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Surface Energy In Bond-Counting Models On Bravais And Non-Bravais Lattices, Tim Ryan Krumwiede May 2017

Surface Energy In Bond-Counting Models On Bravais And Non-Bravais Lattices, Tim Ryan Krumwiede

Doctoral Dissertations

Continuum models in computational material science require the choice of a surface energy function, based on properties of the material of interest. This work shows how to use atomistic bond-counting models and crystal geometry to inform this choice. We will examine some of the difficulties that arise in the comparison between these models due to differing types of truncation. New crystal geometry methods are required when considering materials with non-Bravais lattice structure, resulting in a multi-valued surface energy. These methods will then be presented in the context of the two-dimensional material graphene in a way that correctly predicts its equilibrium …


Synthesis And Fundamental Property Studies Of Energy Material Under High Pressure., Meysam Akhtar May 2017

Synthesis And Fundamental Property Studies Of Energy Material Under High Pressure., Meysam Akhtar

Electronic Theses and Dissertations

Recently, high-pressure science and technology has flourished and rapidly advanced to impact a wide domain of materials and physical sciences. One of the most substantial technological developments is the integration of samples at ultrahigh pressure with a wide range of in-situ probing techniques. Applications of extreme pressure have significantly enriched our understanding of the electronic, phonon, and doping effects on the newly emerged two-dimensional (2D) materials. Under high pressure, materials’ atomic volume radically decreases, and electronic density rises, which will lead to extraordinary chemical reaction kinetic and mechanisms. The promising capability of high pressure combine with the significance of novel …


High-Quality Chemical Vapor Deposition Graphene-Based Spin Transport Channels, Lester Florian Lampert Jan 2017

High-Quality Chemical Vapor Deposition Graphene-Based Spin Transport Channels, Lester Florian Lampert

Dissertations and Theses

Spintronics reaches beyond typical charge-based information storage technologies by utilizing an addressable degree of freedom for electron manipulation, the electron spin polarization. With mounting experimental data and improved theoretical understanding of spin manipulation, spintronics has become a potential alternative to charge-based technologies. However, for a long time, spintronics was not thought to be feasible without the ability to electrostatically control spin conductance at room temperature. Only recently, graphene, a 2D honeycomb crystalline allotrope of carbon only one atom thick, was identified because of its predicted, long spin coherence length and experimentally realized electrostatic gate tunability. However, there exist several challenges …


Spectroscopic And Microscopic Analysis Of Graphene For Sensor Applications, Tamanna Tasneem Khan Jan 2017

Spectroscopic And Microscopic Analysis Of Graphene For Sensor Applications, Tamanna Tasneem Khan

Open Access Theses & Dissertations

As a two-dimensional material, graphene shows very good thermal and electrical conductivities, which, with its unique optical properties, makes it suitable for a variety of applications. In this study, we present detailed investigations by confocal Raman and Drude model analysis of the material's changes and improvements, as it transitioned from 3D graphite to 2D graphene. Besides Raman spectral recording, which can detect single, a few, and multi-layers of graphene, confocal Raman mapping allows distinction of such domains and direct visualization of material inhomogeneity. Moreover, far-infrared transmittance measurements, which are related to electrical conductivity, demonstrate a distinct increase of conductivity with …


Dft Study Of Adsorption Of Trimetallic Endohedral Fullerenes On Graphene, Nakul Nitin Karle Jan 2017

Dft Study Of Adsorption Of Trimetallic Endohedral Fullerenes On Graphene, Nakul Nitin Karle

Open Access Theses & Dissertations

A density functional theory (DFT) study on the geometric and electronic structure of C60 and Sc3N@C80 along with their adsorption on pristine single layer graphene (SLG) is presented. C60 is found to adsorb in two nearly degenerate configurations: (i) with a pentagon facing the SLG, which is the most stable one, and (ii) with a hexagon facing the SLG in a face-to-face perfect alignment, rarely common in Ï?â??Ï? interactions, 0.06 eV higher in energy. The calculated binding energy of 0.76 eV, which includes dispersion effects, is in good agreement with previous theoretical and experimental reports. On the contrary, Sc3N@C80 adsorption …