Yazar "Emek, Mehriban" seçeneğine göre listele

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    Öğe
    Elektromanyetik Ekranlama Uygulamaları İçin GdMnO3/PANI/Ba(Zn1/3Nb2/3)O3 Kompozitlerin Özellikleri
    (2023) Şahin, Ethem İlhan; Emek, Mehriban
    Bu çalışmada, oksitlerin karışımı tekniği kullanılarak GdMnO3-Ba(Zn1/3Nb2/3)O3 üretilmiştir. GdMnO3-Ba(Zn1/3Nb2/3)O3 kompozisyon bileşimleri yapısal analiz için çeşitli oranlarda oluşturulmuştur. Tek fazlı GdMnO3 ve Ba(Zn1/3Nb2/3)O3 bileşimi, 1200-1400°C arasında sinterlendikten sonra üretilmiştir. Yapısal analizi sonuçları, GdMnO3 ve Ba(Zn1/3Nb2/3)O3 ‘de ikinci fazın oluşmadığını göstermiştir. Yapısal analiz için X-ışını kırınımı (XRD) yapıldı. Ek olarak, GdMnO3/PANI/Ba(Zn1/3Nb2/3)O3 kompozitleri çeşitli miktarlarda GdMnO3-Ba(Zn1/3Nb2/3)O3 ve anilin bileşimleri kullanılarak sıcak presleme yöntemiyle üretilmiştir. (GdMnO3-Ba(Zn1/3Nb2/3)O3) ve anilin ağırlık oranları sırasıyla 1:1 idi. Çeşitli ağırlıklarda oluşturulan GdMnO3/PANI/Ba(Zn1/3Nb2/3)O3 bileşiği ve epoksi tozu kullanılarak mikrodalga kalkanlama etkili kompozitler üretilmiştir. Bir ağ analizör cihazı (NA) kullanılarak, GdMnO3/PANI/Ba(Zn1/3Nb2/3)O3 kompozitlerinin mikrodalga ekranlama etkisi 8-18 GHz aralığında incelenmiştir. 1.4 mm kalınlıkta 15.77 GHz'de minimum -56.77 dB ekranlama etkisi değeri elde edilmiştir. GdMnO3/PANI/Ba(Zn1/3Nb2/3)O3 kompozit malzeme olarak üretilmiş ve kalkanlama etkisi için özellikleri karakterize edilmiştir. Bu mikrodalga koruma performansı, daha geniş ve gerekli frekans bantları için örneklerdeki polianilin içeriği ve GdMnO3-Ba(Zn1/3Nb2/3)O3 içeriği kontrol edilerek kolayca ayarlanabilir.
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    Öğe
    ELEKTROMANYETİK KİRLİLİK ORTAMINDA KAOLİNİT/PVA KOMPOZİTLERİN ELEKTROMANYETİK KALKANLAMA ÖZELLİKLERİ
    (2023) Şahin, Ethem İlhan; Emek, Mehriban
    Bu çalışmada, kaolinit-PVA kompozitlerini oluşturmak için geleneksel oksitlerin karışımı yöntemi kullanılmıştır. Al2Si2O5(OH)4 kimyasal denklemine sahip tek fazlı kaolinit bileşiği, 1150°C'de 4 saat sinterlendikten sonra elde edildi. Yapısal araştırma için çeşitli miktarlarda kaolinit-PVA üretildi. Yapısal analiz için X-ışını kırınımı (XRD) yapıldı, bu da Al2Si2O5(OH)4'te ikincil fazın oluşmadığını gösterdi. Ayrıca çeşitli oranlarda Al2Si2O5(OH)4-PVA bileşimleri ve epoksi tozu kullanılarak mikrodalga kalkanlama etkili kompozitler sıcak presleme yöntemiyle üretilmiştir. Bir ağ analizör cihazı kullanılarak, Al2Si2O5(OH)4/PVA kompozitlerinin mikrodalga ekranlama etkisi 6-18 GHz aralığında incelenmiştir. 1.4 mm kalınlıkta 6.92 GHz'de minimum -47.02 dB ekranlama etkisi değeri elde edilmiştir. Al2Si2O5(OH)4/PVA bileşikleri kompozit malzeme olarak üretilmiş ve kalkanlama etkisi için özellikleri karakterize edilmiştir. Daha yüksek ve gerekli frekans bantlarında çalışmak için, kompozitlerdeki bileşenlerin miktarı ayarlanarak, mikrodalga kalkanlama etkisi performansı değiştirilebilir.
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    Nickel Doping Effects on the Structural and Dielectric Properties of Ba(Zn1/3Nb2/3)O3 Perovskite Ceramics
    (Springer, 2021) Qasrawi, A.F.; Sahin, Ethem İlhan; Emek, Mehriban
    The effects of nickel doping into Ba(Zn1/3Nb2/3)O3 (acronym: BZN) ceramics is structurally, morphologically and electrically investigated. The nickel substitution in sites of Zn which was carried out by the solid state reaction technique strongly enhanced the structural, morphological and electrical performances of the BZN. Specifically, while the lattice constant and crystallite sizes increased, the microstrain and the defect density decreased. The relative density of the BZN ceramics increased from 95.40% to 98.24% upon doping of Ni with content of x = 0.05. In addition, the Ni doping increased the values of electrical conductivity without significant changes in the dielectric constant values. It is also observed that the doping the BZN ceramics highly altered the temperature dependent variation of the relative dielectric constant. In the temperature range of 293–473 K, the x = 0.05 Ni doped BZN samples were less sensitive to temperature. The dynamics of the temperature dependent dielectric response is dominated by the coupled defects excitation mechanisms. Both of the temperatures and frequency dependent dielectric constant, dielectric loss and electrical conductivity suggests that the Ni doped Ba(Zn1/3Nb2/3)O3 ceramics is more appropriate for electronic device fabrication than the pure ones. © 2021, The Minerals, Metals & Materials Society.
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    Production and microwave electromagnetic shielding effectiveness of polyaniline-La2Ti2O7:Er,Yb composites
    (Korean Assoc Crystal Growth, Inc, 2021) Sahin, Ethem Ilhan; Canturk, Selim Burak; Emek, Mehriban; Genc, Seval; Kartal, Mesut
    In this research, La2Ti2O7 doped with erbium-ytterbium was produced by using solid state technique. A series of compounds with the chemical equation (La1-x-yREx-y)(2)Ti2O7 were doped with (Er3+, x = 0.025, 0.050) and (Yb3+ y = 0.02) rare earth ions prepared by conventional solid state reaction method at 1350 degrees C for 24 h. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were carried out for the structural analysis, which showed that second phase did not form in (La1-x-yREx-y)(2)Ti2O7. Additionally, the polyaniline- erbium, ytterbium doped La2Ti2O7 composites were fabricated via hot pressing using the compositions of (La0.955Yb0.02Er0.025)(2)Ti2O7, (La0.93Yb0.02Er0.05)(2)Ti2O7 and aniline. The weight ratios of erbium-ytterbium doped lanthanum titanate and aniline were 1:1 and 1:3 respectively, and epoxy resin was utilized to develop microwave shielding effectiveness composites. The microwave shielding effectiveness performances of polyaniline- La2Ti2O7: erbium-ytterbium composites were examined by shielding effect in 0-8 GHz using two-port vector network analyzer. A minimum of - 34.37 dB shielding effect performance was obtained in 6.27 GHz at the thickness of 2.0 mm. This shielding effect performance can be adjusted easily by managing the content of polyaniline in the composites for the needed frequency bands.
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    Shielding effectiveness performance of polyaniline-NiFe2O4:Cu composites for sub-8 GHz applications
    (Springer, 2023) Sahin, Ethem Ilhan; Emek, Mehriban; Ibrahim, Jamal Eldin F. M.; Yumusak, Goerkem; Kartal, Mesut
    Herein, NiFe2O4 doped Cu was synthesized using a mixed-oxide method to investigate its potential for creating composites with high microwave shielding effectiveness. The compound NiFe2-xCuxO4 was synthesized with x values of 0.1, 0.3 and 0.5, respectively. After sintering at 1250 degrees C for 4 h, single-phase Ni ferrite was formed. To analyze the phase composition and the structure of the synthesized compound, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were employed. The study's findings showed that NiFe2-xCuxO4 did not exhibit a second phase. To create composites with high microwave shielding effectiveness, polyaniline-NiFe2O4:Cu composites were fabricated using a hot-pressing technique, with compositions of NiFe1.9Cu0.1O3.95, NiFe1.7Cu0.3O3.85 and NiFe1.5Cu0.5O3.75 with the aniline, The weight ratios of Cu-added nickel ferrite and aniline were changed from 1:1 to 1:3, and epoxy resin was used. Using a two-port vector network analyzer, the polyaniline-NiFe2O4:Cu composites' microwave shielding effectiveness performance was examined in the range between 0 and 8 GHz. The study found that the shielding effect of the composites could be easily modified by changing the amount of polyaniline present in the specimens for the appropriate frequency bands. At 6.82 GHz, using a sample with a thickness of 2.0 mm, a minimum shielding effect performance of - 29.74 dB was achieved. Overall, the results of this study demonstrate the potential of polyaniline-NiFe2O4:Cu composites as effective microwave shielding materials.
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    Shielding effectiveness performance of polyaniline-NiFe2O4:Cu composites for sub-8 GHz applications (vol 55, 500, 2023)
    (Springer, 2023) Sahin, Ethem Ilhan; Emek, Mehriban; Ibrahim, Jamal Eldin F. M.; Yumusak, Goerkem; Kartal, Mesut
    [Abstract Not Available]
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    Structural and shielding effectiveness properties of (NiFe2O4/chopped strands) composites for 6.5-18 GHz applications
    (Springer, 2024) Sahin, Ethem Ilhan; Ibrahim, Jamal-Eldin F. M.; Emek, Mehriban; Sinsoysal, Bahaddin; Amanzholova, Alina
    In this research, a mixed oxide technique was employed to create composite materials comprising NiFe2O4-chopped strands, aimed at evaluating their structural properties and microwave shielding effectiveness. The composites, produced through a hot-pressing process with varying proportions of NiFe2O4 and chopped strands, were integrated with epoxy to enhance their shielding capabilities. X-ray diffraction confirmed the formation of single-phase NiFe2O4, free from secondary phases. Scanning electron microscopy analysis corroborated the presence of cubic crystalline NiFe2O4, without microstructural impurities. The microwave shielding performance of the composites was assessed within the 6.5-18 GHz frequency range using a network analyzer (NA), revealing a minimum shielding effectiveness of - 36.34 dB at 16.56 GHz for a 1.3 mm thick sample. These findings demonstrate the successful fabrication of NiFe2O4-chopped strands composites with tunable microwave shielding properties, achieved by adjusting the NiFe2O4 content, allowing for tailored performance across various frequency bands.
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    Structural and shielding effectiveness properties of (NiFe2O4/chopped strands) composites for 6.5-18 GHz applications (vol 35, 1407, 2024)
    (Springer, 2024) Sahin, Ethem Ilhan; Ibrahim, Jamal-Eldin F. M.; Emek, Mehriban; Sinsoysal, Bahaddin; Amanzholova, Alina
    [Abstract Not Available]
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    Theoretical Investigation of Heat Capacities as a Function Temperature of Stannous Selenide (SnSe) Using Einstein-Debye Approximation
    (2023) Emek, Mehriban; Şahin, Ethem İlhan
    A new alternative approach has been suggested for evaluating the heat capacities of stannous selenide (SnSe), based on the Einstein-Debye approximation. It is well known the thermal behavior of solids is a very important theoretical problem that has been explored thoroughly with the development of Einstein, Debye and recently developed Einstein-Debye approximations. Many additional thermophysical characteristics of materials may be analyzed using the Einstein-Debye approach employed in this study. As an application, the heat capacities have been computed by using the Einstein-Debye method for SnSe in the temperatures range between 40 and 900 K. The temperature dependence of heat capacities have been computed and found to be in good accord with the literature throughout a wide temperature range.