Understanding the chemistry of ceramic materials under irradiation
Lead Research Organisation:
Science and Technology Facilities Council
Department Name: Computational Science & Engineering
Abstract
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Publications
Archer A
(2020)
Multiple cascade radiation damage simulations of pyrochlore
in Molecular Simulation
Archer A
(2014)
Order parameter and connectivity topology analysis of crystalline ceramics for nuclear waste immobilization.
in Journal of physics. Condensed matter : an Institute of Physics journal
Gunn D
(2014)
Adaptive kinetic Monte Carlo simulation of solid oxide fuel cell components
in J. Mater. Chem. A
| Description | High-level radioactive waste needs to be contained for long periods of time. An important part of this is to incorporate the radioactive atoms into host materials that are artificial minerals. Inevitably, the atomic structure of these minerals will be disrupted by the radioactive decay of the atoms. The purpose of this work was to find new methods of describing this disruption and using these to investigate materials that can heal themselves after the disruption has occurred. We developed ways of describing this disruption based on local ordering and local topology that demonstrated that, despite the initial gross disorder of the damage cascade, the mineral does retain a memory of its original local order and self-healing occurs to a considerable extent. The new methods show that the initial highly disordered state is not molten (as has often been asserted). After the initial damage and healing, longer-term healing can take place by defects in the solids moving and annihilating each other. We have therefore developed a computer code (using an Adaptive kinetic Monte Carlo method) that can describe this longer-term healing. Unravelling the healing mechanisms has highlighted important differences between possible host materials, some of which will heal effectively and others less well. Such a code can also treat diffusion problems at much longer timescales than conventional simulations using molecular dynamics and is therefore of wide potential utility for simulations in ceramics. |
| Exploitation Route | The new methods of defect analysis can be used to describe radiation damage in all materials, whether ceramics or metals and will be particularly useful in characterising defect populations in the presence of high concentrations of defects where they cannot be considered as isolated species and where conventional methods defining defects in terms of the displacement of atoms from their original sites give misleading results. The adaptive kinetic Monte Carlo code is appropriate for a wide range of problems in the simulation of ceramics where it is necessary to simulate slow processes. This includes problems of sintering, creep, surface diffusion (as in catalysis). Further details of the code can be found in the website above. |
| Sectors | Digital/Communication/Information Technologies (including Software) |
| URL | http://www.ccp5.ac.uk/DL_AKMC |
| Description | What have you discovered or developed through the research funded on this grant? Please explain for a non-specialist audience. * High-level radioactive waste needs to be contained for long periods of time. An important part of this is to incorporate the radioactive atoms into host materials that are artificial minerals. Inevitably, the atomic structure of these minerals will be disrupted by the radioactive decay of the atoms. The purpose of this work was to find new methods of describing this disruption and using these to investigate materials that can heal themselves after the disruption has occurred. We developed ways of describing this disruption based on local ordering and local topology that demonstrated that, despite the initial gross disorder of the damage cascade, the mineral does retain a memory of its original local order and self-healing occurs to a considerable extent. The new methods show that the initial highly disordered state is not molten (as has often been asserted). After the initial damage and healing, longer-term healing can take place by defects in the solids moving and annihilating each other. We have therefore developed a computer code (using a kinetic Monte Carlo method) that can describe this longer-term healing. Unravelling the healing mechanisms has highlighted important differences between possible host materials, some of which will heal effectively and others less well. Such a code can also treat diffusion problems at much longer timescales than conventional simulations using molecular dynamics and is therefore of wide potential utility for simulations in ceramics. In what ways might your findings be taken forward or put to use by others? The new methods of defect analysis can be used to describe radiation damage in all materials, whether ceramics or metals and will be particularly useful in characterising defect populations in the presence of high concentrations of defects where they cannot be considered as isolated species and where conventional methods defining defects in terms of the displacement of atoms from their original sites give misleading results. The kinetic Monte Carlo code is appropriate for a wide range of problems in the simulation of ceramics where it is necessary to simulate slow processes. This includes problems of sintering, creep, surface diffusion (as in catalysis). How have your findings been used? Please provide a brief summary. * The kinetic Monte Carlo code is under active development by the Computational Science and Engineering Group at Daresbury (DL_AKC) and a version has already been released to the simulation community under the aegis of CCP5. Further versions will be released as part of the CCP5 plans to develop general purpose codes. DLaKMC will be part of a presentation of DL_Software in Dec 2014. The methods used to investigate the self-healing properties of minerals are being used to guide the nuclear industry to a choice of better host materials in which to incorporate radioactive ions, particularly the actinides. |
| Sector | Education,Energy,Environment |
| Impact Types | Societal,Economic |
| Title | DL_AKMC |
| Description | DL_AKMC is an adaptive kinetic Monte Carlo program to study the diffusion of atoms or ions in solid state materials. |
| Type Of Technology | Software |
| Year Produced | 2013 |
| Open Source License? | Yes |
| Impact | The software is employed by approximately 30 groups including NNL and CNNC. It is also being used as part of the programme grant EP/K016288/1. |
| URL | http://goo.gl/VJKoBw |