Aging effects in NaFeO2 nanoparticles: Evolution of crystal structure and magnetic properties

Abstract NaFeO2 magnetic nanoparticles which are biocompatible and have a relatively high saturation magnetization are considered as promising heat mediators for magnetic hyperthermia applications. In this work, we study aging effects in NaFeO2 nanoparticles and show that they change their structural and magnetic characteristics over time. As-produced NaFeO2 nanoparticles synthesized by sol–gel technique have been aged in the ambient atmosphere for 10,000 h. Magnetic properties and aging effect were studied by X-ray diffraction and vibrating sample magnetometry at a temperature ranging from 300 to 500 K. Crystal structure of nanoparticles undergoes essential changes, including an increase of lattice parameter and average coherent block size, and decrease of the microdeformation of crystal lattice. These structural changes affect magnetic parameters of the aged sample. It is shown that saturation magnetization becomes higher and Curie temperature tends to increase as the samples undergo the aging processes.