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Man-made boron-doped diamonds have been irradiated with energetic electrons. The effect of the dose, for irradiations performed around 15\ifmmode^\circ\else\textdegree\fi{}K, and the effect of the temperature (in the range 15-250\ifmmode^\circ\else\textdegree\fi{}K) upon the conductivity measured at 12\ifmmode^\circ\else\textdegree\fi{}K have been studied. Isochronal annealing, performed in the temperature range 15-350\ifmmode^\circ\else\textdegree\fi{}K, has shown the presence of several stages associated with the thermal release of carriers from traps and of a recovery stage around 260\ifmmode^\circ\else\textdegree\fi{}K. The activation energy for the recovery of the defect has been measured (1.3 eV) and the recovery kinetics determined. A level situated at about 20 meV below the conduction band has been associated with the defect. It is proposed that this recovery stage (around 260\ifmmode^\circ\else\textdegree\fi{}K) is due to the recombination of vacancy-interstitial pairs through the mobility of the interstitial.

Anelastic processes in Al single crystals present after low-temperature electron irradiation have been investigated using both internal-friction and elastic-aftereffect techniques. Several stress-induced relaxation processes have been observed, one due to the ${I}_{B}$ close-pair defect, and six others attributed to small interstitial clusters formed during long-range interstitial migration in recovery stage I. Details are presented concerning the creation, stability, symmetry, and relaxation kinetics of the various defects responsible for the anelastic processes. One of the processes exhibits all the characteristics expected for a configuration of the di-interstitial proposed by Johnson. A model is discussed which suggests how a small interstitial cluster may undergo reorientation without simultaneous migration of the defect center of mass.

A "geometrical" model is presented for the hexagonal close-packed lattice proposing several principal mechanisms for the displacement of a knocked-on atom. Using the experimentally determined resistivity-change rates of a previous paper and matching families of cross sections computed with this model, we have calculated sets of thresholds energies for displacement in the directions [0001], [10\ifmmode\bar\else\textasciimacron\fi{}14], [1012], [10\ifmmode\bar\else\textasciimacron\fi{}11], and [11\ifmmode\bar\else\textasciimacron\fi{}20] in cobalt, zinc, and cadmium. The correlation between the resistivity-change rates and the displacement cross sections allowed the determination of the Frenkel-pair resistivity per unit concentration in cobalt and zinc: ${\ensuremath{\rho}}_{F}^{\mathrm{Co}}\ensuremath{\approx}\frac{3{\ensuremath{\rho}}_{0\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}}^{\mathrm{Co}}}{\mathrm{at}.%}$, ${\ensuremath{\rho}}_{F}^{\mathrm{Zn}}\ensuremath{\approx}\frac{3.5{\ensuremath{\rho}}_{0\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}}^{\mathrm{Zn}}}{\mathrm{at}.%}$; no definite conclusion for ${\ensuremath{\rho}}_{F}^{\mathrm{Cd}}$ could be made owing to the proximity of a recovery stage. Expressions for the energies needed to pass across one or several open "windows" in the hcp unit cell were derived, including the possibility of focusing collisions in the [11\ifmmode\bar\else\textasciimacron\fi{}20] direction, and compared with the previously calculated threshold energies for displacement in various directions. This comparison permitted the tentative deduction of interatomic potentials of the Born-Mayer type giving as a possible choice: ${U}^{\mathrm{Co}}(\mathrm{eV})=3300{e}^{\ensuremath{-}4.1r(\AA{})}$, ${U}^{\mathrm{Zn}}(\mathrm{eV})=280{e}^{\ensuremath{-}2.5r(\AA{})}$, ${U}^{\mathrm{Cd}}(\mathrm{eV})=300{e}^{\ensuremath{-}2.0r(\AA{})}$.

Traps for hydrogen, attributed to defects at the surface of high-atomic-density Ne precipitates in Mo produced by 5.6\ifmmode\times\else\texttimes\fi{}${10}^{20}$, 9.4\ifmmode\times\else\texttimes\fi{}${10}^{20}$, and 3.1\ifmmode\times\else\texttimes\fi{}${10}^{21}$ 60-keV $^{22}\mathrm{Ne}^{+}$/${\mathrm{m}}^{2}$ have been studied in the temperature range 300\char21{}670 K by ion-beam techniques. A recovery stage was observed at 550 K equivalent to an activation energy of 1.5 eV, in good agreement with the known dissociation energy of hydrogen-vacancy complexes.