A chemical route has been used to synthesize composite oxides of zinc and tin. An ammonia solution was added to equal amounts of zinc and tin chloride solutions of same molarities to obtain precipitates. Three portions of these precipitates were annealed at 400, 600 and 800°C, respectively. Results of X-ray diffraction and transmission electron microscopy clearly depicted coexistence of phases of nano-sized SnO2, ZnO, Zn2SnO4 and ZnSnO3. The effect of annealing on structure, morphology and sensing has been observed as well. It has been observed that annealing promoted growth of Zn2SnO4 and ZnSnO3 at the expense of zinc. The sensing response of fabricated sensors from these materials to 250ppm LPG and ethanol has been investigated. The sensor fabricated from powder annealed at 400°C responded better to LPG than ethanol.

Sensing response of ‘self-binding’ nanoparticles of tin dioxide powder deposited on alumina substrate has been investigated. The nanocrystalline SnO2 powder has been derived from stannic chloride. It has been prepared through fine crystallization in liquid phase. SnO2 powder has been characterized using SEM, TEM and XRD techniques, which reveal that the average crystallite size is of 12nm. The slurry blobs deposited on alumina substrate of the powder-thus-prepared have been studied for sensing response to ethanol at various temperatures and concentrations. The observations reveal that the material prepared is ‘self-binding’ and is very sensitive even without catalyst.

Tin dioxide nanoparticles and zinc oxide nanorods were synthesized chemically and thick film gas sensors on alumina substrates were fabricated of these materials. Morphology and crystallite size of synthesized powders were investigated by TEM. The fabricated sensors were irradiated with 100 MeV O7+ ions at fluences of 1×1011, 1×1012 and 1×1013 ions/cm2. The X-ray diffraction analysis of the samples before and after ion bombardment was performed for structural characterization. The sensing response to ethanol before and after irradiation was carried out for each fabricated sensor. Investigation revealed that irradiated SnO2 based sensor’s response and response time increased significantly. Results show that ZnO based sensor exhibit strong resistance to damage caused by ion irradiation which might be due to defects annihilation.

Nanoparticles of SnO2 have been synthesized through chemical route at 5, 25 and 50°C. In this work the synthesized particles were calcined at 400, 600 and 800°C and their structural and morphological analysis was carried out using X-ray diffraction and transmission electron microscopy. The reaction temperature has been found to be playing a critical role in controlling nanostructure sizes as well as agglomeration. It has been observed that particles synthesized at 5 and 50°C were smaller and less agglomerated as compared to the particles prepared at 25°C. The study also reveals that particle size and agglomeration increases with increase in calcination temperature. Thick film gas sensors were fabricated using synthesized tin dioxide powder, and sensing response of all the sensors to ethanol vapours was investigated at different temperatures. The investigations reveal that sensing response of SnO2 nanoparticles is size dependent and smaller particles are highly sensitive.

A comparative study of sensing response of zinc oxide nanoparticles and nanorods to ethanol vapours has been reported in this paper. Zinc oxide powder has been synthesized as nanoparticles and nanorods by following a chemical route. The reaction temperature is found to be playing a critical role in the selective synthesis of morphologically distinct nanostructures. Synthesized zinc oxide powder was characterized by using TEM and XRD techniques. Zinc oxide samples were deposited as thick films to act as gas sensors and their comparative response to ethanol vapours was investigated at different temperatures and concentrations. In this work the effect of sintering temperature on the particle size and sensor sensitivity was also studied. The studies revealed that particle size increases with the sintering temperature while sensitivity decreases. The investigations also revealed that sensing response of ZnO nanoparticles is exceptionally higher than that of ZnO nanorods.

The simple and inexpensive technique to synthesis nano crystalline tin oxide powder has been reported in this work. The nano crystalline tin oxide powder has been derived from stannic chloride, prepared through fine crystallization in liquid phase. Tin oxide powder has been characterized using SEM, TEM & XRD techniques which revealed crystal size around 13 nm. The slurry blobs deposited on alumina substrate of the powder thus prepared have been studied for sensing response of ethanol at various temperatures. The observations revealed that the material prepared is self-binding whereas commercial tin oxide powder required binders for sensor applications. Sensing response of nano particles of tin oxide deposited on alumina substrate has been investigated it was found very significant even without catalyst. These properties may have been attained by the prepared material due to the shift in the nano-scale range.