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New Ultrahard Diamond Glass Synthesized
Carnegie's Yingwei Fei and Lin Wang were part of an international research team that synthesized a new ultrahard form of carbon glass with a wealth of potential practical applications for devices and electronics. It is the hardest known glass with the highest thermal conductivity among all glass materials. Their findings are published in Nature.
[...] Because of its extremely high melting point, it's impossible to use diamond as the starting point to synthesize diamond-like glass. However, the research team, led by Jilin University's Bingbing Liu and Mingguang Yao—a former Carnegie visiting scholar—made their breakthrough by using a form of carbon composed of 60 molecules arranged to form a hollow ball. Informally called a buckyball, this Nobel Prize-winning material was heated just enough to collapse its soccer-ball-like structure to induce disorder before turning the carbon to crystalline diamond under pressure.
The team used a large-volume multi-anvil press to synthesize the diamond-like glass. The glass is sufficient large for characterization. Its properties were confirmed using a variety of advanced, high-resolution techniques for probing atomic structure.
Journal Reference:
Yuchen Shang, Zhaodong Liu, Jiajun Dong, et al. Ultrahard bulk amorphous carbon from collapsed fullerene, Nature (DOI: 10.1038/s41586-021-03882-9)
(Score: 2) by VLM on Saturday November 27 2021, @09:28PM (1 child)
The first question, this link very handwavy implies you can't have a glassy substance that's not at least somewhat of an insulator. And this being in the category of glassy material, and the link implying glasses are not classic conductors...
https://en.wikipedia.org/wiki/Glass_transition#Electronic_structure [wikipedia.org]
As with plastics and stuff "in practice" you might add enough powdered copper to the substance to make it somewhat conductive, and nothing is a perfect insulator, etc, but very handwavy it seems like the physics of why it has no crystalline structure as a super cooled liquid would mostly imply its impossible to make a classic conductor or semiconductor out of it.
The second question, there are plenty of glasses that are not transparent to visible light. You can't see thru tire rubber even if they don't add carbon to it. Some glasses like PMMA (aka "plexiglass") are very transparent to visible light. So there's no theoretical reason it couldn't be transparent; but most things are not, so I would not bet on it. Note that it could be like germanium metal which is transparent to IR light but not visible light, not like Ge in the sense of being a metal (its a glass) but like Ge in the sense of having weird transmission bands that may not be in visible light range.
(Score: 2) by VLM on Saturday November 27 2021, @09:44PM
I'd rephrase that, after thinking about it, to something like a glass has to be a poor electrical conductor. If the mean free path were long enough to be a metal conductor, that would imply the glass is a crystalline metal, when the whole point of a glass is its solid but not crystalline, so the MFP has to be really short like shorter than atomic spacing...
Also it turns out its visually transparent, missed literally one word in the abstract, whoops. I suppose if the whole point is you're sqoooshing C60 into a glassy sea of sp3 bonds, and diamonds being crystalline sp3 bonds, and diamonds being visually transparent, its not too surprising.