On the behaviour of low temperature irradiated cadmium

Abstract

The atomic displacement process in electron irradiated cadmium has been studied. The experimental data can be fitted using an energetic threshold for Frenkel pair formation T_d , = 19 eV. Discussion of the nonlinearity of the resistivity increase per electron versus total electron flux shows that this behaviour may be explained by the existence of a very unstable Frenkel pair specie, the mutual annihilation of which may be initiated either thermally at ∼5.5 °K after the irradiation, or dynamically. In the latter case, the most important events for producing pair annihilation would be elastic interactions of secondary electrons with the atomic nuclei. With regard to the high c/a ratio in cadmium, clues exist showing that these unstable defects are likely to be Frenkel pairs situated in and interacting through densely packed atomic rows in the basal planes.