Abstract: Taking pyrite as the iron source， Fe³⁺ leaching solution was obtained through roasting， chemical leaching and impurity removal. Then，α-Fe₂O₃ nanopolyhedra was synthesized by hydrothermal method via Cu²⁺ inducement. The structure and morphology of α-Fe₂O₃ nanopolyhedra were characterized by X-ray diffraction (XRD)， scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) to investigate their nucleation and crystal growth. The results showed that α-Fe₂O₃ nanopolyhedra with a hexagonal structure was about 500nm in grain size. Based on the morphology observation of the as-prepared products synthesized at different hydrothermal times and the analysis result of solution chemistry calculations， it is concluded that the formation of α-Fe₂O₃ nanopolyhedra is followed by the precipitation， dissolution and recrystallization. The presence of Cu²⁺ mainly induces the crystal nucleus of α-Fe₂O₃ so as to form nanopolyhedra structure in the process of growth.

Key words: α-Fe₂O₃, nanopolyhedra, hydrothermal method, crystal growth, solution chemistry