This work investigates the charge transfer and Al(Ga) p-Ni d hybridization effects in the intermetallic Ni3Al (Ni3Ga) alloy using the Ni L3,2 and K edge and Al (Ga) K x-ray absorption near edge structure (XANES) measurements. We find that the intensity of near-edge features at the Ni L3 edge in the Ni3Al (Ni3Ga) alloy decreased with respect to that of pure Ni, which implies a reduction of the number of unoccupied Ni 3d states and an enhancement of the Ni 3d state filling in the Ni3Al (Ni3Ga) alloy. Two clear features are also observed in the Ni3Al (Ni3Ga) XANES spectrum at the Al (Ga) K edge, which can be assigned to unoccupied Al 3p-(Ga 4p-) derived states in Ni3Al (Ni3Ga). The threshold at the Al K-edge XANES for Ni3Al shifts towards the higher photon energy relative to that of pure Al, suggesting that Al loses some p-orbital charge upon forming Ni3Al. On the other hand, the Ni K edge shifts towards the lower photon energy in Ni3Al (Ni3Ga) relative to that of pure Ni, suggesting a gain of charge at the Ni site. Thus both Al and Ni K-edge XANES results imply a transfer of charge from Al 3p orbital to Ni sites. Our theoretical calculations using the spin-polarized first-principles pseudofunction method agree with these results.

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The chemical state of particles of 5wt% Fe in α‐Fe2O3 and the subsequently reduced iron particles supported on different particle size (50–200 mesh) of silica (SiO2), alumina (Al2O3), magnesium oxide (MgO) and carbon (C) was examined by Mössbauer spectroscopy at various stages of calcination and reduction. The particle size of the α‐Fe2O3 supported on different mesh sizes (50, 100, 140, 200 mesh) of SiO2 has been determined. The strength of metal‐support interaction with respect to the kind of support was found to be MgO>SiO2>Al2O3>C.

Key Word Indcx-e-Mossbaucr effect; iron catalysts.The effect of the addition of a second metals such as 211 and Ni on the calcinaton and reduction of alumina, magnesia and sillcasupported iron catalysis with total iron loading of 5wt5'6 is investigated by Mossbauer spectroscopy. It is lown that the reducibility of supported a-Fe.O. is gradually increased by adding the second metal. The values of the magnetic hyperfine field obtained frorn Mossbauer spectra for the Zu or Ni-added a-Fe,O. or Fe catalysts decreased with increasing second metal loading.