Crystalline structure of Ag-Al-quasic crystal. Photo of a Ho-Mg-Zn quasic crystal.
Quasic crystals are crystals in which the atoms are arranged in an apparently regular but in reality in an aperiodic structure. In other words, a repetitive structural part is not recognizable, as with normal crystals, but there is some regularity in the structure. In quasi-crystals, there is a 5- or 10-fold symmetry (such as a 10-speed axis). However, this is impossible with ordinary crystals, with only 1-, 2-, 3-, 4- or 6-axis rotational axes.
The structure was discovered by experimental research on April 8, 1982 by Daniel Shechtman, who received the Nobel Prize for Chemistry in 2011. Shechtman had cooled a molten mixture of aluminum and manganese extremely quickly and examined its structure with an electron microscope. From this he concluded that the material at atomic level showed a 5-fold symmetry. Until then, it was assumed that crystals could not possess this form of symmetry. In 1984, Paul Steinhardt and Dov Levine made a major contribution to the clarification of the structures. Literature
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