Work on Electrical Output of Thermoelectric Materials Results in Award

Jeremiah T. Abiade, assistant professor in materials science and engineering and in mechanical engineering at Virginia Tech, has received a Ralph E. Powe Junior Faculty Enhancement Award for his research to increase the electrical output of thermoelectric (TE) materials and devices.

Oak Ridge Associated Universities (ORAU) presents the Powe award to faculty members who are in the first two years of their tenure track as an investment in promising achievements in an important area. The award to Abiade will support his research to fabricate thick and thin film oxide thermoelectrics.

Thermoelectric devices are capable of converting temperature differences at the junctions of dissimilar materials into electric voltages. "We are interested in thermoelectrics for energy harvesting because of the potential to create nonpolluting power from waste heat," said Abiade.

For example thermoelectric generators are being used to provide power in automobiles by harvesting heat from the vehicles exhaust system. Thermoelectric generators are prime candidates for future vehicles that will be lightweight with higher fuel economy and increased electrical power requirements, Abiade suggested.

"However, thermoelectric properties, commonly described by the thermoelectric figure of merit (ZT), are too low, limiting the use of thermoelectric devices to niche applications. In order to make them more widespread, we have to enhance ZT for useful power output."

Major improvements in thermoelectric devices have been obtained using nanocomposite and nanoscale thermoelectrics. In the nanocomposite approach, which Abiade's group is using, the objective is to minimize thermal conductivity of the materials using nanoparticles to scatter phonons (atomic vibrations) primarily responsible for heat conduction in nonmetals. The value of ZT increases if the thermal conductivity is decreased.

"Since the change in temperature and heat flow through the material is critical for power generation, the challenge is to decrease thermal conductivity while not negatively impacting the electrical conductivity," he said.

Abiade's group is interested in improving the thermoelectric properties of doped strontium titanates, a type of oxide material. "We are interested in oxides in general because they have very interesting properties, such as the ability to be either insulating or superconducting, and they are generally very stable at high temperatures," he said. His group conducts their research in the Laboratory for Oxide Research and Education (http://lore.mse.vt.edu/research/index.html).

The group has synthesized several samples with inert, metallic nanoparticles embedded in the bulk strontium titanate material, and is measuring the thermal transport properties in collaboration with mechanical engineering Assistant Professor Scott Huxtable and the Virginia Tech Nanoscale Energy Transport Lab. Abiade, Huxtable, and their colleagues recently published related research in the April, 17, 2009, issue of Applied Physics Letters ("Thermal transport in composites of self-assembled nickel nanoparticles embedded in yttria stabilized zirconia," by mechanical engineering graduate students Nitin C. Shukla and Hao-Hsiang Liao; Abiade; Mitsuhiro Murayama, research assistant professor with Virginia Tech's Institute for Critical Technology and Applied Science; Professor Dhananjay Kumar from North Carolina A&T State University; and Huxtable).

Similar work by Abiade is also being supported by a National Science Foundation Broadening Participation Research Initiation Grants in Engineering (BRIGE) program, "An Integrated Research and Educational Approach to High Efficiency Nanocomposite Thermoelectric Materials & Devices," which supports Abiade's mechanical engineering master's student, Daniel Osborne of Wilmington, Del.

Abiade received his bachelor's degree in physics from Southern University and A&M College in 1999 where he was a member of the Timbuktu Academy and his Ph.D. in materials science and engineering from the University of Florida in 2004. He was a postdoctoral associate in the North Carolina A&T State University Department of Mechanical and Chemical Engineering before joining the faculty at Virginia Tech.

The Powe award competition permits only two applications from each of ORAU's 115 university members. Both Virginia Tech applicants were selected. The second winner is Pablo Sobrado, assistant professor of biochemistry with the infectious disease research group.