Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Author: search.filters.author.Yagmurcukardes, MehmetScopus Q: search.filters.scopusQuartile.Q1

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  • Article
    Citation - WoS: 10
    Citation - Scopus: 9
    Quantifying Hydrogen Bonding Using Electrically Tunable Nanoconfined Water
    (Nature Portfolio, 2025) Wang, Ziwei; Bhattacharya, Anupam; Yagmurcukardes, Mehmet; Kravets, Vasyl; Diaz-Nunez, Pablo; Mullan, Ciaran; Mishchenko, Artem
    Hydrogen 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: 1
    Anisotropic 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, Mehmet
    Motivated 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>.