The Residual and Temperature-Dependent Resistance of Reference-Grade Platinum Wire Below 13.8 K

We report the Residual Resistance Ratio (RRR) and resistance ratio W(GaMP) (gallium melting point) values for well-annealed samples of the original NIST platinum thermoelectric standard (SRM 1967), for its contemporary substitute SRM 1967a, and for a collection of NIST capsule-type SPRTs. The RRR dependence on annealing temperature is investigated and our results are compared with calculations based on contemporary chemical impurity analyses. The data are corrected to remove temperature-dependent components to derive the RRR at 0 K using W(T) data over the range 1 K<T<14 K to fit coefficients of an intrinsic function. Finally, we analyze the correlations in our RRR and W(GaMP) data and compare our contemporary data with other archival data from the literature.