The Residual Resistance Ratio of High-Purity Platinum

Published

August 22, 2011

Author(s)

Weston L. Tew, William E. Murdock, Michal J. Chojnacky, Dean C. Ripple

Abstract

High-purity platinum wire is produced for use in both Standard Platinum Resistance Thermometers (SPRTs) and type S and type R thermocouples. The resistance ratio W(T90) and thermoelectric characteristics of the wire are a function of chemical purity and physical strain, and the characteristics of a given specimen can be compared to those of Standard Reference Material (SRM) 1967. A commonly reported resistance ratio which is highly sensitive (i.e. most readily observable) to impurity and strain is the so-called residual resistance ratio X_RR or R(273.15 K)/R(4.2 K). We present data in terms of X_RR and W(T90) from well-annealed Pt samples of the original SRM 1967, its contemporary substitute SRM 1967a, and a collection of NIST capsule-type SPRTs. We analyze the correlations in our resistance ratio data and compare our contemporary data with historical data from the literature.

Conference Dates

August 22-25, 2011

Conference Location

National Harbor, MD

Conference Title

National Conference of Standards Laboratories International 2011

Pub Type

Conferences

Keywords

Residual Resistance Ratio, platinum, high-purity, temperature, resistance thermometry, ITS-90, resistivity

Citation

Tew, W. , Murdock, W. , Chojnacky, M. and Ripple, D. (2011), The Residual Resistance Ratio of High-Purity Platinum, National Conference of Standards Laboratories International 2011, National Harbor, MD (Accessed October 9, 2025)