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ThesisItem Open Access Development of unified model for the size and shape dependent properties of nanomaterials(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-11) Chhabra, Hina; Munish KumarIn 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.ThesisItem Open Access Comparative study of Bell's states(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-08) Airy, Balwant Singh; Johri, U.C.I have studied the effect of one and two sided amplitude damping, phase damping and depolarization channels on the Bell’s states. I found that in the case of two sided amplitude damping second state protects more entanglement compared to the first state and in the case of one sided amplitude damping both states protect the same amount of entanglement. In the case of one or two sided phase damping both the Bell’s states protect same amount of entanglement. In the case of two sided depolarization channels both the Bell’s states protect the same amount of entanglement while in the case of one sided depolarization channels, second state protects more amount of entanglement compared to the first. Ihave used weak measurement and quantum measurement reversal to protect entanglement against amplitude damping. I found that by using one or two qubit weak measurement and quantum measurement reversal entanglement can be protected effectively. Either in the case of two qubit weak measurement and quantum measurement reversal or one qubit weak measurementand quantum measurement reversal, second state is more protected as compared to the first state. I also studied the effect of correlated amplitude damping on Bell’s states and found that the memory parameter plays an important role. It helps in the protection of entanglement. I found that in the case of correlated amplitude damping, second state protects more entanglement as compared to the first state. As in the case of amplitude damping, weak measurement and quantum measurement reversal can be effectively used to protect entanglement.I found that in the case of two qubit as well as one qubit weak measurement and quantum measurement reversal, second state protects more amount of entanglement as compared to the first state.ThesisItem Open Access Thermal and electrical behaviour of nanomaterials under the influence of size, shape and pressure(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-08) Pachauri, Uma; Joshi, Depika P.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.ThesisItem Open Access Neutronics study for materials of interest in fusion technology(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-02) Pandey, Jyoti; Agrawal, H.M.ThesisItem Open Access Dynamics of quantum correlation in presence of environment(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-01) Awasthi, Natasha; Johri, U.C.We establish uncertainty relations between information loss in general open quantum systems and the amount of nonergodicity of the corresponding dynamics. The relations hold for arbitrary quantum systems interacting with an arbitrary quantum environment. The elements of the uncertainty relations are quantified via distance measures on the space of quantum density matrices. The relations hold for arbitrary distance measures satisfying a set of intuitively satisfactory axioms. The relations show that as the nonergodicity of the dynamics increases, the lower bound on information loss decreases, which validates the belief that nonergodicity plays an important role in preserving information of quantum states undergoing lossy evolution. Considering a model of a central qubit interacting with a fermionic thermal bath its reduced dynamics is investigated for the information loss and nonergodicity. Recently, it was argued that the binegativity might be a good quantifier of entanglement for two-qubit states. Like the concurrence and the negativity, the binegativity is also analytically computable quantifier for all two qubits. Based on numerical evidence, it was conjectured that it is a PPT (positive partial transposition) monotone and thus fulfills the criterion to be a good measure of entanglement. This investigation shows its behaviour under noisy channels which indicate that the binegativity is decreasing monotonically with respect to increasing noise. Binegativity is closely connected to the negativity and has closed analytical form for arbitrary two qubits. Our study supports the conjecture that the binegativity is a monotone. The effect of correlated Markovian noise channels on the quantum speed limit of an open system is examined. This is done for correlated dephasing and amplitude damping channels for a two qubit atomic model. Our model serves as a platform for a detailed study of speed of quantum evolution in correlated open systems.ThesisItem Open Access Study of electrical and magnetic properties of cobalt based metallic glasses and composite material(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2005-07) Agrawal, Rati; Kushwaha, R.P.S.There are many materials of commercial importance; composite materials and metallic glasses are two such important materials among them. Wide variety of technological and industrial applications of these materials motivates the present work. Cobalt based metallic glass of nominal composition Co60B12Si12Fe4Mo2Ni1 and cobalt based composite material prepared by varying concentration of cobalt metal powder in plaster of paris was used for investigating their electrical and magnetic properties. For cobalt based composite material change in A.C. magnetic susceptibility with both frequency and concentration have been taken into account. Similarly temperature and concentration dependence of electrical resistivity of composite material was investigated. From experimental results obtained, A.C. magnetic susceptibility was found to decrease with frequency for all concentrations and increase in susceptibility was observed when plotted with concentration. when electrical resistivity of cobalt based composite material was investigate for its temperature dependence, slight decrease in resistivity or a dip was observed for all the concentrations i.e. for all the samples with different concentrations of cobalt metal powder in plaster of paris. Energy losses in the samples were also measured by studying their hysteresis loops for two different frequencies.ThesisItem Open Access Dielectric study of nematic (4-Cyano- 4’-Pentylbiphenyl) liquid crystal(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-08) Ramnivas; Goel, PujaDielectric studies of the liquid crystals are important as they provide useful information about molecular structure, molecular dynamics, phase transition and display performance of liquid crystals. Present thesis work deals with the investigation of dielectric parameters of nematic (4-cyano-4’-pentylbiphenyl) liquid crystal over a wide range of frequency (100Hz- 10MHz) at different temperatures ranging from -100C to 500C. The fabrication of liquid crystal cell was done by using the photolithography technique. For the measurement of dielectric properties parallel plate capacitor cell was used. The area and separation between the plates were taken 35.54mm2 and 14.3μm respectively. The resistance of electrode wires was very low and was soldered with the help of USS 9200 ultrasonic soldering unit. All the dielectric measurements were performed using an HP 4192A impedance analyzer. The cells with the material under the study were placed with in a Linkam hot stage (THMS 600) controlled by a Linkam temperature for insuring the desired temperature for the measurements. As a result, at low frequency, the magnitude of dielectric permittivity was found to be increased with an increase in the temperature but at the higher frequency, it was decreased. At low frequency region, the magnitude of dielectric loss increases with increase in the temperature, after attaining maxima it is decreases. It was also observed that the transition temperature from nematic to isotropic phase was 320C.ThesisItem Open Access A preliminary study on the effect of Copper nanoparticles on certain pesticides(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-07) Ashneet Kaur; Goel, PujaNanoparticles are gaining a lot of attention worldwide owing to their unique physical and chemical properties, high surface area and nanoscale size etc. Present thesis work deals with the synthesis and application of Cu NP’s. In order to obtain stable, controlled size and size distribution, Cu NPs were synthesized via chemical reduction method by controlling various reaction parameters. The synthesized nanoparticles were used to prepare stable suspension of nanoparticles. Further, suspensions of NPs were also prepared using as procured Cu NP’s by optimizing the amount of different solvents viz. acetonitrile, isopropanol, kerosene and transformer oil and surfactant i.e. oleic acid. The prepared nanosuspension were characterized using UV-VIS and FTIR spectroscopy which confirmed the formation of stable Cu nanosuspension. It turned out that Oleic acid, used in specific amounts, can act as an excellent surfactant for Cu NPs however, it was not sufficient to prevent the oxidation of NPs. To study the application of Cu NP’s in pesticide degradation, solution of different concentrations of chlorpyrifos, dichlorvos and endosulfan were prepared. The prepared pesticide solutions were added to specific amounts of Cu nanosuspension and monitored with time. Change in colour was observed for all the samples giving a colorimetric method to study the effects of NP’s on pesticides. The reaction products of pesticides were characterized using UV-VIS and FTIR spectroscopy. The UV-VIS plasmon of nanosuspension showed red shift while the absorbance band of pesticides disappeared after reaction. The FTIR spectra confirmed the degradation of organic bonds of the pesticides. The pesticides have been successfully degraded by Cu NP’s as a result of their adsorption on NP’s surface and interaction between them.ThesisItem Open Access Excitation function of 55, 56 Fe (n,p) and 59,60 Ni (n,p) for surrogate technique(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-08) Joshi, Himanshu; Pandey, BhawnaFusion contains enormous amount of energy. ITER is the first thermonuclear reactor. In the critical components of the reactor, modified stainless steel is used, which have the composition of Iron, Nickel, Chromium, Molybdenum and others in order to enhance the properties of the steel. The fast neutrons of 14MeV emitted from the fusion reactor open various neutron induced channels. But inside the reactor various unstable radionuclides are produced through several inventories which have very short half life.. Cross section of any nuclear reaction gives the probability of that reaction. The study of 55,56Fe(n,p) and 59,60 Ni(n,p) cross sections of these radionuclides formed is useful for fusion reactor interest. Due to unavailability of the target nucleus, direct calculation of cross sections of these nuclei is difficult. So we use indirect Surrogate method to measure the cross section of these nuclides. For surrogate of any reaction to be possible, the reaction should proceed through compound nuclear reaction mechanism. The Excitation Function of any nuclear reaction shows the graph between cross section of the reaction and energy of incident projectile. For reaction to proceed largely through compound nuclear reaction mechanism, the contribution of compound nuclear reaction mechanism should be maximum in total cross section of the reactions. The excitation functions of the reaction 55,56 Fe(n,p) and 59,60 Ni(n,p) are plotted using TALYS 1.9 using the keyword “components” in the TALYS to verify the maximum contribution of compound reaction mechanism. Surrogate reactions for 55,56Fe(n,p) and 59,60 Ni(n,p) are formulated and the calculation of reaction rate is also done for the optimization of the input parameters of the surrogate reactions.