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Positron annihilation Doppler-broadening and lifetime data obtained for Cu in the temperature region of about 25-1040 "C are presented. The data were obtained by utilising a new 22Na 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:, = 1.31 0.05 eV was deduced. A quantitative method for diagnosing the relative effect of each data point on the determination of H:, 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.

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