When water is cooled below its normal freezing point, it normally freezes to form hexagonal ice, or Ice I, though it can exist in other solid forms. Solid water can exist in a number of non-crystalline forms; amorphous solid water (ASW or "low density glass," 0.94 grams per cubic centimeter), is formed from the slow deposition of water vapor, at less than 0.2 nm per second, on a very cold metal crystal surface below 120 K. If it is very pure and cooled carefully, it may be supercooled to about -42 °C. If water is cooled very rapidly then it forms an amorphoric glass.
These amorphous ices are not required to obey the 'ice rules' and may contain a significant number of dangling bonds.
The relationship between these supercooled waters is not easily investigated as there is an unobtainable 'no man's land' in the physical conditions where no liquid phase can be found; although ESR indicates that a small fraction of the water molecules may be 'free' coexisting with cubic ice between about 160-230 K [1005].
If this puckering of the water dodecahedra is random with respect to the number of inner water molecules, this would produce a more disordered structure than LDA in line with the thermal conductivity data [617] and the recent finding of HDA's lack of a unique structure [618].
For instance, common window glass is an amorphous ceramic, many polymers (such as polystyrene) are amorphous, and even foods such as cotton candy are amorphoussolids.
Amorphous materials are often prepared by rapidly cooling molten material.
Amorphoussolids produced by other routes, such as ion implantation and thin-film deposition are, technically speaking, not glasses.
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