Intrinsic and extrinsic magnetic properties of nanocrystalline Pr₂(Co,Fe)₇

In this work, we present a study focused on the effect of partial substitution of Co by Fe on structure and magnetic properties of nanocrystalline Pr₂Co₇. These compounds were synthesized by mechanical alloying and to correlate their properties with microstructural evolution, a multi‐scale study by: X‐ray diffraction (XRD), transmission electron microscopy, and magnetization was carried out. The Rietveld analysis of XRD diagrams shows that Pr₂Co_7−xFe_x, annealed at 973 K, mainly adopt a hexagonal Ce₂Ni₇ type structure with P6₃/mmc space group. These pseudo‐ternary compounds exhibit more interesting magnetic properties than the binary Pr₂Co₇ compounds. A systematic study of the intrinsic magnetic properties of these alloys shows that the substitution leads to enhancement of the Curie temperatures (T_C) by 26% for a Fe content equal to 0.5. This increase is due to the electronic as well as the magnetovolume effects. In addition, the study of extrinsic magnetic properties of the Pr₂Co_6.5Fe_0.5 compound has revealed the existence of a large coercive field H_c, and a high remanent magnetization M_r. Our results show that in these alloys, iron in solid solution has a strong effect on hardness and ordering temperature, which is particularly promising for permanent magnet applications.