Begbroke Science Forum

The Begbroke Science Forum was established to create an environment at Begbroke for scientists with different backgrounds who have an interest in interacting with colleagues from this or other Departments, University, Industry, etc. and who would not normally meet at conferences. The Begbroke Science Forums are held as opportunities arise. When possible they are held on Fridays between 1.00-2.00 pm. (Convenor: Professor Nicole Grobert)

Venue: Begbroke, Oxford Room
Time: 1.00-2.00 pm

**Travel arrangements**
Minibus departs Materials Department (Parks Road) at 12:31 arriving at Begbroke Science Park at 12:50 – perfect for this talk. For the return journey a minibus leaves Begbroke at 14:25 arriving at Parks Road at 14:40.

May 2015

Friday, 29.05.2015, 1.00-2.00 pm
Metrology for Graphene as an Industry Enabler

Dr Andrew Pollard (National Physical Laboratory (NPL))

As the UK’s leading National Measurement Institute (NMI), the National Physical Laboratory (NPL) is uniquely positioned to enable the global emerging graphene industry through the application of metrology in this area, bridging the gap between academia and industry. With measurement capability and expertise in a wide range of scientific areas, the combined and complementary approach of varied characterisation methods for structural, chemical, electrical and other properties, allows the real-world challenges of commercialising graphene and other 2-D materials to be addressed. Metrology challenges such as new measurement techniques, quantitative characterisation and the understanding of artefacts must be overcome in this area through cross-disciplinary research and collaboration with both academia and industry. These challenges and how they relate to the characterisation of the structural and chemical properties of graphene and related 2-D materials via techniques such as Raman spectroscopy, tip-enhanced Raman spectroscopy (TERS), secondary ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS), scanning tunnelling microscopy (STM) and scanning electrochemical microscopy (SECM) will be discussed.

Short Bio Andrew is leading the Surface and Nanoanalysis Group's research into the measurement of graphene, other graphene-related 2-D materials, and associated devices. This metrology research focuses on the actual measurement of the materials with a range of surface characterisation techniques, such as Raman spectroscopy and tip-enhanced Raman spectroscopy (TERS), scanning probe microscopies (SPM), secondary ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS) and ellipsometry. Andrew is also heavily engaged with organisations in the emerging graphene industry, advising on aspects of standardisation and measurement in this area, and is on the Advisory Board of several different graphene organisations.

Friday, 08.05.2015, 1.00-2.00 pm
Atomic Resolution Electron Microscopy of MoSe2/WSe2 heterojunction

Dr Ana Sanchez (Department of Physics, University of Warwick)

While graphene is the most studied two-dimensional (2D) material, atomically thin layered transition metal dichalcogenides (TMDs) have recently emerged as a new class of 2D nanomaterials. Due to their band structure, monolayers of direct band gap semiconducting TMD have promise to complement the zero bandgap energy of graphene, offering an extensive range of applications in electronics and optics. The dichalcogenide heterojunctions were grown by physical vapor transport. Lateral heteroepitaxy was visible in an optical microscope and the structures showed enhanced photoluminescence. Atomically resolved transmission electron microscopy using a doublecorrected ARM200F (80-200kV) revealed that the MoSe2/WSe2 heterojunction is an undistorted honeycomb lattice in which substitution of one transition metal by another occurs across the interface [1]. There were no dislocations or grain boundaries, i.e. an atomically seamless MoSe2/WSe2 semiconductor junction was achieved. Moreover, strain mapping of atomic resolution images demonstrates negligible distortion at the heterojunction, and the analysis of the different atomic species demonstrates that the interface has a finite width similar to 3D heterojunctions. Vertical stacking of MoSe2/WSe2 bilayers was also analyzed using electron microscopy. An analysis of the intensity in annular dark field images shows that Se atoms of the WSe2 layer align with the Mo atoms of the MoSe2 layer in some of these heterojunctions. We expect that the growth of these lateral junctions will open new device functionalities, such as in-plane transistors and diodes integrated within a single atomically thin layer [1,2,3]. [1] C. Huang et al. Nat. Mater. 13 (2014) 1096 [2] Y. Gong et al, Nat. Mater. 13 (2014) 1135 [3] G.S. Duesberg Nat. Mater. 13 (2014) 1075

Short Bio Ana Sanchez is Principal Research Fellow at the University of Warwick. Her research interest are based on the developments in the field of advanced transmission electron microscopy techniques and materials characterization, mainly in the areas of semiconductors (including 2D dichalcogenides) and oxide materials.

February 2015

Friday, 27.02.2015, 1.00-2.00 pm
Van der Waals epitaxy in growth of and on two dimensional materials

Prof Neil Wilson (Physics department, University of Warwick)

For most electronic and optoelectronic applications, achieving high performance materials requires their growth in thin film but crystalline form. Usually epitaxial growth is used to achieve this, through strong chemical bonds between a crystalline substrate and the growth material. These bonds define the atomic arrangements locally as the film grows, requiring a close lattice match between substrate and epitaxial layer. The design rules for such hetero-epitaxial processes are now well understood, to the extent that the strong interactions can be used to intentionally engineer strain in layers, and control dislocations and other defects.

However, for some materials there are no dangling bonds at the surface; in this case growth can proceed with only weak interactions between the substrate and growth layer. Interestingly this can still produce highly crystalline materials and the growth can still be epitaxial, in that the orientation of the growing layer can still be defined by the substrate. Such van der Waals epitaxy is increasingly important for the growth of layered two-dimensional materials, but is also of relevance for molecular materials, e.g. for organic electronics, and offers the potential to grow a range of materials not easily grown by conventional epitaxy and at lower cost. However, it is much less well understood, in part because the length scales of the interactions are much longer.

I will present some of our recent results on the growth of graphene and hexagonal boron nitride on copper and explain how van der Waals epitaxy results in long range order in both, despite the large differences in lattice parameter and the differences in symmetry between substrate and growth layer. Surprisingly, the epitaxial nature of the growth does not always result in ordering along the high symmetry axes of the substrate, indicating that this is a long range effect that is qualitatively different to conventional epitaxy. Similar effects can be seen in the growth and self-assembly of molecular thin films on graphene, as we observe by molecular resolution imaging by aberration corrected electron microscopy and scanning tunnelling microscopy.

Short Bio Dr Neil Wilson is an Associate Professor and member of the Microscopy Group in the Department of Physics, University of Warwick. Neil’s research interests are in the synthesis of nanomaterials and the development and application of microscopy techniques to characterise them. He has a PhD in Physics from Warwick, an MS in Physics from the University of Pennsylvania and an MSc/MA in Natural Sciences from Pembroke College Cambridge.

Friday, 06.02.2015, 1.00-2.00 pm
Sustainable Carbon Materials and Chemicals from Biomass Hydrothermal Processes

Prof Magdalena Titirici (Department of Engineering and Materials Science, Queen Mary University of London)

The creation of new and very importantly greener industries and new sustainable pathways are crucial to create a world in which energy use needs not be limited and where usable energy can be produced and stored wherever it is needed.

New materials based on carbon, ideally produced via inexpensive, low energy consumption methods, using renewable resources as precursors, with flexible morphologies, pore structures and functionalities, are increasingly viewed as ideal candidates to fulfil these goals. The resulting materials should be a feasible solution for the efficient storage of energy and gases.

Hydrothermal carbonization [1] is an ideal technology for the production of such low-cost but highly performing materials out of the most abundant renewable resource on the planet, i.e. lignocellulosic biomass. The practical approach is very simple and consists in placing a biomass precursor inside an autoclave, in water, followed by hydrothermal treatment overnight at 160-200°C. Since the production of carbon materials in general implies harsher and multi-step methodologies along with fossil –based precursors, this process has clear advantages in terms of sustainability and cost.

Here, I wish to present some of our latest results on the production and characterization of nanostructured hydrothermal carbons (HTC) and their use in renewable energy related applications, [2], [3]. I will also present some results on the use of HTC as well as heterogenous catalysts to convert levulinic acid obtained in the liquid phase after biomass hydrothermal treatment into other platform chemicals such as levulinate esters or gamma-valerolactone [4].

[1] M.-M. Titirici, R. J. White, C. Falco, M. Sevilla, Energy & Environmental Science 2012, 5, 6796-6822. [2] K. Tang , L. Fu , R J. White , L. Yu , M. Antonietti , J. Maier, M. M. Titirici , Adv. Energy Materials, 2012, 2, 873–877 [3] N. Brun, S. A. Wohlgemuth, P. Osiceanu, M. M. Titirici, Green Chem., 2013, 15, 2514-2524 [4] F. Pileidis, M. Tabassum, S. Coutts, M. M. Ttitirici, Chinese Journal of Catalysis, 2014, 35, 929–936

Short Bio Magdalena Titirici obtained her PhD at the University of Dortmund, Germany in 2005. Between 2006–2012 she led the group ‘‘Sustainable Carbon Materials’’ at the Max Planck Institute of Colloids and Interfaces, Potsdam, Germany where she also did her ‘‘Habilitation”. In 2013 Magda became an Associate Professor in Materials Science Queen Mary University of London. She was promoted to a full Professorship in Sustainable Materials Chemistry in 2014. Prof. Titirici is the author of around 100 publications in the field of sustainable materials and green nanochemistry, several book chapters and one edited book. She is in the editorial board of ChemSusChem (Wiley) and J. Mater. Chem. A (RSC) and an associate editor for J. Mater. Chem. A. Her research interests include porous materials, hydrothermal carbonisation, innovative utilisation of biomass, CO2 sequestration, electrocatalysis in fuel cells as well as energy storage in secondary batteries and supercapacitors.

January 2015

Friday, 16.01.2015, 1.00-2.00 pm
Hybrid Materials and Composites Engineered from Metal-Organic Frameworks (MOFs)

Prof Jin-Chong Tan (Department of Engineering Science, University of Oxford)

Porous metal-organic frameworks (MOFs) and hybrid frameworks are emergent multifunctional materials that have garnered major developments in the last decade. Indeed the incredibly rich structural diversity of this new class of materials, combined with its ‘designable’ physical and chemical properties has caught the imagination of scientists, engineers and technologists from multiple disciplines. By virtue of their immense versatility and functionalities, a number of promising applications have already been proposed which are aimed at challenging industrial sectors, e.g. energy harvesting and storage, sensing and microelectronics, biomedicine, carbon capture, and environmental sustainability. In this talk, recent results associated with the design, fabrication, and characterisation to establish structure-function relationships (e.g. mechanical, electrical, rheology) of a number of MOF-based materials encompassing single crystals, nanosheets, thin-film coatings, hybrid gels and nanocomposites will be discussed.

Short Bio JC is Associate Professor of Engineering Science and Fellow of Balliol College at Oxford. He leads the Multifunctional Materials and Composites (MMC) Laboratory (, specialising in the complex thermo-mechanical and physico-chemical behaviour of hybrids, composites, and a range of nanostructured materials. JC completed his PhD at Cambridge (Downing College, 2005) in the Department of Materials Science & Metallurgy, and was a Junior Research Fellow in Wolfson College (Cambridge) before joining Oxford in the summer of 2012. He is the guest editor to the 2015’s CrystEngComm themed issue on MOFs and Hybrid Materials.

November 2014

Thursday, 27.11.2014, 1.00-2.00 pm
Two-dimensional semiconducting films in optical microcavities

Prof Alexander Tartakovskii (Department of Physics and Astronomy, University of Sheffield)

Layered metal-chalcogenides (MC) exhibit new attractive properties when cleaved into quasi-two-dimensional (2D) films. Of particular interest are transition metal dichalcogenides (TMDCs) such as MoS2, MoSe2, WS2, WSe2, which become direct band semiconductors in a form of a single monolayer. These materials exhibit very robust excitons with binding energies of around 0.3-0.5 eV, 30-50 times higher than in III-V heterostructures, and have surprisingly strong absorption of up to 30% in a single monolayer. These properties make them interesting candidates for strong light-matter interaction experiments and studies of non-linear effects in truly 2D polariton systems. Here I will present our recent results and will review fabrication of microcavities comprising semiconducting 2D films; report on observation of the Purcell effect in emission of thin GaSe and MoS2 films and demonstration of 2D polariton states in tunable optical microcavities.

August 2014

Friday, 01.08.2014, 1.00-2.00 pm
Molecularly-tailored nanomaterials and interfaces: untangling and enhancing unfavorably coupled properties

Prof Ganpati Ramanath (Rensselaer Polytechnic Institute)

Realizing novel nanomaterials and tailored heterointerfaces with control over electrical, thermal and mechanical properties is key for many applications such as electronics devices and energy harvesting. The first part of my talk will discuss the synthesis and properties of a new class of bulk doped bulk nanothermoelectric materials obtained by surfactant-directed sculpting and doping for solid-state cooling and electricity harvesting from waste heat. The second part of my talk will describe the use of single nanolayers of organic coupling agents to tailor multiple properties of soft-hard or organic-inorganic heterointerfaces germane to emergent nanoelectronics devices. I will demonstrate a scalable microwave-solvothermal approach to sculpt nanocrystals with controllable shape, size, trace doping and surface chemistry. Bulk pellets made from these nanocrystals exhibit multifold superior figures of merit than their non-nanostructured and non-alloyed counterparts. While nanostructuring leads to ultralow thermal conductivities, doping-induced alterations in defect chemistry and electronic band structure of the materials lead to high electrical conductivities and high Seebeck coefficients. Atomistic and electronic structure level property enhancement mechanisms will be discussed based upon a variety of microscopies, spectroscopies, and density functional theory calculations. I will then describe how interfacial nanolayers of coupling agents with suitably chosen termini are attractive for tailoring the chemical, electrical, mechanical and thermal properties of heterointerfaces. I will demonstrate multifold enhancement in electrical stability, mechanical toughness and thermal conductance by understanding and manipulating the interfacial bond chemistry using molecular nanolayers. I will conclude by discussing the property interrelationships, the enhancement mechanisms, and the utility of using nanomolecular layers to access atomistic details of nanoscopic interfacial phenomena via macro-experiments. Selected references: Nature Materials 12, 118 (2013); Nature Materials 11, 233 (2012); Nano Lett. 12, 4523 (2012); Nano Lett. 11(10), 4337 (2011); ACS Nano 4, 5055 (2010); Nano Lett. 10, 4417-22 (2010); Nature 447, 299 (2007); Phys. Rev. B. 83, 035412 (2011); Appl. Phys. Lett. 99, 133103 (2011); Appl. Phys. Lett. 99, 133101 (2011); ACS Appl. Mater. Interf. 2(5), 1275 (2010).

Short Bio Ganapti Ramanath is John Tod Horton Professor of Materials Science and Engineering at RPI. He received his PhD from the University of Illinois, Urbana, in 1997. His PhD thesis work won him a Graduate Student Gold Award from the Materials Research Society. He joined Rensselaer in 1998 as an assistant professor and has been a full professor since 2006, and was named John Tod Horton Chaired Professor in 2013. His research is focused on developing a fundamental understanding of structure-processing-property relationships in nanomaterials and interfaces for applications in energy and electronics. He has co-authored 150+ publication articles (h-index 34-38, 4000+ citations, 26+/paper), one book chapter, and holds 9 US patents. He has delivered 170+ invited talks worldwide, and has organized several international symposia and workshops for the MRS, AVS and TMS. He has won several awards including the Friedrich Wilhem Bessel Award (2013), Brahm Prakash Chaired Professorship at IISc, Bangalore, India, NSF CAREER Award, Professor Bergman Young Scientist Award from the US-Israel Binational Science Foundation, an IBM University Research Partnership Award and Alexander von Humboldt Fellowship. Visiting appointments include RWTH, Aachen, Germany; Max-Planck-Institute for Solid State Research, Stuttgart, Germany; National Institute of Materials Science, Tsukuba, Japan; IISc, Bangalore, India; University of Wollongong, Australia. Ramanath is a Director and co-founder of ThermoAura Inc., a start-up company. He served as the Director of the NY State Center for Future Energy Systems (2008-2010). He serves as an Associate Editor of IEEE Transactions on Nanotechnology and is an Editorial Advisory Board member for Journal of Experimental Nanoscience.

July 2014

Monday, 14.07.2014, 1.00-2.00 pm
Materials for high temperature superconduction

Dr Susannah Speller (Department of Materials, University of Oxford)

Understanding the interplay between superconductivity and magnetism in iron-based superconductors is likely to provide significant insights into the elusive mechanisms responsible for high temperature superconductivity. The co-existence of magnetic order and superconductivity is a common feature of the iron-based superconductors, raising the question of whether these phases are spatially distinct or whether the same electrons are responsible for both phenomena. To investigate the nature of the phase separation in Fe-based single crystals, I have employed a combination of microanalytic techniques to assess the chemical and structural uniformity of single crystalline samples used for fundamental property measurements. In particular I will discuss the use of the high resolution Electron Backscatter Diffraction (HR-EBSD) technique to map local variations in lattice parameter with exceptional precision and sub-micron spatial resolution for a range of different iron-based compounds including Fe(Se,Te) and AFe2Se2 (A=Cs,Rb) . In AFe2Se2, the intrinsic phase separation is very extreme, with significant differences in chemical composition, crystal structure and electronic struct ure associated with the spatially distinct electronic phases. Here I will report recent results on the microstructural evolution in AFe2Se2 single crystals on annealing, and how this influences the electronic structure and superconducting/magnetic properties. In addition, I will briefly outline the other diverse research activities being undertaken in my group, ranging from TEM studies on topological insulators to fabricating superconducting joints for high field magnets.

Short Bio Susie Speller is a Lecturer and Royal Academy of Engineering/EPSRC Research Fellow Oxford Materials. Susie’s research interests centre on the relationships between processing, microstructure, and properties of superconducting materials. This includes the growth and advanced characterisation of novel iron-based superconductors in thin film form as will be discussed in her talk, as described below.

Friday, 04.07.2014, 1.00-2.00 pm
Nanotechnology for Medicine: Challenges and Opportunities

Dr Sonia Trigueros (Co-Director of the Oxford Martin Programme on Nanotechnology Academic Fellow at Physics Department. Oxford University)

Nanotechnology is a new exciting field that has the potential to transform the way that medical and healthcare solutions are being developing. At the Physics Department we research on the newest techniques and materials at the nanoscale level. We apply this knowledge directly first to learn the relevant biology at the single molecule level and then apply the science and the technology to solve the most pressing medical problems of the 21st century. The talk will be focus on my current projects, the impact that nanotechnology has in the advance of medicine and regulatory concerns arise from some new nano-products already on the market. There is need to bridge the gap from experimental science to product regulation to ensure a safety progress in this area and achieve the future needs of Medicine.

Short Bio Sonia Trigueros’ research focuses on the design of novel nanostructures to target DNA biomolecular motors and DNA conformational states in dividing cells, specifically cancer cells. She is also developing new Nanomedicines to tackle bacterial antibiotic resistance problem. She has a PhD in molecular biology from IBMB-CSIC and Universidad de Barcelona. After her postdoctoral research fellowships at Harvard and Oxford Universities, Trigueros was a research visitor to several academic institutions including NIH-Washington and Havana University. She is currently Academic Fellow at the Physics Department and the co-director of the Oxford Martin Institute of Nanoscience for Medicine at University of Oxford.

Wednesday, 02.07.2014, 11:00–12:00
First-principles structure prediction of interfaces

Dr Georg Schusteritsch (University College London)
I will present the ab initio random structure searching (AIRSS) method and how it can be used to predict the structure of interfaces. A detailed understanding of and ability to predict the atomic structure of interfaces is of crucial importance for many technologies. Interfaces are however very hard to predict due to the complicated geometries, crystal orientations and possible non-stoichiometric conditions involved. Our method relies on generating random structures in the vicinity of the interface and relaxing them within the framework of density functional theory (DFT). The method is simple, requiring only a small set of parameters that can be easily connected to the physics of the system of interest, and efficient, allowing for high-throughput first-principles calculations on modern parallel architectures. Examples for two interfaces will be presented here, grain boundaries in graphene and grain boundaries in strontium titanate (STO). We find previously unknown low energy interface structures for both the graphene and STO system. The atomic structure of these grain boundaries will be discussed and compared to the previously known higher energy structures.

Short Bio Georg Schusteritsch is a postdoctoral research associate in the Department of Physics and Astronomy at University College London. His research focuses on Condensed Matter theory and Materials Physics. He uses first-principles methods to study the properties of materials, with a particular focus on materials discovery and structure prediction of defects in materials of technological importance such as nanomaterials, semiconductors, and transition metal oxides. He holds a PhD and AM in Applied Physics from Harvard University and an MRes and MSci from the Department of Chemistry and Department of Physics at Imperial College London.

**Travel arrangements**
Minibus departs Materials Department (Parks Road) at 10:31 arriving at Begbroke Science Park at 10:50 – perfect for this talk. For the return journey a minibus leaves Begbroke at 12:10 arriving at Parks Road at 12:30.

June 2014

Friday, 20.06.2014, 1.30-2.30 pm
Graphene-based 2D and 3D multifunctional structures

Dr Cecilia Mattevi (Department of Materials, Imperial College London)

Graphene has the potential to form novel platforms for a wide range of multifunctional systems encompassing two-dimensional devices and three-dimensional strong, lightweight porous materials. The challenge is to fabricate graphene 2D and 3D structures in practical dimensions with an accurate control of the chemistry and architecture maintaining the intrinsic properties of graphene. We present new wet processing techniques to generate ultra-light cellular networks of graphene with controlled structural arrangements from the nano to the macro level and new insight into the 2D assembly of graphene and inorganic atomic layer materials. We demonstrate electrically conductive ultra-light (ρ≥1 mg cm-3) cellular networks made by chemically modified graphene with versatile mechanical response (elastic-plastic to elastomeric, reversible deformation, high energy absorption) and organic absorption capabilities (above 600 grams per gram of material) [1]. The approach used for the fabrication of these highly porous cellular networks enables the effective structural control needed to guide the design of practical devices. With the objective of realizing 2D heterostructures of graphene, we have studied the epitaxial growth of graphene on copper foils from the early stages of nucleation. This is a complex process, influenced by thermodynamic, kinetic, and growth parameters, often leading to diverse island shapes. Using a phase-field model we have been able to provide a unified description of these diverse growth morphologies and compare the model results with experimental evidences. We show that anisotropic diffusion of carbon absorbed species has a very important, counterintuitive role in the determination of the shape of islands, and we present a “phase diagram” of growth shapes as a function of growth rate for different copper facets [2]. Our results are shown to be in excellent agreement with growth shapes observed for high symmetry facets such as (111) and (001) as well as for high-index surfaces such as (221) and (310). In addition, we show that some of these growth concepts can be translated and utilized for the synthesis of large domains of atomic layers of transition metal dichalcogenides. [1] S.Barg et al. acceppted Nature Comm. 2014 [2] E. Meca et al. Nano Letters, 13, p 5692–5697, (2013).

Short Bio Cecilia Mattevi is a Lecturer and Royal Society University Research Fellow in the Department of Materials at Imperial College London, a position she has held since October 2012. Prior to moving to Imperial in 2010 Cecilia’s first post-doctoral position was in the group of Prof. Manish Chhowalla at Rutgers Univerisity, NJ, USA. She received her PhD (2008) and MSc (2004) in Materials Science from the University of Padua, IT. Cecilia’s research interests centre on the synthesis of novel 2D atomically thin materials with tuneable optoelectronic properties for light emitting devices and for highly porous 3D hierarchical structures for energy applications. These topics will also be the focus of her talk, as described below.

May 2014

Wednesday, 21.05.2014, 1.30-2.30 pm
Nanomaterials for battery technologies

Dr Mark Copley (Johnson Matthey PLC)

User and original equipment manufacturers’ requirements for higher capacity, higher power, greater durability and lower cost battery systems are constantly driving progress towards advanced battery electrode materials and electrolytes and better performing cells. The areas of nanomaterial synthesis and scale up, electrode preparation and electrochemical testing all have particular synergies with existing expertise within Johnson Matthey, hence the identification of Battery Materials as an opportunity for New Business Development and the formation of the Battery Technologies Group in 2013. A team of scientists within the Catalyst and Materials Group at Sonning are now pursuing a range of activities related to lithium batteries, with significant emphasis on the synthesis, characterisation and electrochemical testing of state of the art lithium ion materials in addition to work on Li-air and Li-S batteries. Our aim is to develop our understanding and expertise ready to support future growth within the Battery Technologies area.

Short Bio Mark Copley is a Principal Scientist at Johnson Matthey working on the development and application of nanomaterials in renewable energy. He received his PhD from University College Cork in 2005 where he continued as a post-doctoral researcher until 2008 when he joined Johnson Matthey. Since joining the company he has worked in both Emission Control Technologies in the area of process development and at the Technology Centre, focusing on projects relating to synthesis of nanomaterials via novel routes and their real world applications.

April 2014

Friday, 04.04.2014, 1.30-2.30 pm
Bioinspired ceramic materials

Prof Eduardo Saiz (Department of Materials, Imperial College London)

The idea of mimicking natural structures to create lightweight structural materials with unprecedented combinations of strength and toughness is extremely appealing and has attracted much interest over the last decade. However, so far man-made materials have failed to fully replicate two key aspects of natural composites: their unique hierarchical structures and their ability to adapt and self-repair. In this presentation we will review and compare several approaches for the fabrication of complex ceramic structures, from the bio-inspired mineralization of polymer scaffolds to the self-assembly or “smart” particles or the freezing of suspensions. Extension of these approaches to new materials such as graphene will be discussed. The goal is to compare the advantages and disadvantages of each approach with particular emphasis in their ability to manufacture complex structures in practical dimensions.

Short Bio Eduardo Saiz holds the Chair in Structural Ceramics at Imperial College, London. He received his MsC from the Universidad de Cantabria (Spain) and his PhD from the Universidad Autonoma de Madrid in 1992. His PhD project was carried out at the Instituto de Cerámica y Vidrio – CSIC. There he worked in the development of ceramic superconducting thick films. In 1992 he joined Lawrence Berkeley National Laboratory (USA) with a Fulbright fellowship and remained there as a staff scientist until 2009 when he moved to Imperial. In Berkeley he worked in the fields of high temperature capillarity, joining, composites and biomaterials. His research interests include the development of new processing techniques for the fabrication of ceramic-based composites, in particular hierarchical composites with bioinspired architectures, the study of high temperature interfacial phenomena such as spreading, and the development of new materials to support bone tissue engineering. At Imperial College, he forms part of the Centre for Advanced Structural Ceramics (CASC). He is also currently the coordinator of BioBone, an Intial Traning Network in the field of bioceramics funded inthe FP7 framework with nine academic and industrial partners.

March 2014

Friday, 28.03.2014, 1.30-2.30 pm
Using cells in culture to investigate how bone responds to implant materials

Dr Roger Brooks (Orthopaedic Research Unit, University of Cambridge)

Bone is a dynamic, living tissue with an inherent ability to repair small amounts of damage. A number of implant materials have been developed that interface with bone; these are used for joint replacement, fracture and ligament fixation and as bone graft substitute materials, to stimulate and provide a substrate for the repair of defects too large for bone to heal by itself. New materials are continually being investigated for their potential to improve on those currently in use. Cells grown in culture are used at an early stage in studies evaluating the suitability of these materials for their intended application. This lecture will ask the question; what can investigations using cultured cells really tell us about implant materials and their potential suitability for successful orthopaedic treatments.

Short Bio Dr Roger Brooks has almost 20 years’ experience working in the Orthopaedic Research Unit at Addenbrooke’s Hospital on the development of bone implant materials. He has been involved in the development of a several implants used clinically including the bone graft substitute Actifuse (Baxter), the acetabular compliant bearing MITCH (Stryker), the Cadisc® spinal disc replacement (Ranier) and Chondromimetic, an osteochondral graft for focal cartilage defects (Tigenix). He is currently a Senior Research Associate funded by the National Institute for Health Research and is interested in cells and materials for tissue engineering and regenerative medicine.

Friday, 24.03.2014, 1.30-2.30 pm
Carbon nanotubes decorated with metallic nanoclusters: from gas sensing to spintronics

Dr Zeila Zanolli (Peter Grunberg Institut & Institute for Advanced Simulation, Forchungszentrum Julich)

The remarkable electronic and transport properties of carbon nanotubes (CNTs) make them very promising for a wide variety of applications in nanoelectronics and spintronics. In particular CNTs could be used as detection element for gas sensing nanodevices thanks to their high surface-to-volume ratio and to the high sensitivity of their physical properties to external perturbations. However, the response of pristine CNTs to gases is weak due to the intrinsically inert sp2 carbon network that characterizes the sidewalls of CNTs. Hence, the functionalization of the CNT external surface is mandatory to improve both the sensitivity and the selectivity of CNT-based gas sensors. In this talk, various approaches to address this issue using ab initio and Nonequilibrium Green’s Functions techniques will be presented. First, the effect of the controlled introduction of defects and of reactive molecular species on the CNTs sidewalls [1] will be considered. Then, the exploitation of the extraordinary catalytic properties of metal nanoclusters (NC) in designing sensors based on CNT-NC hybrid systems will be illustrated [2-3]. In those devices the functionalized CNTs act as sensing unit and gas detection is achieved by macroscopic measurements of the conductivity of CNT mats. Going further, CNTs decorated with transition metal magnetic NCs will be considered and a novel detection method based on local magnetic moment measurements will be proposed [4]. For small cluster sizes, the strong CNT-NC interaction induces spin-polarization in the CNT. The adsorption of a benzene molecule is found to modify the CNT-NC local magnetization enough to be detected via magnetic-AFM or SQUID magnetometry. The present ab initio simulations predict these CNT-NC hybrid systems to exhibit an extraordinary sensitivity to gas molecules with respect to other conventional methods. In addition, CNTs decorated or filled with metallic magnetic NCs are promising for spin-dependent transport applications since they make efficient spin injection compatible with low-resistance contacts. [1] Z. Zanolli, J.-C. Charlier, Phys. Rev. B 80 (2009) 155447. [2] Z. Zanolli, J.-C. Charlier, ACS Nano 5 (2011) 4592-4599. [3] J.-C. Charlier et al., Nanotech. 20 (2009) 3755011. [4] Z. Zanolli, J.-C. Charlier, ACS Nano 6 (2012) 10786–10791.

Short Bio Zeila Zanolli is Marie Curie IEF at Forschungszentrum Jülich, Germany having received her PhD in Physics at Bari University, Italy. She uses first principles techniques such as Density Functional Theory (DFT) and Non-Equilibrium Green's Functions (NEGF) to investigate the structural, electronic, magnetic and quantum electron transport in nanomaterials. Her interests include carbon nanostructures, 2D materials, III-V semiconductor nanowires, and multiferroic materials.

Friday, 14.03.2014, 1.30-2.30 pm
Engineering nanoscale devices for applications in data storage, multilevel logic and sensing

Dr Harish Bhaskaran (Department of Materials, University of Oxford)

The use of well-known design rules of thumb at the nanoscale to yield simple yet effective devices and structures will be presented. In this particular talk, I'll focus on two aspects - the design of NEMS for ultrasensitive mass sensing as well as the use of phase change materials in photonic devices to create co-located and novel logic and data storage. To present the work we are now developing in my group, I'll also give a very brief outline of some ambitious goals to create pick-and-place assembly tools at the nanoscale.

Short Bio Dr Harish Bhaskaran, Research Lecturer and Leader of the Advanced Nanoscale Engineering Group at Oxford Materials will deliver a talk on Friday 14th March for the Begbroke Science Forum. Harish obtained his MS and PhD from the University of Maryland before moving to IBM Research – Zurich in 2006 and then on to Yale University in 2009. In 2010 he became a Senior Lecturer in Engineering at the University of Exeter before taking up his current position at the University of Oxford in 2013. His research focuses on nanomechanical devices, data storage and nanomanufacturing. A brief summary of the general topic of his talk is presented below.

February 2014

Friday, 21.02.2014, 1.30-2.30 pm
Controlling the electrical properties of polar ABO3 perovskites: are we in control?

Prof Derek Sinclair (Department of Materials Science, University of Sheffield)

Neutrons are a unique probe to find out ‘where atoms are and what atoms do’ in materials. They provide complementary information to X-rays, they are highly penetrating but non-destructive and have the advantage that they see hydrogen and deuterium differently, thus enabling isotopic labelling. Oxfordshire hosts a world-leading neutron facility, ISIS, which is available for scientific research in a broad range of fields. In this seminar, I will run through what ISIS is and how it works, and give you a flavour of the type of answers that one can get from this technique. I will try and cover a wide scientific remit, but will spend a little more time talking about my expertise in soft matter and bio-related examples.

Short Bio Victoria Garcia-Sakai is an instrument scientist for the neutron backscattering spectrometers IRIS and OSIRIS at the ISIS neutron facility. Victoria received her PhD in Chemical Engineering from Imperial College London and moved on to a post-doctoral position at Pennsylvania State University before becoming an instrument scientist at the NIST Center for Neutron Research in MD, USA and then moving to ISIS in 2007. Her research focuses on understanding dynamics in soft matter systems by combining neutron scattering techniques with different time and spatial scales; and molecular dynamical simulations. In particular she is interested in the dynamics of polymeric and biological systems.

January 2014

Friday, 31.01.2014, 1.30-2.30 pm
Neutron techniques for Materials Science at the ISIS facility – particularly in soft matter

Dr Victoria Garcia-Sakai (ISIS neutron facility)

Neutrons are a unique probe to find out ‘where atoms are and what atoms do’ in materials. They provide complementary information to X-rays, they are highly penetrating but non-destructive and have the advantage that they see hydrogen and deuterium differently, thus enabling isotopic labelling. Oxfordshire hosts a world-leading neutron facility, ISIS, which is available for scientific research in a broad range of fields. In this seminar, I will run through what ISIS is and how it works, and give you a flavour of the type of answers that one can get from this technique. I will try and cover a wide scientific remit, but will spend a little more time talking about my expertise in soft matter and bio-related examples.

Short Bio Victoria Garcia-Sakai is an instrument scientist for the neutron backscattering spectrometers IRIS and OSIRIS at the ISIS neutron facility. Victoria received her PhD in Chemical Engineering from Imperial College London and moved on to a post-doctoral position at Pennsylvania State University before becoming an instrument scientist at the NIST Center for Neutron Research in MD, USA and then moving to ISIS in 2007. Her research focuses on understanding dynamics in soft matter systems by combining neutron scattering techniques with different time and spatial scales; and molecular dynamical simulations. In particular she is interested in the dynamics of polymeric and biological systems.

Friday, 10.01.2014, 1.30-2.30 pm
Terahertz spectroscopy of nanomaterials

Dr Michael Johnston (The Oxford Terahertz Photonics Group, University of Oxford)

A fundamental understanding the electrical properties of nanomaterials is critical for the development of new functional materials and for their implementation in devices. Traditional methods of determining key parameters such as mobility, surface recombination velocity, charge-carrier lifetime and donor density are not well suited to many nanomaterials which are often non-planar and difficult to contact electrically. We have used the noncontact method of Optical Pump Terahertz Probe Spectroscopy (OPTPS) to determine these key electrical parameters for a wide range of functional nanomaterials including semiconductor nanowires, graphene, and next generation solar cells. We have shown that InP nanowires have an extremely low surface recombination velocity of 170 cm s−1 [5] highlighting their suitability in photovoltaic applications. In contrast GaAs based nanowires show a high surface recombination velocity but exhibit good mobility (~1000 cm2V−1s−1) and very short (picosecond) charge carrier lifetime, which shows promise for their use in high-speed devices. We have also shown that InAs nanowires can exhibit high mobilities of 6000 cm2V−1s−1 at room temperature. A huge worldwide research effort is currently focusing on the applications of graphene. Chemical Vapour Deposition (CVD) is a scalable method of producing graphene that is very promising for large-scale graphene production. We have shown that the THz photoconductivity of CVD-grown graphene is very sensitive to the adsorption of environmental gasses (O2, N2) and we provide evidence of THz stimulated emission from gas-adsorbed graphene. Our studies of semiconducting MoS2 monolayers show no effect of atmospheric gas adsorption on their THz photoconductivity, but very short photoconductivity lifetimes.

Short Bio Michael Johnston is a Reader in Physics at Oxford's Department of Physics and has been a Fellow of Corpus since 2002. Dr Johnston obtained his PhD in Physics from the University of New South Wales (Sydney, Australia) working on electron behaviour in quantum-confined systems. In 1999 he joined the Cavendish Laboratory at the University of Cambridge, where he was instrumental in setting up a new programme of research on the spectroscopy of semiconductors in the far-infrared ("terahertz") region. On arriving at Oxford in 2002 he established and currently leads a research group specialising in terahertz photonics and spectroscopy. He has made an important contribution towards understanding the emission of terahertz radiation from semiconductors, developed new photonic devices and is an expert on electron dynamics in semiconductor nanostructures. To date he has published over 40 papers in the fields of ultra-fast and infrared optics. Dr Johnston's research is now focused on the electrical properties and nanoscale systems such as nanowires, and molecular semiconductors. He hopes to reveal the fundamental electronic processes that occur in nanoscale media and thereby precipitate the design of better nano-materials and realise new nano-devices. Further details can be found at

September 2013

Thursday, 19.09.2013, 1.30-2.30 pm
Molecular Structure Transformations and the Kinetics of Carbon Nanomaterial Formation

Gyula Eres (Materials Science and Technology Division Oak Ridge National Laboratory, Oak Ridge)

Carbon nanomaterial synthesis is typically performed at extreme temperatures and pressures that occur in plasmas or flames. During their relaxation the highly non-equilibrium reactive carbon species are trapped in a succession of metastable states corresponding to a broad range of products. The distribution of products is an intrinsic property of the carbon transformation reactions that occur by rearrangements of carbon-carbon bonding configurations during self-assembly from energetically unstable species. Consequently, these distributions are governed by kinetic rather than by thermodynamic constraints. This approach is highly effective in the exploratory phase of research because the desired structures can be isolated and purified for further characterization using chemical separation techniques. However, this approach is impractical for mass production of carbon nanomaterials that is needed for applications. The complexity of these processes is well recognized and the obstacles to synthesis of carbon nanomaterials with desired structure are related to the poor understanding of the barriers and the reaction pathways connecting initial molecular structures to final products . Controlling the assembly of carbon at the molecular level is the most promising avenue for unlocking the secrets of carbon nanomaterial synthesis. The focus of this talk is on chemical vapor deposition processes that occur at milder conditions promising greater control over the product distribution in the formation of carbon nanotubes and graphene. For controlling the reaction conditions we use a molecular beam environment to suppress secondary gas phase reactions and restrict the growth to heterogeneous surface reactions of specific molecular precursors on a single collision level such as acetylene. The carbon deposition kinetics is studied in real-time using time-resolved optical reflectivity methods. Growth kinetics data alone are insufficient to determine the exact reaction mechanisms, but they allow identification of a particular reaction class with a characteristic product distribution that is critical for obtaining carbon nanomaterials with desired properties.

Short Bio Gyula Eres is a senior research staff member in the Materials Science and Technology Division of Oak Ridge National Laboratory. He holds a Ph.D. in chemical physics from the University of Illinois at Urbana-Champaign. His current research is focused on understanding the mechanisms and the kinetics of elementary surface processes that control the synthesis and properties of interfaces in epitaxial thin films, superlattices, and nanostructured materials relevant for advanced energy applications. The experimental approach combines energy enhanced and nonequilibrium growth techniques including pulsed laser deposition and supersonic molecular beam epitaxy with in situ time-resolved imaging, diffraction, and spectroscopic techniques such as surface x-ray diffraction, laser based optical diagnostics, mass spectrometry, and reflection high energy electron diffraction.

July 2013

Friday, 02.08.2013, 1.30-2.30 pm
Molecular Doping and Organic p-i-n Solar Cells

Dr Moritz Riede (Clarendon Laboratory, Department of Physics, University of Oxford)

Organic solar cells (OSC) have attracted increasing attention in recent years from science and industry. Although OSC have lower power conversion efficiencies than most of their inorganic counterparts, they can have cost advantages, due to low material consumption, simple processing methods as well as the possibility for flexible and light-weight devices.

One very promising approach for OSC is based on the thermal evaporation of small molecules in vacuum to create an organic stack in the p-i-n concept. Its key is molecular doping and the use of doped wide gap transport layers on both sides of the intrinsic absorber layer [K. Walzer et al., Chem. Rev. 107, 1233 (2007)]. The result is a very versatile platform both for investigation of fundamental processes and device optimisation.

There are various ways, in which OSC can be improved and the development of novel organic semiconductors plays a central role. Already subtle changes to the molecular structure can have significant consequences on the OSC performance and lifetime. Thus, much research is carried out on a better understanding structure-property relationships to eventually will allow a targeted synthesis of improved compounds.

March 2013

Wednesday, 20.03.2013, 1.30-2.30 pm
Publishing in Nature Nanotechnology

Dr Fabio Pulizzi (Chief Editor Nature Nanotechnology)

Fabio joined Nature Nanotechnology in July 2012 after working for six years at Nature Materials first as an Associate Editor and then Senior Editor. He has a first degree in physics from the University of Rome La Sapienza, Italy, and a PhD from the University of Nijmegen, the Netherlands. He also worked as a postdoc at the Universities of Nottingham and Sheffield. His research focused on the properties of semiconductor nanostructures. He is based in London.

February 2013

Monday, 25.02.2013, 1.15-2.15 pm
Strain and chemical engineering of functional oxide thin films

Dr Ausrine Bartasyte (Institute Jean Lamour, CNRS (UMR 7198)-Lorraine University, Nancy, France)

Our research is focused on the deposition of functional oxide (superconductors, dielectrics, piezoelectrics, ferroelectrics, conducting oxides) thin films/ heterostructures by pulsed injection metalorganic chemical vapour deposition (PI MOCVD) – a method providing the digital control of the film deposition. The methods for characterization of phase composition, residual stresses, non-stoichiometry, texture, twin/domain structure by means of Raman spectroscopy were developed. It was shown that strain engineering is a powerful tool for governing the film symmetry, texture, domain structure, phase transitions and thermal expansion. The physical and structural properties of thin films/crystals were tuned by changing their chemical composition. For example, optically isotropic ferroelectric crystals (for thermal sensing) or crystals with reduced temperature coefficient of frequency (for acoustic devices) were obtained by chemical engineering. Moreover, the possibility to change by several times the thermal expansion of thin films by applying biaxial strain opens new avenues for temperature compensated devices.

September 2012

Monday, 03.09.2012, 1.15-2.15 pm
Creation of nanostructures at low temperature via self-assembly and their application to bio-medical studies

Professor Toru Maekawa (Bio-Nano Electronics Research Centre Toyo University, Kawagoe, Saitama, Japan)

The gas-liquid coexistence curves terminate at the critical points, where large molecular clusters are formed and as a result, the physical properties such as the specific heat and compressibility diverge and incident light cannot penetrate the fluid; known as critical opalescence. The critical temperatures are generally low; e.g., 31.0 °C (carbon dioxide), 32.2 °C (ethane), 16.6 °C (xenon) and 289.0 °C (benzene). A variety of nanostructures such as carbon onions, coils and fibres are self-assembled in fluids near their critical points. The secondary structures formed by nanomaterials are also focused on. Finally, the application of the above nanostructures to bio-medical studies such as the detection of diseases, separation of cells and bio-imaging is explained.

June 2012

Monday, 11.06.2012, 1.15-2.15 pm
Nano-engineered materials from carbon: opportunities and challenges

Professor Pulickel M. Ajayan (Mechanical Engineering and Materials Science Department Rice University, Houston, Texas 77005)

The talk will focus on approaches used to engineer nanomaterials for applications. Carbon nanostructures, including carbon nanotubes and graphene, will be used as prime examples to demonstrate opportunities and challenges that exist in nanoscale engineering and nanomaterials development. The last couple of decades have seen fascinating advances in nanotechnology. Several exciting developments in recent years allow us to think about strategies we can follow to develop the next generation of materials using nanoscale engineering. The talk will focus on various aspects of nanomaterials such as synthesis, assembly, nanoscale junctions, hybrid nanostructures, nanocomposites, membranes, functional materials etc. The inherent opportunities and challenges that lie ahead in developing nanomaterials based technologies will be discussed.

March 2012

Friday, 23.03.2012
Carbon nanomaterials for nanoelectronics

Professor Jong Min Kim (Department of Engineering, University of Oxford)

Jong Min Kim, BSc Hong-ik, MSc PhD New Jersey Institute of Technology, Samsung Fellow, Senior Vice President and Director, Frontier Research Lab, Samsung Advanced Institute of Technology, Samsung Electronics, South Korea, has been appointed to the Professorship of Electrical Engineering in the Department of Engineering Science with effect from 5 March 2012.

November 2011

Friday, 18.11.2011
Chemical functionalisation, dispersion and self-assembly of carbon nanomaterials

Dr Christoph G. Salzmann (Department of Chemistry, University College London)
This talk will highlight the challenges associated with the covalent chemical functionalisation of carbon nanotubes, and describe the design of new high-performance dispersing agents for carbon nanotubes as well as the development of new strategies for the controlled self-assembly of carbon nanotubes.

Work on graphene recently resulted in the preparation of a new carbon nanomaterial which we named graphene nanoflakes. The preparation of the nanoflakes will be described as well as their chemical properties and potential usefulness for applications in electrochemistry and gas-storage.

Friday, 11.11.2011
Silk processing and production: tracking the embodied energy

Dr Robin Carter (Department of Zoology, University of Oxford)
Silk fibre and it's cocoon composite are tough and strong biomaterials with interesting structure-property-function relationships which can inform materials design. Life Cycle Analysis is a powerful tool which can track the flow of these material's embodied energy through the production cycle. Identification of energy efficient processes can offer biomemetic inspiration for energy-related challenges in fibre processing. Energetically expensive processes can be identified and solutions sought which could conserve energy.