News tagged with crystallinity
An unlikely route to ferroelectricity
(Phys.org) -- Ferroelectricity, which was first observed in the 1940s, is an interesting phenomenon involving the spontaneous (non-induced) formation of charge polarization (separation of charge) in certain ...
May 18, 2012 |
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Group uses controlled cracking for nanofabrication
(Phys.org) -- When creating nanomaterials, cracking is generally considered a problem; it usually means something has gone wrong and the result, as with other material making processes such as glass or ceramics, ...
May 10, 2012 |
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Novel battery system could reduce buildings' electric bills
The CUNY Energy Institute, which has been developing innovative low-cost batteries that are safe, non-toxic, and reliable with fast discharge rates and high energy densities, announced that it has built an operating prototype ...
Technology / Energy & Green Tech
May 08, 2012 |
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Thanks for the memory: More room for data in 'phase-change' material
A team led by Johns Hopkins engineers has discovered some previously unknown properties of a common memory material, paving the way for development of new forms of memory drives, movie discs and computer systems ...
May 03, 2012 |
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Creating nanostructures from the bottom up
Microscopic particles are being coaxed by Duke University engineers to assemble themselves into larger crystalline structures by the use of varying concentrations of microscopic particles and magnetic fields.
Apr 24, 2012 |
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Looking through the glass transition on an ultrafast timescale
(Phys.org) -- When chemists look at a drinking glass filled with water and a few ice cubes, it's not clear to them whether the glass is more like the water or the ice.
Apr 16, 2012 |
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New surface coatings could inhibit buildup of methane hydrates that can block deep-sea oil and gas wells
During the massive oil spill from the ruptured Deepwater Horizon well in 2010, it seemed at first like there might be a quick fix: a containment dome lowered onto the broken pipe to capture the flow so it could be pumped ...
Apr 11, 2012 |
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The earliest stages of planet formation
(PhysOrg.com) -- Small dust particles in a disk of gas around a young star, according to current models, gradually coagulate during the first million years until kilometer-sized objects are formed. These in ...
Mar 26, 2012 |
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New approach aims to slash cost of solar cells
Solar-powered electricity prices could soon approach those of power from coal or natural gas thanks to collaborative research with solar start-up Ampulse Corporation at the U.S. Department of Energy's (DOE) ...
Technology / Energy & Green Tech
Mar 06, 2012 |
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Plant toughness: Key to cracking biofuels?
Along with photosynthesis, the plant cell wall is one of the features that most set plants apart from animals. A structural molecule called cellulose is necessary for the manufacture of these walls. Cellulose is synthesized ...
Feb 21, 2012 |
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Materials that shrink when heated
One common reason that people with fillings experience toothache is that their fillings expand at a different rate to the original tooth when, for example, drinking a hot drink. Contrary to intuition, however, ...
Feb 09, 2012 |
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Hydrogen from acidic water: Researchers develop potential low cost alternative to platinum for splitting water
A technique for creating a new molecule that structurally and chemically replicates the active part of the widely used industrial catalyst molybdenite has been developed by researchers with the Lawrence Berkeley ...
Feb 09, 2012 |
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Manipulating the texture of magnetism
Knowing how to control the combined magnetic properties of interacting electrons will provide the basis to develop an important tool for advancing spintronics: a technology that aims to harness these properties ...
Feb 03, 2012 |
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New zeolite material may solve diesel shortage
World fuel consumption is shifting more and more to diesel at the expense of gasoline. A recently published article in Nature Chemistry by a research team at Stockholm University and the Polytechnic University of Valencia in Spa ...
Feb 01, 2012 |
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Hacking the SEM: Crystal phase detection for nanoscale samples
(PhysOrg.com) -- Custom modifications of equipment are an honored tradition of the research lab. In a recent paper, two materials scientists at the National Institute of Standards and Technology describe how ...
Jan 25, 2012 |
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Crystallinity
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 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.
For more information about Crystallinity, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
