Cation ordering and oxygen transport behaviour in Sr1−3x/2LaxTiO3perovskites

2017 ◽  
Vol 5 (11) ◽  
pp. 5321-5331 ◽  
Author(s):  
Paul C. M. Fossati ◽  
Robin W. Grimes
Keyword(s):  
Oxygen Transport ◽  
Oxygen Diffusion ◽  
Cation Ordering ◽  
Atomistic Modelling ◽  
Modelling Techniques ◽  
Transport Behaviour ◽  
Diffusion Mechanisms

Effects of cation ordering on oxygen diffusion mechanisms in (Sr,La)TiO3perovskites is investigated using atomistic modelling techniques.

scholarly journals New insights into microstructure of irradiated beryllium based on experiments and computer simulations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
M. Klimenkov ◽  
P. Vladimirov ◽  
U. Jäntsch ◽  
V. Kuksenko ◽  
R. Rolli ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Gas Bubbles ◽  
Atomic Scale ◽  
Average Height ◽  
Secondary Phases ◽  
Atomistic Modelling ◽  
Transmission Electron ◽  
Intermetallic Precipitates ◽  
Diffusion Mechanisms ◽  
Small Bubbles

Abstract The microstructural response of beryllium after neutron irradiation at various temperatures (643–923 K) was systematically studied using analytical transmission electron microscope that together with outcomes from advanced atomistic modelling provides new insights in the mechanisms of microstructural changes in this material. The most prominent feature of microstructural modification is the formation of gas bubbles, which is revealed at all studied irradiation temperatures. Except for the lowest irradiation temperature, gas bubbles have the shape of thin hexagonal prisms with average height and diameter increasing with temperature. A high number density of small bubbles is observed within grains, while significantly larger bubbles are formed along high-angle grain boundaries (GB). Denuded zones (DZ) nearly free from bubbles are found along both high- and low-angle grain boundaries. Precipitations of secondary phases (mainly intermetallic Al-Fe-Be) were observed inside grains, along dislocation lines and at GBs. EDX analysis has revealed homogeneous segregation of chromium and iron along GBs. The observed features are discussed with respect to the available atomistic modelling results. In particular, we present a plausible reasoning for the abundant formation of gas bubbles on intermetallic precipitates, observation of various thickness of zones denuded in gas bubbles and precipitates, and their relation to the atomic scale diffusion mechanisms of solute-vacancy clusters.

scholarly journals The effect of sub-surface strontium depletion on oxygen diffusion in La0.6Sr0.4Co0.2Fe0.8O3−δ

2020 ◽  
Vol 8 (37) ◽  
pp. 19414-19424 ◽  
Author(s):  
Mathew A. R. Niania ◽  
Andrew K. Rossall ◽  
Jaap A. Van den Berg ◽  
John A. Kilner
Keyword(s):  
Transport Properties ◽  
Oxygen Transport ◽  
Oxygen Diffusion ◽  
Surface Composition ◽  
Ion Beam ◽  
Ion Beam Analysis ◽  
Heat Treated ◽  
Beam Analysis ◽  
Depth Scale

The immediate surface and sub-surface composition of heat treated La0.6Sr0.4Co0.2Fe0.8O3−δ samples was measured by ion beam analysis and compared to oxygen transport properties over the same depth scale.

Further development of large-scale atomistic modelling techniques for Fe–Cr alloys

2011 ◽  
Vol 409 (2) ◽  
pp. 167-175 ◽  
Author(s):  
D. Terentyev ◽  
G. Bonny ◽  
N. Castin ◽  
C. Domain ◽  
L. Malerba ◽  
...  
Keyword(s):  
Large Scale ◽  
Atomistic Modelling ◽  
Modelling Techniques ◽  
Further Development

scholarly journals Achieving fast oxygen diffusion in perovskites by cation ordering

2005 ◽  
Vol 86 (9) ◽  
pp. 091910 ◽  
Author(s):  
A. A. Taskin ◽  
A. N. Lavrov ◽  
Yoichi Ando
Keyword(s):  
Oxygen Diffusion ◽  
Cation Ordering

Theoretical Modelling of Nuclear Waste Flows

2009 ◽  
Author(s):  
J. F. Adams ◽  
S. R. Biggs ◽  
M. Fairweather ◽  
D. Njobuenwu ◽  
J. Yao
Keyword(s):  
Particle Size ◽  
Nuclear Waste ◽  
Process Design ◽  
Cost Effective ◽  
Particle Dispersion ◽  
Waste Processing ◽  
Square Duct ◽  
Modelling Techniques ◽  
Transport Behaviour ◽  
Good Agreement

A large amount of nuclear waste is stored in tailings ponds as a solid-liquid slurry, and liquid flows containing suspensions of solid particles are encountered in the treatment and disposal of this waste. In processing this waste, it is important to understand the behaviour of particles within the flow in terms of their settling characteristics, their propensity to form solid beds, and the re-suspension characteristics of particles from a bed. A clearer understanding of such behaviour would allow the refinement of current approaches to waste management, potentially leading to reduced uncertainties in radiological impact assessments, smaller waste volumes and lower costs, accelerated clean-up, reduced worker doses, enhanced public confidence and diminished grounds for objection to waste disposal. Mathematical models are of significant value in nuclear waste processing since the extent of characterisation of wastes is in general low. Additionally, waste processing involves a diverse range of flows, within vessels, ponds and pipes. To investigate experimentally all waste form characteristics and potential flows of interest would be prohibitively expensive, whereas the use of mathematical models can help to focus experimental studies through the more efficient use of existing data, the identification of data requirements, and a reduction in the need for process optimisation in full-scale experimental trials. Validated models can also be used to predict waste transport behaviour to enable cost effective process design and continued operation, to provide input to process selection, and to allow the prediction of operational boundaries that account for the different types and compositions of particulate wastes. In this paper two mathematical modelling techniques, namely Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES), have been used to investigate particle-laden flows in a straight square duct and a duct with a bend. The flow solutions provided by these methods have been coupled to a three-dimensional Lagrangian particle tracking routine to predict particle trajectories. Simulation results are shown to be good agreement with experimental data, where available. Based on the LES and RANS-Lagrangian methods, the mean value of the particle displacement in a straight square duct is found to generally decrease with time due to gravity effects, with the rate of deposition increasing with particle size. Using the RANS-Lagrangian method to study flows in a duct bend, there is good agreement between predicted profiles and data, with the method able to simulate particle dispersion, the phenomenon of particle roping and the increase of particle collisions with the bend-wall with particle size. With the LES-Lagrangian method, particle re-suspension from a bed is studied in a straight square duct flow and this process shown to be dominated by secondary flows within the duct, with smaller particles tending to re-suspend in preference to larger ones. Overall, the study demonstrates that modelling techniques can be used to provide insight in to processes that are of relevance to the processing of nuclear waste, and are capable of predicting their transport behaviour. In particular, they are able to provide reliable predictions of particle deposition within flows to form solid beds, the re-suspension of particles from a bed, and the influence of complex flow geometries on particle dispersion. In the latter case, they are also of value to studies of erosion due to particle impact. Such models are therefore of value as engineering tools for use in the prediction of waste behaviour and in cost effective process design.

Aspects of Radiation Damage Effects in Iron-Chromium Alloys From the Point of View of Atomistic Modelling

2009 ◽  
Author(s):  
Dmitry Terentyev ◽  
Giovanni Bonny ◽  
Nicolas Castin
Keyword(s):  
Radiation Damage ◽  
Power Plants ◽  
Theoretical Models ◽  
Point Of View ◽  
Atomistic Modelling ◽  
Chromium Alloys ◽  
Modelling Techniques ◽  
Level Of Understanding ◽  
Near Future ◽  
Significant Effort

Fe-Cr alloys are the basis of high-Cr ferritic steels, which are the candidate structural materials for near future power plants. Recently, a significant effort has been put in the development of theoretical models dealing with the response of Fe-Cr alloys to irradiation. Here, we give a brief overview of the current level of understanding of radiation damage in Fe-Cr alloys, based on the most recent results. In particular, we review and summarize data obtained using different atomistic modelling techniques in order to refine the most important findings achieved over the past few years.

scholarly journals Low temperature oxygen diffusion mechanisms in Nd2NiO4+δ and Pr2NiO4+δvia large anharmonic displacements, explored by single crystal neutron diffraction

2015 ◽  
Vol 3 (42) ◽  
pp. 21140-21148 ◽  
Author(s):  
M. Ceretti ◽  
O. Wahyudi ◽  
A. Cousson ◽  
A. Villesuzanne ◽  
M. Meven ◽  
...  
Keyword(s):  
Low Temperature ◽  
Neutron Diffraction ◽  
Neutron Scattering ◽  
Single Crystal ◽  
Oxygen Diffusion ◽  
Apical Oxygen ◽  
Diffusion Pathway ◽  
Energy Diffusion ◽  
Diffusion Mechanisms ◽  
Oxygen Atoms

Quasi-continuous shallow energy diffusion pathway and anharmonic double potential of the apical oxygen atoms in Pr2NiO4.25 explored by single crystal neutron scattering at 400 °C.

Insights into the design of nineteen-channel perovskite hollow fiber membrane and its oxygen transport behaviour

2020 ◽  
Vol 595 ◽  
pp. 117600 ◽  
Author(s):  
Tianlei Wang ◽  
Zhengkun Liu ◽  
Xiaolong Xu ◽  
Jiawei Zhu ◽  
Guangru Zhang ◽  
...  
Keyword(s):  
Oxygen Transport ◽  
Hollow Fiber ◽  
Hollow Fiber Membrane ◽  
Fiber Membrane ◽  
Transport Behaviour
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