Antimonen nanotüplerin mekanik özellikleri ve hasar davranışlarının moleküler dinamik yöntemiyle incelenmesi
Investigation of the mechanical characteristics and failure behavior of antimonene nanotubes through molecular dynamics simulations
- Tez No: 957701
- Danışmanlar: PROF. DR. MESUT KIRCA
- Tez Türü: Yüksek Lisans
- Konular: Bilim ve Teknoloji, Makine Mühendisliği, Science and Technology, Mechanical Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 2025
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Lisansüstü Eğitim Enstitüsü
- Ana Bilim Dalı: Makine Mühendisliği Ana Bilim Dalı
- Bilim Dalı: Katı Cisimlerin Mekaniği Bilim Dalı
- Sayfa Sayısı: 111
Özet
Son yıllarda iki boyutlu (2B) monoelemental malzemelere yönelik artan ilgi ile birlikte, antimonene yapıların fiziksel özellikleri ve uygulama potansiyelleri dikkat çekici bir araştırma alanı haline gelmiştir. Bu tez çalışmasında, antimonenin kararlı iki allotropu olan α- (kırışık yapı, puckered structure) ve β- (bükülmüş yapı, buckled structure) fazlarına ait nanotüplerin (SbNT) mekanik özellikleri ve hasar davranışları, klasik moleküler dinamik simülasyonları kullanılarak kapsamlı bir şekilde incelenmiştir. Sayısal analizler LAMMPS yazılımı ile gerçekleştirilmiştir. Çalışmada, SbNT'lerin nihai çekme mukavemeti, kırılma birim şekil değiştirmesi ve Young modülü gibi mekanik özellikleri, kiralite (koltuk tipi ve zikzak), çap, sıcaklık ve deformasyon hızı gibi değişkenler dikkate alınarak detaylı bir şekilde incelenmiştir. Tezin yöntem kısmında, SbNT'lerin atomistik modellenmesi, sınır koşulları, enerji minimizasyonu ve NPT topluluğu kullanılarak termal dengeleme işlemlerinin tanıtıldığı simülasyon detayları arz edilmiştir. Ayrıca, gerilme-birim şekil değiştirme ilişkilerinin virial gerilme analiziyle hesaplanma yöntemi sunulmuştur. Son olarak, atomlar arası etkileşimleri modellemek için simülasyonlarda kullanılan Stillinger Weber potansiyeli açıklanmıştır. Sayısal simülasyonlar, tüm SbNT numunelerinin nihai gerilme seviyesinden sonra yük taşıma kapasitesini tamamen kaybedilmesiyle gevrek bir kırılma sergilediğini ortaya koymuştur. Farklı çaplara sahip SbNT'lerin kırılgan doğası, farklı sıcaklık ve yükleme hızı koşullarında değişmemiştir. α-SbNT'ler, koltuk tipi ve zikzak yönlerdeki farklı kristal yapıları nedeniyle β-SbNT'lere kıyasla belirgin bir anizotropik mekanik davranış göstermektedir. Young modülünün sıcaklıkla değişimi kayda değer olmasa da yüksek sıcaklıklarda SbNT'lerin nihai çekme mukavemeti ve kırılma birim şekilde değiştirmesi önemli ölçüde azalmaktadır. Deformasyon hızı değişimlerinin ise nihai mukavemet ve elastisite modülünde önemli bir değişikliğe sebep olmazken, kırılma birim şekil değiştirmesi üzerinde daha belirgin etkisi olduğu belirlenmiştir. Ayrıca, çap arttıkça elastik modülde küçük bir artış gözlenmiştir. Özellikle, daha düşük kararlılığa sahip zikzak α-SbNT'lerde çap ve sıcaklığın etkileri daha belirgindir. Bu durum, zikzak α-SbNT'lerin kristal yapısının sıcaklık ve çap değişikliklerine karşı daha hassas olduğunu göstermektedir. Elde edilen bulgular, SbNT'lerin mekanik davranışlarının sıcaklık, çap, deformasyon hızı ve kiralite gibi parametrelere bağlı olarak nasıl değiştiğini ortaya koymuş ve bu malzemelerin mühendislik uygulamalarında kullanımı için temel bir çerçeve sağlamıştır. Bu tez çalışması, antimonen nanotüplerin temel mekanik özelliklerini kapsamlı bir şekilde inceleyerek, bu yapıların optoelektronik, nanoelektronik, enerji depolama ve biyomedikal uygulamalar gibi geniş bir yelpazede potansiyel kullanımlarına dair önemli bilgiler sunmaktadır.
Özet (Çeviri)
In recent years, the escalating interest in two-dimensional (2D) monoelemental materials has propelled antimonene structures into the spotlight of scientific research, driven by their exceptional physical properties and promising potential for diverse applications. Antimonene, a group VA element, exhibits unique attributes such as a tunable bandgap, high carrier mobility, and biocompatibility, positioning it as a compelling alternative to other 2D materials like graphene. This thesis undertakes a comprehensive investigation of the mechanical characteristics and failure behaviors of nanotubes derived from two stable allotropes of antimonene, namely the puckered (α SbNT) and buckled (β-SbNT) phases, utilizing classical molecular dynamics (MD) simulations. Numerical analyses were meticulously executed using the Large-Scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) software, a robust tool for atomistic simulations. The mechanical properties of antimonene nanotubes (SbNTs), encompassing ultimate tensile strength, fracture strain, and Young's modulus, were systematically examined by considering critical variables such as chirality (armchair and zigzag), diameter, temperature, and strain rate. These parameters were varied to probe their influence on the structural integrity and deformation mechanisms of SbNTs, providing a detailed understanding of their behavior under diverse conditions. The methodology employed in this thesis involved a rigorous simulation framework to ensure accurate and reproducible results. Atomistic modeling of SbNTs was performed to construct both α-SbNT and β-SbNT configurations, with variations in chirality (armchair and zigzag) and diameter to capture the structural diversity of these nanotubes. Periodic boundary conditions were applied to simulate an infinite system, minimizing edge effects and ensuring realistic behavior. Energy minimization was conducted using the conjugate gradient algorithm to achieve a stable initial configuration, free of residual stresses. Thermal equilibration followed, utilizing the isothermal-isobaric (NPT) ensemble to maintain constant temperature and pressure during the simulations. Temperatures, such as 300 K and higher, were systematically tested to evaluate thermal effects on mechanical properties. Uniaxial tensile deformation was then applied to the equilibrated structures, with strain rates varied (e.g., 108 s⁻¹) to assess the response of SbNTs under different loading speeds. Stress strain relationships were calculated using the virial stress tensor, a reliable method for quantifying internal stresses at the atomic level. This approach allowed for precise determination of mechanical properties, including ultimate tensile strength and fracture strain, under varying conditions. To model interatomic interactions, the Stillinger-Weber potential was employed, specifically parameterized for antimonene to accurately represent the complex bonding characteristics of its puckered and buckled structures. This potential accounts for both two-body and three-body interactions, capturing the angular dependencies critical to the stability of α-SbNT and β-SbNT. Supporting tools, such as MATLAB, were utilized to generate atomic coordinates, with a specific script for zigzag β-SbNT detailed in Appendix C of the thesis. Visualization of deformation processes and axial stress distributions was facilitated by OVITO software, with representative results at 300 K presented in Appendix A, highlighting stress concentrations and failure patterns. Numerical simulations revealed consistent and insightful findings regarding the behavior of SbNTs. All SbNT specimens exhibited brittle failure, characterized by a complete loss of load-bearing capacity following the attainment of ultimate stress levels. This brittle nature persisted across samples with varying diameters, under diverse temperature and loading rate conditions, underscoring the inherent rigidity of these nanostructures. The α-SbNT variants, due to their distinct crystal structures in the armchair and zigzag directions, demonstrated pronounced anisotropic mechanical behavior compared to their β-SbNT counterparts. The puckered configuration of α SbNT results in differing atomic arrangements along these directions, leading to direction-dependent responses under tensile loading. In contrast, the buckled structure of β-SbNT, with its more symmetric lattice, exhibited relatively uniform mechanical properties, suggesting greater structural consistency. While the variation in Young's modulus with temperature was not substantial, indicating a degree of stability in elastic properties, the ultimate tensile strength and fracture strain of SbNTs experienced significant deterioration at elevated temperatures. This decline is attributed to intensified thermal vibrations, which disrupt interatomic bonds, weaken structural integrity, and accelerate the onset of failure. For example, at higher temperatures, the increased kinetic energy of atoms reduces the capacity of SbNTs to sustain tensile loads, leading to lower strength and strain values. Variations in strain rate, however, did not induce significant changes in ultimate strength or elastic modulus, suggesting that these properties are relatively insensitive to loading speed within the tested range. In contrast, the fracture strain exhibited a more pronounced sensitivity to strain rate, with higher rates often reducing ductility due to limited time for atomic rearrangement and stress relaxation. Additionally, an increase in nanotube diameter was observed to result in a slight enhancement of the elastic modulus, likely attributable to reduced curvature effects and a more stable structural framework in larger nanotubes. This trend was evident across both allotropes, though the effects of diameter and temperature were particularly pronounced in zigzag α-SbNT, which possesses lower stability compared to β-SbNT. The puckered crystal structure of zigzag α-SbNT renders it more susceptible to perturbations induced by temperature fluctuations and dimensional changes, as evidenced by axial stress distributions in Appendix A. These distributions, calculated at 300 K, highlight stress concentrations at strain levels such as 21–23% for armchair α-SbNT and 26–28% for zigzag α-SbNT, marking the precursors to brittle failure. These findings collectively elucidate how the mechanical behavior of SbNTs varies as a function of temperature, diameter, strain rate, and chirality, providing a fundamental framework for their application in engineering contexts. The observed trends underscore the importance of tailoring structural parameters and operating conditions to optimize the performance of SbNTs in practical scenarios. This thesis work comprehensively elucidates the fundamental mechanical properties of antimonene nanotubes, offering critical insights into their potential utilization across a broad spectrum of applications, including optoelectronics, nanoelectronics, energy storage, and biomedical engineering. The consistent brittle failure observed across all tested conditions highlights the need for careful consideration of environmental and loading factors in the design of SbNT-based systems. The pronounced anisotropy of α-SbNT, driven by its puckered structure, contrasts with the more stable behavior of β-SbNT, providing valuable guidance for selecting appropriate allotropes for specific applications. The significant reduction in ultimate tensile strength and fracture strain at elevated temperatures emphasizes the sensitivity of SbNTs to thermal effects, while the slight increase in elastic modulus with diameter suggests opportunities for structural optimization. The relative insensitivity of strength and modulus to strain rate, coupled with the notable impact on fracture strain, further informs the operational limits of these materials. The heightened sensitivity of zigzag α-SbNT to diameter and temperature variations underscores its lower stability, a critical consideration for applications requiring robust performance. The methodologies employed, including the use of the Stillinger-Weber potential, virial stress analysis, and LAMMPS-based MD simulations, ensure a robust and reproducible approach to characterizing SbNTs. These findings contribute significantly to the growing body of knowledge on 2D monoelemental materials, bridging the gap between theoretical simulations and practical implementation. By systematically analyzing the interplay of structural and environmental parameters, this research establishes a foundational understanding of the mechanical performance of antimonene nanotubes, paving the way for their tailored application in advanced technological domains. Future studies may build upon this work by exploring additional parameters, such as defects or chemical functionalization, to further enhance the utility of SbNTs in real-world engineering applications.
Benzer Tezler
- Lityum iyon piller için fiziksel buhar biriktirme yöntemi ile metaloksit-karbon kompozit anotların geliştirilmesi
Development of metaloxide-carbon composite anodes by physical vapor deposition method for lithium ion batteries
ÖZGÜR CEVHER
Doktora
Türkçe
2014
Metalurji MühendisliğiSakarya ÜniversitesiMetalurji ve Malzeme Mühendisliği Ana Bilim Dalı
PROF. DR. HATEM AKBULUT
- Effects of nanoadditives and different conventional flame retardants on the flammability of polystyrene
Nanokatkı malzemeleri ve farklı geleneksel alev geciktiricilerin polistirenin alevlenme davranışına etkileri
BENGÜ MELİKE SİPAHİOĞLU
Yüksek Lisans
İngilizce
2012
Metalurji MühendisliğiOrta Doğu Teknik ÜniversitesiMetalurji ve Malzeme Mühendisliği Ana Bilim Dalı
PROF. DR. CEVDET KAYNAK
- Tungsten ve antimon oksit nanoparçacıklar temelli yeni bir kompozit elektrot kullanılarak ilaç örneklerinde parasetamolun voltametrik tayini
Voltammetric determination of paracetamol in pharmaceuticals using a novel composite electrode based on nanoparticles of tungsten and antimony oxide
MOHAMMED HUSSEIN FATTAH
- Antimonun ateşte rafinasyonunda demir ve arseniğin davranışı
Behavior of iron and arsenic during fire-refining of antimony
ERCAN AÇMA
- Assessment of antimony as a priority pollutant and exploration of antimony removal from aquatic environment
Antimonun öncelikli kirletici olarak değerlendirilmesi ve sucul ortamdan antimon gideriminin incelenmesi
ÖZGE YÜCEL
Yüksek Lisans
İngilizce
2017
Çevre MühendisliğiOrta Doğu Teknik ÜniversitesiÇevre Mühendisliği Ana Bilim Dalı
YRD. DOÇ. DR. DERYA DURSUN BALCI