickael Gennisson, Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Service de Physique et de Chimie des Surfaces et Interfaces (SPCSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Service d'Etudes du Comportement des Matériaux de Conditionnement (SECM), Laboratoire Structure et Dynamique par Résonance Magnétique (LCF) (LSDRM), Nanosciences et Innovation pour les Matériaux, la Biomédecine et l'Energie (ex SIS2M) (NIMBE UMR 3685), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Support by Triangle de la Physique (RTRA grant IMAFMP) and Ile-deFrance(C'Nano and ISC-PIF grant IMAFMP), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], Toughness, Materials science, Borosilicate glass, Fracture toughness, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Glass structure, Sodium borosilicate glasses, Residual stress, Hardness, Indentation, Materials Chemistry, Ceramics and Composites, Composite material, Deformation (engineering), Shear flow, Low sodium
Abstract

This study investigates the mechanical response of sodium borosilicate (SBN) glasses as a function of their chemical composition. Vickers's indentation tests provide an estimate of the material hardness ( H V ) and indentation fracture toughness ( K C VIF ) plus the amount of densification/shear flow processes. Sodium content significantly impacts the glass behavior under a sharp indenter. Low sodium glasses maintain high connected networks and low Poisson's ratios ( ν ). This entails significant densification processes during deformation. Conversely, glasses with high sodium content, i.e. large ν , partake in a more depolymerized network favoring deformation by shear flow. As a consequence, indentation patterns differ depending on the processes occurring. Densification processes appear to hinder the formation of half-penny median–radial cracks. Increasing ν favors shear flow and residual stresses enhance the development of half-penny median–radial cracks. Hence, K C VIF decreases linearly with ν .

Published
2015
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23. Atomistic Aspects of Crack Propagation in Brittle Materials: Multimillion Atom Molecular Dynamics Simulations

Author

Elefterios Lidorikis, Laurent Van Brutzel, Rajiv K. Kalia, Aiichiro Nakano, Priya Vashishta, and Cindy L. Rountree

Subjects
Nanocomposite, Materials science, Fracture mechanics, Surface finish, Amorphous solid, Molecular dynamics, Brittleness, Deflection (engineering), Chemical physics, visual_art, Forensic engineering, visual_art.visual_art_medium, General Materials Science, Ceramic
Abstract

▪ Abstract Atomistic aspects of dynamic fracture in a variety of brittle crystalline, amorphous, nanophase, and nanocomposite materials are reviewed. Molecular dynamics (MD) simulations, ranging from a million to 1.5 billion atoms, are performed on massively parallel computers using highly efficient multiresolution algorithms. These simulations shed new light on (a) branching, deflection, and arrest of cracks; (b) growth of nanoscale pores ahead of the crack and how pores coalesce with the crack to cause fracture; and (c) the influence of these mechanisms on the morphology of fracture surfaces. Recent advances in novel multiscale simulation schemes combining quantum mechanical, molecular dynamics, and finite-element approaches and the use of these hybrid approaches in the study of crack propagation are also discussed.

Published
2002
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24. Nominally brittle cracks in inhomogeneous solids: from microstructural disorder to continuum-level scale

Author

Cindy L. Rountree, Luc Barbier, Jonathan Barés, Marina Barlet, Daniel Bonamy, Systèmes Physiques Hors-équilibre, hYdrodynamique, éNergie et compleXes (SPHYNX), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and ANR-09-SYSC-0006,MEPHYSTAR,MEcanique et PHYsique STAtistique de la Rupture dans les matériaux fragiles hétérogènes(2009)

Subjects
Toughness, Materials science, Materials Science (miscellaneous), Biophysics, General Physics and Astronomy, Fracture and cracks, solid mechanics, Surface finish, crackling noise, interface structure, Physics::Geophysics, Condensed Matter::Materials Science, Crack closure, Brittleness, disordered systems, scaling laws, Physical and Theoretical Chemistry, Mathematical Physics, roughness, [PHYS]Physics [physics], Physics, Fracture mechanics, Mechanics, Avalanches, Microstructure, lcsh:QC1-999, fracture, crackling, fractals, Solid mechanics, Fracture (geology), lcsh:Physics
Abstract

International audience; We analyze the intermittent dynamics of cracks in heterogeneous brittle materials and the roughness of the resulting fracture surfaces by investigating theoretically and numerically crack propagation in an elastic solid of spatially-distributed toughness. The crack motion splits up into discrete jumps, avalanches, displaying scale-free statistical features characterized by universal exponents. Conversely, the ranges of scales are non-universal and the mean avalanche size and duration depend on the loading microstructure and specimen parameters according to scaling laws which are uncovered. The crack surfaces are found to be logarithmically rough. Their selection by the fracture parameters is formulated in term of scaling laws on the structure functions measured on one-dimensional roughness profiles taken parallel and perpendicular to the direction of crack growth.

Published
2014
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25. Roughness of Silica Glass Sub-Critical Fracture Surfaces

Author

Elisabeth Bouchaud, Frederic Lechenault, Matthieu George, Matteo Ciccotti, Gaël Pallares, and Cindy L. Rountree

Subjects
Root mean square, Materials science, Silica glass, Fracture (geology), Sub critical, Surface finish, Composite material, Stress intensity factor
Published
2012
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26. Evidence of deep water penetration in silica during stress corrosion fracture

Author

Jean-Philippe Bouchaud, Laurent Ponson, Cindy L. Rountree, Frederic Lechenault, E. Bouchaud, Fabrice Cousin, Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and California Institute of Technology (CALTECH)

Subjects
Heavy water, [PHYS]Physics [physics], Condensed Matter - Materials Science, Materials science, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Physics and Astronomy, Disordered Systems and Neural Networks (cond-mat.dis-nn), Penetration (firestop), Condensed Matter - Disordered Systems and Neural Networks, Reflectivity, Corrosion, Deep water, chemistry.chemical_compound, chemistry, Neutron, Neutron reflectometry, [NLIN]Nonlinear Sciences [physics], Composite material, Penetration depth
Abstract

We measure the thickness of the heavy water layer trapped under the stress corrosion fracture surface of silica using neutron reflectivity experiments. We show that the penetration depth is 65-85 \aa ngstr\"{o}ms, suggesting the presence of a damaged zone of $\approx$ 100 \aa ngstr\"{o}ms extending ahead of the crack tip during its propagation. This estimate of the size of the damaged zone is compatible with other recent results., Comment: 4 pages, 3 figures

Published
2010
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27. Plasticity-induced structural anisotropy of silica glass

Author

Damien Vandembroucq, Stéphane Roux, Mehdi Talamali, Elisabeth Bouchaud, Cindy L. Rountree, Service de Physique et de Chimie des Surfaces et Interfaces (SPCSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Physique et mécanique des milieux hétérogenes (UMR 7636) (PMMH), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), ANR-05-BLAN-0367,PLASTIGLASS,Modélisation multi-échelles et techniques micro-spectroscopiques pour l'étude de la plasticité des verres(2005), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
Materials science, amorphous, orientational order, General Physics and Astronomy, FOS: Physical sciences, 02 engineering and technology, anisotropy, Plasticity, 01 natural sciences, Molecular dynamics, 0103 physical sciences, Thermal, Tensor, Composite material, 010306 general physics, Anisotropy, glass, 021001 nanoscience & nanotechnology, Microstructure, fabric tensor, Amorphous solid, Condensed Matter - Other Condensed Matter, silica, plasticity, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0210 nano-technology, Ambient pressure, Other Condensed Matter (cond-mat.other)
Abstract

International audience; Amorphous silica density at ambient pressure is known to depend on thermal history (through the quenching rate) but also, at room temperature, on the maximum pressure applied in the past. Here we show that beyond density, a mechanical loading can endow the structure with an orientational order. Molecular dynamics simulations show evidence that amorphous silica develops a permanent anisotropic structure after extended shear plastic flow. This anisotropy which survives for an unstressed specimen is revealed markedly by the fabric tensor computed over the Si-O-Si orientations, albeit the SiO4 tetrahedra microstructure remains mostly unaltered.

Published
2009

28. Effects of finite probe size on self-affine roughness measurements

Author

Cindy L. Rountree, Gaël Pallares, Matteo Ciccotti, Frederic Lechenault, Elisabeth Bouchaud, Matthieu George, Laboratoire des colloïdes, verres et nanomatériaux (LCVN), Université Montpellier 2 - Sciences et Techniques (UM2)-Centre National de la Recherche Scientifique (CNRS), Service de Physique et de Chimie des Surfaces et Interfaces (SPCSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Service de physique de l'état condensé (SPEC - UMR3680), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
Length scale, General Physics and Astronomy, FOS: Physical sciences, 02 engineering and technology, Surface finish, 01 natural sciences, Optics, 0103 physical sciences, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 010306 general physics, Scaling, Condensed Matter - Statistical Mechanics, CRACK-PROPAGATION, ATOMIC-FORCE MICROSCOPY, Physics, Hurst exponent, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed matter physics, Statistical Mechanics (cond-mat.stat-mech), business.industry, Fracture mechanics, 021001 nanoscience & nanotechnology, Metrology, Universality (dynamical systems), FRACTURE SURFACES, SCALING PROPERTIES, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Affine transformation, 0210 nano-technology, business
Abstract

The roughness of fracture surfaces has been shown to exhibit self-affne scale invariance for a wide variety of materials and loading conditions. The range of scales over which this regime extends remains a matter of debate, together with the universality of the associated exponents. The topography of these surfaces is however often investigated with a contact probe that is larger than the micro-structure. In this case, we show that the correlation function of the roughness and the corresponding Hurst exponent $\zeta$ can only be measured down to a length scale $\Delta xc$ which depends on the probe size $R$, on $\zeta$ and on the surface topothesy $l$, and exhibit spurious behavior at smaller scales. First, we derive the dependence of $\Delta xc$ on these parameters from a simple scaling argument. Then we study this dependence numerically and verify our theoretical prediction. Finally, we establish the relevance of this analysis from AFM measurements on an experimental glass fracture surface and provide a metrological procedure for roughness measurements., Comment: 4 pages, 4 figures, submitted to PRL

Published
2009
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29. Dynamics of wing cracks and nanoscale damage in glass

Author

Cheng Zhang, Cindy L. Rountree, Zhen Lu, Rajiv K. Kalia, Ashish Sharma, Aiichiro Nakano, Priya Vashishta, Weiqiang Wang, Elisabeth Bouchaud, Ken-ichi Nomura, University of Southern California (USC), Service de Physique et de Chimie des Surfaces et Interfaces (SPCSI), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Coalescence (physics), [PHYS]Physics [physics], Wing, Materials science, Fissure, Wing crack, General Physics and Astronomy, Fracture mechanics, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, medicine.anatomical_structure, 0103 physical sciences, medicine, PACS numbers: 62.20.Mk, 31.15.Qg, 62.30.+d, Brittle solids, Dynamic range compression, Composite material, 010306 general physics, 0210 nano-technology, Nanoscopic scale
Abstract

International audience; We investigate initiation, growth, and healing of wing cracks in confined silica glass by molecular dynamics simulations. Under dynamic compression, frictional sliding of precrack surfaces nucleates nanovoids which evolve into nanocrack columns at the precrack tip. Nanocrack columns merge to form a wing crack, which grows via coalescence with nanovoids in the direction of maximum compression. Lateral confinement arrests the growth and partially heals the wing crack. Growth and arrest of the wing crack occur repeatedly, as observed in dynamic compression experiments on brittle solids under lateral confinement.

Published
2005
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30. High-end classical-quantum atomistic simulations of fracture

Author

Cindy L. Rountree, Aiichiro Nakano, Priya Vashishta, and Rajiv K. Kalia

Subjects
Software portability, Molecular dynamics, Grid computing, Computer science, Fracture (geology), Decomposition (computer science), Density functional theory, Grid, computer.software_genre, computer, Quantum, Computational science
Abstract

To achieve performance portability and adaptivity on DoD's high-end computing platforms as well as on a Grid of distributed computing resources, we are developing a virtualization-aware application framework based on data locality principles and a computational-space decomposition scheme. We have Grid-enabled multiscale materials simulations, which seamlessly integrate atomistic simulation based on the molecular dynamics (MD) method and quantum mechanical (QM) calculation based on the density functional theory. Multiscale MD/QM simulations are performed to study environmental effects of water molecules on fracture in silicon. Atomistic aspects of dynamic fracture in amorphous silica are investigated with MD simulations involving 113 million atoms.

Published
2004
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31. Damage of silicate glasses during stress corrosion

Author

F Lechenault, Cindy L. Rountree, Jean-Philippe Bouchaud, Elisabeth Bouchaud, Laurent Ponson, and Fabrice Cousin

Subjects
Stress (mechanics), History, Materials science, Metallurgy, Fracture (geology), Reflection (physics), Neutron, Silicate glass, Water content, Computer Science Applications, Education, Matrix (geology), Corrosion
Abstract

We show that water penetrates into the silicate glass matrix during stress corrosion fracture by probing what is stored under the fracture surface using neutron reflection. The concentration profile determined for two different values of the external loading exhibits a region close to the fracture surface where the water content is fairly elevated, suggesting a high amount of damage.

Published
2011
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32. Experimental investigation of damage and fracture in glassy materials at the nanometre scale

Author

Cindy L. Rountree, Daniel Bonamy, C. Guillot, Davy Dalmas, Laurent Ponson, S. Prades, and Elisabeth Bouchaud

Subjects
Coalescence (physics), Materials science, Mechanical Engineering, Nucleation, Fracture mechanics, Condensed Matter::Disordered Systems and Neural Networks, Industrial and Manufacturing Engineering, Physics::Geophysics, Stress (mechanics), Condensed Matter::Materials Science, Crack closure, Brittleness, Fracture toughness, Mechanics of Materials, Forensic engineering, Nanometre, Composite material, Safety, Risk, Reliability and Quality
Abstract

Slow crack advance is observed in real time via an Atomic Force Microscope in a minimal glass, amorphous Silica, under stress corrosion. Fracture proceeds through the nucleation, growth and coalescence of damage cavities, as recently reported in an aluminosilicate glass. The crack growth velocity as observed at the continuum scale is shown to be dominated by accelerating phases corresponding to the cavity coalescence with the main crack front. The process zone at the crack tip is then determined, and shown to increase with time when both the average crack growth velocity and the mechanical stress are kept constant. Transport of water molecules within the process zone is conjectured to be the dominant mechanism responsible for this time evolution. Migration of alkali Na ions in more complex Silicate glass is finally evidenced at the sub-mocrometric scale by observing through AFM the crack propagation in binary Na2O/SiO2 glasses.

Published
2006
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33. Dynamic fracture mechanisms in nanostructured and amorphous silica glasses million-atom molecular dynamics simulations

Author

Cindy L. Rountree, Priya Vashishta, Aiichiro Nakano, Rajiv K. Kalia, and Laurent Van Brutzel

Subjects
Molecular dynamics, Toughness, Materials science, Fracture toughness, Nanostructure, Cleavage (crystal), Fracture mechanics, Composite material, Amorphous solid, Intergranular fracture
Abstract

Parallel molecular dynamics simulations are performed to investigate dynamic fracture in bulk and nanostructured silica glasses at room temperature and 1000 K. In bulk silica the crack front develops multiple branches and nanoscale pores open up ahead of the crack tip. Pores coalesce and then they merge with the advancing crack-front to cause cleavage fracture. The calculated fracture toughness is in good agreement with experiments. In nanostrucutred silica the crack-front meanders along intercluster boundaries, merging with nanoscale pores in these regions to cause intergranular fracture. The failure strain in nanostructured silica is significantly larger than in the bulk systems.

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