Scientists create nanodiamonds from plastic bottles

The new research provides a more complete picture of how diamond rain forms on other planets.
Baba Tamim
Diamond rain.
Diamond rain.


Researchers have discovered that "diamond rain," unique precipitation that has long been speculated to occur on icy giant planets, may occur more frequently than previously believed.

To learn more about the circumstances on the icy giant planets Neptune and Uranus, a group of researchers from Germany and France has created an intriguing experiment, according to an article published by on Friday.

In a prior experiment, scientists looked at a plastic formed of hydrogen and carbon, two elements that are important to understanding the entire chemical makeup of Neptune and Uranus.

In the most recent experiment, the researchers used PET plastic, which is commonly used in food packaging, plastic bottles, and containers, to more accurately reproduce the composition of these planets.

"The effect of the oxygen was to accelerate the splitting of the carbon and hydrogen and thus encourage the formation of nanodiamonds," said Dominik Kraus, a physicist at HZDR and professor at the University of Rostock.

"It meant the carbon atoms could combine more easily and form diamonds."

The new research provides a complete picture of how diamond rain forms on other planets and could lead to a new method of producing nanodiamonds, which have a wide range of applications in drug delivery, medical sensors, noninvasive surgery, sustainable manufacturing, and quantum electronics.

"The earlier paper was the first time that we directly saw diamond formation from any mixtures. Since then, there have been quite a lot of experiments with different pure materials," said Siegfried Glenzer, director of the High Energy Density Division at SLAC.

"But inside planets, it's much more complicated; there are a lot more chemicals in the mix. And so, what we wanted to figure out here was what sort of effect these additional chemicals have."

Diamonds from Plastic bottles

To generate shock waves in the PET, the researchers used a high-powered optical laser at the Matter in Extreme Conditions (MEC) instrument at SLAC's Linac Coherent Light Source (LCLS). Then, using LCLS X-ray pulses, they investigated what happened in the plastic.

They observed the atoms of the material rearranging into small diamond regions using a technique known as X-ray diffraction. And then used, small-angle scattering, a method to measure how fast and large those regions grew at the same time, which was not used in the first paper.

The scientists determined that these diamond regions grew up to a few nanometers wide using this additional method. They discovered that the presence of oxygen in the material allowed the nanodiamonds to grow at a faster rate.

Diamonds on Neptune and Uranus, the researchers predict, will grow much larger than the nanodiamonds produced in these experiments, possibly reaching millions of carats in weight.

They could slowly sink through the planets' ice layers and form a thick layer of bling around the solid planetary core over thousands of years, the researchers noted.

'Hot, black ice'

The scientists also discovered evidence that superionic water could form in the presence of diamonds.

This newly discovered phase of water, which is often referred to as "hot, black ice," exists at extremely high temperatures and pressures.

Water molecules disintegrate under these extreme conditions, and oxygen atoms form a crystal lattice in which hydrogen nuclei float freely.

"We know that Earth's core is predominantly made of iron, but many experiments are still investigating how the presence of lighter elements can change the conditions of melting and phase transitions," said SLAC scientist and collaborator Silvia Pandolfi.

"Our experiment demonstrates how these elements can change the conditions in which diamonds are forming on ice giants. If we want to accurately model planets, then we need to get as close as we can to the actual composition of the planetary interior."

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