Physicists Develop Lab-Grown Diamond Tougher Than Natural Ones

Scientists have once again created a synthetic diamond even tougher than natural ones, using a novel approach to diamond formation.

By subjecting graphite—a super-hard material in its own right—to extreme pressure and heating it to 1,800 K (1,527 °C or 2,780 °F), the researchers produced a diamond with a hexagonal lattice structure instead of the typical cubic one. This form, known as hexagonal diamond or lonsdaleite, was first identified over 50 years ago in meteorite impact sites. However, this study provides the strongest evidence yet that its unique internal structure enhances hardness.

“Most natural and synthetic diamonds have a cubic lattice, while the rare hexagonal structure has remained largely unexplored due to the low purity and small size of previous samples,” the researchers explain. “Synthesizing hexagonal diamond remains challenging, and even its existence has been debated.”

The newly created stone reaches a hardness of 155 gigapascals (GPa), significantly surpassing natural diamond, which maxes out around 110 GPa. It also exhibits impressive thermal stability, remaining intact up to at least 1,100 °C (2,012 °F), compared to 900 °C (1,652 °F) for nanodiamonds commonly used in industrial applications. While natural diamond can withstand higher temperatures, this is only possible in a vacuum.

Scaling Up Hexagonal Diamond Synthesis: Unlocking New Pathways Through High-Pressure Techniques

Beyond overcoming previous challenges in hexagonal diamond synthesis, the researchers identified potential ways to scale up the process. “We found that when graphite is compressed to much higher pressures than previously studied, hexagonal diamond forms more readily from post-graphite phases once heat is applied,” they report.

Although large-scale production is still a long way off, the material’s exceptional hardness and thermal stability suggest promising applications in drilling, machinery, and data storage.

This is not the first attempt to create hexagonal lattice diamonds in the lab. A 2016 study successfully synthesized them from amorphous carbon, a formless material. However, this latest method provides a new, proven pathway to producing ultra-hard diamonds, paving the way for future research and potential applications.

“Our findings shed light on how graphite transforms into diamond under extreme conditions, opening new opportunities for fabricating and utilizing this extraordinary material,” the researchers conclude.

Read Original Article: Science Alert

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