Perovskite understanding could lead to novel solar cell materials
In a discovery that could have profound implications for future energy policy, scientists at Columbia University have demonstrated that it is possible to manufacture solar cells that are far more efficient than existing silicon-based cells by using a new kind of material.
The team, led by Xiaoyang Zhu, a professor of chemistry at Columbia University, focused its efforts on a new class of solar cell material known as hybrid organic inorganic perovskites (HOIPs). Their results, reported in Science, also explain why these new materials are so much more efficient than traditional solar cells – solving a mystery that will likely prompt scientists and engineers to begin inventing new solar cell materials with similar properties in the years ahead.
“The need for renewable energy has motivated extensive research into solar cell technologies that are economically competitive with burning fossil fuel,” Zhu says. “Among the materials being explored for next generation solar cells, HOIPs have emerged a superstar. Until now no one has been able to explain why they work so well, and how much better we might make them. We now know it’s possible to make HOIP-based solar cells even more efficient than anyone thought possible.”
Solar cells turn sunlight into electricity. Also known as photovoltaic cells, these semiconductors are most frequently made from thin layers of silicon that transmit energy across their structure to generate an electrical current.
Silicon panels, which currently dominate the market for solar panels, must have a purity of 99.999%, and are notoriously fragile and expensive to manufacture. Even a microscopic defect – such as misplaced, missing or extra ions – in this crystalline structure can exert a powerful pull on the charges the cells generate when they absorb sunlight, dissipating those charges before they can be transformed into electrical current.
In 2009, Japanese scientists demonstrated that it was possible to build solar cells out of HOIPs, and that these cells could harvest energy from sunlight even when the crystals possessed a significant number of defects. Because they don’t need to be pristine, HOIPs can be produced on a large scale and at low cost. The Columbia team has been investigating HOIPs since 2014.
This shows we can push the efficiencies of solar cells much higher than many people thought possible.Xiaoyang Zhu, Columbia University
Over the past seven years, scientists have managed to increase the efficiency with which HOIPs can convert solar energy into electricity from 4% to 22%. By contrast, it took researchers more than six decades to create silicon cells and bring them to their current level, and even now silicon cells can convert no more than about 25% of the sun’s energy into electrical current.
According to Zhu, this means that “scientists have only just begun to tap the potential of HOIPs to convert the sun’s energy into electricity”.
Theorists long ago calculated that the maximum efficiency silicon solar cells might ever reach – the percentage of energy in sunlight that might be converted to electricity – is roughly 33%. It takes hundreds of nanoseconds for energized electrons to move from the part of a solar cell that infuses them with the sun’s energy to the part of the cell that harvests the energy and converts it into electricity. During this migration across the solar cell, the energized electrons quickly dissipate their excess energy, limiting the conversion efficiency.
These calculations, however, assume a specific rate of energy loss. The Columbia team has discovered that the rate of energy loss is slowed down by over three-orders of magnitude in HOIPs – making it possible to harvest excess electronic energy to increase the efficiency of solar cells.
“We’re talking about potentially doubling the efficiency of solar cells,” says Prakriti Joshi, a PhD student in Zhu’s lab who is a co-author on the paper. “That’s really exciting because it opens up a big, big field in engineering.”
“This shows we can push the efficiencies of solar cells much higher than many people thought possible,” adds Zhu.
The scientists then turned to the next question: what is it about the molecular structure of HOIPs that gives them their unique properties? How do the electrons avoid defects? They discovered that the same mechanism that slows down the cooling of electron energy also protects the electrons from bumping into defects. This ‘protection’ makes the HOIPs turn a blind eye to the ubiquitous defects in a material developed from solution processing at room temperature, thus allowing an imperfect material to behave like a perfect semiconductor.
A major disadvantage of HOIPs is that they contain lead and are water soluble, meaning that solar cells made from HOIPs could begin to dissolve and leach lead into the environment if not carefully protected from the elements. With this new explanation of the mysterious mechanisms that give HOIPs their remarkable efficiencies, however, material scientists may now be able to mimic their abilities with more environmentally-friendly materials.
“Now we can go back and design materials which are environmentally benign and really solve this problem everybody is worried about,” Zhu says. “This principle will allow people to start to design new materials for solar energy.”
This story is adapted from material from Columbia University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
Materials Today outreach at Chinese Institutes
This September, Dr Christiane Barranguet visited BeiHang University, Beijing Institute of Nanoenergy and Nanosystems, Fudan University, and Zhejiang University in China, to explore how Elsevier and Materials Today may better support local researchers.
Dr Barranguet spoke to researchers at all levels, spanning materials science, to find out about the challenges faced by the community in China. Together, topics including open access, funding, local and international conference support, peer review, as well as new journal launches were discussed; with plans already shaping up for 2017 and beyond.
"Chinese universities are among the most productive worldwide, and their impact follows the same trend, leading the way in many emerging fields of materials science," says Dr Barranguet, "Materials Today is committed to supporting Chinese researchers and institutes, both through our extensive journal portfolio and surrounding initiatives".
Materials Today celebrates communication and discovery at New Scientist Live
For four days in September, scientists and engineers took over ExCel London. During this, the inaugural New Scientist Live festival, visitors were treated to everything from Comet 67P and supersonic cars, to probes and 3D printers. Ideas and discovery were the key themes of the festival, and this was reflected in the impressive line-up, that included astronaut Tim Peake, leading researchers, authors, speakers from all sectors of society.
On Friday 23rd September, the Materials Today team hosted their own event at the festival. ‘Materials Today at NSLive’ brought together some of the best of materials science, to talk about topics as diverse as science communication and the use of modelling in materials development. It offered attendees a unique opportunity to network with, and learn from, thought leaders across the materials spectrum, exemplified by the welcome from Prof. Subra Suresh, Chair of the Elsevier Materials Science Council. He emphasized the value of communication between researchers and the public, and urged the diverse crowd to talk about their work more, setting the tone for the day.
The busy London Docklands provided the perfect inspiration for discussions on the role of materials in society, which were kickstarted by the first speaker, Prof Mark Miodownik. As Director of the Institute of Making, Mark is a champion for linking materials research to the arts and humanities. And he made it clear that for him, interdisciplinary research will be the only way to meet the challenges of the 21st Century. He focused on three major problems – energy, cities and health – and talked about the role that materials science has to play in each. Something common to all is the reduction of waste. Speaking specifically about gadgets, he said “Close to half the periodic table is found in your smartphone. At end of life, they're blended together, with most never being reused. That's bonkers.”
A more efficient use of materials was also at the heart of the second talk, from Prof. Abhay Pandit, Director of the Centre for Research in Medical Devices at the National University of Ireland, Galway. He started by putting current biomaterials into the context of the early days of mass manufacturing, “Nylon, silicones and stainless steel were not designed specifically for use in biology. We’re now looking for a better approach.” Part of his work is inspired by his own identity, and the fact that humans are living longer than ever before, “We are an ageing society. By 2050, 1 in 3 will be over 65. That comes with challenges."
Ageing took on a different meaning for the next speaker, Dr. Eleanor Schofield, Head of Conservation and Collections Care at The Mary Rose Trust. She discussed the challenges of treating archaeological samples, and highlighted the importance of collaborations with academia to develop new, improved options. Preserving wood is particularly challenging, as Eleanor described, "We first sprayed the remains of the Mary Rose in polyethylene glycol. Once we'd done that, we could dry it, preserving the structure of the wood for many years to come." Iron nails embedded in the wood come with their own interesting chemistry, as does storing samples – both of which are active research projects that Eleanor is managing.
The morning’s talks were followed by a fascinating and lively panel discussion on science communication. The chair, Dr Michael Weir from the University of Sheffield, was joined by Mark, Abhay, and Eleanor, alongside Dr Alan Leshner, CEO Emeritus of AAAS. They compared notes on what has worked well in the past, and what we’ll need to do in the future to inspire the next generation of materials scientists. All felt confident that there had been a shift in attitudes, and that scientists of all levels were now reaping the benefits of communicating with the public. After ably managing a series of tough questions from the audience, the panel closed the morning’s programme.
The afternoon started with a computer-game-like bang, thanks to Prof. Emma Lundberg, from KTH Royal Institute of Technology. She spoke about the important role that gamers are playing in developing the Human Protein Atlas. Fans of the online game Eve Online have, for several months, been taking part in a citizen science project, to classify patterns in microscope images of proteins. Remarkably, since March, “The gamers have carried out 13 million classifications, and this has led to several new findings which will soon be published”.
Prof. Nikola Marzari uses computers rather differently for his work. As Head of the Laboratory of Theory and Simulation of Materials at EPFL, multiscale modelling is his focus. He talked about the use of informatics in materials discovery, and emphasised the need for accuracy and realistic complexity in the models. One of Nicola’s current interests is nanostructures, “By looking at materials data and binding energies from a range of databases, we’ve identified more than 1800 potential 2D materials”.
This was music to the ears of the day’s final speaker, Prof. Jonathan Coleman, Principal Investigator of the Low-Dimensional Nanostructures group at Trinity College Dublin. His research focuses on graphene and other 2D materials, but his talk was titled ‘kitchen physics’. He took the audience on a whistle-stop-tour of some of his group’s work, including graphene-rubber composites that can continuously measure blood pressure, and extracting graphene using a household blender (which, by the way, needs to be > 150W).
This was followed by an afternoon panel chaired by Laurie Winkless, regular contributor to Materials Today. She was joined by Nikola, along with Prof. David Rugg from Rolls-Royce, and Prof. Sohini Kar-Narayan from the University of Cambridge. The topic up for discussion was discovery and development. The conversation started on the growing link between modelling and experiments in materials science, and approached the question “Will modelling ever replace lab work?” (The answer? No!) The panel also discussed the need for closer connections between academia and industry, and the changing nature of skills that tomorrow’s scientists will need. The audience again had lots of questions, which led to a stimulating discussion.
The programme ended with a poster session, which hugely impressed the judges and the Elsevier Materials Science Council. All agreed that we should feel confident about the future of materials science in the UK. The networking continued into the evening, and it seems that several collaborations were forged over the ‘molecular cocktails’ and 3D printing on offer. Feedback for the event has been overwhelmingly positive, so expect to see another Materials Today event soon!
Two wrongs make a right for novel multiferroic material
Multiferroics – materials that exhibit both magnetic and electric order – are of interest for next-generation computing, but are difficult to create because the conditions conducive to each of these states are usually mutually exclusive. And in most multiferroics found to date, their properties emerge only at extremely low temperatures.
Two years ago, researchers in the labs of Darrell Schlom and Dan Ralph at Cornell University, in collaboration with Ramamoorthy Ramesh at the University of California, Berkeley, published a paper announcing a breakthrough in multiferroics. This involved the only known material in which magnetism can be controlled by applying an electric field at room temperature: the multiferroic bismuth ferrite.
Schlom’s group has now partnered with David Muller and Craig Fennie, also at Cornell University, to take this research a step further. By combining two non-multiferroic materials, the researchers have managed to create a new room-temperature multiferroic.
A paper on this work is published in Nature. The lead authors are: Julia Mundy, a former doctoral student working jointly with Muller and Schlom who’s now a postdoctoral researcher at UC Berkeley; Charles Brooks, a visiting scientist in the Schlom group; and Megan Holtz, a doctoral student in the Muller group. Collaborators hailed from the University of Illinois at Urbana-Champaign, the US National Institute of Standards and Technology, the University of Michigan and Penn State University.
The group engineered thin films of hexagonal lutetium iron oxide (LuFeO3), a material known to be a robust ferroelectric but not strongly magnetic, which consists of alternating single monolayers of lutetium oxide and iron oxide. In contrast, a strong ferrimagnetic form of lutetium iron oxide (LuFe2O4) consists of alternating monolayers of lutetium oxide with double monolayers of iron oxide.
The researchers found that they could combine these two materials at the atomic-scale to create a new compound that was not only multiferroic but had better properties than either of the individual constituents. In particular, adding just one extra monolayer of iron oxide to every 10 atomic repeats of LuFeO3 dramatically changed the properties of the system.
That precision engineering was done via molecular-beam epitaxy (MBE), a specialty of the Schlom lab. A technique Schlom likens to “atomic spray painting”, MBE let the researchers design and assemble the two different materials in layers, a single atom at a time.
The combination of the two materials produced a strongly ferrimagnetic material near room temperature. Tests of this new material at the Lawrence Berkeley National Laboratory (LBNL) Advanced Light Source, in collaboration with co-author Ramesh, revealed that the ferrimagnetic atoms followed the alignment of their ferroelectric neighbors when switched by an electric field.
“It was when our collaborators at LBNL demonstrated electrical control of magnetism in the material that we made that things got super exciting,” Schlom said. “Room-temperature multiferroics are exceedingly rare and only multiferroics that enable electrical control of magnetism are relevant to applications.”
In electronics devices, the advantages of multiferroics include their reversible polarization in response to low-power electric fields – as opposed to heat-generating and power-sapping electrical currents – and their ability to hold their polarized state without the need for continuous power. High-performance memory chips make use of ferroelectric or ferromagnetic materials.
“Our work shows that an entirely different mechanism is active in this new material,” Schlom said, “giving us hope for even better – higher-temperature and stronger – multiferroics for the future.”
This story is adapted from material from Cornell University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
Roll-process technology for flexible electronics
Korean scientists have developed highly productive roll-process technology that can continuously transfer and package a range of large-scale integrated circuits (LSI), a breakthrough that could help realize the next generation of flexible electronics, including application processors, high-density memories and high-speed communication devices. With such roll-processing being seen as a core LSI technology to improve the commercialization of wearable computers, the team resolved previous challenges around the nanofabrication process for plastics and to help realize the interconnection of flexible LSI with flexible displays, batteries and other peripheral devices.
In this study, which was reported in the journal Advanced Materials [Kim et al Adv. Mater. (2016) DOI: 10.1002/adma.201602339], the team, led by Keon Jae Lee from the Korea Advanced Institute of Science and Technology, and with Jae-Hyun Kim from the Korea Institute of Machinery and Materials, fabricated NAND flash memories on bulk silicon wafer using standard processes for making semiconductors, before eliminating the thick handle wafer to leave a nanometer-thick circuit layer. They next simultaneously transferred and interconnected the ultrathin device on a printed circuit board through roll-based thermo-compression bonding using anisotropic conductive film (ACF) as a flexible packaging material. The silicon-based flexible NAND memory was able to show stable memory operations and interconnections even after undergoing severe bending, while the circuitry had significant flexibility and stable ACF interconnections.
Our results may open up new opportunities to integrate silicon-based flexible LSIs on plastics with the ACF packing for roll-based manufacturingKeon Jae Lee
The technology showed outstanding bonding capability for continuous roll-based transfer and excellent flexibility of interconnecting core and peripheral devices. They confirmed the reliable operation of the flexible NAND memory at the circuit level by programming and reading letters in ASCII codes. As Keon Jae Lee points out, “Our results may open up new opportunities to integrate silicon-based flexible LSIs on plastics with the ACF packing for roll-based manufacturing”.
LSI consist of over a thousand nanotransistors integrated for computing, memory and communication, and flexible LSI are key to wearable/flexible computers primarily as their main functions are mostly operated through the integration of high-speed nanoscale transistors. The devices, along with the flexible display and communication technology, can be interconnected each other for potential innovative future flexible consumer electronics such as rollable computers, wearable smart devices, and implantable small, thin, flexible, non-breakable, light biomedical devices.
The scientists are now looking at how to realize fully operational flexible electronic systems, including the integrated components of flexible LSIs, displays, batteries and other devices, to demonstrate the credibility of mass commercialization of flexible electronics.
GE to invest $1.4 billion in 3D printing
GE has confirmed its plans to acquire two suppliers of additive manufacturing (AM) equipment, Arcam AB and SLM Solutions Group AG for US$1.4 billion. Both companies will report to David Joyce, president & CEO of GE Aviation, who will lead the growth of these businesses in the AM equipment and services industry.
‘Additive manufacturing is a key part of GE’s evolution into a digital industrial company,’ said Jeff Immelt, chairman and CEO of GE. ‘We are creating a more productive world with our innovative world-class machines, materials and software. We are poised to not only benefit from this movement as a customer, but spearhead it as a leading supplier. Additive manufacturing will drive new levels of productivity for GE, our customers, including a wide array of additive manufacturing customers, and for the industrial world.’
Arcam AB, based in Mölndal, Sweden, invented the electron beam melting machine for metal-based additive manufacturing, and also produces advanced metal powders. Arcam generated $68 million in revenues in 2015 with approximately 285 employees.
SLM Solutions Group, based in Lübeck, Germany, produces laser machines for metal-based additive manufacturing with customers in the aerospace, energy, healthcare, and automotive industries. SLM generated $74 million in revenues in 2015 with 260 employees.
‘We chose these two companies for a reason,’ said Joyce. ‘We love the technologies and leadership of Arcam AB and SLM Solutions. They each bring two different, complementary additive technology modalities as individual anchors for a new GE additive equipment business to be plugged into GE’s resources and experience as leading practitioners of additive manufacturing. Over time, we plan to extend the line of additive manufacturing equipment and products.’
GE will maintain the headquarters locations and key operating locations of Arcam and SLM, as well as retain their management teams and employees. GE expects to grow the new additive business to US$1 billion by 2020 and also expects US$3-5 billion of product cost-out across the company over the next ten years.
This story is reprinted from material from GE, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Sandvik becomes research partner in heavy vehicle manufacturing
Hardmetal specialist Sandvik Coromant has joined a center researching powertrain manufacturing for heavy vehicles applications as a partner.
The center is part of the KTH Royal Institute of Technology, German research organization Fraunhofer and RISE (Research Institutes of Sweden). It was inaugurated at KTH in Stockholm, Sweden with the other two industrial partners – Volvo and Scania.
The center will primarily focus on improving the powertrain production process. This involves, for example, material selection and machining of camshafts and engines. Sandvik Coromant has been involved in selecting the focus areas and the initial projects, and is now taking part in three of the main projects, the company says.
This story is reprinted from material from Sandvik Coromant, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Million dollar investment in composite recycling
The Composite Recycling Technology Center (CRTC) in the US has been awarded a US$1.73 million state grant to fund composite recycling equipment at its new Port Angeles facility.
The grant by the Washington State Department of Commerce from its Clean Energy Fund 2 program, will allow the purchase and installation of equipment to recycle carbon fiber scrap from the aerospace industry into value-added products.
Production at the site should begin by the end of this year. The facility’s product offerings will focus long-term on clean-energy applications, with specific products yet to be announced.
‘This grant is one of the last pieces of the puzzle to enable CRTC to become the source of new jobs and economic development for our community and county,’ said Bob Larsen, CRTC CEO. ‘CRTC is now poised to accelerate its production plans and increase the number of jobs it creates in the coming year.’
CRTC is currently the only facility in the world to divert uncured carbon fiber composite scrap from landfills and transform it into consumer products. The material – lighter than aluminum and stronger than steel – is used to create lightweight airplane and automobile parts, but up to 30% of it ends up as manufacturing scrap. As it finds new uses for aerospace industry composite waste, the CRTC production process using recycled carbon fiber uses only 10% of the energy needed for like products made from virgin carbon fiber, the organization says.
CRTC has a supply agreement with Toray Composites America, and discussions are underway with other major carbon fiber scrap producers in Washington and in other parts of the country.
This story is reprinted from material from the CRTC, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
EconCore increases US distribution
Wabash National Corporation, a producer of semi-trailer and liquid transportation systems, has formed a new agreement with EconCore NV to distribute EconCore’s honeycomb core production technology in North America. Wabash National has the exclusive rights to manufacture and sell certain honeycomb sandwich material configurations in the containment and transportation industries in the United States, Canada and Mexico.
The honeycomb core technology is already used in numerous industries, including aerospace, automotive, marine, and wind and solar energy.
‘We’re exploring a number of applications where we can innovate and use this honeycomb core technology in existing products to significantly reduce weight, thus providing our customers a superior value proposition,’ said Brian Bauman, vice president and general manager of Wabash Composites. ‘In addition, this technology allows us to continue to focus on our growth and diversification efforts as we explore new end markets and products.’
This story is reprinted from material from EconCore, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
100,000 composite part
Orbital ATK and Airbus Americas report that they have completed the 100,000th composite part for the A350 XWB program.
‘As of the end of August, we have delivered 36 A350 XWB, with an additional 810 on order,’ said Geoffrey Pinner, senior vice president. ‘We are proud of the contributions from the highly skilled manufacturing facility in Utah and look forward to our continued partnership on the A350 XWB program.’
The 100,000 composite stringers and frames, the equivalent of more than 140 ship sets have been made using the company’s automated stiffener forming machines (ASFM) .
The A350 XWB work is performed at Orbital ATK’s 615,000 ft2 Aircraft Commercial Center of Excellence (ACCE) facility in Clearfield, Utah, USA.
This story is reprinted from material from Orbital, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Zenyatta Ventures Ltd scales up graphite testing
Zenyatta has reportedly scaled up testing of metal powder from its Albany graphite mine located in northern Ontario, Canada.
The first part of the metallurgical test work should produce larger market samples of high-purity graphite to test suitability for a range of applications by potential end-user partners, academic institutions and third party testing facilities. The company plans to produce around 50 kilograms of high-purity graphite material using the same caustic bake/leach method, employed previously to produce high-purity market samples. Test work on small market samples completed to date has reportedly confirmed the Albany graphite to have a good crystal structure (hexagonal) with a esirable purity and particle size for various applications such as lithium ion batteries, fuel cells, powder metallurgy and graphene production.
‘Production of high-purity graphite market samples is essential in order to create and develop relationships with end-users during the product qualification and testing process,’ said Aubrey Eveleigh, president and CEO. ‘This phase of the metallurgical program is currently in progress and is anticipated to be completed in the fall of 2016.’
The second part of the metallurgical test work will focus on improving flow sheet parameters and developing a pilot scale simulation of a commercial process designed for the pre-feasibility study.
This story is reprinted from material from Zenyatta, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Sumitomo to acquire Keystone PM
Sumitomo Electric Industries is to acquire Keystone Powdered Metal Company, a US manufacturer of powdered metal components.
The agreement will be entered into between Keystone, Sumitomo Electric USA Holdings Inc. (SEUHO), a US 100% subsidiary of Sumitomo Electricm and a special purpose corporation to be established by SEUHO. SEUHO will acquire 100% stock of Keystone through the merger between Keystone (merging company) and the special purpose corporation. The acquisition is scheduled to be completed by the end of September.
The powdered metal components business of the Sumitomo Electric Group has expanded globally from its beginnings as Sumitomo Electric Sintered Alloy Ltd and supplies a variety of products primarily to Japanese manufacturers of cars, air conditioners, and automotive components. ‘This acquisition will enable us to expand sales networks for US car manufacturers as well as auto-parts manufacturers, enhance our presence in the US, and capture further business opportunities,’ the company said in a press release.
This story is reprinted from material from Sumitomo, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
3D printing makes bone scaffolds a better fit
Serious injury or damage to the face and head can require bone grafts. But 3D printing is emerging as an option to tailor artificial bone scaffolds to fit the patient’s needs exactly. And if those scaffolds can be made from biodegradable metals, patients can avoid removal surgeries at a later stage.
Now researchers from the University of Pittsburgh, Robert Morris University, Ort Braude College in Israel, and ExOne Company think they have come up with the ideal mix of metals to create an alloy that will degrade without eliciting a toxic response [Hong et al., Acta Biomaterialia (2016), doi: 10.1016/j.actbio.2016.08.032].
“Mg is by far the most popular and attractive metal of choice as a biodegradable or bioabsorbable system since it has properties very similar to bone,” explains Prashant N. Kumta of the University of Pittsburgh. “The only limitation is that it degrades very rapidly.”
To overcome this problem, researchers have investigated other metals like Fe, which degrades very slowly. A combination, however, of Mg and Ca alloyed with Fe-Mn could offer a solution.
The team created Fe-Mn-Mg/Ca alloys using a process known as high energy mechanical milling (HEMM) or high energy mechanical alloying (HEMA) in which powders of each element are pulverized together by stainless steel balls in a mill. A scaffold of any shape can then be built up layer-by-layer via a 3D printing process called binder-jetting where a liquid binder is ejected through a nozzle, holding the alloy powder together. A curing step after the structure is created removes the binder, while subsequent heating joins the alloy powder particles together.
“The Fe-Mn-Mg/Ca alloys are unique and [this] is the first demonstration that introducing Mg and Ca can accelerate corrosion,” says Kumta. “The alloy is also cytocompatible without eliciting any toxic response.”
While the results demonstrate that the Fe-Mn-Mg/Ca alloys can be easily 3D printed using the binder jetting approach, other additive manufacturing methods should work just as well, say the researchers.
The resulting alloys have just the right combination of strength, ductility, and controlled, rapid corrosion for use as degradable bone scaffolds.
“These alloys could be more acceptable than Mg-based alloys, which exhibit rapid corrosion leading to hydrogen pockets that can cause toxicity of the local tissue,” explains Kumta.
The only problem is that the alloy particles produced by milling tend to vary in size and shape. This can produce structures that are quite porous – which is good from the corrosion point of view but less advantageous in terms of strength. The researchers believe that atomization and quenching strategies, which would produce more spherical alloy particles, could overcome this shortcoming.
Doped up mesoporous supercapacitor
A nitrogen-doped mesoporous carbon thin film acts as a high capacity, binder-free supercapacitor with a long cycling stability, according to research published in the journal Applied Materials Today. [P Hu et al., Appl. Mater. Today (2016) 5, 1-8; DOI: 10.1016/j.apmt.2016.08.001]
Pan Hu and Xinsheng Peng of Zhejiang University, in Hangzhou and Donghui Meng, Guohua Ren, Rongxin Yan of Beijing Institute of Spacecraft Environment Engineering, China, explain how they could convert gelatin/copper hydroxide nanostrands into a composite film of gelatin/HKUST-1, which they could then carbonize to generate the free-standing composite films. These films have a high specific energy of 28.1 Watt hours per kilogram and a specific capacity of 316 Farads per gram at a current density of 0.5 Amps per gram. They also have a capacitance retention of almost 93% and degrade by a mere 0.00064% after 11000 charge-discharge cycles, the team reports.
Porous carbons, with their high surface area to volume ratio have been the focus of much research for their potential applications in electronics, separation science and beyond. They can be generated by chemical vapour decomposition, laser ablation, chemical or physical activation, carbonization of polymer aerogels, carbide-derived carbon, as well as template procedures. Often, their production then requires an additional step to dope them with nitrogen. Simpler approaches to functional porous carbons, for development as electrodes or supercapacitors are keenly sought and as such Hu and colleagues have sidestepped the problem of low doping levels seen with earlier approaches. Instead of using post-treatment with ammonia gas, the team has demonstrated how starting with a nitrogen-rich carbon compound and the carbonizing the processed material gives them much higher nitrogen content and so potentially more powerful electrical phenomena in the resulting doped material.
They previously suggested gelatin as a low-cost, abundant fibrous material having a high nitrogen content, by virtue of it being a protein, as a precursor for a doped mesoporous carbon. Early studies required harsh conditions to generate the mesoporous material, but this leads to powders that then require a non-electrochemical binder to hold the particles together in a solid block before use. The presence of the binder inhibits activity, so a binder-free approach would be better. The team's room temperature method generates active thin films rather than powders and so requires no binder to aggregate particles into a usable component for their supercapacitor.
The team concedes that their thin films are no more electrochemically active than other carbon-based materials, it is their method that sets apart the products and opens the door to a cool and efficient fabrication of supercapacitor films.
David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".
Introducing Materials Today Chemistry and Materials Today Energy
Materials Today is delighted to announce the launch of two new journals: Materials Today Chemistry and Materials Today Energy. These journals represent the latest addition to Elsevier’s Materials Today family; a growing collection of daughter titles, and an extended family of over 100 publications in materials sciences and related fields.
Now open for submissions, Materials Today Chemistry and Materials Today Energy are multi-disciplinary journals focused on two of the largest and most exciting areas of materials science, and will publish high quality original research articles, short communications and reviews. The journals offer rapid review with expert advice, and maximum visibility of published articles via ScienceDirect and MaterialsToday.com.
Leading the new energy focused title is Editor-in-Chief Professor Chun-Sing Lee from the City University of Hong Kong. "Our quality of living is closely related to how we can harvest, convert and store energy in an efficient, safe and clean manner. Although great progress in energy-related technologies has been achieved, more work is urgently needed; all of these technologies are closely related to the development of new materials” commented Prof Lee. “With extensive and increasing international research on advanced materials for energy applications, the editorial team expects to see high demand and rapid growth of Materials Today Energy over the next few years.”
Meanwhile, Professor Xian-Zheng Zhang from Wuhan University China is at the helm of Materials Today Chemistry, as the Editor-in-Chief. Materials chemistry is one of the fastest developing areas of science, covering the application of chemistry-based techniques to the study of materials. Prof Zhang described his excitement at being involved in the new title; “I am delighted to be leading one of the two newest Materials Today journals. Materials Today Chemistry will provide researchers with a new forum for the discussion of ground breaking results in materials chemistry and related disciplines, and is expected to become one of the leading publications in the field."
Alongside the extended family of journals, the new publications join Applied Materials Today, as well as the flagship Materials Today title, which is also undergoing some exciting changes - in addition to the dedicated proceedings journal Materials Today: Proceedings, and sound science publication Materials Today Communications.
For more information on the Materials Today family visit www.materialstoday.com/about.
Standards required for commercial spaceflight
ASTM International plans to create a new technical committee for developing voluntary consensus standards for commercial spaceflight.
This comes in part as a result of the updated US Commercial Space Launch Competitiveness Act of 2015 (SPACE Act). The US Federal Aviation Administration’s Commercial Space Transportation Advisory Committee (COMSTAC) Standards Working Group is recommending the organization of the new group.
‘Consensus standards from organizations like ASTM International are known to enhance safety and efficiency in aerospace,’ the organization said in a press release. ‘New standards could support the growing number of people and entities who design, manufacture, and operate commercial space vehicles for both human and unmanned flights.'
The organization will be discussing the creation of a committee at a meeting on 24 October at the FAA Office of Commercial Space Transportation (AST) RTCA Inc in Washington, DC, USA. Industry stakeholders and others interested in charting a path towards standardization for commercial spaceflight are welcome to attend.
The objectives of the meeting would be to bring an array of industry experts together, identify specific standards needs, determine if ASTM International should formally launch a new activity; and, if so, develop and approve title, scope, and structure of a new technical committee.
This story is reprinted from material from ASTM, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Erasteel achieves EN9100 certification
Metallied, a facility for making metal powders for additive manufacturing (AM) for Erasteel and Aubert & Duval, based in Irun, Spain, has received EN9100 accreditation.
‘This achievement confirms the company's commitment to quality in the aerospace industry which has been a core business of Aubert & Duval, a sister company of Erasteel for many years,’ the company said in a press release. ‘The stringent requirements of this standard will also benefit customers of other markets.’
Erasteel develops and produces Pearl Micro metal powders used for additive manufacturing.
This story is reprinted from material from Erasteel, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Bodycote acquires Nitrex Metal Technologies
Bodycote has acquired Nitrex Metal Technologies, a specialist in gas nitriding and ferritic nitrocarburizing in both batch and continuous forms.
The addition of Nitrex Metal Technologies to the Bodycote Group will reportedly broaden the range of thermal processing services that Bodycote offers, which range from atmosphere heat treatments like batch IQ, vacuum, and induction to technologies such as LPC, BoroCote, and Corr-I-Dur.
‘Nitrex Metal Technologies is a great addition to the Bodycote Group,’ said Dan McCurdy, president of Bodycote Automotive and General Industrial Heat Treating in North America and Asia. ‘Along with the rest of Bodycote’s existing service offerings, this acquisition really cements our position as the go-to expert source for all things nitriding.’
This story is reprinted from material from Bodycote, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Research into AM metal powder degradation
LPW Technology, a manufacturer of metal powder for additive manufacturing (AM), has built a new R&D facility within the Daresbury Laboratory in Cheshire, UK.
The new facility will be used to develop LPW’s products to address the issues of metal powder degradation and contamination during the AM process. The facility, which houses a number of metal printers, will be led by LPW’s technical director, Andy Florentine.
‘In addition to expanding our powder manufacturing capabilities, we see the future of metal AM in solving the problems associated with how the powder is reused within the AM machine,’ said Dr Phil Carroll, MD and founder of the business. ‘We call the solution PowderLife – a metal powder lifecycle management system that strictly controls risk and traceability for AM metal part manufacturers. It is an integrated suite of software, hardware, analysis, applications support and, of course, metal powders.’
Daresbury Laboratory is a UK government facility dedicated to scientific research in fields such as accelerator science, bio-medicine, physics, chemistry, materials, engineering and computational science.
This story is reprinted from material from LPW, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.