Preferential positron annihilation was studied by using a new Doppler broadening technique which involved a background reduction step that permitted the observation of positron annihilation with core electrons. Conventional positron lifetime spectroscopy was also used. Doppler spectra and positron lifetimes were measured for alloys across the entire concentration range of the Mg-Cd system. It was concluded that a small amount of preferential positron annihilation occurred at Mg sites. The temperature dependence of the peak counting-rate of the angular correlation curve was also determined for some samples, and the vacancy formation energies were deduced. In the case of 20at%Cd alloy, an increase in the peak counting-rate, which was characteristic of the generation of thermal vacancies, exhibited a discontinuity close to the order/disorder transition temperature.

Study of the Mg-Cd System by Positron Annihilation Methods E.Dryzek, J.Kuriplach, J.Dryzek: Journal of Physics - Condensed Matter, 1998, 10[29], 6573-84