Scientists synthesise new materials at terapascal pressures for the first time

12-05-2022

A team led by the University of Bayreuth (Germany) has synthesized, for the first time, new materials at terapascal pressures, using the ESRF’s ID11 and a unique diamond anvil cell. The results are published in the journal Nature.

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Matter changes with variations of pressure and temperature, which allows the tuning of many material properties. These possibilities can shed light onto scientific questions, such as the fundamental understanding of the Universe or lead to targeted design of advanced materials. For example, today super-abrasive cubic Boron Nitride is used for grinding high-quality tool steels and artificial diamonds created using high temperature and high pressure are more prevalent than natural ones.

A team of scientists led by the University of Bayreuth has synthesized new materials at terapascal pressures using laser heating for the first time. The team used rhenium-nitrogen compounds as models to show that studies at pressures three times higher than pressure in the center of the Earth are now possible. Natalia Dubrovinskaya, professor at the University of Bayreuth and one of the corresponding authors of the paper, explains the relevance of these compounds:  “These novel rhenium-nitrogen compounds showed that at ultra-high pressures we can make materials that cannot be made at lower pressures/temperatures, and uncover fundamental rules of physics and chemistry. We found, for example, that due to a huge compression, rhenium behaves chemically in a similar way to iron”.

Schematic illustration of the DAC assembly.jpg 2022-04-08_ID11 USERS-18.jpg (USER TEAM AT ID11)

Schematic illustration of the Diamond Anvil Cell assembly (left) and researcher Saiana Khandarkhaeva on beamline ID11 (right). Credits: Timofey Fedotenko (illustration) and Chantal Argoud (picture).

The outcome of this research is the result of several experiments carried out at beamline ID11 of the ESRF, combined with a highly specialized toroidal and double-stage anvil cells designed and made at the University of Bayreuth. Using X-ray diffraction on the microcrystals in situ, the researchers could precisely characterise the chemistry of the new materials. Until today, only theoretical calculations provided information about the structure and properties of materials at such extreme pressure-temperature conditions, but the predictive power of these theories proved to be limited.

“Our first experiments took place before the EBS upgrade at the ESRF and we needed about a week to measure one cell. We did a very similar experiment after EBS and we got even better data in a matter of hours, so the benefit of EBS is very clear”, explains Leonid Dubrovinsky, also corresponding author of the paper.

The researchers used beamline ID11, which is specialised in spatially-resolved diffraction rather than high pressure experiments. “ID11 has a very small beam and an incredibly good resolution and with their dedicated diamond anvil cell the experimental sessions were very successful”, explains Carlotta Giacobbe, scientist on the beamline and also author of the research. Dubrovinskaya adds: “We started trial experiments 6 years ago and still today, there are no other beamlines that have a proven record of single crystal X-ray diffraction data collection on sub-micron size samples in diamond anvil cells”.

The scientists will now focus on testing how the chemistry and physics rules (presently known for ambient and low pressures) change at 1000GPa pressures. They will also try to answer scientific questions, such as what is in the interior of large (like Neptune or Uranus) or extraterrestrial super-Earth planets. For this they will complement measurements on ID11 with the upgraded ID27 beamline and the future ID18, where spectroscopy experiments at terapascal pressures should be possible.

Reference:

Dubrovinsky, L., et al, Nature,  605, pages274–278 (2022).

Text by Montserrat Capellas Espuny

Top image: Crystal structures of Re7N3 observed in laser-heated dsDACs. Credits: Dr. Timofey Fedotenko.