COLOR-CENTERS, DISLOCATIONS AND COLLOIDS IN ION-IMPLANTED LIF AND LIF(MG)

Pure and magnesium-doped LiF crystals have been implanted with mainly magnesium and argon ions of 100 keV energy. Fluences were in the range of 6 x 10(15)-1 x 10(17) ions cm(-2). Changes in optical absorption during thermal annealing are reported. The magnesium colloid band at 280 nm and the lithium colloid band at 520 nm are identified. Some cases of anomalous colloid growth are observed. Hidden structural factors such as dislocations are thought to produce this anomalous annealing behaviour. Magnesium colloids develop in doped crystals after the implantation of rare gas ions. The responsible mechanism is thought to involve the interaction of F centres with impurity-vacancy (IV) dipoles. We find that the dopant has little effect on the concentration of F and F-2 colour centres or on their thermal stability in ion-implanted samples.