Nanostructured CuO–α-Fe2O3 solid solution obtained by high-energy ball milling

The mixture of α-Fe2O3 and CuO crystalline powders in equimolar ratio was subjected to high-energy ball milling to investigate the solid solution process in this system. The phase evolution in the system during the milling was studied by means of X-ray diffraction and Mössbauer spectroscopy. It was found that nanostructured solid solution of CuO–α-Fe2O3 with a corundum structure was obtained. Within the solid solution, there existed a gradient distribution of concentration of CuO from the surface to the interior of α-Fe2O3. The dissolution of CuO in the α-Fe2O3 greatly lowered the Néel temperature of α-Fe2O3, which resulted in paramagnetism of the as-milled solid solution whose Mössbauer spectrum showed a doublet absorption line at room temperature.