Once a source of ridicule, a curious structure known as a quasicrystal has earned its discoverer, of the Technion Israel Institute of Technology in Haifa, this year鈥檚 .
Materials with this structure are relatively new to science, and still something of a mathematical curiosity. But they have already found uses in steel armour, non-stick frying pans and devices in cars for recycling waste heat into electricity.
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Back in 1982, Shechtman鈥檚 claim to have discovered such a substance provoked so much controversy and ridicule that his boss asked him to leave the lab where he chanced on the discovery, at the US National Institute of Standards and Technology in Gaithersburg, Maryland.
Shechtman鈥檚 sin was to identify a crystal that broke a golden rule of chemical symmetry. His alloy of aluminium and manganese lacked an infinitely repeating base pattern, such as four atoms arranged as a cube. Instead, the atoms were arranged in a pattern that was orderly, but never repeated itself exactly.
Islamic inspiration
Eventually, it emerged that the atoms in the alloy were arranged like patterns called Penrose tiles, after mathematician Roger Penrose, who devised them in the mid-1970s.
Similar non-repeating patterns have since been identified in Islamic designs at the 14th-century Alhambra palace in Granada, Spain, and the 15th-century Darb-i Imam shrine in Isfahan, Iran. They also crop up in works by artists such as M.聽C. Escher.
Naturally quasi
Once Shechtman鈥檚 discovery was accepted and his results published, other chemists began to discover crystals with other symmetries that had been assumed impossible. Finally, in 1992, the International Union of Crystallography rewrote its definition of crystals, a final vindication of Shechtman鈥檚 observation, and a snub to his critics 鈥� including Linus Pauling, himself a double Nobel laureate.
The patterns were of mathematical interest too. The quasicrystal is related to the Fibonacci sequence, in which each number is the sum of the two preceding it, such as 1,聽1,聽2,聽3 and so on. The terms in this sequence yield the 鈥済olden ratio鈥� tau, and it turns out that tau governs the distances between atoms in quasicrystals.
In 2009, the first natural quasicrystal was discovered in samples from the Khatyrka river in eastern Russia. Named icosahedrite, it is a mineral consisting of aluminium, copper and iron.
Non-stick crystal
Quasicrystals have practical applications. They鈥檙e hopeless at conducting heat, but because they convert it into electricity they are ideal as thermoelectric materials that can recycle heat. Automotive researchers are developing them for capturing waste heat in cars.
They are also a key components of a type of steel armour in which the rock-hard steel quasicrystals are embedded in a softer type of steel. In addition, they are being developed as non-stick materials for frying pans and as components in light-emitting diodes.
In a warning to establishment scientists, the academy highlighted the importance of Shechtman鈥檚 originality. 鈥淓ven our greatest scientists are not immune to getting stuck in convention,鈥� it says. 鈥淜eeping an open mind and daring to question established knowledge may in fact be a scientist鈥檚 most important character traits.鈥�
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