Date of Graduation

Fall 2019

Degree

Master of Science in Materials Science

Department

Physics, Astronomy, and Materials Science

Committee Chair

Ridwan Sakidja

Keywords

α-rhombohedral boron, amorphous boron carbide, hydrogenated boron carbide, molecular dynamics, HRMC, Stillinger-Weber potential, ReaxFF, short-range order

Subject Categories

Ceramic Materials | Condensed Matter Physics | Materials Chemistry | Other Materials Science and Engineering

Abstract

We present a computational study of amorphous boron carbide (a-BxC) models using Molecular Dynamics (MD) studied with Stillinger-Weber (SW) and ReaxFF potential. The atomic structure factor (S(Q)), radial distribution function (RDF) and bond lengths comparison with other experimental and ab initio models shows that a random arrangement of icosahedra (B12, B11C) interconnected by chains (CCC, CBC) are present in a-BxC. Afterward, Hybrid Reverse Monte Carlo (HRMC) technique is used to recreate a-BxC structures. The existing SW potential parameters of Boron are optimized for the α-rhombohedral (Icosahedral B12) boron structure using potential energy minimization and incorporated into HRMC. The a-BxC modeled from MD simulation is used as a sample for experimental input parameters like RDF, S(Q), coordination environments (CO), bond angle distribution (B(θ)) and bond length (BL) to guide initial configuration and simulation in HRMC. An accurate agreement of structural information between HRMC and MD generated models was found. Also, we have modeled the amorphous hydrogenated boron carbide (a-BxC:Hy) material using MD simulation to determine the structural characteristics of experimentally prepared a-BxC:Hy using plasma-enhanced chemical vapor deposition (PECVD) technique. The simulated a-BxC:Hy models are characterized for RDF, S(Q), B(θ), CO, Structural units (SU), and CO information. The key structural features of a-BxC:Hy is mapped out with the density, hydrogen concentration and the stoichiometry of experimentally prepared films prepared using single-source precursor ortho-carborane.

Copyright

© Rajan Khadka

Available for download on Wednesday, December 01, 2021

Open Access

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