Magnetic studies of thermally treated Re–Fe (Re = Nd, Gd, and Tb) mixed oxides

Abstract.

Magnetic susceptibility, X-ray diffraction and ⁵⁷Fe Mössbauer measurements have been made on Re–Fe (Re = Nd, Gd, and Tb) mixed Oxides. The mixed oxides of Re–Fe were prepared in different atomic ratios and annealed at various temperatures. The temperature dependence of magnetic susceptibility shows a broad transition around liquid-nitrogen temperature for Nd–Fe mixed oxides. It is attributed to change in the direction of antiferromagnetic moment for the NdFeO₃ as the temperature is lowered. The iron-rich samples have additional transition around 260 K indicative of the αFe₂O₃ phase. Samples annealed at 550 °C show relatively large magnetic susceptibilities characteristic of a fine particle size. In Nd–Fe (1:1) mixed oxides Mössbauer spectra show one six-line pattern, suggesting one crystallographic site of iron ions. T_N observed from the Mössbauer and susceptibility measurements for Nd–Fe (1:1) composition closely agree each other.