The residual resistivity of very dilute iron impurities in copper, and their precipitation by oxidation

✍ Scribed by Y. Yaeli; S. G. Lipson

• Book ID: 104627280
• Publisher: Springer US
• Year: 1976
• Tongue: English
• Weight: 554 KB
• Volume: 23
• Category: Article
• ISSN: 0022-2291
• DOI: 10.1007/bf00117244

✦ Synopsis

The residual resistance of high-purity copper can be greatly reduced if the metal is annealed in oxygen at a temperature just below its melting point. The effect is well known and has been used in many low-temperature investigations of the electronic properties of pure copper. We have carried out electrical and magnetic measurements which confirm that the effect is due to oxidation of residual Fe impurities in the copper, but in addition the formation of macroscopic particles of Fe304 is a necessary condition for success of the method. The macroscopic precipitation was discovered at Fe impurity levels down to 1 ppm. As a result of freezing out the contribution of Fe to the residual resistance, a minimum figure can be deduced for the resistivity contribution of free Fe impurities, and this figure is not in agreement with values deduced in earlier works. Resistance measurements were made with a superconducting galvanometer and magnetic measurements by the Faraday method.