Fabrication, characterization, and formation mechanism of hollow spindle-like hematite via a solvothermal process

As a novel hollow nanostructure, hollow spindle-like hematite with uniform size and morphology was solvothermally synthesized. These hollow polycrystalline particles with the length of 220-300 nm, the width of 70-100 nm, and the wall thickness of ca. 18 nm were characterized by TEM, FE-SEM, XRD, FT-IR, TGA, M?ssbauer spectrum, and XPS methods. It was found that these hollow-structured particles were transformed from their original solid spindle particles. During the hollow structure formation process, the interiors of solid particles were preferentially dissolved while the retained exteriors were protected by coordinated sulfate ions. The formation mechanism was proposed as a coordination-assisted dissolution process occurred in a reverse microemulsion system.