Development of unified model for the size and shape dependent properties of nanomaterials
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Date
2019-11
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
In the present thesis, we made an attempt to develop a unified model based on the Bond energy model to study the thermodynamic properties of nanomaterials under varying conditions of size, shape, pressure, and temperature. We extended the model to compute the size and shape dependence of magnetic properties viz. Curie temperature TC(D), magnetization MS(D) and Neel temperature TN(D), where D denotes the size of nanoparticles. It is found that TC(D) and MS(D) decrease with decrease in size. TN(D) is found to increase or decrease with dropping D, depending on the interaction strength at the film/substrate interface. It is observed that the shape effect is much more prominent for the smaller size and decreases for greater size. The model was extended to other nanomaterials in different sizes and shapes. The results obtained for corresponding bulk material are also included for comparison purposes. Surface to volume atomic ratio is also computed using the present model and used to explain the results. We used Murnaghan EOS to study the compression behavior of nanomaterials and it shows a slight variation at high pressures for bulk materials. Further, a unified model has also been used to study the effect of size, shape, pressure, and temperature on different properties of nanomaterials as well as bulk materials. A fair agreement between theory and experiment demonstrates the suitability of the theory used in the present thesis. Some results are reported in the absence of experimental data that may be useful for future studies. To discuss different phenomena using a single model is the dream of researchers, which is much difficult task. Moreover, the present thesis provides the theory for this purpose and therefore, the work may be useful for researchers.
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