LXXXIII. Quenching vacancies in platinum

Abstract

The electrical resistance of platinum wires was measured in liquid nitrogen before and after heating to high temperatures and quenching to room temperatures. It was found that the resistance after quenching was greater than its original value but that the increase could be removed by annealing at temperatures in the region of 400°c. This annealable increase is interpreted as being due to lattice vacancies. The whole annealing process was governed by an activation energy of 1·1 ev and this energy is considered to be that for movement of a single vacancy. It is deduced that a vacancy made on average 10⁹ jumps before disappearing. The annealing results are used to show that in certain cases quenching was fast enough to retain the high temperature equilibrium concentration of vacancies. Hence the variation of increase of resistance on quenching with initial temperature is used to deduce an energy of 1·4 ev for forming a vacancy. The entropy factor required does not disagree with theory.