Carnegie Mellon University
May 13, 2013

Press Release: Carnegie Mellon Researchers Develop New Tool For Measuring How Materials Transfer Heat

Contact: Chriss Swaney / 412-268-5776 /

PITTSBURGH—Making bits and bytes smaller creates more heat. So, manufacturers continue to seek ways of tracking heat transfer in products as diverse as a computer's silicon chips to light-emitting diodes or solar cells.

Carnegie Mellon University researchers Jonathan A. Malen, Alan J.H. McGaughey, Keith Regner and Zonghui Su have developed a new tool called broadband frequency domain thermal reflectance to measure the thermal and vibrational properties of solids. In a recent paper published in Nature Communications, the CMU team collaborated with Christina Amon and Daniel Sellan from the University of Toronto to study materials in which heat is transferred by atomic vibrations in packets called phonons.

"In an analogy to light, phonons come in a spectrum of colors, and we have developed a new tool to measure how different color phonons contribute to the thermal conductivity of solids," said Malen, an assistant professor of mechanical engineering. "Our study provides the first experimental resolution to how individual phonons impact thermal conductivity."

According to the CMU researchers, the new tool will give both industry and academia a clearer picture of how an electronic device's dissipative ability shrinks with its size, and how materials can be structured at the nanoscale to change their thermal conductivity.

For example, in the initial demonstration, the CMU team showed that as silicon microprocessors continue to shrink according to Moore's Law, their operating temperatures will be further challenged by reduced thermal conductivity. But knowledge of the individual phonon contributions also will allow researchers to better design nanostructured thermoelectric materials with an increased efficiency of converting waste heat to electrical energy.

Earlier this year, Malen and McGaughey used nanocrystal arrays to explore heat flow in hybrid organic-inorganic materials. Such materials are touted as a cost-and-resource-effective alternative to conventional semiconductors in energy production.

Funding for this research was provided by the National Science Foundation and the Air Force Office of Scientific Research.