Vir,ain MgO (110) single crystals have been implanted with 30 keV He-3(+) i
ons to a dose of 5x10(15) cm(-2). After implantation the samples have been
annealed under air for 30 min in a tube oven. The annealing behaviour of th
e defects and He-3 has been monitored by three experimental techniques: pos
itron beam Doppler broadening, neutron depth profiling (NDP) and optical ab
sorption in the UV to near-IR region. The observations in MgO lead to the c
onclusion that below 1000 degrees C the vacancy like defects are stabilised
by the implanted He atoms. Above this temperature He may dissociate from t
hese small defects, allowing the formation of larger vacancy clusters. (C)
1999 Elsevier Science B.V. All rights reserved.