Absence of superconductivity in LiPdH_x

Abstract

Theoretical calculations about LiPdH predict that it may be a superconductor. Using the high-pressure synthesis technique up to 3 GPa, we have successfully fabricated the LiPdH compound. The sample looks quite pure judging from the refinement of the X-ray diffraction pattern. However, no superconductivity has been detected down to about 2 K. The specific heat measurement shows a small Sommerfeld constant = 1.22 mJ mol K, which is a bit smaller than the theoretically predicted value. The magnetic susceptibility measured at 1 Tesla reveals a Curie–Weiss law behaviour in the low-temperature region with an estimate of the magnetic moment of 0.08 /Pd. The temperature dependence of resistivity has also been measured up to 25.2 GPa, but superconductivity is still not observed above 2 K. The large residual resistivity and small residual-resistivity ratio suggest that the quasiparticle scattering by impurities is quite strong, which might be induced by the hydrogen deficiency, and intimately hinders the occurrence of superconductivity in LiPdH.

Keywords:

• LiPdH
• high pressure
• specific heat
• hydrogen
• superconductivity

Notes

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Ministry of Science and Technology of China [grant number 2016YFA0300401], [grant number 2016YFA0401704], and the National Natural Science Foundation of China (NSFC) with the [project number A0402/11534005], [project number A0402/11674164], [project number E0211/51302133].