Investigation of point defects in equilibrium concentrations with particular reference to positron annihilation techniques

Reviews the investigation of monovacancies and divacancies in or near thermal equilibrium at high temperatures. The use of positron annihilation for determining vacancy formation energies is covered in considerable detail and put into perspective relative to other methods (eg thermal expansion, self diffusion, nuclear magnetic resonance). The experimental techniques for studying the trapping of positrons at vacancies and the trapping model used for analysing the experimental results are reviewed. A detailed discussion in terms of ion core size valency, and vacancy relaxation is given of the trapping criteria for different metals. It is shown that the experimental results on the existence or nonexistence of positron trapping by vacancies are well accounted for by the theoretical ideas. The formation energies of monovacancies in metals obtained by the positron annihilation techniques are presented and compared with those obtained by other methods.