Why does diamond conduct heat easily

On the other hand, boron arsenide was not expected to be a particularly good thermal conductor and in fact had been estimated — using conventional evaluation criteria — to have a thermal conductivity 10 times smaller than diamond. The team found the calculated thermal conductivity of cubic boron arsenide is remarkably high, more than Watts per meter per Kelvin at room temperature and exceeding that of diamond at higher temperatures, according to Broido and co-authors Tom Reinecke, senior scientist at the Naval Research Laboratory, and Lucas Lindsay, a post-doctoral researcher at NRL who earned his doctorate at BC.

Broido said the team used a recently developed theoretical approach for calculating thermal conductivities, which they had previously tested with many other well-studied materials. Confident in their theoretical approach, the team took a closer look at boron arsenide, whose thermal conductivity has never been measured. Unlike metals, where electrons carry heat, diamond and boron arsenide are electrical insulators. For them, heat is carried by vibrational waves of the constituent atoms, and the collision of these waves with each other creates an intrinsic resistance to heat flow.

So the four outermost electrons, four carbon atoms, are engaged or trapped in the covalent bonds which means that there are no free electrons. So diamond is a good conductor of heat. Diamond normally has a very wide bandgap of 5. Moissanite, a naturally occurring silicon-carbide, is almost as hard as diamond. It is a rare mineral, discovered by the French chemist Henri Moissan in while examining rock samples from a meteor crater located in Canyon Diablo, Arizona.

Butler: In metals, heat is conducted by the electrons, which also conduct charge electricity. Diamond is a giant covalent structure; each valence electron outer shell electron of every carbon atom forms a covalent bond, which means that there are no free electrons. Since electrical conductivity relies on the flow of free electrons, diamond is not a good conductor. There have been a few experimental studies on the thermal conductivity of fullerene and its derivatives.

Recently, fullerene derivatives were found to have ultra-low thermal conductivity, which is even lower than that of C 60 solids. Unlike most electrical insulators, diamond is a good conductor of heat because of the strong covalent bonding and low phonon scattering.

What limits how quickly heat is transferred by this mechanism is phonon scattering. Phonons can scatter on many different things: crystal defects, impurities, crystal boundaries, even other phonons. This is why crystalline substances like diamond tend to have higher thermal conductivity than amorphous ones like glass or polymers as the phonons scatter more when they don't have a nice ordered crystal structure to travel through.

The reason why diamond, in particular, is an especially good thermal conductor even compared to other well-ordered crystals boils down to two factors: the mass of the carbon atoms and the strength of the bonds connecting them.

I don't want to get too much into the details, but briefly, much as a harmonic oscillator has a higher frequency with a stronger spring the strength of the C-C bonds and a lighter mass the C atoms , diamond can support higher energy phonons.

This means that at a given temperature, fewer phonons near the material's limit will be present in diamond than a material with a smaller limit. The details aren't important, but when phonons near the limit interact, they scatter in such a way that the phonons don't travel through the structure.

Because diamond's limit is so high, the probability of this type of scattering is lower. Phonons and electrons travel very well along graphite's graphene sheets, but poorly between them, due to weak inter-layer interactions and the large distance between layers, explaining the anisotropy of its thermal and electronic conductivities.

Metals exhibit both modes of thermal conduction in varying degrees of importance and conduct isotropically since they lack the layered structure of graphite. Sign up to join this community. The best answers are voted up and rise to the top. Select personalised ads.

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