New studies show that iron, the principal constituent of the innermost parts of the earth’s core, becomes unusually ‘soft’ at the extreme pressures and temperatures that prevail there. The findings, now being published in Science, enhance our possibility of understanding the innermost parts of the earth and how earthquakes occur, for example. In a more immediate perspective, scientists will have new tools for developing better materials.The findings were attained by a team of Swedish and Russian researchers, who used advanced simulations on Swedish supercomputers. This new knowledge explains some of the seismic data-signals from earth tremors-that stations around the world gather and that have puzzled scientists until now.
This dual nature of iron has been an enigma to researchers for more than 50 years, since iron in laboratory experiments has not evinced any tendency whatsoever to behave like a fluid under high pressure. The reason for this is the much lower temperatures in laboratory experiments compared with the center of the earth.
The solution to the riddle of this ‘soft’ iron lies in the how the iron atoms are arranged and can move under the conditions that prevail in the inner parts of the earth. The conditions can be likened to a solid structure in which the parts, instead of being nailed to each other, are fastened together with rubber bands. This makes it extremely easy for certain parts to shift in relation to each other.
A more scientific description is that the iron at the center of the earth cannot be depicted as an average of single crystalline iron. Instead, it is a so-called polycrystalline material with liquid-like granule edges and masses of defects in the structure. Anatoly Belonoshko, in collaboration with his colleagues Natalia Skorodumova and Anders Rosengren, has been able to show that an external disturbance like shear is rapidly mitigated by a migration of atoms and a gliding of the liquid-like granule edges.
Source: Science Daily
Image: Flickr/Rogiro
Tags: Mystery | Earth | Core
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