Yazar "Demir, Ahmet" seçeneğine göre listele

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    Investigating ultra-thin rGO coated ZnO core-shell structures in MOS devices: electrical/dielectric characteristics and relaxation mechanism
    (Elsevier Ltd, 2024) Kırkbınar, Mine; İbrahimoğlu, Erhan; Demir, Ahmet; Çalışkan, Fatih
    The study focused on the relaxation and polarisation mechanisms of Al/(rGO:ZnO core-shell)/pSi/Al MOS structures. For this purpose, the rGO:ZnO core-shell structures were synthesised by sol-gel procedures and coated on pSi by spin-coating. The structures were characterized as chemical, morphological and micro-structural using FESEM-EDS, AFM, XRD and Raman analysis. Additionally, the capacitance (C), conductance (G/omega), dielectric permittivity (epsilon ' and epsilon ''), loss factor(tan delta), electric modulus(M ' and M '') of the samples were successfully examined by DS over the wide range of frequencies (100 Hz-1 MHz) for determining dielectric parameters. Three distinct regions were visible on the C-V and C-omega plots: accumulation (-4 to 0 V), depletion (0 to 2 V), and inversion (2 to 4 V). Two relaxation times (10(-4)s-10(-7)s) were obtained in epsilon '-V and epsilon '-omega graphs between 1-100 kHz (region 1) and 100 kHz-1 MHz (region 2). The relaxation times were according to the Maxwell-Wagner and dipolar polarisation mechanism. As a result, the capacitive effect was observed and the equivalent RC circuit obtained from the Cole-Cole diagrams allowed the samples to be used in energy storage or different electronic applications.
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    Öğe
    Multifunctional SnO2-@ doped glass fiber-reinforced concrete: improved microstructure, mechanical, dielectric, and energy storage characteristics
    (Elsevier Ltd, 2025) Ramazanoğlu, Doğu; Subaşı, Azime; Musatat, Ahmad Badreddin; Demir, Ahmet; Subaşı, Serkan; Maraşlı, Muhammed
    This study explores SnO₂-based hybrid composite (SnO₂-@) doped glass fiber-reinforced concrete (GFRC) for enhanced dielectric, energy storage, and mechanical performance. Microstructural analysis confirmed SnO₂-@ promotes ettringite and calcium silicate hydrate (C-S-H) formation, improving matrix integrity. Aged samples exhibited a 650 % increase in surface roughness (Ra) and over 200 % higher Leeb hardness, demonstrating durability. Dielectric spectroscopy revealed frequency-dependent tunability: 1 % SnO₂-@ achieved a peak dielectric constant (ε' = 130 at 10 kHz), shifting to ε' = 140 at 100 kHz for 2–3 % doping. AC conductivity surged by 60 %, correlating with SnO₂-@-induced interfacial polarization and charge mobility. Energy storage capacity improved significantly, attributed to optimized dipole alignment and reduced leakage currents. Color stability remained robust (ΔE* ≤ 2.8 post-aging), ensuring aesthetic viability. These results position SnO₂-@-doped GFRC as a multifunctional material for smart infrastructure, integrating structural resilience, adaptive dielectric properties, and energy storage potential for next-generation urban applications.