Sometimes the most exciting discoveries are made by chance. This also applies to a group of researchers from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), the Ecole Polytechnique de Paris and the University of Rostock. Actually, the team wanted to find out what physical processes can be observed on icy planets like Neptune or Uranus, but they found a method to make so-called nanodiamonds from simple polyethylene bottles.
To do this, researchers led by Dominik Kraus, Professor of Radiation Physics, a thin film of PET plastic with a laser. They were then able to use high powered laser flashes to verify what had happened. It turned out that diamonds are created inside ice giants like on an assembly line. The reason is the extreme conditions that combine thousands of degrees Celsius with pressure millions of times higher than on Earth. This in turn could be simulated with laser and PET.
6,000 degrees centigrade by laser
The material is briefly heated to 6,000 degrees Celsius. Shock waves were produced, building up a compressive pressure of a million times atmospheric pressure, similar to that of ice planets. A few nanoseconds were enough. Small diamonds turned out, they said nanodiamonds.
Previous experiments had been done with thin films of hydrocarbons. However, this only partially simulated ice planets, because the oxygen present there was missing. The solution: PET. Because it has “a good balance of carbon, hydrogen and oxygen,” which in turn can be used well as a simulation of ice planets, according to Kraus in a press release.
The experiments themselves were carried out in the US, where SLAC in California has a particle accelerator-based X-ray laser, the Linac Coherent Light Source (LCLS). A combination of intense laser flashes simultaneously measures and analyzes the final result. It is even possible to determine how fast and how large nanodiamonds grow. The oxygen contained in PET was very helpful, according to the researchers. The water formed in the process assumed the so-called superionic state. This may explain why the ice giants have a magnetic field, because water conducts electricity. Whether there is a mixture of nanodiamonds and superionic water on Uranus and Neptune has not yet been definitively clarified.
The researchers’ next goal is to use the method to establish a kind of factory line for nanodiamonds that can be manufactured with great precision. The material could be used for cleaning and polishing purposes, but also for new catalysts for COtwo-Decomposition or even novel quantum sensors. Previous methods of producing these diamonds, on the other hand, seem outdated and use explosives.
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