scholarly journals Atomistic simulation of CeO2 surface hydroxylation: implications for glass polishing

2008 ◽  
Vol 43 (12) ◽  
pp. 4157-4162 ◽  
Author(s):  
Christopher R. Stanek ◽  
Averyl H. H. Tan ◽  
Scott L. Owens ◽  
Robin W. Grimes
Keyword(s):  
Atomistic Simulation ◽  
Morphological Changes ◽  
Dissociative Adsorption ◽  
Atomistic Simulations ◽  
Surface Energies ◽  
Simulation Techniques ◽  
Surface Configuration ◽  
Adsorption Of Water ◽  
Surface Hydroxylation ◽  
Glass Polishing

AbstractAtomistic simulation techniques have been used to investigate the dissociative adsorption of water on the (110), (111), and (100) low index surfaces of CeO2, as well as a so-called “trench” surface configuration. Several different coverages of water have been considered to better understand how the hydroxylation process progresses. Hydroxylation energies and surface energies of CeO2 calculated via atomistic simulations are compared to similar results for other fluorite oxides. Finally, the modification of CeO2 crystallite morphology in the presence of water is predicted from the changes in surface energy and the implications of these morphological changes for glass polishing are discussed.

Atomistic Simulation of the Dissociative Adsorption of Water on Calcite Surfaces

2003 ◽  
Vol 107 (31) ◽  
pp. 7676-7682 ◽  
Author(s):  
Sebastien Kerisit ◽  
Stephen C. Parker ◽  
John H. Harding
Keyword(s):  
Atomistic Simulation ◽  
Dissociative Adsorption ◽  
Adsorption Of Water

Analysis of Oxygen Vacancy Trapping at [001] Symmetric Tilt Grain Boundaries in Barium Titanate by Atomistic Simulations

2010 ◽  
Vol 445 ◽  
pp. 39-42 ◽  
Author(s):  
Takashi Oyama ◽  
Nobuyuki Wada ◽  
Hiroshi Takagi
Keyword(s):  
Barium Titanate ◽  
Grain Boundaries ◽  
Atomistic Simulation ◽  
Oxygen Vacancies ◽  
Atomistic Simulations ◽  
Multilayer Ceramic Capacitors ◽  
Simulation Techniques ◽  
Electrical Degradation ◽  
Symmetric Tilt

The role of grain boundaries (GBs) in the diffusion of oxygen vacancies (VO••s) in barium titanate (BaTiO3) and its mechanism were investigated using atomistic simulation techniques. It was found that GBs trapped VO••s at specific sites in the course of the diffusion, and the excess energy reflecting structural distortion of the GB was closely related to the availability of the trapping. GBs therefore act as a resistance of the diffusion of VO••s, suggesting that electrical degradation of multilayer ceramic capacitors (MLCCs), which is derived from vacancy diffusion, enables to be additionally improved by controlling GB structures in BaTiO3-based dielectrics.

scholarly journals Atomistic Simulations of the Defect Chemistry and Self-Diffusion of Li-ion in LiAlO2

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2895 ◽  
Author(s):  
N. Kuganathan ◽  
J. Dark ◽  
E.N. Sgourou ◽  
Y. Panayiotatos ◽  
A. Chroneos
Keyword(s):  
Atomistic Simulation ◽  
Three Dimensional ◽  
Atomistic Simulations ◽  
Intrinsic Defect ◽  
Lithium Content ◽  
Frenkel Defect ◽  
Self Diffusion ◽  
Simulation Techniques ◽  
Lithium Diffusion ◽  
Li Ion

Lithium aluminate, LiAlO2, is a material that is presently being considered as a tritium breeder material in fusion reactors and coating material in Li-conducting electrodes. Here, we employ atomistic simulation techniques to show that the lowest energy intrinsic defect process is the cation anti-site defect (1.10 eV per defect). This was followed closely by the lithium Frenkel defect (1.44 eV per defect), which ensures a high lithium content in the material and inclination for lithium diffusion from formation of vacancies. Li self-diffusion is three dimensional and exhibits a curved pathway with a migration barrier of 0.53 eV. We considered a variety of dopants with charges +1 (Na, K and Rb), +2 (Mg, Ca, Sr and Ba), +3 (Ga, Fe, Co, Ni, Mn, Sc, Y and La) and +4 (Si, Ge, Ti, Zr and Ce) on the Al site. Dopants Mg2+ and Ge4+ can facilitate the formation of Li interstitials and Li vacancies, respectively. Trivalent dopants Fe3+, Ni3+ and Mn3+ prefer to occupy the Al site with exoergic solution energies meaning that they are candidate dopants for the synthesis of Li (Al, M) O2 (M = Fe, Ni and Mn) compounds.

Atomistic Simulations of the (1014) Surface of Carbonate Minerals

2000 ◽  
Vol 620 ◽  
Author(s):  
Kate Wright ◽  
Randall T. Cygan ◽  
Ben Slater
Keyword(s):  
Atomistic Simulation ◽  
Atomistic Simulations ◽  
Simulation Methods ◽  
Carbonate Group ◽  
Surface Energies ◽  
Influence Of Water ◽  
Dry And Wet Conditions ◽  
Potential Parameters ◽  
Water Species ◽  
Monolayer Coverage

ABSTRACTAtomistic simulation methods have been used to model the structure of the (1014) surfaces of calcite, dolomite, and magnesite under dry and wet conditions. The potential parameters for the carbonate and water species contain shell terms to model the polarizability of the oxygen atoms. These static calculations show that the surfaces undergo relaxation leading to the rotation and distortion of the carbonate groups with associated movement of cations. The dry surface energies are 0.322, 0.247, and 0.256 Jm−2 for calcite, dolomite, and magnesite respectively. The influence of water on the surface structure and energies has been investigated for monolayer coverage. When fully hydrated with a monolayer of water, the surface energy for calcite is reduced indicating a stabilization of the surface with hydration. The extent of carbonate group distortion is greater for the dry surfaces compared to the hydrated surfaces, and for the dry calcite relative to that for dry magnesite.

A Perspective on Modeling Materials in Extreme Environments: Oxidation of Ultrahigh-Temperature Ceramics

MRS Bulletin ◽  
2006 ◽  
Vol 31 (5) ◽  
pp. 410-418 ◽  
Author(s):  
Angelo Bongiorno ◽  
Clemens J. Först ◽  
Rajiv K. Kalia ◽  
Ju Li ◽  
Jochen Marschall ◽  
...  
Keyword(s):  
Modeling And Simulation ◽  
Atomistic Simulation ◽  
Extreme Environments ◽  
Protective Layer ◽  
Ceramic Composites ◽  
Atomistic Modeling ◽  
Temperature Oxidation ◽  
Simulation Techniques ◽  
Oxidation Resistant ◽  
Ultrahigh Temperature

AbstractThe broader context of this discussion, based on a workshop where materials technologists and computational scientists engaged in a dialogue, is an awareness that modeling and simulation techniques and computational capabilities may have matured sufficiently to provide heretofore unavailable insights into the complex microstructural evolution of materials in extreme environments.As an example, this article examines the study of ultrahigh-temperature oxidation-resistant ceramics, through the combination of atomistic simulation and selected experiments.We describe a strategy to investigate oxygen transport through a multi-oxide scale—the protective layer of ultrahigh-temperature ceramic composites ZrB2-SiC and HfB2-SiC—by combining first-principles and atomistic modeling and simulation with selected experiments.

Structure Characteristics of TiO2 Thin Films Prepared by DC Reactive Magnetron Sputtering at Low Pressure

2021 ◽  
Vol 19 (4) ◽  
pp. 77-86
Author(s):  
A.S. Ahmed ◽  
I.H. Kadim ◽  
A.A. Ramadhan
Keyword(s):  
Thin Films ◽  
Total Pressure ◽  
Great Influence ◽  
Dissociative Adsorption ◽  
Interplanar Distance ◽  
Main Role ◽  
Tio2 Thin Films ◽  
Two Phase ◽  
Adsorption Of Water ◽  
Standard Value

Structural properties of TiO2 thin films play a main role in determine the characteristic of the thin films especially their stability and activity, the total pressure has a great influence in determine the crystallinity of the films and the orientation of the facets of their structure, especially the two facet (101) and (001), the enhancing the structure properties will cause to enhance the application efficiency of TiO2 thin films such as the dissociative adsorption of water and the solar cell. Many researcher interest to prepare the TiO2 thin film under the low range of total pressure (less than to 10 Pa) to avoid the low degree of crystalline and the mixed of two phase anatas and rutile, so in our work tend to prepare TiO2 thin films under a high total pressure (more than 10 Pa) with values (10, 20, 50 and 100) Pa and with (1:1) mixed ratio of Argon and Oxygen gases, the pattern of X-Ray diffraction revealed that the structure was polycrystalline and the phase was anatas. The intensity at 2θ ≈ 25.00°, 37.00°, 53.00° and 55.00° correspond to the diffraction from (101), (004), (105) and (211) planes respectively. The intensity and number of peaks decreased with increased the total pressure, the plane (101) could be considered as a prefential growth plane which take a high texture factor and this would decreased with increased the total pressure, the ratio of texture factor between 001 and 101 will increase with decrease the total pressure, The lattice constant and the interplanar distance displayed a greater deviation compared with the standard value at the lowest total pressure than the decrease observed with increased total pressure.

Role of Steps in the Dissociative Adsorption of Water on RutileTiO2(110)

2013 ◽  
Vol 110 (14) ◽  
Author(s):  
H. H. Kristoffersen ◽  
J. Ø. Hansen ◽  
U. Martinez ◽  
Y. Y. Wei ◽  
J. Matthiesen ◽  
...  
Keyword(s):  
Dissociative Adsorption ◽  
Adsorption Of Water
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