Directeur de Recherche (Research Director), CNRS
Institut Néel, CNRS, Grenoble, France
Abstract: Structural studies based on the powder diffraction technique are a prominent tool to understand the physical properties of materials in all fields of material science. I will present two examples of the use of powder diffraction at large experimental facilities in Grenoble, the ESRF synchrotron and the ILL neutron reactor, which allowed us to obtain a better understanding of complex physical phenomena. The first example will deal with the effect of high energy milling of organic compounds, studied by synchrotron x-ray powder diffraction in situ during milling. We examine the evolution of two different compounds for which high energy milling leads to amorphization or solid state transformation. The second example will show the complementarity of synchrotron and neutron powder diffraction in the study of doubly ordered perovskite compounds, to understand the appearance of hybrid improper ferroelectricity and the coupling between ferroelectric and magnetic orders. Synchrotron powder diffraction is used to unambiguously determine the symmetry and structures of these material which display a strong structural degeneracy from cubic perovskite. Neutron powder diffraction is used to get a more precise determination of the light atom positions and to investigate their magnetic ordering.
Biography: Prof. Pierre BORDET is the head of the « Materials – Radiation – Structure » research team at IN, vice-President of Association Française de Cristallographie and co-Editor of Acta Crystallographica, section B. He has published 232 publications in peer reviewed journals with citation 4821 times and h-factor of 35 (end of 2018). His main scientific interests include crystallography and crystal-chemistry, development of diffraction techniques and new methods for crystallography, PDF analysis of nano and ill-ordered materials, frustrated magnetism, superconductivity, ferroelectrics, multiferroics, etc.