GRANULAR FILMS OF IRON-OXIDE PREPARED BY AEROSOL DEPOSITION FOR THE DETECTION OF ORGANIC VAPORS

Gas-sensitive layers of iron oxide microparticles have been obtained b y nebulization of iron oxalate solution, size-selective deposition of the dried aerosol particles and final heating at 350-degrees-C to tran sform the oxalate to iron oxide. Clustered layers of spherical particl es with a size of about 800 nm resulted. For comparison sputtered iron films were oxidized at the same temperature to yield oxide films of c ompact morphology. With secondary-neutral and secondary-ion mass spect rometry film thicknesses, elemental compositions and chemical states w ere measured. All prepared iron oxides were determined to be primarily Fe2O3. The granular as well as the compact iron oxide films were inve stigated concerning their change in electrical conductivity upon expos ure with organic gases contained in air. The sensitivities at 350-degr ees-C for propane and methane, but not for benzene, were found to be h igher for the granular films. The response times were not much differe nt between the particulate and the compact iron oxide layers.