Aluminium contributes three conduction electrons per atom

PHYSICS · Multi-part · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Free electrons, energy bands and electronic structure · Free electrons, energy bands and electronic structure

Solid State Physics, Ch The degenerate electron gas, finished

Problem

Aluminium contributes three conduction electrons per atom, giving electron density n=1.81×1029 m−3n=1.81\times10^{29}\,\mathrm{m^{-3}} and Fermi energy EF=11.7 eVE_F=11.7\,\mathrm{eV}. Its measured bulk modulus is 76 GPa76\,\mathrm{GPa}. ((a)) Estimate the T=0T=0 degeneracy pressure of the conduction electrons, P=25nEFP=\tfrac25nE_F. ((b)) Estimate the corresponding degeneracy bulk modulus B=23nEFB=\tfrac23nE_F. ((c)) Compare the estimate with the measured bulk modulus, quoting the ratio, and comment on what the comparison shows.

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