#phasons

Cooking with Phason Gas

Heat-transport measurements and neutron-scattering spectroscopy probe a form of thermal conduction based on excitations called phasons. 

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The understanding of how substances conduct heat is of great significance in materials science. It is needed for many important technological applications—from heat management in electronics to temperature control in buildings [1]. Therefore, when an unusual form of thermal transport is identified, materials scientists take notice. Michael Manley of Oak Ridge National Laboratory, Tennessee, and his colleagues have shown that excitations called phasons can provide the main contribution to thermal transport in a material known as fresnoite [2]. Phasons are collective lattice oscillations that occur in certain crystals with an aperiodic lattice structure—fresnoite being one of the best known. The researchers’ demonstration could pave the way for new heat-management strategies.

Thermal conductivity is a measure of a material’s ability to transfer heat. It is a property that we are all abruptly reminded of when we accidentally place our hand on a hot kitchen stove. The temperature gradient between our cooler skin and the hotter surface facilitates a transfer of energy into our hand, resulting in an unpleasant sensation. The notion that different materials conduct heat at different rates is similarly experienced when we perceive the cooling sensation of holding a metal spoon relative to a wooden one.

Supersonic waves may help electronics beat the heat

Researchers at the Department of Energy's Oak Ridge National Laboratory made the first observations of waves of atomic rearrangements, known as phasons, propagating supersonically through a vibrating crystal lattice -- a discovery that may dramatically improve heat transport in insulators and enable new strategies for heat management in future electronics devices.

"The discovery gives you a different way to control the flow of heat," said lead author Michael Manley of the paper published in Nature Communications. "It provides a shortcut through the material -- a way to send the energy of pure atomic motion at a speed that's higher than you can with phonons [atomic vibrations]. This shortcut may open possibilities in heat management of nanoscale materials. Imagine the possibility of a thermal circuit breaker, for example."

The scientists used neutron scattering to measure phasons with velocities about 2.8 times and about 4.3 times faster than the natural "speed limits" of longitudinal and transverse acoustic waves, respectively. "We didn't expect them to be going that fast without [fading]," Manley said.

Science, Volume 389, Issue 6758, Page 423-428, July 2025. Summary Without knowing the specific content of the article "Science, Volume 389, Issue 6758, Page 423-428, July 2025," I can only provide a generalized summary based on its format. The article, published in a specific issue of the prominent science journal Science, likely presents original scientific research or a significant review on a…