Denis Gratias, associate director of the Microstructures Research Laboratory (LEM), is one of the pioneers in quasicrystals. He is in fact one of the co-authors of the publication that made Dan Shechtman’s discovery public (Nobel Prize winner for Chemistry 2011).
The Nobel Prize for Chemistry 2011 was awarded to Dan Shechtman (Technion Institute, Israel) for his discovery of quasicrystals in 1982. The publication that made this discovery public, proposing the description of a type of structure that was considered impossible at the time, dates back to 1984 and was written by D. Shetchman and three co-authors: Ilan Blech, then one of his colleagues at Technion; John Werner Cahn, professor, American NIST fellow and eminent specialist in thermodynamics applied to materials, and Denis Gratias, CNRS research director at the CECM (Vitry), a specialist in mathematical crystallography, invited to propose a mathematical model of this structure of crystals that were not really like any others.
John Werner Cahn, Dan Shechtman, Ilan Blech and Denis Gratias together at an international congress on quasicrystals (1995, Avignon, France)
©CNRS Photographic Collection - Pierre Grumberg
Since 1985 the laboratories of the Materials Division of ONERA have been interested in quasicrystals, which proved to be present in aluminium and lithium based alloys, made by the manufacturer Péchiney. It was also at this time that this manufacturer produced the first monocrystals with quasi-crystalline phase in these alloys. A very successful collaboration between ONERA and Denis Gratias ensued, developed on various quasi-crystalline materials.
In 1999, Denis Gratias joined the Microstructures Research Laboratory (LEM), a joint ONERA-CNRS laboratory that he started to direct in 2008 and of which he is currently the associate director. He is working there on the crystallographic modelling of quasicrystals, as well as the description of their very specific faults.
Atomic configurations observed in AlPdMn and AlCuFe quasicrystal alloy structures