Ce-doped nano-α-Fe₂O₃ was successfully synthesized via the hydrothermal method. The properties of the prepared particles were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and electrochemical methods. It was found that the Ce element can be doped into the α-Fe₂O₃ lattice resulting in lattice distortion, which can refine the grain and improve the crystal surface’s integrity significantly. In addition, doping of Ce element can shorten the Fe–O bond length in the α-Fe₂O₃ crystal, cause a blue shift of the stretching vibration band, enhance binding energy of Fe–O and the chemical stability of the α-Fe₂O₃ crystal.

La-doped α-Fe₂O₃ nanoparticles were synthesized by a hydrothermal method. The effects of pH value on the morphology, structure, and electrochemical stability of the La-doped α-Fe₂O₃ nanoparticles were investigated by X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectrum, and electrochemical methods. The results show that the La-doped α-Fe₂O₃ nanoparticles exhibit a uniform spherical morphology at pH = 6, and are agglomerated with a poor dispersion at pH = 4 and 8. The iron oxide lattice is distorted by the La-doping, which increases the Fe–O bond strength. The decreased Fe–O bond length and the increased Fe–O bond energy at pH = 6 improve the electrochemical stability of α-Fe₂O₃. The waterborne coating modified with La-doped α-Fe₂O₃ nanoparticles exhibits a steady corrosion resistance.