INVESTIGATION OF INTRINSIC POINT-DEFECTS IN METALS BY NUCLEAR-QUADRUPOLE DOUBLE-RESONANCE

The paper reviews the principal features of the Nuclear Quadrupole Dou ble Resonance (NQDOR) technique, with particular emphasis on its appli cation to the investigation of imperfections in cubic metals. NQDOR pe rmits measurements of the electric field gradients (EFG) at quadrupole -moment-carrying nuclei in the neighbourhood of point defects and thus to obtain ''fingerprints'' of these defects. An NQDOR facility set-up at the Max-Planck-Institut fur Metallforschung in Stuttgart is descri bed. It has been used to study the intrinsic defects introduced into C u and dilute Cu/Be alloys by low temperature irradiation with electron s or protons or by cold-work. It is shown that all well-resolved irrad iation-induced EFG observed in the present work are due to one kind of defect only, which is identified as the [100] dumbbell self-interstit ial. When considered together with measurements of the electrical resi stivity on the same specimens, the annealing behaviour of the NQDOR li nes supports the so-called two-interstitial model of radiation damage in face-centred cubic metals rather than the one-interstitial model.