It happened in the NBS laboratory in Maryland, USA, on a wintery day in 1982. Dr. Danny Shechtman raised his eyes from the penetrating electron microscope and said to himself: “there is no such animal.”
Shechtman, a young researcher in the Technion’s Faculty of Material Engineering, was invited to visit NBS by Dr. John Cahn who had visited the Technion in 1980. At that period Shechtman was involved in the production of metallic materials by rapid solidification. What he saw through his microscope on that day was a diffraction that indicated that the adhering crystal had a rotational symmetry of five – symmetry that up to that time had been considered impossible.
In 1912 the German scientist Von Laue discovered that most solids have a regular and periodic crystal structure. From then on until 1982 – for seventy years – no one recorded seeing crystals that were not periodic. It was under these circumstances that the paradigm that defines a crystal orderly and periodic and that periodic crystals can only have a rotational symmetry of 2, 3, or 4 and not 5 or 6 or any number larger than 6 was established. This was the basis for the theory of crystals (crystallography), which until the 1980s was a “closed science,” from which no one expected any revolutionary discoveries to emerge.
The surprised Shechtman went over and over his discovery and then went out to the hallway to share it with someone. But the corridor was empty. This was just the start of his isolation, isolation from the entire academic world.
Shechtman returned to the lab and continued to work and carried out a series of experiments in order to clarify what was causing the five-fold symmetry. In the beginning he thought that he was dealing with the phenomenon of “twins”. When he disproved this possibility, Shechtman understood that he had discovered new crystals and following this, he found this type of crystals in three different materials.
When Dr. Shechtman told his colleagues in the lab about his discovery, they replied with “there is no such thing.” But he did not give in, until the head of the NBS group of researchers told him: “Dr. Shechtman, you are embarrassing the group and I have to ask you to transfer to another research group.”
The young Dr. Shechtman moved to another group and thus finished his sabbatical. When he returned to the Technion he met Prof. Ilan Bloch who was the only one who believed in his discovery and even proposed a model explaining how this diffraction occurred. In the summer of 1984 Dr. Shechtman returned to Maryland and sent for publication, together with Prof. Bloch, a scientific paper that included an experimental section and a theoretical section but the paper was rejected.
The editors of the Journal of Applied Physics wrote: “The paper will not interest physicists. We recommend that you send it to a metallurgical journal.” The paper was indeed sent to a metallurgical journal – Metallurgical Transactions, which accepted it but announced that it would be a year before it was published. Shechtman showed that paper to his friend, John Cahn, who suggested sending another paper, an abridged version, to the journal Physical Review Letters. Four scientists participated in writing the abridged version – Shechtman, Bloch, Cahn and a French scientist, Dr. Danny Gratias. John’s suggestion turned out to be good one and the paper was published within a few weeks, in November 1984. Thus, a new scientific field was inaugurated: periodic quasicrystals.
The physics community went into an uproar and the community of chemists and mathematicians followed suit. The community of “believers” in Dr. Shechtman grew and grew but it ran up against the opposition of the conservative crystallography community, headed by Prof. Linus Pauling, the father of modern American chemistry and (twice) Nobel Prize laureate. “Shechtman is talking nonsense,” said Prof. Pauling at a scientific conference where Dr. Shechtman was sitting in the audience. “There are no such things as quasicrystals – there are only quasi-scientists.” Before he died, Pauling remained the only one who did not believe in Shechtman’s discovery. Dr. Shechtman became an associate professor at the Technion and within a year, a full professor. This was also an unheard of phenomenon and in his faculty they said with a smile, “it seems that rapid solidification also causes a rapid rise in the ranks.”
Today, Dist. Prof. Dan Shechtman is a Nobel Prize laureate, and winner of many prizes such as the Israel Prize, the Wolf Prize, the Emet Prize, and the Aminoff Prize of the Royal Swedish Academy of Sciences.
He is a member of the Israel Academy of Sciences and the American National Academy of Engineering.
Today, scientists are aware of hundreds of materials that have the structure Prof. Shechtman discovered and every year a number of national and international conferences are held on the subject.
Forty scientific books have been dedicated to periodic quasicrystals and many other books have had their chapter dealing with crystallography updated. Following the discovery and its corroboration, the International Union of Crystallography changed its fundamental definition of a crystal. In Israel, the material with the new structure was dubbed “Shechtmanite”.
Nevertheless, Prof. Shechtman, smiling and quiet, continues to work, developing new magnesium alloys and working on intermetallic compounds. He is not celebrating his success (and triumph) out in the public eye, just as he did not reveal his years of isolation in the academic world to many people.
The following are simple explanations of a few of the concepts appearing in this article:
Diffraction is a scattering of radiation as a result of interaction with material.
Rotation symmetry means, at its simplest level, if we rotate the object that we are talking about, we will again and again see the same picture; for example, if we very slowly turn a spinning top that has nothing written on its sides, we will see the same picture four times and then return to the starting point – this is four-fold symmetry. Prof. Shechtman’s discovery was the existence of five-fold symmetry.
Periodic crystals are characterized by being composed of a basic structural unit that repeats itself over and over, like the hexagonal units in honeycomb.