It is tempting to argue that a solid should always conduct heat better when it is hotter

PHYSICS · Subjective · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Lattice dynamics and thermal properties of solids · Lattice dynamics and thermal properties of solids

Condensed Matter Physics, Ch Thermal expansion and lattice thermal conductivity

Problem

It is tempting to argue that a solid should always conduct heat better when it is hotter, because more thermal energy is available to be carried. Rock salt's measured lattice conductivity at 300 K300\,\mathrm{K} is κ=6.4 W m−1K−1\kappa = 6.4\,\mathrm{W\,m^{-1}K^{-1}}, and its Debye temperature is ΘD=321 K\Theta_D = 321\,\mathrm{K}. Is this right? Estimate κ\kappa at 600 K600\,\mathrm{K} and say whether it is larger or smaller than at 300 K300\,\mathrm{K}.

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