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Building a Harder Diamond (SD)
Researchers at the University of Tsukuba used computer calculations to design a new carbon-based material even harder than diamond. This structure, dubbed "pentadiamond" by its creators, may be useful for replacing current synthetic diamonds in difficult cutting manufacturing tasks.
Diamonds, which are made entirely of carbon atoms arranged in a dense lattice, are famous for their unmatched hardness among known materials. However, carbon can form many other stable configurations, called allotropes. These include the familiar graphite in pencil lead, as well as nanomaterials such as carbon nanotubes. The mechanical properties, including hardness, of an allotrope depend mostly on the way its atoms bond with each other. In conventional diamonds, each carbon atom forms a covalent bond with four neighbors. Chemists call carbon atoms like this as having sp3 hybridization. In nanotubes and some other materials, each carbon forms three bonds, called sp2 hybridization.
Now, researchers at the University of Tsukuba have explored what would happen if carbon atoms were arranged in a more complex structure with a mixture of sp3 and sp2 hybridization.
[...] The scientists found that the Young's modulus, a measure of hardness, of pentadiamond was predicted to be almost 1700 GPa, compared with about 1200 GPa for conventional diamond.
Journal Reference:
Yasumaru Fujii, Mina Maruyama, Nguyen Thanh Cuong, Susumu Okada.Pentadiamond: A Hard Carbon Allotrope of a Pentagonal Network of sp2 and sp3 C Atoms (DOI: 10.1103/PhysRevLett.125.016001) (DX)
(Score: 3, Interesting) by EvilSS on Tuesday July 07 2020, @05:56PM
Chemistry is taught with approximations and white lies until you get to courses like physical chemistry, usually taught after all the pre-meds and other majors stop taking chem courses. To quote my p-chem professor: "If we told you the truth before now you would all be history majors. Now you're all too far along to switch easily!" right after explaining that everything we thought we knew about reaction rates was a lie. There were a lot of those moments in that class. Another favorite of mine from that course:"We made calculus a pre-req because if we waited for the math department to get around to teaching you linear algebra and differential equations most of you would be here for 5 years. So you are going to learn it here as we go."
Point being, the reason they don't teach is at first is that they want to work you into the concept, and the orbital models work fine for what you need to know at that level. They even, without saying it, taught you about the probability "clouds" in those courses when they taught you about the "shapes" of the orbitals. Those shapes are based on the probability density plots. If they dumped you into the deep end in a high school course, virtually no one would stand a chance of understanding it, not in the time they have to teach it.