Fe^<57> Mossbauer Effect in Fe_2B, FeB and Fe_3C

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We have made measurements of Mossbauer effect of Fe^<57> in Fe_2B, FeB and Fe_3C to obtain some informatin on the situation of iron atom in these metallic compounds. Samples of Fe_2B and FeB were prepared by ordinary melting methods, while Fe_3C was obtained by electrolytic isolation from carbon steel. Samples were identified by X-ray and magnetic measurements, compared with results of former reporters. Mossbauer absorption spectra at room temperature are shown in Fig. 1. Observed values of internal field and isomer shift are listed in Table I, together whth Bohr magneton number of iron atom. As electronic configuration of transition metals in borides, carbides and nitrides can often be described by the donor theory, that B, C and N donate p-like electrons to metal atoms, iron atoms in Fe_2B, FeB and Fe_3C are also considered to have nearly 3d^8 or 3d^9 configuration. On the other hand, Walker's analysis indicates that the isomer shift will increase with increasing 3d and decreasing 4s electron numbers, ignoring a lattice dynamical contribution. Shirane et al. showed that this idea is considerably fit for a case of Fe_4N using results of neutron diffraction and isomer shift, which are shown on Table I. As expected, all of these compounds have positive isomer shift but the difference among them is little and does not depend on assumed 3d numbers.
社団法人日本物理学会の論文
1964-07-05