RADIATION-DAMAGE OF ALPHA-AI2O3 IN THE HVEM .1. TEMPERATURE-DEPENDENCE OF THE DISPLACEMENT THRESHOLD

The temperature dependence of the apparent displacement threshold energy has been measured for single crystal α-Al2O3 in a high voltage electron microscope, over the temperature range 320-1120 K. Below 570 K the threshold energy for observable damage remains constant at 390 ± 10 keV, then rises to a peak of 440 ± 20 keV at 695 K followed by a rapid fall to ~200 keV at 870 K and above. Measurement of the displacement threshold energy, using the optical absorption and luminescence of oxygen and aluminium electron irradiation induced vacancies at several temperatures, gives a value of 440 ± 25 keV for the oxygen ion and 175 ± 25 keV for the aluminium ion. These results show that oxygen and aluminium ions have widely different displacement energies, Ed, of ~75 and 18 eV respectively. © 1979.