Researchers at the Center for Multidimensional Carbon Materials (CMCM) within the Institute for Basic Science (IBS) have made a groundbreaking discovery in diamond growth. They have successfully grown diamonds using a liquid metal alloy at just 1 atmosphere of pressure and 1025 °C, challenging the prevailing belief that diamonds can only be grown under extremely high pressure and temperature conditions.
The team, led by Director Rod Ruoff, conducted hundreds of experiments before finding the right combination of gallium, iron, nickel, and silicon in the liquid metal alloy. The diamonds grew in the sub-surface of the alloy when exposed to methane and hydrogen under the new milder conditions.
Yan Gong, a graduate student and first author, noticed a “rainbow pattern” on the solidified metal, which turned out to be diamonds. This discovery allowed the team to identify the optimal parameters for reproducible diamond growth.
The synthesized diamond film has a very high purity and contains silicon-vacancy color centers. Dr. Meihui Wang notes, “This synthesized diamond with silicon-vacancy color centers may find applications in magnetic sensing and quantum computing.”
Understanding the Growth Mechanism
The researchers found that the diamonds nucleate and grow in an amorphous subsurface region of the liquid metal, which has a high concentration of dissolved carbon atoms. They also discovered that silicon plays a critical role in the nucleation process, with theoretical calculations suggesting that small carbon clusters containing silicon atoms might serve as “pre-nuclei” for diamond growth.
Flexibility in Liquid Metal Composition
The team’s growth method allows for flexibility in the composition of the liquid metal alloy. Dr. Da Luo remarks, “Our optimized growth was achieved using the gallium/nickel/iron/silicon liquid alloy. However, we also found that high-quality diamond can be grown by substituting nickel with cobalt or by replacing gallium with a gallium-indium mixture.”
Director Ruoff concludes, “There are numerous intriguing avenues to explore! New designs and methods for introducing carbon atoms and/or small carbon clusters into liquid metals for diamond growth will surely be important, and the creativity and technical ingenuity of the worldwide research community seem likely to me, based on our discovery, to rapidly lead to other related approaches and experimental configurations.”
This research, supported by the Institute for Basic Science, has been published in the journal Nature.
