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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?

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    $\begingroup$ 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) $\endgroup$ – Jonathan R Swift Nov 22 '19 at 12:31
  • $\begingroup$ @JonathanRSwift thank's for this nice counter-example $\endgroup$ – Elon Musk Nov 22 '19 at 12:44
  • $\begingroup$ 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). $\endgroup$ – TimWescott Nov 22 '19 at 21:09
  • $\begingroup$ 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. $\endgroup$ – 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).

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  • $\begingroup$ This sounds good. Do you maybe have any source for this, so that I take a closer look? $\endgroup$ – Elon Musk Nov 24 '19 at 1:17
  • $\begingroup$ Either of the two materials science texts by Van Vlack (probably out of print) or the excellent text by Shackelford (more recent). $\endgroup$ – niels nielsen Nov 24 '19 at 1:42

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