At higher pressures, LI is a superconductor
Search for substances that are superconductors at room temperature - one of the most important practical problems facing science. What is important is not only the desired result, but the approaches to it.
One of the candidates in the room-temperature superconductors - hydrogen, of course, not just hydrogen and hydrogen at high pressures. Little practical value hypothetical room- superconductivity of hydrogen obviously can not have, but other than purely scientific value of an experimental demonstration of a superconductor with a transition temperature to the superconducting state (Tc) of 300 K would be very important from a psychological point of view - it is one thing the theoretical possibility of the existence of materials with the desired characteristics, and quite another - that#39;s a feature.
A large number of theoretical calculations, whereby light chemical elements must be superconductors with high critical temperature Tc. To transfer to the superconducting state, these materials must be subjected to severe compression, in particular, the hydrogen estimates give the necessary znchenie pressure of 400 GPa. Such pressure is difficult to obtain in a laboratory, so the prediction of superconductivity of hydrogen are still only predictions.
But you can enjoy its neighbors in the periodic table of elements. The third element of the periodic table is lithium. In contrast, the hydrogen (which must first obtain a solid, which is in itself very difficult) Lithium metal is already at normal pressure. Therefore, it can be expected that the pressure required to transfer lithium to the superconducting state is significantly lower than for hydrogen.
However, the study of the electrical properties of lithium at high pressure prevents its high chemical activity: being placed in a diamond anvil cell to compress, lithium reacts with the diamond, and it does not work.
Recently, physicists at the University of Osaka and Tokyo has finally been experimentally shown that lithium under pressure becomes a superconductor. This occurs at pressures above 30 GPa at 48 GPa Tc is 20 K. This is the highest Tc for a simple one-element superconductors. It is fair to say that the conclusion that the superconductivity of lithium was made by Japanese scientists only on the basis of measurements of the temperature dependence of the resistivity. Due to technical difficulties they could not verify the existence of the Meissner effect.
However, the critical temperature measured decreases in the presence of a magnetic field (e.g., at a pressure of 34 GPa, the value of Tc falls to 8 in the absence of the field to zero in the T 3).
Thus, the theoretical predictions were correct for lithium, but whether they are true for hydrogen?
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