kiseloxid

Kiseloxid, or silicon oxide, refers to chemical compounds composed of silicon and oxygen. The most common member is silicon dioxide with the formula SiO2. Silicon dioxide occurs in several crystalline forms, including quartz, cristobalite and tridymite, as well as in amorphous forms such as fused silica, silica gel and glass. It is one of the most abundant compounds in the Earth's crust.

Natural occurrence is extensive. Quartz is widespread in rocks and sands, and silica in various forms supports many geological and biological processes. Opal and diatoms provide notable natural examples of hydrated or biogenic silica. Silica also occurs in groundwater and soils, where its solubility is influenced by pH and temperature.

Key properties include high hardness (Mohs scale about 7 for quartz), a very high melting point (about 1713°C for crystalline SiO2), and strong chemical stability. Silicon dioxide is a poor conductor of electricity and is transparent to visible light, with a refractive index around 1.46 to 1.54 depending on form. It is largely insoluble in water, although soluble in strong alkalis at high temperatures. SiO2 forms a wide network structure in crystalline forms and an extensive network in amorphous glassy forms, which affects its mechanical and optical properties.

Uses and production are broad. Industrially, SiO2 is a primary raw material for glass and ceramics, cement, and various fillers. In electronics and optics, silicon dioxide serves as an insulating layer, a component of glass for fiber optics, and as a substrate in some sensors and microdevices. Silica gels and silicates have applications in desiccants, chromatography and catalysis. Health and safety considerations focus on respirable crystalline silica, which can pose a risk to lung health with prolonged exposure.