Resistivity of Very Pure Th and Th—Rare-Earth Alloys

Abstract

Resistivity data are given for pure thorium samples with a resistivity ratio [$\ensuremath{\Gamma}=\frac{{{{\ensuremath{\rho}}_{300}}^{\ensuremath{\circ}}}_{\mathrm{K}}}{{{{\ensuremath{\rho}}_{4.2}}^{\ensuremath{\circ}}}_{\mathrm{K}}}$] greater than 1000. At high temperatures, deviations of the resistivity from the Block-Gr\"uneisen relation correspond closely to the anomaly which is found in the specific heat. The resistivity at 300\ifmmode^\circ\else\textdegree\fi{}K is found to be 15.8 \ensuremath{\mu}\ensuremath{\Omega}-cm. Thorium---rare-earth alloys show no resistance minimum of the type discussed by Kondo, to an accuracy of 0.001 \ensuremath{\mu}\ensuremath{\Omega} cm.