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crystallite|ˈkrɪstəlaɪt|
[f. Gr. κρύσταλλ-ος crystal + -ite.]
†1. Min. A name applied to the somewhat crystalline form and structure taken by igneous rocks, lavas, etc. upon fusion and slow cooling.
1805Sir J. Hall in Trans. Soc. Edin. V. 43 (Whinstone and Lava). 1807T. Thomson Chem. (ed. 3) II. 486 Sir James Hall..has given the whin in this last state the name of crystallite, a term suggested by Dr. Hope..The rock on which Edinburgh Castle is built fuses at the temperature of 45° Wedgewood. By rapid cooling it is converted into a glass which melts at 22°; by slow cooling into a crystallite which melts at 35°. Ibid. 488 In the crystallite, the component parts having had time to combine according to their affinities. 1852Th. Ross tr. Humboldt's Trav. I. 101 The fibrous plates of the crystalites of our glass-houses.
2. a. A term proposed by Vogelsang for aggregations, in various forms, of the globulites seen in thin sections of rock under the microscope; Formerly by some identified with, but now distinguished in sense from, microlith, -lite: a crystallite is of smaller size, does not polarize light, and cannot be referred to any definite species of mineral.
Occas. used (following Vogelsang) for ‘embryonic crystals’ in other substances (in quot. 1914 the word denotes a branched crystal or dendrite such as forms in freezing metal).
1878Lawrence tr. Cotta's Rocks Class. 67 Many rocks..more or less filled with very minute crystals, or so-called crystallites. 1881J. W. Judd Volcanoes iii. 53 Those minute particles of definite form, which the microscope has revealed in the midst of the glassy portions of lava, have received the name of microliths, or crystallites. 1910Encycl. Brit. VII. 568/2 Crystallites may also be produced by allowing a solution of sulphur in carbon disulphide mixed with Canada balsam to evaporate slowly. 1914Jrnl. Inst. Metals XI. 65 Most metals only exceptionally form simple polyhedral crystals, but by preference assume the form of branched crystallites. A theory of crystallites was proposed by Vogelsang, who made a special study of these structures in vitreous rocks,..in blast-furnace slags, and in artificial preparations. He observed that by cooling solutions of sulphur in viscous solvents, minute..globules were obtained, which..gradually developed crystalline outlines, so that the typical branched crystallites were thus produced. He therefore..regarded crystallites as ‘embryonic crystals’. 1926G. W. Tyrrell Princ. Petrol. v. 81 Crystallites are embryo crystals, not yet organized to full crystalline status... Microlites are somewhat larger bodies which can be definitely recognised as minute crystals. 1953L. E. Spock Guide Study of Rocks iv. 59 Typical fresh obsidian is glossy and black, owing its darkness to closely spaced crystallites. 1958A. D. Merriman Dict. Metallurgy 49 Crystallite... The term is often used in reference to the tiny incipient crystals forming on the solidifying of metals and alloys. 1966McGraw-Hill Encycl. Sci. & Technol. VII. 10/2 Crystallites..are the most rudimentary forms [of rock grains] and abound in glassy rocks in which rapid consolidation has arrested further growth.
b. An individual crystal or grain in a metal or other polycrystalline substance; also, a part of a quasi-single crystal in which the orientation is uniform and the structure homogeneous. (Orig. an application of the word in the prec. sense, as in quot. 1914.)
1914Jrnl. Inst. Metals XI. 64 The ‘crystal grains’ of ordinary cast metals arise in this way, their boundaries being produced by the mutual interference of neighbouring crystallites. 1920Chem. Abstr. XIV. 3006 The dissoln. of the eutectic..occurs at the boundaries of the crystallites even of ‘pure’ metals. 1938J. Newton Introd. Metallurgy ii. 27 These small units are individual crystals of the metal or alloy and are called crystallites, crystal grains, or simply grains. 1962Simpson & Richards Junction Transistors iii. 39 To minimize the formation of improperly oriented crystallites on the surface of the main crystal..the seed is slowly rotated as it is withdrawn. 1963W. G. Burgers in J. J. Gilman Art & Science of growing Crystals xxii. 417/1 A normal piece of metal..is usually fine-grained and built up of crystallites (grains) often a few hundredths of a millimeter in diameter.
3. poetically. = crystal n. 2.
1838S. Bellamy Betrayal 150 Write Upon her walls of crystallite Salvation!
4. A minute part of cellulose or other polymers having the highly ordered structure characteristic of a crystal. Cf. micelle.
1926Jrnl. Physical Chem. XXX. 457 Cellulose, in its natural condition, consists of aggregates of crystallites as found in the bast fibres, seed hairs, and other plant tissue as well as in the animal body. 1931New Phytologist XXX. 4 In such fibres as ramie the crystallites are arranged parallel to each other. 1932Proc. R. Soc. B. CIX. 449 The cell-wall of Valonia ventricosa is found by X-ray methods to be built up of two main sets of cellulose chains which form crystallites crossing at an angle. 1946E. I. Valko in J. Alexander Colloid Chem. VI. xxix. 595 A single macro⁓molecule can..traverse disorganized regions, so that it belongs to different crystalline regions. As a consequence, the size of the organized regions, i.e., the ‘crystallites’, is not determined by the length of the macromolecule. 1948Schmidt & Marlies Princ. High-Polymer Theory & Pract. ii. 54 In high polymers these crystallites are not all of the same size and do not possess well-defined faces or edges. 1965Bell & Coombe tr. Strasburger's Textbk. Bot. (new ed.) i. i. 53 (caption) Diagram illustrating the micellar structure of cell walls... Linear macromolecules are grouped to form micellae or crystallites. 1966M. L. Miller Struct. Polymers x. 493 Each of these crystallites was supposed to consist of a bundle of parallel chains,..with each crystallite so small that a single molecule passed through several crystals... A modern view regards highly crystalline polymers..as a single crystalline phase with defects. |