抄録
Mössbauer spectra of RFe2O4 (R=Y, Ho, Er, Tm or Yb) were measured between 200 and 500 K, in the paramagnetic region. Amalgamation, from two quadrupole doublets due to different ionic states of Fe into one doublet, was observed and successfully analysed by a stochastic theory, except the stoichiometric Y and Er compound. In the latter case, in which Verwey transition takes place at low temperature, the analysis failed because of the existence of other set of absorptions. When the stochastic theory was applicable, seven parameters were deduced at each temperature: isomer shift, quadrupole splitting and width for both states of Fe and the frequency of the fluctuation. It is concluded that Fe atoms fluctuate between two ionic states, neither 2+ nor 3+ in its literal meaning but mixtures of them: itinerant model is more appropriate than the ionic model for 3d electrons of iron in these oxides.
