Denis Gratias, born on 22 September 1947 in Paris (France) is a French scientist, emeritus research director at the CNRS. His speciality is materials science, in particular crystallography. Since the discovery of quasicrystals by Dan Shechtman in 1982, he has contributed to their description, notably by developing theoretical models. He is a correspondent member at the French Academy of Sciences since 1994. [1]
Denis Gratias graduated as a chemical engineer in 1970 at Chimie ParisTech. In 1978, Denis Gratias defended his PhD thesis at the Structural Metallurgy Laboratory (CNRS-ENSCP), entitled Cristallography of interfaces in homogeneous crystals [2] and developed with Richard Portier a formalism of fast electron diffraction. [3] He then completed his post-doctoral training at the University of California at Berkeley (USA) where he was interested in the problems of statistical thermodynamics of generalized mean field [4] (Cluster Variation Method).
Back in France, he took up his position at the Centre d'Études de Chimie Métallurgique (CECM), CNRS laboratory in Vitry-sur-Seine (France), but was soon invited by John-Werner Cahn to the Institute of Theoretical Physics at the University of California at Santa Barbara (USA) to participate in an interdisciplinary collaboration on theoretical physics and materials science. It was on this occasion that he was confronted with the unresolved problem of the 5th-order diffraction observed in April 1982 by Dan Shechtman. He contributed to the seminal paper [5] of 1984 announcing the discovery of quasicrystals.
Upon his return, a long period of intense collaboration on crystallography began between the CECM at Vitry and the Centre de physique théorique (CPHT) of the École Polytechnique.
In 2000, Denis Gratias and his wife Marianne Quiquandon moved to Châtillon to the Laboratoire d'étude des microstructures (LEM [archive], a joint ONERA-CNRS laboratory), which he directed until 2009.
Since 2014, he has been CNRS Emeritus Research Director assigned to Chimie ParisTech, at the Institut de Recherche de Chimie Paris (IRCP), within the structural metallurgy team.
A quasiperiodic crystal, or quasicrystal, is a structure that is ordered but not periodic. A quasicrystalline pattern can continuously fill all available space, but it lacks translational symmetry. While crystals, according to the classical crystallographic restriction theorem, can possess only two-, three-, four-, and six-fold rotational symmetries, the Bragg diffraction pattern of quasicrystals shows sharp peaks with other symmetry orders—for instance, five-fold.
The École Polytechnique is one of the 204 French engineering schools accredited as of 1st September 2020 to award an diplôme d'ingénieur. It is one of the most prestigious and selective grandes écoles in France. It is also along with l'École spéciale militaire de Saint-Cyr, l'École de l'air, l'ENSTA Bretagne, l'École des officiers de la Gendarmerie nationale, l'École navale and l'École de santé des armées — one of the seven major French military schools. It is a French public institution of higher education and research in Palaiseau, a suburb south of Paris. The school is a constituent member of the Polytechnic Institute of Paris.
ESPCI Paris is a prestigious grande école founded in 1882 by the city of Paris, France. It educates undergraduate and graduate students in physics, chemistry and biology and conducts high-level research in those fields. It is ranked as the first French École d'Ingénieurs in the 2017 Shanghai Ranking.
John Werner Cahn was an American scientist and recipient of the 1998 National Medal of Science. Born in Cologne, Weimar Germany, he was a professor in the department of metallurgy at the Massachusetts Institute of Technology (MIT) from 1964 to 1978. From 1977, he held a position at the National Institute of Standards and Technology. Cahn had a profound influence on the course of materials research during his career. One of the foremost authorities on thermodynamics, Cahn applied the basic laws of thermodynamics to describe and predict a wide range of physical phenomena.
Dan Shechtman is the Philip Tobias Professor of Materials Science at the Technion – Israel Institute of Technology, an Associate of the US Department of Energy's Ames Laboratory, and Professor of Materials Science at Iowa State University. On April 8, 1982, while on sabbatical at the U.S. National Bureau of Standards in Washington, D.C., Shechtman discovered the icosahedral phase, which opened the new field of quasiperiodic crystals.
Chimie ParisTech, founded in 1896 within the University of Paris, is an engineering school and a constituent college of PSL Research University specialised in chemical science. It is located in the 5th arrondissement of Paris.
The Institut des molécules et de la matière condensée de Lille - IMMCL Chevreul is a physics and chemistry research institute. It is a member of the University of Lille.
Ludwik Leibler, born in 1952 is a Polish-born French physicist. He is Professor of École supérieure de physique et de chimie industrielles de la ville de Paris and member of the French Academy of Sciences and National Academy of Engineering.
Jacques Friedel ForMemRS was a French physicist and material scientist.
Peter Kramer is a German physicist.
Alan Lindsay Mackay FRS is a British crystallographer, born in Wolverhampton.
Antoine Georges is a French physicist. He is a professor at the Collège de France in Paris and the director of the Center for Computational Quantum Physics at the Flatiron Institute, New York.
The Laboratoire de Physique des Solides is a research institute of the Paris-Saclay University, associated to the National Center of Scientific Research (CNRS) as a joint research unit. It is located in Orsay, France, about 25 km southwest of Paris.
Maurice Kleman was a French physicist involved in experimental and theoretical studies of the physics of defects; he has covered various fields of research, from condensed matter to heliophysics. As an author, he has been collected by libraries worldwide.
Lenka Zdeborová is a Czech physicist and computer scientist who applies methods from statistical physics to machine learning and constraint satisfaction problems. She is a professor of physics and computer science and communication systems at EPFL.
Philippe Sautet is a French chemist. He was elected to the French Academy of sciences on 30 November 2010. He was a research director at the CNRS and works in the chemistry laboratory of the École normale supérieure de Lyon where he devoted a large part of his scientific activity to molecular modelling. Now he is a professor at the University of California - Los Angeles.
Claude Bouchiat, born 16 May 1932, is a French physicist, member of the French Academy of sciences.
This is a timeline of crystallography.
Christian Alfred Elie Janot was a French physicist and materials scientist known for his work on materials characterization using Mössbauer spectroscopy and his physical metallurgy studies of quasicrystals and noncrystalline materials using neutron scattering techniques.
Marianne Cornier-Quiquandon is a French metallurgist for the French National Centre for Scientific Research (CNRS), and a member of the structural metallurgy team in the Institut de Recherche de Chimie Paris (IRCP), a joint research institute of CNRS and Chimie ParisTech. Her research involves the study of quasicrystals in aluminum alloys, with her husband Denis Gratias.
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