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    Öğe
    Absorbing the entire X-band via conductive polymer polyaniline coated Y3Fe5O12/NiFe2O4 hybrid composites
    (Springer, 2023) Akyol, Mustafa; Aka, Cemal; Inozu, Onat; Alkurt, Fatih Ozkan; Karaaslan, Muharrem
    Conductive polymer coated Y3Fe5O12 (YIG)/NiFe2O4 (NFO) hybrid radar absorbing composites were studied in this work. The magnetic YIG and NFO particles were synthesized by sol-gel method, and then covered with a conductive PANI polymer by in-situ polymerization technique. The structural and magnetic properties of produced particles and hybrid composites were studied by XRD, SEM and VSM measurements. The microwave property of the hybrid composites reinforced in the epoxy matrix was studied in the X-band frequency range. The electromagnetic wave absorbing bandwidth in the X-band increases with the content of YIG in the hybrid composites. A broadband radar absorbing has been observed in EPYN08 and EPYN10 hybrid composites having entire X-band with an absorption criterion of - 10 dB. The maximum reflection loss (RL) value was found as - 35.1 dB at 10.8 GHz frequency in EPYN06 sample. The nanocomposite structures formed by combining magnetic and dielectric materials show better electromagnetic wave absorption properties rather than the each components in the composites. Hence, the experimental results of hybrid composites may be a promising candidate for radar and defense vehicles due to their fully absorbing property in the X-band.
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    Öğe
    Broadband electromagnetic wave absorbing via PANI coated Fe3O4 decorated MoS2 hybrid nanocomposite
    (Elsevier Science Sa, 2023) Aka, Cemal; Akgol, Oguzhan; Karaaslan, Muharrem; Akyol, Mustafa
    High performance electromagnetic wave (EMW) absorbing material systems are required for stealth applications and sensitive electronic devices. Absorbing of an incident EMW in a wide band range still has limitations in terms of materials system and engineering. It is required to extend the bandwidth and minimize the reflection from the material system for the next level stealth technologies. In this work, hybrid nanocomposite structures are developed by semiconductor flower-like MoS2 nanosheets, Fe3O4 magnetic nanoparticles and conductive poly aniline. A systematic study is presented by investigation the structural, magnetic, morphological, thermal, electronic and electromagnetic characteristic of hybrid nanocomposites (Fe3O4:MoS2, PANI@Fe3O4, PANI@MoS2 and PANI@Fe3O4:MoS2). EMW absorption characteristics results showed that Fe3O4:MoS2 and PANI@Fe3O4:MoS2 hybrid nanocomposites exhibit excellent EMW absorption characteristics. While the minimum reflection loss (RL) value was found as 54.97 dB at 15.99 GHz for the Fe3O4:MoS2 nanocomposite, the broad bandwidth (7.65 GHz) was observed in PANI@Fe3O4:MoS2 hybrid nanocomposite having 39.96 dB RL. According to the experimental results, a lightweight and high temperature resistance PANI@Fe3O4:MoS2 like hybrid nanocomposite can absorb almost 90% of incident EMW in a wide bandwidth.
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    Öğe
    Effect of Synthesizing Process on the Formation of Fe3O4 Magnetic Nanoparticles
    (2023) Aka, Cemal; Akyol, Mustafa
    In this work, the effect of synthesizing process on the morphology, structure, and magnetic properties of Fe3O4 magnetic nanoparticles have been studied by performing X-ray diffraction, scanning electronic microscopy, and vibrating sample magnetometer measurements. Fe3O4 nanoparticles were synthesized by hydrothermal and solvothermal methods. X-ray diffraction analysis revealed that both samples have cubic crystal phase. However, Fe2O3 impurity peaks were observed in the sample synthesized by hydrothermal method. The crystallite sizes of samples synthesized by hydrothermal and solvothermal methods were approximately 38 and 24 nm, respectively. The scanning electron microscope images show that spherical porous and cubic shape Fe3O4 nanoparticles were obtained by solvothermal and hydrothermal method, respectively. The average particle sizes of Fe3O4 samples synthesized by hydrothermal and solvothermal methods were determined as 220 and 450 nm, respectively. Both samples behave a soft ferromagnetic characteristic having almost zero coercive field. The magnetic saturation values of Fe3O4 nanoparticles synthesized by hydrothermal and solvothermal methods were determined as 28.78 and 77.31 emu/g, respectively. As a result of the characterizations, porous Fe3O4 nanoparticles synthesized by solvothermal method show better crystal structure, morphological and magnetic properties than Fe3O4 nanoparticles synthesized by hydrothermal method.
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    Öğe
    Phase (1T/2H) dependent electromagnetic wave absorbing performance of flower-like MoS2 nanosheets
    (Elsevier, 2023) Aka, Cemal; Kivrak, Burak; Teksen, Fikret Alpay; Akyildiz, Hasan; Akgol, Oguzhan; Karaaslan, Muharrem; Akyol, Mustafa
    A study was carried out to determine the phase-dependent electromagnetic wave (EMW) absorption performance of MoS2 particles via systematically diversified hydrothermal synthesis conditions such as time, temperature, precursor molarity, and oxalic acid concentration. The formation of mixed-phase structure was verified depending on the presence of the characteristic diffraction peaks belong to 1T (trigonal, P3?m1 space group) and 2H (hexagonal, P63/mmc space group) phases in the X-ray diffraction (XRD) patterns. Phase-pure 2H-MoS2 was obtained at 200 degrees C after 12 h of reaction and using 5 mmol oxalic acid. Microscopic examinations indicate that MoS2 particles formed by assembling several nanosheets to create a flower-like morphology. The size, shape, and the distance between the nanosheets were observed to change with increasing temperature, time, and acid concentration. The band gap was found to be modified depending on the phase distribution and decreased from 1.54 eV (2H) to a minimum of 0.64 eV (1T/2H) with the formation of the 1T (metallic) phase. Finally, the minimum reflection loss was measured as -67.73 dB (99.9999 % of absorption at 9.05 GHz) with an effective absorption bandwidth (EAB) of 3.52 GHz for the sample composed of 1T/2H mixed-phased structure.
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    Öğe
    Synthesis and characterization of some physical properties of Fe3O4 doped MoS2/PANI hybrid composites
    (Adana Alparslan Türkeş Bilim ve Teknoloji Üniversitesi, 2024) Aka, Cemal; Akyol, Mustafa
    Malzemelerde elektromanyetik dalgaları absorbe eden sistemler, gizli uygulamalar ve hassas elektronik ekipmanlar için gereklidir. Bununla birlikte, EMW'yi geniş bir bant genişliği boyunca absorbe etme yeteneği, malzeme sistemleri ve mühendisliğindeki bazı sınırlamalarla hala sınırlıdır. Bant genişliğinin artırılması ve malzeme sistemi yansımalarının azaltılması, gelecekteki gizli teknolojilerin geliştirilmesi için çok önemli ilerlemelerdir. Bu çalışmada, yarı iletken MoS2 nano tabakaları, Fe3O4 manyetik nanopartiküller ve iletken polianilin kullanılarak hibrit yapılar geliştirilmiştir. Bu hibrit yapıların yapısal, manyetik, morfolojik, termal, elektronik ve elektromanyetik özelliklerini incelemek için sistematik bir yaklaşım kullanılmıştır. Analiz sonucunda, elektromanyetik dalgaları etkili bir şekilde absorbe edebilen Fe3O4:MoS2 ve PANI@Fe3O4:MoS2 hibrit yapılarının üstün EMW absorpsiyon özelliklerine sahip olduğu görülmüştür. Özellikle, F10M90 numunesi 3 mm kalınlıkta ve 7,86 GHz frekansta -54,97 dB'lik minimum yansıma kaybına ulaşmış ve 4,0 GHz'lik etkili bir soğurma aralığına sahip olmuştur. P50F2.5M47.5 numunesi 2 mm kalınlıkta ve 13,18 GHz frekansta -27,58 dB'lik minimum yansıma kaybına ulaşmış ve 8,03 GHz'lik etkili bir soğurma bant genişliğine sahip olmuştur. Deneysel bulgulara dayanarak, hafif yapıları ve yüksek sıcaklık kararlılıkları ile karakterize edilen PANI@Fe3O4:MoS2 gibi hibrit nanokompozitlerin geniş bant aralığında EMW'nin neredeyse %99'unu etkili bir şekilde absorbe edebildiği sonucuna varılmıştır.