Metal hydrides at high pressure
Room-temperature superconductivity is one of the most attractive but very difficult research areas in nowadays solid-state physics due to its both theoretical and experimental complexity. Pressure is the thermodynamic variable, which plays an important role in modifying physical properties of substances, and recently very high-temperature superconductivity (TC > 200 K) was reported at high pressure in hydrogen-rich materials.
Yttrium hydrides seem to be very promising candidates to new superconductors with TC close to room temperature, as the valence electron state of Y enables its bonding with a large number of hydrogen atoms and the formation of hydrogen-rich materials. The high-pressure high-temperature (HPHT) synthesis of yttrium hydrides using various hydrogen sources leads, however, to formation of numerous previously unknown phases that prevents one from identifying exactly the phase possessing superconducting properties. Thus, studying the effect of the hydrogen source (in this research a hydrogen gas, paraffin oil and ammonia borane) on the HPHT synthesis products is very important and can help to solve the problem of the targeted synthesis of room-temperature superconductors. We develop new approaches to the synthesis and studying of superconducting materials focusing on HP single-crystal X-ray diffraction on multigrain samples, theoretical calculations, and on application of 1H-NMR to hydrogen-rich metal hydrides, in particular yttrium hydrides, to detect the phenomenon of superconductivity at high pressure.