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Showing 1 to 20 of 22 for “"vacancy formation"”.
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Equilibrium vacancy formation in crystalline neon
Submitted by William Weathers (weathrs2@illinois.edu) on 2012-03-09T18:59:55Z No. of bitstreams: 1 1971_schoknecht.pdf: 8152794 bytes, checksum: b81e5f234bb4eeae6adbefb991f03950 (MD5)
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X -Ray and Pressure Measurements on Helium Solids
… National Laboratory are also presented here. The vacancy formation energy of fcc 4He at 10.4 cm3 /mol was obtained by two different methods. In addition, c/a ratios were determined to be ideal for hcp 4He and hcp 3He near 10 cm3/mol.
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The Development of Empirical Potentials From First-Principles and Application to Al Alloys
… grain-boundaries. Cu segregation raises that vacancy formation and diffusion activation energies at $\Sigma$11 grain boundaries.
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MAX phases as an electrocatalyst support material: a DFT study
… most electrically conductive of the three. The vacancy formation energy of an A group atom was investigated using a 2 x 2 x 2 supercell. The vacancy formation energies were calculated to be 2.882 eV for Ti2AlC, 2.812 eV for Ti3AlC2, and 2.167 eV for Ti3SiC2. The formation of a vacancy increases …
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It's Not a SKZCAM! Accurate Surface Chemistry at Low Cost
… quantities like the adsorption energy and oxygen vacancy formation energy to be calculated. Consistently achieving accurate predictions will require going beyond the standard density functional theory (DFT) to methods like coupled cluster theory with single, double, and perturbative triple …
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Influence of Electronic Structure and Lattice Dynamics on Oxygen Ion Transport in Solid-State Ionic Conductors
… and phonons. The results are extended to the formation of oxygen vacancies and interstitials in perovskite and RuddlesdenPopper oxides. We find that defect formation energy rises with defect formation entropy, which is linked to electronic energy states interacting with phonons. In perovskite …
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CO oxidation catalysis with substituted ceria nanoparticles
… activity of CuO/CeO₂ catalysts. The oxygen-ion vacancy formation energy is introduced as an activity descriptor to rationalize trends in the catalytic activities measured for MyCe₁-yO₂-x nanoparticles that span over three orders of magnitude. As such, the DFT-calculated vacancy formation energy …
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Structure-Sensitivity of CO Oxidation Over Supported Pt Catalysts in the Subnanometer Regime and Its Origin
… activation at the Pt-TiO2 interface and oxygen vacancy creation are rate-limiting steps, with activation energy for oxygen vacancy formation decreasing by 19 kJ/mol as average Pt size increases from 0.9 nm to 1.8 nm. This was further corroborated by temperature-programmed reduction by CO, which …
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Halogen-induced modification of silicon surfaces: etching roughening, and step transformations
… including etching, roughening and step transformations. These investigations have focused on elucidating the atomic-level details associated with the evolution of terrace and step sites on Cl-Si(100)-(2x1) under conditions of halogen supersaturation. I present a novel adsorption mechanism …
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Atomistic model of void nucleation and growth during electromigration
Void formation due to electromigration is among the most significant reliability problems in the semiconductor industry. To help gain a better understanding of the atomistic processes involved in void formation under electromigration conditions we have used the Embedded Atom Method (BAM) to …
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Deep understanding of degradation in lithium ion batteries through experimental and first-principles study
… solid electrolyte interphase (SEI) layer formation, and mechanical fracture. To address these issues, applying an ultrathin coating onto active materials via Atomic Layer Deposition (ALD) is an efficient way. Although numerious works have been done for active material performance …
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Materials Design for Advanced Nuclear Energy Systems: Refractory High Entropy Alloys and Metallic Multilayer Composites
… also facilitates the correct calculation of the vacancy formation energy distribution in HEAs which gives insight to radiation damage, solid–state diffusion, and other vacancy–driven material behavior. To test the validity of the model, I synthesize and characterize 5 refractory HEA compositions: …
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Orbital-free density functional theory using higher-order finite differences
… for selected examples, one of which is the vacancy formation energy in Aluminum. Overall, we demonstrate that the proposed formulation and implementation is an attractive choice for performing OF-DFT calculations.
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Degradation of Cd-yellow pigment: an ab initio study of defects and adsorption of oxygen and water on CdS
… and electronic structures as well as the vacancy formation and adsorption energies are determined with the use of a first principles method. All the calculations are performed within the framework of the Density Functional Theory (DFT) in the Generalized Gradient Approximation (GGA-PBE) …
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Modeling of mechanisms affecting the growth and breakdown of iron sulfide films
… of several atomic-scale phenomena like defect formation and ionic diffusion that contribute to the growth and/or breakdown of the passive film, we construct a construct a novel multiscale modeling framework that explicitly models atomic scale phenomena and couples it to higher-length- scale …
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X-ray diffraction study of vacancies in bcc helium-3 and bcc helium-4
Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-06-13T17:02:41Z No. of bitstreams: 1 1982_granfors.pdf: 4976253 bytes, checksum: e552b132221ed1a25b853f6b916a974f (MD5)
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The Effects of Strain and Vacancies on the Electric and Vibrational Properties of Ferroelectric BaTiO3 from First-principles
… in this dissertation. First, the studies of vacancy formation energy are highlighted, which shows the type and charge character of the vacancy that are most likely to occur under any given growth conditions. Afterward, I present the effect of vacancies on polarization and polarization …
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Reliability Studies of TiN/Hf-Silicate Based Gate Stacks
… incident carrier energies above the calculated 0 vacancy formation threshold and thick high-[Kappa] layer, both flatband voltage shift, due to electron trapping at the deep levels, and increase in leakage current during stress follow t^n(n [asymptotic to] 0.4) power-law dependence under substrate …
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First-Principles Study of Band Alignment and Electronic Structure at Metal/Oxide Interfaces: An Investigation of Dielectric Breakdown
… interface. Point defects, such as oxygen vacancy (VO) and hydrogen impurity (IH), are introduced into the Al/c-SiO2 interface to study the effects on band offset and electronic structure caused by point defects at metal/oxide interfaces. It is shown that the bonding chemistry at …
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First-principles investigations of transition metal hyperdoped silicon and germanium for intermediate band engineering
… of substitutional and interstitial sites via vacancy formation and annihilation, is identified as the likely path for deactivation. Further, the experimentally observed lattice contraction is explained by the presence of vacancies and gold-vacancy complexes in excess concentrations. The …
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