Browsing by Author "Assistant Profesor"

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    Barium Hexaferrite: Synthesis and Microwave Properties
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Hina Saleem; FA20-RPH-031; Assistant Profesor; LHR TP 7989
    Barium hexaferrite (BaFe12O19) is a big saturation magnetization, high Curie temperature, large permeability, strong resistance, high corrosion resistivity, and good chemical stability are all characteristics of hard magnetic materials. In the present work, Barium hexaferrite has been created using the co-precipitation method (BaFe12O19). The effects of different synthesis parameterslike treatment time and treatment temperature on the structural (crystal structure and microstructure) properties of barium hexaferrite have been studied. The as synthesized magnetic material is characterized by different techniques. Fourier-transform infrared spectroscopy (FTIR) spectra is used to record to insight the functional bonding, while RAMAN spectra is analyzed to verify the structure of the prepared materialand UV-Vis spectroscopy is used look for the optical related properties of (BaFe12O19). In RAMAN analysis peaks from 600 to 400 cm-1 are due to A1g vibrations of Fe-O bonds at the octahedral 4f2, 2a, and12k sites. In FTIR the sample annealed at 1000oC and 1100oC, it was possible to infer from the curves that the peaks do not significantly change as the annealing temperature is raised., but a different transition percentage. The bands at, 1055cm-1 can be associated with the vibrations in the surfactant molecule and shows the C-H stretching. These changes in the structural parameters will be correlated to the associated changes in the electrical and microwave properties.
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    F(Q) Gravity and its Cosmological Implications
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Ayesha Mahmood,; FA20-RMT-005; Assistant Profesor; LHR TP 7913; Dr. Rabia Saleem Assistant Professor
    This thesis is devoted to study some cosmic aspects within f(Q) gravity in the context of two different models, the power-law model f(Q) = Q + αQ2, λQ0 and the exponential model f(Q) = Qe Q . To complete the target, a homoge nous and isotropic space-time under perfect fluid distribution is considered to develop the dynamical system of equations. We examine the behavior of each model byusing somecosmological parameters including, deceleration parame ter, square speed of sound, statefinder and Om(z)-diagnostic which give results that are compatible with the expanding phenomena of universe. The graphical analysis of square speed of sound justifies the unstability of first model while second model is stable. Using fixed point method, we construct the relevant autonomous system of equations to examine the stability of model for phan tom, vacuum, and non-phantom phases. Moreover the study of growth index of matter perturbation in this theory describes that the anisotropic stress is equal to unity, which is the same result obtained in general relativity