Influence of Cu addition on the structural, magnetic and magnetocaloric properties of the PrCo3 intermetallic compound

Abstract

The structural, magnetic and magnetocaloric properties of PrCo3−xCux intermetallic compounds were investigated in the composition range 0 ≤ x ≤ 0.6. X-ray diffraction investigations showed that all of the samples crystallize in the PuNi3-type crystal structure after annealing at 850 ∘C for 16 days. An anisotropic expansion of the unit cell along the c-axis occurs when the Cu concentration increases. Electronic structure calculations were performed, showing a good agreement with the experiments. The Curie temperatures decrease from 333 K for x = 0 to 170 K for x = 0.6, due to a weakening of the exchange interactions with the reduction of the effective number of magnetic nearest neighbors. All of the samples were found to be ferromagnetically ordered, the saturation magnetization at 4.2 K being inversely proportional to the Cu concentration value. The Co atomic moments decrease as the Cu content value increases due to the progressive filling of the Co 3d bands. Also, magnetic investigations at low temperatures suggest an enhancement of the magnetocrystalline anisotropy when Cu is added. A moderate magnetocaloric effect was found for all of the investigated samples. The maximum magnetic entropy change values, measured in an applied field ranging from 0 to 4 T, decrease from 1.39 J/kgK for x = 0 to 0.91 J/kgK for x = 0.6, while the RCP(ΔS)∕ΔB values are rather independent of Cu concentration.