. 24/7 Space News .
Large Diamonds Made From Gas Are The Hardest Yet

illustration only
Washington - Feb 27, 2004
Producing a material that is harder than natural diamond has been a goal of materials science for decades. Now a group* headed by scientists at the Carnegie Institution's Geophysical Laboratory in Washington, D.C., has produced gem-sized diamonds that are harder than any other crystals.

Further, the researchers grew these diamonds directly from a gas mixture at a rate that is up to 100 times faster than other methods used to date.

"We believe these results are major breakthroughs in our field," said Chih-shiue Yan, lead author of the study published in the February 20, online Physica Status Solidi. "Not only were the diamonds so hard that they broke the measuring equipment, we were able to grow gem-sized crystals in about a day."

The researches grew the crystals using a special high-growth rate chemical vapor deposition (CVD) process that they developed. They then subjected the crystals to high-pressure, high-temperature treatment to further harden the material.

In the CVD process, hydrogen gas and methane are bombarded with charged particles, or plasma, in a chamber. The plasma prompts a complex chemical reaction that results in a "carbon rain" that falls on a seed crystal in the chamber.

Once on the seed, the carbon atoms arrange themselves in the same crystalline structure as the seed. In this case, the seed was a type 1b synthetic diamond plate. They have grown single crystals of diamonds up to 10 millimeters across and up to 4.5 millimeters in thickness by this method.

The crystals produced by CVD are very tough. "We noticed this when we tried to polish them into brilliant cuts," said Yan. "They were much harder to polish than conventional diamond crystals produced at high pressure and high temperature."

The researchers then subjected the tough CVD crystals to high-temperature and high-pressure conditions. The diamonds were heated to 2000� C and put under pressures between 50,000 and 70,000 times atmospheric pressure (5-7 Gpa) for ten minutes.

This final process resulted in the ultrahard material, which was at least 50% harder than the conventional diamonds as shown by direct measurements carried out in collaboration with scientists at Los Alamos National Laboratory.

"Making diamonds has not been the primary goal of our research," remarked Russell Hemley of Carnegie. "Our group is interested in the behavior of materials at extreme pressures and temperatures.

"We need large, perfect diamond crystals to create new classes of high-pressure devices for our research and decided to explore whether we could make these crystals by CVD processes. We found that we could, and at a very high growth rate.

"This has opened up an entirely new way of producing diamond crystals for a variety of applications, such as the next generation diamond-based electronics devices and cutting tools. Our new finding that the diamonds can be supertough and/or superhard was a surprise and will greatly benefit many of these applications."

CAPTIONS http://www.carnegieinstitution.org/diamond/ Related Links
Carnegie Institution
SpaceDaily
Search SpaceDaily
Subscribe To SpaceDaily Express

Chemistry Puts New Sparkle In Diamonds
Washington - Feb 11, 2004
Diamonds are getting bigger, more colorful and cheaper, thanks to chemistry. A favorite gem at Valentine's Day is getting a makeover with synthetic diamond making processes, according to the Feb. 2 issue of Chemical & Engineering News, the weekly newsmagazine of the American Chemical Society, the world's largest scientific society.



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














The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - 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.