A laser blast produces miniature diamonds from old plastic. That’s right, the same kind used in soda bottles.
When compressed to about a million times Earth’s atmospheric pressure and heated to thousands of degrees Celsius, polyethylene terephthalate, or PET, shape nanodiamondsphysicist Dominik Kraus and colleagues report September 2 in Progress of science.
Giant ice planets, such as Neptune and Uranus, have similar temperatures, pressures and combinations of chemical elements to the materials in the study, suggesting that diamonds may rain down on these planets. In addition, the researchers say, the new technique could be used to make nanodiamonds for use in quantum devices and other applications.
In the new study, the researchers trained lasers on plastic samples. Each laser burst sent a shock wave hurtling through the plastic, increasing the pressure and temperature inside. Probing the material with bursts of X-rays revealed that nanodiamonds had formed.
Previous studies had created diamonds by compressing hydrogen and carbon compounds. But PET, which is commonly used in food and beverage packaging, contains not only hydrogen and carbon, but also oxygen. That makes it a better match for the composition of giant ice planets like Neptune and Uranus. Oxygen appears to help diamond formation, says Kraus, of the University of Rostock in Germany. “Oxygen sucks up hydrogen,” he says, leaving behind carbon that can then form diamond.
Nanodiamonds are commonly produced using explosives, says Kraus, a process that is not easy to control. The new technique could create nanodiamonds that are more easily tailored for particular uses, such as quantum devices made with flawed diamonds where, for example, nitrogen atoms replace some of the carbon atoms (Serial number: 7/6/18).
“The idea is pretty cool. You carry a plastic water bottle; you hit it with a laser to make a diamond. How practical it is, I don’t know,” says physicist Marius Millot of the Lawrence Livermore National Laboratory in California, who was not involved in the new study. It’s not clear how easily the diamonds could be recovered, he says. But, “it’s pretty good to think about the idea.”