Thermal and electrical behaviour of nanomaterials under the influence of size, shape and pressure
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Date
2019-08
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
In the present work, the effect of size, shape and pressure have been studied on thermal and electrical properties of nanomaterials. Collective effect of size and pressure has been analyzed on thermal properties like Grüneisen parameter, melting temperature and Debye temperature for metallic nanoparticles. It was observed that Grüneisen parameter decreases with the decrement in the size of nanoparticle. The obtained results from the combined study of size and pressure on Grüneisen parameter revealed that Grüneisen parameter decreases linearly with increment of pressure. Most of the metal nanoparticles show approximately 5-10 % decrement. While the Debye temperature and melting temperature show an opposite behavior (i.e. increment) under the effect of pressure for nanoparticles. Present thesis work not only focused on metal nanoparticles but also provides the size and shape dependent behaviour of electrical resistivity for metal nanowires. On moving towards the nano range, the scattering effects play important role therefore in this study the effect of electron scattering (surface scattering and grain-boundary scattering) is incorporated with size and different cross-sectional shapes of nanowires. It has been obtained that electrical resistivity have higher value than the bulk value due to size reduction and scattering effects. The results also revealed that the shape effect is also an important factor at nano range. The electrical resistivity is higher for nanowires having large shape factor and is lowest for circular nanowires. An enhancement in the value of electrical resistivity has observed with the increment in reflection coefficient. The present work also includes the dielectric study of semiconductor nanomaterials. The size and dimension effect on electrical susceptibility and dielectric constant has been observed. It was found that electrical susceptibility and dielectric constant both decreases with decreasing size of nanomaterials. It was also observed that the electrical susceptibility and dielectric constant depends on the dimension of nanomaterials, the largest decrement was found in nanoparticles and the least for nanofilms. Shape effect has also been incorporated for semiconductor nanowires and the results showed that non-cylindrical nanowires have less value of dielectric constant in comparison to cylindrical nanowires. The obtained results have been compared with the available simulated and experimental data. Consistency in results of proposed model and available experimental data supports the validity of present work.
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