Silicon carbide
In addition to silicon dioxide, silicon carbide SiC is the most important silicon compound. Due to the chemical similarity of the partners silicon and carbon with 4 valence electrons each, the compound crystallises to form a tetrahedra diamond crystal structure. The material is often used as an abrasive for its high hardness. Though it has semiconductor properties of its own, it is rather used as a substrate for other semiconductor materials due to its low thermal expansion.