In a new experiment, scientists have used a powerful X-ray laser to transform PET plastic into tiny diamonds, similar to those that can fall on ice giant planets.
Using powerful lasers, the team extracted samples of PET, a common material used in plastic bottles, to generate intense heat and pressure to form tiny diamonds that can naturally fall on planets like Uranus and Neptune.
New the study was published in the journal Science Advances.
Here on Earth, diamonds are valued for their rarity, but on other planets they may seem as common as stones. On ice giants like Uranus and Neptune, extreme pressure is thought to compress elements like hydrogen and carbon to form hard diamonds, which then fall into the atmosphere like rain.
This phenomenon has not been directly discovered, but in 2017 a group of scientists reported that they had recreated the process in the laboratory. They did this by firing the world's most powerful Linac Coherent Light Source (LCLS) X-ray laser on samples of hydrocarbon materials. This instantly heated them up to temperatures of up to 6,000°C (10,800°F) and set off powerful shock waves of millions of atmospheres of pressure, forming tiny “nanodiamonds”.
Although experiments have shown that this is technically possible, the team says that the original hydrocarbon materials, such as polystyrene, did not exactly mimic the elements present inside these ice giants. Oxygen is also present in large quantities, so the researchers investigated other materials that could introduce this key element into the mixture.
The scientists settled on PET, a form of plastic commonly used for food and beverage packaging that has a good balance between carbon, hydrogen and oxygen. The team repeated the experiment by running PET thin film samples with LCLS and then using two different imaging techniques to test not only whether nanodiamonds formed, but how fast and how much they grew. Scientists have indeed found diamonds with a density of up to 3.87 grams per cubic centimeter.
“The effect of oxygen was to accelerate the splitting of carbon and hydrogen and thus stimulate the formation of nanodiamonds. This meant that carbon atoms could more easily combine and form diamonds,” said Dominik Kraus, author of the study.
This study not only supports the hypothesis of diamond rain on ice giant planets, but, according to scientists, it also demonstrates a new potential technology for the production of these tiny diamonds, which are used in industrial abrasives, polishing compounds and, perhaps someday, highly sensitive quantum sensors.