SemiconductorThe next generation of feature-filled and energy-efficient electronics will require computer chips just a few atoms thick. For all its positive attributes, trusty silicon can’t take us to these ultrathin extremes.

With two new semiconductors, however, it may be possible.

Electrical engineers have identified two semiconductors—hafnium diselenide and zirconium diselenide—that share or go beyond some of silicon’s desirable traits, starting with the fact that all three materials can “rust.”

“It’s a bit like rust, but a very desirable rust,” says Eric Pop, an associate professor of electrical engineering, who coauthored with postdoctoral scholar Michal Mleczko a paper on the research that appears in the journal Science Advances.

The new materials can also be shrunk to functional circuits just three atoms thick and they require less energy than silicon circuits. Although still experimental, the researchers say the materials could be a step toward the kinds of thinner, more energy-efficient chips demanded by devices of the future.

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Researchers have developed an inexpensive and scalable technique that can change plastic’s molecular structure to help it cast off heat.

Advanced plastics could usher in lighter, cheaper, more energy-efficient product components, including those used in vehicles, LEDs, and computers—if only they were better at dissipating heat.

The concept can likely be adapted to a variety of other plastics. In preliminary tests, it made a polymer about as thermally conductive as glass—still far less so than metals or ceramics, but six times better at dissipating heat than the same polymer without the treatment.

“Plastics are replacing metals and ceramics in many places, but they’re such poor heat conductors that nobody even considers them for applications that require heat to be dissipated efficiently,” says Jinsang Kim, a materials science and engineering professor at the University of Michigan. “We’re working to change that by applying thermal engineering to plastics in a way that hasn’t been done before.”

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GrapheneScientists have turned wood into an electrical conductor by making its surface graphene.

Chemist James Tour of Rice University and his colleagues used a laser to blacken a thin film pattern onto a block of pine. The pattern is laser-induced graphene (LIG), a form of the atom-thin carbon material discovered at Rice in 2014.

“It’s a union of the archaic with the newest nanomaterial into a single composite structure,” Tour says.

Previous iterations of LIG were made by heating the surface of a sheet of polyimide, an inexpensive plastic, with a laser. Rather than a flat sheet of hexagonal carbon atoms, LIG is a foam of graphene sheets with one edge attached to the underlying surface and chemically active edges exposed to the air.

Not just any polyimide would produce LIG, and some woods work better than others, Tour says. The research team tried birch and oak, but found that pine’s cross-linked lignocellulose structure made it better for the production of high-quality graphene than woods with a lower lignin content. Lignin is the complex organic polymer that forms rigid cell walls in wood.

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By: Elton Santos, Queen’s University Belfast

CarbonScientists have found a way to make carbon both very hard and very stretchy by heating it under high pressure. This “compressed glassy carbon”, developed by researchers in China and the US, is also lightweight and could potentially be made in very large quantities. This means it might be a good fit for several sorts of applications, from bulletproof vests to new kinds of electronic devices.

Carbon is a special element because of the way its atoms can form different types of bonds with each other and so form different structures. For example, carbon atoms joined entirely by “sp³” bonds produce diamond, and those joined entirely by “sp²” bonds produce graphite, which can also be separated into single layers of atoms known as graphene. Another form of carbon, known as glassy carbon, is also made from sp² and has properties of both graphite and ceramics.

But the new compressed glassy carbon has a mix of sp³ and sp² bonds, which is what gives it its unusual properties. To make atomic bonds you need some additional energy. When the researchers squeezed several sheets of graphene together at high temperatures, they found certain carbon atoms were exactly in the right position to form sp³ bonds between the layers.

By studying the new material in detail, they found that just over one in five of all its bonds were sp³. This means that most of the atoms are still arranged in a graphene-like structure, but the new bonds make it look more like a large, interconnected network and give it greater strength. Over the small scale of individual graphene sheets, the atoms are arranged in an orderly, hexagonal pattern. But on a larger scale, the sheets are arranged in a disorderly fashion. This is probably what gives it the combined properties of hardness and flexibility.

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GrapheneScientists have created a durable catalyst for high-performance fuel cells by attaching single ruthenium atoms to graphene.

Catalysts that drive the oxygen reduction reaction that lets fuel cells turn chemical energy into electricity are usually made of platinum, which stands up to the acidic nature of the cell’s charge-carrying electrolyte. But platinum is expensive, and scientists have searched for decades for a suitable replacement.

The ruthenium-graphene combination may fit the bill, says chemist James Tour, a professor of computer science and of materials science and nanoengineering at Rice University, whose lab developed the material. In tests, its performance easily matched that of traditional platinum-based alloys and bested iron and nitrogen-doped graphene, another contender.

“Ruthenium is often a highly active catalyst when fixed between arrays of four nitrogen atoms, yet it is one-tenth the cost of traditional platinum,” Tour says. “And since we are using single atomic sites rather than small particles, there are no buried atoms that cannot react. All the atoms are available for reaction.”

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AirplaneA team of researchers has created a new material that could be used in microscopic sensors, also known as microelectromechanical systems [MEMS], for devices that are part of the Internet of Things.

The technological future of everything from cars and jet engines to oil rigs, along with the gadgets, appliances, and public utilities comprising the Internet of Things will depend on these kinds of microscopic sensors. These sensors are mostly made of the material silicon, however, which has its limits.

“For a number of years we’ve been trying to make MEMS out of more complex materials” that are more resistant to damage and better at conducting heat and electricity, says materials scientist and mechanical engineer Kevin J. Hemker of Johns Hopkins University’s Whiting School of Engineering.

Most MEMS devices have internal structures that are smaller than the width of strand of human hair and are shaped out of silicon. These devices work well in average temperatures, but even modest amounts of heat—a couple hundred degrees—causes them to lose their strength and their ability to conduct electronic signals. Silicon is also very brittle and prone to break.

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New research out of the University of Florida shows a new 3D printing technology that could lead to strong, flexible, affordable medical implants.

Through this new process for the use of 3D printing and soft silicone, the researchers believe items that millions of patients use could be more easily manufactured, ranging from implantable bands to soft catheters to slings.

This from the University of Florida:

These kinds of devices are currently molded, which can take days or even weeks to create customized parts designed to fit an individual patient. The 3D-printing method cuts that time to hours, potentially saving lives. What’s more, extremely small and complex devices, such as drainage tubes containing pressure-sensitive valves, simply cannot be molded in one step.

The new method allows them to be printed.

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GrapheneA quantum probe based on an atomic-sized “color center” in diamonds has let researchers observe the flow of electric currents in graphene.

Made up of a lattice of carbon atoms only one atom thick, graphene is a key material for the electronics of the future. The thin carbon material is stronger than steel and due to its flexibility, transparency, and ability to conduct electricity, holds great promise for use in solar cells, touch panels, and flexible electronics.

No one has been able to see what is happening with electronic currents in graphene, says Lloyd Hollenberg, professor at the University of Melbourne and deputy director of the Centre for Quantum Computation and Communication Technology.

According to Hollenberg, this new technique overcomes significant limitations with existing methods for understanding electric currents in devices based on ultra-thin materials.

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Two discoveries could provide a simple and effective way to “stencil” high-quality 2D materials in precise locations and overcome a barrier to their use in next-generation electronics.

In 2004, the discovery of a way to isolate a single atomic layer of carbon—graphene —opened a new world of 2D materials with properties not necessarily found in the familiar 3D world. Among these materials are a large group of elements—transition metals—that fall in the middle of the periodic table.

When atoms of certain transition metals, for instance molybdenum, are layered between two layers of atoms from the chalcogenide elements, such as sulfur or selenium, the result is a three-layer sandwich called a transition metal dichalcogenide. TMDs have created tremendous interest among materials scientists because of their potential for new types of electronics, optoelectronics and computation.

“What we have focused on in this paper is the ability to make these materials over large areas of a substrate in precisely the places we want them,” says Joshua Robinson, associate professor of materials science and engineering at Penn State. “These materials are of interest for a variety of next-generation electronics, not necessarily to replace silicon, but to augment current technologies and ultimately to bring new chip functionality to silicon that we never had before.”

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A team of researchers from the University of Michigan has developed a self-healing, water-repellant coating that is hundreds of times more durable than its counterparts.

The researchers believe this development could help enable waterproof vehicles, clothing, rooftops, and other surfaces – something that current hydrophobic coatings struggle with due to their fragility.

“Thousands of superhydrophobic surfaces have been looked at over the past 20 or 30 years, but nobody has been able to figure out how to systematically design one that’s durable,” says Anish Tuteja, co-author of the study. “I think that’s what we’ve really accomplished here, and it’s going to open the door for other researchers to create cheaper, perhaps even better superhydrophobic coatings.”

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