Mechanical alloying of an immiscible α-Fe₂O₃-SnO₂ ceramic

A solid solution of about 6 mol% SnO2 in alpha-Fe2O3 has been prepared by mechanical alloying of alpha-Fe2O3 and SnO2 powder blends. This result demonstrates that high energy ball milling can be used to prepare metastable oxide solid solutions with an extended range of compositions in the immiscible ceramic oxide system. X-ray diffraction and Mossbauer spectroscopy investigations show that mechanical milling of alpha-Fe2O3 and SnO2 involves alloying on an atomic scale and that true solid solution formation occurs. We suggest that the high defect concentration and the chemical enthalpy of Fe3+-O2--Sn4+ interfaces between nanostructured alpha-Fe2O3 and SnO2 regions may serve as a driving force for the formation of a solid solution in the immiscible ceramic system.