Revealing the hidden microstructure of materials

I’d like to start by just thanking the organizers for the opportunity to speak to you today and it’s very nice to to travel from one national laboratory to another one it’s only 60 70 miles away to the Rutherford lab unfortunately seems to take about two out on the train they don’t quite understand but nonetheless we’re very close and I think we’re very close also in some of our scientific endeavors and and I hope there’s a result of the talk today that it may stimulate some discussion about where we might bring our combined strengths together so if you’ve not visited the Rutherford site this is what it looks like probably yeah it’s quite a clear day today so it probably looks something similar to this a little bit of frost maybe and one thing you’ll notice is that we have our neutron source here which is Isis and co-located with that is a third-generation x-ray synchrotron source diamond that I’m sure many of you will have used so the site is not unique in co-hosting a neutron and an x-ray source where is unique is actually we’re the only source in the world that runs two neutron source is simultaneously I I think it’s always surprising that you take scientist is very creative people and then you ask them to name things and so this is called ts1 and this is called ts2 not particularly imaginative so what I’d like to do today in the short time available to me is to to give you a brief introduction to the neutron technique I apologize if your expert in the technique and I will try and show you that neutron scattering is able to access a very wide range of length and energy scales which are relevant to both curiosity driven and applied research and actually ultimately what we’re trying to do is to take this atomic and molecular information both of the static and dynamic structures and then related to their functional properties because if we can do that we have a complete understanding of the materials and we can then optimize their functional properties so I just give you a brief introduction as to how we produce our neutrons just in case that’s of interest to you and then I’ll give you some examples of the kind of research that we do at Isis and I and I picked out some areas here there are many more this was just a sort of sort of sample and I’ll finish with some some comments on on on the possibilities for moving the science forward using Neutron techniques I’ve taken this graphic here of a needle in a haystack because quite often a lot of the signs we’re doing now is to look for very small effects often dwarfed by far bigger effects and so complexity and very weak effects are a common feature of some of the science the wielder that we’ll talk about so if you’ve not had visited rutherford appleton the neutron source itself attract something like 1,200 use per year from the UK academic communities European and more overseas academic communities but also increasingly a lot of industrial interest either from the sort of simplest form if you like which would be say a case studentship or providing some kind of material and right through to proprietary research where they need the results immediately and they want that there is also a confidential so out of these running 700 different experiments we’re actually any given day we’re running something like 27 different experiments we have 27 instruments 27 different experiments and that generates about about 500 publications per year so it’s a pretty good success rate for a proposal at Isis turning into a publication and actually if you went back to the sort of foundation stones of neutron scattering and actually in 1996 cliff shawn and bra cows were awarded a nobel prize for physics when you turn scattering it was primarily a physics technique if you want to understand the structure of material excitations of material it was broadly in the area of physics but now what we’re saying we’ll see later on today with some examples this has now spread out into a huge range of topics from chemistry fold quite naturally material science but through to things such as Earth and Planetary Sciences engineering applications that will touch upon a farmer biomolecular science and even some examples of of cultural heritage and we’ll just touch on that so I’m sure it’s not needed for this audience but i think it’s it’s useful just to show the area that we that we’re going to concentrate on and of course there’s a rather nice quote from Daniel Carmen who’s a psychologist but I think you won the nobel prize in 2002 for economics actually so quite a versatile character and he said that human beings cannot comprehend very large of very small numbers and it would be useful for us to acknowledge the fact now of course we can as scientists hopefully can try and understand these largest small numbers and of course we can’t think of anything pretty much bigger than the galaxy and we probably can’t think of anything which smaller than the Planck length but actually what I want to show to you today is that in

this region here this is where in this is essentially the world in which we live in and the materials that we rely on a racially driven by the lens scales from the angstrom up to the meter if you like and so what I should like to do is to give you some examples of why this lens scale is important whether we want to know the atomic structure of a new high TC material or for example we have DNA helix here whether the diameter here is is save order a couple of a couple of nanometers and I just put up this little photograph that I took in the lab relating to the discovery of the Higgs boson just because I thought it was rather nice that there was a lot of high-profile publicity on the TV and the radio and so on about to discover the Higgs boson but actually if you just wander around the lab you see somebody’s written a poster about it and I think that’s a really really encouraging sign of an active and active laboratory okay so why do I think this lens scale is relevant so I’ve just taken our small subset of here from the angstrom through to the micron and actually if we think about the kind of material problems that we might want to challenge at the angstrom level if a new material comes along they’d be safe let’s say it’s high TC or say MGB to new super condos comes along we want another atomic structure we want to know with atomic resolution so we need to have a probe that actually covers the angstrom level atomic scale and also intro Tomic length scales if you go a factor 10 obvious here into the realm of nanoscience and you start to talk about things like surfactants for example or you start talk about thin film materials and this is for example what you might find inside the readhead of this laptop here very much bigger you going to lend scale of proteins and viruses through to the micron scale which is I guess is not so so attractive at the moment as a length scale this is with the push towards nanoscience but actually microns as the feature size of a lot of devices that we rely on so for example if you’re interested in plastic electronics that a lot of the feature sizes that you’re going to be thinking about a present layer on them might on lenska and so neutron scattering is going to cover all of the length scales it’ll actually go much further and we’ll talk about things where we can image materials on the millimeter lens scale for example but this is where the vast majority of the research actually lies and of course we live in a material world and if you want to understand the behavior of graphene or you want to understand a new hydrogen storage material you need atomic resolution data if you want to understand more complex things such as proteins for example again you need to have atomic resolution data but you also probably want low resolutions data as well because you want to understand the behavior this material in realistic environments so in solution for example you might want to understand superconducting materials and there’s little movie there which of course as these things always do has failed start no maybe and we want to understand phase transition so we want to understand how materials behave when they go through a phase transition whether that’s on the atomic land scale or increasingly we want to take advantage of self-assembly so rather than having to do the assembly or the construction ourselves through complex expensive slow lithographic techniques perhaps we can do it let nature of the work for us in this case of a phase separation in some polymeric systems and quite often the materials that we want to study are going to be magnetic hopefully there we go so we want to understand my native materials and we also want to understand complex systems so if you want to develop a new safe drug delivery system then you want to be able to access these complex structures but with atomic or nano scale at least our resolution and so what I’d like to convince you in the next 35 40 minutes or so is that neutron scattering allows us to access all of these phenomena okay so I apologize it is all very familiar to you but there’s sort of six points that I wanted to to pull out about the proper the neutron that make them so interesting so unique the first is that the energies of thermal neutrons are comparable to the excitations that you exist that existing materials so if you take a typical neutral energy which is a border a few millivolts that corresponds to a temperature about 300 Kelvin and so we expect that neutron scattering is going to be able to tell us about molecular vibrations phonon excitations that has spin ons and so on equally through the de Broglie relationship from the energy we have the wavelength and we find the wavelength is of the order of angstrom ok so we expect to see diffraction we expect to be able to obtain structural information from the angstrom up to the micron land scale with with very impressive resolution they enter up to the nuclei of the

strong force and so actually this is a big contrast to x-rays of course as you know x-ray scattering the electron cloud so it goes as said the scattering whereas neutrons it sort of varies randomly across the periodic table which means we can see very light atoms in the presence of heavy ones so if you’re interested in the hydrogen economy they’re neutral skechers gonna be a powerful tending to local localized hydrogen when they’re open in which heavier elements and we can also exploit the isotopic substitution so if we change for example hydrogen deuterium they have very different scattering lengths which means we can tailor our experiments to actually get the information that we want and I’ll show you example I have that of course neutrons are neutral particles which makes them highly penetrating so we can go through lots of material for x-rays you tend to have to go to very high energy x-rays with one hundred kilovolts and beyond to get penetration into materials but actually I neutrons are relatively straightforward and again we’ll see some examples of that and then non-destructive and this fact that they’re penetrating means that you can easily get through complex sample environment so if you want to go to extremes of temperature pressure pH magnetic field electric field hazardous environments a neutral scattering is probably going to be able to help you in that respect they also have a magnetic moment sir as it’ll spin dipole which means we can couple to the magnetic induction in a sample to study the molecular structure and the magnetic excitations they have a spin so we can polarize them and we can actually use that spin information in a very efficient way but we shall see so having talked about length scales I just switch briefly to discuss the energy scales and on the slide I sort of have momentum transfer against the energy scale along here or the time scale here and you can see the kind of things that you can access through a whole range of techniques whether at the inelastic x-ray scattering Brillouin scattering X pcs type measurements ramen for example and what you find is that neutron scattering covers a big swage of this this energy scale landscape which takes you from very low energy excitations to look at things like to be able to look at magnetic excitations structural excitation so we talked about but through two tunneling rotation and molecules diffusion of systems are going to study hydrogen diffusion for example in a backing material lithium and then neutral sketch is going to be interesting over this entire length scale energy scale sorry so we have a probe that allows us to access the relevant length scales from angstrom through two micron and Beyond and the energy scales just take us from the coherent excitations of the system right through to the motions of molecules for example so just briefly how do we produce our neutrons well the several ways you can do it one is to is through fission and so this was discovered in 238 by lise meitner Otto Hahn where they irradiated some uranium with neutrons and this is a the aisle reaction in the South of France that some of you may be familiar with a 58 megawatt reactor and the process here is one takes a heavy target nucleus uranium at bombard you and neutrons and the fission products you find that some of the matters missing one percent which is given off as energy and of course that’s why you use it air to generate electricity but in our case what we want to do is to optimize the production of neutrons not the production of heat and so what you do is you have a small core which you keep cooled by d2l so that’s 58 megawatts at the I ll and so you could say well can you go beyond that and in fact the Americans thought about doing that they had a proposal for a new neutron source at Oak Ridge and you can probably tell from the drawing that it’s reasonably old they had a proposal for a 330 megawatt source but it was quite rapidly realized that that was just not feasible from materials point of view for example the engineering required to build such a machine was was well rather well the challenging shall we say so the other alternative which is what we pursue at Isis is actually the so-called spallation process where one takes target nucleus tungsten for example and bombard it with high-energy protons in our case 800 mega electron volts the proton is absorbed by the target nucleus it gets excited starts to boil off and it kicks out a whole load of particles including neutrons which can then go on to be using their experiments these neutrons are very high energy their mega electron volts we actually want milli electron volts so we slowed them down through the process known of moderation but actually it’s a very efficient process we generate something like 60 neutrons for every collision and it doesn’t generate a particular high amount of heat so this is a very scalable technology so I said that the il was a 58 megawatt source the second target station of Isis is only a 48 kilowatt source ok so this is a very scalable technology and indeed if you go

to oakridge in the states where they are proposing to build the high power reactor source then have a very nice relation neutron source based on this technology which is megawatt level okay so what I just show you is briefly how this all works and so we start off by producing H minus ions which we accelerate up in a radiofrequency quadrupole up to something like 665 ke V so a few percent of the speed of light we take these H minus ions and then put them into a linic where we accelerate them look 270 mega electron volts smooth like thirty-seven percent of the speed of light we then strip off these extra electrons with a thin aluminum oxide couple microns thick aluminum oxide film which remove the electrons and we inject our proton beam into the synchrotron accelerator they go round for about 130 turns where they get bunched up into two groups they then start to accelerate making about something like 10,000 turns and then 50 times a second they’re kicked out from the synchrotron ring down to one of the target stations on their way down there there’s a little bit of focus in a little bit of steering of the beam and then ultimately they they smash into the target on target station one is a tungsten target but so big which then produces the neutrons so hopefully you can see here you see the two bunches of protons being accelerated up and then 50 times a second they’re kicked out to the target station now I said that we run to target stations so actually what we do we take every at one pulse in five we send off to our second target station okay so one target station ones are 50 Hertz one runs of ten minutes now so here you can see the proton beam being kicked out it said send down to the target station hit the target and produce the neutrons so the nice thing in this in this measurement is that we know exactly when the neutrons have been produced we know when we detect them because obviously we know the distance between the neutron source and our instruments and so by knowing the so-called time of flight we can then work out what the energy of the neutrons are so the characteristic of many of these instruments is that rather than having a single wavelength of neutrons we had to have a polychromatic beam so unlike say a a conventional love x-ray source where you may just have a copic alpha line here we have a broad spectrum Neutron wavelengths in the single measurement which may means the very nice techniques for surveying large areas of energy and momentum space okay so let’s let’s start to talk about some of the signs that walking can start to tackle when you have such capability and it’s rather nice to be able to connect the research that’s performed at Isis with with a lot of the global challenges and I just sort of thought I would take some examples out of the ISIS portfolio just to illustrate some of the research that we do and I know some of it will resonate to the work here at at MPL I’d also make the the important point of the need to have a strong curiosity-driven research program as well in the sense that curiosity-driven research really there’s no distinction between that and applied research it’s quite often just the time scale which is relevant so we would hope to the materials that have been studied under this sort of heading actually are the applications of the future put on there on the longer time scale okay so let’s let’s take the first one let’s take care energy and just to give you a feel for the diversity we talk about energy and then the neutron scattering program and Isis we’re not just talking about a single experiment we’re actually taking a huge range of experiments looking right down from the macromolecular length scale through things like photovoltaics the operation of fuel cells and sits you the performance of lithium batteries for example right up to this is this is part of the heat exchanger at dungeness be one of the nuclear reactors where neutron scattering was used to actually to certify the quality of some of these these wells as well obviously are in a very hostile environment here they go through a complex a welding and post and kneeling treatment and actually by using neutron scattering to understand the quality particular strain in these welds it was part of the case that was allowed the reactors to be realized by another five years so going from this atomic understanding right up to the understanding of welds and there’s a whole range of techniques that one wants to use now I’m not going to focus on the techniques themselves too much today I be happy to talk about them later on but there’s a huge panoply of techniques that we can bring to play on these systems and equally you see the quite often there’s a nice complementarity between using a neutron technique and the x-ray technique so let’s let’s just take some of these examples then so if you want to have a mixed energy economy then these are the

kind of things that you you probably want to attack Lee and actually I think it’s fair to say that we could give examples of neutron research that sort of fits into all of these areas but I’ll only concentrate on on a couple namely hydrogen and also and also solar so let’s um let’s start with with with hydrogen so if you want to produce a an efficient hydrogen store then has to have some capabilities you need to be able to store a large amount of hydrogen ideally wants to be recyclable you wanted to offer as in terms of being able to store the hydrogen take it out reloaded take it out and you wanted to operate at a at a sensible a convenient temperature so this is work between researchers at Isis and Toyota trying to understand the behavior of one of their hydrogen storage materials when there was a belief that actually this material was not storing as much hydrogen as was possible even so it was able to power a Toyota handle Highlander the than the 30 and 50 miles between Tokyo and a sacker on a single charge so what does neutron scattering have to bring to this well it’s a very nice example of how we use in situ techniques to add value and information to the neutron scattering measurements so this is a capability that was developed to provide a gravimetric analysis which is as shown here and we do this in situ on the beam line and actually what was discovered in these materials and this is not so clear is that actually using neutron diffraction you can actually locate precisely where the hydrogen atoms on that’s very difficult to do with any other technique especially when they’re in the presence of much heavier atoms and what we found from this research is actually that there are some diffusion channels through which the hydrogen moves and they actually get blocked in the stroke and you can sort of get a hint of this from these beautiful T a ninja’s but it’s actually when you combine the tem images which is a rather localized view with the neutron scattering view it’s a much longer a statistical view of the system that you can start to understand the behavior of these materials because we have this broad wavelength range that I talked about it also means that we can study the kinetics of the loading for example so normally if you had if you just have thermal gravimetric analysis this is the kind of thing that you be able to do you be able to as a function of time you’ll be able to work out what was going on in the sample but at the macroscopic level you want to have the atomic understanding and so this is an example of looking at the conversion from lithium 3 nitrogen to the material that’s hydride adore in this case we use deuterium and what you see here apologies for the yellow labels here this is a function of time this is the D space and the sample and you can see as you load up the sample how various Bragg Peaks are arriving and disappearing and you can actually track the transition of the material from living the 390 up night try to the head the deuterated air material in real time so you have the book thermogravimetric analysis data and you combine that with the atomic resolution Neutron beta so let’s um let’s just switch now to the solar aspect and this is a rather nice figure from from david mckay at Oxford which shows something like 600 x 600 square kilometer a ello shaded region here which is actually if you would convert that alter photovoltaics thou produce enough energy for some like 500 million people per year of course the realization that enough energy falls on the planet every day to provide our energy needs for a year tells us that if we could only get better at converting photons to energy we’d have we really be able to tackle some rather large issues in society in a little red square represents what you’d need for the UK so you can tell it’s important his Barack Obama at an Air Force Base in the States I suspected it up there today he’s prob about more important things on his mind but obviously at one point photovoltaics were important to him and actually there’s various ways you can provide energy from photons and one way is to use semiconductors which I’m sure we’re all very familiar with where we take doping and material to create an electric field and depletion region which allows us to create electron hole pairs that we can then split and form a current so these are very efficient but they have some disadvantages there tend to be rather expensive they’re heavy they’re flexible difficult to process and so on but they’re very efficient so the question is can you do something far simpler and one possibility is to use organics so this is a where you take a single organic layer and you provide it between two materials which have different work functions and so you create an electric field across them so a photon comes in is absorbed you excite an electron from the highest occupied molecular orbital into the lowest unoccupied orbital and then you create an electron hole exit on which you then need to separate and actually in a simple structure like this that’s not a particular efficient process so what you

need to do to optimize the structure is well first of all you want to absorb as many photons as you can so you probably want to have reflections in here too to make sure to give you the biggest chance of absorbing the photon you want to then efficiently create the exit on efficiently break it up and have good conduction to give you your your device and so what you can do is to add different layers so rather than having a single layer you want to have a donor or an acceptor so this interface here is going to be crucial and understand the efficiency of those devices at all perhaps you want something that’s actually heterogeneous that consists of lots of different interfaces best chance of creating that exit on and then and then tearing it apart so you want optimize the absorption the reflection the recombination and the conduction so so this is a rather nice figure although it’s pretty much out of date now which shows you the efficiency of various cell structures as a function of the year and so you see here at the forty percent level you have these royal beautiful semiconductor devices okay so this is where the efficiency is actually if you look down here you see there’s a whole range of devices which have relatively low efficiencies and in fact the consumption of semiconductor photovoltaics is sort of as increased exponentially over the last the last couple of years but actually rather than having these these heavy but efficient structures perhaps there’s a need to have rather simple structures but light but have a lower efficiency maybe make bigger coverage put them into unusual applications and but the efficiency is rather low actually I say this is out of date because now you can buy I think from companies like Samsung you can buy organic photovoltaics with in commercial applications with a sort of ten percent efficiency rating so how can we learn more about these structures actually sorry I just meant to say that one of the reasons for concentrating on these rather low efficiency devices is you have nice attributes that you can just print them on to things so certainly for lots of novel applications or applications in the developing countries countries this kind of technology is going to be interesting so typically if you want to look at these PVS kind of techniques you might want to use obviously you can measure the the optical efficiency or you might take an AFM image of the surface and you sort of see this is two different samples are two different processes and you see the surface looks different but it does only tell you a great deal but what’s going on the system so neutron scattering we can take a non-destructive measurement and data this is q look something like this be happy to talk about the data of people are interested but obviously what you don’t want to do is to go from just raw data like this you actually want to understand what is the structure of this material how does it look away from the surface and so one of the challenges we have in Isis is firstly to take data like this but then to make a child’s play to go from here some children playing with data at secure from the data actually through to essentially a cross section of the material so this is a view away from the surface of the structure the surfaces here and essentially you’re drilling down through the sample and each of these layers is actually shown up in what we call the scattering intensity okay so that the length scale here is angstrom so you can see you have angstrom resolution and you can see justice if we the technique so this is that these two sisters have been annealed and actually what you find is that in this annealing process the interface between the electron exception electron donor is actually far sharper in this case and also the scattering that density has been boosted up so the annealing process has changed the structure of the material and actually changed its efficiency and so this is actually one half of a structure that looks something like this so we haven’t got the I two electrode on the top but here’s one of the electrodes and here are the two different materials this is electron acceptor this is the electron donor and all that’s done non-destructively so this is a real a real opportunity so this is you have tunable molecular engineering you have high absorption coefficients it’s a real challenge though because the sort of cooked some competing led scale so the typical diffusion length scale of these exit owns is typically tens of nanometers to get the best absorption material you’ve probably 200 nanometers of material so it’s a real lamb it’s a real balance so we need to have novel structures to really boost up this efficiency and maybe start to deal with some of the degradation that’s seen in some of these polymeric devices but clearly there’s a lot of scope for improvement there okay so let’s just talk very briefly about some of the engineering applications and so this is a this is some work from Phil withers at Manchester and rolls-royce and so for them in a jet engine the thing that is limiting the performance of the jet engine is the station material science ok so the the

officially engine is is driven by the pressure and the temperature and the central core of this engine and so to improve these characteristics and improve the durability there’s various things that you can do you can play around with the properties of the material so you might want to develop new alloys for example you want to minimize the residual stress in those materials as a result of the fabrication process and you want to understand the applied stress that actually takes place when the engine is an operation okay so you can sort of start playing around with these to try and optimize their performance so this is this is an example of a welding scheme that rolls-royce wants to use is so called inertial welding where you essentially rotate at high speed one of the objects that you want to well together the other one of stationary and you just spin them up and then you stop spinning them and so you stop driving the spinning you just push them together it generates a huge amount of fees and welds of materials there’s a very efficient at welding method but actually for this particular application rolls-royce had developed two new and nickel-based superalloys and conventional techniques were not able to to weld materials to the to the standard that was required so so this is part of the welding ring that they brought to Isis it’s physically it was a peep about so big and what we can do is using neutral techniques we can actually map out the stress within that welded region okay so the length scale here is quite like this is something like a five by five millimeter section of the the of the strain field within this material I think it’s not a section as in we took up a sexual material it’s actually from this this piece of kit and what you find in the eyes welled in case that you get these regions of extreme extremely high strain for the characteristic heat treatment that was normally performed you can see that it reduces the strain in the material but it’s still an unacceptable level but actually with the sorry with a modified treatment post weld heat treatment you can see that we can get the strain down from 1500 megapascals down to 400 which is which is exactly what rolls-royce we’re looking for so we’ve gone from angstrom resolution data up to millimeter resolution data with the same probe and actually I just put this sliding just for fun because it’s son of this is looking at magnesium alloy but again it gives you an example of the kind of size of samples that we can actually deal with so from a few nanometers of material to quite a few kilograms of material one of the new things that we’re we’re pursuing that Isis is is to understand the behavior electronic circuitry when it’s irradiated with high-energy neutrons so I said that we spend a lot of time trying to produce a milli electron volt neutrons because of all the useful characteristics actually if you go up into the upper atmosphere there’s a large density of mega electron volt and neutrons and there’s concern that these neutrons can cause failure in electronic circuits so they can actually corrupt data so flip a bit of data or they can actually cause physical damage in the device and so actually looking into the ISIS Neutron target what you find is a spectrum of neutrons that matches very closely to that of the upper atmosphere so actually one hour in the neutron beam and Isis is equivalent to 100 years flying at 30,000 feet and so this has been learnt and we’re currently building at the moment which is to provide test facilities for chip manufacturers so they can certify their electronic circuits against these high-energy neutrons and of course as feature sizes get smaller and smaller the probability of these events becomes bigger and bigger and just I show this clothing it’s just so impressive if you think this is the entire road map I think the feature size in this laptop is probably thirty two nanometers or something like this and I think they’re already rolling out 14 nanometer type integrated circuits so that is just just phenomenal and as the feature size gets smaller the risk of an interaction with the neutron becomes bigger and so we need to understand how that works okay i mentioned cultural heritage let me give you let me give you an example this is using neutron scattering to actually to actually produce three-dimensional tomographic images of material so this is the Australian nobleman to the Renaissance bronze piece came from the Rijksmuseum in Amsterdam and by just simply taking images of this material in the neutral ambience we rotate around which in the same ways you can do with x-rays we can build up a three-dimensional structure of the of the artifact that we’re

studying at sea because it’s neutral scattering we can do far more than that we can tell you about different materials that are contained in that in structure as you can sort of see here if we can make cross section and then we can identify regions where there seems to be excess material sort of around the knee region in this particular case but we can go beyond that what we can actually do is to take this tomographic data and to go in and then use diffraction to give us a Tomic resolution data so the imaging data is in real space obviously and it’s submillimeter resolution but actually you can then go in and get atomic resolution because you know where everything is now because you’ve done the tomography and so we can see here if we look inside the piece we can find as cast bronze so we can make because it’s diffraction we can make an elemental analysis of the material inside the structure which is shown here and then you can actually see inside there are some repair bars that have been added at a later date and you see the structure is very much different rather mean as cast bronze it looks like unalloyed copper so you can see how the artifact in this case have been there I’ve been repaired okay let’s just give a couple very brief examples about health care type applications and one of the things that we can do is that neutrons are very flexible at looking at different sorts of interfaces so if you want to look at the interface between the soil in the solid that’s fine solid and liquid that’s fine liquid and liquid that’s fine air solid and liquid and so on so this is an example of trying to understand the role of a particular protein that is found to be deficient in premature babies and the role of this protein is to lower the surface tension so that it makes the Long’s more efficient breathing oxygen okay and so the idea is can we understand how this particular protein works and of course because there’s a biologist far more complex than that there’s a whole load of lipids floating around in the system as well so what we can do is to try and make a model of this of this long which in our case just consists of a water and air and we can add the protein and we can also add some lipids but then what we can do is to actually mimic the effect of breathing by compressing and expanding these layers and so when we inhale at a low surface tension five mil millon Newton’s per meter we can then use our user on technique to actually understand the ordering of the protein and the molecules at the surface okay so you can see if the black curve is dominated by the protein you see that it sort of sits near to the surface and you can tell where the phospholipids are there are the location of density which tells you they’re quite highly disordered but then as you start to exhale what you find is that the the lipid bilayer forms at the surface here and becomes ordered and the protein is driven down into the liquid into the water in this case so actually by understanding the behavior but only of the protein but also it’s this the lipids that go along with it you then stand a chance of being able to create synthetic versions of what occurs naturally in nature so in a similar vein this is work with the University of Reading looking at planned events proteins so here’s a membrane of in this case we’re trying to understand the behavior of wheat and what you find is that the binding cipher parinda lame which is shown here actually dictates whether the wheat has a soft or a hard texture which is very important commercially because that means where you can sell your product whether it’s through something of high value such as wheat for making bread for example with a nice soft flour texture or for less profitable up for the harder texture and actually it turns out what drives that transition is is driven by the binding of pure under limb and so actually we’re neutron scattering we can actually say with with an sub nanometer resolution we can actually say where the probe the binding sites are in that material and you can then again this is biology so that’s complexity so we can add a little small molecule this is an antifungal antibacterial molecule and again we can understand how that inserts itself within the membrane layer so that picture that I told you just was essentially a one dimensional view away from a surface if you want to go beyond that we can actually tell you about the full three-dimensional Lord room and so this is an example I have a particular material f127 subhanak we need to worry about that too much but the idea is can we understand this behavior at the surface and we’re going to provide produced two surfaces one is hydrophobic and one is hydrophilic and because of the capability of the neutron technique we’re going to be able to do that in a depth dependent manner okay so here’s some data taken at the critical

wavelength which means we have a lot of neutrons are scattered from the near surface region and we have the hydrophobic interface and hydrophilic and what your scene is the organization of that polymer onto that surface okay so straight away if you look at the critical wavelength for the two different surfaces what you see there’s some sort of broad ring of rolla diffuse scattering which is telling you’ve got a micellar ordering with a distance between the micelles of about 160 angstrom when you go above the percolation limit and this is of interest or a lot of polymer processing industry what we find is that you start to see ordering near to the surface okay and you find it’s very different so there’s some elements of hexagonal close-packed here for the hydrophobic surface whereas you have something looks more cubic as the hydrophilic interface so okay that’s rather nice you can see different ordering near to the surface but actually if you go below the critical wavelength so this was at the critical wavelength so now we’re more both sensitive okay so Roger stood in the surface we’re still in the book and what you find is a hydrophobic you well you still they sort of look reasonably similar I guess that you have this my cellar or drink but that the structures now are looking more similar so in the book the effect of the interface is obviously less important because you’re further away and so these things start to look rather similar whereas if you look just in the surface region by going above the critical wavelength you see that they’re very different so you see you have my cell ordering at the very top of the structure which you don’t have in the hydrophilic system so you’ve got an in-plane ordering so you know where is cubic or X agonal close-packed but you also know how that’s distributed in the third dimension and you can study these things as a function of time this is certainly transition from my cell at a physical formation and this is quite old data now some like this is taking data on the 15 seconds put rashly starting to get time resolution of order of a few hundred milliseconds so we can step in the right kind of case we can study these transitions from the sort of lense cap okay let’s um let’s talk about some of the work now in advanced functional materials and so here’s a rather nice example of multiferroic studies so obviously water frogs and materials with with more than 140 a property as I say fair electricity and ferromagnetism and this is a recent recent prl from Roger Johnson and Oxford so a lot of the multi 40 cinnamon studies so far have a cycloidal my nephew structure okay and that’s like loyola structure comes from the interactions between nearest neighbor and next nearest neighbor and interactions lattice for the spin-orbit interaction and so you have diligently mariah interactions and that explains a large class of the multi fair oaks that that have been thrown at the moment but using neutron scattering we can study not only the atomic structure but i’m a native structure and so you can really start add value to the sort of measurements you might make in in your in your home lab so in this case specific heat susceptibility or the electric polarization and actually provide this full description of the atomic a magnetic structure and indeed in this particular class of multiferroic it’s believed this description of the cycloidal magnetism is not valid for this particular class class of system if you want to study a prof skies for example this is a possible alternative to pzt you can see here the sort of sorry this hasn’t come through this this is sort of showing you the distribution of bismuth titanium iron and magnesium at the various stomach sites and the sort of length scale here is the sort of point 1 angstrom with the resolution with which we can identify the location of these particular items now actually an increasing a trend in the size of performed is the coupling of the experiment experimental data with with computational modeling and so this is a rather nice example of a calcium compound which here’s the data which you can see here and this is a 30 of the diffuse catalyst with a short-range ordering in this calcium system so you can see the data at the top and actually hear some DFT calculations so you really have a full description of the material and this is actually something that Matthias copeman has been working on using gpus to very efficiently calculate the DFT and then relate that to the scattering the usual experiment so you have a very nice understanding of the short-range ordering in materials i mentioned that neutrons a very good at parametric studies we saw the case of hydrogen be loaded into olivium compound this is an example of studying the miletti structure of this material calcium iron for arsenic 3 so this is an analog of the predicted superconductors this material is not super conducting but you see that has a rather complex magnetic ordering and so you can just

with temperature rather than just fall in a single Bragg peak we can actually study a huge range of reciprocal space on the same measurement so you have a complete understanding of the atomic structure but also you start see that the magnetic structure as it appears at different temperatures and you can see how the intensity and the the origin wave vector changes with a function of temperature in a very very efficient manner so that’s talking about book systems actually you can apply a lot of these techniques to to thin film systems and just some very recent example is actually this is an antiferromagnetic semiconductor and this is a thin film sample it’s not particularly thin at children animators actually have data from films as thin as 70 nanometers first time we’ve tried these measurements but we can actually solve the miletic structure in thin-film systems so whereas previously we had to rely on both single crystals were reasonably small sort of fractions of a cubic millimeter as do diffraction with the new capabilities we have now we’re able to do that from epitaxial thin films so we can solve not only the chemical structure we sort had a rough idea that was from the x-ray data but actually we could solve the bonetti structure from just a few tens of nanometers of material okay I’m going to skip these two slides and just talk for the last few moments about superconductivity I think it’s a nice example where new capabilities lead to new science so we’ve just gone through a hundred years celebrating the discovery of superconductivity and of course the thing that enabled that discovery apart from this gentleman’s genius was the fact that you could liquefy helium so you get to low temperatures that allowed you to see this remarkable transition in mercury and here we sort of come full circle with the discovery of the Higgs boson at the beginning of the talk because of course one of the things that powers the CERN is superconducting cables so this is a previously with copper what you need to deliver 12 and a half thousand amps and this is what you need to a superconducting cable and so so we can claim that we have a role to play in the discovery of the Higgs boson but of course there’s a whole range of other applications from civil inducting Magnus through any more scanners and so on and this it must be kind of mainstream now because it’s actually a little YouTube video which is a dance about superconductivity but I’m not going to I’m not going to go there unless somebody wants to really see it okay so I this is not so clear and this just sort of shows you the transition temperature is a function of year and it really just shows you that the curiosity-driven research and the fact that materials can just come from left field means that we can never be fully oh sure that we understand exactly what’s going on these systems so here we have mercury in 1911 and then you see that you discover the new panicked I’d superconductors which is somewhere up here here’s these plutonium 115 compounds different display superconductivity and of course all the the high TC materials and so on so neutron scattering has a really important role to play here in superconducting systems or more widely in strongly correlated systems in the sense that these that they’ll understand the electrons in these systems is one of the major challenges contemporary solid state physics and actually being able to understand the excitations in these systems is absolutely vital because if you understand the excitations in the system you so you have access to the dynamic susceptibility you actually pretty much understand everything at the atomic level about what’s going on the system so you can produce a very rigorous and robust test of theory because if you understand how the atoms all the quasiparticles are moving around then you obviously understand what forces they’re experiencing so you have a complete description of the material and so neutron scattering gives you that here’s some rather beautiful data it’s rather all know but it’s still beautiful from steve haden and jontron croire looking at the excitations in a range of cooperate superconducting systems in which case that the sort of glue that binds the pairs together is not not photons but but it’s actually it’s bleed to american origin and what this Neutron data show is to sort of seen the same kind of symmetry in two different systems sort of tell you about the universality of the data so this is this is in book material if you want to go and look at thin film systems we’re sorry you need to obviously again you need to have the software to make this data readily accessible oops if you want to look at thin film systems then you can do that again when you obviously there’s a huge range of applications of using interfacial phenomena to understand the materials and so i’ll just give an example

relating to superconductivity so this is the case of taking a simple superconductor in our case led it’s actually type 2 in this case is kind of dirty LED and what we can actually see is we can start to visualize the vortex structure within a single layer and so what we’ve done is to take a relatively thick film of lead in this case almost 200 nanometers thick is probably on the limit of the sort of thickest films that we could study and what you see here is some neutron data and the curve through it are actually they’re not they’re not a fit but actually a model so you you take what you know about the material from the macroscopic behavior TC and so on and put it into a time-dependent Ginsburg Landau theory and actually this is what comes out of it and what you find is that you can study as a function of the film thickness and apply magnetic field you can study the structure of the vortex lattice within that material so in this case the thinner films we can only ever support a single layer of vortices but actually make the film thicker you actually can self-assemble a bilayer vortex structures you can go beyond that you can actually look at the flux line lattice within thin films and actually again new capabilities deliver a new size apologies for the blue font here this is a 717 Tesla magnet that it’s part of an eps RC grant 02 Ted fog and a black bow that burger sorry which you can just put all neutrals captions instruments so if you want to go to 17 Tesla this is the kind of thing that you can do actually again new capabilities leading to new science this is a quantum which has a quantum phase transition and this is sterling the excitation so you see the dispersion relationship in this cobalt material traditionally you would set up your instrument with a single instant energy and you would measure this regional reciprocal space so coming back to that point that you’re surveying a large amount of energy space in reciprocal space and what you see here is the excitation the dispersion of the system you can see a gap here in the zone boundary you can just about see some some high energy excitations about three million volts and you might be able to convince yourself as a gap of the zone center here so normally then you’d have to go away reconfigure instrument I’m re measure again to actually focus on this area at you were the instrumentation developed an Isis now we get that all in the same measurement okay so we can actually in the computer afterwards we can actually extract four different incident energies so if we go from an instant energy of ten down to four million volts you can quite clearly see the gap in the zone sensor if you want to go even further really high-resolution study a really detailed test of theory go to 2 millivolts on the computer and you see very nice to resolve this gap of the zone Center that’s all within the same measurement it’s a really efficient way of making data so I’m almost at an end I think one of the things that we’re driving to do with in Isis and SD FC is to is to sort of put ourselves on this this virtuous circle where we want to be involved in that the smart engineering materials so we want to deliver optimized experimental capability which can then move through to provide optimized a functional properties so if you produce nice material you have detailed atomic and nanoscale characterization backed up almost certainly by computational modeling you then feed that back into produce even more optimized material and this is where we see the role of Isis in this providing this detailed characterization and probably within stfc increasingly being able to provide a high-performance computing resource to close this virtual server so we’re delivering a new instrumentation to try and tackle some of these challenges but I’ll just conclude by hopefully show you the neutron probe can access a range of curiosity driven and technologically relevant research that we can solve chemical amenity structures encounter a short range or disordered systems we can observe the excitations and systems we can we’re sensitive to surfaces and interfaces we can deal with extremes of sample environment and equally importantly that the neutron results actually complement or the scattering techniques you might have with x-rays or more kind of bull characterization tools that you might find in a well-found laboratory hopefully I’ve told you and give you examples about the relevance of global challenge science and I think I think they’re really driving at the at a real frontier unti here which is driven by complexity so but actually we want to extract simplicity from complexity it’s relatively easy to go from simplicity to complexity able to extract simplicity from complexity is a rather difficult thing and have an atomic four dimensional information both reciprocals momentum space and energy space is

really important and actually the role of high-performance computer modeling is going to be key one has the impression now that our ability our experimental data is beyond some of the areas of numerical calculation so we need to make sure the consistent approach if we’re going to to make that virtual surface that virtual circle complete and I’d like to finish by just saying that we really are only skimming the surface is what is capable with these techniques so I would like to thank my colleagues that Isis has shown here and I would like to stop there and thank you for your attention