It’s been 10 years since the national synchrotron science facility switched on its beams. A valuable tool for research, Diamond Light Source – an X-ray microscope, powered by electrons – allows researchers to study the molecules and atoms that make up materials.
The potential to understand materials in greater depth has attracted many researchers from academia and industry to use the synchrotron. Almost 5,000 peer-
reviewed papers have been produced from the research, and increasingly the work at Diamond is being used to develop drugs and design materials.
To boost its research capabilities, Diamond has recently launched a facility for the study of nanoscale materials, the electron Physical Sciences Imaging Centre (ePSIC). The centre contains two advanced electron microscopes designed to provide users with atomic-level images in a range of materials. The microscopes will be housed alongside Diamond’s l14 hard X-ray beamline, which uses X-rays to probe similar materials.
The ePSIC centre is a result of collaboration between chemicals company Johnson Matthey and the University of Oxford. The facility should increase the Diamond’s contribution to industrial projects, with Johnson Matthey and other big companies, such as Samsung and Rolls-Royce, set to do research there.
By combining the synchrotron’s capabilities with the two electron microscopes provided by Japanese supplier JEOL, the new facility allows users to image materials over a much greater range of length scales, says Professor Andrew Harrison, chief executive at Diamond. The microscopes can provide top-of-the line resolution down to 0.05nm.
“With X-rays, we can go up to the micrometre-length scale, and with the electron microscope it can also reveal the chemical nature of individual atoms within materials,” says Harrison. “What we hope to be doing is not producing static images but looking at transformation as processes are running.”
The ePSIC centre’s grand atomic resolution microscope has a resolution of 0.05nm – around 10,000 times smaller than the wavelength of visible light. It has fast detectors so users can “see” and analyse individual atoms in real time within the structure of the material they are testing, and gain insights on the changes it goes through when subjected to various conditions, including temperatures of up to 800°C. Angus Kirkland, scientific director of ePSIC, says: “There are only four of these instruments in the world, and it is considered to be one of the highest-resolution microscopes anywhere.”
Tapping into centre’s skills
Johnson Matthey aims to use these capabilities to research catalysts for fuel cells and better-performing battery materials. While the company could do atomic imaging at its own labs, this wouldn’t give it access to the skills in image processing or in computing and modelling that are available on the site because of its close proximity to the synchrotron, says Peter Ash, research analytical manager at Johnson Matthey.
His team will develop methodologies at Diamond, and supply that information to the company’s materials design staff, who will create intellectual property in the company’s protected environment.
In particular, the company is excited about using the electron microscopes to “see the complete picture,” right from the atomic scale up into the porous material that “operates under real gases in real life”. The research team at ePSIC can even create moving images that show chemical reactions as they happen.
“I liken where we are today to trying to watch a movie from a still image at the beginning and a still image at the end: you have to do a lot of guesswork to fill in the blanks in between,” says Ash. “With operando studies, you can take little chunks of video in the middle of your film and get some sort of narrative and story line. If you can get into the slow motion of some of those pictures, you can really start to understand what is going on and then inspire people to start developing the next generation of materials.”
The ePSIC centre will provide time for the use of the electron microscopes by a wider range of users in academia and industry for both fundamental and applied work, says Harrison. Such work will range from the construction and study of quantum electronic devices, such as a nanometre-scale bridge made of monolayer graphene suspended between two electrodes, to studying materials that could be used for reprocessing spent fuel in nuclear fission reactors.
Graphene features in work that Samsung is doing with ePSIC to develop wearable and flexible technologies based on the material. The company has already developed a prototype of a flexible mobile phone screen made from an OLED structure and a sheet of monolayer graphene backing. The material provides flexibility and also acts as a conductor. “What is critical is the presence or absence of defects in that graphene,” says Kirkland. “Too many defects and the sheet resistance is too high and these displays won’t work.”
Working with Samsung, researchers at ePSIC have developed a series of images of graphene to identify dislocation dipole structures – defects that will have an impact on the performance of the material. The team discovered that these dipoles move and migrate across the graphene lattice when being radiated in the electron microscope. “This is a big science challenge: to understand how these defects form, how we can control their formation, and how they move and migrate as a function operation of this type of device,” says Kirkland.
There is also a research programme at ePSIC looking at catalysts, in collaboration with Johnson Matthey and other companies such as South African chemical firm Sasol. The centre can image a catalyst particle at near normal operating pressures and near normal operating temperatures of around 800°C.
However, the key to the centre’s success will be the collaboration between the University of Oxford and industry, says Kirkland. “That is one great advantage of this centre – that we have industry and academics at a national facility, all working together.”
With significant players such as Rolls-Royce working with the centre to design aerospace ma-terials, and the Supergen energy storage hub planning work to explore the next phase of ener-gy-storage materials, it looks as though ePSIC could have a pivotal role in the development of solutions for some of engineering’s most pressing challenges.
DID YOU KNOW? DESIGNING FOR SENSITIVITY
The two electron microscopes housed at ePSIC are so sensitive to vibrations that they have to be protected in soundproof, anti-echo rooms built on top of cement slabs that are isolated from the rest of the building. The rooms have no air-conditioning so as not to interfere with the samples. Instead, they use cooling panels – like cold radiators – to ensure a constant temperature