Stanford researchers have found that with the right amount of pressure and surprisingly little heat, a substance found in fossil fuels can transform into pure diamond.
It sounds like alchemy: take a clump of white dust, squeeze it in a diamond-studded pressure chamber, then blast it with a laser. Open the chamber and find a new microscopic speck of pure diamond inside.
A new study from Stanford University and SLAC National Accelerator Laboratory reveals how, with careful tuning of heat and pressure, that recipe can produce diamonds from a type of hydrogen and carbon molecule found in crude oil and natural gas.
This study is published in the journal Science Advances.
Scientists have synthesized diamonds from other materials for more than 60 years, but the transformation typically requires inordinate amounts of energy, time or the addition of a catalyst – often a metal – that tends to diminish the quality of the final product. So, this research team wanted to see just a clean system, in which a single substance transforms into pure diamond – without a catalyst.
Understanding the mechanisms for this transformation will be important for applications beyond jewelry. Diamond’s physical properties – extreme hardness, optical transparency, chemical stability, high thermal conductivity – make it a valuable material for medicine, industry, quantum computing technologies and biological sensing.
Natural diamonds crystallize from carbon hundreds of miles beneath Earth’s surface, where temperatures reach thousands of degrees Fahrenheit. Most natural diamonds unearthed to date rocketed upward in volcanic eruptions millions of years ago, carrying ancient minerals from Earth’s deep interior with them.
As a result, diamonds can provide insight into the conditions and materials that exist in the planet’s interior. Diamonds are vessels for bringing back samples from the deepest parts of the Earth.
To synthesize diamonds, the research team began with three types of powder refined from tankers full of petroleum. It’s a tiny amount.
The researchers use a needle to pick up a little bit to get it under a microscope for their experiments.
At a glance, the odorless, slightly sticky powders resemble rock salt. But a trained eye peering through a powerful microscope can distinguish atoms arranged in the same spatial pattern as the atoms that make up diamond crystal. It’s as if the intricate lattice of diamond had been chopped up into smaller units composed of one, two or three cages.
Unlike diamond, which is pure carbon, the powders – known as diamondoids – also contain hydrogen.
The researchers loaded the diamondoid samples into a plum-sized pressure chamber called a diamond anvil cell, which presses the powder between two polished diamonds. With just a simple hand turn of a screw, the device can create the kind of pressure you might find at the center of the Earth.
Next, they heated the samples with a laser, examined the results with a battery of tests, and ran computer models to help explain how the transformation had unfolded
They found that the three-cage diamondoid, called triamantane, can reorganize itself into diamond with surprisingly little energy.
At 900 Kelvin – which is roughly 1160 degrees Fahrenheit, or the temperature of red-hot lava – and 20 gigapascals, a pressure hundreds of thousands of times greater than Earth’s atmosphere, triamantane’s carbon atoms snap into alignment and its hydrogen scatters or falls away.
The transformation unfolds in the slimmest fractions of a second. It’s also direct: the atoms do not pass through another form of carbon, such as graphite, on their way to making diamond.
News Source: Standford
