Almost 30 years after Daniel Shechtman noticed something weird in his lab, he finally won a Nobel Prize for chemistry. But before that, his strange discovery resulted in him being asked to leave the lab for bringing disgrace upon his colleagues.
What caused all this upheaval? An odd pattern. Nothing more. See how a seemingly minor idea blew up into a huge controversy.
Top image: Lejyby on Flickr.
In 1982 Daniel Shechtman was quietly told to move out of the US National Institute of Standards and Technology. One would think he was eating plutonium to try to become the Hulk, but no. All he did was peer through an electron microscope at a pool of rapidly cooling pool of aluminum and manganese and notice something weird. The diffraction pattern of the electrons indicated that atoms were arranging themselves into little five-'pointed' shapes. Each of the 'points' was a little atom, and whole structure was cooling so that the points were locked together in something that could not quite be called a pattern. A pattern repeats itself regularly, and these shapes didn't. And yet there weren't any gaps or openings either. Little 'glue atoms' filled up the spaces and left the entire thing locked in a stable structure.
Two and Three Dimensional Patterns
Which, the lab reasonably argued, was ridiculous. The idea was as silly as a someone coming in to put in tiles on your floor and bringing, say, pentagonal tiles, saying they would work as well as squares. Rectangles, triangles, squares, hexagons, the tiles we've all seen locking together on shower floors and kitchen counters, can fill all the available space. Put pentagons, or anything else on the floor and, well, you might as well try to tile your floor in circles. They're not going to fit together. You'll have gaps. You need an orderly pattern to fit all those gaps.
But you'd get your skepticism thrown in your face (along with a couple of tiles) if that person had brought Penrose Tiling. Penrose Tiles are named after Roger Penrose, who studied them in the seventies. Penrose Tiles consist of complementary shapes that fit together, with no gaps, but in a decidedly non-periodic way. Rotate, say, a floor tiled with squares ninety degrees and someone who just came in would never know it was moved. Rotate a floor full of hexagons or triangles the right degree and, once again, you'll fool an onlooker. The patterns can be twisted to certain angles and look identical because they are symmetrical through certain angles. Penrose Tiles never settle into a pattern. Each part of the tiled floor looks different from the other. If you were to rotate the floor, it would look completely different. And yet despite the fact that there's no pattern, there's no gap in coverage.
(Incidentally, Penrose Tiles really earned their place in scientific legitimacy when they were shown to follow that most ancient scientific principle - not being named after the person who actually invented them. Some of the most beautiful Penrose Tile works are in ancient Islamic buildings, where complicated tiling covered the walls long before Roger Penrose was ever born.)
But that's two dimensions. Shechtman was talking about three dimensional crystal lattices with a strange kind of order and stability, but no repeating structure. That was just silly.
And yet, it was true. Slowly, surely, more such structures were created in labs. Dubbed quasicrystals, because they didn't have the periodicity of crystals but did have their locked structure, the things were made in ever-increasing numbers.
It was in 2007 that quasicrystals stopped being a thing that could be made and started being a thing that could be found in nature. Looking over geology samples, scientists found an alloy of aluminum, copper and iron that had been lifted from a river in Russia. The thing had come from outer space, had lain on Earth for quite some time, and was, when they examined its structure, quite clearly a quasicrystal. It had been formed under high pressures, possibly before the Earth had even been formed. But it had been formed naturally.
Uses of Quasicrystals
This alone might not have been enough to earn a Nobel Prize, but it turns out that quasicrystals are quite useful. They're bad conductors of heat and electricity, and thus they're good insulators. They're strong and hard, but, if they're made right, not brittle.
Quasicrystals were first put to work in delicate medical equipment that couldn't be allowed to deform or break during crucial surgeries. They then hopped to a more pedestrian use. Do you like nonstick pans but hate the thought that you're going to be eating teflon as soon as the first scratches in the coating appear? Quasicrystals are said to be so smooth that their coefficient of friction is roughly that of 'a diamond gliding over a diamond film.' They make scientists go poetic. And they don't chip, scratch, or break. They're too tough to be scratched off a pan with a spatula. There actually is quasicrystal-coated cookware out there.
People are working on quasicrystals to be used in solar panels. Solar panels have to take in a great deal of light, convert it to heat, and keep the heat instead of re-emitting it into the atmosphere. Generally good conductors reflect heat out, while poor ones retain it. A layer of quasicrystal can keep heat well inside a panel, cutting re-emmittance down to 2.5 percent. The thing that supposedly didn't exist might wind up doing everything from heating our food, to cooking it, to patching up our hearts when we eat too much of it.
Electron Diffraction of Quasicrystal: Materials Scientists
Image of Archway: Physics World
Image of Silver Crystal: Ameslab