Synthesis chemical method of maghemite (γ- Fe2O3) nano-particles

In this research maghemite (γ -Fe2O3) nano-particles were produced by a new one-step chemical method at room temperature and characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), The average particle size of the maghemite was estimated to be 48 and 59 nm, by SEM, respectively. However, XRD and SEM estimated the average particle size of the maghemite nano-particles about 12and 17 nm, respectively. the SEM images showed that the γ-Fe2O3 nano-particles were of approximately spherical shape. As a result, pure maghemite nano-particles below 60 nm in size could be produced without using organic solvent and oxidation. Metal oxides nano-particles are significant in modern materials science because of their potential technological importance, which stems from their unique physical properties. Maghemite (γ -Fe2O3) is an important material for many applications. Due to its specific structure, and distinct catalytic, and magnetic properties, maghemite has been used in color imaging, bio-separation, magnetic refrigeration, ferro fluids, gas sensors, information storage, etc. [1,2,3]. Various methods have been reported for the synthesis of maghemite nano-particles, such as co-precipitation [4], sol–gel synthesis [5], micro emulsion [6], flow injection synthesis [7], flame spray pyrolysis [8], decomposition of organic precursors at high temperatures, and the oxidation of magnetite nano-particles [9]. Industrially, maghemite nano-particles are usually prepared in two steps. In the first step, magnetite is synthesized by chemical co-precipitation of ferric and ferrous ions in an alkali solution, and in the second step, magnetite is oxidized by aeration at 200-4000C (reaction 1) [4, 10]. During the heat transfer, the particles are subjected to agglomeration which results in a larger particle size distribution. In this paper, a simple one-step method for the synthesis of γ -Fe2O3 nano-particles is presented. This method is innovative and does not required organic solvents and heat treatment. Pure maghemite with an average particle size below 60 nm can be produced without any hematite and magnetite impurities.