Scientists in the United States have discovered an electric field method to improve heat flow in materials.
The team from the Oak Ridge National Laboratory (ORNL), working with scientists from The Ohio State University and Amphenol Corporation found that the new method controls heat flow in solid materials by using an electric field.
They revealed that applying an electric field to a special ceramic material can change the behavior of phonons—tiny vibrations of atoms that carry heat through a material.
Heat can move through material almost three times more efficiently
When the electric field is applied, phonons moving in the direction of the field last longer and travel farther than those moving in other directions. As a result, heat can move through the material almost three times more efficiently along the direction of the electric field, offering a powerful way to manage thermal energy in advanced technologies.
“Being able to control both how fast and in what manner heat flows could lead to devices that manage thermal energy far more efficiently,” said Puspa Upreti, an ORNL postdoctoral research associate.
Controlling heat flow is important for high-performance systems such as modern electronic coolers with no moving parts, energy converters that change heat into power, chip-based circuits used in everyday technology, and cogeneration systems, which capture and repurpose industrial heat. Regulating heat in these systems creates the right conditions for peak efficiency and performance, according to a press release.
New approach achieved an enhancement
Scientists reported that earlier research on similar materials typically increased heat conductivity by only about 5–10 percent, but this new approach achieved an enhancement close to 300 percent. By combining neutron-scattering data with thermal conductivity measurements, the researchers directly linked the improved heat flow to longer-lasting phonons traveling through the crystal lattice. This breakthrough could lead to new solid-state technologies that efficiently manage heat in electronics, energy-conversion devices, chip-based circuits, and industrial systems that recycle waste heat.
The experiments were conducted at ORNL’s Spallation Neutron Source, where scientists used advanced neutron-scattering techniques to observe both the atomic structure and the motion of atoms inside the material. Neutrons allowed the researchers to precisely measure how the atomic vibrations changed when the electric field was applied.
The study focused on a type of “smart” ceramic known as a relaxor-based ferroelectric. In these materials, applying an electric field aligns small electric charges within the crystal structure, reducing the scattering of heat-carrying vibrations. This alignment allows energy to flow more smoothly through the material, significantly increasing thermal conductivity.
Published in PRX Energy, the study reveals that the significant changes in phonon transport with the application of an electric field over a broad temperature range in a relaxor-based ferroelectric using neutron-scattering and -transport measurements.
“We also observe a suppression of nanoscale antiferroelectric fluctuations along the poling direction and argue that this increases the phonon lifetimes. Our results highlight a promising yet underexplored route to realistic solid-state heat switching from electric-field-modified nanostructures altering the phonon lifetimes in disordered functional materials,” said researchers in the study.