scholarly journals The effect of defect interactions on the reduction of doped ceria

2021 ◽  
Author(s):  
Steffen Grieshammer
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
First Principles ◽  
Doped Ceria ◽  
Reduction Behavior ◽  
Multi Stage ◽  
Defect Interactions

Multi-stage Monte Carlo simulations are applied to predict the non-ideal reduction behavior of doped ceria based on first-principles energies.

scholarly journals The effect of ionic defect interactions on the hydration of yttrium-doped barium zirconate

2021 ◽  
Author(s):  
Sebastian Eisele ◽  
Fabian M. Draber ◽  
Steffen Grieshammer
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
First Principles ◽  
Barium Zirconate ◽  
First Principles Calculations ◽  
Defect Interactions ◽  
The Impact ◽  
Ionic Defect

First principles calculations and Monte Carlo simulations reveal the impact of defect interactions on the hydration of barium-zirconate.

scholarly journals Association of defects in doped non-stoichiometric ceria from first principles

2016 ◽  
Vol 18 (5) ◽  
pp. 3804-3811 ◽  
Author(s):  
Steffen Grieshammer ◽  
Masanobu Nakayama ◽  
Manfred Martin
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
First Principles ◽  
Doped Ceria ◽  
Defect Interaction

DFT+U and Monte Carlo simulations reveal that defect interaction in doped ceria leads to a decrease of the energy of reduction.

Understanding the ionic conductivity maximum in doped ceria: trapping and blocking

2018 ◽  
Vol 20 (21) ◽  
pp. 14291-14321 ◽  
Author(s):  
Julius Koettgen ◽  
Steffen Grieshammer ◽  
Philipp Hein ◽  
Benjamin O. H. Grope ◽  
Masanobu Nakayama ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Ionic Conductivity ◽  
Dft Calculations ◽  
Monte Carlo Simulations ◽  
First Principles ◽  
Kinetic Monte Carlo ◽  
Doped Ceria ◽  
Kinetic Monte Carlo Simulations

Ionic conductivity is systematically predicted by only a few migration energies from first-principles DFT calculations combined with Kinetic Monte Carlo simulations.

scholarly journals Structural Transition of Vacancy-Solute Complexes in Al-Mg-Si Alloys

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 2
Author(s):  
Masataka Mizuno ◽  
Kazuki Sugita ◽  
Hideki Araki
Keyword(s):  
Solid Solution ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
First Principles ◽  
Structural Transition ◽  
First Principles Calculations ◽  
Eye Formation

To theoretically examine the structural transition of vacancy–solute complexes in Al–Mg–Si alloys, we performed first-principles calculations for layered vacancy–solute complexes with additional Mg atoms. The central Mg atom in the additional Mg layer shifted to the Si layer with the increase in the number of Mg atoms to weaken the repulsive Mg–Mg interaction and to form Mg–Si bonds. When five Mg atoms were added to the layered vacancy–solute complex, the central Mg atom completely shifted to the Si layer, and a Mg vacancy was formed in the Mg layer, which indicated that the β″-eye is formed upon the addition of Mg atoms. We reproduced β″-eye formation from a solid solution with a vacancy using first-principles-based Monte Carlo simulations. Once the β″-eye was formed on the layered vacancy–solute complex, the process can be repeated by the formation of alternate Mg and Si layers along [010] β″. These results clearly indicate that the layered vacancy–solute complex plays an important role in β″-eye formation.

scholarly journals Anion order in perovskite oxynitrides AMO2N (A = Ba, Sr, Ca; M = Ta, Nb): a first-principles based investigation

RSC Advances ◽  
2020 ◽  
Vol 10 (41) ◽  
pp. 24410-24418
Author(s):  
Xi Xu ◽  
Hong Jiang
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Cluster Expansion ◽  
First Principles ◽  
Expansion Method ◽  
First Principles Calculations ◽  
Cluster Expansion Method

Anion order in perovskite oxynitrides is investigated by a combination of first-principles calculations, cluster expansion method and Monte Carlo simulations.

Kinetic Monte Carlo Simulations for Solid State Ionics: Case Studies with the MOCASSIN Program

2021 ◽  
Vol 29 ◽  
pp. 117-142
Author(s):  
Steffen Grieshammer ◽  
Sebastian Eisele
Keyword(s):  
Monte Carlo ◽  
Solid State ◽  
Ionic Conductivity ◽  
Monte Carlo Simulations ◽  
Kinetic Monte Carlo ◽  
Model Systems ◽  
Solid State Ionics ◽  
Kinetic Monte Carlo Simulations ◽  
Defect Interactions ◽  
The Impact

Kinetic Monte Carlo simulations are a useful tool to predict and analyze the ionic conductivity in crystalline materials. We present here the basic functionalities and capabilities of our recently published Monte Carlo software for solid state ionics called MOCASSIN, exemplified by simulations of several model systems and real materials. We address the simulation of tracer correlation factors for various structures, the correlation in systems with complex migration mechanisms like interstitialcy or vehicle transport, and the impact of defect interactions on ionic conductivity. Simulations of real materials include a review of oxygen vacancy migration in doped ceria, oxygen interstitial migration in La-rich melilites, and proton conduction in acceptor doped fully hydrated barium zirconate. The results reveal the impact of defect interactions on the ionic conductivity and the importance of the defect distribution. Combinations of these effects can lead to unexpected transport behavior in solid state ionic materials, especially for multiple mobile species. Kinetic Monte Carlo simulations are therefore useful to interpret experimental data which shows unexpected behavior regarding the dependence on temperature and composition.

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