Mössbauer Studies of Radiation Damage in Magnetite

Radiation damages in Fe₃O₄ magnetite crystal caused by implantation of Fe ions with an energy of 5.6 MeV and a fluence of 10¹⁴ cm^–2 was studied by two methods of Mössbauer spectroscopy: conversion Mössbauer spectroscopy with registration of conversion electrons from a depth of up to 0.5 μm and X-ray Mössbauer spectroscopy with registration of secondary X-ray radiation from a depth of up to 35 μm. The samples were Fe₃O₄ single crystal tablets with a diameter of 10 mm. The data for irradiated and non-irradiated samples were compared. All Mössbauer spectra contained two sixtets corresponding to crystallographic positions A and B in magnetite. The parameters of the sixtets corresponded to the literature data. The widths of the Mössbauer lines were small and were in the range of G = 0.3–0.4 mm/s. Irradiation with Fe ions did not cause noticeable damage in the crystal lattice. In the case of the irradiated sample, an additional FeO_x phase with an intensity of 10% was detected using conversion Mössbauer spectroscopy method with an effective depth of 0.5 μm. The experimental data were considered based on the thermal spike model. The formation of the FeO_х phase is possible as a result of quenching after overheating in the track area.