Scientia: Research at the University of Tennessee
Under One Roof
By CATHERINE LONGMIRE
UT’s Joint Institute for Advanced Materials will recruit scientists and engineers from across disciplines to design novel materials and, in the process, create a first-rate facility
Settled in East Tennessee’s Knox County, Cherokee Farm is a rolling expanse anchored by silos and barns and dotted with Holstein cattle—a sleepy spot cradled in a bend of the Tennessee River. Long a headquarters for agricultural research, the farm may seem a surprising place to revolutionize materials science. Yet this pastoral backdrop is where the University of Tennessee and Oak Ridge National Laboratory will build a program dedicated to doing just that.
The Joint Institute for Advanced Materials (JIAM) represents a fresh approach to scientific thinking: pulling together scientists and engineers from across disciplines to design novel materials and weave them into the economy. JIAM will give these researchers the space and state-of-the-art tools to work together under one roof, building on one another’s strengths. A $45-million project with both federal and state funding, JIAM is scheduled to break ground in 2008 and open in 2010. Envisioned as a research and educational center for the university, it will be the latest and largest joint institute between UT and ORNL and the first new building on the Cherokee campus.
Distinguished Professor of Physics Ward Plummer is the director of JIAM. He is just back from Washington, D.C., where he was inducted into the National Academy of Sciences, and is between meetings in a very crowded week. Yet he has no trouble finding the time or enthusiasm to talk about JIAM’s interdisciplinary environment.
“When it starts to work,” he says, “I am sure all of the faculty will understand the great advantage of this mode of research.”
Putting together diverse talents is hardly new to Plummer. Since 2000 he has directed the Tennessee Advanced Materials Laboratory (TAML), the precursor to JIAM. TAML helped hire nearly two dozen new faculty members and has supported eight on-campus user facilities for materials research. That good track record bodes well for working with another new enterprise, the Sustainable Energy, Education, and Research Center, also to be located at the Cherokee site.
One of JIAM’s goals is “to integrate the sustainable energy center with the joint institute,” Plummer says. “The biggest challenges facing us are creating novel materials, and given the time scale we have, this must take a revolutionary, not an evolutionary, approach. We need interdisciplinary research.”
He quickly rattles off a list of examples: photovoltaics, hydrogen storage, catalysis, solar power, and lightweight alloys.As energy research attracts more interest, JIAM amplifies Tennessee’s role in meeting the nation’s energy challenges. In 2006 the institute named physics professor Hanno Weitering to the first JIAM Chair of Excellence. In May 2007 Weitering, who holds a joint appointment with ORNL, won a Department of Energy grant to study advanced materials for the storage and generation of hydrogen fuels.
“That’s a major coup,” Plummer says. “It gets us going and illustrates the importance of the UT–ORNL partnership.”
Cooking Up Catalysts
Weitering’s research is one of many campus initiatives that dovetail with JIAM’s mission. Another is catalysis: using catalysts to accelerate or slow down a chemical reaction. Catalysis is indispensable to manufacturing—chemical and pharmaceutical companies rely on it. And it’s an area that Craig Barnes, professor and head of the Chemistry Department, knows well.
With the easy cadence of a seasoned teacher, Barnes starts out by explaining why catalysis often involves compounds called metal oxides.
“They’re something you can heat the living daylights out of,” he says. The hitch is that conventional approaches don’t always use these oxides efficiently.
“With most traditional methods of putting these metals on a support, it’s very difficult to control how they come down and what they form,” Barnes says. He explains that you might get isolated atoms but you might also get crystals, which represent thousands, if not millions, of atoms. All will have different reactivities, which presents a problem.
“You’re not getting just one catalyst,” he says. “You’re getting many.”
A solution to this problem came to Barnes during a sabbatical in Germany. “I stumbled on this building-block idea,” he says.
Barnes developed a general synthetic method in which well-defined catalysts are incorporated into the surface structures of support materials. In this nanoscale system, all the catalyst sites are identical. They are also located far apart so they don’t interfere with one another. This approach fits well with JIAM’s mission to synthesize new materials because it allows a catalyst to help shape its immediate environment and also reveals clues about how nanostructuring can influence such properties as activity, selectivity, and longevity.
Understanding these properties plays an integral role in energy usage. The more selective a catalyst, Barnes explains, the less energy is needed for industrial processes like purification, separation, or disposal of byproducts. DOE is now emphasizing the need for ultraselective catalysts—those that result in a highly specific set of products. In this vein, the Barnes group is looking at developing catalysts that could work with methane, for example.
Fighting Fatigue
While catalysis is all about causing a reaction, Peter Liaw’s research is more focused on preventing one. Liaw holds the Ivan Racheff Chair of Excellence in Materials Science in the College of Engineering. He is a gracious host in his Dougherty Hall office, a room stacked high with scientific papers. Many of them address bulk metallic glasses, or BMGs.
Conventional metals or alloys have a crystal lattice structure, meaning that all of their atoms line up in a particular geometric order with boundaries between them. These boundaries make them susceptible to fracture and corrosion. Bulk metallic glasses, however, have an amorphous structure—their atoms have a random arrangement with no long-range order. Consequently they have much greater strength than conventional metals.
“We know the material is very good in some aspects, such as very high strengths. [It] can easily go from 1.5 to 5 GPa (gigapascals, a measure of pressure equal to 1?billion kilograms per square meter), just like that,” Liaw says, snapping his fingers.
“However, it has not much ductility, especially under tension. So our goal is to improve the ductility of this material.”
A material’s strength is defined by its ability to carry a load. Stress or force, however, can permanently change its shape. Ductility refers to how much change a material can withstand until it fractures. (In lay terms, think of flexibility.)
Liaw’s research group studies bulk metallic glasses to determine their dynamic behavior and fatigue performance. They can then change the materials’ composition to prevent failures caused by low ductility.
“We fabricate our own material here, at ORNL, in China, in Japan, or in Taiwan. We cooperate with our colleagues at UT, in the United States, and throughout the world,” he says. Compared with such conventional materials as steels, titanium alloys, and magnesium alloys, Liaw says, “as a whole, we found that the fatigue-endurance limits in bulk metallic glasses are at least as good as conventional materials.
“The beauty of BMGs is that you can fabricate all kinds of systems,” Liaw says, smiling. Making lighter materials, for example, “could increase the possibility of BMGs applied for energy or transportation applications. You use a smaller amount of energy to carry lighter weight.”
Generation, Conservation
The Joint Institute for Advanced Materials will give researchers like Liaw and Barnes the chance to work elbow to elbow creating the new materials required for advances in energy, transportation, and nanotechnology, among other fields. Gathering scientific expertise from biology, chemistry, engineering, materials science, and physics will give JIAM a formidable presence on the world stage and concentrate an impressive amount of talent on solving problems, be they finding alternative fuels or conserving natural resources.
As Plummer says, “Not only do you have to produce more energy, you’ve got to figure out how to save what we have.”
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For more information, contact Ward Plummer at 865-974-3342 or eplummer@utk.edu, Craig Barnes at 865-974-3141 or cebarnes@utk.edu, or Peter Liaw at 865-974-6356 or pliaw@utk.edu.
Ensuring the Future
When the Tennessee Advanced Materials Laboratory became a research center of excellence in 2000, a key component of the program involved attracting top students to Tennessee to study materials. Now as TAML evolves into the Joint Institute for Advanced Materials, that idea will carry over in the form of JIAM fellowships. Will they make a difference? If you ask Geoff Eldridge and Brandice Green, both TAML fellows, the answer is yes.
Geoff Eldridge says he’s happy to step out of a messy, noisy lab for a few minutes to talk about how he ended up in Tennessee. After an American Chemical Society section meeting, the Texas Lutheran alumnus received a surprise message from Mark Dadmun of the UT Knoxville Chemistry Department.
“He kind of e-mailed me out of the blue,” Eldridge says. The subject? A fellowship to study materials at UT.
“The fellowship was a big factor” in luring him to Knoxville, Eldridge says. He now works in catalysis research with Craig Barnes in the Chemistry Department.
“Catalysts,” he says, “are all about energy and saving it.” Titanium, for example, can be used in the synthesis of biodiesel. “It’s the metal for the job.”
Although he enjoys research, ultimately, Eldridge says, he would like to teach, as a way “to turn that light on for students.” As an added bonus for East Tennessee, “I’d like to stay in the area,” he says. “I really like Knoxville.”
Although a TAML fellowship drew Eldridge to the university, it’s what kept Brandice Green here. Friendly and outgoing with a bright smile, she is quick to tell you that she is interested in more than just corrosion. Green earned bachelor’s and master’s degrees in materials science and engineering at UT, but it was the TAML fellowship and the proximity of Oak Ridge National Laboratory that kept her in Tennessee for doctoral work.
“You get a chance to work with so many prominent scientists here,” she says.
Green studies the properties of bulk metallic glasses with Peter Liaw in the Materials Science and Engineering Department to figure out why these amorphous materials undergo localized corrosion. But for her, materials science is about an even wider range of research possibilities.
“I really like the idea of fuel cells,” she says, emphasizing that her education has prepared her to take on challenges in all kinds of materials-related research. “It’s completely changed the way I think about a lot of things,” she says of her graduate work. “Even if I don’t know the answer, I know what sort of questions to ask. In the long term, I’d really like to do something that makes an impact.”
For more information, contact Geoff Eldridge at eldridge@ ion.chem.utk.edu or Brandice Green at bgreen5@utk.edu.
— C. L.