Band engineering via grain boundary defect states for large scale tuning of photoconductivity in Bi1−xCaxFe1−yTiyO3−δ

2019 ◽  
Vol 126 (23) ◽  
pp. 235101
Author(s):  
Subhajit Nandy ◽  
Pavana S. V. Mocherla ◽  
Kulwinder Kaur ◽  
Sanjeev Gautam ◽  
B. R. K. Nanda ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Large Scale ◽  
Defect States ◽  
Band Engineering ◽  
Boundary Defect

scholarly journals Elucidating the Onset of Plasticity in Sliding Contacts Using Differential Computational Orientation Tomography

2021 ◽  
Vol 69 (3) ◽  
Author(s):  
S. J. Eder ◽  
P. G. Grützmacher ◽  
M. Rodríguez Ripoll ◽  
J. F. Belak
Keyword(s):  
Grain Boundary ◽  
Large Scale ◽  
Surface Deformation ◽  
Boundary Migration ◽  
Material Design ◽  
Lattice Rotation ◽  
Time Resolved ◽  
Near Surface ◽  
Color Saturation ◽  
Dynamics Simulations

Abstract Depending on the mechanical and thermal energy introduced to a dry sliding interface, the near-surface regions of the mated bodies may undergo plastic deformation. In this work, we use large-scale molecular dynamics simulations to generate “differential computational orientation tomographs” (dCOT) and thus highlight changes to the microstructure near tribological FCC alloy surfaces, allowing us to detect subtle differences in lattice orientation and small distances in grain boundary migration. The analysis approach compares computationally generated orientation tomographs with their undeformed counterparts via a simple image analysis filter. We use our visualization method to discuss the acting microstructural mechanisms in a load- and time-resolved fashion, focusing on sliding conditions that lead to twinning, partial lattice rotation, and grain boundary-dominated processes. Extracting and laterally averaging the color saturation value of the generated tomographs allows us to produce quantitative time- and depth-resolved maps that give a good overview of the progress and severity of near-surface deformation. Corresponding maps of the lateral standard deviation in the color saturation show evidence of homogenization processes occurring in the tribologically loaded microstructure, frequently leading to the formation of a well-defined separation between deformed and undeformed regions. When integrated into a computational materials engineering framework, our approach could help optimize material design for tribological and other deformation problems. Graphic Abstract .

Spatially resolved investigation of the defect states in methylammonium lead iodide perovskite bicrystals

2019 ◽  
Vol 7 (42) ◽  
pp. 13156-13160 ◽  
Author(s):  
Svetlana Sirotinskaya ◽  
Christian Fettkenhauer ◽  
Daichi Okada ◽  
Yohei Yamamoto ◽  
Doru C. Lupascu ◽  
...  
Keyword(s):  
Thin Film ◽  
Grain Boundary ◽  
System Approach ◽  
Defect States ◽  
Lead Iodide ◽  
Modal System ◽  
Trap Formation ◽  
Spatially Resolved ◽  
Methylammonium Lead Iodide

Introducing a modal system approach for the analytical perovskite thin-film trap physics evaluation. Our study confirms existing models for trap formation in MAPI, substantiating different defect states in the grain boundary and bulk regions.

Grain boundary defect compensation in Ti-doped BaFe0.5Nb0.5O3 ceramics

2016 ◽  
Vol 122 (9) ◽  
Author(s):  
Xiaojun Sun ◽  
Jianming Deng ◽  
Saisai Liu ◽  
Tianxiang Yan ◽  
Biaolin Peng ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Boundary Defect

Atomistic and Continuum Studies of Diffusional Creep and Associated Dislocation Mechanisms in thin Films on Substrates

2003 ◽  
Vol 779 ◽  
Author(s):  
Markus J. Buehler ◽  
Alexander Hartmaier ◽  
Huajian Gao
Keyword(s):  
Thin Films ◽  
Stress Field ◽  
Grain Boundary ◽  
Large Scale ◽  
Strain Relaxation ◽  
Dislocation Dynamics ◽  
Biaxial Stress ◽  
Diffusional Creep ◽  
Material Transport ◽  
Dynamics Simulations

AbstractMotivated by recent theoretical and experimental progress, large-scale atomistic simulations are performed to study plastic deformation in sub-micron thin films. The studies reveal that stresses are relaxed by material transport from the surface into the grain boundary. This leads to the formation of a novel defect identified as diffusion wedge. Eventually, a crack-like stress field develops because the tractions along the grain boundary relax, but the adhesion of the film to the substrate prohibits strain relaxation close to the interface. This causes nucleation of unexpected parallel glide dislocations at the grain boundary-substrate interface, for which no driving force exists in the overall biaxial stress field. The observation of parallel glide dislocations in molecular dynamics studies closes the theory-experiment-simulation linkage. In this study, we also compare the nucleation of dislocations from a diffusion wedge with nucleation from a crack. Further, we present preliminary results of modeling constrained diffusional creep using discrete dislocation dynamics simulations.

scholarly journals Deformation Behavior of Nanocrystalline Body-Centered Cubic Iron with Segregated, Foreign Interstitial: A Molecular Dynamics Study

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5351
Author(s):  
Ahmed Tamer AlMotasem ◽  
Matthias Posselt ◽  
Tomas Polcar
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Deformation Behavior ◽  
Large Scale ◽  
Grain Boundary Sliding ◽  
Carbon And Nitrogen ◽  
Embedded Atom ◽  
Boundary Sliding ◽  
Dynamics Simulations

In the present work, modified embedded atom potential and large-scale molecular dynamics’ simulations were used to explore the effect of grain boundary (GB) segregated foreign interstitials on the deformation behavior of nanocrystalline (nc) iron. As a case study, carbon and nitrogen (about 2.5 at.%) were added to (nc) iron. The tensile test results showed that, at the onset of plasticity, grain boundary sliding mediated was dominated, whereas both dislocations and twinning were prevailing deformation mechanisms at high strain. Adding C/N into GBs reduces the free excess volume and consequently increases resistance to GB sliding. In agreement with experiments, the flow stress increased due to the presence of carbon or nitrogen and carbon had the stronger impact. Additionally, the simulation results revealed that GB reduction and suppressing GBs’ dislocation were the primary cause for GB strengthening. Moreover, we also found that the stress required for both intragranular dislocation and twinning nucleation were strongly dependent on the solute type.

Interlaced Pd–Ag nanowires rich in grain boundary defects for boosting oxygen reduction electrocatalysis

Nanoscale ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 5368-5373 ◽  
Author(s):  
Xiao-Jing Liu ◽  
Xing Yin ◽  
Yi-Dan Sun ◽  
Feng-Jiao Yu ◽  
Xiang-Wen Gao ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
Defect Engineering ◽  
Boundary Defect ◽  
Enhanced Activity ◽  
Ag Nanowires

Pd–Ag interlaced nanowires with grain boundary defect engineering exhibit enhanced activity and superior stability for oxygen reduction reaction in alkaline media.

scholarly journals Grain Boundary Motion under Dynamic Loading: Mechanism and Large-Scale Molecular Dynamics Simulations

2013 ◽  
Vol 1 (4) ◽  
pp. 220-227 ◽  
Author(s):  
Christian Brandl ◽  
Timothy C. Germann ◽  
Alejandro G. Perez-Bergquist ◽  
Ellen K. Cerreta
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Molecular Dynamics Simulations ◽  
Dynamic Loading ◽  
Large Scale ◽  
Boundary Motion ◽  
Dynamics Simulations ◽  
Grain Boundary Motion
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