Researchers ‘watch’ crystal structure change in real time
Washington State University researchers have met the long-standing scientific challenge of watching a material change its crystal structure in real time.
While exposing a sample of silicon to intense pressure – due to the impact of a nearly 12,000 mph plastic projectile – they documented the transformation from its common cubic diamond structure to a simple hexagonal structure. At one point, they could see both structures as the shock wave traveled through the sample in less than half a millionth of a second.
Their discovery is a dramatic proof of concept for a new way of discerning the makeups of various materials, from impacted meteors to body armor to iron in the center of the Earth.
Until now, researchers have had to rely on computer simulations to follow the atomic-level changes of a structural transformation under pressure, said Yogendra Gupta, Regents professor and director of the WSU Institute of Shock Physics. The new method provides a way to actually measure the physical changes and to see if the simulations are valid.
“For the first time, we can determine the structure,” Gupta said. “We’ve been assuming some things but we had never measured it.”
Writing in Physical Review Letters, one of the leading physics journals, the researchers say their findings already suggest that several long-standing assumptions about the pathways of silicon’s transformation “need to be re-examined.”
The discovery was made possible by a new facility, the Dynamic Compression Sector at the Advanced Photon Source located at the Argonne National Laboratory. Designed and developed by WSU, the sector is sponsored by the U.S. Department of Energy’s National Nuclear Security Administration, whose national security research mission includes fundamental dynamic compression science.
The Advanced Photon Source synchrotron, funded by the Department of Energy’s Office of Science, provided high-brilliance x-ray beams that pass through the test material and create diffraction patterns that the researchers use to decode a crystal changing its structure in as little as 5 billionths of a second.
“We’re making movies,” said Gupta. “We’re watching them in real time. We’re making nanosecond movies.”
Stefan Turneaure, lead author of the Physical Review Letters paper and a senior scientist at the WSU Institute for Shock Physics, said the researchers exposed silicon to 19 gigapascals, nearly 200,000 times atmospheric pressure. They accomplished this by firing a half-inch plastic projectile into a thin piece of silicon on a Lexan backing. While x-rays hit the sample in pulses, a detector captured images of the diffracted rays every 153.4 nanoseconds – the equivalent of a camera shutter speed of a few millionths of a second.
“People haven’t used x-rays like this before,” said Turneaure. “Getting these multiple snapshots in a single impact experiment is new.”
“What I’m very excited about is we are showing how the crystal lattice, how this diamond structure that silicon starts out with, is related to this ending structure, this hexagonal structure,” said Gupta. “We can see which crystal direction becomes which crystal direction. Stefan has done a great job. He has mastered that. We were able to show how the two structures are linked in real time.”
New nontoxic process promises larger ultrathin sheets of 2-D nanomaterials
A team of scientists led by the Department of Energy's Oak Ridge National Laboratory has developed a novel way to produce two-dimensional nanosheets by separating bulk materials with nontoxic liquid nitrogen. The environmentally friendly process generates a 20-fold increase in surface area per sheet, which could expand the nanomaterials' commercial applications.
"It's actually a very simple procedure," said ORNL chemist Huiyuan Zhu, who co-authored a study published in Angewandte Chemie International Edition. "We heated commercially available boron nitride in a furnace to 800 degrees Celsius to expand the material's 2D layers. Then, we immediately dipped the material into liquid nitrogen, which penetrates through the interlayers, gasifies into nitrogen, and exfoliates, or separates, the material into ultrathin layers."
Nanosheets of boron nitride could be used in separation and catalysis, such as transforming carbon monoxide to carbon dioxide in gasoline-powered engines. They also may act as an absorbent to mop up hazardous waste. Zhu said the team's controlled gas exfoliation process could be used to synthesize other 2D nanomaterials such as graphene, which has potential applications in semiconductors, photovoltaics, electrodes and water purification.
Because of the versatility and commercial potential of one-atom-thick 2D nanomaterials, scientists are seeking more efficient ways to produce larger sheets. Current exfoliation procedures use harsh chemicals that produce hazardous byproducts and reduce the amount of surface area per nanosheet, Zhu said.
"In this particular case, the surface area of the boron nitride nanosheets is 278 square meters per gram, and the commercially available boron nitride material has a surface area of only 10 square meters per gram," Zhu said. "With 20 times more surface area, boron nitride can be used as a great support for catalysis."
Further research is planned to expand the surface area of boron nitride nanosheets and also test their feasibility in cleaning up engine exhaust and improving the efficiency of hydrogen fuel cells.
Chemical etching method helps transistors stand tall
Smaller and faster has been the trend for electronic devices since the inception of the computer chip, but flat transistors have gotten about as small as physically possible. For researchers pushing for even faster speeds and higher performance, the only way to go is up.
University of Illinois researchers have developed a way to etch very tall, narrow finFETs, a type of transistor that forms a tall semiconductor “fin” for the current to travel over. The etching technique addresses many problems in trying to create 3-D devices, typically done now by stacking layers or carving out structures from a thicker semiconductor wafer.
“We are exploring the electronic device roadmap beyond silicon,” said Xiuling Li, a U. of I. professor of electrical and computer engineering and the leader of the study. “With this technology, we are pushing the limit of the vertical space, so we can put more transistors on a chip and get faster speeds. We are making the structures very tall and smooth, with aspect ratios that are impossible for other existing methods to reach, and using a material with better performance than silicon.”
The team published the results in the journal Electron Device Letters.
An array fin transistors made by the MacEtch method. The fins are tall and thin, with a higher aspect ratio and smoother sides than other methods can produce.
Typically, finFETs are made by bombarding a semiconductor wafer with beams of high-energy ions. This technique has a number of challenges, Li said. For one, the sides of the fins are sloped instead of straight up and down, making them look more like tiny mountain ranges than fins. This shape means that only the tops of the fins can perform reliably. But an even bigger problem for high-performance applications is how the ion beam damages the surface of the semiconductor, which can lead to current leakage.
The Illinois technique, called metal-assisted chemical etching or MacEtch, is a liquid-based method, which is simpler and lower-cost than using ion beams, Li said. A metal template is applied to the surface, then a chemical bath etches away the areas around the template, leaving the sides of the fins vertical and smooth.
“We use a MacEtch technique that gives a much higher aspect ratio, and the sidewalls are nearly 90 degrees, so we can use the whole volume as the conducting channel,” said graduate student Yi Song, the first author of the paper. “One very tall fin channel can achieve the same conduction as several short fin channels, so we save a lot of area by improving the aspect ratio.”
The smoothness of the sides is important, since the semiconductor fins must be overlaid with insulators and metals that touch the tiny wires that interconnect the transistors on a chip. To have consistently high performance, the interface between the semiconductor and the insulator needs to be smooth and even, Song said.
Right now, the researchers use the compound semiconductor indium phosphide with gold as the metal template. However, they are working to develop a MacEtch method that does not use gold, which is incompatible with silicon.
“Compound semiconductors are the future beyond silicon, but silicon is still the industry standard. So it is important to make it compatible with silicon and existing manufacturing processes,” Li said.
The researchers said the MacEtch technique could apply to many types of devices or applications that use 3-D semiconductor structures, such as computing memory, batteries, solar cells and LEDs.
Process could make key biodegradable polymer stronger and longer-lasting
Polylactic acid, or PLA, is a biodegradable polymer commonly used to make a variety of products from disposable cups to medical implants to drug delivery systems. A team of Brown University researchers has shown that by treating PLA at various temperatures and pressures, they can induce a new polymer phase in the material — one that could possibly decrease the rate at which it degrades.
“It’s an exciting finding from the standpoint of basic science, in that we’ve found a new polymer phase and have identified a method for inducing it,” said Edith Mathiowitz, a professor of medical science and engineering at Brown. “In terms of applications, the polymer we worked with in this study has many uses, and we believe the properties we have discovered now will allow us to make it better.”
The findings are published in the journal Polymer.
PLA is a semi-crystalline material, meaning parts of the material’s molecular structure are ordered into crystals while the rest is disordered, or amorphous, like glass. Work by previous researchers had shown that treating PLA with heat could increase the material’s crystalline makeup, which could help to increase its strength. Researchers in Mathiowitz’s lab, led by doctoral candidate and U.S. Navy veteran Christopher Baker, wanted to see if adding pressure to the treatment process would further influence the material’s structure.
Baker treated PLA samples under a variety of different temperature and pressure conditions for varying amounts of time. Pressures ranged from 2,000 to 20,000 pounds per square inch. Temperatures used for treatments were above, below and nearly equal to the glass transition temperature for PLA — the temperature at which the amorphous parts of the material transition from solid to rubbery.
Baker showed that the treatments increased the amount of crystalline area in the material, but there was another more surprising finding. At higher temperatures and pressures, the amorphous parts of the material became birefringent, meaning that they bend light differently depending upon how the light is polarized. That is an indicator of a substantial structural change in the amorphous portions of the material.
Generally speaking, birefringence is a property found in crystalline materials, so seeing it in the amorphous regions of PLA was a surprise. “We didn’t expect it to have such properties,” Mathiowitz said. “So to see it in the amorphous phase was really amazing.”
Baker then used several methods to further characterize how the amorphous regions had changed. Using a technique called X-ray diffraction, he showed that polymer strands in some of the amorphous sections had become dramatically more ordered.
“The polymer strands are normally a tangled mess,” Baker said. “But we found when we processed the material that the amorphous region became less entangled and much more oriented in a particular direction.”
Further thermal analysis showed that the more ordered sections had a higher glass transition temperature. In general, amorphous materials with higher glass transition temperatures degrade at significantly slower rates.
The new amorphous phase combined with the overall increase in crystallinity in the treated samples could have significant implications for the material’s mechanical properties, the researchers said. The higher crystallinity could make it stronger, while the more ordered amorphous sections could make it last longer. That slower rate of degradation could be particularly useful in medical applications, an area in which Mathiowitz’s lab specializes.
For example, PLA is used as a coating for time-release pills and implantable drug delivery systems. If the rate at which PLA degrades can be controlled, the rate at which it delivers a drug can be altered. There is also interest in using PLA for plates and screws used to stabilize broken bones. The advantage to PLA implants is that they degrade over time, so a patient would not need a second surgery to remove them. PLA may degrade too quickly for some of these applications, but if this new polymer phase slows degradation, it may become a better option.
“Now that we’ve shown that we can intentionally induce this phase, we think it could be very useful in many different ways,” Mathiowitz said.
The researchers plan more research aimed at quantifying changes in material properties as well as investigating whether this phase can be induced in other semi-crystalline materials.
EVAPORATION INSIGHTS LEARNING CENTER
Genevac announces the launch of a new website that provides easily navigable access to the company’s comprehensive portfolio of evaporators and concentrators to suit almost any solvent removal application, purchasing budget or productivity requirement. Located at www.spscientific.com/genevac - the new site offers visitors ready access to an extensive searchable library of articles, technical papers, application notes and videos in the Evaporation Insights Learning Centre. Alison Wake, Genevac Product & Marketing Manager commented: “We have adopted the learning centre concept developed by our parent company SP Scientific who have found this information rich resource to be the most popular feature for both customers and visitors to the web site. There are many applications for Genevac evaporators and concentrators ranging from environmental analysis through natural products research to parallel chemistry. Our newEvaporator Insights Learning Centre provides scientists with access to the largest single evaporator / concentrator knowledge base on the internet”. In addition the website offers detailed Genevac product information (key feature/benefits, specifications, application examples, accessories and literature), information about service and support around the world and news of the latest events the company is participating in. The new site brings Genevac together with other SP Scientific brands onto one website. SP Scientific is the synergistic collection of well-known, well-established and highly regarded scientific equipment brands including Genevac, VirTis, FTS Systems, Hotpack, Hull, and most recently PennTech, joined to create one of the leading manufacturers of specialty equipment for pharmaceutical, academia, biotechnology and industry.
EVAPORATION INSIGHTS LEARNING CENTER
The EZ-2 Elite centrifugal evaporator from Genevac, an evaporator of choice for large Pharma R&D, uniquely combines high performance, versatility, ease-of-use and affordability making it the perfect workhorse system for Contract Research Organisations (CRO's). The EZ-2 Elite is designed to efficiently concentrate or completely dry samples. It is compatible with a wide selection of sample holders, enabling evaporation from common sample container formats including round-bottom flasks, tubes vials and microplates. SampleGenie™ technology combined with a FastLyo programme on the EZ-2 Elite allows HPLC fractions to be concentrated and freeze dried directly into a submission vial. This innovation produces a weighable solid, eliminating manual handling, increasing recoveries and removing the chance of cross-contamination. Operating the EZ-2 Elite is highly intuitive: just load your samples, select maximum safe temperature for samples, select solvent type and hit start. Offering unattended operation through a suite of pre-programmed methods, the compact evaporator requires no user training, even a beginner can competently use the system within 5 minutes. Drawing upon Genevac's technological leadership in high performance evaporation, the EZ-2 Elite is able to routinely dry stubborn samples. Benefiting from a high-performance scroll pump that delivers deep vacuum, the product is able to remove even high-boiling solvents such as DMSO and NMP and acidic solvents such as HCl. Internal heating of vapour duct and system components ensures that such challenging solvents only collect in the SpeedTrap™ condenser and not anywhere else. The condenser comes with automatic defrost and drain technology. The evaporator controls the condenser and the solvent collection vessel, offering mid-method defrosting and draining.
SHOWA DENKO (SDK) (TOKYO: 4004) HAS DECIDED TO EXPAND ITS PRODUCTION CAPACITY
The range of LIB’s use is rapidly increasing. These days, more and more LIBs are used not only in small devices such as smartphones and tablets but also in large equipment, especially in electric vehicles (EVs). In China, the demand for large LIBs for use in EVs and electric buses has been significantly increasing in recent years due to stricter emission control and subsidies to EVs by governments and a surge in public awareness of the environment. LIBs for use in EVs have large capacities, thereby requiring a lot of materials. As EV spreads, the size of the market for LIB materials is expected to continue expanding, and will be about ¥ 2 trillion in 2020. SCMGTM has advantages of low resistance and long life, and demonstrates high performance when used in LIBs for EVs. SCMGTM is also rated high by car manufacturers as material to be used in LIBs for vehicles with idling-stop function, which is expected to spread further. This time, SDK decided to expand its capacity for producing SCMGTM in order to respond to a lively demand from our customers. Commercial operation of the expanded production facility is scheduled to start at the end of 2016. Through this capacity expansion, Omachi Plant’s SCMGTM production capacity will be increased by 50%, to 1,500t per year. In addition, SDK started to outsource a part of its SCMGTM production to a manufacturer in China in this June. In January 2016, SDK also started to outsource a part of its production of SDXTM carbon-coated aluminum foil, which is used as collector for cathode in LIB, to a Chinese manufacturer. SDXTM has the advantages of low resistance and close adhesion to cathode materials in LIBs, thereby improving charge/discharge performance of LIBs and contributing to a reduction in the amount of conduction supportive agents and binders added to cathode materials in LIBs. The demand for SDXTM has also been increasing especially in the field of LIBs for EVs. To meet this increase in demand, it became necessary for SDK to expand its SDXTM production capacity. Thus SDK started to produce SDXTM in China.
UMICORE OPENS CATALYST FACILITY IN POLAND
Supporting Europe’s aim “Cleaner air for all”
The materials technology and recycling group Umicore today officially opened its new production plant for emission control catalysts in Nowa Ruda, Poland (near Wroclaw). The facility allows the company to meet the growing demand for automotive catalysts from its customers in Europe, a trend that is supported by tightening emission legislation in the European Union. With this addition to its European footprint, Umicore complements its existing automotive catalysts production facilities in Germany, France and Sweden. The plant, which is located in the special economic zone of Walbrzych, employs around 80 people and works with the newest generation of process technologies. Pascal Reymondet, Executive Vice President Catalysis at Umicore, comments: “This investment enables us to supply our customers with technologies to meet the most stringent emission legislation and support Europe’s aim for ‘cleaner air for all’. It also underscores our ambition to be a clear leader in materials for clean mobility”. Umicore’s catalysts enable improvements to air quality by transforming harmful vehicle emissions through sophisticated catalytic processes. Umicore has been researching in the automotive catalysts sector for over half a century and producing them for over 40 years. Since then its technology has prevented hundreds of million tonnes of harmful pollutants from being emitted into the air.
SUNCOAST HEALTH BRANDS RELEASES TWO NEW BRAIN HEALTH SUPPLEMENTS WITH COGNIZIN® CITICOLINE
Suncoast Health Brands has leveraged the power of Cognizin® Citicoline for two new brain-health supplements designed to promote healthier brain activity.
Cerebral Clarity and Focus are two of four supplements offered by Suncoast Health Brands to fuel the brain. Both use Cognizin® as the foundational ingredient for blends that may help the body combat stress and mental fatigue while improving memory performance, attention, alertness and antioxidant levels. “When we created our brain support line for Suncoast Health supplements, we wanted to use the best ingredients, which is why we decided to put our best foot forward, do the research and find the best ingredients on the planet for our Cerebral Clarity and Focus products,” said Clay Desjardine, Suncoast Health Brand CEO. “We have created products we can hang our hats on and truly be proud to say are in our line. We know everyone is going to love them once they use them. One of those key ingredients we sourced is Cognizin®. We stand behind the quality and reliability of Cognizin®”. Citicoline is a compound that promotes the production of phosphatidylcholine (phospholipids), important for brain function. Phospholipids make up approximately 30% of brain tissue, aid neural communication and provide essential protection for neurons. Clinical research has shown that citicoline has multiple applications and is able to improve various aspects of the brain’s physiological activity. Cognizin® Citicoline is a branded form of citicoline, an essential substance for brain health. Citicoline works to enhance communication between neurons, maintain normal levels of acetylcholine, protect neural structures, and enhance health brain activity and energy.