TEMPERATURE-DEPENDENCE OF ELECTRICAL-RESISTIVITY OF PURE IRON AT LOW-TEMPERATURES

Experimental data in the temperature range from 1. 6 K to room temperature can be expressed by a simple sum of the phonon scattering term, a term proportional to T**2 and residual resistivity. The phonon scattering term is estimated by the Gruneisen-formula. The coefficient of the T**2 term is (2. 2 plus or minus 0. 1) multiplied by 10** minus **1**1 ( OMEGA multiplied by (times) cm multiplied by (times) deg** minus **2) and the term proportional to T is negligibly small. A new index, RRR//H//,**O//K, is suggested as an appropriate measure of purity for highly purified iron, and the largest value of RRR//H//,//O//K obtained is 20210 on the sample with RRR//H//,//4//. //2//K 11390.