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    A novel lanthanum hexaboride-modified cementitious composites: evolution and microstructural architecture of LaB6-integrated GFRC systems with enhanced dielectric response
    (Elsevier Ltd, 2026) Demir, Ahmet; Subaşı, Serkan; Dehgan, Haydar; Ramazanoğlu, Doğu; Maraşlı, Muhammed; Aksu, Mecit; Gencel, Osman; Musatat, Ahmad Badreddin; Subaşı, Azime
    This study investigates the integration of lanthanum hexaboride (LaB6) microparticles into glass fiber-reinforced concrete (GFRC) to improve its dielectric and microstructural properties. GFRC mixtures with 1–3 % LaB6 replacement were characterized for capacitance, impedance, dielectric constant (ε′ and ε″), dissipation factor (tanδ), electrical modulus (M′ and M″), and Cole-Cole diagrams across varying frequencies (20 Hz–5 MHz) and hydration times (7–58 days). Comprehensive Microstructural, Thermal Stability, and Chemical Characterization analyses were also performed. Results demonstrate that LaB6 significantly improves GFRC's capacitance, conductivity, and dielectric properties. Specifically, L2 and L3 samples exhibited capacitance values approximately 100 times higher than the reference and L1 samples after 56 days, and approximately 25 times greater capacitance behavior across the tested frequency spectrum. The real dielectric constant (ε′) reached 250-fold, decreasing by about 10 times with LaB6 addition in L2 and L3, indicating improved insulation. Dielectric losses (ε″) were also markedly higher for L2 and L3, approaching 100 times greater than R and L1, implying favorable conductive functionality. Cole-Cole analysis indicated minimal dielectric dispersion for L2 and L3, suggesting near-ideal polarizable interfaces. Equivalent circuits were fitted, demonstrating that LaB6 significantly influences the electrical transport and storage mechanisms within the GFRC composites, leading to improved dielectric performance. Scanning electron microscopy (SEM) revealed denser microstructures, while thermogravimetric analysis (TGA), differential thermal analysis (DTA), and Fourier-transform infrared spectroscopy (FTIR) corroborated enhanced thermal stability, bond strength, and favorable microstructural interactions. These findings highlight LaB6 as a promising additive for developing high-performance cementitious composites with tailored electrical responses for smart concrete applications.
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    Multifunctional GFRC composites: PEDOT: PSS-driven dielectric enhancement for energy storage and sensing applications
    (Elsevier Ltd, 2026) Demir, Ahmet; Musatat, Ahmad Badreddin; Subaşı, Azime; Ramazanoğlu, Doğu; Dehgan, Haydar; Maraşlı, Muhammed; Gencel, Osman; Subaşı, Serkan
    This study presents a comprehensive investigation into the development and characterization of multifunctional Glass Fiber Reinforced Cement (GFRC) composites enhanced with Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT: PSS) to impart advanced electrical properties. We systematically analyzed the influence of PEDOT: PSS concentration (0–15 wt %) and curing age on the dielectric behavior of these novel composites, evaluating their capacitance, dielectric constant, loss factor, and electrical modulus across a broad frequency range (10 Hz-10 MHz). The integration of PEDOT: PSS significantly modified the material's electrical characteristics, demonstrating concentration-dependent variations and complex relaxation mechanisms dominated by Maxwell-Wagner interfacial polarization. The optimized P2 formulation (10 wt % PEDOT: PSS) exhibited superior electrochemical performance, maintaining the highest capacitance values and achieving a peak dissipation factor (tan δ) of 0.43 ± 0.02 at day 15, representing a 185 % enhancement over unmodified GFRC. EDX analysis confirmed successful polymer incorporation, with P2 exhibiting the highest carbon content (5.8 wt %) and sulfur content (1.8 wt %), indicating optimal dispersion. Equivalent circuit models were established and validated (R2 > 0.98), providing insights into complex charge transport mechanisms within this hybrid material. Microstructural analyses via scanning electron microscopy revealed significant morphological modifications, including the formation of crystalline and plate-like structures, while complementary FT-IR and TGA analyses confirmed polymer-cement interaction stability and thermal stability up to 450 °C. These findings establish fundamental design principles for creating electrically conductive cementitious materials with tunable dielectric properties, enabling strategic deployment in innovative infrastructure systems, energy storage devices, and electromagnetic shielding technologies.