Synthesis and Characterization of Tin Oxide as Humidity Sensor

The bulk SnO2 was synthesized by oxidizing the fine powder (50 mesh) of metallic tin (purity 99.99, Aldrich) powder at 750°C for 9 hrs hours in programmable temperature controlled furnace. The gross structure and phase purity of the powder sample ground from sintered pellets were examined by powder X-ray diffraction technique. The phase identification /gross structural characteristics of synthesized SnO2 materials explored through powder X-ray diffracto meter reveals that the sample crystallize in tetragonal structure with lattice parameters a = b = 4.7346Å, c = 3.1787Å. The surface morphology investigated through scanning electron microscope and atomic force microscopy (SEM & AFM) results that pure SnO2 possesses uniform grains and is almost homogeneously distributed, which indicates the high packing density of the materials and nano spheres like structures on the surface of SnO2sample. Average sensitivity of the sensor was found to be 27 MΩ/%RH.