Materials can come from the mind, not just the mines

Medvedeva is examining how such properties as optical transparency or electrical conductivity depend on how the atoms are put together on the microscopic level. Such in-depth understanding of underlying physical phenomena allows her to design new materials with properties required for a particular application.

“Right now, we are experiencing a materials revolution,” Medvedeva says. “Advanced materials have already transformed the lives of millions of people around the globe. Now, supercomputers facilitate the progress toward even more high-tech innovations.”

Until recently, scientists concentrated on understanding materials that exist in nature or are prepared in a laboratory. Now, the advent of ever-more-powerful supercomputers and the development of state-of-the-art computational approaches make it possible for researchers to simulate new materials and manipulate their properties based on knowledge of the atomic composition and the spatial arrangement of the atoms.

Such computational “experiments” allow Medvedeva to speed up the search for materials with optimal performance for a specific application – something that could have taken years to achieve using trial-and-error experimental techniques.

In particular, Medvedeva is interested in a unique class of materials called transparent conductors, which share the seemingly contradictory properties of being optically transparent, like glass, and electrically conductive, like metal. Transparent conductors are vital components in many devices, including solar cells, smart windows, flat-panel and flexible displays, invisible, or “see-through,” electronics and gas sensors. Despite the multitude of applications and the growing demand for such devices, only four materials are known to be good transparent conductors – doped zinc, indium, cadmium and tin oxides. Of the four, only two are used commercially.

Although relatively simple compounds, all of the known transparent conductors require sophisticated preparation techniques to achieve optimal balance between sufficient optical transparency and useful electrical conductivity. There are other drawbacks to these

compounds, as well. Due to the increased demand, some of the oxides have become expensive. For example, the cost of indium rose 10-fold from 2002 to 2006. Besides, indium and cadmium are highly toxic.

With financial support from the National Science Foundation (NSF) and the Petroleum Research Fund of the American Chemical Society, Medvedeva is working to develop new transparent conductor materials that are more efficient, easier to fabricate, less expensive and environmentally friendly. Medvedeva’s preliminary research shows that with proper preparation calcium, aluminum or silicon oxides, the most abundant substances in the Earth’s crust, can be made electrically conductive while maintaining their superior optical properties. Further studies of these materials are underway.

To help with this effort, Medvedeva has also received computational grants that give her access to national supercomputer facilities, the National Energy Research Scientific Computing Center and TeraGrid Cluster, supported by the Department of Energy and NSF.

Source: Missouri University

Hydrogen generation without the carbon footprint
A greener, less expensive method to produce hydrogen for fuel may eventually be possible with the help of water, solar energy and nanotube diodes that use the entire spectrum of the sun's energy, according to Penn State researchers.
Transparent Semiconductors May Be Future of Flat Panel Display Industry
Some types of “amorphous oxide” transparent semiconductors originally developed in the College of Engineering at Oregon State University may form the basis for the next generation of flat panel displays, providing better performance at a lower cost.
Research helps understand factors that influence efficiency of organic-based devices
Organic-based devices, such as organic light-emitting diodes, require a transparent conductive layer with a high work function, meaning it promotes injection of electron holes into an organic layer to produce more light.
'Public' online spaces don't carry speech, rights
(AP) -- Rant all you want in a public park. A police officer generally won't eject you for your remarks alone, however unpopular or provocative. Say it on the Internet, and you'll find that free speech and other constitutional rights are anything but guaranteed.
US Pharmacopeia announces revised heparin monographs and reference standards
Standards updated in response to public health threat associated with blood-thinning drug's adulteration with over-sulfated chondroitin
The U.S. Pharmacopeial (USP) Convention announces that revised monographs for heparin sodium and heparin calcium in the United States Pharmacopeia (USP) are now available and official on the USP Web site. The revised monographs are accompanied by two new and two updated official USP Reference Standards. These public standards allow any party—and particularly the Food and Drug Administration (FDA) and manufacturers—to test heparin sodium and calcium drug substances to assure their quality. All drug manufacturers who market heparin in the United States are required to meet these newly revised standards. The heparin monographs were updated in the interest of public health following the deaths of more than 200 people earlier this year. These deaths are suspected to have resulted from the adulteration of the blood thinner with over-sulfated chondroitin, which is derived from the chemical chondroitin and used in dietary supplements.
OSU's Transparent Electronics Key to Solar Energy Breakthrough
Transparent transistors and optoelectronics created by researchers at Oregon State University and HP have found their first key industrial application in a new type of solar energy system that its developers say will be four times more cost-efficient than any existing technology.
Perfecting a solar cell by adding imperfections
Nanotechnology is paving the way toward improved solar cells. New research shows that a film of carbon nanotubes may be able to replace two of the layers normally used in a solar cell, with improved performance at a lower cost. Researchers have found a surprising way to give the nanotubes the properties they need: add defects.
Testing, Radiation Testing: Northwestern Transistors On Space Station
Transistors based on a new kind of material created by Northwestern University researchers have been lifted into outer space on the space shuttle Endeavour and attached to the outside of the International Space Station for radiation testing.

Materials can come from the mind, not just the mines

Related stories:

News discussion: