Manmeet Pal Singh

Applications of Nanostructured Materials as Gas Sensors

Gas detection instruments are increasingly needed for industrial health and safety, environmental monitoring, and process control. To meet this demand, considerable research into new sensors is underway, including efforts to enhance the performance of traditional devices, such as resistive metal oxide sensors, through nanoengineering. The resistance of semiconductors is affected by the gaseous ambient. The semiconducting metal oxides based gas sensors exploit this phenomenon. Physical chemistry of solid metal surfaces plays a dominant role in controlling the gas sensing characteristics. Metal oxide sensors have been utilized for several decades for low-cost detection of combustible and toxic gases. Recent advances in nanomaterials provide the opportunity to dramatically increase the response of these materials, as their performance is directly related to exposed surface volume. Proper control of grain size remains a key challenge for high sensor performance. Nanoparticles of SnO2 have been synthesized through chemical route at 5, 25 and 50°C. The synthesized particles were sintered at 400, 600 and 800°C and their structural and morphological analysis was carried out using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The reaction temperature is found to be playing a critical role in controlling nanostructure sizes as well as agglomeration. It has been observed that particle synthesized at 5 and 50°C are smaller and less agglomerated as compared to the particles prepared at 25°C. The studies revealed that particle size and agglomeration increases with increase in sintering temperature. Thick films gas sensors were fabricated using synthesized tin dioxide powder and sensing response of all the sensors to ethanol vapors was investigated at different temperatures and concentrations. The investigations revealed that sensing response of SnO2 nanoparticles is size dependent and smaller particles display higher sensitivity. Table of Contents

Effect of Sn doping on morphology and ethanol sensing response of ZnO nanorods

In this work we are reporting the effect of doping of tin on the morphology and sensing response ZnO nanorods. We adopted chemical route to synthesize nanorods of ZnO and then 2% of Sn by weight was added at the time of reaction. To understand the structure we subjected the synthesized materials to XRD and FESEM. The addition of dopant has altered the morphology of ZnO, moreover it has also enhanced the sensing response for ethanol appreciably.

P1.4.11 Fabrication of LPG Sensors Based upon Chemically Tailored Sizes of Chromium Oxide Nanoparticles

In this work, an attempt has been made to alter the particle size of chromium oxide and then to investigate sensing behaviour of these Cr2O3 samples towards LPG. We have followed chemical route for synthesizing nanoparticles of chromium oxide. To tailor nanoparticles of chromium oxide, synthesis was carried out at various reaction temperatures namely, 5, 27 and 65 o C. In order to understand the structure and morphology of synthesized materials; they were subjected to X-ray diffraction and field emission scanning electron microscope. The obtained results have endorsed our prejudice and we found that reaction temperature has played a pivotal role in tailoring particle sizes. Interestingly, we observed that Cr2O3 nanoparticles synthesized at 27°C were smaller as compared to those synthesized at 5 and 65°C. Thick film gas sensors of thus-prepared Cr2O3 powders were obtained by depositing them on alumina substrates. These fabricated sensors were studied for their optimum operating temperatures for LPG and we found that all the sensors exhibited best response at 250°C. The investigation revealed that sensing response of Cr2O3 nanoparticles synthesized at 27°C was exceptionally higher than that of Cr2O3 nanoparticles synthesized at 5 and 65°C.

Gas sensing properties of zinc oxide thin films prepared by spray pyrolysis

Metal oxide semiconductors are widely employed as potential materials for the development of sensing devices for poisonous and inflammable gases. The change in resistivity of active material is exploited as a sensing parameter. A large volume of research work has been carried out in the last few decades on sensors and potential sensor materials. The advent of nanostructured materials has given a new impetus to the sensor research. Preparation and sensing response of zinc oxide thin films towards alcohol has been reported in this paper. Zinc oxide thin film has been prepared by using spray pyrolysis, using zinc acetate and methanol as the starting materials. The thin film was characterized for morphology and structure by using x-ray diffractometer (XRD) and field emission scanning electron microscope (FESEM) techniques. The results indicated that the ZnO particles are crystallized in the wurtzite hexagonal phase, which were well distributed in the films. Prepared zinc oxide thin film was exposed to different alcohols to check its gas sensing behaviour at different temperatures.Metal oxide semiconductors are widely employed as potential materials for the development of sensing devices for poisonous and inflammable gases. The change in resistivity of active material is exploited as a sensing parameter. A large volume of research work has been carried out in the last few decades on sensors and potential sensor materials. The advent of nanostructured materials has given a new impetus to the sensor research. Preparation and sensing response of zinc oxide thin films towards alcohol has been reported in this paper. Zinc oxide thin film has been prepared by using spray pyrolysis, using zinc acetate and methanol as the starting materials. The thin film was characterized for morphology and structure by using x-ray diffractometer (XRD) and field emission scanning electron microscope (FESEM) techniques. The results indicated that the ZnO particles are crystallized in the wurtzite hexagonal phase, which were well distributed in the films. Prepared zinc oxide thin film was exposed to differe...

P1.4.10 Aluminum doping impact on morphology and sensing response of zinc oxide nanostructures

In this piece of work, we have synthesized pure and aluminum doped zinc oxide and then studied their sensing response towards ethanol. We adopted a chemical route to synthesize pure and aluminum doped ZnO, in this work we added different concentrations of aluminum by weight (1% to 4% by percentage weight). The XRD studies revealed that synthesized materials are having wurtzite hexagonal crystalline structures. With the addition of dopant the crystallinity of the structures has decreased. FESEM images have clearly shown the modification of morphology of material with the addition of the dopant. With the addition of dopant sensing responses also have changed significantly.