Synthesis of monodisperse ellipsoids with tunable aspect ratios

Monodisperse ellipsoids were synthesized by continuous coating of silica on hematite spindle cores. Spindle cores with decreasing aspect ratio were obtained by decreasing the molar ratio of Fe3+ and H2PO4−. Using PVP molecules as the surface stabilizer for silica coating, the aspect ratio of the ellipsoids can also be tuned by altering the amount of added TEOS. These monodisperse ellipsoids with well controlled sizes and aspect ratios can be regarded as the potential building blocks for self-assembly.