Para, ferro and antiferromagnetic properties of MnO2 and Ce1−x Mn x O2 nanoparticles

Abstract

Manganese-substituted cerium oxide nanoparticles (Ce1−x Mn x O2) at x = 0.00, 0.03 and 0.05 were prepared using ball milling technique and the milled powder samples were subjected to different characterization techniques such as X-ray diffractometer (XRD), scanning electron microscope with energy dispersive analysis of X-rays and vibrating sample magnetometer to study the structural, morphology and magnetic properties, respectively. From XRD, it was confirmed that the prepared samples were in Cubic structure at all Mn-doping concentrations and no evidence of impurities were found. The crystallite sizes of the powders were in the range of 30–44 nm and it decreased with increase of Mn substitution. The SEM images reflected that the grains are uniform in size and are in spherical shape. From magnetic studies, it was found that the bulk MnO2 was paramagnetic in nature, whereas the CeO2 nanoparticles were soft ferromagnetic at room temperature. The pure CeO2 nanoparticles exhibited a magnetization of 4.79 memu/g, coercivity of 389 Oe, and retentivity of 2.08 memu/g. A drastic change in magnetic behaviour of CeO2 nanoparticles was found by the substitution of Mn into the CeO2 host lattice. The Ce1−x Mn x O2 nanoparticles exhibited soft ferromagnetism at low field and antiferromagnetism at high applied magnetic fields. No magnetic saturation was found in Ce1−x Mn x O2 nanoparticles even when the magnetic field is increased to 15 kOe.