In 1962, researchers proposed that diamond’s typical cubic form might not be its hardest version. They believed a hexagonal type could be up to 50% harder. This quest has intrigued scientists ever since, and a recent discovery by a team from China may finally shed light on it.
In a new study published in Nature, the researchers detail how they created a small hexagonal diamond by compressing graphite at high temperatures. This diamond, which is about 1 millimeter wide, has been found to be slightly harder and more resistant to oxidation than regular cubic diamonds.
The team used advanced tools like X-rays and atomic-scale microscopes to confirm the diamond’s hexagonal structure, showing minimal defects. Crystallographer Oliver Tschauner from the University of Nevada highlighted the significance of their findings, stating this work might be the most accurate description of this rare material yet.
A Brief History
The concept of hexagonal diamonds began gaining attention five years after their prediction when scientists claimed to have found one inside a meteorite. They named it lonsdaleite. However, subsequent research questioned the legitimacy of both lonsdaleite and other lab-created versions, suggesting they were merely cubic diamonds with defects.
Fast forward nearly five decades, and lab advancements led to attempts at producing hexagonal diamonds. Some of these attempts were successful but the results were either too small or too short-lived to confirm their existence.
The Creation Process
The Chinese team sourced high-quality graphite for their experiment. They placed it between tungsten carbide anvils and subjected it to immense pressures—200,000 times that of the Earth’s atmosphere—and extreme temperatures, ranging from 1,300 to 1,900 degrees Celsius.
By carefully controlling the angle of compression, they were able to generate a hexagonal diamond, which was confirmed to be composed of carbon atoms in a unique arrangement.
Interestingly, while their hexagonal diamond showed increased stiffness and oxidation resistance, it was only marginally harder than typical diamonds, falling short of earlier expectations.
Not Alone in Discovery
Encouragingly, two other research groups have reported similar results, suggesting that the production of hexagonal diamonds may be reproducible. This consistency is crucial for potential real-world applications. Chongxin Shan, co-lead author of the study, believes this could finally convince skeptics of the diamond’s existence.
If these findings stand the test of time, it could lead to exciting developments in manufacturing. After all, traditional diamonds already have a range of industrial uses. A more durable variant could open new doors for technology and materials science.
The journey to uncover the true potential of hexagonal diamonds shows the ongoing pursuit of knowledge and innovation in material research. As scientists continue to study this mysterious gem, the possibilities are vast.
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Diamonds,material science
