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Look up crystallinity or crystalline in Wiktionary, the free dictionary.

Crystallinity refers to the degree of structural order in a solid. In a crystal, the atoms or molecules are arranged in a regular, periodic manner. The degree of crystallinity has a big influence on hardness, density, transparency and diffusion. In a gas, the relative positions of the atoms or molecules are completely random. Amorphous materials, such as liquids and glasses, represent an intermediate case, having order over short distances (a few atomic or molecular spacings) but not over longer distances.

Many materials (such as glass-ceramics and some polymers), can be prepared in such a way as to produce a mixture of crystalline and amorphous regions. In such cases, crystallinity is usually specified as a percentage of the volume of the material that is crystalline. Even within materials that are completely crystalline, however, the degree of structural perfection can vary. For instance, most metallic alloys are crystalline, but they usually comprise many independent crystalline regions (grains or crystallites) in various orientations separated by grain boundaries; furthermore, they contain other crystal defects (notably dislocations) that reduce the degree of structural perfection. The most highly perfect crystals are silicon boules produced for semiconductor electronics; these are large single crystals (so they have no grain boundaries), are nearly free of dislocations, and have precisely controlled concentrations of defect atoms.

Crystallinity can be measured using x-ray diffraction, but calorimetric techniques are also commonly used.

Rocks crystallinity

Geologists describe four qualitative levels of crystallinity:

holocrystalline rocks are completely crystalline;
hypocrystalline rocks are partially crystalline, with crystals embedded in an amorphous or glassy matrix;
hypohyaline rocks are partially glassy;
holohyaline rocks (such as obsidian) are completely glassy.

References

Oxford dictionary of science, 1999, ISBN 0-19-280098-1.

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Annealing effect on the generation of dual mode acoustic waves in inclined ZnO films.

Pang HF, Fu YQ, Hou R, Kirk KJ, Hutson D, Zu XT, Placido F.SourceSchool of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, PR China; Thin Film Centre, Scottish Universities of Physics Alliance (SUPA), University of the West of Scotland, Paisley PA1 2BE, UK.
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Variation of the effect of calcium phosphate enhancement of implanted silk fibroin ligament bone integration.

Shi P, Teh TK, Toh SL, Goh JC.SourceDepartment of Bioengineering, National University of Singapore, Singapore; NUS Tissue Engineering Programme, National University of Singapore, Singapore; Department of Orthopedic Surgery, National University of Singapore, Singapore.
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Japanese Journal

Effect of Hydrogen Dilution on the Nanostructural and Electrooptical Characteristics of Hydrogenated Nanocrystalline Silicon Thin Films Prepared by Plasma Enhanced Chemical Vapor Deposition

Nam Hee-Jong,Son Jong-Ick,Cho Nam-Hee
Jpn J Appl Phys 52(1), 01AD06-01AD06-7, 2013-01-25
… The increased crystallinity can be explained by the predominance of Si--H bonds in the films. …
NAID 150000106319

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… Here we aim to study the crystallinity and electrical properties of hydrogenated NMC-ZnO films in correlation with substrate temperature and H2 flow rate. … Furthermore, the crystallinity and surface morphology of the hydrogenated NMC-ZnO films are improved by increasing substrate temperature to 400 °C, where the smallest integral breadth of (002) 2\theta--\omega scans of 0.83° has been obtained. …
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