STRUCTURE, MORPHOLOGY AND MAGNETIC PROPERTIES IN Fe/Fe3O4 NANOCOMPOSITES

Abstract

The influence of annealing temperature on the structure, morphology and magnetic properties of Fe/Fe₃O₄ nanocomposite powder was investigated. The samples were fabricated by combining high-energy ball milling and annealing at temperatures of 623, 723 and 823 K. The structure and morphology of the samples were characterized by X-ray diffraction, scanning electron microscopy. These measurements indicated the evolution of the crystalline phases of the samples as the temperature increases. At the same time, the morphology of the samples changed abnormally at different annealing temperatures: granular (623 K), leaf (723 K) and rod (823 K). The room-temperature magnetization measurements pointed out a decrease of saturation magnetization as annealing temperature increases, while coercivity increases. Besides, the presence of a Verwey phase transition near 120 K is confirmed the good crystal quality of Fe₃O₄ phase. Our study demonstrates the possibility of tuning the morphology and magnetism in iron/iron oxide nano systems through controlled oxidation at the different temperatures.