Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

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Author: search.filters.author.Islam, Md MahbubulPublication Index: search.filters.publicationIndex.Scopus

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  • Article
    Molecular Dynamics Study on the Coupled Effects of Size and Pre-Existing Oxide Layer on the Compressive Mechanical Properties of Copper Nanowires
    (Elsevier, 2026) Aral, Gurcan; Islam, Md Mahbubul; Amodeo, Jonathan
    Copper nanowires generally exhibit a native oxide shell layer, which can significantly impact their performance and reliability, especially in nanoelectronics applications. Using molecular dynamics simulations with the variable charge ReaxFF potential, we systematically examine the effects of pre-existing oxide layers on the mechanical properties and deformation mechanisms of [001]-oriented Cu nanowires with varying diameters at room temperature. Our findings reveal a size-dependent influence of the native oxide layer on the mechanical behavior. Specifically, the formation of an oxide shell (CuxOy) around the Cu core reduces the activation barrier for defect nucleation, reducing yield properties and, thereby, weakening the nanowires. This effect is more pronounced in smaller samples due to the intensified interaction between the metallic core and the oxide shell. Additionally, while the strength, elastic modulus, and yield stress increase with the diameter of pristine and oxidized specimens, pristine nanowires consistently exhibit superior mechanical properties when compared to their oxidized counterparts. The degradation in mechanical performance primarily stems from the early onset of plasticity initiated at the oxidized surface. These findings emphasize the detrimental impact of native oxide layers on the mechanical behavior of Cu nanowires and highlight the critical role played by size upon the mechanical properties of nano-oxidized metal samples. This work provides valuable insights into tailoring the mechanical properties of Cu nanowires, contributing to the optimization of their performance in both nanoelectronics and mechanical applications.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Effect of Oxidation on Mechanical Properties of Copper Nanowire: a Reaxff (reactive Force Field) Molecular Dynamics Study
    (Aip Publishing, 2023) Aral, Gürcan; Islam, Md Mahbubul
    Nanostructures with high surface area to volume ratio, such as oxidized and coated Cu nanowires (NWs), exhibit unique mechanical properties due to their size and surface effects. Understanding the complex oxidation process of Cu NWs at nanoscale and quantifying its resulting effects on mechanical behavior and properties are significantly essential for effective usage of Cu NW devices in a wide range of applications in nanoelectronics. Here, we perform molecular dynamics simulations using ReaxFF (reactive force field) to investigate the oxidation process and mechanisms of [001]-oriented cylindrical Cu NWs and its contribution on the mechanical deformation behavior and material properties as a function of NW sizes. The relatively thin oxide CuxOy layer is formed on the surface of Cu NWs in an O-2 environment, creating a core/shell (Cu/CuxOy) NW structure that played a key role in governing the overall tensile mechanical deformation behavior and properties of Cu NW. The formation of oxide layer effects, including the resulting interface and defects, leads to a reduction in the initial dislocation nucleation barrier, which facilitates the onset of plasticity and stress relaxation, ultimately resulting in a negative impact on the tensile strength, Young's modulus, yield stress and strain, and flow stress when compared to pristine counterparts. It is worth noting that the tensile mechanical response and properties of the Cu NWs are highly dependent on the pre-existing oxide shell layer associated with the size of NW, determining the overall mechanical performance and properties of Cu NWs.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Atomic-Scale Investigation of the Effect of Surface Carbon Coatings on the Oxidation and Mechanical Properties of Iron Nanowires
    (Royal Society of Chemistry, 2021) Aral, Gürcan; Islam, Md Mahbubul
    The understanding of the complex atomistic-scale mechanisms of the oxidation process of carbon (C) coated iron nanowires (Fe NW) and also the resulting modulation of mechanical properties is a highly challenging task. We perform reactive molecular dynamics (RMD) simulations based on the ReaxFF force field to investigate the mechanisms of the oxidation process of [001]-oriented pristine cylindrical Fe NWs with and without a C coating in an O2 environment in order to obtain detailed insights into the influences of the surface C coating on the oxidation process at room temperature. Here, we show that the C-coated shell layer on the free surface of pristine Fe NWs partially controls the spontaneous oxidation when exposed to O2 molecules by hindering the absorption-dissociation of O2 molecules and diffusion of O ions into the shell layer. In particular, the surface modification of the pristine Fe NW with the C-coated shell layer has pronounced effects on the improvement of oxidation resistance by lowering the surface reactivity, which limits the formation of an oxide shell layer on the free surface of the NW. The formation of strong Fe-C bonds in the C-coated shell layer largely restrains the oxidation process. Furthermore, to examine the influence of the C-coated shell layer on the resulting modulation of mechanical properties of the pristine Fe NW, we systematically investigate the mechanical deformation processes and related properties of Fe NW with and without a C coating including their oxidized counterparts subjected to both uniaxial tensile and compressive loads at room temperature. The yield stress and strain (the elastic limit) of Fe NWs including the elastic and plastic deformation phase of the stress-strain relationship are found to be sensitive to the loading modes, the existence of the C-coated shell layer and the resulting formation of an oxide shell layer on the surface of the C-coated Fe NW.
  • Article
    Citation - WoS: 8
    Citation - Scopus: 8
    Atomistic Insights on the Influence of Pre-Oxide Shell Layer and Size on the Compressive Mechanical Properties of Nickel Nanowires
    (American Institute of Physics, 2019) Aral, Gürcan; Islam, Md Mahbubul; Wang, Yun-Jiang; Ogata, Shigenobu; van Duin, Adri C. T.
    We used ReaxFF reactive molecular dynamics simulations to systematically investigate the effects of a pre-oxide shell layer on the mechanical properties of [001]-oriented nickel (Ni) nanowires (NWs) under the uniaxial compressive loading at room temperature. The pristine Ni NWs are considered as references to compare the mechanical properties of the oxide-coated NWs. We found that the mechanical properties of pristine Ni NWs under uniaxial compression are sensitive to both the diameter of the NWs and the pre-oxide shell layer, and their combined effect determines the overall stress and strain behaviors. The compressive strength of the pristine NWs decreases significantly with the decreasing diameter. We observe that the native defected amorphous pre-oxide shell layer with similar to 1.0 nm thickness leads to a lowering of the mechanical compressive resistivity of NWs and causes additional softening. Oxide-coated NWs exhibit a lesser size-dependent unique properties and a lower overall yield strength compared to their pristine counterparts. The reduction of the mechanical compressive yield stress and strain with the decreasing diameter is due to the substantial changes in plastic flow as well as correlated with the existence of the pre-oxide shell layer as compared to its pristine counterpart. Particularly, pre-oxide shell layers have pronounced effects on the initiation of initial dislocations to onset plastic deformation and consequently on the overall plastic response. Published under license by AIP Publishing.
  • Article
    Citation - WoS: 24
    Citation - Scopus: 26
    Role of Surface Oxidation on the Size Dependent Mechanical Properties of Nickel Nanowires: a Reaxff Molecular Dynamics Study
    (Royal Society of Chemistry, 2017) Aral, Gürcan; Islam, Md Mahbubul; Van Duin, Adri C. T.
    Highly reactive metallic nickel (Ni) is readily oxidized by oxygen (O2) molecules even at low temperatures. The presence of the naturally resulting pre-oxide shell layer on metallic Ni nano materials such as Ni nanowires (NW) is responsible for degrading the deformation mechanisms and related mechanical properties. However, the role of the pre-oxide shell layer on the metallic Ni NW coupled with the complicated mechanical deformation mechanism and related properties have not yet been fully and independently understood. For this reason, the ReaxFF reactive force field for Ni/O interactions was used to investigate the effect of surface oxide layers and the size-dependent mechanical properties of Ni NWs under precisely controlled tensile loading conditions. To directly quantify the size dependent surface oxidation effect on the tensile mechanical deformation behaviour and related properties for Ni NWs, first, ReaxFF-molecular dynamics (MD) simulations were carried out to study the oxidation kinetics on the free surface of Ni NWs in a molecular O2 environment as a function of various diameters (D = 5.0, 6.5, and 8.0 nm) of the NWs, but at the same length. Single crystalline, pure metallic Ni NWs were also studied as a reference. The results of the oxidation simulations indicate that a surface oxide shell layer with limiting thickness of ∼1.0 nm was formed on the free surface of the bare Ni NW, typically via dissociation of the O-O bonds and the subsequent formation of Ni-O bonds. Furthermore, we investigated the evolution of the size-dependent intrinsic mechanical elastic properties of the core-oxide shell (Ni/NixOy) NWs by comparing them with their un-oxidized counterparts under constant uniaxial tensile loading. We found that the oxide shell layer significantly decreases the mechanical properties of metallic Ni NW as well as facilitates the initiation of plastic deformation as a function of decreasing diameter. The disordered oxide shell layer on the Ni NW's surface remarkably reduces the yield stress and Young's modulus, due to the increased softening effects with the decreasing NW diameter, compared to un-oxidized counterparts. Moreover, the onset of plastic deformation occurs at a relatively low yielding strain and stress level for the smaller diameter of oxide-coated Ni NWs in comparison to their pure counterparts. Furthermore, for pure Ni NWs, Young's modulus, the yielding stress and strain slightly decrease with the decrease in the diameter size of Ni NWs.