A study of a number of mixed transition metal oxide spinels using X-ray photoelectron spectroscopy
1989; Elsevier BV; Volume: 37; Issue: 1 Linguagem: Inglês
10.1016/0169-4332(89)90977-x
ISSN1873-5584
AutoresG. C. Allen, Steven J. Harris, J.A. Jutson, John M. Dyke,
Tópico(s)Magnetic Properties and Synthesis of Ferrites
ResumoX-ray photoelectron spectra have been recorded from 5 series of characterised iron-chromium containing spinels. MnFexCr2−xO4, Mn1−xFexCr2O4, FexCr3−xO4, CoFexCr2−xO4 and NiFexCr2−xO4. Mn 2p32 peak binding energies in the range of 640.0 to 641.3 eV were recorded from samples taken from both series of manganese spinels. Significant changes were noted in the Ni2p photoelectron spectra and attributed to the displacement of the nickel(II) cation from octahedral to tetrahedral lattice positions. These changes included large shifts in the Ni2p32 peak binding energy plus intensity and positional changes in the associated satellite structure. Shifts were also observed in the Cr2p spectra which were related to the variation in sample composition. These shifts followed two distinct trends. For the manganese, iron, nickel spinels: [Mn, Fe, Ni]Cr2O4 < Cr2O3 < [Mn, Fe, Ni][Fe, Cr]2O4, For the cobalt spinels: Co[Fe, Cr]2O4 ≤ Cr2O3 < CoCr2O4. Quantitative XPS analysis identified the surface segregation of chromium ions during the preparation of cobalt spinels and the segregation of both iron and chromium in the nickel containing compounds.
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