Positron annihilation measurement of the vacancy formation enthalpy in copper

Positron annihilation Doppler-broadening and lifetime data obtained for Cu in the temperature region of about 25-1040 degrees C are presented. The data were obtained by utilising a new 22 Na ion-implanted source-fabrication technique. The Doppler-broadening data were analysed using both a monovacancy and a monovacancy-divacancy two-state trapping model. For the monovacancy model a vacancy formation enthalpy of H 1v F =1.31+or-0.05 eV was deduced. A quantitative method for diagnosing the relative effect of each data point on the determination of H 1v F was introduced. The suitability of including divacancies in the analysis is also considered. The conclusion reached is that the measured formation enthalpy is indeed that for monovacancies.