On the cation distribution in Ni1−xCuxFe2−yAlyO4 spinels

Abstract

Two spinel solid solution series, Ni1−xCuxFe2−yAlyO4 with y=0.6 and 1.0, where 0.0⩽x⩽1.0 have been investigated by x-ray diffractometry and Mössbauer spectroscopy. Lattice, hyperfine parameters, and cation distribution among the two distinct crystallographic sites as a function of Cu2+ and Al3+ substitution are determined. Mössbauer effect (ME) spectra at 293 K for compositions with y=0.6 consist of one sextet for A sites, and three sextets for B sites due to different fields at Fe nuclei. On the other hand, the ME spectra for the compounds with y=1.0 in the ferrimagnetic state at (293 and 77 K) show only one sextet for Fe3+ at A site giving clear evidence for a completely inverse spinel with Ni, Cu, and Al ions occupying B sites. ME parameters are deduced and analyzed for all studied compounds, where the observed hyperfine fields are explained on the basis of the superexchange and supertransferred hyperfine interactions.

Conductivity and dielectric studies of copper–aluminate substituted spinel nickel ferrite

“…This hopping mechanism is confined to the valence distribution of cations that occupy the oxygen octahedral site. For the present system Ni 1−x Cu x Al 0.6 Fe 1.4 O 4 where (0.0 ≤ x ≤ 1.0), Mössbauer results [9] showed that at x = 0.0 the Al 3+ ions occupy the octahedral sites while Ni 2+ occupy octahedral and tetrahedral sites as: (Ni 0 . 64 ].…”

“…Single-phase cubic spinel structure was confirmed by X-ray powder diffraction measurements. The details of the method of preparation were reported earlier [9]. Electrical measurements were carried for these samples by means of two probe method using complex impedance technique.…”

Mössbauer Effect Study of Copper Containing Nickel-Aluminate Ferrite

“…Such isomorphous substitutions in iron oxides are particularly apparent in their MoK ssbauer spectra, since these will drastically reduce magnetic interactions, resulting in lower magnetic ordering temperature and decreased magnetic "eld supertransfer (i.e., lower hyper"ne "elds) (3). Studies on aluminum magnetite Al V Fe \V O showed that Al> ions have a B-site preference (4,5). Also, studies of mixed nickel ferrites Ni}Cu show interesting results of cation distributions and magnetic properties (6).…”

Influence of V2O5 ion addition on the conductivity and grain growth of Ni–Zn–Cu ferrites

“…Ni 2+ and Cu +2 ions, having a favorable fit of charge distribution in the crystal field of octahedral sublattice [18,19], whereas Zn 2+ ions have preference for A-site due to their tendency to form covalent bonds involving sp 3 hybrid orbital [20]. D.O.M.…”