Harder-Than-Diamond Natural Carbon Crystals Found 250
HikingStick tips a piece from the science desk at MSNBC.com about a new, naturally occurring form of carbon found in a meteorite fragment. "Researchers were polishing a slice of the carbon-rich Havero meteorite that fell to Earth in Finland in 1971. When they then studied the polished surface they discovered carbon-loaded spots that were raised well above the rest of the surface — suggesting that these areas were harder than the diamonds used in the polishing paste... [G]raphite layers were shocked and heated enough to create bonds between the layers — which is exactly how humans manufacture diamonds... [The research] team took the next step and put the diamond-resistant crystals under the scrutiny of some very rigorous mineralogical analyzing instruments to learn how its atoms are lined up. That allowed them to confirm that they had, indeed, found a new 'phase' or polymorph of crystalline carbon as well as a type of diamond that had been predicted to exist decades ago, but had never been found in nature until now."
Re:One thing I don't get... (Score:5, Informative)
The very end of the article suggests that they are harder than regular naturally occurring diamonds.
However, there is no way at the present to compare them to the artificial ultra-hard diamonds known as lonsdaleite and boron nitride, Ferroir said.
Re:I don't know about you (Score:5, Informative)
...do you think that the meteorite was made by magicians?
Space is natural too.
Re:One thing I don't get... (Score:5, Informative)
However, there is no way at the present to compare them to the artificial ultra-hard diamonds known as lonsdaleite and boron nitride, Ferroir said.
Boron nitride is not diamond at all, and lonsdaleite is described by Wikipedia as an allotrope of carbon that is found in meteorites and is harder than diamonds. Perhaps these people have just re-discovered something that was already known.
Re:One thing I don't get... (Score:4, Informative)
... not harder than natural diamonds.
That is because what they are (or should be) talking about is not hardness, but mechanical strength. Black diamonds are not harder, but because they consist of microscopic crystals, they don't have the convenient break lines of monocrystals, and therefore are more difficult to process. See:
http://www.sciencedaily.com/videos/2007/0612-mystery_diamonds.htm [sciencedaily.com]
Lonsdaleite (Score:5, Informative)
Re:One thing I don't get... (Score:5, Informative)
They've got an odd definition of "diamond" there: boron nitride has no carbon in it. It's a chemical analogue of diamond, in that you turn half the C atoms (atomic number 6) into B (atomic number 5) and the others into N (atomic number 7). B-N compounds are fun analogues of C compounds but it's a bit of a stretch.
Re:Mohs Scale of Hardness (Score:2, Informative)
Another way to make harder than normal diamonds (Score:4, Informative)
Londsaleite or not? (Score:2, Informative)
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Materials Science [feeddistiller.com] Feed @ Feed Distiller [feeddistiller.com]
Re:What about bb's? (Score:5, Informative)
Re:Mohs Scale of Hardness (Score:4, Informative)
The Mohs hardness is ordinal, not linear, so until unless this item is added to the scale it will have an undefined Mohs hardness. Actual engineers use Brinell hardness or something similar.
Re:Lonsdaleite (Score:3, Informative)
It probably *COULD* hold more *for a time*. But the question is what is the failure load in all directions? Buildings/bridges/dams/etc are not static structures. They 'move around'; be it wind or snow or people just walking around on it. They are designed to 'float' in the dirt. Ever been in a house that 'settled' a little? The house didnt collapse it just bent a little. That is part of the design. Buildings/bridges that do not flex break, and quite spectacularly.
This is an example of a design that had too much sway in it (the wind didnt pass over the roadway correctly). But notice it DID sway...
http://www.youtube.com/watch?v=j-zczJXSxnw&feature=fvw [youtube.com]
My point? You can design in too little sway and it will crack your building in half when everything around it fails. Or you can design in too much sway and it will fly apart.
Could this have applications? Absolutely. However, with your diamond I-beam how do I rivet it together as we do not grow buildings on site? Rivets work by melting two large chunks of steel with a smaller one with a small weld. There are a few challenges you need to get past with construction.
For example concrete is also harder than steel. It is however extremely brittle which is why roadways and building structures are reinforced with something 'hard' but flexible. I could make an I-beam of concrete (and people do this) and get similar strength out of it but I would be a fool not to reinforce it in some way. It would shatter within months of use.
I may not be an architect but I studied many years to be one. And I didnt want to be a structural engineer.
Journal Article (Score:3, Informative)
For those that are interested in considering scientific paper without the media filter:
Ferroir, Tristan, Leonid Dubrovinsky, Ahmed El Goresy, Alexandre Simionovici, Tomoki Nakamura, and Philippe Gillet. 2010. Carbon polymorphism in shocked meteorites: Evidence for new natural ultrahard phases. Earth and Planetary Science Letters 290, no. 1-2: 150-154. doi:10.1016/j.epsl.2009.12.015. http://linkinghub.elsevier.com/retrieve/pii/S0012821X09007389 [elsevier.com].
I sure wish that secondary sources properly cited primary sources, even if they are only interviewing the main scientist involved. Giving the journal name and date as Discovery News did is a good step, though.
link to orign article (Score:4, Informative)
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V61-4Y4XCTH-3&_user=10&_coverDate=02%2F15%2F2010&_rdoc=18&_fmt=high&_orig=browse&_srch=doc-info(%23toc%235801%232010%23997099998%231609118%23FLA%23display%23Volume)&_cdi=5801&_sort=d&_docanchor=&_ct=26&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=ae24ceb289eae1dcc9bc6870f3192dc2 [sciencedirect.com]
And this is the abstract A slice of the Haverö meteorite which belongs to the ureilite class known to contain graphite and diamond was cut and then polished as a thin section using a diamond paste. We identified two carbonaceous areas which were standing out by more than 10 m in relief over the surface of the silicate matrix suggesting that the carbonaceous phases were not easily polishable by a diamond paste and would therefore imply larger polishing hardness. These areas were investigated by reflected light microscopy, high-resolution Field Emission SEM (FESEM), energy-dispersive X-ray (EDX) analysis, Raman spectroscopy, and were subsequently extracted for in situ synchrotron microbeam X-ray fluorescence (XRF), imaging and X-ray diffraction (XRD). We report here the natural occurrences of one new ultrahard rhombohedral carbon polymorph of the R3m space group which structure is very close to diamond but with a partial occupancy of some of the carbon sites. We also report the natural occurrence of the theoretically predicted 21R diamond polytype with lattice parameters very close to what has been modelized. These findings are of great interests for better understanding the world of carbon polymorphs and diamond polytypes giving new natural materials to investigate. These natural samples demonstrate that the carbon system is even more complex than what is currently thought based on ab initio static lattice calculations and high-pressure experiments since this new ultrahard polymorph has never been predicted nor synthesized.
Re:Another way to make harder than normal diamonds (Score:1, Informative)
The difference in zero-point energy between two C-12 atoms and two C-14 atoms is:
E14/E12 = (h*v14)*(0+0.5)/( (h*v12)*(0+0.5) ) = v14/v12 = sqrt( mu12/mu14 )
where "v" is vibrational frequency, and "mu" is reduced mass = mA*mB/(mA+mB) (I'm skipping some steps...). This gives a difference of about 7%. Not huge, but it is measurable.
It's also worth noting that isotopically-pure diamond will have higher thermal conduction. Having different isotopes acts as (weak) crystal defects, which scatters phonons (sound waves) and disrupts thermal conduction. So isotopically pure diamond has measurably better thermal characteristics.
So, getting isotopcially pure diamond is a way to make it stronger and higher-performance... but really the gains are small compared to the considerable effort required to purify.
Re:One thing I don't get... (Score:5, Informative)
Re:Lonsdaleite (Score:3, Informative)
For example concrete is also harder than steel. It is however extremely brittle which is why roadways and building structures are reinforced with something 'hard' but flexible.
That’s why they created pre-stressed concrete. The key is to keep the concrete under compression at all times and transfer all tensile forces to a different structural component that performs well under tension.