Silicon and silicate materials
Amorphous silicon powder in powder state, with strong chemical reactivity, easy to combine with oxygen, severe reaction will cause burning, silicon is easy to react with hydrofluoric acid and dissolved, thus industrial cleaning silicon impurities commonly used hydrofluoric acid. Silicon is an important semiconductor material, chemical property is more stable, but soluble in strong acid and hydrofluoric acid; under high temperature conditions, its surface can react with oxygen and chlorine in the air; in the air conditions can directly combine with hydrogen. Both amorphous silicon powder and crystalline silicon at high temperature can dissolve in aqueous solution of alkali and produce hydrogen.
Crystalline can be divided into monocrystalline silicon and polycrystalline silicon two kinds. There is only one nuclei in monocrystalline silicon, is an important material for manufacturing semiconductor device. While manufacturing semiconductor materials, need to turn the usually obtain polycrystalline silicon into monocrystalline silicon, heated and melted the polycrystalline silicon, and introduce silicon crystal nuclei in it, then the monocrystalline silicon nucleus grows into a single piece of silicon, that is the silicon crystal. Then cut off the rod single crystal silicon cross sectioned along can be obtained single crystal silicon.
Silicon is a black opaque solid. Purity of 99.93% monocrystalline silicon, melting point (1415±2), the hardness is high. The crystal lattice is the same as diamond, conductivity is similar with ishiguro. Crystalline silicon surface is hydrophobic, after oxidized become hydrophilic. The wafer manufactured by single crystal silicon during machining the surface will show up deformed layer, because a lot of dirt will be attached on this deformed layer and have adverse effects on the performance of semiconductor material, must be removed. Cleaning semiconductor material is a relatively complex process, also a characteristic of semiconductor processing.
Natural silicates are made of silicon dioxide and various metal oxides salts (including Na, K, Ca, Mg, Al, Fe and other metal), widely distributed in nature, rocks, soil, minerals. Feldspar, stone, kaolinite, mica, asbestos, talc and so on are the main component of natural mineral silicates, their chemical structure is very complex and often regard them as silica and metal oxide of composite oxide.
Natural silicates are industrially important materials, electricity is an important industrial raw material. Natural silicate as the main raw material, through high-temperature processing made into a variety of silicate materials including glass, ceramic, cement, bricks, refractory, ceramic, fiberglass, cast stone, abrasives, high temperature resistant inorganic coatings. Because of in the structure, silicon-oxygen tetrahedron as the skeleton, silicon-oxygen bond energy is high, so most of silicate material has a high mechanical strength, high temperature resistant characteristics.
The chemical composition of glass is more complex, wherein the silica is the major component constituting the glass skeleton. High purity crystalline state natural mineral called silica crystal. Its physical and chemical properties of stability are unlike ordinary glass plasticity. If melted and quenched the crystal pure silica and other minerals will get the quartz glass. In the quench process, the silica crystal structure damaged, so its melting point is lower than the crystal, has a very low coefficient of thermal expansion, and has plasticity, a special unique properties glass.
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