What is the difference between crystalline silicon and silica?
Silica dioxide, also known as silica (quartz sand), chemical formula SiO2. There are two kinds of crystalline silica and amorphous silica in nature. Crystalline silica is divided into three kinds: quartz, scale quartz and square quartz because of their different crystal structures. Pure quartz is colorless crystal silica, large and transparent prism like quartz called crystal. If they contain trace impurities in crystal with different colors, amethyst, Citrine, topaz etc.. Ordinary sand is quartz fine sand, a (iron impurity) and white sand (less impurities, Jiao Chunjing). Silica crystal, silicon atoms with 4 valence electrons and 2 oxygen atoms form 4 covalent bonds, silicon atoms in the tetrahedral centers, 4 vertices of 4 oxygen atoms in the tetrahedron, the crystal is a giant molecule, SiO2 is simplest composed of a single silica molecular, is only expressed the number of atoms of silicon and oxygen ratio of the silica crystals. In SiO2, the bond of Si - O bond is very high, the melting point and boiling point are higher (melting point 1723, boiling point 2230 Celsius). Natural earth diatomite is amorphous silica, is the remains of low water plants diatom, white solid or powder, porous, light and soft solid, strong adsorption.
Stone (quartz) is a general term for quartz, quartzite and quartz sandstone. Acid refractory brick, mainly used in metallurgical industry. Pure silica can be used as quartz glass or refined monocrystalline silicon. The chemical industry is used in the preparation of silicon compounds and silicates, and can also be used as a filler for sulfuric acid towers. Building materials industry is used in glass, ceramics, Portland cement and so on. It can be used as raw material for smelting ferroalloy such as industrial silicon.
Crystalline silicon is a simple silicon, which is widely used in semiconductor, solar photovoltaic cells and so on.
Silicon is found in nature in large amounts of silicate ores and quartz ores. The earth is mainly composed of the mineral world, abundance in the crust is 27.7%, in all of the elements in the second, with the formation of silica SiO2 oxygen and silicon most elements in the crust, the crust accounted for 87% of the total mass. The difference between monocrystalline silicon and polycrystalline silicon is that when the molten silicon is solidified, the silicon atoms are arranged in a number of nuclei with diamond lattices, and if these nuclei grow into crystalline grains with the same orientation, then monocrystalline silicon is formed. If these nuclei grow into crystalline faces with different orientations, then polycrystalline silicon is formed.
