Impact of particle size on the structural and smagnetic properties of superparamagnetic Li-ferrite nanoparticles

摘要

This report, investigates the influence of particle size on the structure, vibration, and magnetic properties of superparamagnetic LiFe_5O_8 nanoparticles, which is annealed at various temperatures (500, 600, and 700 °C) using a low-cost auto-combustion method. The Li ferrite nanoparticles have been studied using a variety of characterization techniques: powder x-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. The magnetization measurement M(H) at room temperature showed that the annealed ferrite nanoparticles exhibit a superparamagnetic arrangement of single-domain particles due to the structural disturbance in the surface shell of the nanoparticles which is far from equilibrium. We present detailed magnetic measurements such as field cooled and zero field cooled measurements, ac susceptibility, and time decay of magnetization relaxation. Their analysis has been performed using various phenomenological models viz. Neel-Arrhenius, Vogel-Fulcher and power-law model strongly suggests the presence of a spin glass-like behavior in nanoparticles of Li_(0.5)Fe_(2.5)O_4. The results presented in this study highlight the key findings that spin-glass behavior of LiFe_5O_8 is strongly size-dependent. Overall, these samples are excellent prototypes for studying the size effect on magnetic materials and can be used in various technological applications such as magnetic resonance imaging, magnetic hyperthermia, and high-frequency microwave devices.