In order to investigate the basic properties of radiation-induced defects in oxide crystals, positron annihilation lifetime and Doppler-broadening measurements were performed on crystals which had been sintered (1200C, 18h) and irradiated with 1MeV electrons at 4K and 3MeV protons at 23K. After electron irradiation, the positron lifetime and Doppler-S parameter decreased slightly. After proton irradiation, both the lifetime and the S-parameter markedly increased. Isochronal annealing revealed annealing stages at about 150, 500 to 550 and 750C. These stages were attributed to the annealing of vacancy complexes with various sizes.

Studies of Defects in Electron and Proton Irradiated ZnO by Positron Annihilation. Puff, W., Brunner, S., Mascher, P., Balogh, A.G.: Materials Science Forum, 1995, 196-201, 333-8