Melting of transition metals at high pressure and the influence of liquid frustration: The early metals Ta and Mo

In this second report, we focus attention on the role that frustration plays in the melting curves of the early transition metals. Of particular interest are Mo and Ta. This is partly because these metals have nearly half-filled d bands implying that a maximum Jahn-Teller distortion is responsible for a high level of liquid frustration leading to melting slopes that are among the lowest observed for transition metals, and partly to resolve an apparent discrepancy between diamond-anvil cell and shockwave-melting measurements. Since the two sets of measurements are nonoverlapping, they are highly complementary, leading to a phase diagram for the two metals that resolves these discrepancies, without challenging the credibility of either set of measurements.