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TOPIC: The Diamond Age


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Nanodiamond matrix
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Title: Synthesis and characterisation of a nanocrystalline diamond aerogel
Authors: Peter J. Pauzauskie, Jonathan C. Crowhurst, Marcus A. Worsley, Ted A. Laurence, A. L. David Kilcoyne, Yinmin Wang,  Trevor M. Willey, Kenneth S. Visbeck, Sirine C. Fakra, William J. Evans, Joseph M. Zaug, and Joe H. Satcher, Jr.

Aerogel materials have myriad scientific and technological applications due to their large intrinsic surface areas and ultralow densities. However, creating a nanodiamond aerogel matrix has remained an outstanding and intriguing challenge. Here we report the high-pressure, high-temperature synthesis of a diamond aerogel from an amorphous carbon aerogel precursor using a laser-heated diamond anvil cell. Neon is used as a chemically inert, near-hydrostatic pressure medium that prevents collapse of the aerogel under pressure by conformally filling the aerogel's void volume. Electron and X-ray spectromicroscopy confirm the aerogel morphology and composition of the nanodiamond matrix. Time-resolved photoluminescence measurements of recovered material reveal the formation of both nitrogen- and silicon- vacancy point-defects, suggesting a broad range of applications for this nanocrystalline diamond aerogel.

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Diamonds
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Mystery of diamond's soft side solved

A German research has decoded the atomic mechanism behind diamond grinding, explaining how the hardest known material in the world can be machined.
A team of researchers at the Fraunhofer Institute for Mechanics of Materials IWM in Freiburg, Germany, said their findings would have broader implications for understanding friction and wear on materials.

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Diamond laser
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Diamond is best known for being a prized gem and the hardest cutting element available. Now, thanks to research, it is also proving to be a super efficient laser material.
Richard Mildren, associate professor, and his colleagues at the Macquarie University Photonics Research Centre discovered in late 2008 that it was possible to generate a coherent laser beam from synthetic diamond.

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Diamonds
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Scientists have found crystals in a meteorite that are even harder than diamonds.
According to a report in Discovery News, the finding was made by Tristan Ferroir and his team from the Universite de Lyon in France.
A closer look with an array of instruments revealed two totally new kinds of naturally occurring carbon, which are harder than the diamonds formed inside the Earth.

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RE: The Diamond Age
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Diamond Oceans Possible on Uranus, Neptune

Oceans of liquid diamond, filled with solid diamond icebergs, could be floating on Neptune and Uranus, according to a recent article in the journal Nature Physics.
The research, based on first detailed measurements of the melting point of diamond, found diamond behaves like water during freezing and melting, with solid forms floating atop liquid forms. The surprising revelation gives scientists a new understanding about diamonds and some of the most distant planets in our solar system.

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Title: Melting temperature of diamond at ultrahigh pressure
Authors: J. H. Eggert, D. G. Hicks, P. M. Celliers, D. K. Bradley, R. S. McWilliams, R. Jeanloz, J. E. Miller, T. R. Boehly & G. W. Collins

Since Ross proposed that there might be 'diamonds in the sky' in 1981, the idea of significant quantities of pure carbon existing in giant planets such as Uranus and Neptune has gained both experimental and theoretical support. It is now accepted that the high-pressure, high-temperature behaviour of carbon is essential to predicting the evolution and structure of such planets. Still, one of the most defining of thermal properties for diamond, the melting temperature, has never been directly measured. This is perhaps understandable, given that diamond is thermodynamically unstable, converting to graphite before melting at ambient pressure, and tightly bonded, being the strongest bulk material known. Shock-compression experiments on diamond reported here reveal the melting temperature of carbon at pressures of 0.6 - 1.1 TPa (6 - 11 Mbar), and show that crystalline diamond can be stable deep inside giant planets such as Uranus and Neptune. The data indicate that diamond melts to a denser, metallic fluid - with the melting curve showing a negative Clapeyron slope - between 0.60 and 1.05 TPa, in good agreement with predictions of first-principles calculations. Temperature data at still higher pressures suggest diamond melts to a complex fluid state, which dissociates at shock pressures between 1.1 and 2.5 TPa (11 - 25 Mbar) as the temperatures increase above 50,000 K.

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Natural diamonds are forged in the high temperatures and crushing pressures of the earths interior. But to make nanoscale diamond crystals, researchers have used their own tricks, including recipes involving carbon nanotubes. Now a team explains at the atomic level how nanotubes can convert to diamonds. Their computational studies in the October Physical Review B show that it is possible for carbon atoms from adjacent walls of multi-walled nanotubes to bond to each other to form both the cubic and hexagonal structures of diamond. While such nano-carat diamonds wont appear at the jeweler's anytime soon, researchers think that their strength and hardness may make them useful components of nanoscale machines.

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Raman laser
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First efficient diamond Raman laser paves the way to new defence technologies and improved laser surgery
Tomorrow's lasers may come with a bit of bling, thanks to a new technology that uses man-made diamonds to enhance the power and capabilities of lasers. Researchers in Australia have now demonstrated the first laser built with diamonds that has comparable efficiency to lasers built with other materials.
This "Raman" laser has applications that range from defence technologies and trace gas detectors to medical devices and satellite mapping of greenhouse gases. The special properties of diamonds offer a stepping stone to more powerful lasers that can be optimised to produce laser light colours currently unavailable to existing technologies.
Richard Mildren of Macqaurie University in Sydney, New South Wales, Australia and Alexander Sabella of the Defence Science and Technology Organisation in Edinburgh, South Australia developed the device, described in the current issue of the Optical Society (OSA) journal Optics Letters.

Source: Optical Society of America


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Carbon Rapture
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World's biggest diamond structure heads to the West End
The largest representation ever created of the atomic structure of diamond will be brought to the West End on Tuesday for public exhibition.
The sculpture is one of three works of science art portraying carbon made in recent weeks by the University of Keele, and called collectively Carbon Rapture.
Carbon Rapture will be located in the courtyard of Burlington House, in front of the Royal Academy of Arts, and the headquarters of Royal Society of Chemistry (RSC) who commissioned the dramatic new exhibit.

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Diamonds
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Diamonds will take center stage this month in countless wedding ceremonies and other celebrations. In addition to their usual role as symbols of enduring love and fidelity, diamonds are now also helping geologists unravel clues about how the earth's precious metal mineralisation was formed and why diamonds and some of these metals are found in only a few places around the world.
In a research paper published in this week's journal Nature, researchers from the Carnegie Institution and the University of Cape Town presented their findings after studying 2 billion year-old diamonds mined near the famed Bushveld Complex, a unique and mysterious geological formation in central South Africa. After analysing mineral inclusions within the diamonds, the researchers believe both the diamonds and the magmas that gave rise to the Bushveld Complex have an ancient subcontinental mantle source.

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