抄録
Mössbauer spectra and magnetic susceptibilities χ of the 1st and the 2nd stage FeCl2-graphite compounds are reported. The spectra at 80 and 300 K indicated that both stage compounds have two different Fe2+ ion sites (FeI and FeII) with dissimilar distortions from a regular octahedron of chlorines. Their spectra at 1.5 and 4.2 K were explained in terms of internal fields Hn along the c-axis at both sites and the temperature dependence of χ below 77 K was interpreted by weakly anisotropic triangular-layer ferromagnets with an effective spin S′=1. The obtained values of Hn, quadrupole splittings, isomer shifts and anisotropy of χ are discussed and compared with those of anhydrous FeCl2. The FeII site ions having the same crystal field as in the anhydride (with the doublet ground state) are presumed to induce spin polarizations of the FeI site ions (with the singlet one) along the c-axis via exchange fields.
