Publications associées à Compacité (cristallographie)

Theory of screw dislocation strengthening in random BCC alloys from dilute to "High-Entropy" alloys

Random body-centered-cubic (BCC) "High Entropy" alloys are a new class of alloys, some having high strength and good ductility at room temperature and some having exceptional high-temperature strength. There are no theories of strengthening of screw disloc ...

PERGAMON-ELSEVIER SCIENCE LTD2020

Mechanistic origin of high strength in refractory BCC high entropy alloys up to 1900K

William Curtin, Francesco Maresca

The body centered cubic (BCC) high entropy alloys (HEAs) MoNbTaW and MoNbTaVW show exceptional strength retention up to 1900K. The mechanistic origin of the retained strength is unknown yet is crucial for finding the best alloys across the immense space of ...

PERGAMON-ELSEVIER SCIENCE LTD2020

In Situ Deformation Studies of HCP Metal Alloys with Neutron Diffraction, X-Ray Diffraction, and High Resolution Digital Image Correlation

Karl Alan Sofinowski

Mg and Ti alloys are attractive materials for structural applications in the transportation and biomedical industries due to their high strength-to-weight ratios. However, due to their hexagonally close-packed (HCP) lattice structure, they exhibit poor for ...

EPFL2019

New refinement of the crystal structure of Zn(NH3)(2)Cl-2 at 100 K

Arnaud Magrez, Trpimir Ivsic

The crystal structure of [ZnCl2(NH3)(2)], diamminedichloridozinc, was reinvestigated at low temperature, revealing the positions of the hydrogen atoms and thus a deeper insight into the hydrogen-bonding scheme in the crystal packing. In comparison with pre ...

2019

Comprehensive first-principles study of stable stacking faults in hcp metals

William Curtin, Binglun Yin, Zhaoxuan Wu

The plastic deformation in hcp metals is complex, with the associated dislocation core structures and properties not well understood on many slip planes in most hcp metals. A first step in establishing the dislocation properties is to examine the stable st ...

Elsevier2017

Hard-sphere displacive model of deformation twinning in hexagonal close-packed metals. Revisiting the case of the (56, a) contraction twins in magnesium

Cyril Cayron

Contraction twinning in magnesium alloys leads to new grains that are misoriented from the parent grain by a rotation (56°, a). The classical shear theory of deformation twinning does not specify the atomic displacements and does not explain why contractio ...

Int Union Crystallography2017

Scaling for hard-sphere colloidal glasses near jamming

Eric DeGiuli

Hard-sphere colloids are model systems in which to study the glass transition and universal properties of amorphous solids. Using covariance matrix analysis to determine the vibrational modes, we experimentally measure here the scaling behavior of the dens ...

IOP Publishing - EPL Association2016

Mechanism and energetics of < c plus a > dislocation cross-slip in hcp metals

William Curtin, Zhaoxuan Wu

Hexagonal close-packed (hcp) metals such as Mg, Ti, and Zr are lightweight and/or durable metals with critical structural applications in the automotive (Mg), aerospace (Ti), and nuclear (Zr) industries. The hcp structure, however, brings significant compl ...

National Academy of Sciences2016

A new strain rate dependent continuum framework for Mg alloys

Magnesium (Mg) alloys have recently been put under the spotlight for their specific strength, the highest among structural metals. Although the mechanical behaviour of Mg alloys at quasi-static strain rates has been extensively modelled in the recent years ...

Elsevier Science Bv2016

Angular distortive matrices of phase transitions in the fcc-bcc-hcp system

Cyril Cayron

This work generalizes the one-step model previously developed on fcc-bcc martensitic transformations to the larger family of phase transitions in the fcc-bcc-hcp system. The angular distortive matrices are calculated for the bcc-fcc, bcc-hcp and fcc-hcp tr ...

Elsevier2016

Hg(II) coordination complexes containing the tris(2-pyridylmethyl) amine ligand: Synthesis, characterization and crystal structure analysis

Kurt Schenk, Farzaneh Fadaei Tirani

Two new Hg(II) coordination compounds containing the tris(2-pyridylmethyl)amine (TPA) ligand were synthesized by conventional and sonochemical methods, characterized by spectroscopic techniques (FT-IR and elemental analysis) and their X-ray crystallographi ...

Elsevier2016

Energetics of dislocation transformations in hcp metals

William Curtin, Binglun Yin, Zhaoxuan Wu

Dislocation core structures of hcp metals are highly complex and differ significantly among the hcp family. Some dislocations undergo unconventional transformations that have significant effects on the material plastic flow. Here, the energetics of disloca ...

Elsevier2016

Total Syntheses of (−)-Mersicarpine, (−)-Scholarisine G, (+)-Melodinine E, (−)-Leuconoxine, (−)-Leuconolam, (−)-Leuconodine A, (+)-Leuconodine F, and (−)-Leuconodine C: Self-Induced Diastereomeric Anisochronism (SIDA) Phenomenon for Scholarisine G and Leuconodines A and C

Qian Wang, Jieping Zhu, Zhengren Xu

Enantioselective total syntheses of title natural products from a common cyclohexenone derivative (S)-18 were reported. Ozonolysis of (S)-18 afforded a stable diketo ester (R)-17 that was subsequently converted to two skeletally different natural products, ...

Amer Chemical Soc2015

Strength and texture of Pt compressed to 63 GPa

Susannah McGregor Dorfman

Angle-and energy-dispersive X-ray diffraction experiments in a radial geometry were performed in the diamond anvil cell on polycrystalline platinum samples at pressures up to 63 GPa. Observed yield strength and texture depend on grain size. For samples wit ...

Amer Inst Physics2015

Structure Sensitivity of 2-Methyl-3-butyn-2-ol Hydrogenation on Pd: Computational and Experimental Modeling

Lioubov Kiwi, Rocio Micaela Crespo Quesada

In the frame of DFT paradigms, the adsorption of 2-methyl-3-butyn-2-ol (MBY) and 2-methyl-3-buten-2-ol (MBE) on a Pd-30 cluster, including both {100} and {111} faces, was studied along with the pathways involved in the hydrogenation, taking place on plane ...

American Chemical Society2014

Development of X-Ray Powder Diffraction Methods for Biomolecules

Sebastian Basso

The comparable order of magnitude between interatomic distances in a crystal and the wavelength of X-rays make X-ray crystallography the ideal analytical tool to gain insight into the structure of crystalline material, including biomolecules. Nevertheless, ...

EPFL2011

Modified herringbone reconstruction on Au(111) induced by self-assembled Azure A islands

Wolf-Dieter Schneider, François Patthey, Frédéric Rossel

Upon submonolayer deposition of Azure A molecules onto reconstructed Au(1 1 1), two-dimensional quasi-rectangular islands are observed by low-temperature scanning tunneling microscopy. Strikingly, the 22 x root 3 reconstruction with alternating hexagonal c ...

2008

Lifetime of the Cs6P(1/2) state in bcc and hcp solid He-4

Simone Ulzega

We present the first experimental study of time-resolved fluorescence from laser-excited Cs(6P(1/2)) atoms isolated in a solid He-4 matrix. The results are compared to the predictions of the bubble model including the interaction of the atomic dipole with ...

2008

Domain structure and optical properties of colloidal photonic crystal

Heinrich Hofmann

Thin colloidal photonic crystals were grown using shear-flow crystallization of polystyrene colloidal nanoparticles. The arrays consist of two types of domains, which are clearly visible on scanning electron microscopy patterns. Both domains have cubic clo ...

2006

Arrested phase separation in a short-ranged attractive colloidal system: A numerical study

Giuseppe Foffi, Francesco Sciortino

We numerically investigate the competition between phase separation and dynamical arrest in a colloidal system interacting via a short-ranged attractive potential. Equilibrium fluid configurations are quenched at two different temperatures below the critic ...

2005