The trapping of positrons at vacancy sites in some metals provides a new and sensitive method for the equilibrium determination of vacancy-formation energies. Data are presented for Al, Cd, In, Pb, and Zn and fitted to a model allowing presentation in the form of Arrhenius plots. The vacancy concentration is not determined because it appears as a product with the positron trapping rate.

• Received 26 October 1971

DOI:https://doi.org/10.1103/PhysRevLett.28.358