Carnegie Institution new approach to making diamonds

Jun 06, 2004 4 Replies
A

I know that this has been posted to sci.materials before, but this sure is interesting!



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The researchers took CVD grown diamond, subjected it to 70kBar and



2000C for a few minutes, and out comes a flawless gem quality stone.

Carnegies's process sounds a little like the sintered diamond approach described in this document

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The authors of the pdf believe that diamond at 60kBar and 2000C assume some plasticity.



These two processes remind me of glacial ice forming from compacting snow. In the CVD case, are the tiny voids between crystals geting mashed out? How does this result in perfect cleavage? Sintered diamond doesn't have perfect cleavage to be sure, but I wonder if a sintering process applied with 300kBar and 4000C could make gem crystals..


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M

If you've got two crystals fusing together under pressure, surely they won't have their crystal axes 100% aligned, therefore there must be a transition region at the borders between fused crystals in the solid. Won't this transition region have some optical properties of its own, such as lower density hence lower index of refraction? Therefore, it won't be gem-quality, or at least not very good gem quality. Maybe good enough for the wedding rings that trailer trash buys at the Wal-Mart in Klamath Falls, but not anything that would rate high enough to be used in the serious jewelry trade.

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H

Hmmm, something seems very wrong here. 50% harder than natural diamond!(and that they say is a mimimum.)

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A

I cant wait to see the carbon 13 version. Seriously, how can they claim a 50% improvement in hardness when it's basically the same molecule that natural diamond is. Or is it?

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H

They are big on hype, but not on detail. It looks like bullshit, and until they demonstate otherwise it will remain so.

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