Department of Physics

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https://escholar.umt.edu.pk/handle/123456789/2036

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Browsing Department of Physics by Subject "M.Phil Thesis"

Now showing 1 - 5 of 5
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    Ab-initio study of LiTm2O4 (Tm=V, Mn, Fe, Co & Ni)
    (University of Management and Technology Lahore, 2017) Mohyuddin, Saima
    The transition metal spinel oxides as the electrode materials for lithium ion batteries have been inspected comprehensively lately with large capacity and high working voltage. The structural, electronic, thermoelectric and magnetic physiognomies of LiTm2O4 (Tm=V, Cr, Mn, Fe, Co, Ni) have been reconnoitered contained by the framework of density functional theory using the full-potential linear zed augmented plane wave method. The ferromagnetic ground-state energies have been premeditated by using the optimized structures. To compute the precise prophecy of the electronic and magnetic properties of LiTm2O4 (Tm=V, Cr, Mn, Fe, Co, Ni), the modified Becke-Johnson local density approximation functional is reachable. The half-metallic behavior in these compounds has been exposed by the electronic band structures and density of states plots, which is elucidated in expressions of exchange and crystal field splitting energies and magnetic moments. The key parameters for thermo electric response i.e electrical conductivity, thermal conductivity, see beck coefficient and power factor are studied in detail. The considered compounds of LiTm2O4 (Tm=V, Cr, Mn, Fe, Co, Ni) have been revealed theoretically that they grow potential spintronic and Li-ions batteries applications.
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    A density function theory study of the electronic and optical properties of cesium lead halide perovskites for potential application in solar cell
    (University of Management and Technology Lahore, 2016) Waqas, Muhammad
    The current study was planned to use WIEN2k code in order to calculate thestructural, electronic and optical, properties of the lead halide perovskites CsPbX3 (X = Cl, Br, I). Lead halide perovskites had attracted enormous attention as optoelectronic materials, because these materials have power conversion efficiency up to 20 %. So as to calculate the optical, structural, and electronic properties of cubic perovskites CsPbX3 (X = Cl, Br, I), full potential linear augmented plane wave (FP-LAPW) method was opted, that was based on density functional theory (DFT) within LDA, GGA-PBE and mBJ approximation. We have found a good agreement between experimentally measured values and theoretically calculated lattice constants. The perovskite compound CsPbX3 (X = Cl, Br, I) has direct and wide band gap located at point of R-symmetry, while the band gap decreased from ‘Cl’ to ‘I’ down the group,. The study of the densities of electrons has revealed strong covalent bonding between Pb and halides, while strong ionic bonding between Cs and halides. The reflectivity, refractive indices, absorption coefficients, real and imaginary parts of dielectric function, optical conductivities, and the other optical properties were calculated. Modeling of these perovskites compounds have direct band gap nature and high absorption power in visible-ultraviolet range that enabled to study the potential applications of these compounds in solar cell application.
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    The effect of grain growth of electrode material on power output of alkali metal thermal electric converter
    (University of Management and Technology Lahore, 2015) Anwar, Muhammad Talha
    The Alkali Metal Thermal Electric Converter (AMTEC) is one of the most desirable device for directly converting heat into electrical energy among the thermal convertors. Electrode and electrolyte, components of AMTEC play an impotent role in the degradation of power output. This research work is focused on the electrodes of the AMTEC. Power output can be controlled by improving electrodes of the AMTEC for the use of long time operation. The effect of time of operation of AMTEC when operated continuously for 150,000 hours is studied on the degradation power output. The power output declines as, the time of operation increases. This is because of the electrode material. The grain size of the electrodes material increases with time of operation. The grain size increment reduces the power output. We examine values of grain size by keeping time of operation the same but vary the parameter “a”, the grain size increases with the increases of “a”. The degradation of power output occurs 28 % after 150000-hour operation. It is observed R_f remains almost constant for all time operation for smaller values of a = 1.141 × 〖10〗^9 but for higher values of “a”, R_f start increasing rapidly. The parameter “a” has been usually treated as constant for all practical purposes. It is proportional to a product of M_0 and γ_s. The value of γ_s decreases as the temperature increases, whereas M_0 increases as the temperature increases. As the mobility parameter “a” remains constant to some extent. However, when the temperature goes very high the parameter “a” may not remain constant as the proportionality of “a” to M_0 and γ_s is not of the same order. At high temperatures one may out weight the other and thus “a” may not remain constant at advanced temperatures. This works through has been done at one temperature ≈ 1023 K but analyzed the effect of “a” on the grain size and thus on power output. Power degrades as the grain size increases. For smaller values of parameter “a” grain size remains almost constant for all time of operation. But for higher values of “a “grain size increases rapidly, no matter for how long the operation is supported. So the degradation of power depends upon the increase in grain size and for the larger values of parameter “a”.
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    Energy from Salt Gradient Solar Pond:
    (University of Management and Technology, 2016) Qaisar Abbas
    For the useful conversion of solar energy solar ponds are probably one of the simplest technologies available. Solar ponds have been used for many applications like conversion of solar energy into thermal and electrical energy. These conversions are economically viable and technically feasible particularly in Pakistan. Pakistanis an agricultural country and swirly facing waterlogging and salinity problem, which is a drag to economy. Almost 43% of the area in Indus Basin Irrigation System (IBIS) is classified as waterlogged having depth to water table less than 3m.To demonstrate the technical and economic feasibility of solar pond in Pakistanwater samples are taken from the villages near Hudiara drain Lahore. Then quality of water samples is tested and found highly saline. It is proposed to construct salt gradient solar ponds in villages near Hudiara drain Lahore by using saline water from the underground of the water logged area. By utilization of energy obtained from salt gradient solar pond, we can pump out the underground saline water and use that water for next solar pond, whose energy can be used again to repeat the same cycle. This may be continued till all the logged water is drained out. This way the logged and saline land can be turned into the land suitable for agriculture purpose.
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    Suppressing Air Pollution in Metropolitan City by Solar Chimney Using Helio-aero- gravity Principle
    (University of Management and Technology, 2015) Sumaira Yaseen
    Air pollution can be purified using solar chimney in a metropolitan city. Reduction of carbon dioxide (CO2) and sulfur dioxide (SO2) from the atmosphere play an important role in these purifications. In this study a chimney is proposed to be constructed in the heart of the town, where the most polluted air needs to be cleaned. The water is sprayed on the top of the chimney that makes the air cool and denser. The cooled denser air descends to the bottom of the chimney where air turbines are placed. This air starts the turbine to produce electricity. The air is then passed through the filters which capture the particulate. To remove the undesirable gases the appropriate chemical reagents are placed at the bottom. Various routes of capturing CO2 and SO2 from the air are discussed physically and thermodynamically feasible. It is explained how large scale collection of these gases can be made using different reagents such as (NaOH, KOH, K2CO3 and Ca (OH)2) as possible sorbent. The cost estimate and energy producers are briefly discussed. Other quantities involved during this process as gas uptake, liquid flow rate, air flow rate, air pressure drops are discussed. This technique, in particular, is applied to Lahore to clean its air. For that purpose the environmental data for Lahore metropolitan area has been collected and analyzed. By using solar chimney approximately 30% air pollution can be reduced in Lahore city.