THE ELECTRICAL RESISTIVITY OF THERMOMETRICALLY PURE PLATINUM BELOW 11 °K

Abstract

A method is developed to obtain an interpolation of the resistance versus temperature function of pure platinum to an accuracy of about 0.01 °K in the range 4.2 to 10 °K, when calibration points below 4.2 and above 10 °K are available for a given sample. A study is made of the application of the two-band model to platinum in the range 1.5 to 11 °K. It is found that the accepted expressions for the ideal resistivity and for the Sondheimer–Wilson correction term do not describe the experimental results satisfactorily. Calculations of the ratio of the residual resistivity of band 2 to that of band 1, and of the ratio of the ideal resistivity of band 2 to that of band 1 indicate that electrons in the second band contribute significantly to the conductivity of platinum. A new expression for the ideal resistivity is proposed to account for the conductivity of the second bands