Determination of exchange integrals and effect of cationic site occupancy (8b/24d) on the structural and magnetic properties of nanocrystalline Mn-doped Gd2O3

Mn doped Gd2(1‐x)Mn2xO3 (x = 0.03, 0.05) nanoparticles were prepared by simple co-precipitation method. The distribution of the cations in the six coordinated 8b and 24d sites were determined from Rietveld analysis. In addition, the cation-anion-cation bonds length which are responsible for the super-exchange interaction was extracted to describe the magnetic interaction in the samples. Transmission electron microscopy (TEM) and Raman spectroscopy were employed to investigate the microstructure and presence of any impurity (if any) phase of the samples. X-ray photoelectron spectroscopy (XPS) reveals the decrease in the number of Gd-O bonding and a corresponding increase in Mn-O bonding due to the successful replacement of Gd ions by Mn ions as the concentration increases. The first (nearest neighbor) and second exchange integral (next to nearest neighbor) were determined from molecular field model and the values confirm the occurrence of the antiferromagnetic interaction in the samples. The anomalies in the 1χ vs. T data and non-linearity in M-H curve at 5 K were successfully interpreted by the cationic distribution in different local symmetry sites.