CONVERSION ELECTRON MOSSBAUER SPECTROSCOPIC STUDY OF ION-BEAM MIXING AT Fe-Mo INTERFACE.

Ion beam induced atomic mixing at Fe-Mo interface has been studied by using the technique of conversion electron Mossbauer spectroscopy (CEMS). A noninterface sensitive measurement has also been performed to reveal the magnetic hyperfine interactions in the entire region of the iron overlayer. It is shown that a deposition induced reaction between the molybdenum substrate (having a thin coating of native oxide) and the Fe**5**7 layer renders a graded nature to the interface, which is transformed upon ion bombardment (100-keV Kr** plus , dose approx. 10**1**6 ions/cm**2) into a disordered alloy. The dominant nonmagnetic component corresponding to the interface of the ion beam mixed sample happens to be a quadrupole doublet, which represents the presence of Fe**5**7 atoms in Fe**2** plus charge state. It is shown that the oxygen-incorporated regions of the disordered alloy retain the nonmagnetic Fe**2** plus charge state subsequent to annealing at 500 degree C, while other regions lead to precipitation of alpha -Fe and Fe//2Mo phases.