Thermoelectric Power of Lattice Vacancies in Gold

The change $\Delta S$ of the thermoelectric power of high-purity gold wires due to quenched-in lattice vacancies was measured between 4.2 and 220°K. The vacancy concentration was determined from the quenched-in electrical resistance at 4.2°K. From the value of $\Delta S$ at 200°K, where phonon-drag effects are negligible, the electronic part $\Delta S_e$ of $\Delta S$ was calculated as a function of the temperature, using the Friedel theory. The phonon-drag part $\Delta S_g$ was obtained from the equation $\Delta S_g=\Delta S-\Delta S_e$. Vacancies were found to cause a reduction of the electronic part and of the phonon-drag part of the thermoelectric power. $\left|\Delta S_e\right|$ and $\left|\Delta S_g\right|$ reach a maximum at low temperatures. The phonon-scattering cross section of vacancies, as estimated from $\Delta S_g$ assuming a pure Rayleigh-type scattering mechanism, indicates that phonons are scattered by vacancies predominantly through the strain field associated with the vacant lattice site.