By Emily Hubbell

Imagine a cell phone that runs on its user’s body heat or a car powered by the thermal energy emitted from its engine. Both of these rely on materials that convert waste heat directly into electricity.

These implications of energy conservation aren’t lost on Dr. Gang Chen, the newest member of NQPI. Chen is currently conducting research that analyzes the thermal, electrical and phase transition characteristics of confined nanoscale materials, in hopes of discovering new ways to conserve energy.

“Enhanced thermo-electric properties —that’s why we want to study confinement,” said Chen, assistant professor of physics and astronomy. “An ideal thermo-electric material has excellent electric conductivity but poor thermal conductivity – exactly the opposite of diamond.” He added that by confining traditional thermo-electric materials in nanosized pores, it is possible to enhance the performance of those materials.

In the lab at OU, Chen’s research group x-rays confined nanoparticles to analyze their structure, morphology and properties. He conducts additional research in the synchrotron facility at Argonne National Laboratory, a U.S. Department of Energy research center, located just outside of Chicago, according to the ANL Web site.

Confined substances can exhibit properties significantly different from their non-confined counterparts. For example, water—which usually becomes ice at 32 degrees F— does not fully freeze until -40 degrees F when confined in nanosized pores, Chen said.

Chen is currently focusing on two classes of materials: thermoelectric materials and phase-change memory materials.

These phase-change memory materials include chalcogenides, which contain chalcogen atoms such as S, Se and Te. Chalcogenides help with information storage in many devices, including Blu-Ray disks.

 
In a Blu-Ray disk, a laser beam carries enough energy to melt the chalcogenide inside the disk. During its transition from the liquid to solid phase, the chalcogenide has distinct electric and optical properties, which are used for data storage, Chen said.

“By confining the chalcogenide inside nanosized pores, we hope the phase transition temperature can be lowered so that it consumes less power,” Chen said, adding that there is likewise the possibility that the duration of the material’s phase transition could be shortened.

 
Chen’s research group is also interested in using phase-change materials for non-volatile memory—next-generation memory in computers and other electronic devices. Nanoscale confinement provides a new opportunity to modify the materials properties.

“The challenge is that we want to understand at a fundamental level how nanoscale confinement affects the properties of these materials,” he said.