Nano-sized Fe~2O~3 containing 0～14% (mass fraction) Cr~2O~3 was prepared by coprecipitation method using Fe^3^+ (Cr^3^+)/Fe^2^+ mixed ions (with the ions ratio= 2 : 1). XRD Rietveld analysis showed that such Fe~2O~3 was a mixture of crystalline γ-Fe~2O~3 and amorphous Fe~2O~3. The abundance of amorphous Fe~2O~3 ranged from 21.72% to 48. 60%. When the amount of doping Cr~2O~3 was less than 2.4%, the Mossbauer spectra of either the crystalline or amorphous Fe~2O~3 samples were all sextets. If Cr~2O~3 was more than 2.4%, there appearred a superpara-magnetic doublet whose intensity increases linearly with the concentration of Cr~2O~3 . During coprecipitating, there existed two hydrous complexes, one was Fe^3^+ hydrous complexes mixed with a small amount of Cr^3^+, another was Cr^3^+ hydrous complexes mixed with Fe^3^+. These hydrous complexes formed nano-sized magnetic and non-magnetic Fe~2O~3 respectively. The later hydrous complexes mixed with the former, hinderd crystal forming and growth.

Key words: CHROMIUM OXIDE, IRON OXIDE, NANOPHASE MATERIALS, DOPE, MOSSBAUER SPECTROMETRY