The structure and electronic transport properties of the chalcogen elements under hydrogen pressure to 180 GPa were measured. The enhanced superconductivity values for Se were obtained and on the verge of the β-Po–bcc phase transition, up to 9.4 K at 140 GPa. The superconducting transition is evidenced by a direct zero resistance drop and was further verified through its suppression under an external magnetic field with μ0Hc0=0.26 T at 140 GPa. An abnormally high resistance peak preceding the drop to zero resistance exhibits granular superconductivity. Our studies demonstrate that selenium does not react with hydrogen at 182 GPa at room temperature or 102 GPa with laser heating to 3000 K, suggesting that the synthesis of selenium hydride requires higher energy conditions than the ones suggested in theoretical predictions. The results of structural evolvements of Te under hydrogen will be also presented. The recent results of LK-9 will be also presented.
 

Transition metal dichalcogenides,high pressure,Se,Te,Superconducitivity