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Rippling Instability On Surfaces Of Stressed Crystalline Conductors, Dimitrios Maroudas, M. R. Gungor, V. Tomar
Rippling Instability On Surfaces Of Stressed Crystalline Conductors, Dimitrios Maroudas, M. R. Gungor, V. Tomar
Dimitrios Maroudas
We report a surface morphological stability analysis for stressed, conducting crystalline solids without and with the simultaneous application of an electric field based on self-consistent dynamical simulations according to a fully nonlinear model. The analysis reveals that in addition to a cracklike surface instability, a very-long-wavelength instability may be triggered that leads to the formation of secondary ripples on the surface morphology. We demonstrate that the number of ripples formed scales linearly with the wavelength of the initial perturbation from the planar surface morphology and that a sufficiently strong electric field inhibits both the cracklike and the rippling instability.
Analysis Of Diamond Nanocrystal Formation From Multiwalled Carbon Nanotubes, Dimitrios Maroudas, E. S. Aydil, T. Singh, A. R. Muniz
Analysis Of Diamond Nanocrystal Formation From Multiwalled Carbon Nanotubes, Dimitrios Maroudas, E. S. Aydil, T. Singh, A. R. Muniz
Dimitrios Maroudas
A systematic analysis is presented of the nanocrystalline structures generated due to the intershell C-C bonding between adjacent concentric graphene walls of multiwalled carbon nanotubes (MWCNTs). The analysis combines a comprehensive exploration of the entire parameter space determined by the geometrical characteristics of the individual graphene walls comprising the MWCNT with first-principles density-functional theory calculations of intershell C-C bonding and structural relaxation by molecular-dynamics simulation of the resulting nanocrystalline structures. We find that these structures can provide seeds for the nucleation of the cubic-diamond and hexagonal-diamond phase in the form of nanocrystals embedded in the MWCNTs. The resulting lattice structure …
Comparative Study Of The Mechanical Behavior Under Biaxial Strain Of Prestrained Face-Centered Cubic Metallic Ultrathin Films, Dimitrios Maroudas, M. R. Gungor, K. Kolluri
Comparative Study Of The Mechanical Behavior Under Biaxial Strain Of Prestrained Face-Centered Cubic Metallic Ultrathin Films, Dimitrios Maroudas, M. R. Gungor, K. Kolluri
Dimitrios Maroudas
We report a molecular-dynamics study of the mechanical response to dynamic biaxial tensile straining of nanometer-scale-thick Al, Cu, and Ni films. We find that the mechanical behavior of such films of face-centered cubic metals with moderate-to-high propensity for stacking-fault formation (Cu and Ni) is significantly different from those where such propensity is low (Al). The plastic strain rate in Cu and Ni films is greater than that in Al ones, leading to an extended easy-glide stage in Cu and Ni but not in Al films. These differences arise due to the different dislocation annihilation mechanisms in the two film categories.
Molecular-Dynamics Simulations Of Stacking-Fault-Induced Dislocation Annihilation In Prestrained Ultrathin Single-Crystalline Copper Films, Dimitrios Maroudas, K. Kolluri, M. R. Gungor
Molecular-Dynamics Simulations Of Stacking-Fault-Induced Dislocation Annihilation In Prestrained Ultrathin Single-Crystalline Copper Films, Dimitrios Maroudas, K. Kolluri, M. R. Gungor
Dimitrios Maroudas
We report results of large-scale molecular-dynamics simulations of dynamic deformation under biaxial tensile strain of prestrained single-crystalline nanometer-scale-thick face-centered cubic (fcc) copper films. Our results show that stacking faults, which are abundantly present in fcc metals, may play a significant role in the dissociation, cross slip, and eventual annihilation of dislocations in small-volume structures of fcc metals. The underlying mechanisms are mediated by interactions within and between extended dislocations that lead to annihilation of Shockley partial dislocations or formation of perfect dislocations. Our findings demonstrate dislocation starvation in small-volume structures with ultrathin film geometry, governed by a mechanism other than …
Kinetic Monte Carlo Simulations Of Surface Growth During Plasma Deposition Of Silicon Thin Films, Dimitrios Maroudas, T. Singh, S. Pandey
Kinetic Monte Carlo Simulations Of Surface Growth During Plasma Deposition Of Silicon Thin Films, Dimitrios Maroudas, T. Singh, S. Pandey
Dimitrios Maroudas
Based on an atomically detailed surface growth model, we have performed kinetic Monte Carlo (KMC) simulations to determine the surface chemical composition of plasma deposited hydrogenated amorphous silicon (a-Si:H) thin films as a function of substrate temperature. Our surface growth kinetic model consists of a combination of various surface rate processes, including silyl (SiH3) radical chemisorption onto surface dangling bonds or insertion into Si–Si surface bonds, SiH3 physisorption, SiH3 surface diffusion, abstraction of surface H by SiH3 radicals, surface hydride dissociation reactions, as well as desorption of SiH3, SiH4, and Si2H6 species into the gas phase. Transition rates for the …
On The Hydrogen Storage Capacity Of Carbon Nanotube Bundles, Dimitrios Maroudas, A. R. Muniz, M. Meyyappan
On The Hydrogen Storage Capacity Of Carbon Nanotube Bundles, Dimitrios Maroudas, A. R. Muniz, M. Meyyappan
Dimitrios Maroudas
An analytical model is presented to describe the effect of carbon nanotube (CNT) swelling upon hydrogenation on the hydrogen storage capacity of single-walled CNT bundles; the model is properly parameterized using atomistic calculations for the relationship between CNT swelling and the degree of hydrogenation as measured by the coverage of the CNTs by chemisorbed atomic H. The model generates experimentally testable hypotheses, which can be used to explain the lower H storage capacities reported for CNT bundles and the experimentally observed nonuniformity of hydrogenation of CNT bundles.