Effect of High Pressure on the Thermoelectric Power and Electrical Resistance of Aluminum and Gold

Abstract

The effect of pressure up to 4 kbar on the thermoelectric power of aluminum, gold, nickel, and platinum has been determined. The change in resistance with pressure of aluminum and gold has also been measured. Measurements were carried out at temperatures between room temperature and 1300°K or, in the case of aluminum, between room temperature and 900°K. The high-temperature thermoelectric-power data for aluminum are separated into terms associated with three thermally activated defects: the monovacancy, the divancy, and the impurity-vacancy pair. Values for the formation energy and volume are obtained for each of these defects. The effect of vacancies in gold is dominated by the effect of pressure on the lattice so that no quantitative results can be determined. An effect consistent with a monovacancy model is detected. Measurements in platinum and nickel were carried out to test the sensitivity of the method to changes in scattering mechanism. A phenomenological model is presented to explain the resistance data in aluminum and gold. This model gives the accepted formation volume for monovacancies in gold. It gives a value for the formation volume of monovacancies in aluminum in agreement with the value obtained from thermoelectric-power measurements. The presence of divacancies in aluminum is strongly supported by this model.