The EPR parameters D, g(parallel-to) and DELTAg (=g(parallel-to) - g(p
erpendicular-to)) for Ni2+ in an Al2O3 crystal have been studied by us
ing the high-order perturbation formulas and the parameters based on t
he optical absorption spectrum. From the study, one can find that to r
each a good fit between calculated and observed EPR parameters, the Ni
2+ ion is required to move 0.05 angstrom from the exact site of the re
placed Al3+ ion and to be closer to the midway plane between the oxyge
n layers. The reasonableness of this displacement is discussed.