Department of Physics

Permanent URI for this communityhttps://repository.cuilahore.edu.pk/handle/123456789/24

Browse

Has files: YesSubject: search.filters.subject.FA19

Search Results

Now showing 1 - 10 of 35
  • No Thumbnail Available
    Item
    Synthesis and Characterization of Metal Doped Kesterite (Cu2ZnSnS/Se) Derived Nanostructures as Light Absorber for Thin Film Solar Cell Applications
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Muhammad Yasir Yaqoob; CIIT/FA19-RPH-038/LHR; Dr. Samia Aslam; LHR TP 7265
    Kesterite materials (Cu2ZnSnS/Se or CZTS) exhibit encouraging potentials for energy conversion. In this study inexpensive, and cost-effective kesterite-derived nanostructures through metal doping in (CuZnXS, X=Ce, La, Mo) has been synthesized and test them as photo-absorbing materials for semiconductor-based thin- film solar cell applications. The photo-absorbance or light-absorption propensity of the photo-anode material in a solar cell is essential to the overall effectiveness of the solar cell. By adding a second layer of photo absorbance material, the photo-anode activity can be increased, which may also increase the amount of photogenerated electrons. Optical spectroscopy methods, such as UV-visible spectroscopy, is used to examine the photo absorption characteristics of the synthesized nanostructures. The optical band gap, % transmittance, extinction coefficient and refractive index of the kesterite material has been calculated and it was found that the band gap of the as synthesized kesterite material is varies in the range 1.125eV -1.5eV which is suitable as the absorber material for solar cell applications. The structural defects and recombination centers are examined using Photoluminescence spectroscopy. X-ray diffraction (XRD) and Raman Spectroscopy has been done to study the structure parameters and vibrational modes of the as synthesized kesterite material. The XRD patterns of the materials shows the formation of kesterite material with tetragonal structure for Ce-CuZnS and Mo-CuZnS and kesterite with monoclinic structure for La-CuZnS. The Raman spectra of all samples shows the characteristics modes of Cu- S, Zn-S and Ce2O, La-O and different modes of S-Mo-S in Ce-CuZnS, La-CuZnS, and Mo-CuZnS respectively.
  • No Thumbnail Available
    Item
    Synthesis and Investigation of Structural, Magnetic and Electronic Properties of Soft Ferrites: An Experimental and Density Functional Theory Approach
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) WASIF IRSHAD KHAN; CIIT/ FA19-RPH-018/LHR; Prof. Dr. Muhammad Asif; LHR TP 7673
    The structural, electronic and magnetic properties of nickel ferrite (NiFe2O4) are studied by employing both experimental as well as theoretical approach. Experimentally the sol- gel method was employed for the synthesis and different experimental characterizations such as XRD, FTIR, SEM and VSM were used to investigate its different properties. Theoretically we worked under the frame wok of DFT using CASTEP code and some approximations like LDA, LSDA and GGA. XRD confirms the fcc structure of sample with lattice constant of 8.20 Å belonging to space group fd-3m. FTIR spectrum revealed the absorption peak at 598 cm -1 which is due to octahedral site in the inverse spinal NiFe2O4. SEM was used for the investigation of surface morphology and showed the agglomeration with non-uniform particle sizes. The magnetic properties are derived from M-H loop using VSM which confirm the soft magnetic nature of the NFO with magnetic moment 2.63 . Theoretically DFT was used and all work done in CASTEP code using different approximations. It was revealed that LSDA failed to describe the magnetic structure of the present compound, that‘s why we move forward to use GGA which provide reliable results with best agreement with the experimental results like lattice parameters, Band gap, electronic and the magnetic properties
  • No Thumbnail Available
    Item
    Efficient Strategies to Enhance the Conductivity in Perovskite Materials for Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC)
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) MUBEEN YOUSAF; CIIT/FA19-RPH-055/LHR; Dr. Muhammad Ajmal Khan; LHR TP 7676
    Renewable energy sources are growing increasingly essential in this day. In order to avert climate change, they will play and expect a more important role in the near future. Fuel cells have gotten a lot of interest in this context because of their high conversion efficiency when compared to traditional energy conversion systems. Solid oxide fuel cells (SOFC) are one of the finest energy conversion technologies available, with minimal hazardous emissions, pollution, fuel adaptability, and expense materials properties. However, there are still some issues to be resolved; for example, the activity of SOFCs at low temperatures is reduced due to interfacial polarization blockages and also the oxygen reduction process (ORR). Lanthanum Iron Copper Oxide Cathode materials are created to increase activity and ORR. The cathode materials La1Fe1-xCuxO3–δ where x= 0.1, 0.3, 0.5 and 0.7 are synthesis by sol gel method. Their characteristics are investigated by various characterizations such as Raman Spectroscopy, Fourier Transformation Infrared Spectroscopy (FTIR), X-Rays Diffraction (XRD), and Electrochemical Impedance Spectroscopy (EIS). Prominent bands at peak positions 158, 290, 305, 960 cm −1 wavelengths are observed through Raman spectra of La1Fe1-xCuxO3–δ at x = 0.1, 0.3, 0.5 and 0.7 cathodes, analogous to lanthanum site vibration, typical stretching, symmetric stretching vibrations for Cu-O band, phonon mode, octahedral tilt vibrations, D band and associated with Ag and Bg double energy band. The prominent peaks at 675, 855, 1056, 1458, 1645 and 2830 cm -1 wavelengths observed through FTIR Analysis, these peaks attributed to stretching vibration of La-O bond, Cu-O stretching vibration, bending vibration of C-H in gaseous, asymmetric and symmetric O-C-O stretching vibrations, bending mode of H-O-H bond vibrations. XRD also provide crystal structure of materials. Two cards from La1Fe0.9Cu0.1O3–δ (JCPDS card number 96-100-8543) and (JCPDS card number 96-901-4244) have an orthorhombic structure. Two cards from La1Fe0.7Cu0.3O3–δ (ICSD card No 96-900-2333) and (ICSD card No 96-100-8573) shows an orthorhombic structure. Two cards from La1Fe0.5Cu5.5O3–δ (ICSD card No 96-901-5232) and (ICSD card No 96-200-2184) show an orthorhombic structure. Two cards from La1Fe0.3Cu0.7O3–δO3–δ (ICSD card No 96-100-8930) and xi (ICSD 96-200-1419) describe hexagonal and orthorhombic Structure. Electrochemical Impedance Spectroscopy is use to analyze the electronic and ionic behavior of the material. Material La1Fe0.3Cu0.7O3–δ has good electronic behavior and enhanced the maximum ORR of material.
  • No Thumbnail Available
    Item
    Synthesis of Zinc Ferrites and Carbon Dots Composite by Coprecipitation Method and Insight into the Physical Properties
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) M. Qamar Jahan; CIIT/FA19-RPH-022/LHR; Dr. Mukhtar Ahmad; LHR TP 7674
    Magnetic core-shell (zinc ferrites/c-dots composite are properly synthesized under this research using a simple co- precipitation and hydrothermal process. Various approaches are used to investigate zinc ferrites and carbon dots composites like X-ray diffraction (XRD), Scanning electron microscope (SEM), Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, and vibrating sample magnetometer (VSM). XRD diffraction demonstrated an inverse spinel structure of zinc ferrites; the lattice parameter was decreased from 8.19Å to 8.10Å and carbon dots having rods like structure. This provided excellent chemical stability for about 40 hours. From SEM analysis, the composite seem to be uniformly dispersed or coated using low contrast consecutive c- dots layers to produce a core-shell structure. Zinc ferrites are agglomerated in non- uniform in size, whereas carbon dots and its composites are in uniform shape according to SEM image. The EDX study indicated that the substitution was successful. For zinc ferrites, carbon dots and composite the FTIR spectra showed that the absorption band of the tetrahedral site is now around 654 cm -1 , 795cm -1 , 658cm -1 respectively. Different bonds in the infrared spectrum match to specific function groups and bonding in various chemicals. The magnetic characterizations were investigated using a vibration sample magnetometer (VSM) at room temperature (0 , and the results indicate that sample Zinc Ferrites/Carbon dots displays ferrimagnetic behavior.
  • No Thumbnail Available
    Item
    DFT Study of Diffusion Rate in Solid Electrolytes for Safe Design of Solid State Batteries
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Atiqa Razzaq; CIIT/FA19-RPH-005/LHR; Dr. Junaid Amjad; LHR TP 7704
    Lithium ion batteries(LIBs) are in high demand as energy storage media because of their high energy density, outstanding power density, and main feature is deliberate self- discharge rates. In point of fact, LIBs are leading the market of portable devices since their launch in the 1990. However, high emergent demand for large battery packs, especially those to be equipped on electric vehicles, requires severe safety concerns because of incapable electrolytes being more toxic and flammable. Solid state batteries are encouraging substitutions to LIBs and eventual key solution to the safety issues because of non-flammability of solid electrolytes which is the leading feature of solid electrolyte. The compatible potential between SEs and Lithium metal anodes and with high voltage cathode also lead to solid state batteries with higher energy density compared with conventional lithium ion batteries. So, solid-state batteries have been appealing wide attention for next generation energy storage devices due to the probability to realize higher energy density and superior safety performance compared with the state of art the art lithium ion batteries. However, the currently available SSBs have low performance due to slow ionic transport between SE and electrodes which leads to poor cycling stability. There are still many issues to be addressed to meet the industrially scalable solid state batteries. In the present thesis, the main focus is on the calculation of diffusion rate through solid electrolytes in order to get contribution in the research of finding the parameters which are involved in ionic diffusivity through solid electrolytes. Lithium argyrodite superionic conductor of the form Li7GeS5Br has shown great promise as a sulfide based solid state electrolytes due to high energy density and high diffusivity rate. In the present work simulation method is used to calculate the Li ions diffusion coefficient through solid electrolytes. Molecular Dynamics simulation is a powerful tool to study the diffusion coefficient through solid electrolytes. In this project, MD simulation is used to calculate the diffusion coefficient through Li7GeS5Br. With the help of MSD versus time plot the diffusion coefficient is calculated. Firstly, the structure of Li7GeS5Br is optimized. The optimized supercell was used as a benchmark model for subsequent calculations. During simulation process different trajectories of ionic movement have been collected in which lithium ions intra cage and inter cage jumps have been visualized. These detailed diffusion pathways and properties offer a throughout understanding of the diffusion process in solids and provide improved road map to design solid state batteries.
  • No Thumbnail Available
    Item
    Synthesis and Simulation of Titanium Dioxide Nanomaterials
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Safdar Anjam; CIIT/FA19-RPH-028/LHR; Dr. Muhammad Asif; LHR TP 7675
    In this work, the TiO2 nanostructures were synthesized by using the sol-gel method. The TiO2 has a wide bandgap, and its low work function makes it favorable as an electron transport layer for the application of perovskite solar cells (PSCs). During the synthesis of the TiO2 nanostructures, 7 ml of titanium tetra iso propoxide was used as a gel whereas the 60 ml isopropanol alcohol was used as a sol. TiO2 gel was obtained and dried at a temperature of 100ºC for 2 hours to make the powder form. Further, the TiO2 powder was dried via furnace for 3 hours at 550 oC to get the nanostructures of TiO2. A PSC is a kind of solar cell that includes a perovskite structured compound, most commonly a hybrid organic-inorganic lead or tin halide-based material, as the light-harvesting active layer. The active layer is sandwiched between a hole transport layer and an electron transport layer. Usually, a hole transport layer is a wide bandgap with high work-function material while the electron transport is a low work function and wide bandgap material. Even though perovskite solar cells' efficiency is as high as that of silicon solar cells, but the stability of the PSC is the main issue that needs to address for future enhancement of solar cells. In this project, we discussed various factors that influence the stability of PSCs.
  • No Thumbnail Available
    Item
    To Investigate the Radiosensitive Areas which are Affected in Treatment of Cancer under Radiation Therapy by using High Energy Photons (6-15) MeV
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) FARNAZ; CUI/FA19-RPH-059/LHR; Dr.NaimaAmin; LHR TP 7246
    It has been long known that patients treated with ionizing radiation carry a risk of developing a second cancer in their lifetimes. Factors that contribute to the restate of cancer( or may be called second cancer) includes improved cancer survival rate by using high radiations as well as emerging treatment modalities.These modalities such as intensity-modulated radiation treatment(IMRT) and proton therapy. They can potentially elevate secondary exposures to healthy tissues distant from the target volume. In this study; a high energy radiations (6-15) MV are used in the treatment of cancer. External beam radiotherapy is used to deliver the radiations to the organ. Pelvic organ selected as a target volume. The pelvic organs include surrounding tissues/OARs such as bladder, rectum, small bowl, LT and RT femoral heads. Thus the purpose of this study is to analyze and calculate the effect of high energy photons on these surrounding tissues of pelvic. There are many clinical situations in which radiobiological considerations can be usefully applied and all clinicians should be aware of the potential benefits of developing a quantitative radiobiological approach to their practice. Thus Mathematical & biological model (LQM) is used as a tool to calculate the Biological Effective Dose (BED) and Biological Equivalent Dose (EQD2) with dose per fraction 2 for different Organs at Risk (OAR’s) nearer to the pelvic. Moreover the aim of this study is to provide an understanding of the principles and methods related to scattered doses in radiation therapy by summarizing a large collection of dosimetry and clinical studies
  • No Thumbnail Available
    Item
    Synthesis of Metal-Organic-Framework Derived Materials for Energy Storage Applications
    (2021) Ayesha; CIIT/FA19-RPH-026/LHR; Dr. Muhammad Ashfaq Ahmad; LHR TP 7267
    With the progress in industrialization, the scarcity of resources and environmental pollution is growing fast. On the one hand, carbon dioxide produced by the ordinary combustion vehicle is a major source of global warming, where the fuel cars are accounted to consume a huge amount of oil resources. On the other hand, as the world has realized the importance of environmental protection, the development of a low- carbon transportation system has become an important solution. The electric vehicle has brought a lot of benefits, such as environmentally friendly, clean and no pollutant emissions. As a result, it might be regarded a potential new energy vehicle that has piqued the interest of consumers, industry, and researchers. Supercapacitors were also known as ultra-capacitors are being evaluated as one of the viable energy storage choices for future generations. These gadgets have been found to be useful in a range of applications, namely powering hybrid electric/electric automobiles and other electrical and electronic devices that enable energy to perform. Supercapacitors are the most flexible devices, widely used for supplying electrical energy quickly and in applications that need a long shelf life. As a result, there are considerable market demands for supercapacitors' development, and long-term advancement is necessary for their successful improvement and commercialization. New electronic and optoelectronic gadgets have recently grown on the market, requiring more dependable power sources with higher energy density and longer duration. Owing to their, pollution-free nature, stability, and high power density, supercapacitors have emerged as feasible options for energy storage. Traditional supercapacitors' poor energy density prevents them from being widely used, leading researchers to look into new forms of supercapacitors with better performance. Increasing the electrochemical performance of supercapacitors through the development of innovative electrode materials has been a major focus of study in recent decades. Asymmetric supercapacitors (ASCs) made consisting of two different electrode materials have a large working voltage window, enabling them to substantially increase energy density. In this research work, asymmetric super-capacitors electrode (ASCs) has been fabricated using Metal-Organic-Frameworks (MOF) derived mixed metallic oxides @CC as a positively charged electrode and MOF-derived nanoporous carbon (NPC) based material as a negatively charged electrode by a cost-effective hydrothermal method. The substantial materials are zinc-cobalt nitrates and 2-methylimidazole. The hydrothermal method is used to produce all samples.
  • No Thumbnail Available
    Item
    Synthesis and Characterization of Metal Oxide Based Photothermal Material for Interfacial Evaporation
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Azeem Sarwar; CIIT/FA19-RPH-031/LHR; Dr. Muhammad Idrees; LHR TP 7264
    With the fast growth of population and increasing environmental problems, resources. The shortage has drawn global concerns in recent years. Conversion of renewable energy sources like solar energy to generate other resources such as could be a promising strategy to solve the resources issues. Among them, interfacial solar steam generation arises to be an attractive strategy to generate freshwater by utilizing only solar energy. Utilizing solar energy to evaporate water is one of the greens and promising approaches in addressing the issues of global freshwater shortage and water pollution. Conventional solar steam generation systems usually involve bulk-water heating with low efficiency due to the considerable thermal energy loss. Recently, interfacial solar evaporation systems using floating evaporators to absorb heat at the air-water interface have received wide interest. A low-cost, efficient, and durable solar absorber is vital for the development of solar steam generation. This study focuses on photothermal materials for applications in solar-thermal conversion for freshwater generation. TiO2 and carbon materials have gained extensive research attention for solar steam generation owing to their non-toxic nature and environmental friendliness. In this work, TiO2-carbon nanocomposites were synthesized by hydrothermal method and employed as a solar absorber for enhancing water evaporation. Raman spectroscopy and FTIR use for structural and vibrational studies of TiO2-carbon nanocomposites.
  • No Thumbnail Available
    Item
    Comprehensive Study on Network Former Mixing Effect in Heavy Metal Based Oxide Glasses
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Manawal Shuja; CIIT/FA19-RPH-027/LHR; Dr. Junaid Amjad; LHR TP 7260
    Phospho-Tellurite glass with Ytterbium Yb+3 was prepared which is a rare earth to study the network former mixing effect in the prepared glass. The glass was prepared by melt quench technique in an electrical furnace at a temperature of 1100 °C. Glass were made in palettes of 2mm in size. The prepared glass was then characterized by using Raman, FTIR and UV-VIS (Reflectance) Spectroscopy. The Raman Spectra reveled that phospho-tellurite are suitable for Raman broadband Amplifiers. FTIR revealed the functional groups of glass and verified the presence of non-bridging oxygen atoms. Whereas UV-VIS (Reflectance) Spectra was used to calculate the band gap of prepared glass sample. The band increases from 2.7 eV to 3.25 eV which shows change in structure of tellurite from TeO4 to PO4 units by increasing amount of network former P2O5 gradually.