Energy & Green Tech

Flexible thinking on silicon solar cells

Crystalline silicon solar panels could be just as effective when incorporated into stretchy wearable electronics or flexible robot skin as they are when used as rigid rooftop panels. KAUST researchers have devised a way to ...


Punching holes in opaque solar cells turns them transparent

Researchers in Korea have found an effective and inexpensive strategy to transform solar cells from opaque to transparent. Existing transparent solar cells tend to have a reddish hue and lower efficiency, but by punching ...


Using artificial intelligence to engineer materials' properties

Applying just a bit of strain to a piece of semiconductor or other crystalline material can deform the orderly arrangement of atoms in its structure enough to cause dramatic changes in its properties, such as the way it conducts ...

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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.

This text uses material from Wikipedia, licensed under CC BY-SA