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228 results on '"Hemeda, O. M."'

40. Structural and Magnetic Properties of Zinc and Silicon Oxides Doped Cu Ferrite for Temperature Controller Devices

Author

Hessien M. M., Ahmed E. M., and Hemeda O. M.

Subjects
copper ferrite, temperature controlling, doping, magnetic properties, curie temperature, 75.50y, 75.60ej, 75.85+q, Technology, Chemical technology, TP1-1185, Chemicals: Manufacture, use, etc., TP200-248
Abstract

The effects of Si+4 and Zn+2 substitutions on the structural and magnetic properties of Cu1−xZnx+ySiyFe2−2yO4 ferrites prepared by double sintering ceramic technique have been investigated. From X-ray diffraction analysis, it was found that substitution of Zn and Si enhanced sintering process and crystallization. The XRD peaks increase by increasing Zn and Si content. On the other hand, the initial permeability decreases sharply at Curie temperature for all samples, which makes Zn/Si co-doped CuFe2O4 spinel ferrites a very promising candidate for magnetic switches, magnetic temperature transducers (MTT), and for fabrication of temperature sensitive controller devices. The important change of Curie temperature of CuFe2O4 compound occurs by simply controlling the content of Zn and Si within CuFe2O4 and results in obtaining magnetic materials with desired Curie temperature. Magnetic hysteresis loop measurements show that the samples have soft magnetic character.

Published
2015
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45. The Impact of La Substitution on the Structural, Molecular, Morphological, and Thermal Properties of Mn0.6Zn0.4Fe2O4.

Author

Mostafa, M., Khalaf, A., El-Maghraby, E. M., Dagher, R. A., and Hemeda, O. M.

Subjects
THERMAL properties, X-ray diffraction, MAGNETIC ions, MAGNETIC permeability, TRANSMISSION electron microscopy
Abstract

The current work involves the use of flash auto combustion procedure to synthesize nano-ferrites Mn0.6Zn0.4LaxFe2-xO4, (x = 0.00, 0.02, 0.04, 0.06, 0.08, and 0.10) annealing at 500 °C for 4 h. X-ray Diffraction (XRD), Fourier transition infrared spectroscopy (FTIR), and high-resolution transmission electron microscopy (HRTEM) were used to characterize the structural properties of produced samples. Scanning electron microscopy (SEM) was utilized to examine the surface morphology of the samples at various Lanthanum concentrations. From XRD, the spinel cubic structure for all samples with few traces of secondary phase at high La concentrations is assured. The crystallite size is estimated to be in the nanoscale range of 13.16–18.13 nm using the Debye–Scherrer formula. The appearance of characteristic vibrational bands near 460 cm−1 and 563 cm−1, which correspond to the octahedral and tetrahedral sites, respectively, confirms the formation of the spinel structure. SEM micrographs show that the grains are nearly irregular in shape, and the accumulation of La+3 ions at the grain boundaries exerts tensile strength and pressure on the grain itself, reducing the grain size. The particle size estimated by TEM coincides well with the crystallite size determined by XRD. The thermogravimetric analysis, (TGA), was used to investigate the thermal properties of the nanoferrites from room temperature to 1000 °C. In comparison to the other samples, the sample with x = 0.04 has greater thermal stability and the TEM measurement indicates that this sample has the smallest particle size. Therefore, we can assert that the thermal stability improves as the particle size decreases. The magnetic permeability was measured in the temperature range 303–773 K at a fixed frequency of 10 kHz and at various La contents. The sample with x = 0.04 has a minimal permeability value, showing that the separation brought on by La ions has diminished the super exchange contact between magnetic ions. [ABSTRACT FROM AUTHOR]

Published
2023
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