Sublimation (chemistry)

Examples

  Some materials (such as cadmium) will sublimate at low pressures and thus may be a problem encountered in high-vacuum applications.

enthalpy of vaporization.

Other substances, such as ammonium chloride, appear to sublime because of chemical reactions. When heated, it decomposes into hydrogen chloride and ammonia, which quickly react to reform ammonium chloride.

Sublimation purification

  Sublimation is a technique used by sublimation apparatus‎.

Uses

Frost-free freezers work by having a fan and air circulation inside the freezer. The sub-zero temperature combined with the air circulation that keeps the air arid significantly accelerates the sublimation process. This keeps freezer walls and shelves free of ice, although ice-cubes will continually sublimate.

Dye sublimation is also often used in color printing on a variety of substrates, including paper. A small heater is used to vaporize the solid dye material, which then solidifies upon the paper. As this type of printer allows extremely fine control of the primary color ratios it is possible to obtain a good quality picture even with relatively low printer resolution, as compared to other printer types of similar resolution. Standard black and white laser printers are capable of printing on plain paper using a special "transfer toner" containing sublimation dyes which can then be permanently heat transferred to T-shirts, hats, mugs, metals, puzzles and other surfaces.

In core alchemical processes.

In the Fast-Freeze, Deep-Etch technique, samples (for example, tissue samples) are rapidly frozen in liquid nitrogen and transferred to a vacuum device in which surface ice is sublimed. This effectively etches the sample surface, revealing the preserved 3D structure of the hydrated material. A rotary shadowed surface replica can then be obtained via electron microscopy.

Sublimation is also used to create freeze-dried substances, for example tea, soup or resuspend than one that is produced from a liquid system, and the low temperatures involved cause less damage to sensitive or reactive substances.