Sun, Jul 07, 2013 - Page 3 News List

NTU research team discovers new heat transfer model

By Lee I-chia  /  Staff reporter

Hsiao Tzu-kan, left, and Chang Chih-wei from National Taiwan University’s Center for Condensed Matter Sciences pose for a photograph at the school on Friday.

Photo: Fang Pin-chao, Taipei Times

A research team from National Taiwan University’s (NTU) Center for Condensed Matter Sciences has discovered a new model of heat transfer without dissipation or collision, rewriting the models of heat transfer in current textbooks.

The team led by the center’s assistant researcher Chang Chih-wei (張之威) said scientists have known that the wave nature of heat transport is more pronounced in low- temperature conditions.

He said his team had discovered that by using silicon-germanium nanowires at room temperature, the wave characteristics of phonons could allow the transmission of energy without dissipation.

Chang said the traditional model of heat transfer taught in textbooks is like pouring cream into a cup of coffee: The cream substance would collide with each other and gradually disperse in the coffee, but would also damage the wave characteristics of the heat transfer itself, making it incapable of transmitting information like that through electronics or optical fiber.

“When heat transfers with wave characteristics and does not have collisions, it can carry information, kind of like that of optic communication,” he said.

“Previously, it was thought that to observe the phenomenon of wave characteristics of heat-transfer-specific materials, such as diamond or carbon nanotube, were needed, and that the temperature must drop significantly,” Chang said. “However, we also observed the phenomenon using a very common semiconductor — silicon-germanium nanowires — and at room temperature.”

The main contributor to the team’s new discovery is the center’s research assistant Hsiao Tzu-kan (蕭子綱) after spending more than a year trying out the experiment with various nanowires and testing for results.

The team said its discovery not only challenges current knowledge on the traditional heat transfer model, but may also change the design models of current electronic circuits.

Their research was published in this month’s Nature Nanotechnology journal.

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