| 单词 | hexagonal symmetry |
| 释义 | > as lemmashexagonal symmetry 3. Crystallography. Designating one of the principal systems of crystallization, which is referred to three lateral axes, normally inclined to each other at 60°, and a vertical axis at right angles to these and differing from them in length. Also, Of or belonging to this system. hexagonal close-packed adj., applied to a type of crystal structure or lattice with hexagonal symmetry in which each ion or atom has twelve equidistant neighbours; so hexagonal close-packing (see quot. 1917); hexagonal symmetry, the symmetry of a figure or body that coincides with its original position after rotation about an axis through an angle of 60° or any multiple of this. ΘΚΠ the world > matter > chemistry > crystallography (general) > crystal (general) > crystal systems > [adjective] > hexagonal hexagonal1837 the world > matter > chemistry > chemical structure or stereochemistry > [noun] > atomic framework or arrangement skeleton1907 hexagonal close-packing1917 1837 J. D. Dana Min. (1844) ii. 35 Hexagonal System. The vertical solid angles of the rhombohedron are formed by the meeting of three equal planes. 1878 H. P. Gurney Crystallogr. 38 The line of intersection of six symmetral planes is an axis of hexagonal symmetry. 1895 N. Story-Maskelyne Crystallogr. Index Hexagonal axes. 1917 Physical Rev. 10 678 The so-called hexagonal close-packing..is one of the two alternative arrangements which the atoms would assume if they were hard spheres and were forced by pressure into the closest possible packing. 1920 Science 3 Sept. 228/1 The arrangement of atoms in zinc is like that in magnesium, namely: hexagonal close packed. 1966 L. G. Bassett et al. Princ. Chem. iii. 171 The difference between hexagonal close packing and face-centered close packing arises from the two arrangements for atoms in the third layer. < as lemmas |
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