Here "metal" and "metallic" are used in a loose sense, which is not useful in practice.
In careful speaking, since the 18th century there has been a clear distinction, between the words "metal" and "semimetal", though sadly even a lot of chemists or metallurgists use these words incorrectly.
Both metals and semimetals are materials that have free electrons, so they share all the properties caused by free electrons, e.g. high electrical and thermal conductivities and metallic luster.
The difference between metals and semimetals is in their crystal structure.
Metals have crystal structures with high coordination numbers, which makes them ductile and malleable, i.e. susceptible of plastic deformation.
On the other hand, semimetals have crystal structures with low coordination numbers, which makes them fragile, so they cannot be shaped by plastic deformation.
A typical semimetal is graphite, i.e. the normal state of carbon, which is a good electrical and thermal conductor, but you cannot make a wire of it, because it will break.
Because of the difference between metals and semimetals, when a better conductor is found it matters a lot whether it is a metal or a semimetal.
This tantalum nitride is a semimetal, like graphite, not a metal like copper. Thus, regardless of its high cost (tantalum is one of the least abundant and most expensive metals), it could never replace copper in applications where you must make parts by plastic deformation or they must be flexible when used.
Unlike in TFA, in the 2021 research paper already mentioned by another poster, where this material was first reported, the authors use a correct terminology, so their paper abstract says: "This study provides new insight into heat conduction in semimetallic solids and extends the search for high-K materials into the realms of semimetals and noncubic crystal structures."
Besides a few chemical elements that are semimetals when pure, e.g. graphite, antimony and bismuth, most carbides and nitrides of the transition metals are also semimetals. Many borides and silicides are semimetals too. Some silicides are used for certain "metal" layers in integrated circuits, where the fact that they are not ductile does not matter, because they are attached upon a rigid semiconductor crystal. Similarly, this kind of tantalum nitride could potentially be used for some kind of heat spreader in a power semiconductor device, where a very small amount of it could be sufficient, and neither its fragility nor its high cost would matter. However, the application should benefit from its electrical conductivity, because cheaper non-conductive materials for heat spreaders exist, e.g. silicon carbide, aluminum nitride or beryllia.
> In the form of tantalum nitride that Hu and his colleagues studied, the atomic structure of the crystal lattice lets phonons travel unusually long distances with minimal interference.
Sort of like a thermal (phonon) superconductor.. Maybe there's a true thermal superconductor out there to be discovered...
Previously, when they first reported the material in 2021, I think? https://feng.mech.utah.edu/wp-content/uploads/sites/152/2022...
Still only half the thermal conductivity of diamond. But pretty awesome nonetheless! I hope it's easy to make.
Can we make heat sink out of synthetic diamonds?
As another poster has said, heatsinks made of synthetic diamonds have been used for a long time in the most demanding applications.
However, until now their use has been limited by very high cost and by small maximum sizes.
Thus you will not see them in consumer applications, for now.
Yes, that is a thing.
Also fabricating integrated circuits on a diamond substrate.
Here "metal" and "metallic" are used in a loose sense, which is not useful in practice.
In careful speaking, since the 18th century there has been a clear distinction, between the words "metal" and "semimetal", though sadly even a lot of chemists or metallurgists use these words incorrectly.
Both metals and semimetals are materials that have free electrons, so they share all the properties caused by free electrons, e.g. high electrical and thermal conductivities and metallic luster.
The difference between metals and semimetals is in their crystal structure.
Metals have crystal structures with high coordination numbers, which makes them ductile and malleable, i.e. susceptible of plastic deformation.
On the other hand, semimetals have crystal structures with low coordination numbers, which makes them fragile, so they cannot be shaped by plastic deformation.
A typical semimetal is graphite, i.e. the normal state of carbon, which is a good electrical and thermal conductor, but you cannot make a wire of it, because it will break.
Because of the difference between metals and semimetals, when a better conductor is found it matters a lot whether it is a metal or a semimetal.
This tantalum nitride is a semimetal, like graphite, not a metal like copper. Thus, regardless of its high cost (tantalum is one of the least abundant and most expensive metals), it could never replace copper in applications where you must make parts by plastic deformation or they must be flexible when used.
Unlike in TFA, in the 2021 research paper already mentioned by another poster, where this material was first reported, the authors use a correct terminology, so their paper abstract says: "This study provides new insight into heat conduction in semimetallic solids and extends the search for high-K materials into the realms of semimetals and noncubic crystal structures."
Besides a few chemical elements that are semimetals when pure, e.g. graphite, antimony and bismuth, most carbides and nitrides of the transition metals are also semimetals. Many borides and silicides are semimetals too. Some silicides are used for certain "metal" layers in integrated circuits, where the fact that they are not ductile does not matter, because they are attached upon a rigid semiconductor crystal. Similarly, this kind of tantalum nitride could potentially be used for some kind of heat spreader in a power semiconductor device, where a very small amount of it could be sufficient, and neither its fragility nor its high cost would matter. However, the application should benefit from its electrical conductivity, because cheaper non-conductive materials for heat spreaders exist, e.g. silicon carbide, aluminum nitride or beryllia.
"a metallic material called θ-phase tantalum nitride"
> In the form of tantalum nitride that Hu and his colleagues studied, the atomic structure of the crystal lattice lets phonons travel unusually long distances with minimal interference.
Sort of like a thermal (phonon) superconductor.. Maybe there's a true thermal superconductor out there to be discovered...
"Maybe there's a true thermal superconductor out there to be discovered..."
it's called a vacume, and honestly I believe that for heat, thats it, given it's role in physics....
Vacuum? It’s a terrible conductor. Closer to a perfect insulator.