Friday, 9 March 2018

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
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.

Friday, 2 February 2018

EAM18 - Orlando, Florida

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:

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.

Tuesday, 9 January 2018

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.

Thursday, 21 December 2017

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].


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)

Friday, 3 November 2017

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 (Zr1-xYxO2-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: [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: [Accessed: 30-Oct-2017].
[6]          Rolls-Royce, “Rolls-Royce grows global fuel cells capability with US acquisition – Rolls-Royce.” [Online]. Available: [Accessed: 02-Nov-2017].
[7]          Bloomenergy, “Fuel Cell Energy - Solid Oxide Fuel Cells SOFC | Bloom Energy.” [Online]. Available: [Accessed: 02-Nov-2017].

Friday, 6 October 2017

Sustainability of Operation Research and Management

Lucy receiving her award from the Conference Chairs,
Prof. Ying Fan and Prof. Ernesto DR Santibanez.
The Second Global Conference on The Applications of Operations Research and Operations Management for Sustainability (GCTAOS) was held from the 6th to the 8th September at Beihang University in Beijing, China.

Lucy Smith was able to attend after receiving the Research Student’s Travel Grant from the Worshipful Company of Armourers and Brasiers and present research on the life cycle assessments of high and intermediate temperature Solid Oxide Fuel Cell material structures. In addition to this, the Advance Resource Efficiency Centre, led by Prof. Lenny Koh, were able to showcase the SCEnATi (Supply Chain Environment Analysis Tool) to an international audience.

A wide range of key note speakers gave their thoughts on issues such as smart systems, relief chain management, energy investment and technology evaluation. This paved the way for an interesting collection of presentations on similar topics from other academics.

The conference was attended by academics, student and industry representatives allowing for interesting discussion and future collaboration opportunities.

Lucy was awarded the Best Paper Award, in recognition of the professional excellence of the paper for ‘Life cycle assessments and environmental profile evaluations of high and intermediate solid oxide fuel cells’ by L. Smith, F. Yang, T. Ibn. Mohammed, I. M. Reaney, D. C. Sinclair and S. C. L. Koh.

Monday, 11 September 2017

11th EUCO-TCC - Barcelona

11th European Conference on Theoretical and Computational Chemistry 3rd-7th of September, Barcelona, Spain

The central courtyard of the institute bathed in the glorious Barcelona sun.
Hosted at the Institute for Catalan Studies (IEC), in Barcelona, a majestic building built in the 17th century, the IEC, along with EuCheMS (European Chemical Services), hosted the 11th European Conference on Theoretical and Computational Chemistry.

As a computational chemist working in material science this was the perfect opportunity to network with a diverse group of researchers, who all share the same interest in simulating chemistry at the atomic level. Topics included solvation, catalysis, biochemical reactions, and material science. Given the nature of the conference there was also a focus on the techniques being developed to simulate these systems, such as density functional theory, molecular dynamics, and machine learning.

Highlights for myself included the work by Matti Hellstroem, from Georg-August-Universitat Goettingen, who works for Jorg Behler. Matti presented recent work on simulations of water and sodium hydroxide using the Behler type neural network potentials. The simulations represent how mature these methods are, though also demonstrate that there are still some hurdles to overcome. Mattis’ demonstration of the process of proton transfer through the system, and the importance of the types of clusters that form locally about sodium to enable the making and breaking of bonds.

The SnIP double helix structure
Tom Nilges from the Technical University of Munich, presented his work on the curious inorganic double helix SnIP semiconductor that have potential as a functional material. The double helices consist of  twisted chains of tin iodide (SnI+) intertwined phosphide (P–) chain. The band gap of the material, and mechanical strength, lends itself well to potential solar cell applications, and the next steps are exploring the analogues of the material.

The keynote lecture, and EuChemMS award winner, Ursula Roethlisberger, from Ecole Polytechnique Federale de Lausannae, Institut des Sciences det Ingenierie Chimiques, presented her novel work combining machine learning and computational chemistry. Primarily her work utilises DFT calculations to generate high quality, and well sampled training data, that can then lead to quick hits for discovering molecules with ideal properties. I also took the time to chat to her regarding her work on simulating MALI and related photovoltaic materials, and how she is using machine learning to search the structure space of these materials.

Overall the conference was an excellent opportunity to connect with fellow computational chemists, some who are familiar faces, and to present the research from the SUbST group to a wider audience.