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By adding tungsten to vanadium oxide, Texas A&M researchers found they could better control, or tune, the material's transition to and from conductor to insulator -- properties that could be exploited in powering future computers. (Credit: Erick J. Braham.)

COLLEGE STATION --

Researchers from Texas A&M University report significant advances in their understanding and control of a chameleon-like material that could be key to developing next-generation computers that are even more powerful than today's silicon-based machines.

The existing paradigm of silicon-based computing has given us a range of amazing technologies, but engineers are starting to discover silicon's limits. As a result, for computer science to keep advancing, it is important to explore alternative materials that could enable different ways to do computation, according to Dr. Patrick J. Shamberger, assistant professor in the Department of Materials Science and Engineering. Vanadium dioxide is one example.

"It's a very interesting, chameleon-like material that can easily switch between two different phases, from being an insulator to being a conductor, as you heat and cool it or apply a voltage," said Dr. Sarbajit Banerjee, a professor in the Department of Chemistry and an affiliated member of Materials Science and Engineering. "And if you think about those two phases as being analogous to a zero and a one, you can come up with some interesting new ways of information processing."

Banerjee and Shamberger are corresponding authors of a paper describing their work, which was published in the January 2018 issue of Chemistry of Materials.

"Before vanadium dioxide can be used in computing, we need to better control its transition from insulator to conductor and back again," Shamberger said.

In the paper, the team describes doing just that by adding tungsten to the material. Among other things, they showed that tungsten allows the transition to occur over two very different pathways. The result is that the transition from insulator to conductor happens easily and quickly, while the transition from conductor back to insulator is more difficult.

"Think of it as driving from point A to point B and back again," Banerjee said. "Going there, you take a superhighway, but coming back, you're on back roads."

Essentially the addition of tungsten allows the vanadium oxide to switch quickly in one direction and much more slowly in the other -- phenomena that could be exploited in future computers.

"It provides an additional 'knob' to tune how you go back and forth between the two states," said Erick J. Braham, a Texas A&M chemistry graduate student and member of the Banerjee Laboratory who was first author on the paper.

The team has also found that the addition of tungsten allows them to better control, or tune, the different temperatures where the transitions occur.

Banerjee notes the interdisciplinary nature of the work, which involved four groups with expertise ranging from computational materials science to electron microscopy, has been key.

"We've really looked at this puzzle from different ends to try to make sense of exactly what's going on," he said. "It's been very exciting."

Additional authors from Texas A&M are Dr. Raymundo Arróyave from materials science and engineering; Nathan A. Fleer, graduate student in chemistry and materials science and engineering; Diane Sellers, assistant research scientist in chemistry and materials science and engineering; Ruben Villarreal, graduate student in materials science and engineering; and Katie E. Farley and Emily Emmons, both former graduate students. Authors from the University of Illinois at Chicago are Dr. Reza Shahbazian-Yassar, professor, and Hasti Asayesh-Ardakani, a visiting researcher. Their work was supported by the National Science Foundation and the Air Force Office of Scientific Research.

To learn more about Banerjee and his research, visit http://www.chem.tamu.edu/faculty/sarbajit-banerjee/.

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About Research at Texas A&M University: As one of the world's leading research institutions, Texas A&M is at the forefront in making significant contributions to scholarship and discovery, including that of science and technology. Research conducted at Texas A&M represented annual expenditures of more than $892.7 million in fiscal year 2016, ranking Texas A&M in the top 20 of the National Science Foundation's Higher Education Research and Development survey (2016). Texas A&M's research creates new knowledge that provides basic, fundamental and applied contributions resulting in many cases in economic benefits to the state, nation and world. To learn more, visit http://research.tamu.edu.

-aTm-

Contact: Shana K. Hutchins, (979) 862-1237 or shutchins@science.tamu.edu or Dr. Sarbajit Banerjee, (979) 862-3102 or banerjee@chem.tamu.edu

Elizabeth Thomson

  • (From left:) Erick J. Braham, Dr. Diane Sellers, Dr. Sarbajit Banerjee and Dr. Patrick J. Shamberger. (Credit: Texas A&M Materials Science and Engineering.)

  • Sellers and Braham (above and below) in the Banerjee Laboratory. (Credit: Texas A&M Materials Science and Engineering.)

  • Dr. Sarbajit Banerjee

  • Dr. Patrick J. Shamberger

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