Amorphization of yttrium iron garnet (YIG)Y3Fe5O12 induced by the irradiation of 960 MeV Ar ions at 195±0.1K has been investigated by means of the sample-tilting X-ray diffraction(STD) and the saturation magnetization measurement. It is indicated that the transformation of crystalline tO amorphous state is a gradual process in which the electronic stopping power S. plays a dominant role
and a certain dose is necessary. A nearly complete amorphous state was observed at Se= 8.3MeV/μ m.