M.Phil / MS

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This collection archives the complete set of theses produced by students of the COMSATS University Islamabad, Lahore Campus.

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Analysis of (p,xn) and (α,xn) Reactions on Cd and Ag Targets for Production of 110mIn and 111In
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 0210) Nabeela Mehwish; CIIT/SP19-RPH-032/LHR; Muhammad Naveed Aslam; LHR TP 6372
The objective of this thesis was to compile and calculate the excitation functions of nuclear reactions important for production of the two important radioisotopes indium 110m and indium-111. Both radionuclides have potential for diagnostic procedures. In the present work cross section data for reactions induced by proton and alpha particles on isotopes of cadmium and silver were critically assessed. At first the experimental data were scrutinized for consistency, then compared with the theoretical calculations using three nuclear model codes which are ALICE-IPPE, EMPIRE and TALYS. Nuclear model parameters were adjusted to obtain better agreement between theoretical and measured data. Finally, a recommendation is given regarding the optimum energy range for the desired radionuclide through each reaction.
Study of Shafranov Shift by the Simplest Grad Shafranov Equation Solution for Various Tokamaks
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2012) Kanwal Zulfiqar; FA10-MSPHY-005; Dr. Muhammad Asif; LHR TP 3515
Plasma internal energy is not conserved on a magnetic surface if nonlinear flows are considered. The Magnetohydrodynamic equilibrium in an axisymmetric plasma is described by the Grad Shafranov equation in terms of the magnetic flux. A generalized Grad Shafranov type equation has been used. Specific functional forms of plasma internal energy and current are used. A simplest analytic solution of the Grad Shafranov equation is used. This solution is over constrained both in shape and in plasma current. We demonstrate that the Shafranov shift for this solution is independent of plasma current for various tokamaks. We studied the dependence of Shafranov shift on various plasma parameters and found that Shafranov shift depends on parameters such as major radius, minor radius, aspect ratio and inverse aspect ratio. The Shafranov shift shows a direct relation with major radius „ ‟. The value of Shafranov shift increases with the increase in value of major radius. Similarly for minor radius „a‟ there exist a direct relation between Shafranov shift and minor radius. And inverse aspect ratio „a/ ‟ is also varies directly with Shafranov shift. For the case of aspect ratio Shafranov shift is inversely related to the aspect ratio „ ‟
Study of Shafranov Shift by the Simplest Grad Shafranov Equation Solution for Various Tokamaks
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2012) Kanwal Zulfiqar; CIIT/FA10-MSPHY-005/LHR; Dr. Muhammad Asif; LHR TP 3515
Plasma internal energy is not conserved on a magnetic surface if nonlinear flows are considered. The Magnetohydrodynamic equilibrium in an axisymmetric plasma is described by the Grad Shafranov equation in terms of the magnetic flux. A generalized Grad Shafranov type equation has been used. Specific functional forms of plasma internal energy and current are used. A simplest analytic solution of the Grad Shafranov equation is used. This solution is over constrained both in shape and in plasma current. We demonstrate that the Shafranov shift for this solution is independent of plasma current for various tokamaks. We studied the dependence of Shafranov shift on various plasma parameters and found that Shafranov shift depends on parameters such as major radius, minor radius, aspect ratio and inverse aspect ratio. The Shafranov shift shows a direct relation with major radius „ ‟. The value of Shafranov shift increases with the increase in value of major radius. Similarly for minor radius „a‟ there exist a direct relation between Shafranov shift and minor radius. And inverse aspect ratio „a/ ‟ is also varies directly with Shafranov shift. For the case of aspect ratio Shafranov shift is inversely related to the aspect ratio „ ‟.
Investigation of Sr-substituted BaFe2O4 Synthesized by Sol-Gel Method
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) Jawaria Shaheen; FA15-RPH-010; Dr. Mukhtar Ahmad; LHR TP 6985
In the present work, Sr-substituted samples of single phase spinel mono ferrites with formula Ba1-xSrxFe2O4 (x = 0.00, 0.33, 0.67, 1.00) were synthesized using sol-gel auto combustion method. A sample with x = 0.00 was chosen to heat treat at different temperatures (at 100oC, 300oC, 400oC, 600oC and 700oC for 4h) in order to confirm the single phase formation of the samples. The sample heat treated at these temperatures was then investigated by X-ray diffraction (XRD) analysis. The results show that single phase sample can be successfully synthesized at a temperature of 600oC which is much lower than the same structured samples reported in earlier literature. All the synthesized compositions of these samples were then sintered at 700°C for 4h for better crystallinity. These samples were then investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometery (VSM), Vector network analysis (VNA). X-ray diffraction analysis reveals that single-phase monobarium ferrites can be obtained at 600°C-700°C temperature for 4h. From XRD patterns, different structural parameters such as lattice parameters (a,b,c), cell volume (V) and X-ray diffraction density as a function of Sr2+ ions at Ba2+ sites were calculated. Scanning electron microscopy results show that the grain size increases as the temperature is increased because it is well known that increased heat treatment promotes the grain growth in ferrites. Fourier transform infrared spectroscopy analysis gives us information about different groups of chemical compounds present in our material. From M-H loops of the samples (with x=0.0, 0.33, 0.67 and 1.00) measured by VSM, different magnetic parameters such as saturation magnetization (Ms), remanance (Mr), coercivity (Hc) and magnetic moment (nB) were calculated. The value of coercivity (Hc) increases as the Sr substitution was increased in ferrite materials. In addition, the variation of different dielectric parameters (real permittivity, imaginary permittivity, real permeability, imaginary permeability, ac conductivity and loss tangent) as a function of frequency (-6GHz) has been discussed in the present work.
Magnetosonic Weaves for Anisotropic Non- Extensive Distributions
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) MUHAMMAD ZEEWAQAR MANZOOR; CIIT/FA15-RPH-024/LHR; Dr. Muhammad Fraz Bashir,; LHR TP 6983
The magnetosonic wave instability is studied by using the kinetic theory taking the non- extensive anisotropic distribution which follows the Tsallis statistics. The temperature anisotropy may also serve as a source of free energy, which can make different waves unstable depending upon whether the anisotropy ratio is either greater (A>1) or smaller (A<1) than one. In this work, the marginal stability analysis of the magnetosonic wave instability in non-extensive anisotropic plasma is obtained using the exact numerical analysis to explain the Bale diagram obtained from the solar wind data at 1 AU for Non- extensive counterstreaming distribution. The effect of non-extensivity parameter q and the temperature anisotropy on the growth rate and the real frequency is discussed by using the exact numerical analysis. Different functional which depend on the counterstreaming parameter P have been considered. The appearance of counterstreams has a strong effect on the marginal instability conditions of the firehose and the mirror modes. The marginal instability conditions of these modes very precisely depend on the functional dependence of the parameter P. An extremely interesting new physical result has been obtained in the case P=P₁. In this case, the counterstreams affect both magnetosonic modes, making the plasma unstable at low values of ||  . With increasing the parameter P₀₁ the mirror and the firehose modes becomes more unstable, and the region of the plasma stability turns out to be limited from all sides. Such a behavior is obviously very similar to that found in the solar wind plasma, where the observed data form a rhombic-shaped region in the A- ||  plane. Thus the effects of Non-extensivity parameter q on the marginal stability curve are highlighted to better model the Bale- diagram Non-extensivity counterstreaming index q as compared to the usual Maxwellian distribution.
Electron transport properties of stacked 2 dimensional materials
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) Ali Raza; SP15-RPH-003; Dr. Abdul Sattar; LHR TP 6856
Graphene; a material with a high carrier mobility, having zero band gap drawback. Whereas, Boron Nitride with an insulating behavior, having a wide band gap opening. To control the band gap of grapheme without affecting the carrier mobility, Graphene/ Boron Nitride (grapheme/BN) hetero bilayers (HBLs) are formed. In these HBLs the layer of graphene is already doped with BN as well. First Principles calculations show that the band gap and electron effective mass can be modulated according to the need by just changing their stacking arrangement and the inter layer spacing between BN and hybrid layer of graphene. The results show that the tunability of graphene band gap have a linear dispersion relation with handsome band gap opening for a specific stable stacking pattern and this is a promising feature for futuristic Nano devices.
Synchronized Wastewater Treatment along with Electrons Recovery using Microbial Fuel Cell
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) Mahrukh Bukhari; CIIT/FA15-RPH-005/LHR; Prof. Dr. Saleem Farooq Shaukat; LHR TP 6933
The microbial fuel cell (MFC) was used to synchronize wastewater treatment with recovery of electric energy. This appears to give a potentially attractive alternative to traditional microbial fuel cell. This work focuses on a graphene oxide coated anode, and double-chamber MFC, with internal volume of 50ml of each compartment, operating in anerobic environment. The MFC was fed with urine as substrates. This study evaluates the MFC behaviour, in terms of COD, cyclic voltammetry and polarization curves. The cell has 13.4% treatment or COD removal efficiency, which shows that the microbes are metabolizing the organic matter present in the urine. In cyclic voltammetery results one major redox systems splits in to two redox system with time, which demonstrates that microbes are generating electrons. The system has 292 Ω an internal resistance and 0.19 mW/cm2 maximum power density for Graphene Oxide coated SST mesh anode. The Coulombic efficiency is found to be 73%, which shows the good result for electron recovery. In general, low COD content enhances coulombic efficiency.
Motion of Whiplash
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) ZANARA MUZAMMIL; CIIT-FA14-MSPHY-001/LHR; Dr. Shabana Nisar; LHR TP 6834
We propose to study the wave motions on a whip using numerical study of associated partial differential equations with specific goals of explaining the supersonic speeds of the tip, under various boundary conditions and structural parameters, which is responsible for the crack and concentrated damaging power associated with a whip lash. In light of above, the problem for us is to study the wave motion of the whip and construct a suitable mechanical model which can explain the main distinguishing feature of the whip i.e., high speed of the tip as well as study the motion of wave on the whip and study its general characteristics. We have found that the factors which are important in the crack of a whiplash are varying thickness of the lash, stiffness of the whip, and jerk applied to the whip. The mass of the whiplash plays very vital role in the motion of the whip. Usually the whip is thicker from the end which is attached to the handle and becomes thinner as we move along the lash towards the tip. The density will decreases as the square of the length across the lash for a linear decrease in the thickness of the lash. We find that this tapering of the thickness is crucial for the speed gain of the tip and higher variation cause higher speed gain and crack. It is also confirmed that a whip having some stiffness in its lash is more effective in producing higher speeds of the tip.In modeling an actual whip, we have also found that jerk plays very important role. The speed of the tip depends on the jerk given to the lash for wave motion. For the sudden jerk, the increase in tip speed is dramatic which has that cracking sound and the painful effect which we need.For out model the tip speed dramatically increase upto about 30-40 times than the speed at the starting point. This tip speed is on the top of overall motion of the whip. This speed crosses the speed of sound easily. Speed gain is 30-40 times at the tip. It is moving with very high speed that it can cross speed of sound, this is also called sonic boom. This high speed of the tip cause that excessive pain which we need to drive an animal
Synthesis and Characterization of Nickel-Copper Doped M-type Hexagonal Ferrites for High Frequency and Energy Storage Applications
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) Ahmed Iftikhar Qureshi; CIIT/FA15-RPH-031/LHR; Dr. Majid Niaz Akhtar; LHR TP 6832
Nanoparticles of Ni-Cu doped M-type hexagonal ferrites (Ba0.5Sr0.5NixCuxFe12-2xO19) have been prepared from Microemulsion technique. FTIR (fourier transform infrared spectroscopy), XRD (x-ray diffraction), SEM (scanning electron microcopy), VNA (vector network analyzer), UV-VIS (ultraviolet visible region) are used to characterized the materials for their structure, morphology, grain size and grain boundary, electromagnetic and optical properties of the M-type hexagonal ferrite sintered material. FTIR confirms the formation of M-type hexagonal ferrites that describes the bonding mechanism. XRD confirms the single phase crystalline material with ‘a’= 5.88 Angstrom and ‘c’=23.039 Angstrom. SEM shows a grain size of 0.25µm to 0.55µm, VNA confirm the dielectric and electric properties of M-type hexagonal ferrites. DC electrical resistivity and dielectric constant are increased which shows the material is a good candidate for high frequency and good capacitance for energy storage devices.
Ordinary Mode Instability in Non-extensive Anisotropic Plasma
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) MUHAMMAD SHERAZ MISALI; CIIT/FA15-RPH-001/LHR; Dr. Muhammad Fraz Bashir; LHR TP 6836
The distribution function has different forms in the different region of space plasmas. These change in the distribution significantly affects the dispersion properties of the waves especially their free energy source (if exist) can make the wave unstable under certain conditions. These instabilities as an effect of free energy source is a great deal of interest in space plasma community to their application to different solar wind problems e.g., particle acceleration etc. The non-extensive distribution have received renewed attention due to the better agreement with the space plasma observations as compared to the Maxwellian distribution. The temperature anisotropy makes the wave unstable based depending upon whether the anisotropy ratio (A=Tx/Tz) is either greater (A>1) or smaller (A<1) than one. The Bale diagram obtained by the solar wind data is clear indication of this relation showing four different region of anisotropy plasma beta space. These different regions are bounded by the instabilities. Davidson and Wu first discussed the electromagnetic ordinary (O) mode instability can become unstable for anisotropy ratio greater than one and high plasma beta. Ibscher et al. revisited the work and obtained the marginal and threshold conditions of the o-mode instability for electron for the bi Maxwellian distributions and extended to the solar wind proton anisotropy and related to the Bale-diagram. The exact numerical analysis contrary to the above theoretical result is predicted by Hadi et al. and clearly proved that the lower bound of the Bale-diagram is bounded by the O mode instability in the counter-streaming plasmas. In this work, the marginal instability threshold condition of ordinary mode(O-mode) is obtained using the exact numerical analysis to explain the bale-diagram obtained from the solar wind data at 1AU for Non extensive distributions. It is shown that the lower bound of the Bale-diagram is bounded by the O-mode instability. The effects of non-extensivity parameter q on the marginal stability curve are also highlighted to better model the Bale-diagram through Non extensity index q as compared to the usual Maxwellian distribution.
Direct Internal Reforming of Methane Fueled Solid Oxide Fuel Cell by Effective Catalyst
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) MUHAMMAD UMAIR; CIIT/SP16-RPH-001/LHR; Dr. Rizwan Raza; LHR TP 6994
Fuel cell is a device that produces power through chemical reaction without combustion. It is more effective among other source of energy. It is an environment friendly low or zero emission, high productivity, multi-fuel capacity, versatility. In this project, the work is done on the catalytic study of Solid Oxide Fuel Cell (SOFC). In SOFC, the most commonly materials are used ceramic based materials e.g. for electrolyte Yttria-Stabilized Zirconia(YSZ) but it require high working temperatures (700– 1000 °C) and can be keeping running on different fuels including natural gas. In this project, the electrode (LiNiCuZnFeO) is prepared by Solid State Reaction (SSR) method. The compatible electrolyte (LNK-SDC) is prepared by co-precipitation method. Three catalyst of different molar ratio of Barium Nickel Cobalt [Sample no.1 (Ba0.2Ni0.4CO0.4O3), Sample no.2 (Ba0.2Ni0.6CO0.2O3), Sample no.3 (Ba0.2Ni0.2CO0.8O3)] are prepared for direct internal reforming of SOFC using sol-gel method. Natural gas is used as a fuel for SOFC. The best performance of the cell is achieved at 650℃ with Sample no.2 (Ba0.2Ni0.6CO0.2O3) with maximum open circuit voltage (OCV) of 0.7V, current density of 250 mAcm-2 and power density of 64mWcm-2 with highest conductivity of 0.42 S/cm.
Study of the structural evolution in phosphate glasses using Molecular Dynamics simulations
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) Hafsa Javed; CIIT/FA15-RPH-002/LHR; Dr. Abdul Sattar; LHR TP 6843
This thesis presents the study of the structural changes in ternary zinc magnesium glasses. Compositional effects on the structural properties of the ternary zinc magnesium phosphate glasses were studied for the development of the glasses with the improved chemical durability. The basic methodology for the study is molecular dynamics simulations. The short range structures in glasses were examined using the pair distribution function, angular distribution function and coordination number analysis. Also the glass transition temperature was measured for different compositions. The short range structure of the simulated glasses was observed and the results were validated with the results obtained from simulations and the experimentally measured data. It was found that the backbone structure of the phosphate is not affected by the change in composition. As the zinc oxide was replaced by the magnesium oxide the chemical durability of the glass was increased. The results for the glass transition temperature show an increase in transition temperature with the replacement of MgO by ZnO. It indicates the formation of more chemically impervious bonds with increase in magnesium oxide content. The glass with the enhanced chemical durability will be more impervious to the aqueous attack.
The Effects of Mn –Substitution on the Structural and Magnetic Parameters of Zn Ferrites Synthesized by Sol Gel Method
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) Khursheed Amin; CIIT/Fa15-RPH-015/LHR; Dr. Abdul Sattar; LHR TP 6844
Single phase Mn substituted Zn ferrites with chemical formula Zn1-xMnxFe2O4 (x= 0.0, 0.1, 0.2 and 0.3) were synthesized by means of Sol-gel auto-combustion technique. The samples were sintered at 700oC and then characterized by different experimental techniques such as X-ray diffraction (XRD),Fourier transform infrared spectroscopy(FTIR),Scanning electrons microscope(SEM),Vibrating sample magnetometer(VSM) andVector network analysis (VNA). The single phase formation of all the samples was confirmed by the XRD analysis. Lattice parameter (a), volume (V) and X-ray density (Dx) as a function of Mn contents were calculated from XRD patterns. Scanning electron microscopy reveals that the grain size of all the ferrites is found to be in the range of 200nm-250nm. FTIR spectra give us idea about different functional groups present in a material and nature of molecular bonds in the substance. Vibrating sample magnetometer (VSM) was used to determine M-H loops of all the samples. The value of coercivity is found to be several hundred oersteds which indicate that the material is soft spinel ferrite in nature. In addition, high frequency parameters (direct and real permittivity, permeability, conductivity and loss tangent) were studied as a function of frequency (1GHz-6GHz) for a selected sample.
DEVELOPMENT OF ELECTRODE MATERIALS FOR FUEL CELL USING PULSED LASER DEPOSITION
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) IMRAN ALI; CIIT/SP15-RPH-012/LHR; Dr. Rizwan Raza; LHR TP 6845
The prevailing energy crisis in the world has to be tackled by employing sustainable energy sources. In recent years, research has been conducted on solid state ionic devices such as fuel cells, lithium ion batteries and solar cells which could be the future alternate energy storage and conversion technologies with no environmental issues. It has been observed that solid oxide fuel cells SOFCs with electrodes layers on electrolyte using Pulsed Laser Deposition PLD as compared to other fuel cells yield better results i.e. they can operate at intermediate temperature have high conductivity and enhanced power density. This thesis gives an approach to develop nanocomposite electrode materials for SOFCs to lower the operating temperature of SOFC. Lithium Nickel Copper Oxide (LNC), Lithium Nickel Copper zinc Oxide (LNCZ) and Samarium doped Ceria (SDC) nanocomposite have been synthesized using solid state reaction method and wet chemical method. The structure and morphology of nanocomposite electrode was examined by X-Rays Diffraction (XRD) and scanning electron microscopy (SEM). Atomic Force Microscopy (AFM) is used to examine the roughness and surface morphology of pulsed laser deposited film. The fuel Cell Performance was tested at temperature (550-7000 C). The Conductivity of the sintered nanocomposite measured by a two probe DC method. XRD pattern of the samples show that the materials are nanostructures. SEM images expose the morphology of materials which are homogenous and porous. Electrochemical study of synthesized fuel cell shows a mixed conductivity of 1.3 Scm-1 at 6500C. The electrochemical Performance of LNC/SDC/LNC configuration was measured with OCV 0.80V, Current density 400 mAcm-2 and power density 108 mW/cm2 with hydrogen fuel at 6500C. Whereas OCV 0.80V, Current density 408mAcm-2 and power density 118 mW/cm2 were observed at 6500C for LNCZ/SDC/LNCZ configuration using hydrogen as fuel and air as reduction agent at cathode terminal.
Atomistic simulation of silica-based glasses using molecular dynamics
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) Muhammad Umer; CIIT/FA15-RPH-026/LHR; Dr. Abdul Sattar; LHR TP 6842
Silica based glasses are being utilized ubiquitously in different disciplines of everyday life. Addition of modifiers in silica based glasses varies their physical and chemical properties. In this dissertation the preparation of silica based ternary glasses SiO2 CaO-ZrO2 using molecular dynamic simulation has been done. The structures of different silica based glasses with compositions 70SiO2-(30-x)CaO-xZrO2 (x=0,5,10,15,20,25,30) were generated using MD simulations following melt quench method. Pedone‟s potential is used to meet the requirement of molecular dynamics simulations. The radial distribution function analysis suggests that the clustering of the silica tetrahedral glass network increases with the concentration of calcium. The different concentrations of CaO and ZrO2 noticeably change the glass transition temperature of different compositions of glasses. The structural analysis of our ternary glasses equips us with the information of oxygen-silicon coordination number and the Qn species found in the prepared glasses. The appearance of different ratios of Qn species in our glasses is because of the changing concentration of CaO and ZrO2 in the composition.
Fabrication and Characterization of Tin Oxide Based Flexible Composites for Energy Storage Applications
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) NAEEM MUNIR; CIIT/FA15-RPH-030/LHR; Dr.M Aamir Razaq; LHR TP 6986
Tin Oxide (SnO2) is excessively used for energy storage applications due to wide potential, transparency and thermal stability. Several methods are reported for fabrication of SnO2 nano structures e.g. electro spinning, chemical vapor deposition process, self assembly, homogeneous precipitation method, thermal decomposition and hydrothermal method. Hydrothermal method is advantageous due to low cost, template free, environment friendly and low temperature. In this study, SnO2 is fabricated via hydrothermal method and furthermore composites with CuO, ZnO and lignocelluloses fiber are synthesized for development of electrochemically efficient and flexible paper electrodes for energy storage. X-Ray diffraction, Scanning Electron Microscopy (SEM), FTIR and Cyclic Voltammetry measurements of fabricated composites were employed to characterize the morphology, structural and electrochemical characteristics. SEM reveals the nano-petal and nanorods morphology of SnO2 and CuO, respectively. XRD measurements confirm the fabrication of SnO2, SnO2/CuO and ZnSnO3 by JCD cards (41-1445), (48-1548) and (34-1451) respectively. Cyclic Voltammetry confirm the electrochemical kinetics of fabricated composites which are highly feasible for super capacitors and batteries.
Flavor symmetry in D meson decays
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) Waleed Mustafa; CIIT-SP15-RPH-008/LHR; Dr. Shabana Nisar; LHR TP 6940
This thesis consists of the study of the D-meson decays using flavor symmetry. The research involves SU(3) symmetry analysis of the flavor diagrams to relate D-meson decays in the Cabibbo suppressed sector. Feynman Diagrams have been considered that express amplitudes for different decay modes in terms of Tree, Annihilation, Color suppressed and Exchange amplitudes. The decay rates have been then compared to the observational values to see if SU(3) symmetry approach can be used to describe the Cabibbo suppressed D-meson decays. Similar analysis has been done for the Cabibbo favored decays as well. In both cases, especially in singly Cabibbo-suppressed decays, SU(3) flavor symmetry breaking has been observed
Effect of Changing Fundamental Constants on Helium Abundance during Big Bang Nucleosynthesis
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) Raza ur Rehman Mir; CIIT/FA15-RPH-033/LHR; Dr. Shabana Nisar; LHR TP 6941
Effect of Changing Fundamental Constants on Helium Abundance during Big Bang Nucleosynthesis
Theoretical and Experimental Study of Mixed Ionic Electronic Materials (MIEC) for Electrochemical Functional Nano-Composite Layer
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2017) Muhammad Khurram Qureshi; CIIT/FA15-RPH-014/LHR; Dr. Rizwan Raza; LHR TP 6984
Due to the increased demand of energy there would be a stern dispute in the near future as the efficient energy resources are soon to be ceased. To overcome such a challenging disagreement, we have to put our attention towards such novel energy conversion and efficient technology which can strengthen us against such problem. Fuel cells are promising devices for clean and efficient power generation. The electrolyte free fuel cell (EFFC) is an innovative, high-energy conversion and efficient generation of fuel cells which directly convert the chemical energy into electrical energy. In this research the mixed ionic and electronic conducting material will be equipped by desired route for EFFC production. MIEC is basically responsible for the performance of EFFC. EFFC with only one homogenous layer Nano-composite material comprises upon ionic and electronic conductors which will overwhelm the mechanically and chemically compatible issues. The designed material was examined experimentally and theoretically. The single homogenous layer consist upon mixed conducting Nano-composite material certifies the better performance, high efficiency and reliability. Diverse electrochemical measurements are used to investigate the performance and efficiency of prepared EFFC material. The conductivity of MIEC is investigated with 2 probe and 4 probe method. After that, the mixed conductivity was separated out with the help of ion blocking and Heb-Wagner method. These two techniques were used to study the ionic and electronic conductivity of MIEC. Similarly, the optical, mechanical, vibrational, structural characteristics and important parameters were investigated with the help of multiple techniques The working and electrochemical performance of prepared EFFC was studied at Nano level to explain the working principle of as prepared EFFC. Theoretical model and simulations of p
Development and Electrochemical Characterization of Nanocomposites for Biogas Based Fuel Cells
(2018) Asia Rafique; CIIT/FA13-PPHY-003/LHR; Dr. Rizwan Raza; LHR TP LHR TP 5602
There is an urgent need to explore affordable and renewable energy resources because of the decline in reserves of fossil fuels. Biomass is an abundantly available resource in nature and can be used to generate energy in a sustainable manner. Fuel cells deliver a combination of advantages and make use of renewable energy sources. Solid oxide fuel cells (SOFCs), specifically, overcome the petroleum scarcity issue by using biofuel. The aim of this thesis is the development of nanocomposite electrolytes and anode composite catalysts for low-temperature SOFCs fuelled with biogas for clean energy applications. In the present work, Sr/Sm-doped ceria (Sr-SDC) nanocomposite electrolytes with a core shell structure are synthesized with different compositions for low temperature SOFCs. A co-doping technique is successfully used to achieve a significant enhancement in the ionic conductivity of 0.50 S/cm at 600 ˚C for the nanocomposite electrolyte Sr0.1Sm0.1Ce0.8O2-δ-carbonate. The carbonate phase (shell layer) acts as a barrier and protects the SDC (core) from the partial reduction by the fuel. This carbonate shell introduces an interface between these two phases, which is the key to realizing the interfacial super-ionic conduction pathways. This work also describes the development of ceria electrolytes that are doped and co-doped with lanthanum (La) and zirconium (Zr) and show excellent thermal stability. The ionic conductivity of La0.2Ce0.8O2-δ (LDC), Zr0.2Ce0.8O2-δ (ZDC) and Zr0.2La0.2Ce0.6O2-δ (ZLDC) has been measured in the temperature ranges of 450 °C to 650 °C and LDC achieved a high ionic conductivity of 0.81 × 10-2 S/cm. Thermal expansion coefficients (TECs) of these electrolytes have also been found to have good concurrence and compatibility with commonly used electrolytes and electrodes. The main objective of this work is the development of stable and active anode catalysts that run over biogas as well as hydrogen for low temperature SOFCs. The anode composite Ni0.6Zn0.4- Gd0.2Ce0.8O2-δ (NiZn-GDC) has been developed that exhibits semiconductor conductive behaviour, and a maximum conductivity of 1.37 S/cm has been achieved at 600 ˚C. This composite anode is found to have excellent thermally stability as well as being carbon resistant to coking during testing with biogas. A maximum power density of xii 820 and 548 mW/cm2 has been reported with hydrogen and biogas fuels, respectively, at 600 ˚C. This thesis also describes Ni-based and Ni-free anode catalysts NiLiCu-oxide with LDC for SOFCs fuelled with biogas. The anode composite NLC622-LDC has reported a maximum DC conductivity of 3.47 S/cm with Pmax of 650 and 390 mW/cm2 for hydrogen and biogas, respectively, at 600 ˚C. A Ni free anode catalyst Zn0.2Li0.2Cu0.6O2-δ (ZnLiCu-oxide) is also developed as a potential candidate for biogas-based SOFCs that bypasses the difficulty of carbon deposition and has a maximum conductivity of 4.0 S/cm at 600 ˚C. An open circuit voltage (OCV) of 0.96 V is achieved with maximum power density of 600 mW/cm2 with biogas (50% methane) at 650 ˚C. In the present work, a theoretical model of FC system has been designed using MATLAB software, and it makes use of biomass (animal waste, redwood, rice husk and sugar cane). In the last part of the thesis, a partial research work has been conducted to cast the tapes of NiO-GDC (NiO-Gd0.1Ce0.9O1.95) as anode and GDC (Gd0.1Ce0.9O1.95) as electrolyte via aqueous tape casting method. The aqueous tape casting is an emerging and cost-effective technique for the commercialization of SOFCs but faces challenges with ceria tapes due to its poor mechanical strength and co-sintering of half-cells.