No abstract

The melting curve of lithium between ambient pressure and 64 GPa is measured by detection of an abrupt change in its electrical resistivity at melting and by visual observation. Here we have used a quasi-four-point resistance measurement in a diamond anvil cell and measured the resistance of lithium as it goes through melting. The resistivity near melting exhibits a well documented sharp increase which allowed us to pinpoint the melting transition from ambient pressure to 64 GPa. Our data show that lithium melts clearly above 300 K in all pressure regions and its melting behavior adheres to the classical model. Moreover, we observed an abrupt increase in the slope of the melting curve around 10 GPa. The onset of this increase fits well to the linear extrapolation of the lower temperature bcc-fcc phase boundary.

We studied the pressure-induced superconductivity of BaLi4 up to 53 GPa by means of electrical resistivity in a diamond anvil cell. Superconductivity in BaLi4 is first observed at a pressure of 5.4 GPa with a superconducting critical temperature (Tc) of 4.5 K. Below 2 GPa, superconductivity is not observed above the minimum temperature achievable in the current study, 2 K. Between 5.4 and 12 GPa, the Tc increases steeply to its maximum value of 7 K. Above 12 GPa, the pressure dependence of Tc is complex and the sign of dTc/dP changes several times in going up to the maximum pressure studied, of 53 GPa.