You mentioned that scientists don't know where the carbon comes from. What are some possible sources? In some cases, the carbon seems to have originated within the mantle of the Earth, so carbon that was already in the Earth.
In other cases, there's evidence very curiously to suggest that the carbon may have originated near the surface of the Earth. The thinking there is that this carbon could have literally been carbon that was part of carbonate sediments or animals, plants, shells, whatever, that was carried down into the upper mantle of the Earth by the plate tectonics mechanism called subduction.
We really don't know how long it takes. There have been attempts to try to date inclusions in different parts of diamonds, and those have largely been unsuccessful. It may be that diamonds form over periods as short a time as days, weeks, months to millions of years. Typically, as with many crystals that grow on the Earth, it's not a continuous process. The diamonds may start to grow and then there may be an interruption for some reason — a change in conditions, temperature, pressure, source of carbon, whatever—and they could sit for millions, hundreds of million of years, and then start growing again.
That's part of the problem of trying to put some sort of a growth period on them; things don't always occur continuously in the Earth. We can grow diamonds in the lab and we can simulate conditions there. But there are things we have to do to grow diamonds in the laboratory that aren't obvious as to how it happens in the Earth. In the laboratory, they're typically grown, but there's some catalyst. Some metals are often added to cause the diamonds to grow, but these same catalysts are not observed in the diamonds from the upper mantle of the Earth.
It is difficult to say for certain how long it takes for diamonds to form under natural conditions. But, what we know, is that diamonds form in the upper mantle of the earth's crust — around a hundred miles beneath your feet. But, it is exactly this combination of intense heat and high-pressured mineral friction that creates the perfect conditions for diamonds to grow.
So, how do diamonds get from all the way down in the earth's mantle, to all the way up here where we can mine them out of the surface?
Scientists believe that the diamonds which humans have found on the earth's surface were brought up by a volcanic eruption. Most earth-mined diamonds are deep within the hardened magma on which they traveled. This eruption, likely, occurred hundreds of millions of years ago when the planet was rife with violent and constant volcanic activity.
The diamonds which we mine were already formed at the time that they traveled to the surface by way of this volcanic eruption. Scientists call these diamonds, Kimberlite diamonds — as they come to the surface by the process of the Kimberlite eruption. This eruption must have been violent, sudden, and short-lived.
As if truly from the Gods above, meteorites have also been known to deliver diamonds. Since carbon is the fourth most abundant element in the universe, it should come as no surprise that diamonds are not exclusive to Earth.
When scientists tracked their first meteorite impact, they were not surprised to find diamonds, but were shocked by the size of the diamonds. The first definitively man-made diamond was created in the General Electric laboratory in This first artificial diamond was created through the process of High Pressure High Temperature HPHT , which tries to replicate nature by superheating and applying force to diamond seeds. Synthetic diamonds are more commonly made using Chemical Vapor Deposition CVD , which can take 28 days starting with diamond seeds that are superheated in plasma and resulting in a cube-shaped diamond.
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Send code to my email. This website uses cookies. Coe and his colleagues at Element Six proved this was possible just over a year ago [ Science , , ] and now can grow high-quality, single-crystal diamond wafers that are 5 mm square. He predicts that within the next four years the company will be cranking out 4-inch square wafers. Both Coe and Linares suggest that, thanks to its high thermal conductivity and electrical carrier mobility, single-crystal semiconducting diamond will be the ultimate material for fashioning high-powered electronic devices.
Element Six is already making some simple prototype devices, such as switches, from p-type semiconducting diamonds, Coe says. But most devices will require both hole-conducting p-type and electron-conducting n-type diamond semiconductors. The former is easy: Both Element Six and Apollo report that they can use their CVD methods to make boron-doped single-crystal diamond wafers that are excellent p-type semiconductors.
Producing n-type semiconducting diamond has proven more challenging, however. A number of potential n-type dopants have been investigated, most notably phosphorus. A group led by Hisao Kanda of Japan's National Institute for Materials Science has shown that doping diamond with phosphorus gives n-type semiconducting diamond.
The team has gone on to show that phosphorus-doped and boron-doped diamond can be combined to make a simple electrical device called a p-n junction.
But so far neither phosphorus nor any other n-type dopant has demonstrated exactly the right electrical properties, according to Butler.
Despite this promising development, Angus--whose own lab is doping CVD diamond with a combination of boron and sulfur to get n-type semiconductivity--comments that "all of the n-type work, including ours, is interesting in a scientific sense but not yet practical for devices. The payoff for such work is potentially huge: Today's microchips are running hotter and hotter because more and more transistors are being crammed onto them.
If the trend continues, silicon may not be able to take the heat. Diamond could be the perfect solution. Despite its superior combination of electrical, optical, thermal, and chemical properties, though, diamond may never totally replace silicon for two reasons: Silicon is both cheap and firmly entrenched in the computer industry.
Still, Reza Abbaschian, a professor of materials science and engineering at the University of Florida, Gainesville, whose lab helped to perfect Gemesis' diamond-growing method, believes that "for certain specialized applications, such as devices that run at high power or high temperature, diamond may be just the ticket. Contact us to opt out anytime. Contact the reporter. Submit a Letter to the Editor for publication. Engage with us on Twitter. The power is now in your nitrile gloved hands Sign up for a free account to increase your articles.
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