Blog posts

PhD Spotlight: Charging ahead with battery research

Name: Connor Wright

Position: PhD Student in the Department of Materials

Research Group: Professor Mary Ryan

Research Focus: Connor is part of the newly founded InFUSE Prosperity Partnership, linking Imperial research with state-of-the-art techniques to progress the energy transition. His research focuses on the degradation of Sodium-ion batteries, widely considered the next big thing in battery energy storage.

What inspired you to study for a PhD?

Before university, I didn’t even know that ‘Materials Engineering’ was a thing. As anyone interested in the sciences at school does, I thought my options were limited to medicine, the natural sciences or the more classical engineering routes (civil, mechanical, electrical, etc.). It was only a couple of weeks before the UCAS deadline that I discovered – thanks to my sixth form tutor (thanks again, Mr Hunt!) – the wonders of Materials Engineering.

I applied for and got accepted onto the course at the University of Birmingham and have never looked back. The top-down approach, where you start with an application, assess the materials requirements, and then go to work on manipulating materials at the most fundamental level to achieve these, was something that really resonated with me. In my third year I chose a battery-related group project, thinking they were a worthy application to focus on with this top-down approach. In my Masters’ year, I again chose batteries for my individual project, focusing more on recycling. Continuing onto a PhD was the logical next step. I love the research culture, and where better to go than Imperial!

Sodium-ion Batteries that Connor created and tested.

Can you tell us more about your research?

I focus on cathode materials for sodium-ion batteries (NIBs). Like lithium-ion batteries (LIBs) that we all have in our mobile phones, NIBs work by shuttling and storing positively charged ions and atoms, respectively, between two electrodes. The key difference is that NIBs use sodium, which is cheaper and more sustainable than lithium but heavier and less energy-dense. These properties make NIBs suitable for large-scale energy storage solutions and very suitable for renewable energy conversion like wind and solar. While current grid-scale storage relies heavily on pumped hydro, its cost and geographical constraints limit its global application. NIBs could be the bridge to a fully decarbonised society.

The InFUSE group.

My work aims to understand why some promising NIB materials degrade as fast as they do. I engineer methods to study these materials at the smallest scale and in real-time, as they charge and discharge. These specific techniques are labelled ‘operando’.

At the UK’s national synchrotron facility, I conduct experiments that involve firing high-energy X-rays into my batteries to gather all sorts of useful (and awesome) information. One key technique, X-ray Absorption Spectroscopy (XAS), provides insights into the chemical and electronic structure of the host electrode material. Looking for unusual changes in the XAS signal as my target electrode charges/discharges is a large part of what I do as a researcher.

What does a typical day involve?

A typical day would see me in the lab making and testing batteries. Production is a complicated and multi-step process, so depending on which stage I’m at, this could mean using furnaces, slurry mixers, coating machines, or the testing/cycling rig. Most days will also involve some sort of data analysis, either cycling data from the lab or some more hardcore stuff from a recent synchrotron experiment. However, as with all research, no day is ever the same, and things are always changing!

Can you tell us more about your research group?

I work in two different groups, which is not uncommon here at Imperial. My primary supervisor is Prof. Mary Ryan in Materials, but most of my lab work is with Prof. Magda Titirici’s Battery team in Chemical Engineering. In my second year, I organised Mary’s biweekly group meetings and also went to both France and China with Magda’s group for conferences.

What do you enjoy outside of your PhD?

I wouldn’t be where I am today if it weren’t for sport. I’ve played field hockey my whole life, and throughout the PhD is no exception. I also love music and regularly attend a ‘pub choir’ in south London with many friends. Coming from a farm in rural Leicestershire, I also need my regular dose of fresh air and greenery, so I often take hikes out of London with my girlfriend.

Slightly closer to home, I enjoy my work as an Outreach Ambassador for the Department of Materials. As I said at the start, not many people know about Materials as a field, let alone a degree or career option, and that’s a real shame! I’ve done lab demos at Imperial’s Open Days, helped run stands at public events such as The Great Exhibition Road Festival and even organised my own event for 2023’s Pint of Science Festival.

The group of Professor Mary Ryan on an outing to Dishoom.

Alumni spotlight: Dewen Sun on co-founding DeSolve Technology

Name: Dewen Sun

Degree: MEng Materials Science and Engineering in the Department of Materials

Graduation Year: 2023

Current role: Head of R&D and Co-founder of DeSolve Technology (LinkedIn) and PhD Student at Ruhr University Bochum

  • Can you tell us about your current occupation and company? 

I am continuing my studies in Germany, pursuing a PhD in solid-state physics. My specialisation is quantum mechanical modelling and machine learning, which is also the focus of our start-up. This position not only allows me to enhance my knowledge in a structured and systematic manner, but it also provides a connection to the academic world, which is invaluable for an early-stage startup like us.

  • What inspired you to start this company?

A casual dinner conversation. My friend from Biochemistry mentioned the issue of insolubility when developing drugs. Many promising new compounds fail due to their lack of solubility in water, preventing them to be absorbed by our body. This forces researchers to develop complex carriers, which is still done largely through trial and error. This struck a chord with me. Having spent three summers working on solvent development within our department, I realised that the techniques that we have been using could also be applied here.

Putting our ideas to work, we decided to start a company developing drug carriers. We are working to provide a software solution that designs tailored carriers for individual drugs. Since then, we have been constantly energised by the prospect of contributing to the vital field of drug delivery and excited by the huge challenge ahead.

  • What are your ambitions for the future? 

Within our first year, we established many partnerships with commercial and academic experts in the field and are on track to develop a fully functional demonstrator by 2024. We are now working towards two aims in the coming years:

First, we will begin full collaboration with our laboratory partner to validate the scientific functions of our software and gain credibility for our product. We are also looking at beginning early-stage commercial rollout of our product and concept.

This will set us on track to becoming an established company for carrier development, providing a trusted and well-recognised product in the field. It will also allow us to maintain invaluable relationships with all players in the pharmaceutical field.

  • What piece of wisdom can you share with students?

The best advice I have is to make use of every available resource at Imperial.

From our colleagues and lecturers to the entrepreneurship programs, I would not have dared to do any of this without them. It was the incredible knowledge and insights of my colleagues that gave me the inspiration and the confidence to start this business. I would not have the capability to lead the research and development of such a complex product without building experiences through the Undergraduate Research Opportunity Programme.

The business, marketing, and IP training from the Imperial Enterprise Lab was also absolutely invaluable. It helped us evaluate and reevaluate our business and refine our strategy, setting us on the right path.

Meet our postdocs: Celebrating National Postdoc Appreciation Week

National Postdoc Appreciation Week (PAW) is a celebration of the fantastic contribution postdocs and researchers make towards research and academic life. Held every year from 18 – 22 September, the week is a chance to thank our postdoctoral researchers and everything that they do!

To celebrate this week, we hear from five postdocs from the Department of Materials.

Dr Jerry Sha – ‘Our community enables me to address challenges in my research and career development every day’

Dr Jerry Sha is a Research Associate in the group of Professor Stephen Skinner. He joined the Department as an undergraduate student in September 2013.

Jerry is part of a project called Epistore, funded by Horizon 2020. The group are aiming to revolutionize the energy storage sector by developing new innovative cells that could efficiently store renewable electricity and cater to applications where the use of conventional batteries is impractical. This includes overcoming size limitations or long-term storage needs. Applications for this research could include off-shore power generation and transportation.

Outside of research, Jerry enjoys playing piano, photography, reading, and karting.

He comments: “I greatly appreciate the inclusivity and support within the postdoc community, which has enabled me to address various challenges in both my research and career development every day. I am also grateful for the opportunity to develop friendships with people from diverse backgrounds.’

Dr Anna Winiwarter – ‘ I enjoy the events organised by my peers’

Dr Anna Winiwater is a Research Associate in the group of Professor Ifan Stephens. She joined the Department of Materials this year.

She is involved in creating an eco-friendly method to produce ammonia, a vital ingredient for fertilizer that feeds half the world’s population. The traditional method, known as the Haber-Bosch process, emits a lot of CO2, contributing to global emissions. Using air’s nitrogen and renewable electricity, the group are working on an electrochemical approach that offers a cleaner alternative. Her research focuses on detecting ammonia and unwanted side products using online mass spectrometry.

Outside of research, Anna enjoys like dancing (in particular Argentine tango), baking sourdough bread, hiking and generally being in nature as a balance to the busy life as a postdoc.

She comments: “I feel very welcome and supported by the postdoc community, both through events organised by peers (like the monthly breakfast for Materials postdocs) and the wide range of services provided by the PFDC.”

Dr Pankaj Sharma – ‘Becoming a member of the postdoc community has been a wonderful experience’

Dr Pankaj Sharma is a Research Associate in the group of Professor Fang Xie. He joined the Department of Materials this year.

Pankaj’s research involves the synthesis of plasmonic photocatalysts for green energy production and environmental applications. He engages in activities related to photoreduction and electrochemical conversion of CO2, the valorization of biowaste, the intergration of catalytic processes for valuable chemicals, and the exploration of photocatalysts for medical and cosmetic applications.

Pankaj is also involved in exploring seawater batteries for hydrogen storage and production, nanomaterial development, synthsising multifunctional porous/hybrid materials, investigations into gas separation, and membrane fabrication.

Outside of research, he enjoys watching regional cinema, occasionally cooking, and savouring delicious food.

He comments: “Becoming a member of the postdoctoral community at Imperial has been a wonderful and novel experience.”

Dr Megan Owen – ‘Our research could impact clean energy generation’

Dr Megan Owen is a Research Associate in the group of Professor Sir Robin Grimes. She joined the Department of Materials in 2022.

Megan’s research uses simulations to model nuclear materials like fuel and cladding. She works to analyse materials during operational temperatures and beyond operational temperatures to better our understanding of materials’ properties.

The group are aiming to develop an understanding of future nuclear materials for new reactors, which will be beneficial for clean energy generation to meet net-zero targets.

Outside of research, Megan enjoys Côr Llundain (London Welsh Choir), attending the gym, and baking.

She comments: “I’m happy to be a part of the postdoc community at Imperial. The PDFC provide excellent support for progression, and monthly coffee mornings and social events within Materials allows me to meet and collaborate with other postdocs.”

Dr Apostolos Panagiotopoulos – ‘I feel constantly inspired to excel and innovate’

Dr Apostolos Panagiotopoulos is a Research Assistant in the group of Professor John Kilner. He joined the Department of Materials in 2018 as a Research Postgraduate.

The group’s research aims to pioneer upscalable and sustainable routes for the processing and manufacturing of electrochemical energy storage components towards high performance devices. His research focuses on exploring their operating intricacies, benchmarking and unveiling charge storage mechanisms. This allows him to re-envision components with superior design, streamlined supply chains and safer function. Apostolos hopes to integrate these innovations in trusted and bold new industrial landscapes, pushing us a step closer towards net zero.

Outside of research, he enjoys competitive fencing and sailing. Apostolos also enjoys cycling, weight-lifting, dancing and has recently started badminton at college.

He comments: “I feel constantly inspired to excel and innovate by the Imperial community. Every day, presents an opportunity to learn and enhance a variety of skills.”

PhD Spotlight: Titanium Alloys for Tomorrow’s Orthopaedic Implants


Name: Jessica Tjandra

Position: PhD Student in the Department of Materials and Centre for Doctoral Training in Advanced Characterisation of Materials (CDT-ACM).

Research Group: Dr Stella Pedrazzini

Research Focus: The corrosion of additively manufactured titanium alloys for custom orthopaedic implants.

What inspired you to study for a PhD?

In the penultimate year of my undergraduate course (also in the Department of Materials at Imperial), I spent the summer as a UROP student working with Dr Stella Pedrazzini.

I was working on a Rolls-Royce project replicating salt corrosion in single-crystal nickel superalloys used in turbine blades in jet engines. On the first day of my UROP, Stella and I attended a Rolls-Royce meeting in Derby, allowing me to meet my industrial supervisors. What fascinated me the most was when Stella introduced me as her student who would be conducting the project – it was mind-blowing that in a room full of materials science experts, I could try to solve a problem that would affect all future Rolls-Royce engines! At the end of my UROP, we returned to Derby to report my findings, which was very fulfilling. There was a lot of scope for future research in the area, allowing me to continue my experiments as my final year project.

It excites me that I am trying to solve a problem that will benefit industry and society directly and see the concrete impact of my research in the future.

Can you tell us more about your research?

My current research focuses on the corrosion mechanisms of additively manufactured titanium alloys for custom orthopaedic implants. Implants such as knee and hip replacements tend to be made from titanium alloys that are forged (shaped into their final shape using applied forces, such as with a hammer or a die). Additive manufacturing (AM), or 3D printing, allows us to produce complex-shaped implants for patients requiring bespoke devices. This will hugely benefit patients who cannot utilise mass-produced implants, such as bone cancer patients, young children, and patients requiring revision surgeries from previously failed implants.

Figure 1 One of the AM lattices studied using a scanning electron microscope showing unmelted powder on the lattice surface.

The issue with additive manufacturing is that the components produced tend to have defects from the manufacturing process. They also contain more oxygen which causes the component to be more brittle. The porous structure of the implants, called lattices, also means that they are more susceptible to corrosion damage. Once placed in the body, these implants will be exposed to blood plasma, body temperature, and forces from body movement.

My work replicates these environmental factors to AM titanium lattices to interpret the corrosion mechanisms of the implants, especially with applied mechanical loading. Knowing the durability and safety of AM implants is important as they will reduce the need for revision surgeries in the future, benefiting patients and the NHS.

I use materials characterisation techniques such as atom probe tomography (APT) and energy dispersive spectroscopy (scanning tunnelling electron microscope – STEM-EDS) to determine oxygen concentration around crack tips from fatigue loading and across grain boundaries with different crystal orientations. Furthermore, I work with colleagues from my industrial collaborator, Alloyed Ltd, to determine the best way to manufacture these lattices, with complex shapes and overhangs, accommodating components such as nails to attach them to neighbouring bone.

What does a typical day involve?

My day varies a lot depending on the stage of my PhD. Last year, I spent most days conducting many compression fatigue tests of my lattices, some of which lasted a month per test! Currently, I am mostly preparing APT samples using the focussed ion beam (FIB) facility. I usually spend a bit of my day reviewing new literature on similar topics, writing papers for publication, and making pretty figures that I can later use in conference presentations and my PhD thesis. The rest of my day usually involves meetings with my supervisor or undergraduate/master’s students.

Can you tell us more about your research group?

My research group (the metals electrochemistry group, led by Dr Stella Pedrazzini) is undoubtedly one of the reasons I enjoy doing my PhD so much. We meet once a week to update each other on what we have been up to, whether it is a failed experiment, writing research proposals, or going on holiday!

What do you enjoy outside of your PhD?

I enjoy doing STEM outreach and am an active Discover Materials Student Ambassador and Departmental Student Ambassador. Materials is such a great field to be in, and many people are unaware of its existence! I have delivered many workshops, lab demos and presentations to young people about my research and materials science at events like The Great Exhibition Road Festival, Big Bang Science Festival, Cheltenham Science Festival, College Open Days and more!

Outside of work, I enjoy cooking and baking. Coming from Indonesia, I also play the Javanese gamelan, a traditional ensemble music made up of metallophones, gongs and drums. We play at various gigs and practice every week.

Inside the workshop: With Russell Stracey and Mike Lennon

The RSM workshop, located on the lower ground floor of the Royal School of Mines, serves as a central machining facility providing design and manufacturing support for all three Departments within RSM: Materials, Bioengineering and ESE. It has a comprehensive range of both manual and CNC machines; some of the manual machines date back to the old Metallurgy workshop and have been in operation since the 1960s.

Russell Stracey, RSM Workshop Manager, became a part of the workshop team in 2008, while Mike Lennon, Mechanical Workshop Technician, joined in 2013. We had the opportunity to speak with Russell and Mike to learn more about the workshop’s evolution over time, exciting projects, and their personal highlights.

Can you tell us more about the workshop?

Mike: Workshops are important to produce of a wide range of goods. When you think about it, everything around you is likely created in a type of workshop, from transport to household items and clothing – it just depends on the size, scale, and capability of the facility. In the Department of Materials, we focus on making components that can support research or teaching – and we are always up for a new challenge!

Russell: When you look around our workshop, there are a range of drilling, cutting and creating machines – both old and new. The workshop’s physical layout has undergone significant transformations throughout the years. When I arrived in 2008, it was three times its current size and occupied multiple floors! Furthermore, our team has expanded, welcoming additional staff members. Over time we have introduced CNC machines alongside traditional manual machines, enhancing our operational efficiency. Some of the old machinery still has a valuable purpose in supporting our work – the oldest facility here dates to the 1960s!

What’s a typical day like?

Russell: A typical day for us can be quite varied! We usually focus on machining experimental components for our PhD students and researchers to support their projects across a wide range of disciplines, from engineering alloys to medical and energy applications. We also manufacture samples for tensile testing that our UG students use during their labs

Most parts machined in the workshop are made from metal or plastic. In recent years, we have witnessed a growing demand for the use of new materials such as Peek. Peek is a fairly new material. It has become an increasingly popular material, replacing PTFE for sample holders, as it doesn’t contaminate the material which is being tested, is a more stable material from a machining perspective and is able to operate at higher temperatures.

Can you tell us more about collaborations and projects that you have been involved with?

Mike: We have opportunities to be involved with unique research projects. For example, I enjoyed machining parts to support Professor Neil Alford with his research into diamond masers (a microwave laser) which work at room temperature.  This idea was suggested in the 1970’s but no one had managed to create a diamond maser because they all used microwave cavities – a metallic cylinder with connectors –  made by the manufacturer of the big magnets used in the experiment. Professor Alford asked if I could create a cavity in oxygen free copper to support the world’s first diamond maser. The group are now trying to miniaturise the device, so I’m helping to build microwave cavities for this research.

Russell: We’ve also machined parts to support the ‘design study’ projects created by our undergraduate students. Sometimes, they just needs a small part or tweak to get it working properly! Recently we have created hundreds of custom ‘materials bucky ball’ key rings for the Great Exhibition Road Festivals and Open Days too, which was a new challenge!

What do the team most enjoy about their roles in the workshop?

Russell: What I enjoy most about the role is meeting people and working with the team. In the workshop, you get to work with many people with great ideas for making the world a better place. If we can be just a small part of that stepping stone to support their research, it can feel very rewarding.

Mike: I’ve really enjoyed the opportunity to train our apprentices. I first started training apprentices 11 years ago, and I’m currently training my last! It’s been fantastic to see younger technicians learn new skills over the years and take these forward in their new roles.

Materials Science in the real-world: Insights from our student placement

Divija Sachdeva and Roman Ogorodnov, two undergraduate students from the Department of Materials, have recently finished their learning placement at AlixLabs in Sweden. Throughout their placement, they conducted an investigation into semiconductors fabrication.

Divija and Roman sought out their placements through networking and direct applications on LinkedIn. Their placements were independently funded and conducted during the Easter break.

In this blog post, they share more about their placement, what they learned and how this will positively impact their future studies.

Being Materials Science students, every day, we learn more about the pillars of its foundation and the technologies in the current modern world that are still in the developing phase. We start this degree with a rough (engineering) drawing of what our future aspirations are, which soon become the drive to be a part of the revolution for new sustainable and revolutionary materials. Roman and I wanted to learn more about the fabrication of semiconductors and advanced transistors because of our heavy interest in exploring how the new techniques for etching are being developed and being a part of it. 

Our placement with AlixLabs

In April 2023, we had the opportunity to interact with the Researchers at AlixLabs in Lund, Sweden, during a three-week learning placement under their supervision. On our first day, we sat down with Dr Dmitry Suyatin, the Co-founder of AlixLabs, who explained to us their vision, which was to develop a specific Atomic Layer Etching (ALE) method to manufacture nanostructures with a characteristic size below 20 nm. For context, ALE is a technique used in semiconductor fabrication which removes one atomic layer at a time from the material surface (in this case, a Silicon wafer) by exposing it to a reactive gas/plasma. 

The newly discovered method at AlixLabs allows ALE to be selectively performed on inclined surfaces – which in turn can be fabricated by epitaxial growth and dry etching. Our task was to get an approximate of how GaP (Gallium Phosphide) will be etched if chlorine (Cl) was used as the plasma and obtain the values of surface energy required for it. To achieve this, we used the Espresso and Jaguar software provided through Schrödinger, which allowed us to build a GaP crystal and turn it into a slab having some amount of vacuum space. Upon adding a Cl2 molecule into this vacuum and by importing pseudopotentials of Gallium, Phosphorus and Chlorine, we ran the chlorination simulation on the software.  

The goal at AlixLabs is to research more about the etching process on inclined surfaces of GaP wafer to make it more widely used and cost-efficient. By running simulations of its etching using different variations of plasma, including Chlorine, we were able to have approximate values of how much energy consumption is needed. Furthermore, by doing SEM analysis and Ellipsometry, we were also able to study the width of the wafers after each round of etching. The ALE process, devised by AlixLabs, has the potential to make nanostructures smaller than 20 nm – which will enable the placement of more transistors on one chip, allowing for an even faster response time for devices. 

If successful in enabling this new method of ALE for large-scale use, this would be an economically affordable method and will also produce fewer by-products which are not sustainable. The faster response time and increased longevity of all the devices which use semiconductors, such as mobile phones and medical devices, will also contribute to reducing e-waste. The key challenge is increasing the consistency of the etch rate and improving the implementation of the Schrödinger software for our desired goal, and increasing the speed of the process.  

Reflecting on our placement 

All in all, we really enjoyed the experience of being able to contribute our part and have this opportunity to travel to Sweden and learn more about AlixLabs and semiconductors. This has certainly deepened our knowledge in this research area, and we are very grateful to continue our alliance with them.

We plan on pursuing the modules of Optoelectronics and Nanomaterials in our years 3 and 4, which have semiconductors at the heart of their foundation. This placement has been a strong starting ground for us to apply the knowledge we have and will gain regarding fabrication and quantum mechanical effects of semiconductors directly into research.   

Leading a sustainable initiative: Marta Chiapasco on reducing waste in the lab

Name: Marta Chiapasco

Position: Research Postgraduate in the Department of Materials.

Research Group: Professor Alex Porter

Research Focus: Plastic degradation and whether we can make more environmentally friendly plastics. 

In this blog post, Marta talks about starting a new initiative to recycle plastic gloves. By implementing this new scheme, it is estimated that the Departments of Materials and Bioengineering will save approximately 2 tonnes of single-use waste a year.

Hi, I’m Marta! I am a PhD student, and my research is about understanding how degradation progress in plastic packaging with different microstructures. I work with the startup Polymateria, accelerating the degradation of plastic once released into the environment. Plastic degradation and pollution have been my primary academic interests since the early stages of my education. Plastic pollution is a manufactured problem; therefore, it should be easier to solve in theory!

Recently I thought about introducing the scheme of single-use glove recycling at the Royal School of Mines because I always wanted to do something about the vast amount of waste generated in scientific labs – through plastic, energy and water overuse. I’d heard about glove recycling schemes at other universities and thought if they could do it, we could too!

Now making a positive change can take time, so for the first step, I convinced my lab to try to reduce our environmental footprint by getting certified by the LEAF program. The LEAF program helps research groups take small actions and change behaviours to reduce research’s environmental impact and save materials, energy, and money. By starting this initiative, we learned so much about energy usage and waste – for example, one fume hood consumes the same amount of energy annually as an apartment! In addition, our research group found impressive savings by lowering the hush and decreasing the airflow when not in use. I recommend anyone to join this programme!

After completing the LEAF program, I wanted to involve more people. I stumbled upon the Right Cycle scheme through the website of Terracycle, and I thought, ‘this is exactly what’s missing!’ in our facilities. Terracycle is one of my favourite companies: they recycle materials that municipalities usually do not recycle because they are too complex or expensive. Recently they collaborated with Kimberly and Clark, launching a program to mechanically recycle single-use gloves to reuse the materials to make toys, vases, benches and more. So, with the valuable help of staff members around the college, Cora O’Reilly, Nana Asamoah-Danso, Kenneth Keating, Paul Kirton from the SK stores, the sales team of Avantor, we managed to put the scheme in place within six months. This was an incredible feat, and I’m so grateful for everyone’s help in making this important initiative a reality in the Departments of Materials and Bioengineering.

Together we are stronger and can make a difference – we cannot keep pretending that someone above us will solve the problem. So I encourage everyone to get involved and support the Terracycle initiative – they also support recycling centrifuge tubes and rigid plastics if you’re interested in recycling these too!

I am so proud of what we have achieved and look forward to seeing what we can achieve as an institution when more people take a stand against plastic. Every choice matters. Reduce, Reuse, Recycle!

Find out more about the Rightcycle scheme and learn more about Marta’s research.

Quantum Potential: Dr Max Attwood on developing organic materials for quantum technologies

Name: Dr Max Attwood

Position: UKRI Quantum Technology Career Development Fellow in the Department of Materials.

Research Focus: Developing organic materials for quantum technologies and a type of quantum sensor called the “maser”.

Can you tell us more about your research area?

My research fellowship centres around developing organic materials for quantum technologies, most pressingly, a type of quantum sensor called the “maser”. These masers are the microwave equivalent of a laser, and the word itself is an acronym for “microwave amplification by stimulated emission of radiation”. Such devices have the potential to amplify extremely weak radio/microwave signals within a narrow bandwidth with extremely high signal-to-noise ratios (SNR).

Masers, originally conceived in the 1950s, have historically been used as sensor components inside space-facing radio telescopes. However, due to their thirsty consumption of liquid helium, which was required to sustain their low-noise characteristics, these classical masers fell from favour after the 1970s, mainly being replaced by cheaper field-effect transistor devices.

Interest in these devices was reinvigorated in 2012 when a team of researchers led by Professor Mark Oxborrow and Professor Neil Alford of Imperial College London demonstrated the world’s first room-temperature solid-state maser.[1,2] Built using an organic crystal of para-terphenyl doped with the “workhorse” molecule known as pentacene, this work represented a significant shift in terms of the maser gain medium and underlying mechanism governing its operation.

When irradiated with yellow light, one electron in the outermost orbital of pentacene becomes spin-inverted, switching the “state” of the molecule from singlet to triplet. In this triplet state, electrons can exist in one of three distinct energy levels that emerge due to interactions between electrons of the same spin. For some molecules such as pentacene, electrons preferentially occupy the uppermost state due to a process of spin-inversion known as “spin-selective intersystem crossing”, thereby generating a strong population inversion. The difference in energy between the uppermost and lowest energy levels corresponds to a microwave frequency of 1.45 GHz. When a microwave photon of 1.45 GHz interacts with a crystal containing lots of triplet-state pentacene molecules, it “stimulates” an avalanche of electrons from the uppermost energy level to the lowest. This simultaneously produces an emission of photons at 1.45 GHz, effectively amplifying the stimulating photon by several orders of magnitude – enough to produce an electrical impulse in a coupled detector.

Figure caption. An “invasively” pumped pentacene-doped para-terphenyl (Pc:PTP) maser device. Here, a crystal of Pc:PTP can be seen to fluorescence red whilst being pumped by yellow light guided through an optical waveguide. The transparent puck of strontium titanate acts as a resonator. Image credit: Michael Newns, PhD student in the Oxborrow group.

Thanks to these findings, masers can be used to help detect any phenomenon that might operate or occur at a resonant microwave frequency. This includes sensing extremely small deviations in magnetic field strength or perhaps a single electron spin-flip. I’m interested in the latter example because of its potential to work in tandem with quantum spin-based technologies, including memory devices and communication networks. Before masers can become competitive with contemporary devices, we must find materials that improve their energy efficiency and reduce the impact of non-signal (i.e., noise) photons naturally emitted by ambient objects. This means testing new workhorse molecules instead of pentacene and new host molecules instead of para-terphenyl.

What are the main aims of your current research?

My research aims to build a library of efficient organic maser systems capable of sensing at various frequencies and under significantly dulcified operating conditions compared to the current pentacene-based maser.

As a chemist, my job involves synthesising and analysing new materials with properties that are open and responsive to maser applications. For new host molecules, we look for systems that are chemically inert while also being able to encapsulate a wider range of “workhorse” molecules at a high concentration. In all cases, the more molecules, the better!

We manipulate these properties by changing the chemical structure of guest and host components and determining maser devices’ operating conditions, sensitivity, and output power. In a perfect world, every photon of absorbed light would produce a triplet state with a population inversion!

How could this research potentially benefit society?

A significant advantage of masers over contemporary high electron mobility transistor (HEMT) or superconducting interference device (SQUID) based microwave sensors is their remarkable signal-to-noise. To achieve low-noise figures, these devices require cryogenic refrigeration however, masers operate at room temperature.

High signal-to-noise means that we require fewer repeat measurements of signals to average out background signals. For example, in electron paramagnetic resonance (EPR) spectroscopy, a technique that uses microwaves to detect electron spins, the signal-to-noise ratios are proportional to where is the number of measurements. If we doubled the signal-to-noise ratios, this would result in 4x fewer scans.

This advantage could be used for equipment like nuclear magnetic resonance (NMR) spectroscopy or magnetic resonance imaging (MRI) scanners in hospitals. Currently, NHS patients can expect to wait for more than three months for an MRI scan, so enabling faster scan times could significantly enhance their availability.

What are the next steps in your research? 

Finding materials that exhibit all the qualities required to build a compelling maser device is complex, and we usually must settle for a compromise.

Often, molecules that exhibit a high triplet yield following irradiation with light have short spin relaxation times. This is because the mechanism that enables the formation of triplets, known as “spin-orbit coupling”, also makes it easier for the spin of an electron to flip. Furthermore, we often find that our workhorse molecules are chemically incompatible with known host molecules. Such issues stem from the fact that polar molecules prefer to interact with other polar molecules (like each other).

Therefore, we often rely on glass-forming materials that provide excellent optically clear media form, but light excitation can cause triplet-state molecules to occupy a disordered and inhomogeneous molecular environment. The consequence is that the spin-spin relaxation time diminishes significantly, causing the spread of emission frequencies to expand, which reduces the output power for any frequency we might like to study. Known as “inhomogeneous broadening”, this effect is minimised in crystals which form highly ordered 3D structures at the molecular level.

One of my primary research goals is to synthesise a universal host that can encapsulate a wide range of candidate maser molecules and significantly expedite the discovery and screening process while also ensuring an ordered crystalline environment. I would also like to build on the available computational tools that can calculate and predict the properties of future maser candidates.

References:

[1]      M. Oxborrow, J. D. Breeze, N. M. Alford, Nature 2012, 488, 353–356.

[2]      J. Breeze, K.-J. Tan, B. Richards, J. Sathian, M. Oxborrow, N. M. Alford, Nat. Commun. 2015, 6, 6215.

PRIDE Spotlight: Sophie Kay on supporting LGBTQ+ students and her new radio show

Materials Undergraduate student, Sophie Kay, shares more about the importance of a supportive community, finding her place at Imperial and her new role leading a LGBTQ+ radio station for Radio Society.

Thinking back to when I was applying to university, what I was most excited about was societies. Having heard the rumours that STEM degrees are hard work, I was determined to find my people and have a good time.

I first visited Imperial back in 2017, having travelled down to London with my family. It was my first taste of a possible life at university and to say I was excited was likely an understatement. I spent the 200 mile train journey back home scrupulously scanning the Imperial College Union website for the most interesting societies – Cheese Society (now sadly defunct, RIP Big Cheese), KnitSock, Film Society, then I came across IQ. At this point in my life I was just beginning to accept my sexuality and clung on to any morsel of LGBTQ+ representation I could find. I was a pleasantly surprised at how strong its membership was – and even more pleasantly surprised at how gender-balanced the committee seemed to be.

As I grew to accept myself more, I found myself becoming frustrated with the world around me. The joy brought by a strong community of both LGBTQ+ individuals and allies, such as those found in IQ, Imperial 600 and organisations such as QPOCPROJECT should never be underestimated, both in impact and importance. There is surely no shortage of struggles to be had however, the beauty of being in community with others is to help lighten the load of the bad times and make the good times shine brighter.

Earlier this year, Radio Society advertised an opportunity to have a radio show so I just jumped on it! I’ve been making themed playlists just as a hobby for years now and always wanted to share them beyond Spotify without being too awkward about it so it seemed right up my street. I’ve found LGBTQ+ artists, especially female, transgender and non-binary artists, to be severely underrated so I just wanted to spread the word about my favourites so more people could enjoy their music, every Sunday from 9-10pm on icradio.com.

STEM can feel very homogenous at times, and it’s very easy to let imposter syndrome seep in and make you think that because you don’t see people like you often, that STEM is not for people like you. It can also make you feel pretty uncomfortable to be openly yourself, however, if you know that there are people around who are proud of their identity and supportive of building a more accepting environment, that can have a domino effect.

Celebrating International Women In Engineering Day

Did you know that just 16.5% of the engineering sector are women? 23 June is International Women In Engineering Day, an international celebration to raise the profile of women in engineering and focus attention on the amazing career opportunities available to girls in this exciting industry. 

In the post below, four women in our fantastic community share more about their careers and how they are helping work towards a better future.

Dr Stella Pedrazzini, Lecturer in Engineering Alloys and Metallurgy

I work on the environmental degradation of engineering alloys. I look into the oxidation and hot corrosion of nickel and cobalt based superalloys and aqueous corrosion of steel. To this day, very few research groups around the world work on corrosion due to the challenges involved in this type of investigation. My research group also consists of mostly women – which is very unique in STEM. I also teach the 1st year undergraduate module in Materials Electrochemistry.

My research group is divided by material: we have people working on steels, on nickel-based superalloys, on titanium alloys and more recently on zirconium too. The noble metals are the only ones that don’t corrode (…easily!), everything else is worthy of investigation. Some of the work from my own research group has helped inform the corrosion rates of aero-engines, industrial gas turbines, nuclear reactors and medical implants exposed to body fluids.

I’ve been doing Outreach for ten years, including workshops, talks, and experiments. For me, the motivation for Outreach was primarily the lack of women in Science. My aim is to put the word out there that women can do science and engineering too and it’s important to change perspectives from a young age. For example, when asked to draw a scientist, many primary schoolchildren picture Albert Einstein. However, when asked to draw a scientist after I had presented a talk, schoolchildren were more likely to draw female scientists too!

Dr Jang Ah Kim, Research Associate 

Light contains so much information about all the materials in nature. The more in-depth we analyse all the shades of light interacting with matter, the richer details are revealed and nanotechnology helps boost light-matter interactions. I utilise nanotechnology to develop smart sensing platforms boosting these light-matter interactions to detect disease biomarkers. We expect that the sensing platform would allow for fast screening of diseases, and therefore the early detection and treatment of diseases in the future.

My peer researchers around me are the greatest inspiration. I am in a highly multidisciplinary, international and gender-balanced group, which is very special in academia. In this unique environment, there is always something to learn from the peers – not only about their research topics but also about different viewpoints, problem-solving skills, aspirations and attitudes towards life and career. This is why I have never gotten bored of working in academia, and what inspires me to grow every single day to be a better researcher.

 

Dr Irena Nevjestic, Research Facility Manager

I am the facility manager for the SPIN-Lab research facility in the Department of Materials. SPIN-Lab straddles three faculties at Imperial and the London Centre for Nanotechnology. It is a state-of-the-art hub of magnetic characterisation to study spin-related phenomena which includes equipment for the study of strongly coupled and isolated spins. This combination of techniques is unique and it offers an insight into the fundamental properties of materials but also prospective applications of how these can be utilised.

I meet a lot of different researchers in my role, which I find the most exciting part of running the lab. Since the SPIN-Lab is an open-access facility, I also have the opportunity to work with lots of users on different projects, which I really enjoy. This week, I had the chance to work on something that was completely new to me, which was a great new learning curve!

Dr Reshma Rao, Research Associate

I work on discovering active, stable and low-cost materials that can catalyse green hydrogen production from water using renewable electricity.

I use a range of operando techniques to understand how such materials function and degrade under the harsh operating conditions they experience in water electrolysers. The term operando (Latin word for working) refers to a class of analytical techniques where a catalyst under operating conditions is monitored in real-time and simultaneously characterizes its activity as well as selectivity. Using this atomic-level insight, I design next-generation catalysts for applications in water electrolysers that can enable green hydrogen production on a large scale.

One of the most exciting aspects of research is that my days are varied. Outside the laboratory, I work on data analysis, facilitate discussions of research projects in small groups, draft manuscripts to communicate my results to the wider scientific community and mentor several students. I’m also fortunate to have the opportunity to travel to present my work at conferences and collaborate with researchers at other universities!