Interview with the 2011 Nobel Laureate in Chemistry Dan Shechtman, 6 December 2011. The interviewer is Adam Smith, Editorial Director of Nobel Media.

Daniel Shechtman, welcome to Stockholm.

Dan Shechtman: Thank you.

You are here to receive the Nobel Prize in Chemistry for your discovery of quasicrystals. It seems to me that there is a parallel to your discovery and that made by Wilhelm Röntgen, who received the very first Nobel Prize in Physics in 1901. In both cases there was an observation which many people, the majority of people would have just ignored. But that you, and in Röntgen’s case he, had the tenacity to take seriously. You saw the electron diffraction pattern and you didn’t let it go, you stuck with it.

Dan Shechtman: That is corrects. I know of course about the Röntgen story, I read about him and today I showed my family – in the museum – the exhibition they have about him. An excellent discovery of course. Let’s talk about Röntgen for a minute. A year after Röntgen made the discovery in 1895, x-rays were already used for medical purposes but only until von Laue, in 1912, did his famous experiment, did people know what it was really about. They knew that there was some radiation but they did not know what it was. So it took quite a few years, 17 years, between discovery and a real understanding of what it was. Both Röntgen – the great – and myself, we stumbled upon the discovery, it just happened, we saw it, but we made the observation and didn’t let go. We investigated it more and more. But not only Röntgen, many other discoveries that received the Nobel Prize – people just happens to see them and say Hm, that’s interesting, and continue to work. My case is just one of them.

Yes. It’s the case of that Pasteur thing of chance favouring the prepared mind, people knowing enough to take things seriously.

Dan Shechtman: Yes.

To know what to pay attention to. Here, in these /- – -/ surroundings, is a very far cry from you in your office in the National Institute of Standards and Technology in 1982 with this picture in front of you which you were taking seriously but everybody else were saying, Ignore it, Danny.

Dan Shechtman: Not everybody, I will tell you what was the span of reactions. Shall I? Okey, good. Let’s talk about the good people – the good side – my host for instance, John Cahn. He said to me, Danny, this is trying to tell us something and I challenge you to find out what it is. This was the good reaction. Bad reaction: my group leader came to my office one day – this was in the first month that I was talking about, this material – smiling /- – -/ he put an x-ray diffraction book on my desk and said something like, Danny, please read this book so that you understand that what you are saying can not be.

And this is because this picture you had seemed to defy the possibilities that were allowed under crystallography in those days?

Dan Shechtman: That is correct. But it was not one picture, it was a long series of experiments. The famous diffraction picture is one of very many experiments, all done by electron microscopy, transmission electron microscopy. So, he gave me the book and said, Please read. I said, I know this book, I am a teacher at the Technion I teach these things and I don’t need to read it. I am telling you this is something different, it’s not in the book. He took the book and sometime later – now I don’t remember how many days or how many hours it was – but he came back and said, Danny, you are a disgrace to my group and I want you to leave my group, I don’t want to be associated with this. So he moved to another group. This didn’t mean much, it sounds traumatic but it was not, I just had to find another group leader who would to adopt me – the orphan, the scientific orphan – and somebody did. The only amendment was instead of reporting to this secretary I reported to that secretary. I didn’t move from my office or from my laboratory, it was just about the same, so it was not very traumatic – now when people hear about it, Wow, thrown away from your group! Yes, but it was, not for me at least, it was not traumatic. It was not nice, I didn’t feel very good about it, but … This was a span of reactions between encouragement and rejection – and everything was somewhere in between.

But it takes a particular sort of person to stick to their guns even though they don’t know what they are looking at, they don’t know what the explanation is for this. You seem to have found something new but at the same time you haven’t got a clue presumably, at that point, of what might be causing it.

Dan Shechtman: The is correct but they knew what it was not. I knew that it was not twins – I will explain. In a periodic crystal there are different defects including grain boundaries of crystal boundaries. Imagine that this is a group of atomic plain and here is another crystal and sometimes they match in a certain way which is very peculiar, very precise the way they match. This is called a twin boundary. If you take five of them and take a diffraction of all of them together, then there is a five-fold symmetry. But it is a pseudo five-fold symmetry, because it is not taken from one crystal, it is taken from five crystals. These are called twin boundaries and the crystals are called twins, because they look like twins. I was looking for the twins. In the first minutes of the observation I was looking for the twins and performed the serial experiments and you can see that on my log book page which became famous – it was meant for me to read only but by now everybody saw that page – you could see this serial of experiments on that page and in day one I knew that it was not twins, but I didn’t know what it was. That took some time.

It’s having the confidence in your craft it’s knowing that you know enough about the experiment to trust what you have done, and that doesn’t come easily, it takes time.

Dan Shechtman: My tool was, my main tool still is an electron microscope, a transmission electron microscope. A transmission electron microscope is a very powerful tool to investigate structure of matter. Because the resolution of /- – -/ microscopes is very high you can actually see atoms – and you could see atoms 30 years ago also – now we have better resolutions, but you could see them. You could get a lot of information about not only the structure of the material but about the chemical composition. You can really investigate deep into the structure and understand what’s going on within it. This is something that you cannot do with x-rays unless you have large enough crystals. Our crystals were about two microns each, too small to get a single crystal x-ray diffraction but large enough to get a single crystal electron diffraction. If you have many many tiny crystals – like that – and you take an x-ray diffraction you lose the rotational symmetry, you do not see the rotation symmetry of one crystal. You could not have discovered quasiperiodic materials with x-rays, you had to work with electron microscopy. Electron microscopy, at least in methods that I was using at the time, was not as precise as x-rays. The people that rejected the results of electron microscopy on the grounds that they are not precise were correct, they are not precise, but you did not need the precision to see the rotation symmetry and my diffraction pattern showed that very clearly, you can see clearly the rotation symmetry.

What was the project that you were actually doing, because you weren’t looking for quasicrystals, you were making these alloys. What were you off looking for?

Dan Shechtman: My project … Let me start a little bit earlier. I came to NBS for my first sabbatical from the Technion. This is six years after I became a faculty, on the seventh year we have a sabbatical. I went there and actually stayed for two years, I requested one year of leave of absence. The sponsor was DARPA, Defense Advanced Research Projects Agency. They wanted me to develop aluminum base alloys for aerospace applications. I did it with a technique called rapid solidification in which you take a metal, you melt it and you solidify it, but very quickly, very rapidly. We had some instruments to do that, to solidify. When you rapidly solidify you move away from the /- – -/ stability, it is not /- – -/ to make them stable. You receive structures, meaning atomic arrangements which you cannot receive if you slowly cool.

You capture different structures?

Dan Shechtman: They form, different structures form. I started to work on an alloy that they gave me upon my arrival, it was an aluminum alloy. They said, Oh Danny, before you prepare your own alloys, here is something that we have for you, we already prepared this, so I started to work on aluminum alloys. Then there was a phase there which was close to aluminum six iron that was not stable. I wanted to see how it looks when it is stable, so I prepared alloys from, instead of aluminum iron aluminum manganese and I prepared a series of alloys – 1 % manganese, 2 %, 5 %, 10 % – maybe 10 alloys. In the aluminum 25 % manganese there it was. Let me tell you something that is a little bit educational. The person who sponsored me in DAPA – now this is department of defense of the United States – he knew me, and he said, Danny, you have a very nice proposal which I am sponsoring, but I am telling you run wild. Do whatever you want! Don’t just stick to the proposal, just run wild. What did it mean? You see, aluminum 1 % manganese, maybe up to 5 % manganese can be used for, but 15 %, 25 % is almost powder. You cannot make anything useful for aerospace from that. But I felt free to do whatever I wanted. You start from applications, but you end up in good science.

That’s a lovely thing to bring up because so often we sit talking to Nobel Laureates who have been doing basic science and they have come up with a basic discovery, and naturally people start asking, What is the application? In your case you were doing applied research, and the basic research was your side piece – it’s very nice. Is the lesson to learn from that even when thinking that you are directing people down the applied search tracks there should always be the space for play?

Dan Shechtman: You should look around and pay attention to something odd. When I talk to young students, I can give them ten advice but I always give them one advice. If you want to succeed in something – become an expert in that field. You can start becoming an expert now, when you are a high school student. Choose a subject that may interest you and in today’s world information is regularly available to everybody everywhere. Choose a subject and become an expert. If you have questions call a professor in the university, he will talk to you, he will explain to you. Find out who are the people who are the masters of that field and talk to them. Become an expert and it will carry you a long way.

Because expertise will always be sort out by others?

Dan Shechtman: No, because as an expert you will … When you will discover something you will trust your findings. Also you are right. It pays to become an expert and sometimes it doesn’t. Let me give an example. In my early days in academia, I was going to the US every summer to work there. I am a material scientist and I wanted to be labelled material scientist, but I was labelled as an electron microscopist instead. One summer I called them and asked, Can I come this summer? He said, No, this summer we don’t need any electron microscopist. I said, Now wait, I am a material scientist. No, no, but you are a good electron microscopist. I was labelled as an electron microscopist. Sometimes it is good, sometimes it is not very good to put a label on somebody in a narrow filed.

We’ll come back to quasicrystals in a minute, but I just wanted to make a brief digression into becoming an expert because how did you become an expert yourself, how did you become a material scientist?

Dan Shechtman: Let me tell you. When I was very young, in the fifth grade in elementary school, I was very interested in nature and science. The nature teacher – we had a subject called nature – which is now called science – then it was called nature – said to the children, You know we have a microscope in school, and my eyes opened like that. What? Can you bring it to the class? He said, Yes, of course. The next week he didn’t bring it and the next week he didn’t bring it and I begged him and begged him, so finally he brought it to the class and put it on the table. It was a microscope like this, a very primitive one, but I had never seen one before. He put a sample of a leaf or an insect, I don’t know what it was, I think it was a leaf or something. He said, Dan, you showed an interest in this so you will be first to look. I came and I stood at his desk and I was looking, Wow, it was so amazing. He said, OK Dan, sit down. I said, Wait a minute, I was so fascinated. Then I said, Maybe you could bring it to the class every week or may I come to the warehouse where you store it, can I work on it? No, he said, one time is enough, and he never brought it again.

This was my first encounter with a microscope, it was a small, primitive optical microscope. When I did my master’s degree at the Technion the first transmission microscope arrived at the Technion and I immediately pounced on it. I was circling around when they assembled it, asked so many questions, and looked at it – more like a mechanical engineer than anything else, just wanted to see the construction. Then I became one of the first operators of the electron microscope. At that time we were used to fix the electron microscope ourselves, there was no technician, we did it. People ask me, Did you spend time on the microscope or under the microscope? It was equal time, but I learned how the microscope works, really, learned the technique. Then my PhD was already on electron microscopy.

Again, it underlines that once you found yourself in America observing these odd patterns you knew the instrument inside out and you knew where any such deviation could come from.

Dan Shechtman: I knew where it could come from and suddenly it was right there on the first day, the record showed clearly what I did

There was a gap in your history between the microscope you were showed once and then was taken away and your master’s degree. Somebody else must have encouraged you. Was there one person or someone who pushed you?

Dan Shechtman: Yes, I can say that there was one professor that arrived at my department from Cambridge in England. He was /- – -/ microscopy, one of the first in electron microscopy, David Brandon. He was my thesis supervisor for PhD. I came to him when I did my master and said, Will you instruct me for a PhD and he said, Of course, why not. This is the way we started, and he gave me the first lessons about electron microscopy. He did some other thing that should be told, he introduced me to the masters of electron microscopy of the time. Most of them were from England and from Belgium. They came to visit him and he invited me to his home every time somebody came to visit. He introduced me to this community. This is important, this is a lesson to be learned. Later on, he sent me to an international school of electron microscopy in Erice, Italy – Sicily actually. That was another important thing – send your students to become experts.

Back to quasicrystals. The story is well told in the materials published already, and of course you will be telling the story, I suspect, in your Nobel Lecture in a couple of days’ time and how gradually an understanding of what was generating this aperiodic pattern. I guess we don’t want to go into that in great detail now, but what your discovery of quasicrystals did was to change the definition of how we saw matter. Before then crystals were described in one way as series of repeating units. After quasicrystals it became a much broader definition and that seems to be a truly exciting thing to happen.

Dan Shechtman: Yes. The science of crystallography started in 1912, really the science, by the famous experiments by von Laue, he did x-ray diffraction. It was an amazing experiment because he proved in one experiment that x-rays have /- – -/ and also that solid matter crystals are really organised in planes and the atoms are really nicely ordered. Also, in the alloy that he studied the order was periodic. In those seventy years, from 1912 to 1982, the only crystals that was studied and analysed were periodic. And so a paradigm was evolved that a crystal – a paradigm and a definition – a crystal is order and periodic, anything that is not both ordered and periodic is not a crystal. OK. So here I am with a diffraction pattern and a serial of experiments that show that I have something which doesn’t fit the definition of crystals because it is not periodic. It’s ordered, how do you recognise order, because of the diffraction pattern, but it is not periodic. For three years, 1984-1987, the international union of crystallography did not accept the new findings into the community of crystals, they did not accept it as a crystal. Why? Because our results came from electron microscopy and not from x-rays.

Why couldn’t we do x-ray diffraction? I did x-ray diffraction experiments, a lot of diffraction experiments – the only famous experiments I did was electron microscopy because then you can see single crystals. We didn’t have single crystals large enough for x-rays. It took three years for somebody to grow large enough quasiperiodic crystals. In two laboratories, both in France and in Japan, my colleagues had x-ray diffraction patterns and they sent them to me. In 1987 I presented these results in a meeting of the international union of crystallography in Perth, this is Western Australia. The the community said, OK, Danny, now you’re talking. They established a committee to deal with non-periodic structures and the new definition have emerged. They saw the diffraction pattern not based on the real space based on /- – -/ space. It’s a wonderful definition because it is a humble definition. A humble scientist is a good scientist, open.

So many people, I suppose the majority of people, view sciences providing /- – -/ sort of closing down things – this is how this works, this is how this works. In this case this is a piece of science that says, Well, actually we knew less than we thought we did, it’s going in this direction.

Dan Shechtman: Yes, but this is quite typical in science, we open new avenues all the time. Look at the Nobel Prize in Physics this year – a new avenue. Our understanding of the universe – this year is the year of chemistry …

The international year of chemistry.

Dan Shechtman: Yes, I am honoured to receive the Nobel Prize this year. In two years we will have the year of crystallography, not after von Laue by the way, but after Bragg – this is a different story. Look at the physicists, the large world of astronomy is developing all the time, but so is the small world of the structure of matter, and smaller and smaller is developing in two directions. We reach deeper and deeper into the understanding of elementary particles and of our universe. Do we have only one universe?

Who knows?

Dan Shechtman: People thought before that the earth is the centre of the universe and the stars are to serve us. Then we understood we are just a small piece in a universe. Then suddenly we discovered that we have galaxies, we are not the only galaxies, we have many galaxies, so now we have a universe, why should we assume that we have only one universe? We’re never unique. Science is evolving all the time and rightly so. We should be happy that there are so many mysteries to be solved, our children and grandchildren should also be scientific.

There’s plenty of opportunities out there.

Dan Shechtman: Yes, definitely, the more we know, the more we don’t know.

Last piece dwelling on quasicrystals. They are very small. As you’ve been saying, the crystals you were studying were too small for x-ray diffraction. But quasicrystals in nature are also very small, they have now been found to exist out there.

Dan Shechtman: Yes, indeed.

But in very micro forms, is that correct?

Dan Shechtman: Yes, but no. You can grow large single crystals, you can grow large single crystals as large as my pen. You can grow single quasi periodic materials like this, there is no reason why you shouldn’t. You can make quasi periodic materials in each and every way you make any other material. Up to the recent discovery of Paul Steinhardt and his student of quasi periodic materials in nature most of the quasi crystals, if not all, were intermetallic compounds, so they are intermetallic compounds – nothing very special about that – but the structure is very special. They are not small, you can grow them large.

What do you hope that they will bring mankind, because there’s a lot of talk of application for them.

Dan Shechtman: The best application is here in Sweden, in my opinion, a company named Sandvik, you probably know of Sandvik, they have headquarter in Sandviken. They have a steel which is extremely strong, it is a wonderful steel and it is strengthened by quasiperiodic particles – this is one use. In order to use a material you need some property that will be special, a special property. We look for these special properties and we combine them with the price of the material and with the corrosion resistance of the material and the beauty of the material. Once you find a good combination you can start using the material. I wouldn’t get the Nobel Prize for the applications but there are a few applications that are there and there will be application /- – -/. Not necessarily in the realm of materials. Maybe in optics, maybe in magnetic properties. These are not unique materials and just bringing to the different sciences the new order, which is not periodic, it can be used. Look at what’s happening in the field of optics today with quasi periodic material, it’s quite amazing.

There are possibilities. Thank you very much indeed. I am afraid we have run out of time. It has been a great pleasure to speak to you and I wish you a very enjoyable Nobel Week.

Dan Shechtman: Thank you very much. A pleasure to be here.

Thank you.

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