Atomistic Simulation Group (Posts about Rushton)

New Paper - "Thermophysical properties and oxygen transport in (Thx,Pu1−x)O2"

C.O.T. Galvin — Mon, 31 Oct 2016 12:23:49 GMT

Our latest paper exploring properties and oxygen transport in the superionic region of (Th_x,Pu_1−x)O₂ is now available:

C.O.T.Galvin, M.W.D. Cooper, M.J.D. Rushton and R.W.Grimes, “Thermophysical properties and oxygen transport in (Th_x,Pu_1−x)O₂”, Scientific Reports 6 (2016) 36024. doi:10.1038/srep36024 Open Access PDF

Using Molecular Dynamics, this paper investigates the thermophysical properties and oxygen transport in (Th_x,Pu_1−x)O₂ (0<x<1) between 300–3500K. In particular, the superionic transition is investigated and viewed via the thermal dependence of lattice parameter, linear thermal expansion coefficient, enthalpy and specific heat at constant pressure. Oxygen diffusivity and activation enthalpy are also investigated.

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New Paper and CRG Potential Update - Addition of Xe and Kr parameters for use with the actinide potential model

M.W.D. Cooper — Mon, 31 Oct 2016 11:52:29 GMT

Potential parameters have been derived for Xe and Kr in CeO₂, ThO₂, UO₂ and PuO₂.

The CRG model for actinide oxides has been effective at reproducing a wide range of properties for actinide oxides and CeO₂. Many problems relating to fuel performance revolve around the behaviour of the fission gases Xe and Kr in nuclear fuel. We have, thus, used a new approach, which combines DFT with MD at 300K, 1500K, 3000K and 5000K, to develop interactions for Xe and Kr in CeO₂, ThO₂, UO₂, PuO₂, and mixed oxides.

The fission-product model is described in our new paper:

M.W.D. Cooper, N. Kuganathan, P.A. Burr, M.J.D. Rushton, R.W. Grimes, C.R. Stanek and D.A. Andersson, “Development of Xe and Kr empirical potentials for CeO₂, ThO₂, UO₂ and PuO₂, combining DFT with high temperature MD”, Journal of Physics: Condensed Matter, 28 (2016) 405401. doi:10.1088/0953–8984/28/40/405401

The website has been updated to include the new parameter set. Additionally, the support files for LAMMPS have also been updated.

New Paper - "Effects of Gallium Doping in Garnet-Type Li₇La₃Zr₂O₁₂ Solid Electrolytes"

M.J.D. Rushton — Mon, 20 Apr 2015 14:15:39 GMT

The accepted manuscript of our new paper on gallium doping in LLZrO battery materials is now available online:

R. Jalem, M.J.D. Rushton, W. Manalastas Jr, M. Nakayama, T. Kasuga, J.A. Kilner, and Robin W. Grimes, "Effects of Gallium Doping in Garnet-Type Li₇La₃Zr2O₁₂ Solid Electrolytes ", Chemistry of Materials (2015). doi:10.1021/cm5045122

![Percolation Pathways in LLZrO][image]

The paper is the result of an ongoing collaboration between the group and Dr. Randy Jalem. Randy originally spent several months with us at Imperial whilst visiting us as a PhD student from Nagoya Institute of Technology (Japan) and we would like to thank him and the other authors for all their hard work in bringing this to completion.

Research highlights:

LLZrO is a candidate for use as solid electrolytes in battery applications.
The effects of Ga doping on the structure are considered.
Ga is found to stabilise the cubic phase.
The connectivity of Li percolation networks in LLZrO are visualised.

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New Paper - "Prediction and Characterisation of Radiation Damage in Fluorapatite"

M.J.D. Rushton — Sat, 22 Nov 2014 14:12:39 GMT

![](phosphates.png "Phosphate polyhedra weaving their way through calcium metaprisms following radiation damage in fluorapatite")

Our latest paper is now available from the Journal of Materials Chemistry A site:

E.E. Jay, P.M. Fossati, M.J.D. Rushton and R.W. Grimes, “Prediction and Characterisation of Radiation Damage in Fluorapatite”, Journal of Materials Chemistry A, (2014) doi:10.1039/C4TA01707B

In this paper we performed threshold displacement energy calculations and full damage cascades for the fluorapatite structure using molecular dynamics in conjunction with effective pair potentials. Fluorapatite is being considered as a host for the long term immobilisation of halide bearing nuclear wastes. As a result it is important to understand how the apatite structure withstands and recovers from radiation damage. Of particular interest were the structural changes noted in our damaged structures: phosphate polyhedra were found to form polymer chains, typical of phosphate glasses, that were interwoven with the calcium metaprisms forming the backbone of the apatite structure. The coincidence of these amorphous and crystalline features should help in our further understanding of the long term durability of this material.

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New Paper - "Genetics of superionic conductivity in lithium lanthanum titanates"

M.J.D. Rushton — Sat, 22 Nov 2014 11:40:34 GMT

We are pleased to announce the publication of our new paper on lithium diffusion within lithium lanthanum titanate:

E.E. Jay, M.J.D Rushton, A. Chroneos, R.W. Grimes and J.A. Kilner, “Genetics of superionic conductivity in lithium lanthanum titanates”, Physical Chemistry Chemical Physics, (2014). doi:10.1039/C4CP04834B

Lithium lanthanum titanate (LLTO) is a material that shows high lithium diffusivity even at room temperature, this makes it of considerable interest for battery applications. In the present paper we set out to try and understand how the arrangement of lanthanum atoms within this material leads to LLTO’s beneficial properties. This was achieved by using a genetic algorithm to search for configurations with particularly high diffusivities. These were then examined to see what could be gleaned from their structure in order to unlock the key to LLTO’s beneficial properties. The paper can be found here.

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New Paper - "Thermal conductivity and energetic recoils in UO₂ using a many-body potential model"

M.W.D. Cooper — Tue, 18 Nov 2014 11:22:02 GMT

We are please to announce a new publication in collaboration with ANSTO on the effect of radiation damage on the thermal conductivity of UO₂ using our recently developed many-body actinide oxide potential.

A comparison of the damage profile predicted by the many-body potential is made against previous potential models. A significant degradation in thermal conductivity is then predicted as a consequence. The conductivity of amorphous UO₂ is also calculated.

M.J. Qin, M.W.D. Cooper, E.Y. Kuo, M.J.D. Rushton, R.W. Grimes, G.R. Lumpkin and S.C. Middleburgh, “Thermal conductivity and energetic recoils in UO₂ using a many-body potential model”, Journal of Physics: Condensed Matter, 26 (2014) 495401. doi:10.1088/0953–8984/26/49/495401

New Paper - "A Concerted Mechanism for Cl Migration in Chlorapatite"

M.L. Jackson — Wed, 06 Aug 2014 14:34:22 GMT

We are pleased to announce the publication of our new paper on Cl^- diffusion in chlorapatite, a material that is being considered as a host for halide bearing nuclear waste:

M.L. Jackson, E.E. Jay, M.J.D. Rushton and R.W. Grimes, “A concerted mechanism for Cl^- in chlorapatite”, Journal of Materials Chemistry A 2 (2014) 16157. doi:10.1039/C4TA03275F

![Coupled migration sequence of two Cl− ions within a single anion channel at 1250 K over 0.64 ps viewed in (a) the [100] and (b) the [010] direction. The colour of the migrating ion denotes time such that ions of the same colour represent different ions at the same time. Cl− lattice sites are denoted by black dotted circles. ][image]

In this work the potential set previously developed for fluorapatite has been extended to include chlorine and thus chlorapatite. Previously, fluorine was observed to migrate in a quasi-1D concerted mechanism along channels in the fluorapatite [001] direction, with migration mediated by interstitial sites. Chlorine appears to migrate by a similar but distinct mechanism in chlorapatite, whereby instead of being mediated by interstitial sites migration proceeds directly along the [001] direction via a vacancy mediated mechanism, with several ions moving in concert. Vacancies are created through the formation of Frenkel pairs, with the interstitial position roughly equivalent to that of fluorine in fluorapatite.

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