Structural and magnetic properties of nanocrystalline PrCo3−xFex

Abstract

We have studied nanocrystalline of PrCo3−xFex prepared by high energy milling technique. The as-milled samples were subsequently annealed in the temperature range from 873 to 1273K for 30min in order to optimize their extrinsic properties. Their structural and magnetic properties were investigated by means of X-ray diffraction (XRD) coupled with Curie temperature determination and magnetization measurements. These compounds crystallize in the PuNi3-type structure (space group: R3¯m) for x≤1. The composition is in a three phase field Pr(Co,Fe)3, Pr2(Co,Fe)17 and Pr(Co,Fe)2, for 1<x≤2, and then is in two phase field Pr2(Co,Fe)17 and Pr(Co,Fe)2 for larger x. The Rietveld refinement showed that the substitution of cobalt by iron leads to an increase of the unit cell volume. The Curie temperature (TC) of the PrCo3−xFex samples increases from 350K for PrCo3 to 580K for PrCo2Fe, the enhancement of TC is ruled by electronic and magnetovolumic effects. From X-ray studies of magnetically aligned samples, the magnetic anisotropy of these compounds changes from the c-axis to the cone anisotropy. The magnetization of the compounds increases as cobalt is replaced by iron and no saturation reached at room temperature for an applied field of 90kOe. The hard magnetic properties are obtained after annealing at 1023K for 30min where the coercivity achieved HC=5kOe.