Loading...
Theses
Browse
10 results
Search Results
ThesisItem Open Access Study for the effect of pressure, size and shape of nanomaterials(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2020-12) Mehra, Laxmi; Munish KumarNanomaterials at high pressure are one of the major areas of interest due to its immense potential of applications. Due to a small size nanomaterials shows novel properties. Nanoparticles are used in a variety of application, such as sensors, LEDs, drug delivery, medical diagnostics, catalyst and gene therapy. Their unique range of properties and enormous application led to the development of the nanotechnology. In the present thesis we used the Murnaghan EOS for various nanomaterials. We have computed the pressure dependence of V/V0 for different sizes and shapes viz. Film, dodecahedral, icosahedral, wire, spherical, octahedral and tetrahedral. The materials which we included in the present study are viz. MgO (20nm), MgO (11nm), ZnO2 (3.1nm), WC (25nm), n-ReB2 (40nm), n-Re0.52W0.48B2 (30nm), TiN (18nm), TiN (34nm), TiN (80nm), α-Ga2O3 (14nm), β- Ga2O3 (14nm), Ho2O3 (14nm) because of the experimental data are available on these materials so the comparison is also possible. We studied the nanomaterials for the different sizes and shapes in room temperature. A shift in isotherm is observed with the increase in size. We studied the compression behaviour of nanoparticles for different shapes and observed that there is a shift in isotherm curve and found larger for the film indicated that they are most compressible and smaller for the tetrahedral indicated that they are least compressible. This is due to the different surface to volume ratio of nanoparticles for different shapes. Our results are found to be in good agreement with the experimental data. Hence it proves the validity of the theory of EOS used in the present thesis.ThesisItem Open Access Mineralization of dichlorvos pesticide by copper nanoparticles: optical absorption and energy band gap analysis(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2020-12) Chauhan, Deepak; Goel, PujaNanoparticles are getting great attention globally due to their unique physical and chemical properties, high surface area and nanoscale size etc. In the present work, the suspension of copper nanoparticles was prepared and studied the application of Cu NP’s in the degradation of dichlorvos pesticide. To obtain stable suspension of Cu NP’s, a specific amount of isopropanol solvent and surfactant i.e. oleic acid were chosen. XRD technique was used to estimate particle size and phase analysis of Cu nanopowder. UVVIS and FTIR spectroscopy were used for characterization of prepared Cu nanosuspension. It inferred that the oleic acid efficiently stabilized the nanosuspension but it was not sufficient to prevent the oxidation of Cu NP’s. To study the application of Cu NP’s in pesticide degradation, solution of different concentrations of dichlorvos pesticide were prepared. A specific amount of Cu nanosuspension was added to prepared pesticide solutions and observed with time. The effect of Cu NP’s on dichlorvos pesticide was observed by observing the change in colour of samples with time. UV-VIS and FTIR spectroscopy were used to characterize the reaction products. The UV-VIS plasmon of nanosuspension showed a red shift. The FTIR spectra confirmed the degradation of organic bonds of the dichlorvos. As a result of the interaction between dichlorvos and Cu NP’s, the pesticides have been successfully degraded.ThesisItem Open Access Comparative study of different equations for the effect of shape and size on young’s modulus(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2020-12) Sharma, Kamal; Joshi, Deepika P.In the current work a comparative study of four unique models (Jiang's model, Qi-Wang's model, Qi's model and Lu's model) have been done for investigating shape and size effect on Young's modulus for different classes of solids (i.e. nanometals and semiconductors). After choosing the best model for mechanical properties of semiconductors, the work has been extended to investigate the shape and size effect on electrical properties like band gap, dielectric constant and electrical susceptibility. Four different shapes regular tetrahedral, regular octahedral, regular hexahedral and spherical are considered for size and shape dependent study of mechanical and electrical properties of Ag, Al, Au, Ni, Bi nanometals and Si, Ge, CdS, ZnS, ZnSe semiconductors. This study reveals that the Young’s modulus of nanometals decreases with size decrement whereas, for semiconductors it shows inverse effect due to quantum confinement of charge carriers. Qi’s model has been found best suitable for mechanical study of nanometals. However Jiang’s model fits best for the semiconductor class. Shape and size dependent electrical study of semiconductors shows that band gap increases with size decrement whereas both susceptibility and dielectric constant show decrement. The outcomes acquired from present study have been compared graphically with available experimental and simulated data, which show a close agreement in between. Present study also reveals that shape effect is more prominent for small sized nanoparticles while its impact gets immaterial for higher sizes. This study is helpful in choosing the shape of the materials according to the requirement.ThesisItem Open Access Investigation of structural and elastic parameters of Nickel Ferrite by XRD and FTIR(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2020-11) Rawat, Nidhi; Dixit, GaganSpinel ferrites have been at the center of attraction for researchers since their discovery. The wide range of applications of nickel ferrite such as in spintronics, environmental protection, medical diagnosis, etc. makes it an important example of inverse spinel ferrites. In the present investigation, nickel ferrite nanoparticles were synthesized by chemical route method using citric acid. The formation of a single-phase spinel structure was confirmed by the X-ray diffraction pattern. FTIR spectroscopy confirmed the results obtained by XRD. The crystallite size estimated by Scherrer formula and W-H plot method was found to be 46 nm and 65 nm respectively. Despite the classification of spinel ferrites as normal, inverse, or mixed spinel, they can switch from one type to another depending upon synthesis conditions, crystallite size, etc. Therefore, the cation distribution study was done by comparing the experimental X-ray intensity ratios with the theoretical intensity ratios evaluated by the Buerger method. No conclusion could be drawn from this method so theoretical and experimental lattice parameters were compared to obtain the required cation distribution. Different structural parameters were calculated using XRD data and the effect of change in cation distribution on these parameters was also studied. Vacancy parameters were evaluated for quantitatively studying the occupancy of ions in the lattice. A method based on infrared spectroscopy was employed to evaluate elastic parameters. The change in cation distribution and crystallite size affected various elastic parameters. Rigidity modulus, elastic wave velocities, and Debye temperature were found to decrease when the size changes from bulk to nano. As the concentration of Nickel ions on the tetrahedral site increased, Young’s modulus was observed to decrease while the Bulk modulus increased. It was concluded from the present study that cation distribution and crystallite size affect the structural and elastic properties of spinel ferrites.ThesisItem Open Access Thermodynamic study of heavy metals adsorption on magnetite nanoparticles(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2020-12) Rana, Deepti; Singh, VirendraWaste-water is one of the most common reason for water pollution, may come from domestic, agricultural, and industries. Adsorption is considered to be one of the most effective technology, widely used for waste-water treatment. In the present work, magnetite nanoparticles were used for the removal of Cd(II) and Pb(II) metal ions from aqueous solutions at 4.2 pH and varying adsorbent amount. MNPs were synthesized by the co-precipitation method. To know the structural and magnetic properties, synthesized MNPs were characterized by XRD, FTIR, and VSM. Results of XRD and VSM revealed that the crystallite size of MNPs was 10.16nm and saturation magnetization was 56.42 emu/g. Adsorption experiment results showed that the capacity of MNPs is higher for Pb(II) ions. Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models were used to explain the adsorption phenomena for the removal of Cd(II) and Pb(II) metal ions. Results showed that the experimental data fitted very well for the Temkin isotherm model. With the help of these models thermodynamic parameters were determined, which revealed the nature of the process.ThesisItem Open Access Study of physical and radiation shielding parameters of erbium doped zinc boro-tellurite glasses(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2020-10) Gangwar, Rajat; Singh, VirendraIn this work, physical and radiation shielding parameters of Erbium doped Zinc Boro-tellurite (EZBT) glasses were studied. The glasses of composition 20ZnO- 25B2O3- (55-x) TeO2-xEr2O3 with x= 0, 0.5, 1.0, 1.5 and 2.0 in mol % were synthesized using melt-quenching method. These samples were characterized by different techniques i.e. Standard displacement technique, X-ray diffraction and FTIR to examine various properties. The values of density and oxygen packing density (OPD) were increased with increasing concentration of erbium while the molar volume was found to be decreasing with increasing concentration of erbium oxide. The amorphous nature of these glasses was confirmed by XRD technique. The mass attenuation coefficient ( ) of the samples was obtained using WinXCom software and other relevant relations were used to calculate the Half-value layer (HVL), Mean free path (MFP), effective atomic number ( ) and effective electron density ( ) in the energy 0.01 MeV− 10 MeV. Results showed that the shielding properties improve with the increasing amount of erbium oxide and the maximum values of and were found for 2.0EZBT glass sample. Also, that particular sample has shown the lower value of HVL and MFP, which results in more attenuation and thus better shielding features. The parameters at diagnostic energies (20 keV, 30 keV, 40 keV and 60 keV) were compared with lead glass and ordinary concrete. The outcome shows that all the glass samples are capable of replacing ordinary concrete and lead glass at 40 keV and 60 keV. Moreover, 2.0EZBT showed the best shielding performance among the selected glasses at medical diagnostic energies. Hence, the results of this current investigation are useful in designing the lead-free radiation shielding material in diagnostic radiology.ThesisItem Open Access Transmission coefficients for light projectiles based on global optical potentials(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2006-07) Dhyani, Pravesh; Agrawal, H. M.Present Work is motivated to compute transmission-coefficients for light projectiles (n, p, 2H, 3H, 3He and 4He) with the help of simple empirical expressions together with different global and specific optical potentials available in the literature. On the basis of parameterized expressions, an empirical fit has been proposed for neutron projectile, which is in better agreement with Wilmore and Hodgson‟s global potential compared to empirical expressions of Murthy et al. over the target mass range 20-209 and energy greater than 50 MeV (up to 100 MeV).ThesisItem Open Access Production of radionuclides 55,59,60 Fe in fusion reactor environment(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-07) Joshi, Vipin Chandra; Pandey, BhawnaImmense nuclear data is essential for the advancement of fusion reactors. Ongoing research investigations are on the way that will lead to a commercial fusion reactor. The study of radionuclides generated in the fusion reactor is of great importance. A lot of essential nuclear data can be extracted from the produced radionuclides in the reactor. Present research work is associated with the production pathways (inventories) and amount or activity of radionuclides of iron(55Fe, 59Fe, 60Fe) produced in the fusion reactor during its operation. The study is concentrated on production pathways and the cross section for the formation of radioisotopes 55Fe, 59Fe & 60Fe. These radionuclides are produced when a 14.1MeV neutron from the D-T plasma interacts with the wall material of fusion reactor. The Amount of these radionuclides produced through major pathways is calculated. The production cross sections via each pathway are calculated using the latest version of nuclear modular code TALYS-1.9. These cross sections are also compared with the experimental data available from EXFOR and evaluated nuclear data libraries. The pathway of maximum yield for the production of these radionuclides is identified. Some of the 14.1MeV neutrons interact with the reactor wall material and displace the atoms from their positions in crystal lattice, recoil spectra of daughter nuclei are crucial. Present investigation reveals that the radionuclides 55,59,60Fe are produced in the fusion reactor in sufficient amount that is harmful for the reactor health. The amount(activity) of radionuclides, major pathways, production cross section study is also included in details.ThesisItem Open Access Study of swift heavy Ion irradiation induced effect on Gadolinium doped Nickel Ferrite(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-07) Sidana, Upasana; Dixit, GaganSwift Heavy Ion Irradiation is very unique tool to modify the properties of material. Present work is an attempt to study the effect of 200 MeV Ag ion induced modification on structural and optical properties of 4% Gd doped Nickel ferrite nanoparticles. SRIM calculations showed that the electronic energy loss for 200 MeV Ag ions is much greater than threshold value. Therefore, columnar defects are expected to occur. The samples were synthesized by chemical route using citric acid. Structural and optical properties are studied using XRD, FTIR and UV-Vis Spectroscopy. XRD confirmed the cubic spinel structure of pristine and irradiated samples. After irradiation, crystallite size decreases while there is a slight increase in lattice parameter with increasing fluence. Lattice strain was found to increase with increasing fluence of irradiation. X-Ray Density does not change significantly at low fluences but decreases at high fluences which confirm the presence of defects in the sample after irradiation at high fluence. FTIR spectra also confirm pure spinel phase of the samples. Variation of FTIR band position and FWHM supports XRD result that significant changes in structural parameters can be observed at high fluence of irradiation. The reflectance spectra recorded by UV-Vis spectroscopy show two direct band gaps in all samples. The two band gap energies are due to the co-existence of high spin and low spin states. Both the band gaps were found to increase with irradiation fluence.
