Overdue up date - Sustainable Functional Materials 2018, Blue Dot and more

Welcome to a long overdue update, given holidays, staff changes and PhD vivas. But we still have lots of interesting and fun news from the FMD group.

I will let Jess kick things off.

- Chris




Jess: At the beginning of what has turned out to be a long, barmy summer, members of the Functional Materials and Devices group attended the Sustainable Functional Materials conference (SFM2018). SFM2018 was co-organised by the teams behind the EPSRC funded MASSIVE and SUBST projects and the conference brought together delegates from across academia and industry, to discuss the critical issues of sustainability and materials substitution in functional materials and devices.

The two-day conference held in Weston-Super-Mare’s Grand Pier had sessions covering a range of topics including materials properties and applications, modelling and processing as well as sustainability and environmental issues. The variety of different approaches required to tackle issues of sustainability in functional materials was clear. A number of novel lab-scale manufacturing techniques and processes were presented, including bio-inspired synthesis and low temperature processing using microwaves of functional ceramics in the soles of shoes! Of course, developing these techniques into full scale industrial techniques comes with a unique set of opportunities and challenges. Talks on the impacts of extraction and refinement and the prospect of end-of-life recycling processes for products also highlighted the need for joined-up thinking when discussing “sustainability”.

Invited speakers included our own Rebecca Boston, on bio-inspired synthesis of functional oxides and Andrew Bloodworth of the British Geological Society who discussed the challenges and potential of retrieving precious metals from the 'urban mine' made up of the defunct electronics such as phones and tablets which everyone seems to keep in a drawer

The conference dinner, held on the in a restaurant just off the beach was a fantastic opportunity to discuss the days talks and watch the sun set over our conference venue. Having grown up not far from Weston-Super-Mare it didn’t feel right being on the Grand Pier and not play in the arcade. By Wednesday lunchtime the temptation was just too much and a few “big kids” spent 10 minutes of lunch on the penny falls before the final session of talks.

All in all, SFM2018 was a really interesting and enjoyable conference, providing food for thought on a wide range of sustainability issues within the functional materials and devices sector and we are certainly looking forward to the next event in 2020 – who knows which underrated, shabby-chic seaside town we’ll visit next?!

Chris: Meanwhile at the Blue Dot Festival, other than listening to the distinctive Gary Numan, I was demonstrating materials science principles to kids and parents, including the popular "Chocolate Toughness" Charpy Test, as part of the Henry Royce Institute.

Blue Dot Festival is a world renowned music and science festival, aimed at inspiring young minds, and demonstrating the importance of the science performed world wide, while also listening to some great music.

But rather than listen to me, listen to my colleagues from the Henry Royce Institute explain the importance of our presence at the Blue Dot Festival.

The massive Lovell space telescope

Chris showing some budding scientists how chocolate

is just materials science!

Also we have said goodbye to FMD group members as Whitney Schimdt moves on to pastures new as an assistant professor at Oregon State University. We also say goodbye to Robyn Ward, who completed her PhD which involved atomistic simulations of perovskite materials, as she moves to Japan and the Nakayama group.

Pint of Science + SFM2018

Monday the 14th is when the FMD group is at Pint of Science. Taking place at the Hallamshire House in Sheffield, under the theme of "Atoms to Glaxaies: We have and energy crisis!", Dr Chris Handley will be giving a presentation on the important role of chemical simulation in materials discovery and design.






This event, along with others, is open to the public, but tickets are running out fast.

Not only will Chris be giving a presentation, but he along with a team of PhD students, will be giving some hands on demonstrations on the topic of crystal structure, simulation, and material design.

Following on from the success of the inaugural SFM conference held in April 2016 in Scarborough, the second edition of the biennial Sustainable Functional Materials conference will continue to focus on the issues around maintaining an environmentally friendly, sustainable and economically viable functional materials and device industry.

Topics will include: 

• piezoelectrics
• thermoelectrics 
• energy harvesting 
• functional properties and characterisation 
• devices 
• sustainability and risk 
• scale-up of processing and manufacturing techniques. 

SFM2018 is co-chaired by Robert Dorey at the University of Surrey and Ian Reaney at the University of Sheffield. The conference will be of interest both to industrialists and to academic researchers aiming to gain an understanding of the materials substitution and sustainability issues likely to become critical over the next decade for the functional materials and devices industry.

Invited speakers include University of Sheffield FMD member, Dr Rebecca Boston, who will be presenting her research on bio-templating for low energy materials synthesis.

Women in STEM - Cafe Scientifique and SheFEST

In the run up to International Women's Day, Cafe Scientifique and SheFEST jointly organised a "Women in STEM" special, where female postgraduate researchers from the University of Sheffield gave brief presentations on a wide range of topics.

Events like this are important for promoting diversity and inclusivity, and highlighting the contributions women have made in fields which have been typically - and still are - male dominated. The hope is that events like this also inspire the scientists of tomorrow, while also highlighting the progress still required to make a career in STEM for women more attractive.

Robyn Ward talks about ceramics that

other than plates and cups!

The department of Materials Science and Engineering is proud to hold an Athena SWAN Silver Award, and for this event was represented by two women postgraduate researchers, one of whom is also a member of the FMD group.

Robyn Ward, a doctoral researcher within the FMD group, gave a brief overview on the important role computational simulations play in enhancing our understanding of the atomistic processes that underpin the properties of functional materials, in particular ceramics, which are ubiquitous within the electronics industry.

Stavrina suggests that making the perfect

HEA is much like making the perfect

sausage

Stavrina Dimosthenous is a doctoral researcher within the department's metallurgy group. Her talk introduced the audience to the topic of High Entropy Alloys (HEA), and the potential benefits they could bring. However, just as with ceramic materials, the challenge is to use computational simulations to enable the rapid discovery of novel materials.

Also speaking at the event was Natasha Ellison, a doctoral researcher from the School of Mathematics and Statistics, giving her talk on the topic of mathematical modelling to enable a better understanding of animal movement in natural environments and how human activity can influence these patterns.

Stavrina, Robyn, Natasha and 

Fanny takes questions from the

audience and share their experiences

as women in STEM.

Fanny Stevance, a doctoral researcher in Physics and Astronomy, presented her work on understanding supernovae, and the different versions of these events that are the mechanism for the creation of the plethora of atoms that make up the Periodic table.

A common thread that tied all the talks together, it was that of mathematics, and how it is a tool to understand the world around us at different scales: be it atoms, crystal structure, animal migration and territories, or searching space for supernovae.

EAM18 - Orlando, Florida

A motley crew of scientists, from left to righ: (front row) Derek Sinclair,

Rebecca Boston, Colin Freeman, Ian Reaney, Lenny Koh,

Sinan SG El-Faouri, (middle row) Richard Veazey,

(back row) Whitney Schmidt, Carl Kennedy,

Shunusuke Murakami, James Heath.

Postdoc researcher, James Heath, updates us on the FMD trip to Orlando!

The Sheffield FMD group was well represented at the recent electronic and advanced materials (EAM18) conference in Orlando, Florida. A delegation of eleven, ranging from PhD students to professors delivered over 9 talks and several posters.

EMA is a great conference to attend if you are researching in the functional oxides/electroceramics field. There were symposia dedicated to characterisation, sustainability, processing, modelling, specific applications and much more. Information on this years content can be found here:

http://ceramics.org/eam2018


We arrived in unusually cold weather for Florida at this time year. Although 16 degrees was somewhat an improvement compared to back in Sheffield. The great disappointment of not being able to board the Disney Magical express from Orland international airport was quickly erased by beer and food at hotel, with everyone ready for the conference commencing the next day.

Roger De Souza kicked off the conference with plenary talk on “Using transport studies to reveal the myriad secrets of SrTiO3”. Some amusing commentary on the existence of a perfect single crystal and under what circumstances referring to someone as a defect is in fact a complement. This stems from a joke native to our field “people are like crystals; their defects make them interesting”. Try telling that one at the pub…

Not quite Sheffield, but it will do!

Can't have you thinking we didn't do some science too! Whitney gives her talk

Thousands of miles from home and they go to an English style pub!

Several other key features of the conference included lunchtime tutorials for the students, a session of tutorials on Wednesday evening (one given by our own Derek Sinclair) and the final part of the conference: a symposium on learning from failure. The failure talks were highly amusing and perhaps comforting that some of the more established members of our scientific community make mistakes too. Lessons learned from this symposium include:

· Don’t try cutting carbon fibre with a laser.

· If attempting to publish your work in a pure science journal call your ceramic material a poly-crystalline material instead.

· You may need to go back to basics is you have found a really good ferroelectric material that also has a cubic crystal structure.

Done Sheffield proud!

Personal highlights from the conference include some phase field modelling of ferroelectric domains [1] and grain growth [2]. There were also some interesting impedance studies on degradation of dielectric materials and in-situ x-ray diffraction studies on flash sintering [3]. Talk titles are given as references. During the conference dinner the Sheffield group got a pleasant surprise when Richard Veazey was awarded 1st prize for the student talk competition. Well done and congratulations to him.


All in all, a great conference. Many thanks to the American Ceramics Society for organising the event and the SUBST grant for funding the travel. I recommend EAM (now EMA) to anyone working in a relevant field.


1. (EAM-ELEC-S7-002-2018) New developments in Ferret, an opensource code for simulating complex behavior of electroactive materials at mesoscale J. Mangeri; L. Kuna; K. Pitike; P. Alpay; O. Heinonen; S. Nakhmanson.

2. (EAM-BASIC-S1-006-2018) A Framework to Study Heterogeneous Factors that Influence Grain Growth (Invited) D. Lewis; A. Baskaran

3. (EAM-BASIC-S2-003-2018) Flash Sintering of a Two- and Three-Phase Composites Constituted of Alumina, Spinel, and Yttria-Stabilized Zirconia D. Kok; E. Sortino; D. Yadav ; S. J. McCormack; K. Tseng; W. M. Kriven; R. Raj; M. Mecartney.

N8 Materials Modelling Meeting - York

The Annual N8 HPC/CCP5/UKCP, "New Horizons in Atomistic Simulations", one day network meeting, at York brought together experts in quantum and atomistic simulations of materials.

Predicted TEM diffraction pattern for Methylammonium Lead Iodide

Robyn Ward, presented her recent work, in collaboration with Christopher Handley, Colin Freeman, and John Harding, on the prediction of rare earth element dynamics within perovskite materials, and the prediction of transition electron spectra, and the determination of the magnitude and phase of the octahedral tilts in these simulations. This work is significant as it now allows us to connect simulation to experimental spectra, and offer insight into the atomic scale dynamics of these materials which is not seen by the experimental analysis techniques. 

Keynote presentations included:

Andrew Morris, from the Department of Metallurgy and Materials at the University of Birmingham presented his work on Ex nihilo Discovery and Design of Energy Materials. In particular Andrew focused on the use of computers to design new battery materials, and the use of quantum mechanical simulations to predict materials for the task rapidly. The challenge he presented is how to rapidly screen material structures and determine by simulation their battery properties (voltages and energy density). In particular Andrew makes use of AIRSS, ab initio random structure searching, which allows him to find the optimal crystal structure for a given stoichiometry for a novel material.

Steve Parker, from the University of Bath, presented his work on the atomistic simulation of interfaces. His main focus was on the role and composition of the interfaces in energy materials, and the mechanisms of thermal and atom transport. His simulations utilised both force fields and quantum mechanics to perform multiscale modelling. Using these methods he demonstrated the ability of simulations to predict the morphology of surfaces and in turn nano-particles. One important issue was the influence of impurities upon oxygen diffusion across grain boundaries. This is relevant to improving the lifetime of the nuclear fuel uranium dioxide. A future challenge is to investigate the heterointerfaces which are significant when we consider capacitor materials that form a core-shell structure.

Dominik Jochym, from the STFC Rutherford Appleton Laboratory presented some exciting work on computational Muon-Spin simulation by Density Functional Theory. Muons allow for the probing of the electron density and spin states, and for probing the magnetic fields of novel materials. The capability of predicting from ab initio such spectra opens up new avenues for understanding the local chemistry of materials and how we might design materials for future technological challenges.

Cold Sintering Processing - What is it?

PhD Student Sinan Faouri briefly gives us an overview of Cold Sintering Processing, a novel technique for the processing of functional materials that addresses the energy cost of manufacturing these materials.

Sintering is a thermal treatment process of forming a dense bulk solid material by heat or pressure before reaching its melting point [1,3]. The conventional sintering process is a high temperature sintering method where powders are heated between 50-75% of melting temperature to > 95% theoretical density [2]. Heating the starting materials to high temperatures facilitates the motion of atoms, enabling the homogenisation of the bulk solid [5].

Cold sintering processing (CSP) is a novel technique developed recently to achieve dense ceramic solids at extremely low temperatures ( < 180 ℃ ). across a vast variety of elements and composites [3]. The process includes using aqueous-based solutions (eg: water) as transient solvents to aid densification by a non-equilibrium mediated dissolution–precipitation process [4].

In order to provide a good environment and conditions for precipitation and recrystallization in hydrothermal reactions, a convenient aqueous solution should be chosen carefully which will be also significant in reducing sintering temperature [5].

To achieve densified bulk materials, some additional characteristics to the pre-dominance diagrams are used when studying CSP effective factors as shown in figure (1) [5].

    

Figure 1: Flowchart summary of CSP stages

Figure (1) shows a flowchart for the possible roots of CSP from particle rearrangement to densification. The internal characteristics that affect CSP are the material’s composition, crystal structure, particle size and solubility in water [5]. Some of the physical variables determining the kinetic processes for mass transport are the hot press pressure, sintering temperature, time of sintering, the rate of heating, and the atmosphere pressure [5]. Preparing a convenient aqueous solution is also critical as some other significant factors to CSP include the nature of the solute, the concentration of the solute and pH value. The latter can be studied via pre-dominance diagrams [5].

The dissolution nature plays a significant role in determining whether densification will eventually occur or not. If the materials dissolve equally with ease, a direct and simple CSP is possible, since the surface of material can be easily dissolved in water with a homogenous chemical stoichiometry [5]. However, no densification will occur if one material dissolves more easily that the other. This is because one material will form a passive surface [5]. Negligible dissolution can work well in CSP if a saturated solution is added that targets the chemical compounds of the material to be densified [5].

The next steps in CSP are evaporation of the liquid, the hydrothermal crystal growth (in the case of water as a solvent) or formation of a glass/intermediate phase, and eventually grain growth and densification or recrystallization of a glass where it gets ejected as shown in CSP flowchart in figure (1) [5].

References

1.       https://en.wikipedia.org/wiki/Sintering

2.      Dr. Jing Guo, Dr. Hanzheng Guo, Amanda L. Baker, Prof. Michael T. Lanagan, Dr. Elizabeth R. Kupp, Prof. Gary L. Messing, Prof. Clive A. Randall. Cold Sintering: A Paradigm Shift for Processing and Integration of Ceramics. Volume 55, Issue 38 September 12, 2016. Pages 11457–11461

3.      Hanzheng Guo, Jing Guo,  Amanda Baker, and Clive A. Randall. Hydrothermal-Assisted Cold Sintering Process: A New Guidance for Low-Temperature Ceramic Sintering. ACS Appl. Mater. Interfaces 2016, 8, 20909−20915

4.      Jing Guo, Amanda L. Baker, Hanzheng Guo, Michael Lanagan, and Clive A. Randall. Cold Sintering Process: A New Era for Ceramic Packaging and Microwave Device Development.  J. Am. Ceram. Soc., 1–7 (2016)

5.      Hanzheng Guo, Amanda Baker, Jing Guo, and Clive A. Randall. Cold Sintering Process: A Novel Technique for Low-Temperature Ceramic Processing of Ferroelectrics. J. Am. Ceram. Soc., 1–19 (2016)

Energy of the Future - Solid Oxide Fuel Cells

FMD PhD student, Julia Ramirez Gonzalez gives us an overview of how Solid Oxide Fuel Cells operate and the importance of such materials in meeting future energy production challenges.

Can you imagine our daily life without electricity? Maybe we can deal with it for a couple of hours, but this commodity has become one of the engines of our generation [1]. Nevertheless, the environmental implications of producing energy by fossil fuel combustion, is the driving force to look for more efficient and environmentally friendly alternatives of electricity generation.

Fuel cells are one of the alternatives. These devices generate electricity by an electrochemical reaction of gaseous reactants. One of the reactants is the oxygen in the air, and the other is hydrogen or a hydrocarbon [2]. The configuration of this devices resembles a sandwich. It has two electrodes, one in contact with fuel (anode), and the other in contact with oxygen (cathode): These two interfaces are separated by and electrolyte. There are many types of fuel cells, which are classified by its type of electrolyte, such as polymer electrolyte membrane (PEM), alkaline (AFC), phosphoric acid (PAFC), molten carbonate (MCFC), and solid oxide (SOFC) [3]. Each type differs in its operation temperatures, useful fuel, efficiency and therefore its applications.

Research on SOFC showed that these materials can work with higher hydrocarbons, giving them the advantage of fuel flexibility. And the most important feature is that all of its components are solid, which avoids the risk of spillages, gives it the freedom for stacking configuration, and it is a quiet system as it does not have any moving parts [2][4] . 

But how does it work? On one side of the cell there is a high concentration of oxygen and on the other side there is none. An electrical potential gradient across the electrolyte is built up. However, the electrolyte does not allow electrons or gas to flow through, but its crystal structure has oxygen vacancies, which allows the migration of oxygen ions. Therefore, at the three-phase boundary, cathode-electrolyte-air, oxygen will be reduced, by obtaining electrons from the cathode [2], Equation 1. 

Eq. 1

Thus, oxygen ions can hop through the electrolyte and can reach the anode-electrolyte-fuel boundary, where the fuel oxidizes; where the products will be steam and electrons, Equation 2 [2].

Eq. 2

If the anode and cathode are connected by an external circuit, the cycle is repeat again as long as the two gases are present, and this is how electricity can be harvested through the external circuit. As shown in the video. 

These devices operate in the temperature range between 500-1000°C, which adds challenges to the material requirements. The materials need to have chemical stability, to avoid reaction with the reactants, a similar thermal expansion coefficient, to reduce the possibility of cracks during cycling; strength and toughness, no one likes a broken device; but also, it has to be easy to fabricate and have a low cost [4].

As you can see there are many requirements, but material scientists like these challenges and have come up with several options.

Yttria-stabilised zirconia is the most widely used as an electrolyte, which is zirconia doped with yttria (Zr_1-xY_xO_2-x/2; x: 0.08). It can also be doped with calcium oxide, magnesium oxide, scandium oxide, neodymium oxide and ytterbium oxide. In addition, cerium oxide doped with samarium (SDC), gadolinium (GDC), and calcium (CDC); lanthanum gallate; bismuth yttrium oxide; barium cerate and strontium cerate, can be also used. The reason of the high operation temperatures of these devices is to promote the oxide ion conduction within the electrolyte [4].

Both electrodes have to be able to distribute the hydrogen and oxygen respectively, serve as catalysts and allow the flow of electrons. Therefore, the anode is a porous ceramic-metallic composite. The metal provides the electronic conduction pathway for the electrons, the ceramic made from the same material as the electrolyte assures a similar thermal expansion coefficient and good compatibility. The popular choice is Ni-YSZ, but there is also Ni-SDC and Ni-GDC [4]. 

For the cathode also a porous structure to allow the flow of gas usually made from a perovskite-type lanthanum strontium manganite (LSM), and lanthanum calcium manganite (LCM); also provides a similar thermal expansion. It is been discovered that by making a composite of perovskite and electrolyte increases the active sites for the electrochemical reactions [4]. 

These electricity generation systems have many possibilities and applications. It can be used as a combined heat and power plant, distributed generation, but also used in remote areas as the generation can be at the point of consumption, reducing the transmission costs. It has an efficiency of ~60% [3]. From an environmental point of view the CO2 emissions will be considerable reduced, Mike Manson an expert in SOFC from Manchester said to The Guardian that a 35% reduction in CO2 emission could be possible using this technology, comparing it with consuming electricity from gas power plant and hot water from a boiler [5]. There is also the idea of a hybrid/gas turbine cycle, to take advantage of the high temperatures of the existing power plants [3]. There are many companies that see the potential of this technology and have and R&D area dedicated to it, as Rolls-Royce and Bloomenergy [6][7]. 

In summary, SOFC are a great alternative for the generation of electricity, further research needs to be done to reduce its operations temperatures, but it represents a step closer to a greener electricity technology era.

[1]          “Key world energy statistics,” Int. Energy Agency, 2017.

[2]          R. J. Kee, H. Zhu, and D. G. Goodwin, “Solid-oxide fuel cells with hydrocarbon fuels,” Proc. Combust. Inst., vol. 30, pp. 2379–2404, 2005.

[3]          D. of Energy, “Comparison of Fuel Cell Technologies | Department of Energy.” [Online]. Available: https://energy.gov/eere/fuelcells/comparison-fuel-cell-technologies. [Accessed: 01-Nov-2017].

[4]          A. B. Stambouli and E. Traversa, “Solid oxide fuel cells (SOFCs): a review of an environmentally clean and efficient source of energy,” Renew. Sustain. Energy Rev., vol. 6, pp. 433–455, 2002.

[5]          D. Clark, “Manchester Report: Ceramic fuel cells | Environment | The Guardian,” The Guardian, 2009. [Online]. Available: https://www.theguardian.com/environment/2009/jul/13/manchester-report-fuel-cells. [Accessed: 30-Oct-2017].

[6]          Rolls-Royce, “Rolls-Royce grows global fuel cells capability with US acquisition – Rolls-Royce.” [Online]. Available: http://www.rolls-royce.com/media/press-releases/yr-2007/rr-grows-global-fuel-cells.aspx. [Accessed: 02-Nov-2017].

[7]          Bloomenergy, “Fuel Cell Energy - Solid Oxide Fuel Cells SOFC | Bloom Energy.” [Online]. Available: http://www.bloomenergy.com/fuel-cell/solid-oxide/. [Accessed: 02-Nov-2017].