Officials at the University of Dayton announced that the school has created a new research center focused on various thin-film investigations and applications. The initiative, dubbed the Center of Excellence in Thin-Film Research and Surface Engineering (CETRASE), hopes to deliver significant breakthroughs in everything from fuel and solar cell to optics, sensors, and electronics.
In a UD press release, Guru Subramanyam says, ”We want to find ways to make better, more efficient, cost-effective sensors, electronics, electro-optics, and energy systems and hopefully create new jobs in the region.”
Subramanyam, who is currently serving as leader of CETRASE, is chair of UD’s electrical and computer engineering department, and is one of several CETRASE faculty “team” members. The school says team members come also come for UD’s departments of materials engineering, biology, and physics as well as the electro-optics graduate program and the University of Dayton Research Institute.
Subramanyam says CETRASE provides the opportunity to move from ad hoc collaborations to strategic efforts and the pursuit of funding. “It makes sense for us to put our heads together for a center where we can coordinate activities, interact and share common equipment and costs. We also will have strength in numbers when submitting proposals as part of a center,” he says in the release.
In an interview, Subramanyam says before CETRASE was formed, “We had our own separate projects, funding applications and supporters. One or two of us would collaborate if we discovered an overlap, but as a group we didn’t come together until now. Now, for the first time, we will be developing joint priorities and funding proposals. Focusing on joint activities will be a change for us, but as a united group, I think we will be more attractive to funding agencies.”
“In addition,” Subramanyam continues, ”we will be holding regular CETRASE events, such as monthly seminars and bringing in invited guest speakers.”
Subramanyam notes that CETRASE has already hired its first dedicated staff member, a PhD who will serve as a coordinator of the center’s activities.
When I asked Subramanyam if CETRASE has any projects that might be of particular interest to the ceramics community, he says, “We have quite a bit of ceramic-related work going on, such as barium strontium titanate thin films for tunable dielectrics, yttrium barium copper oxide thin films and vanadium oxide research for the Air Force.”
He says that one immediate benefit is that CETRASE participants have access to team members’ advanced laser sources, pulse laser deposition systems, SEMs, TEMs, X-ray diffraction and Raman spectroscopy equipment, magnetron sputtering systems, and photolithography tools.
University spokesperson Shawn Robinson tells me UD’s materials engineering research currently ranks second in the nation based on research dollars.
Micrograph of one strand of a new spray-on super-nanotube composite developed by the National Institute of Standards and Technology (NIST) and Kansas State University. A ceramic shell surrounds the multiwall nanotube core. The composite is a promising coating for laser power detectors. (Color added for clarity.) Credit: Kansas State University.
How does one measure the optical power output of lasers that are able to—and even designed to—destroy materials? Some lasers with optical output that high are built to be weapons; others are used for friendlier purposes like defusing unexploded landmines.
Designing a power detector that can capture and measure very high laser power without vaporizing away is one application of a new coating developed by researchers at Kansas State University and NIST. The team, led by Gurpreet Singh at KSU published results on a new carbon nanotube-ceramic composite coating in ACS Applied Materials and Interfaces, in their recent article, “Very high laser-damage threshold of polymer-derived Si(B)CN-carbon nanotube composite coatings.”
According to a NIST press release, NIST has been coating optical detectors with carbon nanotubes because their intense black color maximizes light absorption. This new coating comprises multiwall carbon nanotubes (MWCNT) encased in an amorphous SiBCN shell, as shown in the image above. Adding boron increases the refractoriness of the coating.
The KSU team developed the composite with an assist from the NIST researchers who suggested using toluene for both the preceramic polymer solvent and for the MWCNT dispersant. Singh explained in an email, “Toluene-CNT dispersions were more stable and homogeneous [than dispersions based on] chloroform, acetone, or water.” The NWCNTs are dispersed in toluene into which preceramic polymer is added. When the solution is heated to 1,100°C, an amorphous SiBCN shell forms over the MWCNTs. The composite is ground into a fine powder, dispersed in toluene, and sprayed onto copper substrates.
The optical power meter works by absorbing the high-intensity laser light on its inside surface, which is typically a copper cone calorimeter coated with a black absorbing material (for example, the new MWCNT-ceramic coating). It absorbs the incident light and converts it to heat. The heat transfers to water flowing behind the copper heat sink. By precisely measuring the water flow and temperature increase, the energy absorbed can be calculated. (See schematic of device.)
To test the efficacy of the composite coating, the team subjected it to 10.6-micrometer wavelength irradiation from a 2.5 kW CO2 laser. The composite coating outperformed other tested materials-MWCNT, single wall CNT, and carbon paint- by an order of magnitude or more. According to the paper’s abstract, the damage threshold for the composite coating was 15 kWcm-2 with an optical absorbance of 97 percent. Essentially, the coating absorbed all of the light.
In contrast, the MWCNT-only coating exhibited damage at 1.4 kWcm-2 with 76 percent absorbance. SWCNT broke down at 0.8 kWcm-2 and only 65 percent absorbance, and damage started in the carbon paint coating at 0.1 kWcm-2 and 87 percent absorbance.
According to the press release, the MWCNT component absorbs the irradiation and transmits the heat, while the ceramic shell provides oxidation and damage resistance. Apparently, though, under the right conditions, the outer shell oxidizes partially to form an external silica layer, which can be used to tune the coating depending on the application.
Singh said there are other possible applications for the MWCNT-ceramic coating, such as lithium-ion cycling. They are also looking into applications such as nanostructured coatings for protection in extreme environments like rocket nozzles.
This last application reminded me of an interview I did several years ago with NASA Space Shuttle astronaut, Danny Olivas. Olivas is a metallurgist and was very involved in the materials aspects of the failure analysis after Columbia disintegrated in 2003. In the aftermath, he also led the effort to develop an in-flight repair kit to mitigate damage to the heat shield tiles. (It was determined that a breach of the heat shield contributed to the Columbia tragedy.) The team developed a similar material: a preceramic polymer that fired to silicon carbide. The idea was that the polymer would be “painted” onto the damaged area and would fire, literally, using the reentry atmosphere itself as the “furnace.”
To the best of my knowledge, the system was never used (thankfully). The Shuttle program ended in 2011, so we will never know whether it would have worked.
There are currently over 40 million cars on Germany’s roads. Only a fraction of them are powered by electric energy—around 6,400 vehicles. The comparatively short range of electric cars doesn’t help their popularity. An extremely promising avenue of research is the lithium-sulfur battery, which is significantly more powerful and less expensive than the better-known lithium-ion battery. Although their short lifespan has made them unsuitable for use in cars before now, this may be about to change in the foreseeable future. Scientists at the Fraunhofer Institute for Material and Beam Technology IWS in Dresden have developed a new design that increases the charge cycles of lithium-sulfur batteries by a factor of seven. “During previous tests, the batteries scarcely crossed the 200-cycle mark. By means of a special combination of anode and cathode material, we have now managed to extend the lifespan of lithium-sulfur button cells to 1,400 cycles,” says Holger Althues, head of the Chemical Surface Technology group at IWS, who is delighted with his team’s breakthrough. The anode of the team’s prototype is not made from the usual metallic lithium, but from a silicon-carbon compound instead. This compound is significantly more stable, as it changes less during each charging process than metallic lithium. The more the structure of the anode changes, the more it interacts with the liquid electrolyte, which is situated between the anode and the cathode and carries the lithium-ions.
Once they’ve finished powering electric vehicles for hundreds of thousands of miles, it may not be the end of the road for automotive batteries, which researchers believe can provide continued benefits for consumers, automakers and the environment. Five used Chevrolet Volt batteries are at the heart of the Department of Energy Oak Ridge National Laboratory’s effort to determine the feasibility of a community energy storage system that would put electricity onto the grid. Over the next year, researchers from ORNL, General Motors and the ABB Group will conduct studies and compile data using a first-of-its-kind test platform officially commissioned today. ”With about one million lithium-ion batteries per year coming available from various automakers for the secondary market beginning in 2020, we see vast potential to supplement power for homes and businesses,” said Imre Gyuk, manager of the Energy Storage Research Program in DOE’s Office of Electricity Delivery and Energy Reliability. “Since these batteries could still have up to 80 percent of their capacity, they present a great opportunity for use in stationary storage devices before sending them to be recycled.”
Scientists are testing a new sensor designed to be the eyes of a future asteroid-tracking mission. “The Near Earth Object Camera (NEOCam) sensor will increase our ability to detect hazardous asteroids near the Earth and improve our understanding of threatening objects,” says William J. Forrest, professor of astronomy at the University of Rochester. Once launched, the space-based telescope would be positioned at a location about four times the distance between Earth and the moon. From this lofty perch, NEOCam could observe the comings and goings of objects near Earth without the impediments to efficient observing like cloud cover and even daylight. Asteroids do not emit visible light, they reflect it, which can make it difficult to determine size using visible light telescopes. But asteroids always emit infrared radiation. Asteroids emit most of their radiation at infrared wavelengths near about 10 microns (0.0004 inches), which humans perceive as heat. There is also relatively less radiation from stars and galaxies at these wavelengths, which simplifies detection of faint moving objects. “This sensor works at higher temperatures than any other similar ones we have at the moment,” says Judith Pipher, emeritus professor in physics and astronomy at Rochester. “This means they can be passively cooled, making the instrument less heavy and less expensive to put into space.”
(MIT Technology Review) The ability to slow down and trap light has become a hot topic in physics since it was first observed in the 1990s. The ability to trap electromagnetic waves has important applications in areas such as information storage, sensing and quantum optics. But the field has not progressed quite as quickly as many had hoped. That’s largely because of the complexity of the experimental setup and the difficulty in releasing the waves with their original properties after they have been trapped. Recently, Toshihiro Nakanishi and pals at Kyoto University in Japan reveal a new approach to this problem that has the potential to bring the routine storage and release of electromagnetic waves closer to reality. Conventional light trapping relies on atoms such as cesium and rubidium that have special combinations of ground and excited states. These atoms absorb at one specific frequency. However by zapping them with a laser at another frequency, called a probe, that excites the atoms, light can then pass through. This phenomenon is called electromagnetically induced transparency. But there is another way to achieve this kind of trapping, say Nakanishi and co. Instead of a cloud of atoms, these guys have created a metamaterial but does the same job. In this case, Nakanishi and company have created a metamaterial in which each repeating unit contains two variable capacitors. One of the capacitors is designed to absorb and radiate waves at a particular frequency while the other is designed to trap them. If the capacitors are tuned to the same frequency, any light at that frequency is absorbed and trapped. Detuning the capacitors then releases the electromagnetic waves, allowing them to continue on their way.
(American Physical Society) As a steel girder or concrete slab ages, its internal microstructure may change and lead to catastrophic failure. A proposed technique for analyzing the noise in ultrasound signals, described in Physical Review E, could provide an early warning system. The method is an adaption of an analysis previously used to characterize DNA. In the new computer simulations, the technique was able to correctly identify a wide range of microstructures in a one-dimensional material. The flooding of a river or a stock market crash may seem unpredictable, but often these events have some hidden relation to the past. The level of the river may be more likely to go up if it went up the week before, for example. It’s as if these systems retain some memory of past fluctuations, rather than having totally independent fluctuations from one moment to the next. One of the mathematical techniques for identifying such long-term memory in seemingly random data is called detrended fluctuation analysis (DFA). It has been used in the study of long-range correlations in DNA sequences, heart rates, human stride lengths, and temperature records. DFA could also be useful in ultrasonic evaluation of materials. Engineers currently use the scattering of ultrasound signals in a material as a way to nondestructively test for cracks or other large-scale features. However, research in 2004 showed that DFA performed on ultrasound signals from a cast-iron sample could reveal the fractal nature of the microstructure. André Vieira of University of São Paulo in Brazil and his colleagues at the Federal University of Ceará in Brazil have now developed a more general DFA framework for ultrasound inspection.
(R&D) Researchers are developing a new type of semiconductor technology for future computers and electronics based on “2D nanocrystals” layered in sheets less than a nanometer thick that could replace today’s transistors. The layered structure is made of a material called molybdenum disulfide, which belongs to a new class of semiconductors—metal di-chalogenides—emerging as potential candidates to replace today’s technology, complementary metal oxide semiconductors, or CMOS. New technologies will be needed to allow the semiconductor industry to continue advances in computer performance driven by the ability to create ever-smaller transistors. It is becoming increasingly difficult, however, to continue shrinking electronic devices made of conventional silicon-based semiconductors. “We are going to reach the fundamental limits of silicon-based CMOS technology very soon, and that means novel materials must be found in order to continue scaling,” says Saptarshi Das, who has completed a doctoral degree, working with Joerg Appenzeller, a professor of electrical and computer engineering and scientific director of nanoelectronics at Purdue’s Birck Nanotechnology Center. “I don’t think silicon can be replaced by a single material, but probably different materials will co-exist in a hybrid technology.” Findings show that the material performs best when formed into sheets of about 15 layers with a total thickness of 8 to 12 nanometers. The researchers also have developed a model to explain these experimental observations. “Our model is generic and, therefore, is believed to be applicable to any 2D layered system,” Das says. Molybdenum disulfide is promising in part because it possesses a bandgap, a trait that is needed to switch on and off, which is critical for digital transistors to store information in binary code.
David Willetts’ speech on the eight-part strategic technology roadmap for the UK. Credit EPSRC.
The United Kingdom’s Engineering and Physical Sciences Research Council (EPSRC) announced that seeks proposals to fund with a total of £85 million (approximately $120 million) aimed at increasing the nation’s research base related to three technologies:
- Advanced Materials (£30 million)
- Grid-scale Energy Storage (£30 million)
- Robotics & Autonomous Systems (£25 million)
An advocate for the funding has been David Willetts, the UK’s minister for universities and science. A report and speech (above) by Willetts in January of this year called for research in “eight great technologies.” Three of the eight are included in this funding announcement. Willetts says in a news release, “This £85 million capital fund will boost our research capability in advanced materials, energy storage, and robotics and autonomous systems. It will keep the UK at the forefront of science and innovation.”
David Delpy, the EPSRC’s chief executive, also notes in the release, “The work will help develop new ways of storing power, new materials that can aid manufacturing and other industries, and further developing how autonomous systems communicate, learn and work with humans.”
The EPSRC is somewhat analogous to the United States’ National Science Foundation and is the UK’s main agency for funding research in engineering and the physical sciences. It has a budget of around £800 million per year that it invests in research and postgraduate training.
In a detailed call for proposals (pdf), the EPSRC warns that it is not interested in creating new centers and will not accept proposals unless the application is from an institution or a collaboration that has successfully attracted at least £10m of research funding from any source over the past five years (April 2008-March 2013) within the relevant technology area. In addition, the call says applicants will be required to show existing significant support from EPSRC as well as evidence of a substantial financial contribution to the equipment procurement and to the potential to sustain the research.
Further, the EPSRC says individual awards are expected to be in the region of £3 million, however, it also notes that larger bids are encouraged if the applicants have a strong case that “justifies the benefit of this level of investment, if the institution contribution is significant, or if a joint bid is being made by a group of institutions.”
In regard to advanced materials funding, the call describes the EPSRC’s interest as follows:
Advanced materials are instrumental in the generation of long-term economic growth and jobs for the UK and reducing the time required to bring discoveries to the market has been recognized by global competitors in being a key driving force behind a more competitive manufacturing sector and economic growth. Focus should be on materials designed for targeted properties and on seeking to address the aims of this initiative, i.e., reducing lead times, tackling sustainability of materials and discovering new materials types.
The pervasive nature of materials and their application into countless different sectors presents simultaneously both an opportunity and a challenge. Whilst all material areas are included here, we can identify a small number of materials candidates as particular priorities offering the greatest potential to lead to new market opportunities or underpin the competitiveness of high value existing sectors. These include Advanced Composites, Low Energy Electronics (including metamaterials), Materials for Energy, High Performance Alloys, and Nanomaterials for Health.
The main objectives of the call are to:
• Invest in the development and provision of scale-up facilities, including innovative production technologies in advanced manufacturing such as advanced metrology, flow production, laser processing systems, resource efficient technologies, and multifunctional additive layer manufacturing including modeling;
• Invest in characterization of materials at the nanoscale (e.g., atomic force microscopy, scanning electron microscopy).
The deadline for submitting proposals is May 16, 2013, and the call has quite a few more details about the contents of the applications.
A total of £73 million eventually is to be targeted for advanced materials. Besides advanced materials, grid/energy technologies, and robotics, the other five technologies Willetts identifies are big data, space, synthetic biology, regenerative medicine, agri-science.
Photovoltaics based on tiny colloidal quantum dots have several potential advantages over other approaches to making solar cells. But there’s a tradeoff in designing such devices because of two contradictory needs for an effective PV: A solar cell’s absorbing layer needs to be thin to allow charges to pass readily from the sites where solar energy is absorbed to the wires that carry current away—but it also needs to be thick enough to absorb light efficiently. Improved performance in one of these areas tends to worsen the other, says Joel Jean, a doctoral student in MIT’s Department of Electrical Engineering and Computer Science. The addition of zinc oxide nanowires can play a useful role, says Jean, who is the lead author of a paper to be published in the journal Advanced Materials. These nanowires are conductive enough to extract charges easily, but long enough to provide the depth needed for light absorption, Jean says. Using a bottom-up growth process to grow these nanowires and infiltrating them with lead-sulfide quantum dots produces a 50 percent boost in the current generated by the solar cell, and a 35 percent increase in overall efficiency, Jean says. The process produces a vertical array of these nanowires, which are transparent to visible light, interspersed with quantum dots.
(Gizmag) In November 2009, Norwegian state owned electricity company Statkraft opened the world’s first osmotic power plant prototype, which generates electricity from the difference in the salt concentration between river water and sea water. While osmotic power is a clean, renewable energy source, its commercial use has been limited due to the low generating capacities offered by current technology - the Statkraft plant, for example, has a capacity of about 4 kW. Now esearchers have discovered a new way to harness osmotic power that they claim would enable a 1 square meter (10.7 sq. ft.) membrane to have the same 4 kW capacity as the entire Statkraft plant. The global osmotic, or salinity gradient, power capacity, which is concentrated at the mouths of rivers, is estimated by Statkraft to be in the region of 1,600 to 1,700 TWh annually. Electricity can be generated through the osmotic phenomena that results when a reservoir of fresh water is brought into contact with a reservoir of salt water through the use of a special kind of semipermeable membrane in one of two ways—either by harnessing the osmotic pressure differential between the two reservoirs to drive a turbine, or by using a membrane that only allows the passage of ions to produce an electric current.
(NIST Tech Beat) Talk about storing data in the cloud. Scientists at the Joint Quantum Institute (JQI) of the NIST and the University of Maryland have taken this to a whole new level by demonstrating that they can store visual images within quite an ethereal memory device—a thin vapor of rubidium atoms. The effort may prove helpful in creating memory for quantum computers. Their work builds on an approach developed at the Australian National University, where scientists showed that a rubidium vapor could be manipulated in interesting ways using magnetic fields and lasers. The vapor is contained in a small tube and magnetized, and a laser pulse made up of multiple light frequencies is fired through the tube. The energy level of each rubidium atom changes depending on which frequency strikes it, and these changes within the vapor become a sort of fingerprint of the pulse’s characteristics. If the field’s orientation is flipped, a second pulse fired through the vapor takes on the exact characteristics of the first pulse-in essence, a readout of the fingerprint.
Fabricating new plant-based solar cells on cellulose nanocrystal substrates means that they’re recyclable in water. Researchers report that the organic solar cells reach a power conversion efficiency of 2.7 percent, an unprecedented figure for cells on substrates derived from renewable raw materials. The cellulose nanocrystal (CNC) substrates on which the solar cells are fabricated are optically transparent, which lets light pass through them before being absorbed by a very thin layer of an organic semiconductor. During the recycling process, the solar cells are simply immersed in water at room temperature. Within minutes, the CNC substrate dissolves and the solar cell can be separated easily into its major components. To date, organic solar cells have been typically fabricated on glass or plastic. Neither is easily recyclable, and petroleum-based substrates are not very eco-friendly. For instance, if cells fabricated on glass were to break during manufacturing or installation, the useless materials would be difficult to dispose of. ”Our next steps will be to work toward improving the power conversion efficiency over 10 percent, levels similar to solar cells fabricated on glass or petroleum-based substrates,” says Bernard Kippelen, a professor at the Georgia Institute of Technology’s College of Engineering, who led the study. The group plans to achieve this by optimizing the optical properties of the solar cell’s electrode.
As demand for computing and communication capacity surges, the global communication infrastructure struggles to keep pace, since the light signals transmitted through fiber-optic lines must still be processed electronically, creating a bottleneck in telecommunications networks. While the idea of developing an optical transistor to get around this problem is alluring to scientists and engineers, it has also remained an elusive vision, despite years of experiments with various approaches. Now, McGill University researchers have taken a significant, early step toward this goal by showing a new way to control light in the semiconductor nanocrystals known as “quantum dots.” In results published online recently, researchers show that all-optical modulation and basic Boolean logic functionality—key steps in the processing and generation of signals—can be achieved by using laser-pulse inputs to manipulate the quantum mechanical state of a semiconductor nanocrystal. Quantum dots already are used in applications ranging from photovoltaics, to light-emitting diodes and lasers, to biological imaging. Patanjali (Pat) Kambhampati’s McGill group’s, latest findings point toward an important new area of potential impact, based on the ability of these nanocrystals to modulate light in an optical gating scheme. “These results demonstrate the proof of the concept,” Kambhampati says. “Now we are working to extend these results to integrated devices, and to generate more complex gates in hopes of making a true optical transistor.”
A team of researchers has made a major breakthrough in measuring the structure of nanomaterials under extremely high pressures. For the first time, they developed a way to get around the severe distortions of high-energy X-ray beams that are used to image the structure of a gold nanocrystal. The technique, described in Nature Communications, could lead to advancements of new nanomaterials created under high pressures and a greater understanding of what is happening in planetary interiors. Lead author of the study, Wenge Yang of the Carnegie Institution’s High Pressure Synergetic Consortium explains, “The only way to see what happens to such samples when under pressure is to use high-energy X-rays produced by synchrotron sources. Synchrotrons can provide highly coherent X-rays for advanced 3D imaging with tens of nanometers of resolution. This is different from incoherent X-ray imaging used for medical examination that has micron spatial resolution. The high pressures fundamentally change many properties of the material.” The team found that by averaging the patterns of the bent waves-the diffraction patterns-of the same crystal using different sample alignments in the instrumentation, and by using an algorithm developed by researchers at the London Centre for Nanotechnology, they can compensate for the distortion and improve spatial resolution by two orders of magnitude.