Researchers resolve decades-long debate about shock-compressed silicon with unprecedented detail

They saw how the material finds a path to contorting and flexing to avoid being irreversibly crushed.


Silicon, an element abundant in Earth’s crust, is currently the most widely used semiconductor material and is important in fields like engineering, geophysics and plasma physics. But despite decades of studies, how the material transforms when hit with powerful shockwaves has been a topic of longstanding debate.

“One might assume that because we have already studied silicon in so many ways there is nothing left to discover,” said Silvia Pandolfi, a researcher at the Department of Energy’s SLAC National Accelerator Laboratory. “But there are still some important aspects of its behavior that are not clear.”

Now, researchers at SLAC have finally put this controversy to rest, providing the first direct, high-fidelity view of how a single silicon crystal deforms during shock compression on nanosecond timescales. To do so, they studied the crystal with X-rays from SLAC’s Linac Coherent Light Source (LCLS) X-ray laser. The team published their results in Nature Communications on September 21st. What they learned could lead to more accurate models that better predict what will happen to certain materials in extreme conditions.

“This is a great example of an experiment that’s necessary to better understand certain materials,” said SLAC scientist Arianna Gleason, who was the principal investigator. “You have to start simple, with single crystals, to know what you’re tracking and understand it in really detailed ways before you can build up complexity to give way to, say, the next semiconductor of the 21st Century that will allow the electronics industry to continue the remarkable progress seen in the past 50 years.”

Read more on the SLAC website

Karen Appel’s #My1stLight

Karen was a beamline scientist at DESY and is currently a beamline scientist at the European XFEL

My first synchrotron experiment was at beamline L at DORIS at DESY, which at that time just set up the possibility to do micro-focus X-ray fluorescence measurements. The first experiment I was involved in was headed by the group of Prof Schenk at the Institute of Mineralogy of the University of Kiel  and focused on minerals that were formed at high pressures and high temperatures. At that moment, I was a PhD student at the University of Bonn, working on metamorphic rocks and isotope geochemistry of rocks and got involved in the experiment, because I was interested in analytical methods that could be applied to minerals that were formed at high pressures and temperatures. Besides some connections through my earlier studies, my main interest was to learn about this new method of X-ray fluoresence. We investigated the chemical trace element composition (Rare Earth elements) of minerals that were formed during metamorphic processes and commonly show a gradient of the element distribution, which is related to the metamorphic formation process. 

As we were simply providing the samples, we had the chance to have a close look at the instrumentation. Having worked with commercial machines so far, I remember that I was very much impressed by the modular set- up of a beamline and this one-day experience motivated me to apply for a job that was offered from GFZ Potsdam that included a main part in experimental work at beamline L.

Later, as a postdoc, my experiences led me into the van Gogh experiment, where we used the polychromatic mode at beamline L and were able to detect the elemental distributions of a van Gogh painting. Now I am working at the High Energy Density Science instrument at the European XFEL, studying extreme states of matter, allowing me to work as a beamline scientist and also pursue my own scientific interests.

Image (above): Karen and her colleague working at the experimental station at the beamline L of DORIS III.

Credit: DESY

Image: DE: Die Experimentierstation HED (High Energy Density Science) dient der Erforschung von Materie unter extremen Druck- und Temperaturbedingungen oder sehr starken elektromagnetischen Feldern. Zu den wissenschaftlichen Anwendungen gehört die Untersuchung von Zuständen, wie sie im Inneren astrophysikalischer Objekte wie Exoplaneten bestehen, von Phasenzuständen unter extremem Druck, von Plasmen mit hoher Dichte oder von Phasenübergängen komplexer Feststoffe unter dem Einfluss starker Magnetfelder. EN: The HED experiment station will be used to study matter under extreme conditions of pressure, temperature, or electromagnetic fields. Scientific applications will be studies of matter occurring inside astrophysical objects such as exoplanets, of new extreme-pressure phases and solid-density plasmas, and of phase transitions of complex solids in high magnetic fields.

Credit: European XFEL / Jan Hosan

High-pressure experiments provide insight into icy planets

Research team determines compression behaviour of water ice in unprecedented detail

An international team of scientists has been using X-rays to take a look inside distant ice planets. At the PETRA III Extreme Conditions Beamline, they investigated how water ice behaves at high pressure, under conditions corresponding to those inside the planet Neptune, for example. At pressures up to almost two million times atmospheric pressure at sea level on Earth, the researchers were able to observe in unparalleled detail how water ice behaves under compression. The team, led by Hauke Marquardt from the University of Oxford, is presenting its findings in the scientific journal Physical Review B.

Planetary ices – such as water ice (H2O), methane ice (CH4) and ammonia ice (NH3) – make up large parts of the ice giants in our solar system and are very likely to occur inside many exoplanets, which are planets outside our solar system. “However, the physical properties and phase diagrams of these compounds are not sufficiently known at the pressures and temperatures that prevail inside planets,” explains Marquardt. “Previous experimental studies using X-ray diffraction in a static diamond anvil cell have contributed a great deal to our understanding of ices at high pressure, but they have been unable to adequately answer numerous questions.”

Read more on the DESY website

Image : Ice at room temperature: A mixture of water ice and liquid water in a high-pressure cell at a temperature around 25 degrees Celsius and a pressure of one gigapascal, which corresponds to 10 000 times atmospheric pressure

Credit: DESY, Hanns-Peter Liermann