What is glass?
A transparent alloy of a mixture of various silicates. Also, to obtain glass, the raw material must necessarily contain oxides of silicon, boron, lead - these are glass-forming oxides. The raw materials for glass production include quite a lot of materials, but conventionally, its composition is expressed by the formula Na2 x CaO x 6SiO2.
Glass is a liquid with a very high viscosity index. Glass is not a substance, but rather an aggregate state of matter. It is generally accepted to call an alloy glass, products from which are inserted into window openings. In fact, even metal alloys can have glass condition.
Glass is a state of matter that occurs when a supercooled liquid, upon rapid cooling, does not have time to crystallize and reaches a temperature when its molecules, atoms or other structural units are unable, due to the energy of thermal motion, to overcome the energy barrier of jumping from its current position to a new one. ... This leads to two consequences: the state that has arisen can exist for an indefinitely long time (since for crystallization the structural elements of the liquid must be arranged in a certain order and oriented in the necessary way), and the viscosity approaches the viscosity of solids.
Glass is usually formed when the melt is already sufficiently viscous at the melting point, which is usually a consequence of the fact that its structure consists of polymer chains or networks of structural elements (for example, in the case of silicate glasses, these are silicon-oxygen tetrahedrons that form chains) and mobility the melt is due to the fact that due to thermal energy, the chains are broken and reconnected. And the lower the temperature, where the melt is still thermodynamically stable, the higher the viscosity of the melt in this region and the less the tendency of the melt to crystallize during supercooling. Therefore, the regions of the most stable glass formation in multicomponent systems are the vicinity of eutectics.
Among the oxides, one can distinguish glass-forming oxides, which in themselves are prone to the formation of glasses. These are oxides of boron, germanium, silicon, phosphorus, arsenic, tellurium, which are characterized by the above-described polymer structure. Similarly, there are glass-forming fluorides, halides, chalcogenides, as well as simple substances (the most typical case is selenium). polymeric structure, with glass-forming oxides give very wide regions of stable glasses, often not reaching only a few percent of the second component.
Glass is a very versatile material with specific properties. Its condition is realized in various natural and artificial materials.
Physically, glass can have some of the properties of solids, although inorganic glasses can have properties like a supercooled liquid with high viscosity.