| abstract | - Vitrification is usually achieved by heating materials until they liquidize, then cooling the liquid, often rapidly, so that it passes through the glass transition to form a vitrified solid. Certain chemical reactions also result in glasses. In a wider sense, the embedding of material in a glassy matrix is also called vitrification. An important application is the vitrification of radioactive waste to obtain a stable compound that is suitable for ultimate disposal. In terms of chemistry, vitrification is characteristic for amorphous materials or disordered systems and occurs when bonding between elementary particles (atoms, molecules, forming blocks) becomes higher than a certain threshold value. Thermal fluctuations break the bonds; therefore, the lower the temperature, the higher the degree of connectivity. Because of that amorphous materials have a characteristic threshold temperature termed glass transition temperature (Tg): below Tg amorphous materials are glassy whereas above Tg they are molten. The most common applications are in the making of pottery, glass, and some types of food, but there are many others, such as the vitrification of an antifreeze-like liquid in cryopreservation.
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