Novel route for fabrication of nanostructured α-Fe 2 O 3 gas sensor

Iron oxide (Fe2O3) nanoparticles were grown on glass substrate by cost effective, low temperature sol- gel spin coating technique. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy. The hexagonal α-Fe2O3 nanoparticles formation takes place with the predominant orientation along (104) plane. These nanocrystalline α-Fe2O3 samples were used to explore gas response properties for NO2, NH3, H2S and C2H5OH. It is observed that α-Fe2O3 showed higher response (17%) for NO2, gas at 200°C. The high NO2 gas sensitivity and low operating temperature of α-Fe2O3 nanoparticles can be attributed to the surface morphology. The reproducibility and stability study of the Fe2O3 sensor confirmed its candidature for detection of NO2 gas at low concentration (10–100ppm) and at low operating temperature. Results of impedance spectroscopy revealed that the change in resistance of the film after exposure to NO2 is mainly contributed by intragrain region. On interaction with NO2 the electrons trapped by adsorbed oxygen in the grain boundary are released which decreases the majority carriers and thus increasing the resistance of the Fe2O3 film.