Browsing by Author "Karaaslan, Muharrem"

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Citation - WoS: 1
Citation - Scopus: 2
Investigation of Structural, Magnetic and Microwave Absorption Properties of Nixco1-xfe2o4/Ni:zno (x:0.0, 0.5, and 1.0) Embedded Epoxy Composites
(Springer Heidelberg, 2022) Kıvrak, Burak; Tümen, Kutluhan Utku; Karaaslan, Muharrem; Akyol, Mustafa
In this study, NixCo1-xFe2O4/Ni:ZnO (x:0.0, 0.5, and 1.0) epoxy-based composite structures were manufactured by sol-gel method. The structural, morphological and magnetic characteristics were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). Electromagnetic wave (EMW) absorption measurements were carried out using a vector network analyzer (VNA) between 8 and 12 GHz (X band). Ni substitution with Co decreases the crystallite size, average particle size, magnetic saturation (M-s) and the coercive field (H-c) values of cobalt-ferrite spinel structure. EMW characterization results showed that minimum reflection loss (RL) - 30.91 dB (99.9% absorption) at 10.76 GHz, and the maximum bandwidth of 1.81 GHz were observed for the RAM1 composite. In addition, the substitution of Ni2+ into the cobalt-ferrite structure resulted in the shifting absorption peaks to the higher frequency region (towards K-u band).
Citation - WoS: 9
Citation - Scopus: 11
Pani-Coated Yig/Cfo Hybrid Composites as Advanced Electromagnetic Wave Absorber Through X-Band
(Elsevier Science Sa, 2023) Kıvrak, Burak; Sergun, Atalay; Karaaslan, Muharrem; Akyol, Mustafa
Polyaniline (PANI)-coated Y3Fe5O12(YIG)/CoFe2O4(CFO) hybrid composites were synthesized via sol-gel and oxidative polymerization methods to achieve advanced microwave absorption properties. The structural, morphological, magnetic, and microwave absorption characteristics of the resulting samples were analyzed by performing X-ray diffraction (XRD), scanning electron microscopy (SEM), vibration sample magnet-ometer (VSM), and vector network analyzer (VNA). XRD results revealed that CFO and YIG have cubic crystal structures with Fd3m and Ia3d space symmetry, respectively, with an average crystallite size of 35.3 nm and 42.9 nm. The Ferro/ferrimagnetic signals were detected from the ferrite samples' room temperature magnetic hysteresis loops. The incorporation of PANI and YIG into the composites resulted in a decrease in their magnetic saturation (Ms) and coercive field (Hc) values. VNA measurements demonstrated that nearly all samples achieved 90% absorption (& LE;-10 dB) of incident electromagnetic waves throughout the X-band frequency range. The minimum reflection loss (RLmin) value reaches - 47.34 dB at 8.14 GHz, with an effective bandwidth of 4.00 GHz, covering the entire X-band and beyond. These impressive absorption characteristics suggest that the manufactured composites possess potential as viable candidates for defense applications conducted at X-band frequency.& COPY; 2023 Elsevier B.V. All rights reserved.
Citation - WoS: 10
Citation - Scopus: 11
Phase (1t/2h) Dependent Electromagnetic Wave Absorbing Performance of Flower-Like Mos2 Nanosheets
(Elsevier, 2023) Aka, Cemal; Kıvrak, Burak; Teksen, Fikret Alpay; Akyıldız, Hasan; Akgöl, Oğuzhan; 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.
Citation - WoS: 2
Citation - Scopus: 4
Polyaniline-Functionalized Nanosized Cobalt Ferrite-Decorated Mos2 Composites for Broadband Electromagnetic Wave Absorption
(Amer Chemical Soc, 2024) Kivrak, Burak; Akyildiz, Hasan; Akgol, Oguzhan; Karaaslan, Muharrem; Akyol, Mustafa
This study presents the synthesis of polyaniline (PANI)-coated cobalt ferrite-decorated molybdenum disulfide (MoS2@CoFe2O4); a composite architecture engineered to combine unique morphological, magnetic, and dielectric properties for the electromagnetic wave/radar absorption applications. MoS2 and CoFe2O4 were produced separately using a one-step hydrothermal process. Then, the CoFe2O4 nanoparticles were integrated into the flower-like MoS2 nanosheets using the sonication method. Finally, PANI was synthesized through in situ polymerization of aniline on the surface of MoS2@CoFe2O4 to create the final design as well as to boost the dielectric performance. Structural analysis confirmed the existence of the 2H phase and a minor trace of the 1T phase in MoS2, while CoFe2O4 displayed a cubic structure without any detectable impurities. Scanning electron microscopy verified the successful distribution of CoFe2O4 particles within the MoS2 nanosheets, aligning with the design's intended configuration. The electromagnetic wave (EMW) characteristics of the composites were analyzed by using a vector network analyzer. The MoS2@CoFe2O4 demonstrated a broad effective absorption bandwidth, spanning from the X-band to the Ku-band with a minimum matching thickness of just 2 mm. The reflection loss minimum value (RLmin) reached -22.82 dB at 8.96 GHz, corresponding to a 99.47% absorption of the incident EMWs. The addition of PANI at 50% by weight further increased the RLmin value to approximately 99.999% absorption (-50 dB), indicating enhanced impedance matching and absorption efficiency.
Citation - WoS: 13
Citation - Scopus: 15
Synthesis and Characterization of Nanoparticles Reinforced Epoxy Based Advanced Radar Absorbing Composites
(SPRINGER, 2021) Tümen, Kutluhan Utku; Kıvrak, Burak; Alkurt, Fatih Ozkan; Akyol, Mustafa; Karaaslan, Muharrem; Ekicibil, Ahmet
In this study, the structural and magnetic properties of NixCo1-xFe2O4 (0.0 <= x <= 1.0) and ZnO nanoparticles synthesized by the sol-gel method were investigated. The microwave property of the composite structures produced from the combination of ZnO and NixCo1-xFe2O4 nanoparticles dispersed in the epoxy matrix property was studied in the X-band frequency range. The crystal structures of NixCo1-xFe2O4 have not been disrupted by Ni substitution, however, the lattice parameters of samples decrease due to the smaller ionic radii of Ni+2 compared to Co+2 ions. The magnetic saturation (M-s) and remanence magnetization (M-r) decreased with an increasing amount of Ni in NixCo1-xFe2O4 structure. According to the microwave absorption properties of samples, the maximum reflection loss (RL) value was found as -28.10 dB at 10.23 GHz frequency in RAC(4) sample. On the other hand, maximum bandwidth was found at 2.95 GHz around -10 dB for RAC5 sample. All composites exhibit efficient RL in the X-band indicating that they can be used in potential applications in aviation, radar, and defense vehicles.