Lecture


"Leonardo da Vinci" Award of the European Academy of Sciences

Jacques Friedel

by Prof. Didier Astruc


In recognition in his outstanding achievements in solid-state physics and physical metallurgy. A member of an illustrious family of famous French scientists spanning over six generations, he is one of the founders of materials science. His findings in dislocation theory, modeling of mechanical properties electronic structures of metals, especially the localized and delocalized states in diluted alloys, spin glasses, surface and cluster properties are unprecedented. He has considerably inspired and influenced several generations of solid-state physicists and was deeply involved in building a European school of condensed matter physics. He has been awarded the gold medal of the French CNRS (1970), elected as a foreign member of the National Academy of Sciences of the United States, and has served as the President of the French Academy of Sciences (1993-4).


Presentation of Professor Jacques Friedel

by Prof. Yves Bréchet

Materials science and physical metallurgy are a relatively new Science, at least in their current form. Although this science relies on centuries of practice, and a huge accumulated database of empirical knowledge, the detailed understanding of the underlying principles, the development of reliable concepts to understand the mechanical properties of matter and the relation between the deep quantum mechanics basis and the macroscopic behaviour of metals, have emerged only in the last century. This was made possible by the development of solid-state physics as one of the most prolific outcomes of quantum physics and statistical physics. Jacques Friedel has been a major actor both in the creation of solid-state physics, and in the development of materials science and physical metallurgy in its modern form.

Jacques Friedel was born into a family where science and engineering was part of the educational tradition. The tradition started by his great-grand father Charles Friedel, a famous organic chemist and crystallographer at Paris Sorbonne, his grand-father Georges Friedel best known for his work on liquid crystals, his father Edmond Friedel who was the director of the National School of Mines (1937-65), and his cousin Charles Crussard with whom his made his first steps in research. His studies followed the “Voie Royale” in the French system: he entered the Ecole polytechnique (1944-46) then the Ecole nationale supérieure des Mines (1946-48), as a member of the “Corps des Mines”, the highest order of technical civil servants in France. He then decided on a career in science. He obtained a Licence ès sciences degree at the University of Paris in 1948 and was then initiated into physical metallurgy in the Metallurgy Laboratory of the School of Mines headed by C. Crussard.

He spent three years at Bristol University (UK) in Nevill F. Mott’s physics department where he became acquainted with the electronic structure of metals and with crystal defects including dislocations, topics that were to become his favourite research fields. In 1952 he obtained his PhD from Bristol and a Doctorat d’Etat in Paris in 1954 on the electronic structure of impurities in metals. He became assistant professor at Paris University, then full professor of Solid-State Physics at Paris Sud-University in Orsay from 1959 to 1989. For thirty years he developed with André Guinier and Raymond Castaing a research school in solid-state physics, and has been extremely influential in shaping the field of condensed matter physics in France. Many of the famous names in the field, including Nobel prize winners P. G. De Gennes and A.Fert, and P. Nozieres, passed through his lab and started here their distinguished careers. Thus J. Friedel can be seen as the “grand father” of condensed matter physics and physical metallurgy in France.

The exercise of exploring Jacques Friedel’s career and great achievements sheds an interesting light on the birth of modern materials science. He has written one of the classic references for metallurgists: “Dislocations”, which together with the related book by A. H. Cottrell, remains the bible for the physical understanding of plastic behaviour of metals and alloys.  He pioneered the application of solid-state physics to the theory of alloys, in particular the electronic structures of solid solutions and the charge distribution around impurities (the famous “Friedel’s oscillations”). A number of standard approaches in physical metallurgy bear his name: for precipitation hardening (Friedel’s statistics), for work hardening by dislocations (Friedel Cross slip theory, Friedel-Saada forest hardening). His works on clusters and other low dimensional systems in connection with organic and high-Tc superconductivity or on liquid crystal are also seminal. The major contributions of Friedel to the physical aspects of the electronic structure of metals and alloys, and the physical understanding of plasticity, have inspired several generations of researchers and are linked to very important practical discoveries and advances in practical engineering materials.

His contributions in material science and metallurgy reflect a time (from the 50’s to the 70’s) when these fields were being built, and that were the equivalent of the “magic decades” of quantum physics. The memoirs of Jacques Friedel “Graine de Mandarin” gives a vivid description of the evolution of ideas in Bristol at the time of Nevill Mott, Charles Franck, and Frank Nabarro: it was an intellectually fruitful time when a group of extremely creative scientists produced in a few years most of the concepts that are now operative in materials science.

He has also developed a style of modelling in physical metallurgy, a direct heritage of Mott’s influence, which is unrivalled: the art of simplifying very complex problems into their key features and to propose simple, elegant analytical solutions of these simplified situations, which happen to be the most powerful guidance when more complex models or computer simulations become necessary.  The tight binding model for the cohesion of transition metals due to Friedel is a magnificent illustration of this “style” which can both be taught at the undergraduate level, and still be extremely useful for today’s research.

Jacques Friedel has been extremely influential in the development of the broad fields of the electronic structure of metals and alloys and of physical metallurgy in France, where he has been for decades the head of a school in solid-state physics and metallurgy. He has also been very influential throughout Europe and the US through the extensive network he had built at a time where it was not fashionable to do so. In any place of the world where physical metallurgy is developed, the name of Jacques Friedel is known.

His commitment to the development of science in France and in Europe is visible in the various official positions he has held: Jacques Friedel chaired the Consultative Committee to the French Government for scientific and technological research (1978-1980), he was the President of the Société française de physique and of the European Physical Society. Among many responsibilities in French scientific institutions, Jacques Friedel became the vice president and then the President of the French Academy of Sciences (1990-1994).

Jacques Friedel, in spite of his numerous commitments in scientific policy, has never stopped doing science and discussing the most recent developments in the various aspects he has pioneered. He has always been accessible to open and friendly discussions both with students and with colleagues. His advice is highly valued by the community, and many of the younger researchers in the field have been surprised to find in their letter box one of these carefully handwritten letters from someone they consider as their master, asking very accurate questions on their most recent work. The influence of Jacques Friedel in physical metallurgy is a lasting presence, well after he has retired. Not influenced by current fads of fashions in condensed matter physics, his contributions reflect his deep insight into the truly fundamental problems, and also a much appreciated open-mindedness: not only his ability to give advice, but also to listen carefully and very eagerly to new ideas, new results and new methods. His contribution to the intellectual development of the best young minds in France, in successive generations, will be a lasting legacy.

His international recognition is reflected in the many honours he has received in his career and the numerous academies that have elected him as a fellow: Grand Prix de la société Francaise de Metallurgie,  Holweck Prize, Medaille d’or du CNRS, Von Hippel award (US), member of French Académie des sciences, French Académie des Technologies, Foreign member of  the Royal Society (UK), Foreign member of American Academy of Arts and Sciences, Fellow of the American Physical Society, Fellow of the Institute of Physics, Foreign member of the Max Planck Gesellshaft, Foreign member of the National Academy of Sciences Foreign Associate (US), Member of the Royal Swedish Academy of Science, Member of Academia Leopoldina, Member of the Science Academy of Brazil, Member of the Science Academy of Belgium, Honorary fellow of the European Physical Society. He holds Honorary Doctorate degrees from Bristol, Cambridge, Geneve, Zagreb and Ecole Polytechnique Federale de Lausanne.

In giving the Leonardo Da Vinci medal to Jacques Friedel, the European Academy of Sciences recognizes one of the founding fathers of a field which sits at the border between mechanics, physics and chemistry, and which is both fundamental science and engineering. Jacques Friedel has contributed richly to the field, not only by creating a school that had many connections all over Europe and the world, but he has given to the discipline an art of elegant simplification on which it can rely for its present and future development.

 

Yves Bréchet