A. Tawfik

Bio: A. Tawfik is an academic researcher from Tanta University. The author has contributed to research in topics: Ferrite (magnet) & Coercivity. The author has an hindex of 7, co-authored 9 publications receiving 158 citations.

Simulation of Wasp-Waisted Magnetic Hysteresis Loop for NiCoP-Coated BaFe12O19–Polystyrene Bilayer Composite Film

Abstract: Brillouin function was modified to model the wasp-waisted magnetic hysteresis loop for soft-magnetic NiCoP-coated hard-magnetic M-type ferrite BaFe12O19 polystyrene (PS) bilayer composite film taking into account the effective applied magnetic field due to localized impurity phases and significant change in the azimuthal angle of the magnetic moment due to the formation of bilayer structure of film by the addition of PS. It is shown that there is a good fit to the experimental data observed in wasp-waisted magnetic hysteresis loop. The analysis shows that the forward magnetization and reversal process are typical.

Infrared and structural studies of Mg1–xZnxFe2O4 ferrites

Abstract: Compositions of polycrystalline Mg–Zn mixed ferrites with the general formula Mg1−xZnxFe2O4 (0≤x≤1) were prepared by the standard double sintering ceramic method. The structural properties of these ferrites have been investigated using X-ray diffraction and infrared absorption spectroscopy. The lattice parameter, particle size, bonds length, force constants, density, porosity, shrinkage and cation distribution of these samples have been estimated and compared with those predicted theoretically. Most of these values were found to increase with increasing Zn content. The energy dispersive (EDS) analysis confirmed the proposed sample composition. The scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs showed aggregates of stacked crystallites of about 200–800 nm in diameter. Far infrared absorption spectra showed two significant absorption bands. The wave number of the first band, ν1, decreases with increasing Zn content, while the band, ν2 shifts linearly towards higher wave numbers with Zn contents, over the whole composition range. The room temperature electrical resistivity was found to decrease as Zn-content increases. Values of the vacancy model parameters showed that the packing factors Pa and Pb decrease, the fulfillment coefficient, α, remains almost constant and the vacancy parameter, β, strongly increases with increasing Zn content in the sample. The small values of Pa, Pb, α and the strong increase of the vacancy parameter, β, indicate the presence of cation or anion vacancies and the partial participation of the Zn2+ vacancies in the improvement of the electrical conductivity in the Mg–Zn ferrites.

Review on Magnetocaloric Effect and Materials

Abstract: A detailed discussion of magnetocaloric properties of distinct materials is a vital aspect in magnetic refrigeration technology. This review paper deals with all kinds of magnetocaloric materials such as ferromagnetic perovskites, glass ceramics, oxide-based composites and spinel ferrites. The comparative study of magnetocaloric properties revealed that manganites have the potential applications in magnetorefrigeration technology.