Research that investigates the mechanisms behind diamond formation, and uncovers new ways to produce synthetic forms of the unique stone, could mean big things, and not just for the coffers of jewelers around the world. A new type of artificial diamond developed by scientists at Stanford University sheds yet more light on this high-pressure production process, with a molecule found in crude oil and natural gas serving as their starting point.
Conventional diamonds take shape hundreds of miles beneath the Earth's surface, under extreme heat and pressure that causes carbon to crystalize into the valuable stones. The ones we see above ground were shot upwards towards the surface through volcanic eruptions millions of years ago.
Scientists have spent decades tinkering with different ways to turn various materials into synthetic versions, with diamond giant De Beers even getting in on the act. These methods, however, have generally involved massive amounts of energy and require catalysts to trigger the transformation. The researchers at Stanford’s School of Earth, Energy & Environmental Sciences set out to find a simpler way of doing things.
“We wanted to see just a clean system, in which a single substance transforms into pure diamond – without a catalyst,” said the study’s lead author, Sulgiye Park.
In crafting their new synthetic diamonds, the scientists began with powders refined from tanks of petroleum. Inspecting these materials through a powerful microscope, the team observed patterns of atoms in the powders that were organized in the same way as atoms that make up diamond crystals, presenting as small units made up of one, two or three cages.
Unlike conventional diamonds, these different diamondoids, as they are known, don't consist purely of carbon, in that they contain hydrogen as well. The team then packed these diamondoids into what is known as a diamond anvil cell, which is a device scientists often use to create extreme pressures and produce ultra-hard materials.
These materials were then heated with a laser, and through a series of tests and simulations, the team found that the three-cage diamondoid was able to transform into a pure diamond with very little energy. Subjected to a temperature of around 1,160 °F (627 °C) and pressure many times greater than that in the Earth's atmosphere, the three-cage diamondoid's carbon atoms swiftly snapped into alignment and the hydrogen disappeared from the mix.
All of this takes place in a tiny fraction of a second, and the researchers note the technique is capable of producing little more than tiny specks of diamond. Its real value lies in the insights it can offer in terms of how diamonds can be formed.
“Starting with these building blocks,” Mao said, “you can make diamond more quickly and easily, and you can also learn about the process in a more complete, thoughtful way than if you just mimic the high pressure and high temperature found in the part of the Earth where diamond forms naturally.”
Improving our understanding of how these synthetic diamonds can be formed could have ramifications beyond the jewelry industry. The hardness, transparency, chemical stability, thermal conductivity and other unique attributes of diamonds can make them useful to scientists in fields ranging from medicine, to biological sensing, to quantum computing.
“If you can make even small amounts of this pure diamond, then you can dope it in controlled ways for specific applications,” said study senior author Yu Lin.
The research was published in the journal Science Advances.
Source: Stanford University