Low temperature Moessbauer spectra, electron transfer and spin density distribution in substituted magnetite

Moessbauer spectra of Zn, Ni and F substituted magnetite have been investigated at 75 and 7 K. Evidence for broad hyperfine field distributions due to substitutional disorder and fast electronic exchange has been found. At 7 K, for concentrations of Zn and Ni slightly above the critical concentration which suppresses the Verwey transition, a tendency has been observed for electron localization or local charge ordering to occur. (Auth.)