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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Focus IssuesThe ECS Journal of Solid State Science and Technology is now featuring a focus issue on Thermoelectric Materials & Devices: Phonon Engineering, Advanced Materials and Thermal Transport. The issue reflects the symposia from the 228th ECS Meeting on Thermoelectric and Thermal Interface Materials in Phoenix, AZ.

In the issue’s preface, the authors tell us that advances in this field, “. . . can inspire developments in thermoelectrics that may underpin the next major advance in energy harvesting and cooling and ultimately improve the quality of our devices, and help drive energy efficiency and a greener society.”

The focus issue discusses advances, challenges, and applications in thermoelectrics and its various sub-fields such as phonon transport physics, materials science, electronics, condensed matter physics, engineering, the chemistry of materials, and processing technology.

The Society would like to thank the authors, reviewers, and editors who contributed to this focus issue. Special thank you to Colm O’Dwyer from University College Cork, Renkun Chen from the University of California, San Diego, Jr-Hau He from King Abdulla University of Science and Technology, Jaeho Lee from the University of California Irvine, and Kafil M. Razeeb from University College Cork.

Read the focus issue in the ECS Digital Library.

Modified Cathode

Cathode particles treated with the carbon dioxide-based mixture show oxygen vacancies on the surface.
Image: Laboratory for Energy Storage and Conversion, UC San Diego

An international team of researchers has recently demonstrated a 30 to 40 percent increase in the energy storage capabilities of cathode materials.

The team, led by ECS member and 2016 Charles W. Tobias Young Investigator Award winner, Shirley Meng, has successfully treated lithium-rich cathode particles with a carbon dioxide-based gas mixture. This process introduced oxygen vacancies on the surface of the material, allowing for a huge boost to the amount of energy stored per unit mass and proving that oxygen plays a significant role in battery performance.

This greater understanding and improvement in the science behind the battery materials could accelerate developments in battery performance, specifically in applications such as electric vehicles.

(READ: “Gas-solid interfacial modification of oxygen activity in layered oxide cathodes for lithium-ion batteries“)

“We’ve uncovered a new mechanism at play in this class of lithium-rich cathode materials,” says Meng, past guest editor of JES Focus Issue on Intercalation Compounds for Rechargeable Batteries. “With this study, we want to open a new pathway to explore more battery materials in which we can control oxygen activity.”

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Sustainable Battery

The new carbon-based material for sodium-ion batteries can be extracted from apples.
Image: KIT

The saying goes: an apple a day keeps the doctor away; but in this case, an apple may be the answer to the next generation of energy storage technology.

ECS member Stefano Passerini of the Karlsruhe Institute of Technology is leading a study to extract carbon-based materials for sodium-ion batteries from organic apple waste.

Developing batteries from waste

This new development could help reduce the costs of future energy storage systems by applying a cheap material with excellent electrochemical properties to the already promising field of sodium-ion batteries.

(MORE: Read more research by Passerini.)

Many researchers are currently looking to sodium-ion batteries as the next generation of energy storage, with the ability to outpace the conventional lithium-ion battery.

The future of sodium-ion batteries

Interest in sodium-ion batteries dates back to the 1980s, but discoveries haven’t taken off until recently. Researchers are now finding way to combat low energy densities and short life cycles through using novel materials such as apples.

(MORE: Read the full paper in ChemElectroChem.)

Sodium-ion batteries could prove to be the next big thing in large scale energy storage due to the high abundance of materials used in development and the relatively low costs involved.

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Graphene for Next-Gen Night Vision

Graphene is called the “wonder material” with good reason. The material hosts a slew of unique chemical and physical properties, with applications from fuel cells to biomedical to energy storage.

Now, a team from MIT is taking the material and applying it to infrared sensors to create next-gen night vision goggles. Additionally, the team is looking to take that same technology and apply it to high-tech windshields and smartphones.

We achieve night vision capabilities through thermal imaging that allows people to see otherwise invisible infrared rays that are shed as heat. This technology is useful for many different applications, such as assisting soldiers and firefighters in their duty. While night vision devices currently exist, they need bulky cooling systems to create a useful image.

Because of graphene’s electrical qualities, researchers have known that the material would be an excellent infrared detector. The team at MIT took this idea and moved forwarding in creating a less bulky night vision goggle through the utilization of graphene.

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Breakthrough in Polishing of Silicon Carbide

Microscopic interferometric images and slope images of SiC surface (a) before (PV: 23.040 nm, Ra: 1.473 nm, RMS: 1.885 nm) and (b) after (PV: 2.070 nm, Ra: 0.198 nm, RMS: 0.247 nm) polishing with soda-lime glass plate.

Microscopic interferometric images and slope images of SiC surface (a) before (PV: 23.040 nm, Ra: 1.473 nm, RMS: 1.885 nm) and (b) after (PV:
2.070 nm, Ra: 0.198 nm, RMS: 0.247 nm) polishing with soda-lime glass plate.

Guest post by Jennifer Bardwell, Technical Editor of the ECS Journal of Solid State Science and Technology (JSS).

This paper, from Kumamoto University in Japan, concerns a technique for abrasive-free polishing of silicon carbide (SiC). This topic is timely as SiC is an important material for wide bandgap electronics, both in its own right, and as a substrate for gallium nitride electronics. The reviewers note that:

“Defect free polishing of SiC surface has high significance” and that “The results are amazing”

In the words of the abstract: “The experimental results showed that an oxide layer was formed on the SiC surface as a result of the chemical reaction between the interfaces of the synthetic SiO2 glass plate and the SiC substrate. This generated oxide layer was effectively removed by polishing with the soda-lime SiO2 glass plate, resulting in an atomically smooth SiC surface with a root mean square roughness of less than 0.1 nm for 1.5 h. Obtained experimental results indicate that the component materials, temperature and water adsorptive property of the soda-lime SiO2 glass play an important role in the removal of the tribochemically generated layer on the SiC surface during this polishing.”

Read the paper.

Novel Concrete Can Heal Itself

Concrete is the world’s most popular building material, but the material’s durability deteriorates over years allowing for potentially devastating consequences. One researcher from Delft University of Technology, Henk Jonkers, has made it his mission to combat this issue by developing a “living concrete.”

Jonkers’ development has produced a new type of concrete that can fix its own cracks by using a bacteria healing agent.

“We are combining nature with construction materials,” said Jonkers.

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New Type of Graphene Aerogel (Video)

focus-issue-boxLogan Streu, ECS Content Associate & Assistant to the CCO, recently spotted an article out of Lawrence Livermore National Laboratory detailing a new type of graphene aerogel that could improve energy storage, sensors, nanoelectronics, catalysis, and separations.

The researchers are creating graphene aerogel microlattics through a 3D printing process known as direct ink wetting.

This from Lawrence Livermore National Laboratory:

The 3D printed graphene aerogels have high surface area, excellent electrical conductivity, are lightweight, have mechanical stiffness and exhibit supercompressibility (up to 90 percent compressive strain). In addition, the 3D printed graphene aerogel microlattices show an order of magnitude improvement over bulk graphene materials and much better mass transport.

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corrosion_blog_interfaceAn article by Kenji Amaya, Naoki Yoneya, and Yuki Onishi published in the latest issue of Interface.

Protecting structures from corrosion is one of the most important challenges in engineering. Cathodic protection using sacrificial anodes or impressing current from electrodes is applied to many marine structures. Prediction of the corrosion rates of structures and the design of cathodic protection systems have been traditionally based on past experience with a limited number of empirical formulae.

Recently, application of numerical methods such as the boundary element method (BEM) or finite element method (FEM) to corrosion problems has been studied intensively, and these methods have become powerful tools in the study of corrosion problems.

With the progress in numerical simulations, “Inverse Problems” have received a great deal of attention. The “Inverse Problem” is a research methodology pertaining to identifying unknown information from external or indirect observation utilizing a model of the system.

Read the rest.

computer_simulation2An article by N.J. Laycock, D.P. Krouse, S.C. Hendy, and D.E. Williams published in the latest issue of Interface.

Stainless steels and other corrosion resistant alloys are generally protected from the environment by ultra-thin layers of surface oxides, also called passive films. Unfortunately, these films are not perfect and their Achilles’ heel is a propensity to catastrophic local breakdown, which leads to rapid corrosion of the metallic substructure. Aside from the safety and environmental hazards associated with these events, the economic impact is enormous.

In the oil and gas and petrochemical industries, it is of course usually possible to select from experience a corrosion-resistant alloy that will perform acceptably in a given service environment. This knowledge is to a large extent captured in industry or company-specific standards, such as Norsok M1.

However, these selections are typically very conservative because the limits tend to be driven by particular incidents or test results, rather than by fundamental understanding. Decision-making can be very challenging, especially in today’s mega-facilities, where the cost of production downtime is often staggeringly large. Thus significant practical benefits could be gained from reliable quantitative models for pitting corrosion of stainless steels. There have been several attempts to develop purely stochastic models of pitting corrosion.

Read the rest.

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