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    Fabrication and Electromagnetic Absorbing Properties of Hexagonal Ferrites
    (2021) Bayrakdar, Harun
    Nanocomposite materials were obtained by synthesizing $Ba_2Bi_2Co_2Fe_{12O}_{22}$ Nano Particles with polyaniline and polyacrylonitrile polymers. Composites in this nanostructure; structural, magnetic and electromagnetic absorption properties were examined. It was observed from the x-ray analysis that the nano-structured particles had crystalline structure and shown Y-type hexagonal structure. It can be also seen from the IR measurements that it has this structure at 878 and 650 $cm^{?1}$. The Electron Spin Resonance experiment of nanoparticles have been measured at room temperature and shown quite wide spectra and splitting factor. Vibration Sample Magnetometer measurements were made at 10-50 and room temperature. It can be said that nanoparticles useable so successful the magnetic recording media, applications of microwave technologies. Electromagnetic absorption experiments were measured approximately 5-20 GHz in the frequency band by used the free space method. These electromagnetic absorbers are using for 1,5 mm. thickness of the samples obtained 6 GHz. wide - 50 db. loss of reflection was measured.
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    Microwave-Assisted Hydrothermal Synthesis of Nanosheet Layered Hexagonal Spinel Ferrites for Efficient Electromagnetic Wave Absorbing
    (Amer Chemical Soc, 2024) Bayrakdar, Harun
    A microwave-induced combustion method has been utilized to prepare nanosized powders of hexagonal spinel ferrites using urea and glycine as fuel. The structural and electromagnetic absorption of these products was investigated using X-ray diffraction (XRD). From the (3,1,1) and (1013) peaks in XRD measurements, it was seen that the samples we synthesized were nanosized spinel and y-phase hexagonal ferrite. In addition, Fourier-transform infrared measurements showed that the synthesized samples had high absorption values showing Fe-O, which is between 878 to 4000 cm(-1), and metal-oxygen transitions, which are between the 700 and 2500-3000 cm(-1) in the spinel and hexagonal phases. From the scanning electron microscope image of the particles, it is seen that they are homogeneous, filled structures with similar to 35-40 nm. It appears from vector network analyzer measurements that the synthesized 1.5 mm thick composite materials have very high electromagnetic absorption properties and that these composites can also be used in electromagnetic interference, Wi-Fi applications, and health.
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    Synthesis and investigation of small g-values for smart spinel ferrite nanoparticles
    (Elsevier Science Sa, 2021) Bayrakdar, Harun; Yalcin, Orhan; Ozum, Songul; Cengiz, Ugur
    Smart spinel and hexagonal ferrite nanoparticles (NPs) have been fabricated by ethylenediaminetetraacetic acid (EDTA) and cetyltrimethylammonium bromide (CTAB) assisted hydrothermal route by using NaOH solution. Electron spin resonance (ESR) measurements of the spinel and hexagonal ferrite NPs have been performed by a high sensitive conventional x.band (similar to 9.5-9.8 GHz) spectrometer at room temperature (RT). The measured five small g-values by ESR spectra at RT may be relevant for quantum information processing. Quantum computing and relativistic quantum computing by two-level system (qubit) have been realized by spinel type NPs at RT. Temperature evolution of magnetic hysteresis loops, magnetization, coercivity (H-C), saturation field (H-S), saturation magnetization (M-S) and remanent magnetization (M-r) have been investigated. (C) 2021 Elsevier B.V. All rights reserved.