Magnetic properties of superparamagnetic β-NaFeO2 nanoparticles

Superparamagnetic beta-NaFeO2 nanoparticles of particle size 37 nm with orthorhombic crystal structure and space group Pn2(1)a have been prepared by sol-gel method. Temperature dependent magnetic study has been performed. Its systematic analysis has been done to calculate the Curie and blocking temperatures along with its magnetic susceptibility. The Langevin fitting of the magnetic data has been carried out. It has been shown that the synthesized nanoparticles exhibit superparamagnetic behavior. The Neel's relaxation time has been calculated to further support its superparamagnetic nature. The synthesized beta-NaFeO2 nanoparticles behave like ferromagnets below 80 K; they are superparamagnetic above 80 K-340 K and thereafter as paramagnetic. The possible mechanism of superparamagnetism has been discussed. It has been concluded that these nanoparticles can find wide applications in the area of biomedical sciences. (C) 2018 Elsevier B.V. All rights reserved.