Siliciumdioxid

Siliciumdioxid, commonly called silica or silicon dioxide, is a chemical compound with the formula SiO2. It forms a dense network covalent structure built from silicon-centered tetrahedra connected through shared oxygen atoms. In nature it exists mainly as crystalline forms such as quartz, cristobalite, and tridymite, and in amorphous forms including silica gel, fume silica, and glassy silica. Quartz is the most common mineral in the Earth's crust and is a major component of sand and many rocks.

Industrial silica is extracted from quartz-rich rocks and refined for a wide range of uses. High-purity silica is essential for electronics as insulating oxide layers on silicon wafers, and it is also a basic raw material for glass, ceramics, cement, and refractories. In addition, various forms of silicas are used as fillers, thickeners, desiccants, or reinforcing agents in consumer products and industrial processes.

Chemically, SiO2 is largely insoluble in water. It dissolves in hot concentrated alkaline solutions to form silicates and in hydrofluoric acid to yield hexafluorosilicic species. It remains stable at high temperatures but can react under strongly basic or acidic conditions with appropriate reagents.

Safety and environmental aspects: silica is generally inert, but inhalation of respirable crystalline silica particles is associated with lung diseases such as silicosis and an increased cancer risk. Proper handling, ventilation, and protective equipment are advised in occupational settings.