Thermoelectric Power of Vacancies in Aluminum

Abstract

The thermoelectric potential difference between a well-annealed aluminum wire and a quenched aluminum wire has been measured as a function of temperature from 4 to 150 \ifmmode^\circ\else\textdegree\fi{}K. Measurements were made for several quench temperatures and for a distilled ice and water quench followed by rapid insertion into a dry ice and methanol medium. These data were used to determine the effect of vacancies on the thermopower of aluminum. The thermopower is enhanced by vacancies at temperatures below about 70 \ifmmode^\circ\else\textdegree\fi{}K and reduced at higher temperatures. It is proposed that the enhancement is due to the change in electron-diffusion thermopower. A calculation of this effect has been made based on the theory of Nielsen and Taylor, and the agreement with the experimental results is striking. The reduction in thermopower above 70 \ifmmode^\circ\else\textdegree\fi{}K is explained by the change is the phonon-drag thermopower due to vacancies. The Rayleigh-scattering parameter was determined from the experimental data and is compared to calculated values using the theories of Klemens and Carruthers.