Tag Archives: aluminum

Transparent silver

This March 21, 2017 news item on Nanowerk is the first I’ve heard of transparent silver; it’s usually transparent aluminum (Note: A link has been removed),

The thinnest, smoothest layer of silver that can survive air exposure has been laid down at the University of Michigan, and it could change the way touchscreens and flat or flexible displays are made (Advanced Materials, “High-performance Doped Silver Films: Overcoming Fundamental Material Limits for Nanophotonic Applications”).

It could also help improve computing power, affecting both the transfer of information within a silicon chip and the patterning of the chip itself through metamaterial superlenses.

A March 21, 2017 University of Michigan  news release, which originated the news item, provides details about the research and features a mention about aluminum,

By combining the silver with a little bit of aluminum, the U-M researchers found that it was possible to produce exceptionally thin, smooth layers of silver that are resistant to tarnishing. They applied an anti-reflective coating to make one thin metal layer up to 92.4 percent transparent.

The team showed that the silver coating could guide light about 10 times as far as other metal waveguides—a property that could make it useful for faster computing. And they layered the silver films into a metamaterial hyperlens that could be used to create dense patterns with feature sizes a fraction of what is possible with ordinary ultraviolet methods, on silicon chips, for instance.

Screens of all stripes need transparent electrodes to control which pixels are lit up, but touchscreens are particularly dependent on them. A modern touch screen is made of a transparent conductive layer covered with a nonconductive layer. It senses electrical changes where a conductive object—such as a finger—is pressed against the screen.

“The transparent conductor market has been dominated to this day by one single material,” said L. Jay Guo, professor of electrical engineering and computer science.

This material, indium tin oxide, is projected to become expensive as demand for touch screens continues to grow; there are relatively few known sources of indium, Guo said.

“Before, it was very cheap. Now, the price is rising sharply,” he said.

The ultrathin film could make silver a worthy successor.

Usually, it’s impossible to make a continuous layer of silver less than 15 nanometers thick, or roughly 100 silver atoms. Silver has a tendency to cluster together in small islands rather than extend into an even coating, Guo said.

By adding about 6 percent aluminum, the researchers coaxed the metal into a film of less than half that thickness—seven nanometers. What’s more, when they exposed it to air, it didn’t immediately tarnish as pure silver films do. After several months, the film maintained its conductive properties and transparency. And it was firmly stuck on, whereas pure silver comes off glass with Scotch tape.

In addition to their potential to serve as transparent conductors for touch screens, the thin silver films offer two more tricks, both having to do with silver’s unparalleled ability to transport visible and infrared light waves along its surface. The light waves shrink and travel as so-called surface plasmon polaritons, showing up as oscillations in the concentration of electrons on the silver’s surface.

Those oscillations encode the frequency of the light, preserving it so that it can emerge on the other side. While optical fibers can’t scale down to the size of copper wires on today’s computer chips, plasmonic waveguides could allow information to travel in optical rather than electronic form for faster data transfer. As a waveguide, the smooth silver film could transport the surface plasmons over a centimeter—enough to get by inside a computer chip.

Here’s a link to and a citation for the paper,

High-Performance Doped Silver Films: Overcoming Fundamental Material Limits for Nanophotonic Applications by Cheng Zhang, Nathaniel Kinsey, Long Chen, Chengang Ji, Mingjie Xu, Marcello Ferrera, Xiaoqing Pan, Vladimir M. Shalaev, Alexandra Boltasseva, and Jay Guo. Advanced Materials DOI: 10.1002/adma.201605177 Version of Record online: 20 MAR 2017

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Fireworks for fuel?

Scientists are attempting to harness the power in fireworks for use as fuel according to a Jan. 18, 2017 news item on Nanowerk,

The world relies heavily on gasoline and other hydrocarbons to power its cars and trucks. In search of an alternative fuel type, some researchers are turning to the stuff of fireworks and explosives: metal powders. And now one team is reporting a method to produce a metal nanopowder fuel with high energy content that is stable in air and doesn’t go boom until ignited.

A Jan. 18, 2017 American Chemical Society (ACS) news release, which originated the news item, expands on the theme,

Hydrocarbon fuels are liquid at room temperature, are simple to store, and their energy can be used easily in cars and trucks. Metal powders, which can contain large amounts of energy, have long been used as a fuel in explosives, propellants and pyrotechnics. It might seem counterintuitive to develop them as a fuel for vehicles, but some researchers have proposed to do just that. A major challenge is that high-energy metal nanopowder fuels tend to be unstable and ignite on contact with air. Albert Epshteyn and colleagues wanted to find a way to harness and control them, producing a fuel with both high energy content and good air stability.

The researchers developed a method using an ultrasound-mediated chemical process to combine the metals titanium, aluminum and boron with a sprinkle of hydrogen in a mixed-metal nanopowder fuel. The resulting material was both more stable and had a higher energy content than the standard nano-aluminum fuels. With an energy density of at least 89 kilojoules/milliliter, which is significantly superior to hydrocarbons’ 33 kilojoules/milliliter, this new titanium-aluminum-boron nanopowder packs a big punch in a small package.

Here’s a link to and a citation for the paper,

Optimization of a High Energy Ti-Al-B Nanopowder Fuel by Albert Epshteyn, Michael Raymond Weismiller, Zachary John Huba, Emily L. Maling, and Adam S. Chaimowitz. Energy Fuels, DOI: 10.1021/acs.energyfuels.6b02321 Publication Date (Web): December 30, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

Extending catalyst life for oil and gas

A July 6, 2015 news item on Nanowerk describes the progress on determining exactly how catalysis is achieved when using zeolite (Note: A link has been removed),

Despite decades of industrial use, the exact chemical transformations occurring within zeolites, a common material used in the conversion of oil to gasoline, remain poorly understood. Now scientists have found a way to locate—with atomic precision—spots within the material where chemical reactions take place, and how these spots shut down.

Called active sites, the spots help rip apart and rearrange molecules as they pass through nanometer-sized channels, like an assembly line in a factory. A process called steaming causes these active sites to cluster, effectively shutting down the factory, the scientists reported in Nature Communications (“Determining the location and nearest neighbours of aluminium in zeolites with atom probe tomography”). This knowledge could help devise how to keep the factory running longer, so to speak, and improve catalysts that help produce fuel, biofuel and other chemicals.

A July 6, 2015 Pacific Northwest National Laboratories (PNNL) news release (also on EurekAlert), which originated the news item, describes the collaboration and the research in more detail (Note: Links have been removed),

The team included scientists from the Department of Energy’s Pacific Northwest National Laboratory, petroleum refining technology company UOP LLC and Utrecht University. To make this discovery, they reconstructed the first 3-D atomic map of an industrially relevant zeolite material to track down its key element, aluminum.

When things get steamy, structure changes

Zeolites are minerals made up of aluminum, silicon and oxygen atoms arranged in a three-dimensional crystalline structure. Though they look like white powder to the naked eye, zeolites have a sponge-like network of molecule-size pores. Aluminum atoms along these pores act like workers on an assembly line-they create active sites that give zeolites their catalytic properties.

Industry uses about a dozen synthetic zeolites as catalysts to process petroleum and chemicals. One major conversion process, called fluid catalytic cracking, depends on zeolites to produce the majority of the world’s gasoline. [emphasis mine]

To awaken active sites within zeolites, industry pretreats the material with heat and water, a process called steaming. But too much steaming somehow switches the sites off. Changing the conditions of steaming could extend the catalyst’s life, thus producing fuel more efficiently.

Scientists have long suspected that steaming causes aluminum to move around within the material, thus changing its properties. But until now aluminum has evaded detailed analysis.

Strip away the atoms

Most studies of zeolite structure rely on electron microscopy, which can’t easily distinguish aluminum from silicon because of their similar masses. Worse, the instrument’s intense electron beam tends to damage the material, changing its inherent structure before it’s seen.

Instead, the team of scientists turned to a characterization technique that had never before been successfully applied to zeolites. Called atom probe tomography, it works by zapping a sample with a pulsing laser, providing just enough energy to knock off one atom at a time. Time-of-flight mass spectrometers analyze each atom-at a rate of about 1,000 atoms per second. Unlike an electron microscope, this technique can distinguish aluminum from silicon.

Though atom probe tomography has been around for 50 years, it was originally designed to look at conductive materials, such as metals. Less conductive zeolites presented a problem.

PNNL materials scientist Danny Perea and his colleagues overcame this hurdle by adapting a Local Electrode Atom Probe at EMSL, the Environmental Molecular Sciences Laboratory, a DOE Office of Science User Facility accessible to scientists around the world. Most attempts to image the material ended prematurely, when electromagnetic forces within the instrument vaporized the entire sample. The key to success was to find the right conditions to prepare a sample and then to coat it with a layer of metal to help provide conductivity and strength to withstand analysis.

After hours of blasting tens-of-millions of atoms, the scientists could reconstruct an atomic map of a sample about a thousand times smaller than the width of a human hair. These maps hold clues as to why the catalyst fails.

The news release reveals what the scientists were able to see for the first time,

The images confirmed what scientists have long suspected: Steaming causes aluminum atoms to cluster. Like workers crowded around one spot on the assembly line, this clustering effectively shuts down the catalytic factory.

The scientists even pinpointed the place where aluminum likes to cluster. Zeolite crystals often grow in overlapping sub-units, forming something like a 3-D Venn diagram. Scientists call the edge between two sub-units a grain boundary, and that’s where the aluminum clustered. The scientists suspect that open space along grain boundaries attracted the aluminum.

With the guidance of these atomic maps, industry could one day modify how it steams zeolites to produce a more efficient, longer lasting catalyst. The research team will next examine other industrially important zeolites at different stages of steaming to provide a more detailed map of this transformation.

Here’s a link to and a citation for the paper,

Determining the location and nearest neighbours of aluminium in zeolites with atom probe tomography by Daniel E. Perea, Ilke Arslan, Jia Liu, Zoran Ristanović, Libor Kovarik, Bruce W. Arey, Johannes A. Lercher, Simon R. Bare, & Bert M. Weckhuysen.  Nature Communications 6, Article number: 7589 doi:10.1038/ncomms8589 Published 02 July 2015

This is an open access paper.

RUSNANO (not dead yet) signs MOU with Alcoa

Despite what appear to be some travails noted in my May 17, 2013 posting, RUSNANO (Russian Corporation of Nanotechnologies) is still making deals as reported in a June 21, 2013 news item on Nanowerk,

Alcoa and RUSNANO will produce technologically advanced oil and gas aluminum drill pipe finished with a life-extending antiwear coating under a Memorandum of Understanding (MOU) signed by the companies today. With the help of the Alcoa Technical Center, the parties intend to pursue the potential application of a nanotechnology-based coating for the aluminum drill pipe to enhance its wear resistance in harsh corrosive drilling environments.

Alcoa Chairman and CEO Klaus Kleinfeld and OJSC RUSNANO Chief Executive Officer Anatoly Chubais signed the MOU at the St. Petersburg International Economic Forum.

The June 21, 2013 Alcoa news release, which originated the news item, provides more details,

“Complex oil and gas development projects require drilling equipment with enhanced capabilities,” Chubais said. “Aluminum drill pipe with antiwear nano-coating would enable directional and deep drilling in aggressive, corrosive environments. We expect our joint efforts with Alcoa will create a differentiated product for customers in the oil and gas industry.”

Mr. Kleinfeld added, “Alcoa’s deep technological capabilities, combined with the expertise of our partner RUSNANO, will open new opportunities for developing the aluminum industry in Russia. Alcoa is setting a high standard for innovation and extending our product range in the oil and gas segment.”

With facilities in Samara and Belaya Kalitva, Alcoa is Russia’s largest producer of fabricated aluminum, manufacturing a wide range of flat rolled products, forgings and extrusions for a variety of end markets including aerospace and automotive. [emphasis mine] Under terms of the MOU, Alcoa will leverage its Samara facility to produce aluminum drill pipe with hot fit tool joints for the country’s oil and gas market. RUSNANO Capital, a subsidiary of OJSC RUSNANO, will contribute capital.

The antiwear nano-coating is expected to extend the life of the aluminum pipe by approximately 30% to 40% in aggressive and corrosive drilling environments compared to uncoated aluminum pipe.

Here’s a little more about the two principles, Alcoa and about RUSNANO, from the news release,

About Alcoa

Alcoa is the world’s leading producer of primary and fabricated aluminum, as well as the world’s largest miner of bauxite and refiner of alumina. In addition to inventing the modern-day aluminum industry, Alcoa innovation has been behind major milestones in the aerospace, automotive, packaging, building and construction, commercial transportation, consumer electronics and industrial markets over the past 125 years. Among the solutions Alcoa markets are flat-rolled products, hard alloy extrusions, and forgings, as well as Alcoa® wheels, fastening systems, precision and investment castings, and building systems in addition to its expertise in other light metals such as titanium and nickel-based super alloys. Sustainability is an integral part of Alcoa’s operating practices and the product design and engineering it provides to customers. Alcoa has been a member of the Dow Jones Sustainability Index for 11 consecutive years and approximately 75 percent of all of the aluminum ever produced since 1888 is still in active use today. Alcoa employs approximately 61,000 people in 30 countries across the world. …

In 2005, the Company acquired two of Russia’s largest fabricating facilities: Samara Metallurgical Plant (now ZAO Alcoa SMZ) and Belaya Kalitva Metallurgical Production Association (now ZAO AMR). [emphasis mine]

About RUSNANO

RUSNANO was founded in March 2011 as an open joint stock company through reorganization of state corporation Russian Corporation of Nanotechnologies. RUSNANO’s mission is to develop the Russian nanotechnology industry through co-investment in nanotechnology projects with substantial economic potential or social benefit. The Government of the Russian Federation owns 100 percent of the shares in RUSNANO. Anatoly Chubais is CEO and chairman of the Executive Board of RUSNANO.

Work to establish nanotechnology infrastructure and training for nanotechnology specialists, formerly conducted by the Russian Corporation of Nanotechnologies, has been entrusted to the Fund for Infrastructure and Educational Programs, a non-commercial fund also established through reorganization of the Russian Corporation of Nanotechnologies.

As for the 2011 founding date for RUSNANO, that appears to be the date it became an open stock company. Here’s more according to the RUSNANO Wikipedia essay (Note: Links and footnotes have been removed),

A law (On the Russian Nanotechnology Corporation) which resulted in the creation of “Russian Corporation of Nanotechnologies” was proposed by several members of the United Russia party on June 2007. The proposal passed its first reading in the State Duma on June 14 and final reading on July 4. The upper house, the Federation Council, approved it on July 6. Initially organised as a state corporation, the company was re-registered on March 11, 2011 as open joint-stock company RUSNANO.

In any event, I’m keeping an eye on RUSNANO as it continues to evolve in the midst of what appears to be a more than usually volatile period for Russia’s state business enterprises.