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20152
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Subject: Physics × Author: Sharma, Geeta × Start date: 2000 ×
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    ThesisItemOpen Access
    Modelling for the effect of size and shape with the freedom of pressure and temperature for nanomaterials
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2015-07) Sharma, Geeta; Munish Kumar
    We have developed a simple theoretical model to understand the effect of size, shape, pressure and temperature on nanomaterials. To demonstrate the suitability of the model, we have selected ε-Fe, Ni, Se, and Zr. We have studied the effect of pressure on ε-Fe with different size at different temperature. A small shift in isotherm is found, which demonstrates that more pressure is required at higher temperature for the same compression. In low pressure range (P<5Gpa) the effect of size is very small, but it increases as pressure increases. It is also observed that V/V0 depends linearly on temperature. There is a good agreement between the model predictions and experimental data. To confirm the model predictions, we have repeated our computational work for other nanomaterials. A similar trend of variation confirmed the model predictions. We have extended our model for different shapes of nanomaterials viz. spherical nanosolid, nanowire and nanofilm. We have computed the compression behavior of different shape of Ni with different size and temperature. It is found that the compression curve is shifted upwards as compared with spherical to nanowire and nanofilm. It is also observed that the effect of temperature is not very high. Moreover, it may be computed well. We have repeated our computational work for Cu, Fe and SnO2 and comparison with the available experimental data confirmed the validity of the proposed model. We have computed the size and temperature dependence of lattice parameter of Se, Pb and Ag, which agree well with the available experimental data. We have developed some simple theoretical formulations to study vibrational and thermodynamical properties of β-Fe, Sn, In and Ag in different shapes viz. spherical, nanowire and nanofilm. Size, shape and temperature effect on thermal expansion coefficient and Young modulus have studied quite well alongwith pressure dependence of SOECs of diamond composite and γ-Si3N4 nanomaterials. We have also made an effort to study the hardening and softening of nanomaterials due to reduction of the size of Ge-I, γ-Fe2O3, AlN and γ-Al2O3. It is concluded that the computed results compare well with the available experimental data. This demonstrates the validity of the model proposed.
  • Thumbnail Image
    ThesisItemOpen Access
    Modelling for the effect of size and shape with the freedom of pressure and temperature for nanomaterials
    (G.B. Pant University of Agriculture and Technology, Pantnagar-263145 (Uttarakhand), 2015-06) Sharma, Geeta; Munish Kumar
    We have developed a simple theoretical model to understand the effect of size, shape, pressure and temperature on nanomaterials. To demonstrate the suitability of the model, we have selected ε-Fe, Ni, Se, and Zr. We have studied the effect of pressure on ε-Fe with different size at different temperature. A small shift in isotherm is found, which demonstrates that more pressure is required at higher temperature for the same compression. In low pressure range (P<5Gpa) the effect of size is very small, but it increases as pressure increases. It is also observed that V/V0 depends linearly on temperature. There is a good agreement between the model predictions and experimental data. To confirm the model predictions, we have repeated our computational work for other nanomaterials. A similar trend of variation confirmed the model predictions. We have extended our model for different shapes of nanomaterials viz. spherical nanosolid, nanowire and nanofilm. We have computed the compression behavior of different shape of Ni with different size and temperature. It is found that the compression curve is shifted upwards as compared with spherical to nanowire and nanofilm. It is also observed that the effect of temperature is not very high. Moreover, it may be computed well. We have repeated our computational work for Cu, Fe and SnO2 and comparison with the available experimental data confirmed the validity of the proposed model. We have computed the size and temperature dependence of lattice parameter of Se, Pb and Ag, which agree well with the available experimental data. We have developed some simple theoretical formulations to study vibrational and thermodynamical properties of β-Fe, Sn, In and Ag in different shapes viz. spherical, nanowire and nanofilm. Size, shape and temperature effect on thermal expansion coefficient and Young modulus have studied quite well alongwith pressure dependence of SOECs of diamond composite and γ-Si3N4 nanomaterials. We have also made an effort to study the hardening and softening of nanomaterials due to reduction of the size of Ge-I, γ-Fe2O3, AlN and γ-Al2O3. It is concluded that the computed results compare well with the available experimental data. This demonstrates the validity of the model proposed.