Room temperature ferromagnetic MnCr2O4 spinel chromite nanoparticles

MnCr2O4 spinel is a non-collinear ferrimagnet with transition temperature around 43 K. By means of reducing the particle size to nanoscale regime, the magnetic behavior changes to long-range ferromagnetic order and the transition temperature shifts to above 400 K. MnCr2O4 nanoparticles were synthesized successfully using supercritical conditions of liquid. Changing the reaction conditions, in particular, increasing the reaction time leads to reducing the particles size as well as increasing the magnetic properties of the formed MnCr2O4 nanoparticles. Crystal structures of the synthesized bulk and their nano-scaled candidates were investigated using XRD revealing the same spinel cubic symmetry Fd-3m. Morphology of all samples has been identified using SEM yielding average size of 535±75 nm for bulk sample and 223±50, 195±40, 172±30, 148±27 nm for nanoparticles prepared at reaction time of 2, 4, 6, and 8 hours respectively. The results yield room temperature ferromagnetic behavior at 300 K with magnetization of 6.5, 8.4, 10.8, 17 emu/g, for 223±50, 195±40, 172±30, 148±27 nm respectively. The obtained results confirm the role of reducing the particles size in enhancing the magnetic properties and open new route to probe the ferroelectricity as well as multiferroicity of this system.