Iron implantation in gadolinium gallium garnet studied by conversion-electron Mossbauer spectroscopy

Gadolinium gallium garnet single crystals were implanted with doses of Fe-57 ions in the range 8 x 10(15)-6 x 10(16) atoms cm(-2). Depending on the dose, iron with Fe2+ or Fe3+ charge states was found to have formed after the implantation. After a subsequent annealing in air, the iron oxidized to Fe3+. The Mossbauer and channelling measurements showed lattice recrystallization taking place at 600 degrees C. After recrystallization, the iron was found to have substituted for gallium ions both at the octahedral and at the tetrahedral positions. The relative concentration of the two types of iron at the two sites shifted towards the equilibrium distribution upon high-temperature annealing.