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In nature, diamonds were formed billions of years ago in the depths of the earth’s crust under conditions of intense heat and pressure. Typically, diamonds form at a depth of about 150 to 200 kilometers (93 to 124 miles) below the surface of the Earth, where temperatures average 900 to 1,300 degrees Celsius (1650 to 2370 degrees Fahrenheit) and the pressure is about 50,000 times greater on the surface. This is also why diamonds are so coveted: it took millions of years to produce them under special conditions.
But now, scientists in Australia claim they can create diamonds in a couple of minutes, and at room temperature to boot.
Diamonds are forever … but it shouldn’t take that long to make them
Because diamonds are so rare, geologists have tried to develop methods for making man-made diamonds. It was not until the 1950s that Swedish and American scientists finally discovered how to convert graphite and molten iron into a synthetic diamond, fulfilling Jules Verne’s literary prediction.
The most common method of making synthetic diamonds used in the industry is called HPHT (high pressure, high temperature). During HPHT, carbon is subjected to as high temperatures and pressures as carbon that turned into diamonds billions of years ago.
In their new study, physicists from the Australian National University (ANU) and RMIT University in Melbourne described how they created two types of diamonds. One is about diamonds similar to those used in jewelry, the other is a harder-than-usual type called Lonsdaleite created by meteorite impacts.
The surprising thing is that both types of diamonds were generated at room temperature, which is a huge achievement, especially for the rare Lonsdaleite variety which is 58% harder than normal diamonds. However, scientists still had to apply enormous pressure on carbon atoms – the equivalent of 640 African elephants balancing on the toe of a dance shoe.
“The turning point in history is how we apply the pressure,” says ANU Professor Jodie Bradby. “In addition to very high pressures, we also allow the carbon to experience something called ‘shear’, which is like a twisting or sliding force. We believe this allows the carbon atoms to move into position and form the Lonsdaleite and the normal diamond. “
Small slices of diamonds were cut and then placed under the electron microscope so that researchers could better understand their structure and how they formed. In this way, they noticed that the materials formed inside bands, which they call “rivers”.
“Our images showed that regular diamonds only form in the middle of these Lonsdaleite veins with this new method developed by our interinstitutional team,” says RMIT Professor Dougal McCulloch. “Seeing these little ‘rivers’ of Lonsdaleite and regular diamonds for the first time was just amazing and really helps us understand how they could form.”
These man-made diamonds are not intended as jewelry, although there would be nothing wrong with using them in a wrong engagement. Instead, they are designed for industrial applications where the cutting of resistant materials or as protective shielding is required.
“Lonsdaleite has the potential to be used to cut ultra-solid materials at mining sites,” Bradby said in a statement.
The results appeared in the magazine Small.
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