= Solution
In the cold solid, <phonon scattering> makes $\tau\propto T^{-1}$ and therefore conductivity falls as <temperature> rises, at roughly fixed <carrier density>. After melting and ionization, the character of scattering changes; a hot Coulomb <plasma (physics)>[plasma] eventually follows an increasing $T^{3/2}$ branch. A minimum in the crossover region is natural, but a weakly coupled <plasma (physics)>[plasma] formula is not quantitatively justified throughout the warm dense regime.
Back to article page
