Measuring residual resistivity ratio of high-purity Nb

Published

July 27, 2004

Author(s)

Loren F. Goodrich, Theodore C. Stauffer, Jolene Splett, Dominic F. Vecchia

Abstract

We compared methods of measuring the residual resistivity ratio (RRR) of high-purity Nb using transport current. Our experimental study is intended to answer some fundamental questions about the best measurement for RRR and the biases that may exist among different measurement methods, model equations, and magnetic field orientations. Two common ways to obtain the extrapolated normal-state resistivity at 4.2 K are (1) measure the normal-state resistivity as a function of field at 4.2 K and extrapolate to zero field and (2) measure the normal-state resistivity as a function of temperature in zero field and extrapolate to 4.2 K. Both approaches have their associated difficulties. We also compared data taken with the magnetic field both parallel and transverse to the specimen current and we measured magnetoresistance at various temperatures from 4 to 16 K. We combined all of these data to estimate the RRR using an approach based on the Kohler empirical rule regarding magnetoresistance. The Kohler rule imposes the shape of the magnetoresistance curve at the higher temperatures to better predict the extrapolated normal-state values at the lower temperatures.

Proceedings Title

Advances in Cryogenic Engineering

Volume

50

Conference Dates

September 23-26, 2003

Conference Location

Anchorage, AK, USA

Conference Title

International Cryogenic Materials Conference (ICMC)

Pub Type

Conferences

Keywords

compare, extrapolation, field orientations, high-purity Nb, methods, residual resistivity ratio, superconductor, variable temperature

Citation

Goodrich, L. , Stauffer, T. , Splett, J. and Vecchia, D. (2004), Measuring residual resistivity ratio of high-purity Nb, Advances in Cryogenic Engineering, Anchorage, AK, USA (Accessed December 3, 2024)