Temperature Dependence of Magnetization, Anisotropy, and Hyperfine Fields of NiFe2–xYbxO4 ( $x = 0$ , 0.05, 0.075)
Temperature dependence of magnetization, anisotropy, and hyperfine interaction parameters of NiFe2-xYbxO4 (x = 0 , 0.05, and 0.075) was investigated, and the results are presented. All the compounds were prepared by solid-state reaction formed in cubic inverse spinel phase with the space group Fd3̅m . Increments in the lattice constant were observed upon partial substitution of Fe3+ by Yb3+. Decreased magnetic moment and increased magnetic anisotropy with Yb3+ substitution were observed through magnetization measurements, carried out at 5, 100, 200 and 300 K. Analyses of Mössbauer spectra recorded at 5 K and 300 K, revealed decreased hyperfine fields and magnetic moments at the B-site (and hence net moment) with increasing Yb3+ content. In addition all the compounds exhibited Neel-type, collinear ferrimagnetic structure.
Mössbauer study of nanodimensional nickel ferrite – mechanochemical synthesis and catalytic properties
Iron–nickel spinel oxide NiFe2O4 nanoparticles have been prepared by the combination of chemical precipitation and subsequent mechanical milling. For comparison, their analogue obtained by thermal synthesis is also studied. Phase composition and structural properties of iron–nickel oxides are investigated by X-ray diffraction and Mössbauer spectroscopy. Their catalytic behavior in methanol decomposition to CO and methane is tested. An influence of the preparation method on the reduction and catalytic properties of iron–nickel samples is established.
Hyperfine interaction and cation distribution of the system Ni1+xSnxFe2−2xO4
Abstract Mossbauer investigations were made on the nickel-tin ferrite system with compositional formula Ni1+xSnxFe2-2xO4. The parameter x was varied and single phase compositions could be obtained only for x ⩽ 0.35. Mossbauer studies were carried out at 300 K and 78 K. The spectra for all the samples showed two well defined Zeeman patterns corresponding to A and B sites. The effect of variation of tin concentration on the various hyperfine interactions has been discussed. From the observed experimental results it is concluded that in the cationic distribution of this series all Sn4+ ions occupy octahedral sites.