Ethanol sensors based on nano-sized α-Fe2O3 with SnO2, ZrO2, TiO2 solid solutions

Nano-sized α-Fe2O3 based solid solutions with different compositions of SnO2, ZrO2 and TiO2, were prepared using high-energy ball milling technique. Their structural properties and ethanol gas sensing properties were characterized using XRD and gas sensing measurements. The experimental results show that the mechanical alloying processes for these powders are the same. The screen-printed thick film gas sensors made from these mechanically alloyed materials demonstrated very high relative resistance. A non-equilibrium structural model was proposed to explain sensing mechanism. The comparison of gas sensing properties was performed for different α-Fe2O3 based solid solutions with optimized compositions of SnO2, ZrO2 and TiO2. Among these three sensors, xTiO2–(1−x)α-Fe2O3 type of gas sensor has much lower relative resistance value for ethanol. This can be elucidated by the different valence states exhibited by titanium ions.