Space diamonds reveal supernova origins

Feb 15, 2012 By Brian Jacobsmeyer
Although diamonds are rare on Earth, scientists believe that minuscule "nanodiamonds" abound in space. Credit: ISNS/ jtaylor14368 & Swamibu via flickr

Space diamonds may now be an astrophysicist's best friend.

For years, scientists have found DNA-sized in meteorites on Earth. New research suggests that these diamonds spring from violent cosmic collisions, which may help scientists unravel mysteries surrounding exploding stars -- the birthplaces of that predate our solar system.

Although diamonds are rare on Earth, scientists believe that minuscule "nanodiamonds" abound in space. Researchers have been trying to decipher the origin of these enigmatic minerals for decades.

On Earth, traditional diamonds are forged deep underground under intense heat and pressure over the course of billions of years. Space diamonds, however, can form in a millionth of a millionth of a second according to new research appearing in the journal Physical Review Letters.

"The transformation is quite astonishing," said Nigel Marks, a materials scientist at Curtin University in Perth, Australia, and coauthor of the research paper. "I never would have imagined this was possible."

Marks simulated collisions on his computer and found that diamond formation didn't require blistering temperatures or crushing pressures. Instead, in simulations, diamonds formed when carbon-containing smashed together at speeds exceeding 10,000 miles per hour.

Within the original grains, spherical fullerenes -- soccer-ball-shaped -- enclose one another like Russian nesting dolls. Together, these concentric molecules compose layered carbon "onions."

When the carbon onions slammed into each other, the molecules flattened, squeezed and linked together. During this process, the onions rearranged themselves into hexagonal shapes indicative of diamond structure.

If they collided at high enough speeds, then the carbon onions were destroyed. And if the particles weren't moving fast enough, then the carbon onions did not complete the transition to diamonds. The researchers found that the narrow speed range that facilitates nanodiamond formation is common in space.

"They found that there's sort of a sweet spot," said Andrew Davis, a geochemist at the University of Chicago, who was not affiliated with the research. "If you can do it just right, you can make nanodiamonds. That was interesting."

With this new model for nanodiamond formation, scientists hope to unlock some of the secrets these diamonds contain. Until now, scientists have only extracted limited information from nanodiamonds partly because they didn't have a suitable theory for their formation, said Marks.

"There's a huge message embedded in the nanodiamond," said Marks. "[Researchers] just couldn't figure out what it was."

Forms of elements such as gaseous xenon with different amounts of neutrons have been found inside meteorite nanodiamonds. Called isotopes, these variants of the same elements convey information about exploding stars from earlier in the universe's history. Different ratios of isotopes are produced in different nuclear reactions, giving scientists clues as to what types of dying stars gave birth to these isotopes.

According to Marks and his team, xenon is likely incorporated into carbon onions before they collide and produce nanodiamonds. By better understanding where these embedded isotopes originate, scientists can glean new information about the death of stars and the origins of our solar system.

Several competing theories, however, suggest nanodiamonds were formed differently than Marks' research indicates. For instance, some scientists think that shock waves from may have created nanodiamonds. Intense pressure and heat from the shock wave could also have led to the implantation of noble gases like xenon.

But all theories put forth so far have been hampered by limited experimental evidence. Because nanodiamonds are so small, it's been extremely difficult to look at them individually.

To help resolve this issue, Marks and his colleagues hope to translate their simulations into lab experiments in the coming months. By creating nanodiamonds on Earth, the research team could produce large enough samples to analyze.

The samples could also be used for biomedical and industrial applications.

Manufacturers already create similarly sized nanodiamonds to use as drug markers or dry lubricants. Current methods require extremely high temperatures, though, limiting the types of materials that can be coated. Using the method put forth by Marks and his team, manufacturers could create coatings for materials that melt relatively easily, such as steel.

High speeds on such a small scale can be tricky, however.

"I think it's probably not trivial to accelerate these grains to 5 kilometers per second," said Davis. "That's a hard thing to do in a lab."

Nonetheless, Marks hopes that his simulations will guide future experiments.

"Now that we know this possibility exists, we want to go on and figure out what you can do with it," said Davis.

Explore further: Physicists advance understanding of transition metal oxides used in electronics

Provided by Inside Science News Service

4.8 /5 (9 votes)

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User comments : 9

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Sanescience
3.7 / 5 (3) Feb 15, 2012
There are voices everywhere, you just need to know how to listen.
that_guy
5 / 5 (1) Feb 15, 2012
I think this article got me more interested in carbon onions than nano daimonds.

What would "Carbon onions" be like if you created them at a macro size?
huntingsthompson
1 / 5 (1) Feb 15, 2012
Is this why it would be more worthwhile to visit an asteroid? Valuable, cosmologically produced materials that could be harvested in low gravity environments; it would seem like a better alternative rather than launching materials from Earth...
antialias_physorg
4 / 5 (4) Feb 16, 2012
What would "Carbon onions" be like if you created them at a macro size?

Lumps of graphite which break along clean lines would be my guess.

Is this why it would be more worthwhile to visit an asteroid?

I don't know. Diamonds aren't exactly spectacularly precious on Earth (other than through sheer hype - much like tulips in the 1630s).
If we find asteroids made up of 99% Lithium or one of the rare earths then that would be another story.
panostrm
1 / 5 (1) Feb 16, 2012
Well,if scientists will be able to create nanodiamonds in the future,maybe an allternative use they could possibly have,is in creating invisible cloak,by manipulating light according to diamonds structure!!..Just thinking..!
that_guy
5 / 5 (1) Feb 16, 2012
@Huntingsthompson: We already can make real gem quality and industrial quality diamonds on the macro and micro scale. Why would we need or want to go through the huge expense of harvesting mostly useless nano diamonds from space for any reason other than science.

@panostrm - Scientists can easily create nano diamonds using a variety of processes, such as - methane vapor deposition.

I'm not going to explain in detail about your invisibility cloak. Just no - Diamonds have little to do with the challenge of making one. It's a question of negative refraction that requires a metamaterial that cannot be created with just one element.

Wikipedia is great for finding out things when you wonder.
Torbjorn_Larsson_OM
not rated yet Feb 20, 2012
Can I have 'tatoes with those cooked onions, please?

@ antalias:

Except that rare earth's, like diamonds perhaps, aren't that rare either, just in relation to everyday metals (iron, aluminum).

Diamonds _should_ be rare btw, since they only get to the surface when formed in special magma flows. To add to that I think that type of magma is less prevalent today, due to the biosphere oxidation of the crust.
antialias_physorg
not rated yet Feb 20, 2012
That's why I said "made up of 99% Lithium or one of the rare earths".

Rare earths are just too diluted in common soils to make their extraction worthwhile. if we'd find an asteroid of, say, several hundred meters in diameter where such costly extraction isn't needed, because the stuff is highly enriched, then mining it might actually be economically viable.
that_guy
not rated yet Feb 21, 2012
Except that rare earth's, like diamonds perhaps, aren't that rare either, just in relation to everyday metals (iron, aluminum).

The earth has plenty of almost all elements. It's just that to get substantial concentrations of certain elements, you may have to mine 3000 miles down.

Gold for example. All the gold ever mined could fit in a 20 meter cube. platinum. iridium. Rare earth metals, etc.

They may not be "rare" but minable concentrations are rare since most has differentiated into the lower layers of the earth. On the surface, geology and weather have dispersed crustal concentrations.

Asteroids sport areas of higher ore concentration and less internal differentiation, making them very intriguing areas of mining interest.

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