Department of Physics
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Item Investigation of Doped (III-V) Group Elements Emissive Layer for Visible LED Applications(2019) Aqsa Hashmi; CIIT/FA17-RPH-043/LHR; Dr. Farah Alvi; LHR TP 5728This study Sb2S3 was prepared by applying hydrothermal technique with different concentration of Ag as a doping impurity to improve its optical and electrical properties to be used in optoelectronics for LED applications. FTIR spectra was used to analyze the vibrations of chemical bonds present in the different groups in the sample. The intensity of the peaks is reduced with the increase in doping concentration, this is because the strength of chemical bonds decreases because of intermolecular transition of groups present in the sample. Optical properties were studied by UV-Vis and PL spectroscopy. UV-vis spectra was used to calculate bandgap that comes out between 2.5-1.9 eV. The bandgap was reduced with the increase in doping concentration of Ag which indicate its good compatibility for LED applications. IV measurements were used to analyze IV characteristics of the samples and to find out the turn on voltage of the device. SEM results were helpful in analyzing the surface morphology of the samples and measuring the particle size. The device was characterized by electroluminescence spectra which confirmed the red emission from LEDs having emissive layers of undoped and doped Sb2S3. So the materials have bright future for visibe LED applications.Item Synthesis of Nickel Oxide (NiO) Fluorescence Nano Quencher and Their Application in Aptasensing of Ochratoxin-A(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Aqsa Khan; FA17-RPH -042; Dr. Rizwan Raza; LHR TP 5727The fabrication of fluorescence based biosensor for the ultra-sensitive and selective monitoring of Ochratoxin-A in the food samples is very important these days. We demonstrate for the first time, the development of nickel oxide nanoparticles (NiO) quenching based aptasensing platform for the detection of target molecule (OTA). In this work, NiO quench the fluorescence of FAM-labeled aptamer. These quenched intensities were due to energy transfer processes to the metal nanoparticles. Conversely, increase in fluorescence quenching intensities with a decrease in the size of the nanoparticles which may be useful for the design of new analytical tool to detect the presence of target analyte. The structural properties of prepared nano materials were analyzed by X- Ray diffraction (XRD).Surface morphology of prepared metal oxide nano materials were studied by Scanning Electron Microscopy (SEM) and crystalline behaviors size/shape was analyzed by RAMAN spectroscopy. We have found the cost-effective, easy to use and affordable method to design aptamer based fluorescence quenching assay for the detection and early diagnoses of mycotoxins (OTA).Item Nanocomposites Anode Materials for Fuel Flexible Low Temperature Solid Oxide Fuel Cell(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Muhammad Shakeel; FA17-RPH-061; Dr. Ghazanfar Abbas; LHR TP 5735Broad efforts have been made to create multi-fuel-based low temperature solid oxide fuel cell that will directly utilize hydrocarbons to produce electric power. It is very difficult to work because of the C-H bond activation and its immensely slow oxidation reduction in the low temperature range from 300 to 600 °C. The structural and electrochemical properties of prepared anode materials Ba0.15Zn0.60Mn0.15-Ag0.10, Ba0.15Zn0.60Mn0.15 Cu0.10,Ba0.15Zn0.60Mn0.15-Fe0.10, have been investigated within the sight of hydrogen, natural gas and ethanol at a low temperature of 650 0C. Through sol gel process prepared anode materials are synthesized. The average crystallite size has been found in the range of 19-90nm by XRD. Conductivity is measured by four probe method. Maximum conductivity of 4.8 S/cm, 4.3 S/cm and 4.4 S/cm have been found by using silver, copper, and iron as a catalyst at a temperature of 600 °C, 550 °C and 580 °C respectively. The impact of prepared nanocomposite materials on the performance of solid oxide fuel cell is investigated. The power density of the cell at different fuels has been checked and measurements demonstrate it varies from 100 to 500 mW/cm2 at 650 0C among different fuels at the anode side. The present examination reveals that proposed anodes are promising multi-fuel material for low-temperature solid oxide fuel cell, and it doesn't have to change hydrocarbon fills to completely use the benefit of these cells.Item Synthesis And Characterization Of Lead Based(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Muhammad Faizan; CIIT/FA17-RPH-025/LHR; Dr. Muhammad Amir Razaq; LHR TP 5720To overcome the needs of energy the production and storage of energy has become the critical problem therefore most research topics around the world are related to the work on storage devices [1]. Lead acid batteries (LABs) are the most oldest among the secondary rechargeable batteries. The first lead acid battery was invented in 1859. In these days getting power for various applications from LABs has become a popular way. These batteries include two types of electrodes and an electrolyte. One of the electrodes is positive and the other is negative. The reaction between these components is the basic cause of the generation of power. Due to having fast response, high cyclic efficiency about (63-90%) and low cost these batteries playing a vital role in all type of industries [2, 3, 4, 5].Item Study of Shock Waves Structures in the Comet Halley Plasma(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Muhammad Abdul Ghani; CUI/FA17-RPH-014/LHR; Dr. Zahida Ehsan; LHR TP 5715Weak dust-acoustic waves (DAWs) are addressed in a nonthermal charge varying electronegative magnetized dusty plasmas with application to the Halley Comet. The dynamics of the nonlinear wave are governed by a Korteweg–de Vries Burger equation that possesses dispersive shock wave. A weakly nonlinear analysis is carried out to derive a Korteweg-de Vries-Burger equation. The weak magnetic field is responsible for the dispersive term, whereas nonsteady dust charge variation is responsible for dissipative term, i.e., the Burger term. The positive and negative ion nonthermality, the obliqueness, and magnitude of the magnetic field are found to modify the dispersive and dissipative properties of the DA shock structure. Our results may aid to explain and interpret the nonlinear oscillations that may occur in the Comet Halley Plasma.Item Oxygen Cyclotron Harmonic Waves in the Inner Magnetosphere(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Abdul Waheed; CIIT/FA17-RPH-037/LHR; Dr. Muhammad Jamil; LHR TP 5726The Banded emission of Oxygen cyclotron harmonic waves has been observed by Van Allen probes in the Earth inner magnetosphere. The general dispersion relation for electrostatic Oxygen cyclotron harmonic waves is derived by using Lerche-Newberger sum rule for Maxwellian and Kappa distributions. Oxygen ion kappa spectral index (𝜅𝑖𝑂) has a significant impact on the Oxygen cyclotron harmonic waves. The quasi Maxwellian behavior is being observed as 𝜅𝑖𝑂 ≥ 5. The curves shift toward the higher value of wavenumber, as the value of 𝜅𝑖𝑂 reduce. There is an increase in super-thermal particles as we reduce the value of 𝜅𝑖𝑂. By decreasing the value of 𝜅𝑖𝑂, the super-thermal particles reduce the frequency , 𝜔𝑝𝑒𝑎𝑘, where the group velocity vanish and the associated 𝑘𝑝𝑒𝑎𝑘 get increase. These cyclotron harmonic waves may be useful for the diagnostic for the velocity distribution characteristics. Oxygen cyclotron harmonic waves can be helpful for the diagnostic of Van Allen Radiation Belts.Item Polarization and Electrochemical Studies for Ethanol Liquid Fuel Cell(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Amina Sarfraz; CIIT/FA17-RPH-051/LHR; Dr. Muhammad Ashfaq Ahmad; LHR TP 5731This thesis is dedicated to the synthesis of silicon carbide and silicon carbide based composite as an effective anode material in ethanol liquid fuel cell. As fuel cell is an efficient device for its clean energy production. To enhance the efficiency of such type of clean energy devices an efficient electrode material is required for its proper working. In fuel cell there is also need to study the behaviour of liquid fuel as well as their performance by using proper electrode material and catalyst. Therefore in this research work Si-C composite was made by sol-gel method, SiC by hydrothermal technique while the catalyst material LiNiO was fabricated by solid state reaction method. To analyze the structural properties of the synthesized samples XRD has been carried out and find out the two phases in the case of Si-C composite and one phase in the case of SiC with average 39.40nm and 41.34nm respectively. SEM was carried out to study the morphological behaviour of the prepared samples and the SEM micrographs depicts that all the particles are homogenous and possess the porous structure which is the requirement of best anode material. Through FTIR spectra different types of stretching and vibrational bonding was studied and find out that there is different kinds of bonding like Si-O-Si, Si-C, C=O and Si-OH present in the prepared samples. For remaining characterizations the different compositions of Li0.2Ni0.8O+SiC was prepared. Conductivity and electrical bandgap for all compositions was measured by using 4-point probe and the maximum conductivity was observed by the LiNiO + SiC (1:0.3) and find out to be 1.34 Scm -1 at 650 0 C and the electrical bandgap is calculated to be 0.84 eV. Then the three layer fuel cell was fabricated by using prepared compositions as anode and SDC as electrolyte and LNCZ as cathode. The highest power density was calculated to be 30.46 (mWCm -2 ) by using ethanol as a fuel and 37.12(mWCm -2 ) by using hydrogen as a fuelItem Study of Doped Sb2S3 Sensitizer for Third Generation Solar Cell(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Muhammad Saqib; CIIT/FA17-RPH-013/LHR; Dr. Saif Ur Rehman; LHR TP 5714The dye-sensitized solar cell has been investigated as the most promising candidate for photovoltaic applications due to its unique properties, low cost and suitable power conversion for commercial purposes. In this dissertation the thin films of Sb2S3 are synthesized by hydrothermal method with different doping ratios of copper (Cu). The prepared material is further characterized by different techniques. UV-Vis is used to analyze the absorption spectrum of both doped and un-doped materials. The results show that the absorption spectrum have sharp edge close to the band edge which indicates that it has direct band gap. The band gap calculations are 2.01 eV in case of un-doped Sb2S3 and 1.32 eV to 1.45 eV in case of 3% - 5% Cu doping. This variation in band gap calculations can be attributed to change in film thickness and higher concentrations of Cu doping. FTIR is used to analyze the bond vibrations of different groups which are present in Sb2S3 with different Cu-doping ratios. The peaks in FTIR spectra indicate that the peak intensity is increased with 3% cu-doping but decreased with 5% Cu-doping. Raman spectroscopy is used to analyze the different frequency modes present in the material. The peaks at approximately 260cm -1 and 950cm -1 are representing the different symmetric and anti- symmetric Sb-S stretching present in the material. The SEM results show the spherical shapes of un-doped Sb2S3 nanoparticles having average size range 80 nm but in case of 3% Cu doping, the nanoparticles make clusters or bunches with each other which indicate that by doping with different Cu ratios, the structure have been changed. It has been observed that with 5% Cu and above the doping will agglomerate the material which is not feasible for solar cell applications. The maximum energy conversion efficiency is recorded 1.4% with 3% Cu doping having FF of 0.75, Voc of 0.70 V and Jsc of 27 mAcm -2 . The efficiencies of un-doped and 5% are recorded as 0.76% and 0.96% with different values of Jsc, Voc and FF. This variation of efficiency can be related to different grain size and chemical composition of materialItem Synthesize and Characterization of Rare Earth Doped Ferrites(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Ahad Ali Khan; CIIT/Fa17-RPH-018/LHR; Dr. Salman Naeem Khan; LHR TP 5718In this study, Yttrium doped Copper ferrite (𝐶𝑢𝐹𝑒2−𝑥𝑌𝑥𝑂4; 𝑥 = 0.1, 0.2, 0.3, 0.4, 0.5) were synthesized through sol-gel auto combustion technique. X-ray diffraction and scanning electron microscope is employed to carry out structural and morphological study of as prepared samples. The XRD patterns confirms the formation copper spinel structure, with increasing concentration of dopant induces an impurity phase of YFeO3. And SEM images display the spherical like particles with decreasing tendency ~ 2.14-1.28 μm. Vibrational modes were examined through Raman and FTIR Spectra. Observed 5 Raman modes of Γ = A1g + E1g + 3T2g affirm spinel structure with M-O bonding in undoped sample while increasing Yttrium concentration shifts the modes and increases the intensity of 3T2g mode at 512.5 nm. FTIR plot the site preference of metallic ions, Cu-O vibration at 651.5 nm corresponds to tetrahedral site. Dielectric and magnetic properties were investigated through Vector Network Analyzer, range from 1-6 GHz. The decrease in real permittivity from ~ 5-3 (F/m) as well as in real permeability ~ 2.5-1.75 (H/m) by increasing Y3+ content. This trend directly correlate with degree of crystallinity. The magnetodielectric properties are suitable for use in radar systems and shielding applications.Item Preparation and Characterization of Solid-State Electrolyte Material for Energy Storage Applications(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Muhammad Shahzad; CIIT/FA17-RPH-012/LHR; Dr. Junaid Amjad; LHR TP 5713Seven Boro-phosphate samples with composition (70 - x) B2O3 – 30 Na2O3 – xP2O5 where x=0.5%, 1%, 1.5%, 2% and 3, 5, 10 mole% and 0.02 g Er2O3 in extra were prepared using melt quenching method. From the results of X-ray Diffraction (XRD), it was confirmed that the structure of the samples was amorphous. Amorphous materials have open structure, so they can facilitate in the conduction. Samples were characterized by UV-Visible near Infrared (UV-Vis-NIR) spectroscopy. The spectroscopy was performed with wavelength ranging from 400 nm to 1600 nm to obtain the absorption peaks of the samples. Five absorption peaks were observed because of the transition from the ground state 4I15/2 to the different excited states. From the results, direct and indirect energy band gaps were calculated. Direct energy band gaps were in the range 3.59 eV - 4.18 eV. Indirect band gaps were in the range 2.92 eV - 3.95 eV. Refractive index was also calculated which was in the range 2.19 - 2.42. Photoluminescence was performed between 200 nm to 800 nm to observe the emission peaks of the samples. Two broad peaks were observed centred at 540 nm to 565 nm. These peaks were due to the transition from 2H11/2 → 4S3/2 and 4S3/2 → 4I15/2 respectively. Then Raman spectroscopy was performed on the samples between 200 cm-1 to 1600 cm-1. Under an excitation wavelength of 488 nm, characteristic Raman peaks of borate and phosphate were observed. Shifts and appearance of new bands were due to the replacement of borate with phosphate contents.