Preparation and characterization of superparamagnetic α-Fe2O3/Fe3O4@SiO2nanocomposites via a citric-TEOS-ethanol solution combustion process

Abstract

Superparamagnetic α-Fe2O3/Fe3O4@SiO2 nanocomposites were prepared by the citric-TEOSethanol solution combustion method. Four key influencing factors, i.e. the calcination temperature, the volume of anhydrous ethanol, the volume of tetraethyl orthosilicate (TEOS), and the molar ratio of iron nitrate and citric acid (IN:CA) were investigated. The calcination temperature and the volume of anhydrous ethanol mainly affected the phase composition of α-Fe2O3/Fe3O4@SiO2 nanocomposite, and the volume of TEOS and the ratio of IN:CA had a great influence on the crystallinity of α-Fe2O3/Fe3O4@SiO2 nanocomposites. The tendency for the properties of superparamagnetic α-Fe2O3/Fe3O4@SiO2 nanocomposites changing with the conditions was explored and the mechanism was analyzed.