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Classical theory of crystals reduces crystals to point lattices where each point is the center of mass of one of the identical units of the crystal. The structure of crystals can be analyzed by defining an associated group. Quasicrystals, on the other hand, are composed of more than one type of unit, so, instead of lattices, quasilattices must ...
The book is divided into two parts. The first part covers the history of crystallography, the use of X-ray diffraction to study crystal structures through the Bragg peaks formed on their diffraction patterns, and the discovery in the early 1980s of quasicrystals, materials that form Bragg peaks in patterns with five-way symmetry, impossible for a repeating crystal structure.
Quasi-crystals are supramolecular aggregates exhibiting both crystalline (solid) properties as well as amorphous, liquid-like properties.. Self-organized structures termed "quasi-crystals" were originally described in 1978 by the Israeli scientist Valeri A. Krongauz of the Weizmann Institute of Science, in the Nature paper, Quasi-crystals from irradiated photochromic dyes in an applied ...
Pages for logged out editors learn more. Contributions; Talk; Quasi-dihedral group
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A standard example is the "electron quasiparticle": an electron in a crystal behaves as if it had an effective mass which differs from its real mass. On the other hand, a collective excitation is usually imagined to be a reflection of the aggregate behavior of the system, with no single real particle at its "core".
Pages for logged out editors learn more. Contributions; Talk; Quasi-crystal
Twenty of the 32 crystal classes are piezoelectric, and crystals belonging to one of these classes (point groups) display piezoelectricity. All piezoelectric classes lack inversion symmetry . Any material develops a dielectric polarization when an electric field is applied, but a substance that has such a natural charge separation even in the ...