Subscribe free to our newsletters via your
. 24/7 Space News .




DEEP IMPACT
Asteroid impacts on Earth make structurally bizarre diamonds
by Staff Writers
Phoenix AZ (SPX) Nov 25, 2014


Diamond grains from the Canyon Diablo meteorite. The tick marks are spaced one-fifth of a millimeter (200 microns) apart. Image courtesy Arizona State University/Laurence Garvie.

Scientists have argued for half a century about the existence of a form of diamond called lonsdaleite, which is associated with impacts by meteorites and asteroids. A group of scientists based mostly at Arizona State University now show that what has been called lonsdaleite is in fact a structurally disordered form of ordinary diamond.

The scientists' report is published in Nature Communications, Nov. 20, by Peter Nemeth, a former ASU visiting researcher (now with the Research Centre of Natural Sciences of the Hungarian Academy of Sciences), together with ASU's Laurence Garvie, Toshihiro Aoki and Peter Buseck, plus Natalia Dubrovinskaia and Leonid Dubrovinsky from the University of Bayreuth in Germany. Buseck and Garvie are with ASU's School of Earth and Space Exploration, while Aoki is with ASU's LeRoy Eyring Center for Solid State Science.

"So-called lonsdaleite is actually the long-familiar cubic form of diamond, but it's full of defects," says Peter Nemeth. These can occur, he explains, due to shock metamorphism, plastic deformation or unequilibrated crystal growth.

The lonsdaleite story began almost 50 years ago. Scientists reported that a large meteorite, called Canyon Diablo after the crater it formed on impact in northern Arizona, contained a new form of diamond with a hexagonal structure. They described it as an impact-related mineral and called it lonsdaleite, after Dame Kathleen Lonsdale, a famous crystallographer.

Since then, "lonsdaleite" has been widely used by scientists as an indicator of ancient asteroidal impacts on Earth, including those linked to mass extinctions. In addition, it has been thought to have mechanical properties superior to ordinary diamond, giving it high potential industrial significance.

All this focused much interest on the mineral, although pure crystals of it, even tiny ones, have never been found or synthesized. That posed a long-standing puzzle.

The ASU scientists approached the question by re-examining Canyon Diablo diamonds and investigating laboratory samples prepared under conditions in which lonsdaleite has been reported.

Using the advanced electron microscopes in ASU's Center for Solid State Science, the team discovered, both in the Canyon Diablo and the synthetic samples, new types of diamond twins and nanometer-scale structural complexity. These give rise to features attributed to lonsdaleite.

"Most crystals have regular repeating structures, much like the bricks in a well-built wall," says Peter Buseck. However, interruptions can occur in the regularity, and these are called defects.

"Defects are intermixed with the normal diamond structure, just as if the wall had an occasional half-brick or longer brick or row of bricks that's slightly displaced to one side or another."

The outcome of the new work is that so-called lonsdaleite is the same as the regular cubic form of diamond, but it has been subjected to shock or pressure that caused defects within the crystal structure.

One consequence of the new work is that many scientific studies based on the presumption that lonsdaleite is a separate type of diamond need to be re-examined. The study implies that both shock and static compression can produce an intensely defective diamond structure.

The new discovery also suggests that the observed structural complexity of the Canyon Diablo diamond results in interesting mechanical properties. It could be a candidate for a product with exceptional hardness.

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
Arizona State University
Asteroid and Comet Impact Danger To Earth - News and Science






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





DEEP IMPACT
New Map Shows Frequency of Small Asteroid Impacts
Pasadena CA (JPL) Nov 17, 2014
A map released by NASA's Near Earth Object (NEO) Program reveals that small asteroids frequently enter and disintegrate in the Earth's atmosphere with random distribution around the globe. Released to the scientific community, the map visualizes data gathered by U.S. government sensors from 1994 to 2013. The data indicate that Earth's atmosphere was impacted by small asteroids, resulting i ... read more


DEEP IMPACT
Young Volcanoes on the Moon

U.K. group to crowd-source funding for moon mission

After Mars, India space chief aims for the moon

China examines the three stages of lunar test run

DEEP IMPACT
Within Rover's Reach at Mars Target Area 'Alexander Hills'

Mars Exploration Program Director Named

Second Time Through, Mars Rover Examines Chosen Rocks

Mars was warm enough for flowing water, but only briefly

DEEP IMPACT
The International Space Station officially has an espresso machine

Astronauts to get 'ISSpresso' coffee machine

Tencent looks to the final travel frontier

ESA Commissions Airbus As contractor For Orion Service Module

DEEP IMPACT
China expects to introduce space law around 2020

China launches new remote sensing satellite

China publishes Earth, Moon photos taken by lunar orbiter

China plans to launch about 120 applied satellites

DEEP IMPACT
Soyuz docks at Space Station; Expedition 42 joins crew

Italy's first female astronaut heads to ISS in Russian craft

Space station gets zero-gravity 3-D printer

NASA Commercial Crew Partners Continue System Advancements

DEEP IMPACT
Elon Musk unveils 'drone ship' and 'x-wing' fins for rockets via Twitter

Russian Rocket Supply for Satellites Launches Continues

China launches Yaogan-24 remote sensing satellite

Soyuz Installed at Baikonur, Expected to Launch Wednesday

DEEP IMPACT
Hot, Super-Earths Help Track Water-Rich Atmospheres

How to estimate the magnetic field of an exoplanet?

Follow the Dust to Find Planets

NASA's TESS mission cleared for next development phase

DEEP IMPACT
U.S. supplies Ukraine with counter-mortar radar systems

Versatile bonding for lightweight components

Cloaking device hides across continuous range of angles

A new approach to the delivery of satellites to orbit




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.