Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Dimensionality Effects in Anisotropic Single Layers TiSe5 and TiTe5: a Comparative Study of 2D Sheets and 1D Nanochains(IOP Publishing Ltd, 2026) Can Dogan, Kadir; Kutay Tamdogan, Omer; Bozkurt, Yagmur; Cetin, Zebih; Yagmurcukardes, MehmetIn this study, we present a comprehensive first-principles investigation of the structural, vibrational, and electronic properties of titanium pentachalcogenide structures in both two-dimensional (2D) and one-dimensional (1D) nanochain (NC) forms. Total energy and geometry optimizations reveal that the 2D TiX5 (X = Se, Te) structures exhibit in-plane anisotropy arising from the trigonal prismatic TiX3 units interconnected via the chalcogenide chains. Phonon band dispersions and elastic tensor elements confirm the dynamical and mechanical stability of the 2D layers, respectively. Electronically, while TiTe5 is a metal, TiSe5 possesses direct band gap semiconducting behavior. In addition, free-standing 1D NC counterparts, which are sub-units of the 2D structures, are investigated by means of their stability. Three stable 1D NCs, namely TiTe5-NC, TiSe7-NC, and TiTe7-NC, are found to be composed of edge-sharing TiX6-like units with either five- or seven-fold coordination. The dynamically stable 1D NCs are shown to be semiconductors with relatively larger band gaps as compared to 2D layers. Predicted Raman spectra reveal clear signatures of vibrational mode evaluations as a result of quantum confinement from the 2D layer to the 1D NC. Moreover, finite-temperature ab-initio quantum molecular dynamics simulations at 300 K confirm the thermal stability of both the 2D TiX5 layers and 1D NC derivatives, showing that the Ti-based systems retain their structural integrity under ambient conditions and are feasible candidates for experimental synthesis. Our findings highlight the formation of stable semiconducting 1D NCs of Ti-pentachalcogenides from their 2D counterparts.Article Citation - WoS: 10Citation - Scopus: 9Quantifying Hydrogen Bonding Using Electrically Tunable Nanoconfined Water(Nature Portfolio, 2025) Wang, Ziwei; Bhattacharya, Anupam; Yagmurcukardes, Mehmet; Kravets, Vasyl; Diaz-Nunez, Pablo; Mullan, Ciaran; Mishchenko, ArtemHydrogen bonding plays a crucial role in biology and technology, yet it remains poorly understood and quantified despite its fundamental importance. Traditional models, which describe hydrogen bonds as electrostatic interactions between electropositive hydrogen and electronegative acceptors, fail to quantitatively capture bond strength, directionality, or cooperativity, and cannot predict the properties of complex hydrogen-bonded materials. Here, we introduce a concept of hydrogen bonds as elastic dipoles in an electric field, which captures a wide range of hydrogen bonding phenomena in various water systems. Using gypsum, a hydrogen bond heterostructure with two-dimensional structural crystalline water, we calibrate the hydrogen bond strength through an externally applied electric field. We show that our approach quantifies the strength of hydrogen bonds directly from spectroscopic measurements and reproduces a wide range of key properties of confined water reported in the literature. Using only the stretching vibration frequency of confined water, we can predict hydrogen bond strength, local electric field, O-H bond length, and dipole moment. Our work also introduces hydrogen bond heterostructures - a class of electrically and chemically tunable materials that offer stronger, more directional bonding compared to van der Waals heterostructures, with potential applications in areas such as catalysis, separation, and energy storage.Article Citation - WoS: 1Anisotropic Structural, Vibrational, Electronic, Optical, and Elastic Properties of Single-Layer Hafnium Pentatelluride: an <i>ab Initio</I> Study(Royal Soc Chemistry, 2024) Dogan, Kadir Can; Cetin, Zebih; Yagmurcukardes, MehmetMotivated by the highly anisotropic nature of bulk hafnium pentatelluride (HfTe<INF>5</INF>), the structural, vibrational, electronic, optical, and elastic properties of single-layer two-dimensional (2D) HfTe<INF>5</INF> were investigated by performing density functional theory (DFT)-based first-principles calculations. Total energy and geometry optimizations reveal that the 2D single-layer form of HfTe<INF>5</INF> exhibits in-plane anisotropy. The phonon band structure shows dynamic stability of the free-standing layer and the predicted Raman spectrum displays seven characteristic Raman-active phonon peaks. In addition to its dynamic stability, HfTe<INF>5</INF> is shown to exhibit thermal stability at room temperature, as confirmed by quantum molecular dynamics simulations. Moreover, the obtained elastic stiffness tensor elements indicate the mechanical stability of HfTe<INF>5</INF> with its orientation-dependent soft nature. The electronic band structure calculations show the indirect-gap semiconducting behavior of HfTe<INF>5</INF> with a narrow electronic band gap energy. The optical properties of HfTe<INF>5</INF>, in terms of its imaginary dielectric function, absorption coefficient, reflectance, and transmittance, are shown to exhibit strong in-plane anisotropy. Furthermore, structural analysis of several point defects and their oxidized structures was performed by means of simulated STM images. Among the considered vacancy defects, namely , , V<INF>Te<INF>out</INF></INF>, V<INF>Te<INF>in</INF></INF>, , and V<INF>Hf</INF>, the formation of V<INF>Te<INF>out</INF></INF> is revealed to be the most favorable defect. While and V<INF>Hf</INF> defects lead to local magnetism, only the oxygen-substituted V<INF>Hf</INF> structure possesses magnetism among the oxidized defects. Moreover, it is found that all the bare and oxidized vacant sites can be distinguished from each other through the STM images. Overall, our study indicates not only the fundamental anisotropic features of single-layer HfTe<INF>5</INF>, but also shows the signatures of feasible point defects and their oxidized structures, which may be useful for future experiments on 2D HfTe<INF>5</INF>.Correction Chlorinated Phosphorene for Energy Application (vol 231, 112625, 2024)(Elsevier, 2024) Hassani, Nasim; Yagmurcukardes, Mehmet; Peeters, Francois M.; Neek-Amal, Mehdi[No Abstract Available]Correction Chlorinated Phosphorene for Energy Application (vol 231, 112625, 2024)(Elsevier, 2024) Hassani, Nasim; Yagmurcukardes, Mehmet; Peeters, Francois M.; Neek-Amal, Mehdi[No Abstract Available]