Diamond has an unusually high Debye temperature

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

Solid State Physics, Ch Phonons: quantisation, occupation and inelastic scattering

Problem

Diamond has an unusually high Debye temperature, of order ΘD≈2200 K\Theta_D\approx2200\,\mathrm{K}, because carbon atoms are light and strongly bonded. ((a)) Estimate the zero-point energy per atom of diamond using the Debye evaluation Ezp=98kBΘDE_{\rm zp}=\tfrac98k_B\Theta_D. ((b)) Express this as a ratio to copper's zero-point energy of 33 meV33\,\mathrm{meV} per atom (ΘD=343 K\Theta_D=343\,\mathrm{K}), and comment in one sentence on why the two differ so much.

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