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The temperature near the center of the earth, according to new data, is 6,000 ° C – a thousand degrees more than a similar experiment showed, spent 20 years ago. This confirms the correctness geophysical models that say that the difference temperature between the solid core and the mantle above it should be at least 1,500 ° C, otherwise it is impossible to explain the existence of geomagnetic field. By the way, at the same time it was possible to establish why the authors of the previous study were mistaken. The core of the earth is mainly from a ball of liquid iron with a temperature of 4,000 ° C and “density” of more than 1.3 million atmospheres. In these conditions, it is so liquid that can be compared with water in the oceans. Only in the center of the planet where the pressure and temperature is even higher, iron goes into solid phase. Earthquake Analysis seismic waves passing through the Earth, allows to judge about the thickness of both nuclei and even how it grows with depth pressure. But these waves don’t say anything about temperature, which has a great influence on the movement of material inside the liquid core and a solid mantle above it. Moreover, it is the temperature difference between the mantle and the core is considered a major factor in large-scale thermal displacements, which together with the rotation of the Earth create something like a dynamo that generates the planet’s magnetic field. The temperature distribution inside the earth also underlies geophysical models explaining the occurrence and active volcanic activity in places like Hawaii or Reunion. The temperature in the center of the Earth can be determined by experiments with melting iron under different pressures: a diamond press allows compress tiny samples to several million atmospheres, then how a laser beam heats them up to 4-5 thousand degrees. Of course, describing it in two lines is much easier than doing it in laboratories: it is necessary to take care of the thermal insulation of the sample, so that he does not react with his environment, etc. Moreover iron can be heated to the temperature of the center of the earth only on a few seconds, and during this time it’s not so easy to understand the beginning it melt or not. Employees of the Nuclear Energy Commissariat France and the European accelerator complex ESRF in Grenoble (also France) have developed a new technology based on Intensive X-ray generated by the synchrotron: total in a second, its diffraction makes it possible to determine whether a solid sample is a liquid or partially melted. During this second you can hold temperature and pressure at a constant level, and also prevent the course of chemical reactions. Researchers brought temperature melting iron up to 4,800 ° C, and pressure up to 2.2 million atmospheres. The data were then extrapolated to find out the temperature at pressure of 3.3 million atmospheres, characteristic for the boundary between liquid and solid core, and found that it should be 6,000 ± 500 ° C. The value may turn out to be slightly different if the iron is experiencing unknown phase transition between measured and extrapolated indicators. So why Reinhard Böhler from the Chemical Institute Society them. Max Planck (Germany) and his colleagues in 1993 reported about another temperature – about a thousand degrees lower? The thing is starting at 2,400 ° C on the surface of the sample recrystallization, which leads to dynamic changes crystalline structure of solid iron. Twenty years ago scientists determined whether iron had melted or not, using the optical method, and it is possible that recrystallization was interpreted as melting. And so it looks in the ESRF laboratory. In depth frame hiding research co-author Guillaume Morar.
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