Quenching of lattice vacancies in pure silver

Two mil diameter 99.998% pure silver wires were quenched. Special efforts were made to keep the specimen pure. The energy required to form a lattice vacancy was found to be 1.10 ± 0.04 ev. The activation energy for motion of a lattice vacancy was found to be 0.83 ± 0.05 ev. These results indicate that self-diffusion in pure silver occurs mainly by the vacancy mechanism. The data of Simmons and Balluffi, who obtained the vacancy concentration in equilibrium near the melting point, together with the present data give the resistivity increase per atomic per cent vacancies to be 1.3 ± 0.7 micro ohm cm if most of the voids are divacancies. The following tentative conclusions are drawn. Most of the Quenched-in defects consist of divacancies if specimens are quenched above 600°C. The annealing kinetics below 0°C are second order indicating that divacancies combine to form quadrivacancies. The activation energy for motion. of a divacancy is 0.57 ± 0.03 ev. Below 0°C two divacancies combine when the meet, forming a quadrivacancy. The indications are that a quadrivacancy is much less mobile than a single vacancy or a divacancy. The immobile vacancy clusters can absorb more divacancies thus forming large clusters. The binding energy of a quadrivacancy is between 0.22 ev and 0.38 ev. The annealing half time is about 4 seconds at 90.3°C. Above 90°C a freshly quenched specimen anneals by motion of divacancies to dislocations. Pulsing experiments give 0.34 ± 0.05 ev as the binding energy of a divacancy. A divacancy can be broken up into two single vacancies by heating at 270°C for 0.09 seconds.published or submitted for publicationU of I Onlythesi