Formation and migration energies of vacancies in copper

Abstract

The fraction of the electrical resistivity of quenched copper which is often attributed to vacancy defects may include relatively large contributions due to occluded hydrogen and oxygen. Oxygen contamination can be prevented by adding carbon monoxide to pre-quench atmospheres of nitrogen and argon. The resistivity due to hydrogen contamination can be eliminated by a suitable annealing procedure. When such precautions are observed, the quenching method yields the value (1·14±0·06) ev for the formation energy of single vacancies in copper. Isochronal annealing of quenched copper at temperatures progressively increasing from 0°c reveals three recovery stages. From a comparison with the results of previous investigations for quenched and cold-worked noble metals, the defect stages, in order of increasing temperature, are ascribed to divacancies, single vacancies and larger vacancy aggregates, respectively. The following estimates of the ratios of migration energy to order of kinetics were derived from the isochronal curve: stage 1, (0·74±0·13) ev, stage 2, (0·85±0·15) ev, stage 3, (0·67±0·14) ev. The ratio for stage 1 is confirmed by isothermal annealing which indicates 1st order kinetics and a migration energy of (0·71±0·04) ev for divacancies.