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The Effect of Microstructure and Impurities on Transport in Actinide Oxide Films

微结构和杂质对锕系氧化物薄膜输运的影响

基本信息

批准号：
1789929
负责人：
金额：
--
依托单位：
University of Bath
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2016
资助国家：
英国
起止时间：
2016 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-1789929
关键词：
Effect Microstructure Impurities Transport Actinide

项目摘要

The aim of the proposed project is to develop an atom-level description of the actinide oxide films to predict the likely microstructure, the segregation of impurities and their effect on oxygen and hydrogen transport. We will use a combination of DFT and potential model techniques. Details are given in work packages (WP), which define the milestones that this project will achieve. WP1. Microstructure Generation. The current state of the art is to model surfaces or grain boundaries. The challenge for modelling the properties of the thin films is now to develop models for polycrystalline thin films, where both surfaces and grain boundaries are present. This level of complexity is necessary as these interfaces will provide the pathways for fast diffusion and they can have a profound implication for grain growth. Thus the aim of this WP is to extend the simulation tools so that we can screen through the likely structures and hence use the structures and energies to predict plausible microstructures given different possible operating conditions. These microstructures will be highly dependent on the nature of the defects present and hence we will also investigate how the interfaces and their compositions are affected by intrinsic defects.WP2. Oxygen and Hydrogen Transport. An understanding of the adsorption and transport of oxygen and hydrogen is central to understanding and ultimately controlling the kinetics of the growth and dissolution processes of the actinide oxides, which in turn will have a profound impact on the material properties. Initially, we propose to use nudged-elastic-band DFT to calculate the activation energies for migration of oxygen in the oxide layer and investigate how it changes depending on the structural features (grain boundaries and thickness of the oxide film). We will investigate the transport through the oxide film by performing constrained molecular dynamics on a range of different microstructures from which we can calculate the migration rates. Once we have evaluated the significant pathways, we will use kinetic Monte Carlo to calculate the overall rates. The latter will allow us to go beyond the nanosecond time scale of direct molecular simulations and to make direct comparison with available experimental data. The behaviour of different structural features within the UO2 matrix will be used to derive quantitative structure property relationships.WP3. Effect of impurities. All real materials are impure, and even ppm quantities of impurities are often sufficient to coat interfaces and thus the compositions of the interfaces and hence their properties may differ significantly from the bulk materials. Thus we will introduce a range of impurities to provide reliable data on their influence on the diffusion along the boundaries. The influence of doping on the transport properties in fluorite structures with representative alkaline, transition, lanthanide and actinide metals as well as p-elements will be determined. A quantitative relationship will be calculated. Furthermore, we may find that certain impurities show beneficial effects and hence we will be able to provide predictions on which dopants might be added to improve the material properties. The focus will therefore be on doping hyper-stoichiometric UO2 and use a combination of molecular dynamics and kinetic Monte Carlo.

拟议项目的目的是开发一个原子级的锕系氧化物薄膜的描述，以预测可能的微观结构，杂质的偏析及其对氧和氢传输的影响。我们将结合使用DFT和势模型技术。详细信息在工作包（WP）中给出，其中定义了该项目将实现的里程碑。WP 1.微结构生成。目前的技术状态是对表面或晶界进行建模。薄膜性质建模的挑战现在是开发多晶薄膜的模型，其中表面和晶界都存在。这种复杂程度是必要的，因为这些界面将提供快速扩散的途径，并且它们可能对晶粒生长有深远的影响。因此，本WP的目的是扩展模拟工具，以便我们可以筛选可能的结构，从而使用结构和能量来预测不同可能操作条件下的合理微观结构。这些微观结构将高度依赖于存在的缺陷的性质，因此我们还将研究界面及其成分如何受到内在缺陷的影响。氧和氢的运输。氧和氢的吸附和传输的理解是理解和最终控制的锕系元素氧化物的生长和溶解过程的动力学，这反过来又会对材料性能产生深远的影响的核心。最初，我们建议使用轻推弹性带DFT计算的活化能迁移的氧在氧化物层，并研究它如何变化取决于结构特征（晶界和氧化膜的厚度）。我们将通过对一系列不同的微观结构进行约束分子动力学研究，从而计算出迁移率。一旦我们评估了重要的途径，我们将使用动力学蒙特卡罗来计算总速率。后者将使我们能够超越纳秒级的直接分子模拟时间尺度，并与现有的实验数据进行直接比较。二氧化铀矩阵内不同结构特征的行为将用于推导定量结构属性关系。杂质的影响。所有的真实的材料都是不纯的，甚至ppm量的杂质通常足以涂覆界面，因此界面的组成及其性质可能与本体材料显著不同。因此，我们将引入一系列杂质，以提供有关它们对沿着边界扩散影响的可靠数据。将确定掺杂对具有代表性的碱金属、过渡金属、镧系金属和锕系金属以及p-元素的萤石结构中的输运性质的影响。将计算定量关系。此外，我们可能会发现某些杂质显示出有益的效果，因此我们将能够提供关于可能添加哪些掺杂剂以改善材料性能的预测。因此，重点将是掺杂超化学计量的UO 2，并结合使用分子动力学和动力学蒙特卡罗。

项目成果

期刊论文数量（8）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

surfinpy: A Surface Phase Diagram Generator

surfinpy：表面相图生成器

DOI：
10.21105/joss.01210
发表时间：
2019
期刊：
Journal of Open Source Software
影响因子：
0
作者：
Symington A
通讯作者：
Symington A

Defect segregation facilitates oxygen transport at fluorite UO2 grain boundaries.

缺陷偏析促进了萤石 UO2 晶界处的氧传输。

DOI：
10.1098/rsta.2019.0026
发表时间：
2019
期刊：
Philosophical transactions. Series A, Mathematical, physical, and engineering sciences
影响因子：
0
作者：
Symington AR
通讯作者：
Symington AR

Thermodynamic Evolution of Cerium Oxide Nanoparticle Mor-phology using Carbon Dioxide.

使用二氧化碳的氧化铈纳米颗粒形态的热力学演化。