A Chinese-U.S. research team is exploring the use of metamaterials to create devices that manipulate sound in versatile and unprecedented ways. In a recently published paper, the team reports a simple design for a device, called an acoustic field rotator, which can twist wave fronts inside it so that they appear to be propagating from another direction.
Last year, a physicist and a mechanical engineer at Northeastern Univ. combined their expertise to integrate electronic and optical properties on a single electronic chip, enabling them to switch electrically using light alone. Now, they have built three new devices that implement this fast technology: an AND-gate, an OR-gate and a camera-like sensor made of 250,000 miniature devices.
There is a big effort in industry to produce electrical devices with more and faster memory and logic. Magnetic memory elements, such as in a hard drive, and in the future in what is called MRAM (magnetic random access memory), use electrical currents to encode information. However, the heat which is generated is a significant problem, since it limits the density of devices and hence the performance of computer chips.
An undesired effect in thin film amorphous silicon solar cells has puzzled the scientific community for the last 40 years. This effect, known as light-induced degradation, is responsible for reducing solar cell efficiency over time. Researchers in Germany have recently demonstrated that tiny voids within the silicon network are partly responsible for 10 to 15% efficiency loss as soon as they are used.
A team in France has greatly miniaturized the light-emitting diode (LED) by creating one from a single polythiophene wire placed between the tip of a scanning tunneling microscope and a gold surface. This nanowire, which is made of the same hydrogen, carbon and sulfur components found in much larger LEDs, emits light only when the current passes in a certain direction.
Modern electronics relies on utilizing the charge properties of the electron. The emerging field of atomtronics, however, uses ensembles of atoms to build analogs to electronic circuit elements. Physicists have built a superfluid atomtronic circuit that have allowed them to demonstrate a tool that is critical to electronics: hysteresis. It is the first time that hysteresis has been observed in an ultracold atomic gas.
New research at the Univ. of Arkansas reveals a novel magnetoelectric effect that makes it possible to control magnetism with an electric field. The novel mechanism may provide a new route for using multiferroic materials for the application of RAM (random access memories) in computers and other devices, such as printers.
Engineers are increasingly turning to plasmonic color filters (PCFs) to create and control a broad spectrum of colors for imaging applications. However, PCF light transmission efficiency has been limited to only about 30%, less than half the rate of conventional filters. Researchers have now developed a new PCF scheme that achieves a transmission efficiency of 60 to 70%.
Materials experts in Ireland have developed a new germanium nanowire-based anode that has the ability to greatly increase the capacity and lifetimes of lithium-ion batteries. The typical lithium-ion battery on the market today is based on graphite, which has a relatively low capacity for energy storage. Restructuring the germanium replacement material into nanowires produces a stable, porous battery material.
Lead-free BaTiO3 and KNbO3 ferroelectrics have been known and studied for more than 60 years. However, recent scanning x-ray diffraction studies at Argonne National Laboratory have shown new low-symmetry intermediate phases in these materials that lend a thermotropic character to otherwise well-known phase transitions. The findings show that these transitions in ferroelectrics are closely coupled to the underlying domain microstructure.
An international team of researchers from France and the United States have devised an entirely new way to synthesize graphene ribbons with defined, regular edges, allowing electrons to flow freely through the material. Demonstrating this phenomenon at room temperature, the material was shown to permit electron flow up to 200 times faster than through silicon.
A team of researchers at the Univ. of Delaware has developed a highly selective catalyst capable of electrochemically converting carbon dioxide to carbon monoxide with 92% efficiency. The carbon monoxide then can be used to develop useful chemicals. The exceptionally high activity of the new electrocatalyst is due to its extremely large and highly curved internal surface.
Though piezoelectrics are a widely used technology, there are major gaps in our understanding of how they work. Researchers at NIST and in Canada believe they've learned why one of the main classes of these materials, known as relaxors, behaves in distinctly different ways from the rest and exhibit the largest piezoelectric effect. And the discovery comes in the shape of a butterfly.
Plasmonic nanoparticles developed at Rice Univ. are becoming known for their ability to turn light into heat, but how to use them to generate electricity is not nearly as well understood. Scientists at Rice are working on that, too. They suggest that the extraction of electrons generated by surface plasmons in metal nanoparticles may be optimized and have measured the time plasmon-generated electrons take moving from nanorods to graphene.
Univ. of Houston researchers have developed a new stretchable and transparent electrical conductor, bringing the potential for a fully foldable cell phone or a flat-screen television that can be folded and carried under your arm closer to reality. The researchers report that their gold nanomesh electrodes, produced by the novel grain boundary lithography, increase resistance only slightly, even at a strain of 160%.
Silicon-based electronics have physical limits that slow and may eventually halt the miniaturization of electronic devices. One of the possible solutions is to use molecules as circuits, but their poor conduction capabilities make them unlikely candidates. Researchers in Italy says, however, that the Kondo effect, in which molecules behave like magnetic impurities, could offer a solution.
New research hints that nanodevices in microcircuits can protect themselves from heat generation through the transformation of nanotransistors into quantum states. The finding, demonstrated in nanoscale semiconductors devices, could boost computing power without large-scale changes to electronics.
In only a few years, the efficiency of perovskite-based solar cells has increased from 3% to more than 16%. However, a detailed explanation of the mechanisms of operation within this photovoltaic system is still lacking. in recent work, scientists have now uncovered the mechanism by which these novel light-absorbing semiconductors transfer electrons along their surface.
Researchers in California have created tactile sensors from composite films of carbon nanotubes and silver nanoparticles similar to the highly sensitive whiskers of cats and rats. These new e-whiskers respond to pressure as slight as a single Pascal, about the pressure exerted on a table surface by a dollar bill.
Superconducting quantum interference devices (SQUIDs) are incredibly sensitive magnetic flux sensors which have been limited in their applications because of thermal challenges at ultralow temperatures. Researchers in the U.K. have succeeded in overcoming this difficulty by introducing a new type of nanoscale SQUID based on optimized proximity effect bilayers.
“The interface is the device,” Nobel laureate Herbert Kroemer famously observed, referring to the remarkable properties to be found at the junctures where layers of different materials meet. In today’s burgeoning world of nanotechnology, the interfaces between layers of metal oxides are becoming increasingly prominent. Realizing the vast potential of these metal oxide interfaces requires detailed knowledge of their electronic structure.
For decades, increasing amounts of data have been successfully stored on media with ever-higher densities. Now, an international team has discovered a physical phenomenon that could prove suitable for use in further data aggregation. Researchers found that domain walls, which separate areas in certain crystalline materials, display a polarization, potentially allowing information to be stored in the tiniest of spaces.
Scientists have grown sheets of an exotic material in a single atomic layer and measured its electronic structure for the first time. They discovered it’s a natural fit for making thin, flexible light-based electronics. In the study, the researchers give a recipe for making the thinnest possible sheets of the material, called molybdenum diselenide, in a precisely controlled way, using a technique that’s common in electronics manufacturing.
Researchers in Switzerland are developing electronic components that are thinner and more flexible than before. They can even be wrapped around a single hair without damaging the electronics. This opens up new possibilities for ultra-thin, transparent sensors that are literally easy on the eye.
By replacing platinum with molybdenum in photoelectrochemical cells, scientists from two Swiss labs have developed a cheaper and scalable technique that can greatly improve hydrogen production through water splitting as a means of storing solar energy.