Fabrication and Formation Mechanism of Hollow-Structure Supermagnetic α-Fe2O3/Fe3O4 Heterogeneous Nanospindles

A simple process for the fabrication of hollow-structure supermagnetic alpha-Fe2O3/Fe3O4 heterogeneous nanospindles was introduced with beta-FeOOH as precursors fabricated by the hydrolysis method. The effects of Fe3+ concentration and hydrolysis conditions on the morphology and characteristic of beta-FeOOH were researched in detail. When the reaction conditions were 0.1 M Fe3+ and hydrolysis at 70 degrees C for 2 h, the good morphology beta-FeOOH nanospindles with an average diameter of 56 nm and length of 223 nm were obtained. Under high-temperature calcination and reduction by PVP, beta-FeOOH nanospindles were transformed into supermagnetic alpha-Fe2O3/Fe3O4 heterogeneous nanospindles with hollow-structure. Simultaneously, the effects of reducing agent and calcination conditions on the phase composition and magnetic property of the hollow-structure supermagnetic alpha-Fe2O3/Fe3O4 heterogeneous nanospindles were investigated, and the product calcined at 500 degrees C for 1 h was characterized with the saturation magnetization of 27.6 emu/g, the average length of approximately 301 nm, the average diameter of about 72 nm, and the shell thickness of around 11 nm when the mass ratio of beta-FeOOH to PVP was 1:1. The prepared hollow-structure alpha-Fe2O3/Fe3O4 heterogeneous nanospindles with the controlled magnetic properties were a type of very promising material. [GRAPHICS] .