Alcohol sensor based on a non-equilibrium nanostructured xZrO₂-(1-x)α-Fe₂O₃ solid solution system

Non-equilibrium nanostructured solid solution xZrO₂-(1-x)α-Fe₂O₃ powders have been prepared using the high-energy ball milling technique, and their particle size, structural properties and alcohol gas properties have been systematically characterized using X-ray diffraction (XRD) and gas sensing measurements. Experimental results show that particle size of the powder is drastically milled down to less than 10 nm after 20 h of high-energy ball milling. Our modified structural model, □_1/3+ZrO₂+yO₂ →Zr_1/3⁴⁺+2(1-y)O_s^2-+4yO_s^-; with □_1/3 denoting the 1/3 available octahedral sites of the corundum structure; for these non-equilibrium nanostructured solid solution xZrO₂-(1-x)α-Fe₂O₃ materials can explain both the lattice expansion of these high energy milled sample as well as the charge neutrality in terms of additional oxygen dangling bonds at the particle surfaces. The screen-printed thick film gas sensors made from such mechanically alloyed materials demonstrate a very high gas sensitivity value of 1097 at 1000 ppm of alcohol gas in air. It is believed that the high gas sensitivity value is related to the enormous oxygen-dangling bonds at the particle surfaces.