Superconductivity and crystal structure of lithium under high pressure

Abstract

The superconductivity and structural properties of lithium under high pressure are investigated by simultaneous measurements of X-ray diffraction and electrical resistance at low temperature below 25 K. The structural transitions fcc - hR1 - cI16 near 40 GPa and the possible structural transition to higher pressure phases were observed above 70 GPa. The superconducting transition temperature Tc increases with applied pressure and has maximum in fcc phase. At higher pressures, Tc decreases in hR1 phase and increases again in cI16 phase. We did not observe Tc above 9 K for pressures above 70 GPa. Superconductivity possibly disappears in high pressure phases above 70 GPa.