Metallic hydrogen

Metallic hydrogen, which is under pressure of the order of four and a half million atmospheres, can have the highest critical temperature of the transition in a series of high-temperature conductors. According to preliminary calculations by the Italian-German group of theoretical physicists, the critical temperature of the element is 242 K (minus thirty-one degrees Celsius).

Hydrogen gas is converted to a liquid at a temperature of 20 K. If the temperature is lowered by another 6 K, it is possible to transfer the element to a solid state. Hanington and Wigner in 1935 suggested the production of hydrogen in the laboratory. In their opinion, it was necessary to use high pressure - about 25 GPa (one GPa is approximately equal to ten thousand atmospheres). Thus, under the influence of high pressure, the element becomes an isotope of hydrogen - from the dielectric element to the conductive element. It should be noted that the gas in the initial state has conductive properties. Just like metals, the element conducts electricity, and it may not be in a solid state. In other words, hydrogen can also be a liquid with metallic properties.

In 1971, the work of Soviet theoretical scientists led by Kagan was published. A group of physicists have argued that metallic hydrogen can be metastable. This means that after the cessation of exposure to increased pressure, the element will not go to its original state - a gas that has dielectric properties. Along with this, it is still unclear whether this stage will be long enough to have time to use metallic hydrogen.

The first success in the pilot plan was received in 1975, in February. A group of scientists led by Vereshchagin created metallic hydrogen. Under the effect of a temperature of 4.2 K in a thin layer of the element, a decrease in the electrical resistance of the gas by a million times was also observed with diamond anvils subjected also to a pressure of the order of 300 GPa. This indicated the transition of hydrogen to a metallic state.

To obtain high pressure, a diamond anvil is used. It is represented in the form of two artificial diamonds, the points pressing against each other with the help of a press. As a result, on the cut, whose diameter is of the order of a few tenths of a millimeter, the necessary pressure is formed. A cooled sample is located in this cell in the cell. To the sample in the same place the equipment is brought: miniature thermocouples, electrodes and other measuring devices.

The next stage in the work of scientists was to elucidate the possibility of a subsequent transition of the metallic state to the superconducting state. The first to ask this problem was Neil Ashcroft. The theoretician predicted that "metallic" hydrogen would have "exotic" properties under the influence of high temperatures exceeding 200 K.

More recently, the work of German and Italian physicists was published. The authors state that due to the electron-phonon mechanism for the formation of Cooper pairs, a record critical temperature of 242 K is reached. Along with this, however, high-pressure action is necessary - about 450 GPa, and this, in turn, is four and a half million Times the atmospheric pressure.

In the case of electron-phonon formation of Cooper pairs during motion in a periodic lattice in a crystal, the electron attracts the nearest ions charged positively. In this case, there is an insignificant deformation of the lattice, and for a short time the concentration of the positive charge increases. Due to the increased concentration, another electron is attracted. So, both electrons are attracted. At a nonzero temperature, the ions vibrate near their equilibrium states. Phonons are quanta of the data of oscillations.