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Case Study Series (CSS-ESRF-06-3)
Contact: Montserrat Capellas, capellas@esrf.fr
Leonid Dubrovinsky - geoscientist at the University of Bayreuth (Germany) and ESRF user
June 2006
Jules Verne would have been pleased to meet Leonid Dubrovinsky. This ESRF user's virtual journeys into the interior of the Earth take place on a daily basis and enlighten him with new discoveries. These are magnificent adventures that go beyond the abstract idea of understanding the Earth. The ESRF has become a usual and very useful tool for his research. Experiments at extreme conditions of temperature (1 K to 2200 Kelvin), pressure (up to 1.5 Mbar) and magnetic field (up to 30 Tesla pulsed) are already feasible at the ESRF. Extreme conditions are very important in many experiments and it also features as one of the main topics in the ESRF's Long Term Strategy.
Why are you studying the Earth?
All natural phenomena happening on the Earth have their origins somewhere inside. We still have trouble predicting earthquakes or volcano eruptions, for instance. If we know what are the materials in the Earth, we can gain a lot of information about what can happen on the surface. At the same time, understanding the world is a philosophical wish that has been pursued since a long time ago.
Do we know what is in the deep Earth?
The main constituents of the lower mantle are silicates (particularly, (Mg,Fe)(Si,Al)O3 perovskite) and oxides (mainly (Mg,Fe)O ferropericlase), and of the core are iron and nickel alloys. However, there may be more materials that we do not know yet. Our idea is to find out the properties of the constituents we know depending on the conditions where they are. Factors like the high temperature - it reaches 6000 degrees Kelvin - and the pressure - over 300 Gigapascal- can change the characteristics of substances. We also want to know how constituents can interact with each other taking into account the environment where they are set.
How can you reproduce the conditions in the core?
We come to the ESRF and other complimentary synchrotrons and we try to reproduce the temperature and pressure in the Earth. For the pressure, we use a diamond anvil cell, which presses the sample to the level we wish. I can't imagine how radiation high pressure geophysically (or, more generally, planetary sciences) oriented studies could be conducted without a synchrotron. I have been coming to the ESRF for the last decade and it is amazing the way experiments have evolved.
Have experiments become easier since the early days?
When we brought our first sample, it took us five days to start an experiment. Now, we can get diffraction images from the sample in diamond anvil cells in minutes. There have also been changes in the technique: before, all the experiments in high pressure were using the technique of diffraction, whereas now there are multiple combinations of techniques. We can also use this high pressure and high temperature experiments to test new materials.
How are new materials linked with your research?
Geosciences research can lead to the development of new materials. In my team, for example, we have just patented new aggregated diamond nanorods (ADNRs), which have originated from experiments on geomaterials. ADNRs are extremely hard and are three times more wear resistant than best known polycrystalline diamonds. They also have better thermal stability. Furthermore, we have recently produced an alloy of magnesium and iron, which is a combination previously thought to be impossible. We created it in conditions of high pressure and then brought it back to ambient conditions. Magnesium is widely used in modern technology, so maybe industry will be interested in using of our methodology of high-pressure alloying, who knows? My wife (Natalia Dubrovinskaia) is responsible for this discovery, I just collaborated.
Does Natalia also work on Earth research?
We both have the same basic training, but I am more concentrated in geosciences and she is focused on developing new materials and synthesis technologies. We collaborate in projects, but we are based in different departments.
Is science the main topic at your dinner time?
We inevitably talk about science at home. One of my two children has degrees in biotechnology and in mathematics and is now doing a PhD in biophysics, so we can say that science is in the family, in a way.
How will geosciences develop?
Geosciences will continue, but as it has already happened, methodology invented by geosciences will be transferred to the broader physical and chemical society and will lead to further developments. If you look at the ESRF's past, at the beginning I'd say around 80% of the proposals in high pressure were on geosciences, and so were the publications coming out of experiments. Now the number of proposals from geosciences has shrunk in favour of those from physics and chemistry.
Is the Earth always going to be unpredictable?
Prediction of physical phenomena behind global events is improving. I am positive that it will be clearly understood, sooner rather than later. However, I doubt that we can influence these phenomena. Nevertheless, there are countries like Japan, where people manage to live on a seismologic zone and they can handle it.
Leonid Dubrovinsky image is courtesy of: NASA/ESRF
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