Melting of Sn at high pressure: comparisons with Pb.

Measurements for Sn, made using the laser-heated diamond cell, are reported that extend the melting curve to 68 GPa and 2300 K. Initially the melting temperature of Sn increases linearly with increasing pressure (dT/dP approximately 40 K/GPa) and near 38 GPa (2200 K) the melting curve flattens (dT/dP approximately 0), indicating a zero volume phase change at melting. The results are in good agreement with previously reported shock melting studies. In comparison to Sn the melting curve of Pb is relatively linear to 100 GPa, the highest pressure at which measurements have been made.

Melting of copper and nickel at high pressure: the role of d electrons.

Melting curves of Cu and Ni were measured in the laser-heated diamond cell to 97 GPa (3800 K) and 60 GPa (2970 K), respectively. The temperatures of Cu are in good agreement with recent theoretical calculations. The Cu melting slope (dT/dP) is about 2.5 times steeper than for Ni. The present results confirm the key role d-shell electrons play in determining the temperature dependence of high pressure melting curves in transition metals that have filled or partially filled d electron bands.