Double-walled SnO2 nano-cocoons with movable magnetic cores

Double-walled SnO2 nano-cocoons with movable alpha-Fe2O3 cores have been prepared by hydrothermal shell-by-shell deposition of polycrystalline SnO2 on ellipsoidal alpha-Fe2O3/SiO2 core/shell nanotemplates followed by removal of SiO2. The present templating approach also leads to two other nano-architectures, namely single-walled and porous double-shelled nano-cocoons. The alpha-Fe2O3 cores can be reduced to magnetic Fe3O4 post-synthesis.