The low temperature electrical resistivity and thermoelectric power of palladium-platinum alloys

Abstract

The electrical resistivity and thermoelectric power of a number of PdPt alloys across the complete range of composition, have been measured as a function of temperature from 1 K to 100 K. The most distinctive feature of the measurements is that the low temperature characteristic thermopowers at the two ends of the alloy series have opposite signs. The concentration dependence of the residual resistivity is roughly parabolic in form, although the rate of increase of resistivity per atomic percent solute is twice as great at the palladium rich end. Both this, and the changing sign of the diffusion thermopower, is remarkably similar to the behaviour predicted for the NaK system on the basis of a pseudoatom model. Near the middle of the composition range there is a 30% decrease in ideal resistivity, which one can correlate with a very shallow resistance minimum in one of the concentrated alloys, and explain on the basis of a temperature dependent modification of the residual resistivity.