̽��ֱ�� of Cambridge - Materials Science

“Elegant” algae solution wins Cambridge Zero student Climate Challenge

plc32 — Mon, 13 Mar 2023 16:02:58 +0000

Team AlgaeSorb’s winning pitch persuaded a panel of innovation experts to award them the top prize of £1500 for an idea, which judge Dr Nicky Dee, Founder of climate-focused venture capital group Carbon13, described as “elegant”.

“ ̽��ֱ��Climate Challenge was an incredible opportunity to not only meet like-minded students, but learn invaluable skills on crafting and designing impact-driven projects,” said Team AlgaeSorb’s Anish Chaluvadi, a Gates-Cambridge Scholar and Nanoscience and Nanotechnology PhD student at King’s College.

̽��ֱ��team also includes Nanoscience and Nanotechnology PhD student Timothy Lambden (Girton College) and Tristan Spreng, a Natural Sciences Masters’ student (Trinity College) and President of the Cambridge ̽��ֱ�� Energy Technology Society.

“ ̽��ֱ��Climate Challenge was one of the most exciting and well-organised events I got to attend during my four years at Cambridge," Spreng said. "From the breadth of speakers at the seminar sessions to exchanging ideas with other participants during the launch and final events, it was a truly amazing experience.”

Eight teams gathered in the Cambridge Institute for Sustainability Leadership’s (CISL) newly retro-fitted Entopia building to pitch ideas ranging from using machine learning to create algorithms for flood risk to crunching satellite data for locating wall-mounted solar panels.

̽��ֱ��judging panel also included serial entrepreneur Simon Hombersley, Professor Jaideep Prabhu, the Jawaharlal Nehru Professor of Indian Business and Enterprise at the Cambridge Judge Business School, Lindsay Hooper, Executive Director of CISL and Chris Gibbs from the ̽��ֱ��’s technology transfer unit Cambridge Enterprise.

Dr Dee said AlgaeSorb was a brilliant entry by a mixed team, which drew on different country experiences and expertise across chemistry, physics and materials sciences.

“As a result they developed an elegant solution to tackle methane in the Global South where other landfill solutions are not available and in a way that supports the local communities,” she said.

In between pitches, experts such as Professor Prabhu and Cambridge Zero Director Professor Emily Shuckburgh offered insights on sustainable innovation and its importance in the race to reduce greenhouse gas emissions and keep global temperatures below 1.5 degrees Celsius.

Dr Amy Munro-Faure, Cambridge Zero’s Head of Education and Student Engagement led a quick game that mixed teams for spontaneous pitches, which resulted in a wild melange of ideas that included saving dolphins and travelling through time.

̽��ֱ��eight-week Climate Challenge programme is run in partnership with CISL Canopy, Carbon13, Energy IRC, Cambridge Enterprise, the Maxwell Centre and sponsored by Moda Living. Competing teams undertake training and develop early-stage proposals for solutions to tackle climate challenges in innovative ways.

Each year there is a new theme. This year’s theme, “A Just Transition”, asked teams to consider the social impacts of their climate solutions.

Two runner-up teams were awarded a prize of £750. FireSight, formed of Jovana Knezevic and Onkar Gulati, pitched a risk assessment and consulting service to address global wildfires using remote sensing and machine learning. Carolina Pulignani and Shannon A. Bonke of Wastevalor fascinated the judges with their technology that converts waste into methanol.

Team Reckon, made up of Aparna Holenarasipura Sreedhara and Akanksha Sahay, won the Audience Choice Award for their software as a service platform entry. ̽��ֱ��software gives organisations the ability to measure the social impact of their climate transition plans.

Judges said the Climate Challenge was a powerful demonstration of how innovation and the determination to tackle climate change permeate every level of the Cambridge ̽��ֱ�� community.

“Helping build the entrepreneurial mindset in the ̽��ֱ�� ecosystem is critical to the innovation agenda and particularly crucial for a true net zero where over half the innovations needed for 2050 are still in the lab,” Gibbs said.

A team of student entrepreneurs who see algae as a potential business solution for reducing methane emissions from landfill and waste-water sites won the 2023 Cambridge Zero Climate Challenge after a nail-biting competition.

̽��ֱ��climate challenge was one of the most exciting and well-organised events I got to attend during my four years at Cambridge

Tristan Spreng

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Bamboo bats... Howzat?!

ta385 — Mon, 10 May 2021 05:00:00 +0000

Cricket bats should be made from bamboo rather than traditional willow, say researchers from Cambridge’s Centre for Natural Material Innovation. Extensive tests showed that bamboo performs better than willow as well as being more sustainable and cheaper.

Next-generation smartphone battery inspired by the gut

sc604 — Wed, 26 Oct 2016 13:41:29 +0000

Researchers have developed a prototype of a next-generation lithium-sulphur battery which takes its inspiration in part from the cells lining the human intestine. ̽��ֱ��batteries, if commercially developed, would have five times the energy density of the lithium-ion batteries used in smartphones and other electronics.

̽��ֱ��new design, by researchers from the ̽��ֱ�� of Cambridge, overcomes one of the key technical problems hindering the commercial development of lithium-sulphur batteries, by preventing the degradation of the battery caused by the loss of material within it. ̽��ֱ��results are reported in the journal Advanced Functional Materials.

Working with collaborators at the Beijing Institute of Technology, the Cambridge researchers based in Dr Vasant Kumar’s team in the Department of Materials Science and Metallurgy developed and tested a lightweight nanostructured material which resembles villi, the finger-like protrusions which line the small intestine. In the human body, villi are used to absorb the products of digestion and increase the surface area over which this process can take place.

In the new lithium-sulphur battery, a layer of material with a villi-like structure, made from tiny zinc oxide wires, is placed on the surface of one of the battery’s electrodes. This can trap fragments of the active material when they break off, keeping them electrochemically accessible and allowing the material to be reused.

“It’s a tiny thing, this layer, but it’s important,” said study co-author Dr Paul Coxon from Cambridge’s Department of Materials Science and Metallurgy. “This gets us a long way through the bottleneck which is preventing the development of better batteries.”

A typical lithium-ion battery is made of three separate components: an anode (negative electrode), a cathode (positive electrode) and an electrolyte in the middle. ̽��ֱ��most common materials for the anode and cathode are graphite and lithium cobalt oxide respectively, which both have layered structures. Positively-charged lithium ions move back and forth from the cathode, through the electrolyte and into the anode.

̽��ֱ��crystal structure of the electrode materials determines how much energy can be squeezed into the battery. For example, due to the atomic structure of carbon, each carbon atom can take on six lithium ions, limiting the maximum capacity of the battery.

Sulphur and lithium react differently, via a multi-electron transfer mechanism meaning that elemental sulphur can offer a much higher theoretical capacity, resulting in a lithium-sulphur battery with much higher energy density. However, when the battery discharges, the lithium and sulphur interact and the ring-like sulphur molecules transform into chain-like structures, known as a poly-sulphides. As the battery undergoes several charge-discharge cycles, bits of the poly-sulphide can go into the electrolyte, so that over time the battery gradually loses active material.

̽��ֱ��Cambridge researchers have created a functional layer which lies on top of the cathode and fixes the active material to a conductive framework so the active material can be reused. ̽��ֱ��layer is made up of tiny, one-dimensional zinc oxide nanowires grown on a scaffold. ̽��ֱ��concept was trialled using commercially-available nickel foam for support. After successful results, the foam was replaced by a lightweight carbon fibre mat to reduce the battery’s overall weight.

“Changing from stiff nickel foam to flexible carbon fibre mat makes the layer mimic the way small intestine works even further,” said study co-author Dr Yingjun Liu.

This functional layer, like the intestinal villi it resembles, has a very high surface area. ̽��ֱ��material has a very strong chemical bond with the poly-sulphides, allowing the active material to be used for longer, greatly increasing the lifespan of the battery.

“This is the first time a chemically functional layer with a well-organised nano-architecture has been proposed to trap and reuse the dissolved active materials during battery charging and discharging,” said the study’s lead author Teng Zhao, a PhD student from the Department of Materials Science & Metallurgy. “By taking our inspiration from the natural world, we were able to come up with a solution that we hope will accelerate the development of next-generation batteries.”

For the time being, the device is a proof of principle, so commercially-available lithium-sulphur batteries are still some years away. Additionally, while the number of times the battery can be charged and discharged has been improved, it is still not able to go through as many charge cycles as a lithium-ion battery. However, since a lithium-sulphur battery does not need to be charged as often as a lithium-ion battery, it may be the case that the increase in energy density cancels out the lower total number of charge-discharge cycles.

“This is a way of getting around one of those awkward little problems that affects all of us,” said Coxon. “We’re all tied in to our electronic devices – ultimately, we’re just trying to make those devices work better, hopefully making our lives a little bit nicer.”

Reference:
Teng Zhao et al. ‘Advanced Lithium-Sulfur Batteries Enabled by a Bio-Inspired Polysulfide Adsorptive Brush.’ Advanced Functional Materials (2016). DOI: 10.1002/adfm.201604069

A new prototype of a lithium-sulphur battery – which could have five times the energy density of a typical lithium-ion battery – overcomes one of the key hurdles preventing their commercial development by mimicking the structure of the cells which allow us to absorb nutrients.

This gets us a long way through the bottleneck which is preventing the development of better batteries.

Paul Coxon

Teng Zhao

Computer visualisation of villi-like battery material

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Fingerprinting rare earth elements from the air

lw355 — Fri, 01 Jul 2016 09:00:00 +0000

Next time you use your mobile phone, spare a moment for the tiny yet vital ingredients that make this and many other technologies possible – the rare earth elements (REEs).

Used in computers, fibre optic cables, aircraft components and even the anti-counterfeiting system in euro notes, these materials are crucial for an estimated £3 trillion worth of industries, with demand set to increase over the coming decades.

Currently, more than 95% of the global demand for the REEs is met by a single mine in China. ̽��ֱ��security of the future supply of these 17 critical metals, which include neodymium, europium, terbium, dysprosium and yttrium, is a major concern for European governments, and the identification of potential REE resources outside China is seen as a high priority.

Over the past year, Drs Sally Gibson, Teal Riley and David Neave have been working together through a ̽��ֱ�� of Cambridge–BAS Joint Innovation Project (see panel) on a remote sensing technique that could aid the identification of REEs in rocks anywhere in the world. ̽��ֱ��project brings together expertise in remote sensing, geochemistry and mineralogy from both institutes to take advantage of the properties that make the metals so special.

“Despite their name, the rare earth elements are not particularly rare and are as abundant in the Earth’s crust as elements such as copper and tin,” explains Riley from BAS. “However, to be extractable in an economic way, they need to be concentrated into veins or sediments.” It’s the identification of these concentrations that is critical for the future security of supply. REEs all have an atomic structure that causes them to react to photons of light through a series of electronic transitions. This gives them the magnetic and electrical properties for which they are prized in plasma TVs, wind turbines and electric car batteries. And it also means that for every photon of light they absorb, they reflect other photons in a unique way – it is this property that the researchers have latched onto as a means of tracking them down.

“ ̽��ֱ��light they reflect is so specific that it’s like a fingerprint, one that we can capture using sensors that pick up light emissions,” explains Gibson, from Cambridge’s Department of Earth Sciences. “ ̽��ֱ��difficulty, however, is that in naturally occurring rocks and minerals, the rare earth element emission spectra are mixed up with those of other elements. It’s like looking at overlapping fingerprints – the challenge was to work out how to tease these spectral fingerprints apart.”

Gibson has over 20 years’ experience investigating how REEs are generated during the melting of the Earth’s mantle. “Collective understanding of the geological make-up of the world is now good enough that we know where to look for these rocks – at sites of a certain type of past tectonic activity – but even then it’s difficult to find them.”

Riley is the head of the Geological Mapping Group at BAS – his job is to “map the unmapped” areas of the polar region to understand the geological evolution of the continent. Much of his work depends on being able to develop new ways of interrogating satellite- and aircraft-based remote sensing data. “It became a frustration that we could collect data and say generally what was on the ground but that we couldn’t define individual fingerprints, and so we developed the analytical tools to do this.”

Gibson and Neave gathered rocks containing REE-bearing minerals from around the world – sourced from mining companies, museum collections and universities. One such source was the Harker Collection housed in the ̽��ֱ��’s Sedgwick Museum of Earth Sciences. This collection contains specimens of minerals and rocks rich in REEs that were collected decades previously by geologists who were unaware of their economic importance.

Neave analysed the emission spectrum of each rock and related this to its gross and microscopic composition. From this information he began to untangle the individual fingerprints, resulting in what the researchers believe is the most comprehensive ‘spectral database’ of REEs in their natural state – in rocks.

̽��ֱ��next goal is to use this spectral database as a reference source to track down deposits from the air. “Although data from aircraft is now good enough to be analysed in this way, we are waiting for new satellite missions such as the German Environmental Mapping and Analysis Program (EnMAP) to be launched in the next few years,” explains Riley. ̽��ֱ��plan would then be to carry out reconnaissance sweeps of the most likely terrains and explore the possibility of mining these areas. “Our hope is that this research will help to create an internationally unique and competitive capability to map these surprisingly common – yet difficult to find – materials,” adds Gibson.

Vital to many modern technologies yet mined in few places, the ‘rare earth elements’ are in fact not that rare – they are just difficult to find in concentrations that make them economic to mine. Researchers from Cambridge ̽��ֱ�� and the British Antarctic Survey (BAS) are investigating whether the remarkable properties of these materials can be used to track them down from the air.

̽��ֱ��light they reflect is so specific that it’s like a fingerprint, one that we can capture using sensors that pick up light emissions

Sally Gibson

Aurora Cambridge

̽��ֱ��search for rare earth elements is one of a host of ongoing projects between the ̽��ֱ�� and BAS. Like these, a new centre – Aurora Cambridge – will reflect the ethos that innovation developed for the Antarctic is transferable to a global setting.

Aurora Cambridge aims to generate new research and entrepreneurial activity focused on climate change and challenging environments through academic, business and policy partnerships. It will be located at BAS in Cambridge and has been funded by the National Environment Research Council with support from the ̽��ֱ��.

̽��ֱ��building is due to open in 2017; however, 27 ̽��ֱ�� of Cambridge–BAS Joint Innovation Projects are already under way with funding from the Higher Education Funding Council for England – including the development of mapping technologies for rare earth elements led by Drs Sally Gibson and Teal Riley.

Other projects include research on cold-adapted enzymes with potential applications in the biotech industries, remote sensing for conservation of seabirds and marine mammals, and the measurement of coastal vulnerability through sea-level rise. Many involve external industrial partners and other research institutions as well as researchers from BAS and 12 ̽��ֱ�� departments.

“ ̽��ֱ��collaborative projects demonstrate not only the importance of research technology to the Antarctic but also their transferability beyond its shores to a global setting,” explains BAS Director of Innovation Dr Beatrix Schlarb-Ridley. “ ̽��ֱ��SPECTRO-ICE project, for instance, has brought scientists at BAS who are concerned with monitoring the atmosphere above the ice cap together with physicists and mathematicians who are working hard to avoid seeing the atmosphere in their study of the stars – both use similar techniques and need to operate advanced instruments at difficult locations.”

“This is just the beginning,” says BAS Director Professor Jane Francis. “ ̽��ֱ��new innovation centre will help us to extend the range of fruitful partnerships with academia, business, policy makers and the third sector to create tangible benefits for society.”

www.bas.ac.uk/aurora-cambridge

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Quantum effects at work in the world’s smelliest superconductor

sc604 — Mon, 28 Mar 2016 15:00:00 +0000

̽��ֱ��quantum behaviour of hydrogen affects the structural properties of hydrogen-rich compounds, which are possible candidates for the elusive room temperature superconductor, according to new research co-authored at the ̽��ֱ�� of Cambridge.

New theoretical results, published online in the journal Nature, suggest that the quantum nature of hydrogen – meaning that it can behave like a particle or a wave – strongly affects the recently discovered hydrogen sulphur superconductor, a compound that when subjected to extremely high pressure, is the highest-temperature superconductor yet identified. This new step towards understanding the underlying physics of high temperature superconductivity may aid in the search for a room temperature superconductor, which could be used for applications such as levitating trains, lossless electrical grids and next-generation supercomputers.

Superconductors are materials that carry electrical current with zero electrical resistance. Low-temperature, or conventional, superconductors were first identified in the early 20th century, but they need to be cooled close to absolute zero (zero degrees on the Kelvin scale, or -273 degrees Celsius) before they start to display superconductivity. For the past century, researchers have been searching for materials that behave as superconductors at higher temperatures, which would make them more suitable for practical applications. ̽��ֱ��ultimate goal is to identify a material which behaves as a superconductor at room temperature.

Last year, German researchers identified the highest temperature superconductor yet – hydrogen sulphide, the same compound that gives rotten eggs their distinctive odour. When subjected to extreme pressure – about one million times higher than the Earth’s atmospheric pressure – this stinky compound displays superconducting behaviour at temperatures as high as 203 Kelvin (-70 degrees Celsius), which is far higher than any other high temperature superconductor yet discovered.

Since this discovery, researchers have attempted to understand what it is about hydrogen sulphide that makes it capable of superconducting at such high temperatures. Now, new theoretical results suggest that the quantum behaviour of hydrogen may be the reason, as it changes the structure of the chemical bonds between atoms. ̽��ֱ��results were obtained by an international collaboration of researchers led by the ̽��ֱ�� of the Basque Country and the Donostia International Physics Center, and including researchers from the ̽��ֱ�� of Cambridge.

̽��ֱ��behaviour of objects in our daily life is governed by classical, or Newtonian, physics. If an object is moving, we can measure both its position and momentum, to determine where an object is going and how long it will take to get there. ̽��ֱ��two properties are inherently linked.

However, in the strange world of quantum physics, things are different. According to a rule known as Heisenberg’s uncertainty principle, in any situation in which a particle has two linked properties, only one can be measured and the other must be uncertain.

Hydrogen, being the lightest element of the periodic table, is the atom most strongly subjected to quantum behaviour. Its quantum nature affects structural and physical properties of many hydrogen compounds. An example is high-pressure ice, where quantum fluctuations of the proton lead to a change in the way that the molecules are held together, so that the chemical bonds between atoms become symmetrical.

̽��ֱ��researchers behind the current study believe that a similar quantum hydrogen-bond symmetrisation occurs in the hydrogen sulphide superconductor.

Theoretical models that treat hydrogen atoms as classical particles predict that at extremely high pressures – even higher than those used by the German researchers for their record-breaking superconductor – the atoms sit exactly halfway between two sulphur atoms, making a fully symmetrical structure. However, at lower pressures, hydrogen atoms move to an off-centre position, forming one shorter and one longer bond.

̽��ֱ��researchers have found that when considering the hydrogen atoms as quantum particles behaving like waves, they form symmetrical bonds at much lower pressures – around the same as those used for the German-led experiment, meaning that quantum physics, and symmetrical hydrogen bonds, were behind the record-breaking superconductivity.

“That we are able to make quantitative predictions with such a good agreement with the experiments is exciting and means that computation can be confidently used to accelerate the discovery of high temperature superconductors,” said study co-author Professor Chris Pickard of Cambridge’s Department of Materials Science & Metallurgy.

According to the researcher’s calculations, the quantum symmetrisation of the hydrogen bond has a tremendous impact on the vibrational and superconducting properties of hydrogen sulphide. “In order to theoretically reproduce the observed pressure dependence of the superconducting critical temperature the quantum symmetrisation needs to be taken into account,” said the study’s first author, Ion Errea, from the ̽��ֱ�� of the Basque Country and Donostia International Physics Center.

̽��ֱ��discovery of such a high temperature superconductor suggests that room temperature superconductivity might be possible in other hydrogen-rich compounds. ̽��ֱ��current theoretical study shows that in all these compounds, the quantum motion of hydrogen can strongly affect the structural properties, even modifying the chemical bonding, and the electron-phonon interaction that drives the superconducting transition.

“Theory and computation have played an important role in the hunt for superconducting hydrides under extreme compression,” said Pickard. “ ̽��ֱ��challenges for the future are twofold - increasing the temperature towards room temperature, but, more importantly, dramatically reducing the pressures required.”

Reference:
Ion Errea et. al. ‘Quantum hydrogen-bond symmetrization in the superconducting hydrogen sulfide system.’ Nature (2016).DOI: 10.1038/nature17175.

Researchers have found that quantum effects are the reason that hydrogen sulphide – which has the distinct smell of rotten eggs –behaves as a superconductor at record-breaking temperatures, which may aid in the search for room temperature superconductors.

That we are able to make quantitative predictions with such a good agreement with the experiments is exciting and means that computation can be confidently used to accelerate the discovery of high temperature superconductors.

Chris Pickard

UPV/EHU

Structure with symmetric hydrogen bonds induced by the quantum behavior of the protons, represented by the fluctuating blue spheroids

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Opinion: Harder than diamond: have scientists really found something tougher than nature’s invincible material?

Anonymous — Tue, 19 Jan 2016 14:00:25 +0000

Ask most people what the hardest material on Earth is and they will probably answer “diamond”. Its name comes from the Greek word ἀδάμας (adámas) meaning “unbreakable” or “invincible” and is from where we get the word “adamant”. Diamond’s hardness gives it incredible cutting abilities that – along with its beauty – have kept it in high demand for thousands of years.

Modern scientists have spent decades looking for cheaper, harder and more practical alternatives and every few years the news heralds the creation of a new “world’s hardest material”. But are any of these challengers really up to scratch?

Despite its unique allure, diamond is simply a special form, or “allotrope”, of carbon. There are several allotropes in the carbon family including carbon nanotubes, amorphous carbon, diamond and graphite. All are made up of carbon atoms, but the types of atomic bonds between them differ which gives rise to different material structures and properties.

̽��ֱ��outermost shell of each carbon atom has four electrons. In diamond, these electrons are shared with four other carbon atoms to form very strong chemical bonds resulting in an extremely rigid tetrahedral crystal. It is this simple, tightly-bonded arrangement that makes diamond one of the hardest substances on Earth.

How hard?

Vickers test anvil. R Tanaka, CC BY

Hardness is an important property of materials and often determines what they can be used for, but it is also quite difficult to define. For minerals, scratch hardness is a measure of how resistant it is to being scratched by another mineral.

There are several ways of measuring hardness but typically an instrument is used to make a dent in the material’s surface. ̽��ֱ��ratio between the surface area of the indentation and the force used to make it produces a hardness value. ̽��ֱ��harder the material, the larger the value. ̽��ֱ��Vickers hardness test uses a square-based pyramid diamond tip to make the indent.

Mild steel has a Vickers hardness value of around 9 GPa while diamond has a Vickers hardness value of around 70 – 100 GPa. Diamond’s resistance against wear is legendary and today 70% of the world’s natural diamonds are found in wear-resistant coatings for tools used in cutting, drilling and grinding, or as additives to abrasives.

̽��ֱ��problem with diamond is that, while it may be very hard, it is also surprisingly unstable. When diamond is heated above 800℃ in air its chemical properties change, affecting its strength and enabling it to react with iron, which makes it unsuitable for machining steel.

These limits on its use have led to a growing focus on developing new, chemically-stable, superhard materials as a replacement. Better wear-resistant coatings allow industrial tools to last longer between replacing worn parts and reduce the need for potentially environmentally-hazardous coolants. Scientists have so far managed to come up with several potential rivals to diamond.

Boron nitride

Microscopic BN crystal. NIMSoffice/Wikimedia Commons

̽��ֱ��synthetic material boron nitride, first produced in 1957, is similar to carbon in that it has several allotropes. In its cubic form (c-BN) it shares the same crystalline structure as diamond, but instead of carbon atoms is made up of alternately-bonded atoms of boron and nitrogen. c-BN is chemically and thermally stable, and is commonly used today as a superhard machine tool coating in the automotive and aerospace industries.

But cubic boron nitride is still, at best, just the world’s second hardest material with a Vickers hardness of around 50 GPa. Its hexagonal form (w-BN) was initially reported to be even harder but these results were based upon theoretical simulations that predicted an indentation strength 18% higher than diamond. Unfortunately w-BN is extremely rare in nature and difficult to produce in sufficient quantities to properly test this claim by experiment.

Synthetic diamond

Synthetic diamond closeup. Instytut Fizyki Uniwersytet Kazimierza Wielkiego, CC BY

Synthetic diamond has also been around since the 1950s and is often reported to be harder than natural diamond because of its different crystal structure. It can be produced by applying high pressure and temperature to graphite to force its structure to rearrange into the tetrahedral diamond, but this is slow and expensive. Another method is to effectively build it up with carbon atoms taken from heated hydrocarbon gases but the types of substrate material you can use are limited.

Producing diamonds synthetically creates stones that are polycrystalline and made up of aggregates of much smaller crystallites or “grains” ranging from a few microns down to several nanometers in size. This contrasts with the large monocrystals of most natural diamonds used for jewellery. ̽��ֱ��smaller the grain size, the more grain boundaries and the harder the material. Recent research on some synthetic diamond has shown it to have a Vickers hardness of up to 200 GPa.

Q-carbon

Q-Carbon closeup. North Carolina State ̽��ֱ��

More recently, researchers at North Carolina State ̽��ֱ�� created what they described as a new form of carbon, distinct from other allotropes, and reported to be harder than diamond. This new form was made by heating non-crystalline carbon with a high-powered fast laser pulse to 3,700 °C then quickly cooling or “quenching” it – hence the name “Q-carbon” – to form micron-sized diamonds.

̽��ֱ��scientists found Q-carbon to be 60% harder than diamond-like carbon (a type of amorphous carbon with similar properties to diamond). This has led them to expect Q-carbon to be harder than diamond itself, although this still remains to be proven experimentally. Q-carbon also has the unusual properties of being magnetic and glowing when exposed to light. But so far it’s main use has been as an intermediate step in producing tiny synthetic diamond particles at room temperature and pressure. These nanodiamonds are too small for jewellery but ideal as a cheap coating material for cutting and polishing tools.

Paul Coxon, Postdoctoral research associate, ̽��ֱ�� of Cambridge

This article was originally published on ̽��ֱ��Conversation. Read the original article.

̽��ֱ��opinions expressed in this article are those of the individual author(s) and do not represent the views of the ̽��ֱ�� of Cambridge.

Paul Coxon (Department of Materials Science and Metallurgy) discusses the materials that have each been heralded as the new “world’s hardest material”.

Judy van der Velden

Diamonds

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Licence type:

Attribution-Noncommercial-ShareAlike

New understanding of how shape and form develop in nature

sc604 — Wed, 09 Dec 2015 18:01:07 +0000

Researchers have developed a new method for generating complex shapes, and have found that the development of form in nature can be driven by the physical properties of materials themselves, in contrast with earlier findings. ̽��ֱ��results, reported in the journal Nature, could enable the construction of complex structures from simple components, with potential applications in pharmaceuticals, paints, cosmetics and household products such as shampoo.

Using a simple set-up – essentially droplets of oil in a soapy water solution which were slowly frozen – the researchers found that recently-discovered ‘plastic crystal’ phases formed on the inside surfaces of the droplets causes them to shape-shift into a wide variety of forms, from octahedrons and hexagons to triangles and fibres.

Previous efforts to create such complex shapes and structures have used top-down processing methods, which allow a high degree of control, but are not efficient in terms of the amount of material used or the expensive equipment necessary to make the shapes. ̽��ֱ��new method, developed by researchers from the ̽��ֱ�� of Cambridge and Sofia ̽��ֱ�� in Bulgaria, uses a highly efficient, extremely simple bottom-up approach to create complex shapes.

“There are many ways that non-biological things take shape,” said Dr Stoyan Smoukov from Cambridge’s Department of Materials Science & Metallurgy, who led the research. “But the question is what drives the process and how to control it – and what are the links between the process in the biological and the non-biological world?”

Smoukov’s research proposes a possible answer to the question of what drives this process, called morphogenesis. In animals, morphogenesis controls the distribution of cells during embryonic development, and can also be seen in mature animals, such as in a growing tumour.

In the 1950s, the codebreaker and mathematician Alan Turing proposed that morphogenesis is driven by reaction-diffusion, in which local chemical reactions cause a substance to spread through a space. More recent research, from Smoukov’s group and others, has proposed that it is physical properties of materials that control the process. This possibility had been anticipated by Turing, but it was impossible to determine using the computers of the time.

What this most recent research has found is that by slowly freezing oil droplets in a soapy solution, the droplets will shape-shift through a variety of different forms, and can shift back to their original shape if the solution is re-warmed. Further observation found that this process is driven by the self-assembly of a plastic crystal phase which forms beneath the surface of the droplets.

“Plastic crystals are a special state of matter that is like the alter ego of the liquid crystals used in many TV screens,” said Smoukov. Both liquid crystals and plastic crystals can be thought of as transitional stages between liquid and solid. While liquid crystals point their molecules in defined directions like a crystal, they have no long-range order and flow like a liquid. Plastic crystals are wax-like with long-range order in their molecular arrangement, but disorder in the orientation of each molecule. ̽��ֱ��orientational disorder makes plastic crystals highly deformable, and as they change shape, the droplets change shape along with them.

“This plastic crystal phase seems to be what’s causing the droplets to change shape, or break their symmetry,” said Smoukov. “And in order to understand morphogenesis, it’s vital that we understand what causes symmetry breaking.”

̽��ֱ��researchers found that by altering the size of the droplets they started with or the rate that the temperature of the soapy solution was lowered, they were able to control the sequence of the shapes the droplets ended up forming. This degree of control could be useful for multiple applications – from pharmaceuticals to household goods – that use small-droplet emulsions.

“ ̽��ֱ��plastic crystal phase has been of intense scientific interest recently, but no one so far has been able to harness it to exert forces or show this variety of shape-changes,” said the paper’s lead author Professor Nikolai Denkov of Sofia ̽��ֱ��, who first proposed the general explanation of the observed transformations.

“ ̽��ֱ��phenomenon is so rich in combining several active areas of research that this study may open up new avenues for research in soft matter and materials science,” said co-author Professor Slavka Tcholakova, also of Sofia ̽��ֱ��.

“If we’re going to build artificial structures with the same sort of control and complexity as biological systems, we need to develop efficient bottom-up processes to create building blocks of various shapes, which can then be used to make more complicated structures,” said Smoukov. “But it’s curious to observe such life-like behaviour in a non-living thing – in many cases, artificial objects can look more ‘alive’ than living ones.”

Inset image: Morphogenesis ( ̽��ֱ�� of Cambridge).

Reference:
Denkov, Nikolai et. al. ‘Self-Shaping of Droplets via Formation of Intermediate Rotator Phases upon Cooling.’ Nature (2015). DOI: 10.1038/nature16189.

Researchers have identified a new mechanism that drives the development of form and structure, through the observation of artificial materials that shape-shift through a wide variety of forms which are as complex as those seen in nature.

It’s curious to observe such life-like behaviour in a non-living thing – in many cases, artificial objects can look more ‘alive’ than living ones

Stoyan Smoukov

̽��ֱ�� of Cambridge

Morphogenesis

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Engineering atoms inside the jet engine: the Great British Take Off

lw355 — Mon, 29 Jun 2015 07:30:21 +0000

Inside a jet engine is one of the most extreme environments known to engineering.

In less than a second, a tonne of air is sucked into the engine, squeezed to a fraction of its normal volume and then passed across hundreds of blades rotating at speeds of up to 10,000 rpm; reaching the combustor, the air is mixed with kerosene and ignited; the resulting gases are about a third as hot as the sun’s surface and hurtle at speeds of almost 1,500 km per hour towards a wall of turbines, where each blade generates power equivalent to the thrust of a Formula One racing car.

Turbine blades made from ‘super’ materials with outstanding properties are needed to withstand these unimaginably challenging conditions – where the temperatures soar to above the melting point of the turbine components and the centrifugal forces are equivalent to hanging a double-decker bus from each blade.

Even with these qualities, the blades require a ceramic layer and an air cooling system to prevent them from melting when the engine reaches its top temperatures. But with ever-increasing demands for greater performance and reduced emissions, the aerospace industry needs engines to run even hotter and faster, and this means expecting more and more from the materials they are made from.

This, says Dr Cathie Rae, is the materials grand challenge. “Turbine blades are made using nickel-based superalloys, which are capable of withstanding the phenomenal stresses and temperatures they need to operate under within the jet engine. But we are running close to their critical limits.”

An alloy is a mixture of metals, such as you might find in steel or brass. A superalloy, however, is a mixture that imparts superior mechanical strength and resistance to heat-induced deformation and corrosion.

Rae is one of a team of scientists in the Rolls-Royce ̽��ֱ�� Technology Centre (UTC) at the Department of Materials Science and Metallurgy. ̽��ֱ��team’s research efforts are focused on extracting the greatest possible performance from nickel-based superalloys, and on designing superalloys of the future.

Current jet engines predominantly use alloys containing nickel and aluminium, which form a strong cuboidal lattice. Within and around this brick-like structure are up to eight other components that form a ‘mortar’. Together, the components give the material its superior qualities.

“Even tiny adjustments in the amount of each component can have a huge effect on the microscopic structure, and this can cause radical changes in the superalloy’s properties,” explains Dr Howard Stone. “It’s rather like adjusting the ingredients in a cake – increasing one ingredient might produce one sought-after property, but at the sake of another. We need to find the perfect chemical recipe.”

Stone is the Principal Investigator overseeing a £50 million Strategic Partnership on structural metallic systems for advanced gas turbine applications funded jointly by Rolls-Royce and the Engineering and Physical Sciences Research Council (EPSRC), and involving the Universities of Birmingham, Swansea, Manchester, Oxford and Sheffield, and Imperial College London.

̽��ֱ��researchers melt together precise amounts of each of the different elements to obtain a 5cm bar, then exhaustively test the bar’s mechanical properties and analyse its microscopic structure. Their past experience in atomic engineering is vital for homing in on where the incremental improvements might be found – without this, they would need to make many millions of bars to test each reasonable mixture of components.

Now, they are looking beyond the usual components to exotic elements, although always with an eye on keeping costs as low as possible, which means not using extremely rare materials. “ ̽��ֱ��Periodic Table is our playground… we’re picking and mixing elements, guided by our computer models and experimental experience, to find the next generation of superalloys,” he adds.

̽��ֱ��team now have 12 patents with Rolls-Royce. One of the most recent has been in collaboration with Imperial College London, and involves the discovery that the extremely strong matrix structure of nickel-based aluminium superalloys can also be achieved using a mixture of nickel, aluminium, cobalt and tungsten.

“Instead of the cake being flavoured with two main ingredients, we can make it with four,” Stone explains. “This gives the structure even better properties, many of which we are only just discovering.”

“We’ve also been looking at new intermetallic reinforced superalloys using chromium, tantalum and silicon – no nickel at all. We haven’t quite got the final balance to achieve what we want, but we’re working towards it.”

Stone highlights the importance of collaboration between industry and academia: “New alloys typically take 10 years and many millions of pounds to develop for operational components. We simply couldn’t do this work without Rolls-Royce. For the best part of two decades we’ve had a collaboration that links fundamental materials research through to industrial application and commercial exploitation.”

It’s a sentiment echoed by Dr Justin Burrows, Project Manager at Rolls-Royce: “Our academic partners understand the materials and design challenges we face in the development of gas turbine technology. Improvements like the novel nickel and steel alloys developed in Cambridge are key to helping us meet these challenges and to maintaining our competitive advantage.”

̽��ֱ��Cambridge UTC, which was founded by its Director Professor Sir Colin Humphreys in 1994, is one of a global network of over 30 UTCs. These form part of Rolls-Royce’s £1 billion annual investment in research and development, which also includes the Department of Engineering’s ̽��ֱ�� Gas Turbine Partnership. Rolls-Royce and EPSRC also fund Doctoral Training Centres in Cambridge that help to ensure a continuing supply of highly trained scientists and engineers ready to move into industry.

̽��ֱ��UK aerospace industry is the largest in Europe, with a turnover in 2011 of £24.2 billion; worldwide, it’s second only to that of the USA. Meanwhile, increasing global air traffic is estimated to require 35,000 new passenger aircraft by 2030, worth about $4.8 trillion.

For the researchers, it’s fascinating to see global engineering challenges being solved from the atom up, as Rae explains: “ ̽��ֱ��commercial success of a new engine can be dependent on very small differences in fuel efficiency, which can only be achieved by innovations in materials and design. There’s something really exciting about working at the atomic scale and seeing this translate into innovation with big powerful machines.”

Inset image: Thermo cycling.

̽��ֱ��Periodic Table may not sound like a list of ingredients but, for a group of materials scientists, it’s the starting point for designing the perfect chemical make-up of tomorrow’s jet engines.

Increasing one ingredient might produce one sought-after property, but at the sake of another – we need to find the perfect chemical recipe

Howard Stone

Engineering Atoms

Rolls-Royce Plc

Rotor

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes