Thermoelectric Power in Silver-Gold and Silver-Germanium Alloys

The thermoelectric powers of dilute silver-gold and silver-germanium alloys are determined from 78 to 300°K. Nordheim-Gorter plots are made for these alloy systems at 273 and 295°K, and the characteristic thermopowers ${S_e}^1$ and ${S_e}^0$, due to solute and solvent, respectively, are determined at these temperatures. Calculated values of ${S_e}^1$, for both alloy systems, agree in sign and approximate numerical value with the experimental values. For Ag-Au, small or negligible Fermi-surface changes are indicated up to the maximum gold concentration of 1.5 at.%. The Ag-Ge data, however, deviate from the expected linearity predicted by the Nordheim-Gorter relation at approximately 0.5 at.%. A detailed comparison of the present Ag-Au data with previous results for Cu-Ag and Cu-Au is carried out, using a Nordheim-Gorter type relation for $\Delta S$, the difference in thermopower between the pure metal and alloy.