Search results for: Sylvain Ravy

Items from 1 to 6 out of 6 results

article

Commissioning of a multi‐beamline femtoslicing facility at SOLEIL

Marie Labat, Jean-Blaise Brubach, Alessandra Ciavardini, Marie-Emmanuelle Couprie, more

Journal of Synchrotron Radiation > 25 > 2 > 385 - 398

The investigation of ultrafast dynamics, taking place on the few to sub‐picosecond time scale, is today a very active research area pursued in a variety of scientific domains. With the recent advent of X‐ray free‐electron lasers (XFELs), providing very intense X‐ray pulses of duration as short as a few femtoseconds, this research field has gained further momentum. As a consequence, the demand for...

chapter

High-Pressure X-Ray Absorption Spectroscopy: Application to the Local Aspects of Phase Transitions in Ferroelectric Perovskites

Jean-Paul Itie, Anne-Marie Flank, Pierre Lagarde, Sylvain Ravy, more

NATO Science for Peace and Security Series B: Physics and Biophysics > High-Pressure Crystallography > 51-67

X-ray absorption spectroscopy (XAS) provides information on the local order around a given atom. Under high pressure, this technique has been shown to be very sensitive to phase transitions. The evolution of the local structure of ferroelectric titanates under high pressure is obtained using XAS showing that the Ti atom remains out of the center of the surrounding oxygen octahedron just above the...

article

Homometry in the light of coherent beams

Sylvain Ravy

Acta Crystallographica Section A > 69 > 6 > 543 - 548

Two systems are homometric if they are indistinguishable by diffraction. A distinction is first made between Bragg and diffuse scattering homometry, and it is shown that in the last case coherent diffraction can allow the diffraction diagrams to be differentiated. The study of the Rudin–Shapiro sequence, homometric to random sequences, allows one to manipulate independently two‐point and four‐point...

article

In situ coherent X-ray diffraction of isolated core–shell nanowires

Sabine T. Haag, Marie-Ingrid Richard, Vincent Favre-Nicolin, Udo Welzel, more

Thin Solid Films > 2013 > 530 > Complete > 113-119

Anomalous coherent X-ray diffraction in Bragg geometry is a promising technique to study three-dimensional composition and strain fields in nanostructures. This paper presents results of coherent X-ray diffraction experiments on single Ag/Au core–shell nanowires with a typical diameter of 100 to 300nm in the as-prepared state and during in-situ heating. Experimental coherent diffraction patterns are...

article

High-pressure X-ray diffraction study of 1T-TaS2

Sylvain Ravy, Claire Laulhé, Jean-Paul Itié, Pierre Fertey, more

Physica B: Physics of Condensed Matter > 2012 > 407 > 11 > 1704-1706

We present a room temperature high-pressure X-ray diffraction study of the layered compound 1T-TaS ₂ up to 20GPa. This material is known to exhibit a variety of structural phase transitions that are ascribed to the stabilization of charge density wave states. It has been recently shown that at pressures larger than 3GPa and up to 25GPa, 1T-TaS ₂ becomes superconductor below about 5K...