In-situ X-ray tomographic imaging under extreme conditions: a proof of concept study

Lead Research Organisation: University of Edinburgh
Department Name: Sch of Geosciences


Performing experiments under high pressure/temperature (P/T) conditions allows us to study how materials behave in Earth's deep interior, a key step in understanding processes which formed and constantly reform the Earth. Developing new techniques for studying earth materials under these conditions provides new insight into the workings of our planet. In X-ray microtomography (CT) a sample is rotated in an X-ray beam and transmission of radiation through the sample recorded by a detector. As with medical CAT scanning, data is then used to construct 3d models of the internal structure of solid objects, although CT can also give qualitative data on the distribution of components in complex systems. Most importantly, the technique is non-destructive and samples can be studied by CT many times to observe how they evolve with time. As such, CT is ideally suited to in-situ investigations, where changes in a sample under non-ambient conditions are observed. We will test the viability of developing a novel device to study the internal structure of materials at high P/T conditions, and also whilst they are deforming. This proof-of-concept study results from 2 recent advances: (1) development of the rotational Paris-Edinburgh cell (roPEC), a device designed to allow in-situ investigations of samples held at high P/T whilst they are deforming, and (2) development of a state-of-the-art CT instrument in the School of GeoSciences, University of Edinburgh, which was specially designed to facilitate in-situ CT studies of geologically important materials. To date, only one instrument has been developed to perform detailed CT under extreme conditions. This device was developed at the APS synchrotron in the USA. Synchrotrons are intense radiation sources which produce high energy X-rays capable of penetrating much more deeply into materials than lab-based sources, and are well suited for in-situ investigations. However, obtaining beamtime at synchrotrons is very competitive; in-situ high P/T CT investigations typically take several days for one experiment which prohibits detailed investigations, and the full potential of in-situ high P/T CT has yet to be realised. We hope to develop a new device (rotating tomography Paris-Edinburgh Cell, rotoPEC) which has the key advantage that it can used for in-situ CT using both synchrotron radiation and lower intensity lab sources. This device will be based on the roPEC, in which samples are pressurised between 2 carbide anvils, heated using an internal furnace, and deformed by rotating one of the anvils, but modified to allow full rotation of the entire sample in an X-ray beam, as required in CT. The roPEC was designed for in-situ studies, and allows X-ray beams to reach the sample with minimal, unwanted absorption. It is also small enough to be transported and installed at synchrotron sources or on other lab equipment, including the CT instrument at Edinburgh. However, before constructing a rotoPEC we need to conduct a feasibility study. Specifically we will: (1) test the potential and limitations of a rotoPEC (how much detail can we observe in samples under extreme conditions...are there limitations in the types of material we can study?). As well as testing the potential of a rotoPEC this information is also required in its future design; (2) test a new type of anvil which is X-ray transparent and would increase the volume of sample which could be 'seen' during CT -the performance of transparent anvils during deformation is critical, but remains untested; (3) further develop sample assemblies used in the roPEC to minimise unwanted absorption and increase sample resolution. Whilst conducting this work we will also study the structure of melt in 2 geologically important systems: Fe-rich melt in peridotite (did deformation help Earth to form an Fe-rich core during early stages of planet formation?) and basaltic melt in olivine (how is magma transported beneath mid-oceanic ridges?).
Description The main purpose and main outcome of this project is that we have demonstrated the potential for 4-D imaging of what happens deep inside the Earth and other planets. With collaborators in Paris we have built a new device called the rotoPEC. In general terms, the rotoPEC allows us to do 3-D HDTV experiments. To start with, similar to other devices we have built, it allows us to place small samples under the extreme conditions of Earth's deep interior: the extreme pressures, temperatures and stresses. However, the novel aspect of the rotoPEC is that it then allows us to independently slowly rotate samples. By using a powerful X-ray beam, we can then collect a series of images of the sample as it is rotated, and using the same basic technique as used in hospital CAT scanning, we can construct a 3-D model of the interior of the sample. Most of the work we have conducted is based around designing components for this apparatus, and testing them using X-ray facilities in Edinburgh. However, based on the success of this "proof-of-concept" study, we successfully obtained fully-funded machine time at 2 different powerful, international X-ray research facilities: the DIAMOND synchrotron facility in Oxfordshire, and the European Synchrotron Radiation Facility in Grenoble, France. We successfully installed the rotoPEC at both these facilities and demonstrated it's potential for time-resolved studies of materials under deep Earth conditions. As such, technological development is one of the main outcomes of the project. For the first time we have shown that this type of imaging work is possible, and have significantly increased the potential for future research in Europe. We have recently obtained more time at Grenoble to do follow up studies, and have been working with the ID27 beamline scientist to develop imagining facilities which wil be freely available to everyone.
In tandem with technical development, we have also been using the rotoPEC to investigate to key areas of research. In the first major study, we performed a series of experiments to study how the Earth separated early in its history to form a dense, metallic core. For the first time we were able to show that deformation was key to this process. This has major implications for understanding the chemistry of the Earth, and of course, to understanding how planets which may host life evolve. Since the end of the project, we have continued research into this problem (funding for a PhD student, Maddy Berg). In the second study we have been studying how magma is released during melting in the deep Earth. This is a more complex study as it involves studying 2 materials which absorb X-rays in very similar ways. However, we have shown how use of small amounts of very X-ray absorbing materials can be used in a similar way to taking a barium meal during hospital imaging.
Exploitation Route We have successfully demonstrated that the Paris-Edinburgh apparatus can be adapted to allow high-resolution computed tomography (time resolved 3-D imaging) under deep Earth conditions. We are currently preparing a manuscript, with project partners, which fully describes our device. We are in discussion with beamline scientists at the DIAMOND and ESRF synchrotron sources to allow similar devices to be freely available to all scientists at the point of use.
Sectors Manufacturing, including Industrial Biotechology

Description This project has strengthened collaboration between the PI and Dr. Le Godec (Paris) and led to new collaborations with researchers in the CT group at Manchester and the i20 imaging beamline at Diamond and the ID27 extreme conditions beamline at ESRF. Based on project results, the PI successfully applied for beamtime at ESRF and Diamond to test the capabilities of the new extreme conditions tomography device. We are submitting an application to construct an optimised (smaller) CT instrument at Edinburgh based on the results of these studies. Involving beamline scientists from ESRF and Diamond in this work will ensure wide access to the broader scientific community. Work on core formation has just been accepted by Physics of the Earth and Planetary Interiors. Development work on new in-situ tomographic techniques was published at the end of 2016 in a detailed paper published by the cross-disciplinary journal High Pressure Research. I have been in contact with several groups of scientists regarding the techniques we have developed, who are interested in using our work in various different fields.
First Year Of Impact 2015
Sector Other
Impact Types Societal

Description DIAMOND beamtime for core formation, in situ tomography development study
Amount £48,000 (GBP)
Funding ID EE9185 
Organisation Diamond Light Source 
Sector Private
Country United Kingdom
Description ESRF beamtime for in situ core formation research
Amount £75,000 (GBP)
Funding ID ES-213 
Organisation European Synchrotron Radiation Facility 
Sector Charity/Non Profit
Country France
Description RSE travel award
Amount £950 (GBP)
Organisation Royal Society of Edinburgh (RSE) 
Sector Charity/Non Profit
Country United Kingdom
Start 05/2014 
End 07/2014
Title rotoPEC 
Description rotoPEC is a hydraulic press which can be used to subject samples to extreme pressures and temperatures (up to 10 GPa, 2000K) whilst simultaneously subjecting them to torsional deformation. It also then, simultaneously, allows full rotation of samples with respect to the press frame. Samples are gasketted using X-ray transparent material, and no press components surround the sample. This means that an X-ray beam can be passed through the sample as it is rotated, allowing X-ray computed tomographic imaging. 
Type Of Material Improvements to research infrastructure 
Provided To Others? No  
Impact Successful application for beamtime at ESRF (EE9185) and the ESRF (ES-92 and ES-88) to demonstrate potential for high P-T-stress tomography at both synchrotron facilities. In the future we hope that both devices will be freely available for use by other research groups 
Description Redfern 
Organisation University of Cambridge
Country United Kingdom 
Sector Academic/University 
PI Contribution Developing use of apparatus to enable imagine of geomaterials under extreme (pressure/temperature/stress) conditions
Collaborator Contribution Enabling access to deformation apparatus and preparation lab
Impact Supported successful proposal (NE/I016333/1)
Description Yann 
Organisation Pierre and Marie Curie University - Paris 6
Country France 
Sector Academic/University 
PI Contribution Leading applications for beamtime at ESRF and DIAMOND to test rotoPEC device Lead research project utilising rotoPEC device Developing facilities (roPEC) and advising/consulting over construction of rotoPEC
Collaborator Contribution provide access to rotoPEC device machine and provide at zero cost anvils and components for rotoPEC hosted and trained PhD student
Impact Development of rotoPEC apparatus Successful applications for beamtime at ESRF and DIAMOND supported application for grant NE/I016333/1
Description Doors Open Day 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? Yes
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact As curator of the Cockburn Geological Museum I organise participation of the Museum in the Doors Open day events held annually. We run tours of the museum research collection and I organise hands-on displays aimed at demonstrating the range of research collected within the School

Initiated collaboration with local artist over use of the museum collection.
Supports University Student open day and admissions.
Year(s) Of Engagement Activity 2009,2010,2011,2012,2013,2014
Description Invited talk at Scottish Planetary Science Research Network Meeting 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Other audiences
Results and Impact Invited talk for Nicci Potts, the postdoc currently employed on this grant, who spoke about work conducted to date, the purpose of the project, and the intent of the wider consortium, so an audience of scientists from across Scotland who work on all aspects of planetary sciences. The purpose of the meeting was to highlight potential for future grant applications. Dr Geoff Bromiley then spoke about work previously conducted on core formation in the Earth, and Tetsuya Komabayashi spoke about work on the voaltile element content of Earth's core.
Year(s) Of Engagement Activity 2017
Description Invited talk at joint Habitable planet China meeting, Nanjong, China 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Study participants or study members
Results and Impact Consortium meeting held in China to engage with Scientists from across China interested in the role of volatiles in planetary interiors. I gave a talk highlighting the work being conducted as part of this award, and also mentioned previous work on visualising core formation in the deep early Earth.
Year(s) Of Engagement Activity 2016
Description Invited talk, PVG joint meeting between Edinburgh and St Andrews Universities 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Other audiences
Results and Impact Invited 15 minute talk entitled "core formation in the early solar system: is everything we know about terrestrial geochemistry wrong?"
Year(s) Of Engagement Activity 2018