A New Systematic Approach to the Morphology and Magnetic Properties of Spherical, Cubic, and Rod-like Magnetite Nanoparticles

Abstract

In this study, a new and systematic approach was taken to study the effect of morphology on the magnetic properties of magnetite nanoparticles. A simple hydrothermal method was used to synthesize spherical, cubic, and rod-shaped nanoparticles. For this purpose, homogeneous solutions of heptahydrate ferro sulfate, deionized water, polyethylene glycol, ammonia, hydrogen peroxide, and alcohol were first made in different proportions. The resulting solutions were heated in an autoclave at 160°C for 5 h to allow the nucleation and growth of the magnetite nanoparticles. The resulting precipitates were then filtered, washed, and dried at 80°C. XRD was utilized to study the phase formation of the synthesized samples and their crystallite size. The morphology of the samples and the particle size were studied using SEM. VSM was used to investigate the magnetic properties. The results showed that spherical, cubic, and rod-shaped magnetite nanoparticles were successfully synthesized without any XRD detectable impurities with the present scan conditions. The crystallite size of the spherical, cubic, and rod-like powders was calculated to be about 17, 22, and 8 nm, respectively, while the average particle size was about 25, 63, and 12 nm, respectively, indicating the polycrystalline nature of the particles, i.e., the particles consisted of many crystallites. All the samples, regardless of the morphology, showed superparmagnetic properties. Magnetite nanoparticles with cubic morphology showed a higher Ms value than the others, while the rod-like nanoparticles exhibited the lowest Ms value. The magnetic saturation values were 60.74, 66.36, and 35.11 emu g−1 for the spherical, cubic, and rod-like particles, respectively.