Silicon dioxide, also known as silicon dioxide, is an oxide of silicon with the chemical formula SiO2, most commonly found in nature in quartz and in various living organisms. [5][6] Silica is the main constituent of sand in many parts of the world. Silica is one of the most complex and abundant families of materials, occurring as compounds and synthetic products of many minerals. Well-known examples include fused silica, fumed silica, silica gel, opal, and aerogels. It is used in structural materials, microelectronics (as an electrical insulator), and components in the food and pharmaceutical industries.

The molecule SiO2 has a linear structure like CO2. It is made by combining silicon monoxide (SiO) with oxygen in an argon matrix. Dimeric silica (SiO2)2 is obtained by reacting O2 with dimeric silicon monoxide (Si2O2) separated from the matrix. In dimeric silica, there are two oxygen atoms bridged between silicon atoms, the Si-O-Si angle is 94°, the bond length is 164.6 pm, and the terminal Si-O bond length is 150.2 pm. The Si-O bond length is 148.3 pm, while that of α-quartz is 161 pm. The bond energy is estimated to be 621.7 kJ/mol.

About 95% of the commercial use of silica (sand) occurs in the construction industry, for example in the production of concrete (Portland cement concrete). [

The glass transition temperature of pure SiO2 is about 1475 K [24]. When molten silica SiO2 is cooled rapidly, it does not crystallize but solidifies into glass. Because of this, most ceramic glazes are based on silica.

Silica is used to produce elemental silicon. The process involves carbothermal reduction in an electric arc furnace: [26]

Silica is widely used in semiconductor technology