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20171
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Subject: Physics × End date: 2017 × Start date: 2017 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Study for the thermodynamic properties of nanomaterials under varying conditions of size, shape, pressure and temperature
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2017-07) Bhatt, Sandhya; Munish Kumar
    Present thesis is an attempt to develop a unified theoretical model based on thermodynamic theory of solids to study the thermodynamic properties of nanomaterials under varying conditions of state parameters like pressure and temperature as well as on size and shape. We extended the bond energy model to study the effects of size and shape on melting and superheating for free-standing and embedded nanomaterials. Melting temperature of free standing nanomaterials decreases with the reduction of particle size whereas a reverse trend was found for embedded nanomaterials. A single model was found sufficient to explain both the phenomena. Then, the model was used to explain the specific heat and thermal conductivity of different nanomaterials for spherical as well as polyhedral shapes. Debye temperature and Raman frequency have been predicted successfully for different nanomaterials with spherical, wire and film shapes. Debye temperature, Raman frequency and thermal conductivity decrease with decreasing size whereas specific heat increases. Different models proposed for compression of solids have been modified. The effects of size, shape and temperature have been studied for density of nanoscale materials. Density decreases with the effect of size and shape. However, these effects were found obvious in low size range. A Model has also been developed to study the thermodynamic and elastic properties of nanominerals with the incorporation of size and shape which is also applicable for their bulk counterparts. The results obtained were found in fair agreement with the available experimental and simulation data thereby supporting the validity and applicability of formulations developed. To explain different cases using single model is the dream of researchers and in this thesis we made an attempt to make this dream true. The model predictions may be useful for future studies on nanomaterials.