Recently, research team of Center for Energy Matter in Extreme Environments from Institute of solid State Physics, Hefei Institutes of Physical Science, together with Prof. Federico Aiace Gorelli from Istituto Nazionale di Ottica, made a new progress in hydride.
In their work published online in PHYSICAL REVIEW B, a kind of selenium trihydride is synthesized at high pressures.
A new record at high superconducting transition temperature (Tc) up to 203 K has been reported in the H-S system at 150 GPa. Se is adjacent and isoelectronic to S in the periodic table. It would be plausible to expect that selenium hydrides could also demonstrate high-Tc superconductivity.
Previously, two independent theoretical studies make sure that selenium hydrides exhibit high Tc in the range of 40–131 K at megabar pressures. These predictions are still awaiting experimental confirmation, and synthesis is the first thing.
In the joint work, researchers demonstrate the successful synthesis of selenium trihydride with Cccm structure at pressures as low as 4.6 GPa and show its structural stability (probed with XRD) up to 40 GPa if compressed at low temperatures.
Moreover, a possible metallization is observed at 23 GPa. The changes in properties of this material with pressure are very much in line with the behavior of Cccm H3S.
The results suggest that the H-Se system may be promising for reaching high-Tc superconductors at lower pressures than in the H-S system.
Microphotographs of the DAC cavities at elevated pressures demonstrating the formation of H-Se compounds. (a) Solid H2Se is grown (circled). (b) Cccm H3Se is grown pictured as a bar in the middle of the cavity. (c) Supposedly a metallic H3Se is formed; the crystal bridged the cavity sides and deformed. It reflects light in the areas where the surface is perpendicular to the optical axis and is dark (nontransparent for the transmitted light) where it is tilted. (Image by ZHANG Xiao)
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