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February 12th, 2013

Other materials stories that may be of interest

Published on February 12th, 2013 | By: Eileen De Guire

Elsewhere on the materials front:

Microscopic dendrites a focus in Boeing Dreamliner probe

(Wall Street Journal) Aviation safety investigators are examining whether the formation of microscopic structures known as dendrites inside the Boeing Co. 787’s lithium-ion batteries played a role in twin incidents that prompted the fleet to be grounded nearly a month ago. The new information from the National Transportation Safety Board offers a glimpse into what could become an important line of inquiry for the investigation into a Jan. 7 battery fire aboard a Japan Airlines Co. Dreamliner parked in Boston. Investigators have so far said they know that fire was triggered by short circuits, but haven’t been able to determine the original cause of the incident, or of another one in which an overheating battery forced an All Nippon Airways Co. in Japan to make an emergency landing. Japanese investigators have said the battery in that ANA incident also experienced an internal short-circuit and a “thermal runaway.” Dendrites are tiny deposits of lithium resembling microscopic whiskers that can grow within the cells of a battery, potentially causing short circuits and significant heat and even fire. They are often a byproduct of rapid or uneven charging of lithium-ion batteries, according to experts.

New classes of magnetoelectric materials promise advances in computing technology

Thanks to new research by an international team of researchers led by the DOE’s Argonne National Laboratory, physicists have developed new methods for controlling magnetic order in a particular class of materials known as “magnetoelectrics.” Magnetoelectrics get their name from the fact that their magnetic and electric properties are coupled to each other. Because this physical link potentially allows control of their magnetic behavior with an electrical signal or vice versa, scientists have taken a special interest in magnetoelectric materials. The Argonne-led team focused on europium-titanium oxide, which has a simple atomic structure that suited it especially well to the experiment. The titanium atom sits in the middle of a cage constructed of the europium and oxygen atoms. By first compressing the cage through growing a thin film of EuTiO3 on a similar crystal with a smaller lattice and then applying a voltage, the titanium shifts slightly, electrically polarizing the system, and more importantly, changing the magnetic order of the material.

KIT Spin-off “Nanoscribe” demonstrates high-speed 3D printer

At the Photonics West, the leading international fair for photonics, a spin-off of Karlsruhe Institute of Technology (KIT), presented the world’s fastest 3D printer of micro- and nanostructures. With this printer, the smallest three-dimensional objects, often smaller than the diameter of a human hair, can be manufactured with minimum time consumption and maximum resolution. The printer is based on a novel laser lithography method. “The success of Nanoscribe is an example of KIT’s excellent entrepreneurial culture and confirms our strategy of specifically supporting spin-offs. In this way, research results are transferred rapidly and sustainably to the market,” says Peter Fritz, KIT vice president for research and innovation. In early 2008, Nanoscribe was founded as the first spin-off of KIT and has since established itself as the world’s market and technology leader in the area of 3D laser lithography. With the new laser lithography method, printing speed is increased by factor of about 100. This increase in speed results from the use of a galvo mirror system, a technology that is also applied in laser show devices or scanning units of CD and DVD drives. Reflecting a laser beam off the rotating galvo mirrors facilitates rapid and precise laser focus positioning.

New world record efficiency (10.7 percent conversion rate) for thin film silicon solar cells

The Photovoltaics-Laboratory of EPFL’s Insitute of Microengineering is well known as a pioneer in the development of thin-film silicon solar cells, and as a precursor in the use of microcrystalline silicon as a photoactive material in thin-film silicon photovoltaic devices. A remarkable step was achieved by the team led by Fanny Meillaud and Matthieu Despeisse with a new world record efficiency of 10.7 percent for a single-junction microcrystalline silicon solar cell, independently confirmed at Fraunhofer Institute for Solar Energy Systems. Importantly, the employed processes can be up-scaled to the module level. While standard wafer-based crystalline silicon PV technology implements absorber layers with a thickness of about 180 micrometers for module conversion efficiency of 15 to 20 percent, 10.7% efficiency was reached here with only 1.8 micrometers of silicon material, i.e. 100 times less material than for conventional technologies, and with cell fabrication temperature never exceeding 200°C.

PNAS: Energy systems transformation

The contemporary industrial metabolism is not sustainable. Critical problems arise at both the input and the output side of the complex: Although affordable fossil fuels and mineral resources are declining, the waste products of the current production and consumption schemes (especially CO2 emissions, particulate air pollution, and radioactive residua) cause increasing environmental and social costs. Most challenges are associated with the incumbent energy economy that is unlikely to subsist. However, the crucial question is whether a swift transition to its sustainable alternative, based on renewable sources, can be achieved. The answer requires a deep analysis of the structural conditions responsible for the rigidity of the fossil-nuclear energy system. We argue that the resilience of the fossil-nuclear energy system results mainly from a dynamic lock-in pattern known in operations research as the “Success to the Successful” mode. The present way of generating, distributing, and consuming energy-the largest business on Earth-expands through a combination of factors such as the longevity of pertinent infrastructure, the information technology revolution, the growth of the global population, and even the recent financial crises: Renewable-energy industries evidently suffer more than the conventional-energy industries under recession conditions. Our analysis indicates that the rigidity of the existing energy economy would be reduced considerably by the assignment of unlimited liabilities to the shareholders.

Spotting the invisible cracks in wind turbines

Physicists at the University of Oldenburg, Germany, have now developed a new method for analysing the elastic characteristics of mechanical structures subjected to disturbances, akin to the turbulences affecting wind turbines. A significant percentage of the costs of wind energy is due to wind turbine failures, as components are weakened under turbulent air flow conditions and need to be replaced. The challenge for the team was to find a method for detecting fatigue in the wind turbines’ parts without having to remove each of the components and while the turbine is in operation. Until now, standard methods have relied on so-called spectral analysis, which looks at the different frequency response. But these measurements are distorted by the turbulent working conditions. As a result, these detection methods often only detect really major damages, like a crack that covers more than 50 percent of a blade. The authors used a simple experimental set-up of undamaged and damaged beam structures and exposed them to excitations containing an element of interfering vibrations, or noise, made by different turbulent wind conditions.

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