By influencing how phonons travel through a crystal lattice, an electric field can begin shaping both the speed and direction of heat transport.
Researchers at Oak Ridge National Laboratory, working with scientists from The Ohio State University and Amphenol Corporation, have demonstrated a method to control heat flow in solid materials using an electric field. The findings show that certain smart ceramics can alter how heat carrying vibrations move through a crystal, enabling electrically tunable thermal transport.
The ability to regulate heat flow inside a material could have practical implications for technologies where thermal management is critical. Electrically controlled heat conduction may support improved cooling in electronic systems, more efficient solid state energy conversion and better thermal regulation in chip scale devices. Directional control of heat transport could also benefit applications where excess heat limits system performance.
The approach works by modifying how atomic vibrations move through the crystal lattice. When an electric field is applied, internal charges within the ceramic align along the field direction. This alignment reduces the scattering of phonons, the microscopic vibrations responsible for carrying heat through solids. With fewer disruptions in their path, the vibrations can travel farther before dissipating energy, resulting in longer phonon lifetimes and faster heat transport.
The effect is observed in a class of materials known as relaxor based ferroelectric ceramics. When subjected to an electric field, their internal dipoles align in a process known as poling. Measurements show that phonons moving along the field direction persist longer than those traveling perpendicular to it, increasing thermal conductivity along the field direction to nearly three times that observed across the crystal. The behavior was examined through experiments conducted at the Spallation Neutron Source using inelastic neutron scattering to observe both atomic structure and dynamic motion within the material.
Puspa Upreti, a postdoctoral research associate at Oak Ridge National Laboratory, says that the work points toward new possibilities for managing thermal energy in advanced materials. “Being able to control both how fast and in what manner heat flows could lead to devices that manage thermal energy far more efficiently.”
