Yazar "Darwish, Moustafa A." seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim Yok
    Öğe
    Delving into the properties of nanostructured Mg ferrite and PEG composites: A comparative study on structure, electrical conductivity, and dielectric relaxation
    (Cell Press, 2023) El-Ghazzawy, Enas H.; Zakaly, Hesham M. H.; Alrowaily, Albandari W.; Saafan, Samia A.; Ene, Antoaneta; Abo-aita, Nagat M.; Darwish, Moustafa A.
    Magnesium ferrite (MgFe2O4) and polyethylene glycol (PEG) are materials known for their versatility in various applications. This study presents a comprehensive comparative analysis of the electrical conductivity and dielectric relaxation of nanostructured MgFe2O4 and its composites with PEG. Through experimentation, it was observed that incorporating PEG into MgFe2O4 did not lead to a high relative observed decrease or increase in electrical conductivity at room temperature. The study revealed that the composites maintained stable electrical behavior at room temperature, with a dielectric constant value of around 9 and a loss tangent value of around 0.1 at high frequency (around 7 MHz). The electron-hole hopping mechanism was identified as the underlying cause for the strong dielectric dispersion with frequency. The low dielectric loss and conductivity of the MgFe2O4 and PEG/ferrite composites make them promising candidates for high-frequency switching applications and microelectronic devices, particularly in scenarios where negligible eddy currents are essential. Additionally, complex impedance data analysis demonstrated that the capacitive and resistive properties of the composites are primarily attributed to grain boundary processes. This study provides a comprehensive analysis of the electrical and dielectric properties of MgFe2O4 and PEG composites and highlights their potential for many applications in materials science, particularly in electrical and electronic devices.
  • Küçük Resim
    Öğe
    Tailoring perovskite ceramics for improved structure, vibrational behaviors and radiation protection: The role of lanthanum in PbTiO3
    (Elsevier, 2024) Almousa, N.; Issa, Shams A. M.; Salem, M. M.; Darwish, Moustafa A.; Serag, Eman N.; Nazrin, S. N.; Zakaly, Hesham M. H.
    This study investigates the characteristics of lanthanum (La)-doped lead titanate (PbLaxTi(1-3x/4)O3 where, x = 0.0, 0.02, 0.04, 0.06, 0.08, and 0.1), a type of perovskite ceramic. It specifically focuses on analyzing its structure, vibrational properties, and efficacy in shielding against radiation. The prepared samples are investigated by X-ray diffraction (XRD), which clarified that the small doping of La (x <= 0.06) produced the required phase, and increasing the La doping (x > 0.06) produced nonrequired phases (secondary phase). Also, increasing the La doping converted the crystal symmetry from tetragonal to cubic, which was confirmed by the tetragonality raio (c/a) calculations. Also, the samples are investigated by Fourier transform infrared (FTIR) spectroscopy to confirm the XRD results. Transmission electron microscopy (TEM) examination clarified that the prepared samples were in the nanoscale range with a maximum crystallite size value of around 70 nm. In addition, the shielding effectiveness of all the prepared samples was theoretically evaluated using the Phy-X/PDS program by considering characteristics such as the linear attenuation coefficient (G(LAC)), mean free path (G(MFP)), transmission factor (TF), and radiation protection efficiency (RPE). Increasing the La concentration increases the theoretical density to 4.98 gm/cm3 at x = 0.1, leading to low TF and G(MFP) values and high G(LAC) values. This produces samples with high attenuation to radiation and high shielding effectiveness.