Growth of diamonds in liquid metal at standard atmospheric pressure

Growth of diamonds in liquid metal at standard atmospheric pressure
by Riko Seibo
Tokyo, Japan (SPX) Apr 26, 2024

The typical process for creating synthetic diamonds involves high-pressure, high-temperature methods, using pressures around 5-6 GPa and temperatures between 1300-1600 C. Yet, researchers at the Institute for Basic Science (IBS), led by Director Rod RUOFF and his team, have developed a method to grow diamonds at 1 atmosphere pressure and 1025 C. This new approach utilizes a liquid metal alloy, significantly simplifying and potentially scaling the production process.

"This pioneering breakthrough was the result of human ingenuity, unremitting efforts, and the concerted cooperation of many collaborators," stated Ruoff. His team's method involved extensive parameter adjustments in a specially designed cold-wall vacuum system, which allowed for rapid cycling between vacuum and gas exposure, speeding up their experimental trials.

Ruoff explained, "We had been running our parametric studies in a large chamber (named RSR-A with an interior volume of 100 liters) and our search for parameters that would yield growth of diamond was slowed due to the time needed to pump out air (about 3 minutes), purge with inert gas (90 minutes), followed by pumping down again to vacuum level (3 minutes) so that the chamber could then be filled with 1 atmosphere pressure of quite pure hydrogen/methane mixture (again 90 minutes); that is over 3 hours before the experiment could be started!" Dr. Won Kyung SEONG's design of a smaller chamber reduced this time to 15 minutes, greatly accelerating the research.

"Our new homebuilt system (named RSR-S, with an interior volume of only 9 liters) can be pumped out, purged, pumped out, and filled with methane/hydrogen mixture, in a total time of 15 minutes. Parametric studies were greatly accelerated, and this helped us discover the parameters for which diamond grows in the liquid metal!" remarked Seong.

The discovery showed that diamond grows in the sub-surface of a liquid metal alloy when exposed to a methane and hydrogen mixture. Yan GONG, a graduate student and first author of the study, noted an unexpected 'rainbow pattern' indicating the growth of diamonds in the alloy, leading to a reproducible method for diamond formation.

"Our synthesized diamond with silicon-vacancy color centers may find applications in magnetic sensing and quantum computing," added coauthor Dr. Meihui WANG.

High-resolution imaging and synchrotron X-ray diffraction confirmed the high purity of the diamond phase. The team's findings suggest that the presence of silicon is crucial in the nucleation and growth of diamonds, potentially revolutionizing the field by providing a simpler, scalable method for diamond synthesis.

Ruoff's team is continuing to explore this method, suggesting that variations in liquid metal composition could yield different results, potentially leading to further innovations in the production of synthetic diamonds.

Research Report:Growth of diamond in liquid metal at 1 atm pressure