A visit to the UK’s synchrotron facility | CoG3 Consortium

Researcher Dr Agnieszka Dybowska describes a recent visit to Diamond Light Source, the UK’s national synchrotron science facility, during which the CoG3 team completed their first detailed spectroscopic analysis of laterite samples.

On Thursday 28 April we headed to Diamond Light Source in Oxfordshire, hoping to carry out atomic scale analysis of a sample from the Shevchenko laterite deposit in Kazakhstan – one of the samples we’re investigating as a potential new source of cobalt.

Diamond Light Source
The synchrotron building at Diamond Light Source, Oxfordshire

For some of us this was the first visit to a synchrotron facility, and definitely a great experience!

The synchrotron at Diamond Light Source produces very intense beams of X-rays, infrared and ultraviolet light. The X-rays are 100 billion times brighter than those used in hospitals and 10 billion times brighter than the sun.

These intense beams are produced by high energy electrons travelling at almost the speed of light around the storage ring, a circular tunnel that measures half a kilometre in circumference. Observing the interaction of these beams with selected materials, such as mineral grains, allows us to study detail down to the level of molecules and atoms.

The Diamond Light Source synchrotron facility is located at the Harwell Science and Innovation Campus in Oxfordshire. It can be conveniently reached via a short train journey from London Paddington. We arrived on the evening of 27 April and prepared for our 24 hours of beam time, due to begin Thursday morning. Working together with the Diamond scientist and CoG3 partner, Prof Fred Mosselmans, we spent a long and busy day at the facility using one of the 30 unique experimental stations available there.

Experimental station at Diamond Light Source
‘Beamline I18’, our experimental station at Diamond Light Source, which allows microfocus X-ray spectroscopy, fluorescence and diffraction analysis. View of the exposed workings of the experimental hutch.

The facility seemed a bit daunting at first sight – the building housing the storage ring was enormous, with a maze of instrumentation that carries beams of synchrotron radiation to experimental end stations. By the end of the day though we could manage to navigate around the building quite well, finding our experimental station very quickly!

We completed detailed analysis of a few mineral grains that were rich in cobalt. The bright and intense synchrotron beam allowed us to map the distribution of cobalt within these grains, achieving a very good spatial resolution.

We then performed a detailed spectroscopic analysis of the cobalt. We wanted to understand how exactly cobalt atoms bond with other elements in the sample. In particular, we wanted to investigate how cobalt is incorporated in manganese oxyhydroxide mineral called asbolane, which we have identified as an important mineral host of critical metals in the Shevchenko mineral deposit.

Sample analysis
Our sample ready for analysis with high energy synchrotron X-ray beam. This image was taken just before the beam was fired onto the sample.

Using a technique called X-ray absorption spectroscopy, we collected data which will allow us to study the crystal chemistry of cobalt.  This will provide a valuable insight into how easily cobalt can be re-mobilised from the host mineral phase in the studied samples.

The X-ray beams used in this analysis are so strong that it is not safe to remain in the same room when the beam is switched on. The experimental area (hutch) has to be evacuated once the sample is secured within the beam path, and the beam and the experiment are then controlled from an adjacent room- the control cabin.

Control cabin
The control cabin, from which we can control the beam and the experiment once the experimental hutch is safely locked and the beam is on.

Having programmed an automated data collection routine, we left the synchrotron facility late at night, a bit tired but happy that we managed to collect a lot of data. The next step will be to analyse the data and prepare samples for our next visit in July 2016.

Elemental distribution map
Our first data from the synchrotron analysis: distribution of iron (green), manganese (blue) and cobalt (red) within a mineral grain of asbolane, analysed with X-ray fluorescence spectroscopy. Scale bar: 300µm.
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