Stories tagged diamond

Mar
13
2010

Photon computing

Diamond nanowires emit photons: A Harvard-based team has manufactured a matrix of diamond nanowires with defects called nitrogen vacancies. When stimulated with green light, these defects emit one red photon at a time. Such a construct is promising for the new field of quantum computing
Diamond nanowires emit photons: A Harvard-based team has manufactured a matrix of diamond nanowires with defects called nitrogen vacancies. When stimulated with green light, these defects emit one red photon at a time. Such a construct is promising for the new field of quantum computingCourtesy Zina Deretsky, NSF

Most computers and communications rely upon controlling the flow of electrons. Such devices would be faster and more secure if they used particles of light (photons).
A research team led by Marko Loncar just published how a "diamond nanowire device acts as a nanoscale antenna that funnels the emission of single photons from the embedded color center into a microscope lens."

"This exciting result is the first time the tools of nanofabrication have been applied to diamond crystals in order to control the optical properties of a single defect," said Loncar.

Faster and more secure

Not only is communicating through optical fibers more efficient, there is no easy way for eavesdroppers to "tap the line".

"The resulting device may prove easy to couple into a standard optical fiber. This novel approach is a key technological step towards achieving fast, secure computing and communication." nsf.gov/news

Learn more about diamond-based nanowire devices

Digging deep into diamonds Harvard Gazette

Lucy in the sky with diamonds
Lucy in the sky with diamondsCourtesy Travis Metcalfe and Ruth Bazinet, Harvard-Smithsonian Center for Astrophysics.

Just in time for Valentine's Day, astronomers discovered a star Feb. 13, 2004 that is thought to be a diamond crystal weighing 10 billion trillion trillion carats.

Click this link to learn more about Lucy, the star made out of diamond.

Nov
30
2008

Diamonds from Canada: Click on the mafic link for more photos related to hunting for diamonds near the Arctic Circle.
Diamonds from Canada: Click on the mafic link for more photos related to hunting for diamonds near the Arctic Circle.Courtesy mafic

Understand geology

Chuck Fipke, with a degree in geology, was hired out of college by Kennecott Copper to look for gold and copper. About 8 years later Superior Oil hired him to look, not for metals, but diamonds. A Superior geologist named John Gurney, discovered that the presence of chromite, ilmenite, and high-chrome, low-calcium garnet within kimberlite predicted the finding of diamonds. Fipke, combining what he understood of Gurney's work with results coming out of Russian labs and his own skills with field sampling, started looking for diamonds in Canada.

Using what you know, start looking

With Superior's backing, he teamed up with a geologist and pilot named Stewart Blusson, formed Dia Met Minerals, and headed north.

Drill for samples and work "upstream"

De Beers geologists were already looking for diamonds in Canada. Fipke knew that glaciers pushed everything southward so he looked further north. He also noticed that the further North he went the less worn were the edges of the diamonds.

Fipke got a helicopter and flew back and forth over the Arctic Circle, using a magnetometer to track variations in magnetic field that would suggest kimberlite. After thousands of miles and hundreds of hours in the air, he found a promising site near Lac de Gras, a barren world of lakes and rock and muskeg a few hundred miles outside the Arctic Circle.

Keep looking, don't give up

He'd been surveying for eight years. He hadn't found a single diamond. Superior had abandoned the diamond business. Dia Met's stock was trading at pennies a share.

I worked hard, and I mean really hard. I worked seven days a week from 8 am until 3 am. Every day. We drilled and drilled all winter when it was dark and the windchill was 80 below. Everyone thought I was crazy.

Become a billionaire

In 1991, Fipke found a kimberlite pipe (buried under 30 feet of glaciated sediment) with a concentration of 68 carats per 100 tons — the first Canadian diamonds ever found. Shares of Dia Met rocketed to $70.

Chuck Fipke had partnered with mining giant Broken Hill Proprietary Company (now BHP Billiton) to get the diamonds out; BHP opened the Ekati mine at Lac de Gras in 1998. Soon Dia Met's 29 percent share of the mine was worth billions. Fipke would go on to sell his chunk to BHP for $687 million, retaining 10 percent ownership in the mine, worth another $1 billion.

Diamonds from Canada now account for 10 percent of all diamonds by carat sold in the world. The country's four working mines produced 17 million carats in 2007.

Source: How a Rogue Geologist Discovered a Diamond Trove in the Canadian Arctic Wired

Aug
28
2007

How old is the earth?

Oldest diamond puzzles scientists
Oldest diamond puzzles scientists
Scientists mostly agree that the Earth is about 4.54 billion years old (USGS.gov). This age represents a compromise between the interpretations of oldest-known terrestrial minerals – small crystals of zircon from the Jack Hills of Western Australia – and astronomers' and planetologists' determinations of the age of the solar system based in part on radiometric age dating of meteorite material and lunar samples. (Read why meteorites were used here.)

How fast did Earth cool?

Earth's beginning is known as the Hadean—because geologists speculate the planet's surface boiled and bubbled with molten lava under a steady bombardment of comets and meteorites. Diamonds would never form in such conditions yet diamonds over 4.2 billion years old have now been found. Does this mean that the Earth cooled enough that a cool crust and maybe even oceans existed 4.25 billion years ago?

Oldest diamonds within zircon may give the answers.

Because no rocks older than 4 billion years had previously been found, the Hadean period of Earth was thought to be at least 500 million years. Zircons found in Jack Hills Austalia changed this thinking.
When a zircon forms from a solidifying magma, atoms of zirconium, silicon and oxygen combine in exact proportions (ZrSiO4) to create a crystal structure unique to zircon; uranium occasionally substitutes as a trace impurity. Atoms of lead, on the other hand, are too large to comfortably replace any of the elements in the lattice, so zircons start out virtually lead-free. The uranium-lead clock starts ticking as soon as the zircon crystallizes. Thus, the ratio of lead to uranium increases with the age of the crystal. Scientists can reliably determine the age of an undamaged zircon within 1 percent accuracy, which for the early earth is about plus or minus 40 million years.
Furthermore, the ratios of radioactive isotopes of neodymium and hafnium--two elements used to determine the timing of continental-crust-forming events--suggest that significant amounts of continental crust formed as early as 4.4 billion years ago.Scientific American

Explainations for the diamonds are uncertain.

Craig O'Neill, a geochemist with Sydney's Macquarie University, at first thought the diamonds were due to heavy meteroite bombardment, forming in large impact craters due to the huge pressures reached. Dr Nemchin agreed that the birth of the diamonds was key, although he speculated that they formed when new-formed hunks of the Earth's crust collided. Study co-author Wilde said, "The bottom line is that we really honestly don't know why they're (the diamonds) there." The 4.25-billion-year-old diamonds "suggest the additional possibility that the diamonds have formed by some process that is not yet understood." He suggests the researchers should test the diamonds' carbon isotopic composition and whether nitrogen is present as single or paired atoms. This would indicate the time spent in the mantle and whether it was under relatively high or low temperatures.
Dr Nemchin says analysis of the carbon isotopes would be the next obvious step and could provide clues about the possible existence of life forms 4.2 billion years ago.

Sources:

The study, led by Martina Menneken, a master's student at the Westfaelische Wilhelms-Universitaet, appeared in the Aug. 23, 2007 journal, Nature. Alexander Nemchin from Curtin University of Technology also contributed.
I also recommend the Scientific American article, "A cool early earth?" (October, 2005). I now have a better understanding of how diamonds and zirconium crystals can tell us about what the Earth was like more than 4 billion years ago.