Difference between revisions of "Carbon"

Latest revision as of 10:28, 6 July 2024

See: Gemstone like compound#Carbons versatility

sp³ allotropes:

• Diamond (cubic)
• Lonsdaleite (hexagonal)
• Dialondeite (only accessible via piezomechanosynthesis)
• ...
• O16 carbon – orthorhombic superhard – all-sp3 6 membered rings
• Further less energetically stable all-sp3 allotropes: BC8, BC12, R16

sp² allotropes:

• Graphite (today single cystalline graphite is called HOPG for highly ordered pyrolytic graphite)
  Future: POPMG for "perfectly ordered piezomechanosynthesized graphite.
• Buckyballs (convex curvature; concave from inside) – weak molecular solids
• Nanotubes (no curvature – flat rolled)
• 3D meshes (hyperbolic curvature)
• "penta graphene" (cairo pattern)
• ...

No exactly defined structure:

• DLC diamond like carbon – wikipedia
• Glassy carbon – wikipedia
• Other form of amorphous carbon – wikipedia
• ...

Exotic allotropes:

• ...

Binary compounds:

• Silicon carbide SiC aka moissanite
• Carbon nitrides: beta carbon nitride and cubic gauche carbon nitride

• Titanium carbide TiC aka titanium-khamrabaevite (cubic rock salt structure) Mohs 9-9.5 refractory
• Vanadium carbide VC (vanadium is not too common) vanadium-khamrabaevite
  similar is: NbC and TaC (Nb is not abundant, Ta is extremely rare)
• Zirconium cabide ZrC [1] (same structure but no natural mineral present)
  similar is: HfC (Hf is pretty rare)
• Iron carbide (this here is not cementite!!) iron-khamrabaevite (unknown stability, likely very hard)

• Chromium_carbide (various stoichiometric & structures - may point to useful covalent behavior)
  Cr₃C₂ Tongbaite (refractory, Mohs 9.6; orthorhombic; 6.64g/ccm) Cr is not too abundant
  Cr₂₃C₆
• Molybdenium carbide (de) Mo₂C (insoluble, two modifications α and β) Mo is rather rare
• Tungsten_carbide (hexagonal, Mohs 9) W is rather rare

• Fe₃C, Ni₃C, Co₃C cohenite endmembers (likely rather metallic, Mohs 5.5-6)

• copper and zinc are more electronegative => more covalent behavior => organometallic compounds

• Boron carbide B₄C [2] (boron is not too common)
• Aluminium carbide [3] (reacts with water - releases methane gas CH₄)
• Beryllium carbide Be₂C (very hard but reactive, toxic and rare)
• Magnesium carbide ??? - magnesium acetylide Mg₂C₃ (de wikipedia)
• Calcium carbide CaC₂ (an acetylide - reacts with water - releases ethyne gas C₂H₂)
• TODO: La, Ce, (Li, Na, K)

Way harder than diamond

Macroscopic (pre)tensions can increase resilience but not ultimate tensile strength.
In glass there internal tensions can increase resilience massively.
See Wikipedia on: Prince Rupert's drops
These drops have their tail as weak spot and their shape is pre-given so they are of not much use beside a curiosity for sci-education.
In principle using advanced bottom up manufacturing it might be possible to toughen diamond a lot via internal tensions but leaving no weak spot.

Related

• Diamondoid
• Diamond
• Elements in the same group: Carbon, Silicon, Germanium, Tin, Lead
• Chemical element

• Carbon dioxide
• Carbon dioxide collector

External links

• Wikipedia: Pi bond
• Wikipedia: Orbital hybridisation

• Wikipedia: Carbides and Category:Carbides

• Wikipedia: Graphite_intercalation_compound KC₈
• Wikipedia: Metal_carbido_complex (Transition metal carbides)
• Wikipedia: Metallocarbohedryne