Rhombohedral shape of hematite nanocrystals synthesized via thermolysis of an additive-free ferric chloride solution

The morphology and structure of hematite nanoparticles synthesized from the widespread technique developed by Matijevic 30 years ago is revisited. The thermolysis of acidic ferric chloride is shown to lead to monodispersed hematite nanocrystallites of rhombohedral shape with facets belonging to the 11041 family, as derived from a joint atomic force microscopy (AFM) and transmission electron microscopy (TEM) investigation. All TEM and AFM data are shown to be accurately accounted for by a unique rhombohedral model particle.