Positron states for the bulk and vacancy in intermetallic compounds crystallizing in the B2 structure were calculated by using DV-Xα electronic structure calculations, and were compared with experimental results. The calculated positron lifetime at the Ti vacancy was found to be longer than that at the Co vacancy. Charge transfer from Ti to Co led to a difference in the localization of the positron wave function at the vacancy. At the Co vacancy site surrounded by positively charged Ti atoms, the positron wave function did not localize as well as at the Ti vacancy site; which decreased the positron lifetime. The calculated results suggested that the positron lifetimes in intermetallic compounds could not be directly correlated with those of the pure component, and that charge transfer between the constituent atoms affected localization of the positron wave function.

Theoretical Calculation of Positron Lifetimes in CoAl and CoTi. M.Mizuno, H.Araki, Y.Shirai: Materials Transactions, 2002, 43[7], 1451-5