Preparation and characterization of hollow magnetite spheres via a template-free route

Abstract

Hollow magnetite (Fe3O4) spheres have been synthesized successfully via a template-free hydrothermal reaction using Fe-naphthenate and LiOH as the starting materials. The average diameter of hollow magnetite spheres prepared at 120°C was about 10μm, and the specific surface area of the product was 68.3 m2/g. The size and morphology of the products depended on the reaction temperature, concentration of LiOH solution and the volume ratio of the oil (Fe-naphthenate) and water phase (LiOH solution). The hollow magnetite spheres exhibit ferromagnetic behavior with saturation magnetization (Ms), remanent magnetization (Mr), and coercivity (Hc) values of ca. 22emu/g, 5emu/g, and 530 Oe, respectively, according to the magnetic hysteresis curve measured at 5K. The possible formation mechanism of hollow magnetite spheres is also discussed. ©2010 The Ceramic Society of Japan. All rights reserved.