arXiv subjects

G. Baghdasaryan

Publications and source records attributed to G. Baghdasaryan.

3 recordsLinked to original sources

arXiv2026

Enhancement of mechanical properties of graphene oxide fibers via liquid crystalline phase formation and flake size optimization

Graphene oxide (GO) fibers are promising materials for lightweight, high-strength applications due to their unique structural tunability and mechanical performance. However, the properties of GO fibers strongly depend on the ordering of GO flakes during the assembly process. In this work, we demonstrate that GO fibers spun from a liquid crystalline (LC) GO dispersion exhibit significantly enhanced mechanical properties compared to those produced from non-LC GO dispersions. The improved tensile strength is attributed to the larger GO flake size and highly ordered alignment achieved in the LC phase. The LC-derived fibers demonstrated a Young's modulus of 12.3 GPa, a tensile strength of 146.8 MPa, and an elongation at break of 2.5%. These findings emphasize the critical role of flake size and LC ordering in enhancing the performance of GO-based fibers and suggest a straightforward pathway toward scalable fabrication of strong yet flexible carbon-based materials.

cond-mat.mtrl-sci↗

arXiv2025

Revisiting THz absorption in GO and rGO liquid crystalline films

With a swift progress in modern high-throughput communication systems, security, sensing and medicine utilizing THz range technologies, the demand for easy-to-fabricate, lightweight and high-performance absorbing materials has increased drastically. Notably, traditional approaches of eliminating unwanted radiation based on metasurfaces often face fabrication challenges limiting their practicality. In this study, we propose a straightforward approach for fabricating graphene oxide (GO) and reduced graphene oxide (rGO) liquid crystalline (LC) films via the vacuum filtration method and investigate their THz absorption characteristics. Here, the presence of LC phase in our electrochemically exfoliated GO and rGO LC films was confirmed by ellipsometric characterization. THz time-domain spectroscopy (TDS) measurements reveal that these films possess a low reflectance and transmittance confirming their strong absorptive properties within 0.4 - 1.6 THz frequency range for 2 micrometer thick GO and rGO LC films. Particularly, the GOLC film shows 37 % average absorption at a thickness of 2.12 micrometer, which is 221 times smaller than the central wavelength. Similarly, the rGOLC film reaches 50 % absorption with a 1.68 micrometer thickness, 279 times smaller than the central wavelength. These findings provide valuable insights for development of GO- and rGO-based LC THz absorbers with highly tunable properties due to the ordering of GO flakes. Specifically, the LC phase of GO contributes to the formation of more uniform films with enhanced absorption due to the compact stacking and denser packing, compared to conventional GO films with randomly oriented GO flakes.

cond-mat.mtrl-sci↗

arXiv2025

L-Cysteine Polymorph Coatings for THz Sensing Metasurfaces

The electromagnetic response of metasurfaces can be intentionally engineered by carefully designing their unit cells. Narrowband metasurfaces, characterized by high quality factors, can serve as an efficient platform for biosensing in optical to THz regimes, to explore new structural forms of biomolecules, further elevating the capabilities of THz sensing technologies. In this study, an all-metallic metasurface featuring structural asymmetry is proposed to analyze L-Cysteine with orthorhombic and monoclinic crystallographic structures. The influence of the concentration of L-Cysteine in the monoclinic phase on the THz response of the metasurface was performed using a drop-casting method. Our findings reveal a noticeable frequency shift as analyte concentration raises, underscoring the potential for high sensitivity in detecting biomolecules. Thus, this research demonstrates that asymmetric THz metasurfaces offer rather promising detection capabilities at lower THz frequencies between two crystallographic structures of L Cysteine, with a Q-factor of 37, and a sensitivity of 1.430 THz ml/g. We believe that our results can be of great value to the development of biosensors for improved material characterization at low frequencies.

physics.optics↗