Different Morphology Of Nano ¦Á-fe <sub> 2 </ Sub> O <sub> 3 </ Sub> And Its Hybrid Films Preparation And Gas Sensitivity Study

The preparation of three different shapes a-Fe2O3 nano-particles by means of force hydrolyzation was discussed in this paper. By controlling the experimental conditions (Fe3+ concentration, acidity, reaction time, reaction temperature etc.), the particles with different shapes (ellipsoidal, pseudocubic, sphere) were obtained. The thin films were fabricated by dip-coating technique. The gas-sensing properties of a-Fe2O3 thin films with different shape to alcohols were investigated. The formation mechanism of pseudocubic a-Fe2O3 nanoparticles was discussed.The thin films of two kinds of copper phthalocyanines were prepared by spin-coating technique. The surface morphology of the thin films was characterized by AFM. Obvious nano-domains were observed on the surface of the isopropoxyphthalocyanine thin film, while acicular crystals were found on the surface of the phenoxylphthalocyanine film. The gas-sensing properties of those films were studied. It showed that the phenoxylphthalocyanine thin films exhibited higher gas sensitivity to the alcohols than the other one.The organic/inorganic alternating composite films were further fabricated by spin-coating technique, using isopropoxyphthalocyanine and a-Fe2O3 (with pseudocubic or sphere shape) as the staring materials. The films were characterized by AFM and UV-Vis spectra, respectively. The effect of the phthalocyanine molecules on the gas sensing property of the composite film was discussed by considering the structural changes in the composite films. The results indicated that the composite films exhibited much improved gas sensing performance.The phthalocyanine and its a-Fe2O3 embedded nano-particulate LB filmswere prepared by Langmuir-Blodgett (LB) technique. The films were characterized by AFM, UV-Vis and FT-IR spectra. The results indicated that the embedded LB films were composed of a-Fe2O3 nanoparticles and isopropoxyphthalocyanine molecules. The gas sensitivity of such prepared composite LB films was greatly improved. The film could detect 5ppm of propyl alcohol at room temperature. The composite films could be considered as gas-sensors for alcohols.