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Exactly what are "ceramics"? I found a lot of similar "definitions" of that term online, e.g. on Wikipedia and here.

These (and other) sources essentially state that ceramics are non-metallic, non-organic materials. And they state the most prominent examples.

But these only seem to be necessary properties. Are there sufficient criteria based on which one can definitely decide whether a certain material is ceramic? Is this list of criteria comprehensive?

Is there even a widely accepted clear definition at all?

Elon Musk
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    Concrete isn't metallic or organic, but I wouldn't call it ceramic (So, I'd say that list of criteria *isn't* comprehensive, although I don't have a better definition to offer without research) – Jonathan R Swift Nov 22 '19 at 12:31
  • @JonathanRSwift thank's for this nice counter-example – Elon Musk Nov 22 '19 at 12:44
  • I think you're supposed to Just Know -- although the concrete example cited by @JonathanRSwift suggests that there needs to be a kiln involved someplace (and not before you mix powder with water). – TimWescott Nov 22 '19 at 21:09
  • A fairly general definition would be "an inorganic compound of a metal and a non-metal". You have to stretch your definitions of "metal" and "inorganic" a bit to include compounds like silicon carbide, of course. – alephzero Nov 22 '19 at 23:29

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The classic (materials science) definition of a ceramic is a compound that is held together by a network of covalent bonds. The fact that these bonds are directional means it is non-metallic- deformation by dislocation-mediated slip does not occur (so no ductility mechanisms are active at ambient temperature) and the substance is a poor conductor of both heat and electricity (since the electrons responsible for holding the material together are immobile).

niels nielsen
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