LAUSR

Abstract The structural and magnetic properties of Mn doped Nickel Chromite (Ni1-xMnxCr2O4, x = 0, 0.2, 0.3, 0.4, 0.6, 0.8) nanoparticles (NPs) were studied in detail. The X-ray diffraction analysis affirms normal spinel structure for all the samples and average crystallite size was found in the range 31–58 nm. The spinel structure of these nanoparticles was also confirmed by Fourier transform infrared spectroscopy which revealed the formation of tetrahedral and octahedral vibrational bands in the range 607 -628 cm−1 and 486 - 491 cm−1, respectively. Transmission electron microscopy images depicts less agglomerated and non-spherical shaped NPs. The temperature dependent zero field cooled and field cooled magnetic measurements revealed a paramagnetic to ferrimagnetic transition Tc at 87 K for NiCr2O4 NPs, which is shifted to low temperatures by Mn doping. This effect was attributed to cationic distributions between adjacent sites produced by Mn doping. M − H loops of Ni1-xMnxCr2O4 NPs revealed enhanced saturation magnetization with increase in Mn doping which is attributed to a large magnetic moment of Mn ions. Ni1-xMnxCr2O4 (x = 0.6 and 0.8) NPs show steps in their M − H loops because of exchange interactions between two sites of these NPs.