David Kirkpatrick

July 22, 2010

Improving the application of nanocoatings

Nanocoatings do a lot of good, particularly with making solar cells more efficient. The trick is they haven’t been too easy to apply to big areas. Researchers at Stanford have helped change that issue.

From the link:

Nanoscale wires, pores, bumps, and other textures can dramatically improve the performance of solar cells, displays, and even self-cleaning coatings. Now researchers at Stanford University have developed a simpler, cheaper way to add these features to large surfaces.

Nanoscale structures offer particular advantages in devices that interact with light. For example, a thin-film solar cell carpeted with nano pillars is more efficient because the pillars absorb more light and convert more of it into electricity. Other nanoscale textures offer similar advantages in optical devices like display backlights.

The problem is scaling up to large areas, says Yi Cui, a Stanford professor of materials science and engineering who led the new work. “Many methods are really complex and don’t solve the problem,” says Cui. Lithography can be used to carve out nanoscale features with precise dimensions, but it’s expensive and difficult. Simpler techniques, such as spin-coating a surface with nanoparticles or using acids to etch it with tiny holes, don’t allow for much precision.

Nanosphere smear: Using a spinning rod to deposit an ink suspension of silica nanospheres is a simple way to create bumpy, nanotextured coatings like these three.

Credit: ACS/Nano Letters

July 15, 2010

Nanotech improves submarine sonar

Filed under: et.al. — Tags: , , , , , — David Kirkpatrick @ 2:05 am

Carbon nanotubes really are an amazing material.

The release:

Submarines could use new nanotube technology for sonar and stealth

IMAGE: Submarines of the future could be equipped with “nanotube speakers ” to help improve sonar to probe the ocean depths and make the vessels invisible to enemies.

Click here for more information.

Speakers made from carbon nanotube sheets that are a fraction of the width of a human hair can both generate sound and cancel out noise — properties ideal for submarine sonar to probe the ocean depths and make subs invisible to enemies. That’s the topic of a report on these “nanotube speakers,” which appears in ACS’ Nano Letters, a monthly journal.

Ali Aliev and colleagues explain that thin films of nanotubes can generate sound waves via a thermoacoustic effect. Every time that an electrical pulse passes through the microscopic layer of carbon tubes, the air around them heats up and creates a sound wave. Chinese scientists first discovered that effect in 2008, and applied it in building flexible speakers. In a remarkable demonstration, which made its way onto YouTube, the Chinese nanoscientists stuck a sheet of nanotubes onto the side of a flag, and attached it to an mp3 player. They used the nanotube-coated flag to play a song while it flapped in the breeze. But they did not test its ability to operate under water.

Aliev’s group took that step, showing that nanotube sheets produce the kind of low-frequency sound waves that enable sonar to determine the location, depth, and speed of underwater objects. They also verified that the speakers can be tuned to specific frequencies to cancel out noise, such as the sound of a submarine moving through the depths.

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ARTICLE FOR IMMEDIATE RELEASE “Underwater Sound Generation Using Carbon Nanotube Projectors”

DOWNLOAD FULL TEXT ARTICLE http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/nl100235n

March 11, 2010

Mass producing graphene cheaply

Filed under: Business, Science, Technology — Tags: , , , — David Kirkpatrick @ 12:36 pm

Commercial production of graphene is coming and we can expect to see some of those “miracle material” claims begin to show fruition.

The release:

A huge step toward mass production of coveted form of carbon

IMAGE: This graphic represents an atom-thin sheet of graphene, a form of carbon that could replace silicon in future electronic devices. Scientists have developed a simple manufacturing method that could allow…

Click here for more information.

Scientists have leaped over a major hurdle in efforts to begin commercial production of a form of carbon that could rival silicon in its potential for revolutionizing electronics devices ranging from supercomputers to cell phones. Called graphene, the material consists of a layer of graphite 50,000 times thinner than a human hair with unique electronic properties. Their study appears in ACS’ Nano Letters, a monthly journal.

Victor Aristov and colleagues indicate that graphene has the potential to replace silicon in high-speed computer processors and other devices. Standing in the way, however, are today’s cumbersome, expensive production methods, which result in poor-quality graphene and are not practical for industrial scale applications.

Aristov and colleagues report that they have developed “a very simple procedure for making graphene on the cheap.” They describe growing high-quality graphene on the surface of commercially available silicon carbide wafers to produce material with excellent electronic properties. It “represents a huge step toward technological application of this material as the synthesis is compatible with industrial mass production,” their

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ARTICLE FOR IMMEDIATE RELEASE “Graphene Synthesis on Cubic SiC/Si Wafers. Perspectives for Mass Production of Graphene-Based Electronic Devices”

DOWNLOAD FULL TEXT ARTICLE http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/nl904115h