scholarly journals Theoretical Modeling of Defects, Dopants, and Diffusion in the Mineral Ilmenite

Minerals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 610 ◽  
Author(s):  
Kuganathan ◽  
Srikaran ◽  
Fossati ◽  
Chroneos
Keyword(s):  
Atomistic Simulation ◽  
Ion Diffusion ◽  
Spintronic Devices ◽  
Solution Enthalpy ◽  
Pair Potentials ◽  
Simulation Techniques ◽  
Industrial Preparation ◽  
Fast Ion ◽  
Extrinsic Defects ◽  
And Diffusion

The iron titanium oxide ilmenite (FeTiO3) is a technologically and economically important mineral in the industrial preparation of titanium-based pigments and spintronic devices. In this study, atomistic simulation techniques based on classical pair potentials are used to examine the energetics of the intrinsic and extrinsic defects and diffusion of Fe2+ ions in FeTiO3. It is calculated that the cation anti-site (Fe‒Ti) cluster is the most dominant defect, suggesting that a small amount of cations exchange their positions, forming a disordered structure. The formation of Fe Frenkel is highly endoergic and calculated to be the second most stable defect process. The Fe2+ ions migrate in the ab plane with the activation energy of 0.52 eV, inferring fast ion diffusion. Mn2+ and Ge4+ ions are found to be the prominent isovalent dopants at the Fe and Ti site, respectively. The formation of additional Fe2+ ions and O vacancies was considered by substituting trivalent dopants (Al3+, Mn3+, Ga3+, Sc3+, In3+, Yb3+, Y3+, Ga3+, and La3+) at the Ti site. Though Ga3+ is found to be the candidate dopant, its solution enthalpy is >3 eV, suggesting that the formation is not significant at operating temperatures.

scholarly journals Defect, Diffusion and Dopant Properties of NaNiO2: Atomistic Simulation Study

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3094 ◽  
Author(s):  
Ruwani Kaushalya ◽  
Poobalasuntharam Iyngaran ◽  
Navaratnarajah Kuganathan ◽  
Alexander Chroneos
Keyword(s):  
Atomistic Simulation ◽  
High Capacity ◽  
Sodium Ion ◽  
Intrinsic Defect ◽  
Sodium Ion Batteries ◽  
Ion Diffusion ◽  
Defect Diffusion ◽  
Simulation Techniques ◽  
Defect Process ◽  
Isovalent Dopant

Sodium nickelate, NaNiO2, is a candidate cathode material for sodium ion batteries due to its high volumetric and gravimetric energy density. The use of atomistic simulation techniques allows the examination of the defect energetics, Na-ion diffusion and dopant properties within the crystal. Here, we show that the lowest energy intrinsic defect process is the Na-Ni anti-site. The Na Frenkel, which introduces Na vacancies in the lattice, is found to be the second most favourable defect process and this process is higher in energy only by 0.16 eV than the anti-site defect. Favourable Na-ion diffusion barrier of 0.67 eV in the ab plane indicates that the Na-ion diffusion in this material is relatively fast. Favourable divalent dopant on the Ni site is Co2+ that increases additional Na, leading to high capacity. The formation of Na vacancies can be facilitated by doping Ti4+ on the Ni site. The promising isovalent dopant on the Ni site is Ga3+.

scholarly journals Structural and Defect Properties of LiTi2(PO4)3

2021 ◽  
Vol 11 (5) ◽  
pp. 13268-13275
Keyword(s):  
Atomistic Simulation ◽  
Three Dimensional ◽  
Intrinsic Defect ◽  
Ion Diffusion ◽  
Ion Migration ◽  
Pair Potentials ◽  
Simulation Based ◽  
Engineering Strategy ◽  
Li Ion ◽  
High Chemical Stability

LiTi2(PO4)3 is an attractive electrolyte material in Li-ion batteries' application due to its high ionic conductivity and high chemical stability. Here we employ atomistic simulation based on the classical pair potentials to examine the intrinsic defect processes, Li-ion migration, and solution of various dopants in LiTi2(PO4)3. The Li-Frenkel (0.73 eV) is calculated to be the most favorable defect energy process ensuring the formation of Li vacancies required for the vacancy-assisted Li-ion migration. Long-range three-dimensional lithium vacancy migration was observed with a low activation energy of 0.36 eV, inferring fast Li-ion diffusion. The most favorable isovalent dopants on the Li and Ti sites are Na and Si, respectively. Li interstitials' formation in these materials is favored by doping of Ga on the Ti site. This engineering strategy can be of interest to improve the capacity of LiTi2(PO4)3.

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.

T-Nb2O5 nanoparticles confined in carbon nanotubes with fast ion diffusion rate for lithium storage

2021 ◽  
Author(s):  
Yang Zhang ◽  
Yakun Tang ◽  
Lang Liu ◽  
Yue Zhang ◽  
Zhiguo Li
Keyword(s):  
Carbon Nanotubes ◽  
Active Sites ◽  
Diffusion Rate ◽  
Conductive Network ◽  
Ion Diffusion ◽  
Lithium Storage ◽  
Transmission Path ◽  
Fast Ion

T-Nb2O5/CNT nanohybrid with short transmission path, rich active sites, and favorable mechanical flexibility can achieve the fast transportation of ions/electrons. The obtained nanohybrid with continuous conductive network exhibit better lithium...

scholarly journals Doping-template approach of porous-walled graphitic nanocages for superior performance anodes of lithium ion batteries

RSC Advances ◽  
2017 ◽  
Vol 7 (67) ◽  
pp. 42083-42087 ◽  
Author(s):  
Zhao Min Sheng ◽  
Xin Jian Chang ◽  
Yu Hang Chen ◽  
Cheng Yang Hong ◽  
Na Na Li ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Lithium Ion ◽  
Superior Performance ◽  
Ion Diffusion ◽  
Fast Ion ◽  
P Removal

Removal of the N-doped template creates nanopores in the shells of nanocages. The created nanopores enhance fast ion diffusion.

Three-dimensional graphene oxide/polypyrrole composite electrodes fabricated by one-step electrodeposition for high performance supercapacitors

2015 ◽  
Vol 3 (27) ◽  
pp. 14445-14457 ◽  
Author(s):  
Jianyun Cao ◽  
Yaming Wang ◽  
Junchen Chen ◽  
Xiaohong Li ◽  
Frank C. Walsh ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
High Performance ◽  
Three Dimensional ◽  
Composite Electrodes ◽  
Ion Diffusion ◽  
One Step ◽  
Supercapacitor Performance ◽  
Polypyrrole Composite ◽  
Fast Ion ◽  
Interconnected Structure

The 3D interconnected structure of the GO/PPy composite ensures fast ion diffusion through the electrode, leading to excellent supercapacitor performance.

scholarly journals Atomistic Simulation of Intrinsic Defects and Trivalent and Tetravalent Ion Doping in Hydroxyapatite

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Ricardo D. S. Santos ◽  
Marcos V. dos S. Rezende
Keyword(s):  
Atomistic Simulation ◽  
Charge Compensation ◽  
Intrinsic Defect ◽  
Intrinsic Defects ◽  
Simulation Techniques ◽  
Ion Doping ◽  
Key Issues

Atomistic simulation techniques have been employed in order to investigate key issues related to intrinsic defects and a variety of dopants from trivalent and tetravalent ions. The most favorable intrinsic defect is determined to be a scheme involving calcium and hydroxyl vacancies. It is found that trivalent ions have an energetic preference for the Ca site, while tetravalent ions can enter P sites. Charge compensation is predicted to occur basically via three schemes. In general, the charge compensation via the formation of calcium vacancies is more favorable. Trivalent dopant ions are more stable than tetravalent dopants.

scholarly journals Ultrathin two-dimensional conjugated metal–organic framework single-crystalline nanosheets enabled by surfactant-assisted synthesis

2020 ◽  
Vol 11 (29) ◽  
pp. 7665-7671 ◽  
Author(s):  
Zhiyong Wang ◽  
Gang Wang ◽  
Haoyuan Qi ◽  
Mao Wang ◽  
Mingchao Wang ◽  
...  
Keyword(s):  
Active Sites ◽  
Metal Organic Framework ◽  
Li Ion Batteries ◽  
Ion Diffusion ◽  
Single Crystalline ◽  
Metal Organic ◽  
Li Ion ◽  
High Utilization ◽  
Fast Ion ◽  
Surfactant Assisted

Ultrathin and large-sized 2D conjugated MOF single-crystalline nanosheets are synthesized, which allow fast ion diffusion and high utilization of active sites, and therefore exhibit remarkable performance for Li-ion batteries.

scholarly journals Defects, Diffusion and Dopants in Sillimanite

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 857
Author(s):  
Raveena Sukumar ◽  
Poobalasuntharam Iyngaran ◽  
Navaratnarajah Kuganathan ◽  
Alexander Chroneos
Keyword(s):  
Pair Potential ◽  
Chemical Properties ◽  
Activation Energies ◽  
Aluminum Silicate ◽  
Intrinsic Defect ◽  
Ion Diffusion ◽  
Silicon Alloys ◽  
Aluminum Silicon Alloys ◽  
Cation Disorder ◽  
Industrial Preparation

Aluminum silicate based mineral “Sillimanite” (Al2SiO5) is important in the industrial preparation of aluminum-silicon alloys and cement. In the present study classical pair potential simulations are used to examine the intrinsic defect processes, diffusion pathways of Al3+ and O2− ions together with their activation energies and promising dopants on the Al and Si sites in Al2SiO5. The cation anti-site (Al-Si) defect cluster is calculated to be the most favorable defect, highlighting the cation disorder in this material, in agreement with the experiment. The cation disorder is important as this defect can change the mechanical and chemical properties of Al2SiO5. The Al3+ ions and O2− ions migrate in the c direction with corresponding activation energies of 2.26 eV and 2.75 eV inferring slow ion diffusion. The prominent isovalent dopants on the Al and Si sites are found to be the Ga and Ge, respectively, suggesting that they can be used to prevent phase transformation and tune the properties of sillimanite.

Ultrathin oxide films: CaO layers on BaO and SrO

2008 ◽  
Vol 1148 ◽  
Author(s):  
Chris E Mohn ◽  
Neil L. Allan ◽  
John H. Harding
Keyword(s):  
Density Functional Theory ◽  
Atomistic Simulation ◽  
Density Functional ◽  
Functional Theory ◽  
Bond Lengths ◽  
Simulation Techniques ◽  
Ultrathin Oxide Films ◽  
Anion Separation ◽  
Crystalline Oxides ◽  
Ultrathin Oxide

AbstractPrompted by renewed interest in the crystalline oxides-on-semiconductors interface, periodic density functional theory and atomistic simulation techniques are used to examine the formation of a layer of CaO on a BaO substrate. We examine how CaO islands which form at coverages less than 100% adjust to the substrate in which the cation-anion separation is substantially larger than in CaO itself. All Ca-O bond lengths in the island are shorter than that in bulk CaO. Corner O atoms in the islands are associated with particularly short Ca-O bond lengths, and the shape of the islands is dominated by (100) edges. Once formed, islands with intact edges will remain intact. Interactions between islands at larger coverages are also investigated and we see the formation of characteristic elliptical gaps and loops.

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