Silicon carbide, , is a compound of silicon and carbon with a strongly bonded extended structure. It is both a hard ceramic and a wide-band gap semiconductor, illustrating how one material can be useful for mechanical and electronic reasons.
Its local tetrahedral bonding can occur with different stacking sequences, giving multiple polytypes. These share composition while differing in long-range order and electronic properties. Consequently a statement about a silicon-carbide band gap, crystal symmetry or device behaviour must specify the structural form. An empirical formula alone does not determine a solid's full microscopic structure.
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