Defect evolution was studied, as a function of annealing temperature, in monocrystals which had been grown in a H atmosphere and irradiated with 3.6 x 1017/cm2. Positron lifetime spectroscopic results were compared with infra-red absorption measurements. Vacancy-H, vacancy-2H, vacancy-O-H and di-vacancy complexes involving n atoms of H, where n ranged up to 6, were identified for the first time as being possible positron traps.

X.T.Meng, A.Zecca, R.S.Brusa: Applied Physics A, 1995, 60[1], 81-5