Normally, Fang explains, stiffness and strength declines with the density of any material; that’s why when bone density decreases, fractures become more likely. But using the right mathematically determined structures to distribute and direct the loads — the way the arrangement of vertical, horizontal, and diagonal beams do in a structure like the Eiffel Tower — the lighter structure can maintain its strength.
via New ultrastiff, ultralight material developed | MIT News Office.
The ceramic material Powell showed me—which is made of zirconium oxide—replaces the carbon electrode and eliminates those emissions. Researchers have been trying to replace carbon for many years, but the molten salts have corroded the alternatives. The key advance for Infinium was developing alternative molten salts that don’t react with the zirconium oxide, so that it can last long enough to be practical.
via Startup Has a New Way to Make Rare Earths and Other Metals | MIT Technology Review.
Finding an alternative to carbon has long been the “dream” of the metals industry, says Donald Sadoway, a professor of materials science at MIT who is not involved with the company. “I believe [Infinium’s] technology is sound. It’s real,” he says. Whether the company succeeds “is all about the economics,” he says. “No one cares about the flow chart for the process. You care about the prices. If it produces a good metal at a lower cost, people will be interested.”
Thermoelectrics are slabs of semiconductor with a strange and useful property: heating them on one side generates an electric voltage that can be used to drive a current and power devices. To obtain that voltage, thermoelectrics must be good electrical conductors but poor conductors of heat, which saps the effect. Unfortunately, because a material’s electrical and heat conductivity tend to go hand in hand, it has proven difficult to create materials that have high thermoelectric efficiency—a property scientists represent with the symbol ZT.
via Preventing Heat From Going to Waste | Science/AAAS | News.
The key to the ultralow thermal conductivity, Kanatzidis says, appears to be the pleated arrangement of tin and selenium atoms in the material, which looks like an accordion. The pattern seems to help the atoms flex when hit by heat-transmitting vibrations called phonons, thus dampening SbSe’s ability to conduct heat. The researchers report the results today in Nature.
The ultrafast switch is made out of an artificial material engineered to have properties that are not found in nature. In this case, the “metamaterial” consists of nanoscale particles of vanadium dioxide (VO2) – a crystalline solid that can rapidly switch back and forth between an opaque, metallic phase and a transparent, semiconducting phase – which are deposited on a glass substrate and coated with a “nanomesh” of tiny gold nanoparticles.
The scientists report that bathing these gilded nanoparticles with brief pulses from an ultrafast laser generates hot electrons in the gold nanomesh that jump into the vanadium dioxide and cause it to undergo its phase change in a few trillionths of a second.
The secret to the new system: Nanoparticles are embedded in the transparent material. These tiny particles can be tuned to scatter only certain wavelengths, or colors, or light, while letting all the rest pass right through. That means the glass remains transparent enough to see colors and shapes clearly through it, while a single-color display is clearly visible on the glass.
via Seeing things: A new transparent display system could provide heads-up data – MIT News Office.
The Oxford team, led by physicist Henry J. Snaith, made their solar cells using perovskites, a class of mineral-like crystalline materials that has recently grabbed much attention among researchers in photovoltaics. Perovskites have properties similar to inorganic semiconductors and show sunlight-to-electricity conversion efficiencies of more than 15%.
via Solar Cells Could Help Windows Generate Power | Chemical & Engineering News.
Heat makes atoms move and can shake Cooper pairs apart, so the holy grail is to design a material where the pairs are bound together so strongly that superconductivity can happen even up to room temperature. It might be possible to describe a Fermi surface that would create that condition, and perhaps then imagine what crystal structure it would require. “Ideally we would like to be able to tell the materials scientist to put elements X, Y and Z together,” Lee said. “Unfortunately we can’t do that yet.”
via New superconductor theory may revolutionize electrical engineering.
If you want hydrogen to power an engine or a fuel cell, it’s far cheaper to get it from natural gas than to make it by splitting water. Solar power, however, could compete with natural gas as a way to make hydrogen if the solar process were somewhere between 15 and 25 percent efficient, says the U.S. Department of Energy. While that’s more than twice as efficient as current approaches, researchers at Stanford University have recently developed materials that could make it possible to hit that goal. The work is described in the journal Science.
via Artificial Photosynthesis Made Practical | MIT Technology Review.
Recent advances in chemically bonding metal particles allowed the researchers to use silver nanoparticle ink to print the circuits and avoid thermal bonding, or sintering, a time-consuming and potentially damaging technique due to the heat. Printing the circuits on resin-coated paper, PET film and glossy photo paper worked best. Researchers also made a list of materials to avoid, such as canvas cloths and magnet sheets.
via Georgia Tech develops inkjet-based circuits at fraction of time and cost.
From: Ink-Jet Printing Custom-Designed Micro Circuits
Initial reports of the technique, which the team demonstrated at a meeting of the Association for Computing Machinery in Zurich Sept. 10, described the result as a “paper computer,” though the best researchers could do was print a WiFi antenna, circuits for an LED and a 3D-printed flashlight. They also produced circuits containing microprocessors and memory-chip connectors that could potentially become components of an actual device, but the printing, ink and materials are still far too basic to allow that, according to Matt Johnson of conductive-ink manufacturer Bare Conductive, who was quoted in a New Scientist story about the demonstration.
Their findings suggest that it’s possible to alter the electronic properties of a material — for example, changing it from a conductor to a semiconductor — just by changing the laser beam’s polarization. Normally, to produce such dramatic changes in a material’s properties, “you have to do something violent to it,” Gedik says. “But in this case, it may be possible to do this just by shining light on it. That actually modifies how electrons move in this system. And when we do this, the light does not even get absorbed.”
via Persuading light to mix it up with matter – MIT News Office.
It will take some time to assess possible applications, Gedik says. But, he suggests, this could be a way of engineering materials for specific functions. “Suppose you want a material to do something — to conduct electricity, or to be transparent, for example. We usually do this by chemical means. With this new method, it may be possible to do this by simply shining light on the materials.”