Materials can come from the mind, not just the mines

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On February 1, 2008

Dr. Julia E. Medvedeva, assistant professor of physics at Missouri
University of Science and Technology, believes 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

“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

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.

Medvedeva’s research has attracted worldwide attention. She recently gave
invited talks about her research at the Materials Science and Technology
Conference, the International Symposium on Transparent Conducting Oxides, the
Toyota Central Research and Development Laboratory and the Tokyo Institute of

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On February 1, 2008. Posted in Research