Deviations from Matthiessen's Rule for Platinum

Abstract

An analysis of the resistivity-temperature relationship down to liquid helium temperatures of 17 platinum resistors as determined in various laboratories shows that deviations from Matthiessen's rule can be classed roughly into three groups. One of them follows the pattern predicted by Sondheimer and Wilson's theory. The other two cannot be fully explained in this way, and may be due to the sensitivity of the electronic band structure of transition metals to small concentrations of impurities. The behaviour of a resistor thus depends on the nature as well as the total amount of impurities and imperfection~. In low temperature platinum resistance thermometry the resistors should be selected with regard to the type of residual impurity as well as total impurity content.