Browsing by Author "Dr. Muhammad Yasir Rafique"

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    Hydrothermal Synthesis, Structural and Electromagnetic Properties of Mn Substituted Ni Ferrite Nanoparticle
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2020) Sumaiya Sibtain; CIIT/FA18-RPH-043/LHR; LHR TP 6096; Dr. Muhammad Yasir Rafique
    Synthesis, Structural and Electromagnetic Properties of Mn Substituted Ni Ferrite Nanoparticle Manganese substituted nickel ferrite nanoparticles (MnxNi1-xFe2O4) have studied in this research work. Hydrothermal Method is used to synthesize all the samples at 200℃ for 12 hours. The effect of manganese substitution on particle size, structure, electric and magnetic properties has been investigated by X-Ray Diffraction (XRD) and Vibrating Sample Magnetometer (VSM). X-Ray diffraction shows that all the sample (x=0, 0.6, 1) peaks have cubic crystalline structure. Crystallite size calculated by Debye Scherer’s formula. Average crystallite size is found by 25.96nm-47.3nm. The peak position (2θ) of the samples shifted to lower angles by substitution of manganese in nickel ferrite. Substitution of manganese in the nickel ferrite increases the lattice constant and decreases the crystallite size. Increase in lattice constant is due to the larger ionic radii of manganese replaced by smaller ionic radii of nickel. Growth rate is very fast at (x=0), further increase in substitution of manganese in the nickel ferrite decreases the growth rate at (x=1). Magnetic properties are measured by VSM at room temperature. Hysteresis loop is used to measure the magnetic parameter such as saturated magnetization, coercivity and remnant magnetization. The atomic magnetic moment of manganese is greater than nickel ferrite. Substitution of manganese in the nickel ferrite increases the saturated magnetization whereas, coercivity decrease. Saturated Magnetization in the range of 55.4- 77.9emu/g. However, the composition with manganese content x=0.6 and nickel 1-x 0.4, coercivity of 106Oe shows nearly super paramagnetic behavior. Remnant magnetization also increase by substituting the manganese in the nickel ferrite.
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    Synthesis and Characterization of Ni metal/MnFe₂O₄ Nanocomposites
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2025) Hamza Farooq; CIIT/FA23-RPH-017/LHR; LHR TP 9848; Dr. Muhammad Yasir Rafique
    This thesis presents systematic research on nickel metal manganese ferrite nanocomposites (Ni-MnFe₂O₄) synthesized by the hydrothermal method at a temperature of 120 °C and a synthesis time of 20s hours. The optical and structural properties were investigated using X-ray Diffraction (XRD), Raman Spectroscopy, and the UVVisible spectroscopy method. In all prepared samples, ferrites phase corresponds to cubic spinel structure (space group Fd-3m) and Ni metals correspond to face centred cubic structure. Simultaneous existence of distinct and sharp peaks of Mn ferrite and Ni metal showed successfully synthesis of nanocomposite. The crystallite size, micro strain and lattice constant were determined for both phase (ferrite and metal) using XRD data. The average values of crystallite size, micro strain, and lattice constant for Manganese ferrite are approximately 27.3551 nm, 0.004174 ε and 8.48760 Å respectively. For nickel metal the average values of crystallite size, micro strain, and lattice constant are 29.69734 nm, 0.002683, and 3.5237 Å respectively. Five typical modes of spinel (A1g +Eg+3T2g) appeared in Raman spectra between 200 and 800 cm-1. The primary A1g mode at 640 cm-1 was blue-shifted by 7 cm-1 as the Ni content increased, indicating that the Fe-O bond covalency was increased at the octahedral sites. UV-Vis Photo spectroscopy was employed to determine the optical characteristic of prepared nanocomposites from UV-Vis spectroscopy analysis, direct bandgap of value 1.22 eV for Mn Ferrite sample and 1.10 eV for composites samples due to Ni₃d-O₂p charge transfers. The (Ni-MnFe₂O₄) composition exhibited distinct features, including a crystallite size and a maximum bandgap, indicating the relevance of strong quantum confinement. All this evidence demonstrates that the structural and optical properties can be controlled accurately through nickel substitution, making Ni- Mn ferrites interesting materials for application in photocatalytic and magneto-optical fields.