Vacancy concentrations in noncubic metals. Lattice constants of zinc

Measurements of the thermal expansion of the lattice parameters of Zn are combined with earlier measurements of the bulk expansion of oriented single-crystal bars to give a measure of the fraction of vacant lattice sites at temperatures near the melting point. The vacancy fraction at the melting point, η(Tₘ), is (3.0 ±{} 1.0) ×{} 10^-4, and the single-vacancy formation parameters are energy of formation Eᶠ=0.52±0.05 eV, and entropy of formation Sᶠ=(0.5±0.3)k. The strains associated with dislocation climb in response to changing vacancy concentrations favor dilation perpendicular to the c axis. A comparison is made of the principal-axis strains in noncubic metals as measured by thermal expansion and vacancy-flux electromigration methods.