Making Diamonds Doesn’t Require Extreme Pressure Anymore

Researchers, led by Director Rod Ruoff at the Center for Multidimensional Carbon Materials (CMCM) in the Institute for Basic Science (IBS), as well as graduate students from Ulsan National Institute of Science and Technology (UNIST), have successfully grown diamonds.

They achieved this breakthrough under conditions of 1-atmosphere pressure and at 1025°C. Their method involved using a special liquid metal alloy made of gallium, iron, nickel, and silicon.

This achievement marks a significant departure from previous methods. The discovery offers promising ways for more scientific exploration and the potential to scale up diamond production in innovative ways, as reported by “ScienceDaily.”

Growing diamonds using a home-built vacuum system

Under Ruoff’s guidance, the research team carried out numerous experiments. They made several hundred adjustments to various parameters and explored different experimental methods.

After rigorous efforts, they successfully grew diamonds using a home-built, cold-wall vacuum system.

Ruoff explained research progress was hindered by the lengthy setup process in the large chamber, RSR-A. It took over three hours.

This involved pumping out air for about three minutes, purging with inert gas for ninety minutes, pumping down to vacuum level again for three minutes, and then filling the chamber with a pure hydrogen/methane mixture for another ninety minutes before the experiment could commence.

To address this issue, Ruoff enlisted the expertise of Dr. Won Kyung Seong to develop a more efficient chamber. Seong commented that they designed and constructed a smaller chamber, called RSR-S, with a volume of only nine liters. This new system drastically reduced setup time to just fifteen minutes.

With quicker pumping, purging, and filling processes, they were able to accelerate the parametric studies significantly. This acceleration was crucial in identifying the parameters necessary for diamond growth within the liquid metal.

Diamond growing in the sub-surface of a liquid metal

The team uncovered that diamonds form beneath the surface of a liquid metal blend composed of 77.75 percent gallium, 11 percent nickel, 11 percent iron, and 0.25 percent silicon (based on atomic percentages). This phenomenon occurs when the mixture is exposed to methane and hydrogen under 1-atmosphere pressure at approximately 1025°C.

Yan Gong, a graduate student from UNIST and the primary author, said that, during one experiment with the RSR-S system, he observed a “rainbow pattern” spanning a few millimeters on the bottom surface of the solidified metal piece. This was after conducting the experiment and cooling down the graphite crucible to solidify the liquid metal.

Upon further investigation, they discovered the rainbow colors were indicative of diamond presence. This revelation enabled them to pinpoint the parameters conducive to consistent diamond growth.

In this new method, diamond formation initiates without requiring the presence of traditional seed particles. These are typically used in conventional high-pressure, high-temperature (HPHT) settings as well as during chemical vapor deposition (CVD) synthesis methods.