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    Electromagnetic shielding effectiveness of Ba(Zn1/3Nb2/3)O3: chopped strands composites for wide frequency applications
    (Korean Assoc Crystal Growth, Inc, 2023) Sahin, Ethem Ilhan
    In this work, the conventional mixed oxide process was used to form Ba(Zn1/3Nb2/3)O-3-chopped strands composites. The single phase compound with the chemical equation Ba(Zn1/3Nb2/3)O-3 was generated after sintering at 1250 degrees C for 4 h. Varied amounts of Ba(Zn1/3Nb2/3)O-3-chopped strands were fabricated for the structural examination. X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) were carried out for the structural analysis, and the results showed that the second phase did not form in Ba(Zn1/3Nb2/3)O-3. In addition to, the Ba(Zn1/3Nb2/3)O-3-strands composites were created by hot pressing using the compositions of Ba(Zn1/3Nb2/3)O-3-chopped strands in various rates and epoxy. The Ba(Zn1/3Nb2/3)O-3-chopped strands compound created in varied weights, and epoxy powder were utilized to manufacture microwave shielding effect composites. Using a two-port vector network analyser (VNA) device, the microwave shielding effect of Ba(Zn1/3Nb2/3)O-3-chopped strands composites was examined in a range of 0-8 GHz. A minimal of -44.75 dB shielding effectiveness value was reached at 6.24 GHz and 1.4 mm in thick. The Ba(Zn1/3Nb2/3)O-3-chopped strands were fabricated as composite and their properties were defined characterized for shielding effectiveness. To modify microwave shielding effectiveness, the content of components in the specimens may be adjusted for the wider and required frequency ranges.
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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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    Sustainable zeolitic tuff incorporating tea waste fired ceramic bricks: Development and investigation
    (Elsevier, 2023) Ibrahim, Jamal Eldin F. M.; Tihtih, Mohammed; Sahin, Ethem Ilhan; Basyooni, Mohamed A.; Kocserha, Istvan
    The present research examines the development of new porous ceramic bricks from Hungarian zeolitic tuff and tea waste as building materials. Recycling waste materials as a pore-forming agent in brick-making is a promising solution to environmental and economic challenges. Several zeolitic tuff/tea waste admixtures were milled in the planetary ball milling to produce homogenous powders. The substitution ratios were maintained as 0 %, 2 %, 4 %, 6 %, 8 %, 10 %, and 12 % by wt of zeolitic tuff. The ceramic disks were produced from the prepared mixtures via dry pressing and sintering at various temperatures (950-1250 degrees C) for consolidation. The produced bricks were investigated based on bulk density, apparent porosity, water absorption, volume shrinkage, thermal conductivity and compressive strength, as well as mineralogical, chemical, and morphological studies. The mineralogical determination confirms the existence of clinoptilolite, montmorillonite, cristobalite and illite as major phases in zeolite tuff. The experimental results reveal that the addition of tea waste produces hybrid bricks with better thermal insulation (0.17-0.504 W/m K), lighter weight (1.37-1.81 g/cm3), and lower compressive strength (5.52-34.4 MPa). However, the compressive strength value still lies within the range required by the standards. The production of burned bricks containing up to 10 wt% tea waste is viable without causing major changes in their technical characteristics. Developing new porous bricks using waste materials can help expand the application of sustainable and cost-effective insulation bricks in the construction industry.